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Sample records for bed combustion ash

  1. Ash and heavy metals in fluidized bed-combustion; Tuhka ja raskasmetallit puuperaeisen jaetteen kerrosleijupoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Kaessi, T.; Aittoniemi, P. [IVO International, Vantaa (Finland)

    1996-12-01

    Combustion ashes and submicron fly ash particles were characterized in two industrial boilers (bubbling vs. circulating fluidized bed) burning paper mill deinking sludge and bark or wood as support fuel. Bulk samples from fly ash, circulating ash and bottom ash were analyzed. Fine particles in fly ash were monitored and sampled for microscopic studies. The mass size distribution of fly ash was measured and the chemical composition according to particle size was analyzed. The results showed that ash consists of large and friable clusters formed by sintering of small mineral particles originating from paper fillers. Very few ash particles were fused and they were found only among the smallest particles. No agglomerates of fused particles were found. If the residence time in furnace is long enough sintering may proceed further and ash structure grows more dense. No indication of ash vaporization was detected. These results were similar for bubbling and circulating fluidized bed boilers. (author)

  2. Fluidized bed combustion bottom ash: A better and alternative geo-material resource for construction.

    Science.gov (United States)

    Mandal, A K; Paramkusam, Bala Ramudu; Sinha, O P

    2018-04-01

    Though the majority of research on fly ash has proved its worth as a construction material, the utility of bottom ash is yet questionable due to its generation during the pulverized combustion process. The bottom ash produced during the fluidized bed combustion (FBC) process is attracting more attention due to the novelty of coal combustion technology. But, to establish its suitability as construction material, it is necessary to characterize it thoroughly with respect to the geotechnical as well as mineralogical points of view. For fulfilling these objectives, the present study mainly aims at characterizing the FBC bottom ash and its comparison with pulverized coal combustion (PCC) bottom ash, collected from the same origin of coal. Suitability of FBC bottom ash as a dike filter material in contrast to PCC bottom ash in replacing traditional filter material such as sand was also studied. The suitability criteria for utilization of both bottom ash and river sand as filter material on pond ash as a base material were evaluated, and both river sand and FBC bottom ash were found to be satisfactory. The study shows that FBC bottom ash is a better geo-material than PCC bottom ash, and it could be highly recommended as an alternative suitable filter material for constructing ash dikes in place of conventional sand.

  3. Electron microscopy and phase analysis of fly ash from pressurized fluidized bed combustion

    International Nuclear Information System (INIS)

    Maenami, Hiroki; Isu, Norifumi; Ishida, Emile H.; Mitsuda, Takeshi

    2004-01-01

    The characterization of the typical fly ashes from pressurized fluidized bed combustion system (PFBC) in Japan and Europe was carried out by electron microscopy and phase analysis using energy-dispersive X-ray spectroscopy (EDX). The purity of limestone as in-bed sulfur removal sorbent influences the desulfurization reaction. The high-purity limestone yielded both hydroxyl ellestadite and anhydrite in Japanese PFBC ashes, while dolomite-rich limestone yielded anhydrite in European PFBC ashes. When the high-purity limestone was used, hydroxyl ellestadite particles were observed as the independent particles or the rim around limestone particles. The Al 2 O 3 content in the glassy phase was inversely proportional to the CaO content in the glassy phase, suggesting that the glassy phases were formed from metakaoline and calcite as end members. Since hydroxyl ellestadite, glassy phase and metakaoline are reactive under hydrothermal conditions, PFBC ashes are expected to be used as raw materials for autoclaved products

  4. Ash and heavy metals in fluidized-bed combustion of wood wastes; Tuhka ja raskasmetallit puuperaeisen jaetteen kerrosleijupoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Kaessi, T; Aittoniemi, P [IVO Power Engineering, Vantaa (Finland); Kauppinen, E; Latva-Somppi, J; Kurkela, J [VTT Chemical Technology, Espoo (Finland); Partanen, J [IVO Technology Centre, Vantaa (Finland)

    1997-10-01

    Ash formation and deposition mechanisms during co-combustion of pulp mill sludge and bark in industrial bubbling fluidized bed (BFB) combustor have been studied. Similar fuels were used in a bench-scale BFB for co-combustion of sludge and bark pellets and comparative studies with separate combustion of these fuels. Results indicated that in industrial scale unit significant fraction of ash had vaporization. About 14 mass-% of the total fly ash was found in the particle size below 0.2 {mu}m. The vaporized species consisted of potassium (K), sulfur (S), chlorine (Cl) and also of minor quantities of sodium (Na). In the benchscale similar vaporization fractions during co-combustion were measured, about 11 mass-%. During the combustion of bark this ratio, about 20 mass-%, was higher than during sludge combustion. The vaporized ash fraction was in the case of dried sludge combustion about 7 mass-%, but with wet sludge the vaporization rate was remarkably lower, about 1-2 mass-%. An increase in the bed temperature increased also ash vaporization. Test run period without combustion at elevated temperatures produced very low quantities of vaporized ash. The vaporized species in bench-scale test during bark pellet combustion were K, S and Cl, for sludge combustion also Na was clearly detected. No condensation of the vaporized species in bed area or furnace walls was observed. Bed defluidization was studied in the bench-scale unit. During bark pellet combustion the bed-agglomeration proceeded via small ash particle, below 2 {mu}m, coating on sand particle surface and consequent bonding between the ash layers. In the case of sludge combustion the accumulation of large ash particles and sintering of these porous agglomerates was observed to cause bed coarsening and defluidization. (orig.)

  5. Properties of Controlled Low Strength Material with Circulating Fluidized Bed Combustion Ash and Recycled Aggregates

    Science.gov (United States)

    Weng, Tsai-Lung; Cheng, An; Chao, Sao-Jeng; Hsu, Hui-Mi

    2018-01-01

    This study aims to investigate the effect of adding circulating fluidized bed combustion (CFBC) ash, desulfurization slag, air-cooled blast-furnace slag and coal bottom ash to the controlled low-strength material (CLSM). Test methods include slump flow test, ball drop test, water soluble chloride ion content measurement, compressive strength and length change measurement. The results show that (1) the use of CFBC hydration ash with desulfurization slag of slump flow is the best, and the use of CFBC hydration ash with coal bottom ash and slump flow is the worst; (2) CFBC hydration ash with desulfurization slag and chloride ion content is the highest; (3) 24 h ball drop test (diameter ≤ 76 mm), and test results are 70 mm to 76 mm; (4) CFBC hydration ash with desulfurization slag and compression strength is the highest, with the coal bottom ash being the lowest; increase of CFBC hydration ash can reduce compressive strength; and (5) the water-quenched blast furnace slag and CFBC hydration ash would expand, which results in length changes of CLSM specimens. PMID:29724055

  6. Enrichment of thallium in fly ashes in a Spanish circulating fluidized-bed combustion plant

    OpenAIRE

    López Antón, María Antonia; Spears, D. Alan; Díaz Somoano, Mercedes; Díaz, Luis; Martínez Tarazona, María Rosa

    2015-01-01

    This work evaluates the behavior of thallium in a 50 MW industrial circulating fluidized-bed combustion plant (CFBC), focusing on the distribution of this element among the bottom and fly ashes separated by the solid retention devices in the plant. The results show that thallium species are mainly retained in the solid by-products and are not emitted to air with flue gases in significant amounts, proving that this technology is a more effective means of preventing thallium emissions than pulv...

  7. Combustion of Biosolids in a Bubbling Fluidized Bed, Part 1: Main Ash-Forming Elements and Ash Distribution with a Focus on Phosphorus.

    Science.gov (United States)

    Skoglund, Nils; Grimm, Alejandro; Ohman, Marcus; Boström, Dan

    2014-02-20

    This is the first in a series of three papers describing combustion of biosolids in a 5-kW bubbling fluidized bed, the ash chemistry, and possible application of the ash produced as a fertilizing agent. This part of the study aims to clarify whether the distribution of main ash forming elements from biosolids can be changed by modifying the fuel matrix, the crystalline compounds of which can be identified in the raw materials and what role the total composition may play for which compounds are formed during combustion. The biosolids were subjected to low-temperature ashing to investigate which crystalline compounds that were present in the raw materials. Combustion experiments of two different types of biosolids were conducted in a 5-kW benchscale bubbling fluidized bed at two different bed temperatures and with two different additives. The additives were chosen to investigate whether the addition of alkali (K 2 CO 3 ) and alkaline-earth metal (CaCO 3 ) would affect the speciation of phosphorus, so the molar ratios targeted in modified fuels were P:K = 1:1 and P:K:Ca = 1:1:1, respectively. After combustion the ash fractions were collected, the ash distribution was determined and the ash fractions were analyzed with regards to elemental composition (ICP-AES and SEM-EDS) and part of the bed ash was also analyzed qualitatively using XRD. There was no evidence of zeolites in the unmodified fuels, based on low-temperature ashing. During combustion, the biosolid pellets formed large bed ash particles, ash pellets, which contained most of the total ash content (54%-95% (w/w)). This ash fraction contained most of the phosphorus found in the ash and the only phosphate that was identified was a whitlockite, Ca 9 (K,Mg,Fe)(PO 4 ) 7 , for all fuels and fuel mixtures. With the addition of potassium, cristobalite (SiO 2 ) could no longer be identified via X-ray diffraction (XRD) in the bed ash particles and leucite (KAlSi 2 O 6 ) was formed. Most of the alkaline-earth metals

  8. Fluidized-bed-combustion ash for the solidification and stabilization of a metal-hydroxide sludge.

    Science.gov (United States)

    Knoll, K L; Behr-Andres, C

    1998-01-01

    Fluidized-bed-combustion (FBC) ash is a by-product from a developing technology for coal-fired power plants that will economically reduce air emissions to meet requirements of the Clean Air Act. FBC ash has physical and chemical properties similar to Portland cement, but only has moderate success as a pozzolan in concrete applications due to low compressive strengths. However, FBC ash has proven effective for use as a binder for the solidification and stabilization (S/S) of metal-bearing sludges. Physical and chemical characterization procedures were used to analyze FBC ash and a metal-bearing sludge obtained from a hazardous waste treatment facility to develop 12 different S/S mix designs. The mix designs consist of four binder designs to evaluate sludge-to-binder ratios of approximately 0, 0.5, and 1. Portland cement is used as a control binder to compare unconfined compressive strengths and Toxicity Characteristic Leaching Procedure (TCLP) analyses from different ratios of the FBC ash streams: fly ash, char, and spent bed material (SBM). Compressive strengths ranging from 84 lbs per square inch (psi) to 298 psi were obtained from various mix designs containing different sludge-to-ash ratios cured for 28 days. All the mix designs passed the TCLP. Recoveries from leaching for each metal were less than 5% for most mix designs. Results of unconfined compressive strengths, TCLP, and percent recovery calculations indicate that the mix design containing approximately a 1:1 ratio of fly ash to char-and-sludge is the best mix design for the S/S of the metal-bearing sludge.

  9. Stabilization of ash from combustion of MSW in a fluidised bed boiler

    Energy Technology Data Exchange (ETDEWEB)

    Steenari, Britt-Marie; Wilewska, Magda [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Environmental Inorganic Chemistry

    2004-06-01

    Due to restrictions against the land filling of combustible waste and directives from authorities that favour energy recovery from the waste, combustion of household waste is becoming more common. Even though combustion of MSW reduces the volume of waste to be handled by approximately 90%, it produces ash residues containing most of the metals present in the original fuel and a number of other species carried through the boiler or formed during combustion. The residues can be divided into three categories: 1. Stable, inert ash that can be utilised in, for example, construction applications 2. Ash that is stable enough to be land filled as nonhazardous waste 3. Ash that contains large amounts of soluble components and potentially toxic metal species. The regulations considering leaching of ash components set limits for the release of soluble salts and toxic metals. Some fly ashes show low leachability for metals but gives a salt release that is too close to the limit for total dissolved solids. Since fly ash from FBC boilers represent the largest volume of ash from these boilers there is a need for a simple and cheap treatment method that reduces the amount of soluble salts, i.e. NaCl, KCl etc, in the ash. After stabilisation, the ash is supposed to go into a more stable category. The aim of this project has been to investigate the applicability of a method to wash such an ash with water. The work included laboratory studies of the ash properties, the water washing process, filtration properties of the ash slurry and also tests of the method in pilot scale at a full scale boiler. This work has been concentrated towards the investigation of cyclone ash from a bubbling fluidised bed boiler in Lidkoeping fired with 100% household waste. Elemental composition of ash samples before and after washing/filtration was determined by AAS or ICP after a suitable dissolution of the sample. The mineralogy of ash samples was analysed using X-ray powder diffractometry. This method

  10. Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor.

    Science.gov (United States)

    Lapa, N; Barbosa, R; Lopes, M H; Mendes, B; Abelha, P; Boavida, D; Gulyurtlu, I; Oliveira, J Santos

    2007-08-17

    In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub-products of such type

  11. Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lapa, N. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)]. E-mail: ncsn@fct.unl.pt; Barbosa, R. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Lopes, M.H. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Mendes, B. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Abelha, P. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Gulyurtlu, I. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Santos Oliveira, J. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)

    2007-08-17

    In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

  12. Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

    International Nuclear Information System (INIS)

    Lapa, N.; Barbosa, R.; Lopes, M.H.; Mendes, B.; Abelha, P.; Gulyurtlu, I.; Santos Oliveira, J.

    2007-01-01

    In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

  13. Effect of coal blending on the leaching characteristics of arsenic and selenium in fly ash from fluidized bed coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, F.; Yamada, N.; Sato, A.; Ninomiya, Yoshihiko [Chubu Univ., Aichi (Japan). Dept. of Applied Chemistry; Zhang, L. [Monash Univ., Clayton, VIC (Australia). Dept. of Chemical Engineering

    2013-07-01

    The capture ability of fly ash to arsenic (As) and selenium (Se) was investigated through the combustion of two single bituminous coals A and B and their mixture (blending ratio of 1:1, wt/wt) in a lab-scale fluidized bed reactor. The leaching characteristics of As and Se in corresponding fly ash were also conducted according to Japanese Industrial Standard (JIS). Speciation of As and Se during fly ash leaching test were predicted from the perspective of thermodynamic equilibrium. The results indicate that, combustion of coal B, containing abundant calcium, possesses a higher capture ability of As and Se than that of coal A through possible chemical reaction between As/Se with CaO. Leaching behavior of As and Se from fly ash is strongly dependent on the pH of the leachate. Free calcium in fly ash generates an alkaline leachate during leaching test and subsequently reduces As and Se leaching, which cause the leaching ratio of As and Se in fly ash derived from the combustion of coal B was much lower, relative to that in coal A. Combustion of blending coal promotes the overall capture ability of the fly ash to As/Se and reduces their leaching from fly ash through the synergy of free CaO between this two kind of fly ash.

  14. Characterization of ashes from a 100 kWth pilot-scale circulating fluidized bed with oxy-fuel combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.H.; Wang, C.B.; Tan, Y.W.; Jia, L.F.; Anthony, E.J. [Natural Resources Canada, Ottawa, ON (Canada)

    2011-09-15

    Oxy-fuel combustion experiments have been carried out on an oxygen-fired 100 kW(th) mini-circulating fluidized bed combustion (CFBC) facility. Coal and petroleum coke were used as fuel together with different limestones (and fixed Ca:S molar ratios) premixed with the fuel, for in situ SO{sub 2} capture. The bed ash (BA) and fly ash (FA) samples produced from this unit were collected and characterized to obtain physical and chemical properties of the ash samples. The characterization methods used included X-ray fluorescence (XRF), X-ray diffraction (XRD), char carbon and free lime analysis, thermogravimetric analysis (TGA), and surface analysis. The main purpose of this work is to characterize the CFBC ashes from oxy-fuel firing to obtain a better understanding of the combustion process, and to identify any significant differences from the ash generated by a conventional air-fired CFBC. The primary difference in the sulfur capture mechanism between atmospheric air-fired and oxy-fuel FBC, at typical FBC temperatures (similar to 850{sup o}C), is that, in the air-fired case the limestone sorbents calcine, whereas the partial pressure of CO{sub 2} in oxy-fuel FBC is high enough to prevent calcination, and hence the sulfation process should mimic that seen in pressurized FBC (PFBC). Here, the char carbon content in the fly ash was much higher than that in the bed ash, and was also high by comparison with ash obtained from conventional commercial air-firing CFBC units. In addition, measurements of the free lime content in the bed and fly ash showed that the unreacted Ca sorbent was present primarily as CaCO{sub 3}, indicating that sulfur capture in the oxy-fuel combustor occurred via direct sulfation.

  15. Fluid-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, G.; Schoebotham, N.

    1981-02-01

    In Energy Equipment Company's two-stage fluidized bed system, partial combustion in a fluidized bed is followed by burn-off of the generated gases above the bed. The system can be retrofitted to existing boilers, and can burn small, high ash coal efficiently. It has advantages when used as a hot gas generator for process drying. Tests on a boiler at a Cadbury Schweppes plant are reported.

  16. Characteristics of ash and particle emissions during bubbling fluidised bed combustion of three types of residual forest biomass.

    Science.gov (United States)

    Ribeiro, João Peres; Vicente, Estela Domingos; Alves, Célia; Querol, Xavier; Amato, Fulvio; Tarelho, Luís A C

    2017-04-01

    Combustion of residual forest biomass (RFB) derived from eucalypt (Eucalyptus globulus), pine (Pinus pinaster) and golden wattle (Acacia longifolia) was evaluated in a pilot-scale bubbling fluidised bed reactor (BFBR). During the combustion experiments, monitoring of temperature, pressure and exhaust gas composition has been made. Ash samples were collected at several locations along the furnace and flue gas treatment devices (cyclone and bag filter) after each combustion experiment and were analysed for their unburnt carbon content and chemical composition. Total suspended particles (TSP) in the combustion flue gas were evaluated at the inlet and outlet of cyclone and baghouse filter and further analysed for organic and elemental carbon, carbonates and 57 chemical elements. High particulate matter collection efficiencies in the range of 94-99% were observed for the baghouse, while removal rates of only 1.4-17% were registered for the cyclone. Due to the sand bed, Si was the major element in bottom ashes. Fly ashes, in particular those from eucalypt combustion, were especially rich in CaO, followed by relevant amounts of SiO 2 , MgO and K 2 O. Ash characteristics varied among experiments, showing that their inorganic composition strongly depends on both the biomass composition and combustion conditions. Inorganic constituents accounted for TSP mass fractions up to 40 wt%. Elemental carbon, organic matter and carbonates contributed to TSP mass fractions in the ranges 0.58-44%, 0.79-78% and 0.01-1.7%, respectively.

  17. Fly ash classification efficiency of electrostatic precipitators in fluidized bed combustion of peat, wood, and forest residues.

    Science.gov (United States)

    Ohenoja, Katja; Körkkö, Mika; Wigren, Valter; Österbacka, Jan; Illikainen, Mirja

    2018-01-15

    The increasing use of biomasses in the production of electricity and heat results in an increased amount of burning residue, fly ash which disposal is becoming more and more restricted and expensive. Therefore, there is a great interest in utilizing fly ashes instead of just disposing of it. This study aimed to establish whether the utilization of fly ash from the fluidized bed combustion of peat, wood, and forest residues can be improved by electrostatic precipitator separation of sulfate, chloride, and some detrimental metals. Classification selectivity calculations of electrostatic precipitators for three different fuel mixtures from two different power plants were performed by using Nelson's and Karnis's selectivity indices. Results showed that all fly ashes behaved similarly in the electrostatic separation process SiO 2 resulted in coarse fractions with Nelson's selectivity of 0.2 or more, while sulfate, chloride, and the studied detrimental metals (arsenic, cadmium, and lead) enriched into fine fractions with varying selectivity from 0.2 to 0.65. Overall, the results of this study suggest that it is possible to improve the utilization potential of fly ashes from fluidized bed combustion in concrete, fertilizer, and earth construction applications by using electrostatic precipitators for the fractionating of fly ashes in addition to their initial function of collecting fly ash particles from flue gases. The separation of the finer fractions (ESP 2 and 3) from ESP 1 field fly ash is recommended. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Low-reactive circulating fluidized bed combustion (CFBC) fly ashes as source material for geopolymer synthesis

    International Nuclear Information System (INIS)

    Xu Hui; Li Qin; Shen Lifeng; Zhang Mengqun; Zhai Jianping

    2010-01-01

    In this contribution, low-reactive circulating fluidized bed combustion (CFBC) fly ashes (CFAs) have firstly been utilized as a source material for geopolymer synthesis. An alkali fusion process was employed to promote the dissolution of Si and Al species from the CFAs, and thus to enhance the reactivity of the ashes. A high-reactive metakaolin (MK) was also used to consume the excess alkali needed for the fusion. Reactivities of the CFAs and MK were examined by a series of dissolution tests in sodium hydroxide solutions. Geopolymer samples were prepared by alkali activation of the source materials using a sodium silicate solution as the activator. The synthesized products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffractography (XRD), as well as Fourier transform infrared spectroscopy (FTIR). The results of this study indicate that, via enhancing the reactivity by alkali fusion and balancing the Na/Al ratio by additional aluminosilicate source, low-reactive CFAs could also be recycled as an alternative source material for geopolymer production.

  19. Ash related bed agglomeration during fluidized bed combustion, further development of the classification method based on CCSEM; CCSEM-luokitusmenetelmaen jatkokehittaeminen tuhkan aiheuttaman agglomeroitumisen tutkimisessa leiju- ja kiertopetipoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, R; Patrikainen, T; Heikkinen, R; Tiainen, M; Virtanen, M [Oulu Univ. (Finland). Inst. of Chemistry

    1997-10-01

    The scope of this project is to use the information and experience gained from the development of classification method to predict ash related problems like bed agglomeration during fluidised combustion. If boilers have to be shut down due to slagging or agglomeration of the bed material may cause significant economic losses for the entire energy production chain. Mineral classification methods based on the scanning electron microscopy are commonly used for coal ash investigation. In this work different biomass, peat, and peat-wood ash, fluidised-bed materials, and bed agglomerates were analysed with SEM-EDS combined with automatic image analysis software. The properties of ash particles are different depending on the fuel type. If biomass like wood or bark are added to peat the resulting ash has different properties. Due to the low mineral content in the original peat and to the fact that the majority of inorganic material is bound to the organic matrix, the classification has turned out to be less informative than was hoped. However, good results are obtained the by use of quasiternary diagrams. With these diagrams the distribution of particle composition is easily illustrated and thus meaningful prediction can be made of the slagging and agglomerating properties of ash. The content of ten different elements are determined for each particle by SEM-EDS combined with Link AIA software. The composition of the diagram corners can be varied Freely within these ten elements. (orig.)

  20. Fixed-bed studies of the interactions between mercury and coal combustion fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, Grant E.; DeWall, Raymond A. [Energy and Environmental Research Center, 15 North 23rd Street, Grand Forks, ND 58203 (United States); Senior, Constance L. [Reaction Engineering International, 77 West 200 South, Suite 210, Salt Lake City, UT 84101 (United States)

    2003-08-15

    Sixteen different fly ash samples, generated from both pilot-scale and full-scale combustion systems, were exposed to a simulated flue gas containing either elemental mercury or HgCl{sub 2} in a bench-scale reactor system at the Energy and Environmental Research Center to evaluate the interactions and determine the effects of temperature, mercury species, and ash type on adsorption of mercury and oxidation of elemental mercury. The fly ash samples were characterized for surface area, loss on ignition, and forms of iron in the ash. While many of the ash samples oxidized elemental mercury, not all of the samples that oxidized mercury also captured elemental mercury. However, no capture of elemental mercury was observed without accompanying oxidation. Generally, oxidation of elemental mercury increased with increasing amount of magnetite in the ash. However, one high-carbon subbituminous ash with no magnetite showed considerable mercury oxidation that may have been due to unburned carbon. Surface area as well as the nature of the surface appeared to be important for oxidation and adsorption of elemental mercury. The capacity of the ash samples for HgCl{sub 2} was similar to that for elemental mercury. There was a good correlation between the capacity for HgCl{sub 2} and the surface area; capacity decreased with increasing temperature.

  1. The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M.H.; Abelha, P.; Lapa, N.; Oliveira, J.S.; Cabrita, I.; Gulyurtlu, I. [INETI, Lisbon (Portugal)

    2003-07-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC with the aim of characterizating the ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials.

  2. Electrodialytic treatment for metal removal from sewage sludge ash from fluidized bed combustion

    DEFF Research Database (Denmark)

    Pazos, Marta; Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.

    2010-01-01

    Sewage sludge contains several potentially hazardous compounds such as heavy metals, PCBs, PAHs, etc. However, elements with high agricultural value (P, K or Ca) are also present. During the last years, the fluidized bed sludge combustor (FBSC) is considered an effective and novel alternative to ...

  3. The behavior of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Helena M.; Abelha, P.; Cabrita, I. [INETI-DEECA, Lisboa (Portugal); Lapa, N.; Oliveira, J.S. [UNL-Ubia, Monte de Caparica (Portugal)

    2003-07-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FRC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their reactor further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out, and the amount of unburned carbon leaving the combustor but captured in the cyclone was large enough to ensure substantial retention of mercury at low temperatures, and, hence, could contribute to an improvement of the mercury release, which still remains an issue of great concern to resolve during combustion of waste materials.

  4. The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed.

    Science.gov (United States)

    Helena Lopes, M; Abelha, P; Lapa, N; Oliveira, J S; Cabrita, I; Gulyurtlu, I

    2003-01-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials.

  5. The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed

    International Nuclear Information System (INIS)

    Helena Lopes, M.; Abelha, P.; Lapa, N.; Oliveira, J.S.; Cabrita, I.; Gulyurtlu, I.

    2003-01-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials

  6. Fluidized bed combustion of refuse-derived fuel in presence of protective coal ash

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, Eduardo [CIRCE, Universidad de Zaragoza, Maria de Luna, 3, Zaragoza (Spain); Aho, Martti [VTT Processes, P.O. Box 1603, 40101 Jyvaeskylae (Finland); Silvennoinen, Jaani; Nurminen, Riku-Ville [Kvaerner Power, P.O.Box 109, FIN-33101 Tampere (Finland)

    2005-12-15

    Combustion of refuse-derived fuel (RDF) alone or together with other biomass leads to superheater fouling and corrosion in efficient power plants (with high steam values) due to vaporization and condensation of alkali chlorides. In this study, means were found to raise the portion of RDF to 40% enb without risk to boilers. This was done by co-firing RDF with coal and optimizing coal quality. Free aluminum silicate in coal captured alkalies from vaporized alkali chlorides preventing Cl condensation to superheaters. Strong fouling and corrosion were simultaneously averted. Results from 100 kW and 4 MW CFB reactors are reported. (author)

  7. Assessment of the rice husk lean-combustion in a bubbling fluidized bed for the production of amorphous silica-rich ash

    International Nuclear Information System (INIS)

    Martinez, Juan Daniel; Pineda, Tatiana; Lopez, Juan Pablo; Betancur, Mariluz

    2011-01-01

    Rice husk lean-combustion in a bubbling and atmospheric fluidized bed reactor (FBR) of 0.3 m diameter with expansion to 0.4 m in the freeboard zone and 3 m height was investigated. Experiment design - response surface methodology (RSM) - is used to evaluate both excess air and normal fluidizing velocity influence (independent and controllable variables), in the combustion efficiency (carbon transformation), bed and freeboard temperature and silica content in the ashes. Hot gases emissions (CO 2 , CO and NO x ), crystallographic structure and morphology of the ash are also shown. A cold fluidization study is also presented. The values implemented in the equipment operation, excess air in the range of 40-125% and normal fluidization velocities (0.13-0.15 Nm/s) show that the values near the lower limit, encourage bed temperatures around 750 o C with higher carbon transformation efficiencies around 98%. However, this condition deteriorated the amorphous potential of silica present in the ash. An opposite behavior was evidenced at the upper limit of the excess air. This thermochemical process in this type of reactor shows the technical feasibility to valorize RH producing hot gases and an amorphous siliceous raw material.

  8. Stearic acid coating on circulating fluidized bed combustion fly ashes and its effect on the mechanical performance of polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Nina [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Ping, E-mail: pingzhang@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Song, Lixian; Kang, Ming; Lu, Zhongyuan [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Zheng, Rong [Sichuan Jinhe Group Co., Ltd., Mianyang 621010 (China)

    2013-08-15

    The aim of this work was to test circulating fluidized bed combustion fly ashes (CFAs) for its potential to be utilized in polymer composites manufacturing to improve its toughness. CFAs was coated by stearic acid and used in the composite of polypropylene/ethylene vinyl acetate/high density polyethylene (PP/EVA/HDPE) by molding process method. The resulting coated and uncoated CFAs were fully characterized by particle size analyzer, contact angles, powder X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stearic acid coated onto the surface of CFAs particles in the physical and chemical ways, and the total clad ratio reached 2.05% by measuring TGA/DTA curve. The percentage of CFAs particles focused to a narrow range 2–4 μm and the median mean size was 3.2 μm more than uncoated CFAs. The properties of hydrophobic and dispersive of CFAs particles improved and original activity was reserved after stearic acid coating. The stearic acid was verified as a coupling agent by how much effect it had on the mechanical properties. It showed the elongation at break of PP/EVA/HDPE reinforced with 15 wt% coated CFAs (c-CFAs) was 80.20% and higher than that of the uncoated. The stearic acid treatment of CFAs is a very promising approach to improve the mechanical strength due to the incorporation of stearic acid on the CFAs surface, and hence, further enhances the potential for recycling CFAs as a suitable filler material in polymer composites.

  9. Stearic acid coating on circulating fluidized bed combustion fly ashes and its effect on the mechanical performance of polymer composites

    International Nuclear Information System (INIS)

    Yao, Nina; Zhang, Ping; Song, Lixian; Kang, Ming; Lu, Zhongyuan; Zheng, Rong

    2013-01-01

    The aim of this work was to test circulating fluidized bed combustion fly ashes (CFAs) for its potential to be utilized in polymer composites manufacturing to improve its toughness. CFAs was coated by stearic acid and used in the composite of polypropylene/ethylene vinyl acetate/high density polyethylene (PP/EVA/HDPE) by molding process method. The resulting coated and uncoated CFAs were fully characterized by particle size analyzer, contact angles, powder X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stearic acid coated onto the surface of CFAs particles in the physical and chemical ways, and the total clad ratio reached 2.05% by measuring TGA/DTA curve. The percentage of CFAs particles focused to a narrow range 2–4 μm and the median mean size was 3.2 μm more than uncoated CFAs. The properties of hydrophobic and dispersive of CFAs particles improved and original activity was reserved after stearic acid coating. The stearic acid was verified as a coupling agent by how much effect it had on the mechanical properties. It showed the elongation at break of PP/EVA/HDPE reinforced with 15 wt% coated CFAs (c-CFAs) was 80.20% and higher than that of the uncoated. The stearic acid treatment of CFAs is a very promising approach to improve the mechanical strength due to the incorporation of stearic acid on the CFAs surface, and hence, further enhances the potential for recycling CFAs as a suitable filler material in polymer composites.

  10. SO3 Formation and the Effect of Fly Ash in a Bubbling Fluidised Bed under Oxy-Fuel Combustion Conditions.

    Czech Academy of Sciences Publication Activity Database

    Sarbassov, Y.; Duan, L.; Jeremiáš, Michal; Manovic, V.; Anthony, E.J.

    2017-01-01

    Roč. 167, DEC 1 (2017), s. 314-321 ISSN 0378-3820 Institutional support: RVO:67985858 Keywords : SO3 formation * oxy-fuel combustion * fluidised bed Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use OBOR OECD: Energy and fuels Impact factor: 3.752, year: 2016

  11. SO3 Formation and the Effect of Fly Ash in a Bubbling Fluidised Bed under Oxy-Fuel Combustion Conditions.

    Czech Academy of Sciences Publication Activity Database

    Sarbassov, Y.; Duan, L.; Jeremiáš, Michal; Manovic, V.; Anthony, E.J.

    2017-01-01

    Roč. 167, DEC 1 (2017), s. 314-321 ISSN 0378-3820 Institutional support: RVO:67985858 Keywords : SO3 formation * oxy- fuel combustion * fluidised bed Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use OBOR OECD: Energy and fuel s Impact factor: 3.752, year: 2016

  12. Fluidised bed combustion system

    International Nuclear Information System (INIS)

    McKenzie, E.C.

    1976-01-01

    Fluidized bed combustion systems that facilitates the maintenance of the depth of the bed are described. A discharge pipe projects upwardly into the bed so that bed material can flow into its upper end and escape downwardly. The end of the pipe is surrounded by an enclosure and air is discharged into the enclosure so that material will enter the pipe from within the enclosure and have been cooled in the enclosure by the air discharged into it. The walls of the enclosure may themselves be cooled

  13. Publication sites productive uses of combustion ash

    Science.gov (United States)

    Publication Sites Productive Uses of Combustion Ash For more information contact: e:mail: Public waste combustion ash in landfills. The new technology brief describes recent studies where ash was used

  14. Leaching from biomass combustion ash

    DEFF Research Database (Denmark)

    Maresca, Alberto; Astrup, Thomas Fruergaard

    2014-01-01

    The use of biomass combustion ashes for fertilizing and liming purposes has been widely addressed in scientific literature. Nevertheless, the content of potentially toxic compounds raises concerns for a possible contamination of the soil. During this study five ash samples generated at four...

  15. Characterisation of wood combustion ashes

    DEFF Research Database (Denmark)

    Maresca, Alberto

    The combustion of wood chips and wood pellets for the production of renewable energy in Denmark increased from 5.7 PJ to 16 PJ during the period 2000-2015, and further increases are expected to occur within the coming years. In 2012, about 22,300 tonnes of wood ashes were generated in Denmark....... Currently, these ashes are mainly landfilled, despite Danish legislation allowing their application onto forest and agricultural soils for fertilising and/or liming purposes. During this PhD work, 16 wood ash samples generated at ten different Danish combustion plants were collected and characterised...... for their composition and leaching properties. Despite the relatively large variations in the contents of nutrients and trace metals, the overall levels were comparable to typical ranges reported in the literature for other wood combustion ashes, as well as with regards to leaching. In general, the composition...

  16. Agglomeration of ash during combustion of peat and biomass in fluidized-bed reactors. Development of image analysis technique based on scanning electron microscopy; Tuhkan muuntuminen leijukerroskaasutuksessa ja -poltossa. Haitallisten hivenmetallien vapautuminen ja alkalien kaeyttaeytyminen

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E. [VTT Chemistry, Espoo (Finland); Arpiainen, V.; Jokiniemi, J. [VTT Energy, Espoo (Finland)] [and others

    1996-12-01

    The objective of the project is to study the behaviour of alkali metals (Na and K) and hazardous trace elements (Sb, As, Be, Cd, Cr, Co, Pb, Mn, Ni, Se and Zn) during fluidized bed combustion and gasification of solid fuels. The areas of interest are the release of elements studied from the bed and the behaviour of gaseous and particle-phase species after the release from the bed. During 1995 combustion and gasification experiments of Polish coal in bubbling bed were carried out with a laboratory scale fluidized bed gasifier in atmospheric pressure. Flue gas samples were drawn from the freeboard of the reactor and cooled quickly using a dilution probe. Ash particle size distributions were determined using low pressure impactors and differential mobility analyser. The morphology of the ash particles was studied with a scanning electron microscope (SEM) and will be further studied with transmission electron microscopy (TEM). The ash matrix elements (Si, Al, Fe, Ca and Mg) and the alkali metals (Na and K) were not significantly vaporized during the combustion process. More than 99 % of each of these elements was found in ash particles larger than 0.4 {mu}m. In Polish coal the alkali metals are bound mainly in silicates. The alkali metals were not released from the silicate minerals during the combustion process. A significant fraction of As, Cd and Pb was vaporized, released as gaseous species from the fuel particle and condensed mainly on the fine ash particles. 20 - 34 % of cadmium was present in fly ash particles smaller than 0.6 {mu}m (during combustion in 950 deg C), whereas only 1 % of the total ash was in this size fraction. All of the hazardous trace elements studied (As, Be, Cd, Co, Cr, Mn and Zn) were enriched in ash size fraction 0.6 - 5 {mu}m. The enrichment of Co, Cr, Mn, Ni, Pb and Sb was more significant during combustion in 950 deg C than in lower temperature (850 deg C)

  17. Fluidised-bed combustion of gasification residue

    Energy Technology Data Exchange (ETDEWEB)

    Korpela, T.; Kudjoi, A.; Hippinen, I.; Heinolainen, A.; Suominen, M.; Lu Yong [Helsinki Univ. of Technology (Finland). Lab of Energy Economics and Power Plant Engineering

    1996-12-01

    Partial gasification processes have been presented as possibilities for future power production. In the processes, the solid materials removed from a gasifier (i.e. fly ash and bed material) contain unburnt fuel and the fuel conversion is increased by burning this gasification residue either in an atmospheric or a pressurised fluidised-bed. In this project, which is a part of European JOULE 2 EXTENSION research programme, the main research objectives are the behaviour of calcium and sulphur compounds in solids and the emissions of sulphur dioxide and nitrogen oxides (NO{sub x} and N{sub 2}O) in pressurised fluidised-bed combustion of gasification residues. (author)

  18. Conversion of different ash content brown coal in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Osipov, P.; Chernyavskiy, N.; Ryzhkov, A.; Remenuk, A. [Ural Federal Univ., Ekaterinburg (Russian Federation). Dept. of Thermal Power Plants; Dulienko, S. [National Academy of Science of Ukraine, Kiev (Ukraine). Coal Energy Technology Inst.

    2013-07-01

    Available equations used to determine combustion specific rate of coal-derived cokes describe the burning of carbon particles well enough but are not accurate in case of ash-containing coke particles combustion. This study is an attempt to account for the influence of both initial ash content and its increase in the course of carbon conversion in specific rate calculations. The results of experimental study of burn-out dynamics of Volchanskiy field (North Urals) brown coal and its coke with different ash content under conditions of fluidized bed combustion at impulse-type non-gradient reactor RSC-1 and dynamic installation Pyrolysis-M are summarized. Diffusion and heterogeneous (kinetic) components of carbon combustion rate are identified separately by using diffusion and kinetics equation with correction for carbon mass fraction in particles. Burning particle overheating values and heterogeneous combustion rate constants at different temperatures are estimated.

  19. Utilization of coal ash from fluidized-bed combustion boilers as road base material; Sekitandaki ryudoso boiler kara no sekitanbai no robanzai to shite no riyo

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Y. [Kawasaki Heavy Industries, Ltd., Kobe (Japan); Kozasa, K. [Center for Coal Utilization, Japan, Tokyo (Japan); Tsuzura, K. [Naruto Salt Mfg. Co. Ltd., Tokushima (Japan); Izumi, H. [Nippon Hodo Co. Ltd., Tokyo (Japan)

    1998-03-01

    Coal ash from the fluidized bed boiler is evaluated for its properties as is, as solidified or granulated, and as the roadbed material. The coal ash tested in the experiment is a mixture of ash from the fluidized bed boiler bottom, ash from the cyclone separator, and ash from the bag filter. In the manufacture of solid or granulated bodies, coal ashes are kneaded in water whose amount puts the mixture near the plasticization limit, are pressed in a low-pressure press and made into solid bodies by a 15-hour curing in 60degC saturated steam, and the solid bodies are crushed into solid granules. A content release test is conducted about the release of dangerous substances, and road paving experiments are conducted to learn the workability and serviceability of the granulated material as a road paving material. A study of the experimental results discloses what is mentioned below. Coal ash containing 10-20vol% of CaO and 15vol% or less of unburnt carbon turns into a high-strength solid after curing in saturated steam whose temperature is not higher than 60degC. The granulated solid satisfies the standards that an upper subbase material is expected to satisfy. It also meets the environmental standards in a release content test for soil set forth by Environment Agency notification No.46. 8 refs., 8 figs., 4 tabs.

  20. Reduced ash related operational problems (slagging, bed agglomeration, corrosion and fouling) by co-combustion biomass with peat; Minskade askrelaterade driftsproblem (belaeggning, slaggning, hoegtemperatur-korrosion, baeddagglomerering) genom inblandning av torv i biobraenslen

    Energy Technology Data Exchange (ETDEWEB)

    Oehman, Marcus; Boman, Christoffer; Erhardsson, Thomas; Gilbe, Ram; Pommer, Linda; Bostroem, Dan; Nordin, Anders; Samuelsson, Robert; Burvall, Jan

    2006-12-15

    Combustion studies were performed in both a fluidized bed (5 kW) and in an under-feed pellets burner (20 kW) to elucidate the responsible mechanisms for the positive effects on ash related operational problems (i.e. slagging, fouling, corrosion and bed agglomeration) during co-combustion of several problematic biomass with peat. Three typical carex-containing Swedish peat samples with differences in e.g. silicon-, calcium- and sulfur contents were co-fired with logging residues, willow and straw in proportions corresponding to 15-40 weight %d.s. Mixing of corresponding 20 wt-% of peat significantly reduced the bed agglomeration tendencies for all fuels. The fuel specific agglomeration temperature were increased by 150-170 deg C when adding peat to the straw fuel and approximately 70-100 deg C when adding peat to the logging residue- and the willow fuel. The increased level of calcium in the inner bed particle layer caused by the added reactive calcium from the peat and/or removing alkali in the gas phase to a less reactive particular form via sorption and/or reaction with reactive peat ash (containing calcium, silica etc.) during which larger particles (>1{mu}m) are formed where collected potassium is present in a less reactive form, is considered to be the dominated reason for the increased agglomeration temperatures during combustion of logging residues and willow. During straw combustion, the ash forming matter were found as individual ash sticky particles in the bed. The iron, sulphur and calcium content of these individual ash particles were significantly increased when adding peat to the fuel mix thereby decreasing the stickiness of these particles i.e. reducing the agglomeration tendencies. Adding peat to the relatively silicon-poor fuels (willow and logging residues) resulted in higher slagging tendencies, especially when the relative silicon rich peat fuel (Brunnskoelen) was used. However, when co-combusting peat with the relatively silicon and potassium

  1. Bed agglomeration characteristics of palm shell and corncob combustion in fluidized bed

    International Nuclear Information System (INIS)

    Chaivatamaset, Pawin; Sricharoon, Panchan; Tia, Suvit

    2011-01-01

    Bed particle agglomeration was studied experimentally in an atmospheric laboratory scale fluidized bed combustor using quartz sand as bed material. Palm shell and corncob were tested. The objectives of the study were (i) to describe the contributions of the biomass ash properties and the operating conditions on the bed agglomeration tendency in term of the bed defluidization time (t def ) and the extent of potassium accumulation in the bed (K/Bed) and (ii) to further elucidate the ash inorganic behaviors and the governing bed agglomeration mechanisms. Defluidization caused by the bed agglomeration was experienced in all experiments during combustion of these biomasses, as a consequence of the presence of potassium in biomass. The experimental results indicated that biomass ash characteristics were the significant influence on the bed agglomeration. The increasing bed temperature, bed particle size and static bed height and the decreasing fluidizing air velocity enhanced the bed agglomeration tendency. The SEM/EDS analyses on the agglomerates confirmed that the agglomeration was attributed to the formation of potassium silicate liquid enriched on the surface of quartz sand particles in conjunction with the high surface temperature of the burning biomass char particles. Thermodynamic examination based on the phase diagram analysis confirmed that the molten phase formation was responsible for the agglomeration. In this study, the high molten ash fraction resulting from the high potassium content in biomass promoted the agglomeration and thus defluidization. - Highlights: → Palm shell and corncob of Thailand are tested their bed agglomeration behaviors during fluidized bed combustion. → The increase of bed temperature, bed particle size and static bed height and the decrease of air velocity enhance bed agglomeration. → The formation of ash derived potassium silicate melts enriched on sand surface is the key process. → The collision between char and sand

  2. Coal combustion ashes: A radioactive Waste?

    International Nuclear Information System (INIS)

    Michetti, F.P.; Tocci, M.

    1992-01-01

    The radioactive substances naturally hold in fossil fuels, such as Uranium and Thorium, after the combustion, are subjected to an increase of concentration in the residual combustion products as flying ashes or as firebox ashes. A significant percentage of the waste should be classified as radioactive waste, while the political strategies seems to be setted to declassify it as non-radioactive waste. (Author)

  3. Combustion of uraniferous lignites in fluidized bed

    International Nuclear Information System (INIS)

    Morales, G.; Gasos, P.

    1985-01-01

    In this paper a description of the continuous fluid bed combustion pilot plant unit, installed in the Junta de Energia Nuclear facilities, is presented. Besides, this paper deals with some of the studies carried out in the pilot plant aimed at the recovery of uranium from lignites, high in sulfur and ashes, coming from Calaf basin (Barcelona). These studies include the recovery of the heating value of these lignites and the reduction of environmental effect of SO 2 . Based on these studies an application exercise is presented. 9 references, 5 figures, 5 tables

  4. The characteristics of bed agglomeration during fluidized bed combustion of eucalyptus bark

    International Nuclear Information System (INIS)

    Chaivatamaset, Pawin; Tia, Suvit

    2015-01-01

    The bed agglomeration behaviors were investigated experimentally when eucalyptus bark was burning tested in a laboratory scale fluidized bed reactor. The focuses of this work were the influences of operating conditions and bed materials on the bed agglomeration tendency and the elucidation in the behaviors of fuel inorganic elements and the governing mode of the agglomeration. It was found that the defluidization caused by the bed agglomeration was clearly detectable from the decrease in measured bed pressure. The growth of bed particle and accumulation of agglomerates during combustion provided the partial to complete defluidization. The defluidization was promoted by the increase of bed temperature and bed particle size, and the decrease of fluidizing air velocity. The SEM-EDS analyses revealed that the bed agglomeration was mainly attributed to the formation of potassium silicate compounds as liquid phase during the combustion. This was initiated by the chemical reaction between the bed particle and the released ash constituents. In this study, the inorganic migration from fuel particle to bed particle was likely dominated by the condensation/reaction. The thermodynamic examination by ternary phase diagram analysis corroborated that the liquid phase formation of the ash derived materials controlled the agglomeration. The alumina sand prevented the bed agglomeration since it was inactive in the formation of viscous molten substances during combustion at the observed temperatures. - Highlights: • The behaviors of bed agglomeration were studied during the fluidized bed combustion of eucalyptus bark. • The increase in bed temperature and sand size, and the decrease of air velocity promoted bed defluidization. • The formation of molten potassium silicate compounds conduced to the bed agglomeration. • Condensation/reaction was the dominant inorganic migration mechanism from fuel particle to bed particle. • The alumina sand prevented effectively the bed

  5. Ash chemistry and behavior in advanced co-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M; Skrifvars, B J [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1997-10-01

    The purpose of this LIEKKI 2 project is to report results achieved within the EU/JOULE/OPTEB project to the Finnish combustion research community through the LIEKKI program. The purpose of the EU/JOULE/OPTEB project is to find prediction methods for evaluating ash behavior, such as slagging, fouling and corrosion propensity, in full scale combustion systems through chemical or mineralogical analyses, intelligent laboratory tests and chemistry calculations. The project focuses on coals, coal mixtures and coal biomass mixtures fired in advanced combustion systems, such as fluidized bed boilers, pulverized fuel boilers with critical steam values etc. The project will make use of (1) advanced multi-component combustion equilibrium calculations, (2) ash sintering tendency laboratory tests and (3) chemical evaluations of slagging, fouling and corrosion measurements in full scale units. (orig.)

  6. Co-combustion of tannery sludge in a commercial circulating fluidized bed boiler.

    Science.gov (United States)

    Dong, Hao; Jiang, Xuguang; Lv, Guojun; Chi, Yong; Yan, Jianhua

    2015-12-01

    Co-combusting hazardous wastes in existing fluidized bed combustors is an alternative to hazardous waste treatment facilities, in shortage in China. Tannery sludge is a kind of hazardous waste, considered fit for co-combusting with coal in fluidized bedboilers. In this work, co-combustion tests of tannery sludge and bituminous coal were conducted in a power plant in Jiaxing, Zhejiang province. Before that, the combustion behavior of tannery sludge and bituminous were studied by thermogravimetric analysis. Tannery sludge presented higher reactivity than bituminous coal. During the co-combustion tests, the emissions of harmful gases were monitored. The results showed that the pollutant emissions met the Chinese standard except for NOx. The Concentrations of seven trace elements (As, Cr, Cd, Ni, Cu, Pb, Mn) in three exit ash flows (bottom ash in bed, fly ash in filter, and submicrometer aerosol in flue gas) were analyzed. The results of mono-combustion of bituminous coal were compared with those of co-combustion with tannery sludge. It was found that chromium enriched in fly ash. At last, the leachability of fly ash and bottom ash was analyzed. The results showed that most species were almost equal to or below the limits except for As in bottom ashes and Cr in the fly ash of co-combustion test. The concentrations of Cr in leachates of co-combustion ashes are markedly higher than that of coal mono-combustion ashes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Combustion in fluidized bed reactors; Verbrennung in Wirbelschichtreaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Thome-Kozmiensky, Karl J. [vivis CONSULT GmbH, Nietwerder (Germany)

    2013-03-01

    Since the first application for the coal gasification, the fluidized bed technology has passed an impressive development. Nowadays, the fluidized bed technology is utilized at chemical processes, drying and cooling, gasification, combustion and purification of exhaust gas. In the firing technology, the fluidized technology initially has been proved in the combustion of very high ash coal and sewage sludge. Recently, the fluidized bed technology also is applied in the drying of sewage sludge, combustion of domestic waste - as in Japan and Sweden - as well as in the gasification and combustion of substitute fuels, biomass - wood pellets, wood chips, straw, cocoa shells and so forth - and residues from the paper manufacturing - such as in Germany and Austria. Under this aspect, the author of the contribution under consideration reports on the combustion of sewage sludge, substitute fuels and biomass.

  8. A Comparative Study of Fouling and Bottom Ash from Woody Biomass Combustion in a Fixed-Bed Small-Scale Boiler and Evaluation of the Analytical Techniques Used

    Directory of Open Access Journals (Sweden)

    Lara Febrero

    2015-05-01

    Full Text Available In this work, fouling and bottom ash were collected from a low-power boiler after wood pellet combustion and studied using several analytical techniques to characterize and compare samples from different areas and determine the suitability of the analysis techniques employed. TGA results indicated that the fouling contained a high amount of organic matter (70%. The XRF and SEM-EDS measurements revealed that Ca and K are the main inorganic elements and exhibit clear tendency in the content of Cl that is negligible in the bottom ash and increased as it penetrated into the innermost layers of the fouling. Calcite, magnesia and silica appeared as the major crystalline phases in all the samples. However, the bottom ash was primarily comprised of calcium silicates. The KCl behaved identically to the Cl, preferably appeared in the adhered fouling samples. This salt, which has a low melting point, condenses upon contact with the low temperature tube and played a crucial role in the early stages of fouling formation. XRD was the most useful technique applied, which provided a semi-quantitative determination of the crystalline phases. FTIR was proven to be inadequate for this type of sample. The XRF and SEM-EDS, techniques yield similar results despite being entirely different.

  9. Ash behaviour in fluidized bed gasification and combustion: release of harmful trace elements and the behavior of alkalis; Tuhkan muuntuminen leijukerroskaasutuksessa ja -poltossa: Haitallisten hivenmetallien vapautuminen ja alkalien kaeyttaeytyminen

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E; Valmari, T [VTT Chemical Technology, Espoo (Finland)

    1997-10-01

    During 1996 the behaviour of alkaline metals (K and Na) during circulating fluidized bed combustion of forest residue was studied in a real-scale plant using aerosol measurement instruments (filters, impactor, DMA). Prior to heat exchangers (850 deg C) the ash mass-concentration was 1.0 - 1.3 g/Nm{sup 3} with 1 % of ash forming constituents as vapours. At least 98 % of sulphur, over 90 % of sodium and over 80 % of potassium were found in particulate phase prior to heat exchangers. On the other hand, at least 80 % of the chlorine was in vapour phase. 98 % of the ash was in coarse (> 0.3 {mu}m) particles. Coarse ash particles had an irregular surface structure often consisting of fine primary particles. The remaining 2 % was observed in fine particles of about 0.1 {mu}m. Both rounded and cornered (suggesting crystal structure) fine particles were found. The fine particles were composed of alkali chlorides and sulphates, mainly of KCl. About 80 % of the ash on mass basis was deposited onto heat exchanger surfaces when soot-blowing was not carried out. Practically all of the particles larger than 10 {mu}m were deposited. The deposition was less significant for smaller particles. The fine particle concentration before and after the heat exchangers was the same within the experimental inaccuracy. The deposited fraction of potassium, sodium and sulphur was about the same than that of the total ash: However, the deposition of chlorine was much lower since the chlorine content was low in the coarse particles that were deposited most effectively. (orig.)

  10. Carbon Shale Combustion in the Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Olek Małgorzata

    2014-06-01

    Full Text Available The purpose of this article is to present the possibilities of coal shale combustion in furnaces with bubbling fluidized bed. Coal shale can be autothermally combusted in the fluidized bed, despite the low calorie value and high ash content of fuel. Established concentrations of CO (500 ppm and VOC (30 mg/m3 have indicated a high conversion degree of combustible material during combustion process. Average concentrations of SO2 and NOx in the flue gas were higher than this received from the combustion of high quality hard coal, 600 ppm and 500 ppm, respectively. Optional reduction of SO2 and NOx emission may require the installation of flue gas desulphurization and de-NOx systems.

  11. Fluidized bed and pulverized coal combustion residues for secondary pavements

    International Nuclear Information System (INIS)

    Ghafoori, N.; Diawara, H.; Wang, L.

    2009-01-01

    The United States produced nearly 125 million tons of coal combustion products in 2006. These by-products include fly ash, flue gas desulphurization materials, bottom ash, boiler slag, and other power plant by-products. The expense associated with waste disposal, lack of disposal sites, and significant environmental damage linked with the disposal of coal combustion residues have encouraged innovative utilization strategies such as the fluidized bed combustion (FBC) unit. This paper presented the results of a laboratory investigation that examined the properties of composites developed with different proportions of pre-conditioned FBC spent bed, pulverized coal combustion fly ash, natural fine aggregate, and Portland cement. The purpose of the study was to examine the extent to which the by-product composites could replace currently used materials in secondary roads. The paper presented the research objectives and experimental programs, including matrix constituent and proportions; mixture proportions; and mixing, curing, sampling, and testing. The discussion of results centered around compressive strength and expansion by internal sulfate attack. It was concluded that with proper proportioning, by-products of pulverized and fluidized bed combustion promote binding of sand particles and provide adequate strength under various curing and moisture conditions 4 refs., 6 tabs.

  12. Column leaching from biomass combustion ashes

    DEFF Research Database (Denmark)

    Maresca, Alberto; Astrup, Thomas Fruergaard

    2015-01-01

    The utilization of biomass combustion ashes for forest soil liming and fertilizing has been addressed in literature. Though, a deep understanding of the ash chemical composition and leaching behavior is necessary to predict potential benefits and environmental risks related to this practice....... In this study, a fly ash sample from an operating Danish power plant based on wood biomass was collected, chemically characterized and investigated for its leaching release of nutrients and heavy metals. A column leaching test was employed. The strongly alkaline pH of all the collected eluates suggested...

  13. Pulsed atmospheric fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  14. Characterization of residues from waste combustion in fluidized bed boilers. Evaluation report

    International Nuclear Information System (INIS)

    Hagman, U.; Elander, P.

    1996-04-01

    In this report a thorough characterization of the solid residues from municipal solid waste combustion in a Kvaerner EnviroPower bubbling fluidized bed boiler in Lidkoeping, is presented. Three different end products are generated, namely bottom ash, cyclone ash, and filter ash. The bottom ash, consisting of bed ash and hopper ash, is screened and useful bed material recycled. In the characterization, also the primary constituents bed ash and hopper ash have been included. A chemical characterization have been performed including total inorganic contents, content of unburnt matter, leaching behaviour (availability tests, column tests, pH-static tests) and leaching tests according to certain standards for classification (AFX31-210, DIN38414, TCLP). Physical characterization have included grain size distribution, grain density, compaction properties and stabilization of cyclone ash with subsequent testing of comprehensive strength and saturated hydraulic conductivity. From an environmental point of view, the quality of the bottom ash and probably the cyclone ash from fluidized bed combustion as determined in this study, indicate a potential for utilization. Utilization of the bottom ash could be accepted in certain countries, e.g. France, according to their current limit values. In other countries, e.g. Sweden, no general limit values are given and utilization have to be applied for in each case. The judgement is then based, not only on total contents in the residue and its leaching behaviour, but also on the specific environmental conditions at the site. 7 refs, 17 figs, 12 tabs

  15. Staged fluidized-bed combustion and filter system

    International Nuclear Information System (INIS)

    Mei, J.S.; Halow, J.S.

    1994-01-01

    A staged fluidized-bed combustion and filter system are described for substantially reducing the quantity of waste through the complete combustion into ash-type solids and gaseous products. The device has two fluidized-bed portions, the first primarily as a combustor/pyrolyzer bed, and the second as a combustor/filter bed. The two portions each have internal baffles to define stages so that material moving therein as fluidized beds travel in an extended route through those stages. Fluidization and movement is achieved by the introduction of gases into each stage through a directional nozzle. Gases produced in the combustor/pyrolyzer bed are permitted to travel into corresponding stages of the combustor/filter bed through screen filters that permit gas flow but inhibit solids flow. Any catalyst used in the combustor/filter bed is recycled. The two beds share a common wall to minimize total volume of the system. A slightly modified embodiment can be used for hot gas desulfurization and sorbent regeneration. Either side-by-side rectangular beds or concentric beds can be used. The system is particularly suited to the processing of radioactive and chemically hazardous waste. 10 figures

  16. Flue Gas Emissions from Fluidized Bed Combustion

    NARCIS (Netherlands)

    Bramer, E.A.; Valk, M.

    1995-01-01

    During the past decades fluidized bed coal combustion was developed as a technology for burning coal in an effective way meeting the standards for pollution control. During the earlier years of research on fluidized bed combustion, the potential for limiting the S02 emission by adding limestone to

  17. Characterisation of ashes produced by co-combustion of recovered fuels and peat

    Energy Technology Data Exchange (ETDEWEB)

    Frankenhaeuser, M. [Borealis Polymers Oy, Porvoo (Finland)

    1997-10-01

    The current project focuses on eventual changes in ash characteristics during co-combustion of refuse derived fuel with coal, peat, wood or bark, which could lead to slagging, fouling and corrosion in the boiler. Ashes were produced at fluidised bed (FB) combustion conditions in the 15 kW reactor at VTT Energy, Jyvaeskylae, the fly ash captured by the cyclone was further analysed by XRF at Outokumpu Geotechnical Laboratory, Outokumpu. The sintering behaviour of these ashes was investigated using a test procedure developed at the Combustion Chemistry Research Group at Aabo Akademi University. The current extended programme includes a Danish refuse-derived fuel (RDF), co-combusted with bark/coal (5 tests) and wood/coal (2 tests), a RF from Jyvaskyla (2 tests with peat/coal) and de-inking sludges co- combusted at full-scale with wood waste or paper mill sludge (4 ashes provided by IVO Power). Ash pellets were thermally treated in nitrogen in order to avoid residual carbon combustion. The results obtained show no sintering tendencies below 600 deg C, significant changes in sintering are seen with pellets treated at 1000 deg C. Ash from 100 % RDF combustion does not sinter, 25 % RDF co-combustion with wood and peat, respectively, gives an insignificant effect. The most severe sintering occurs during co-combustion of RDF with bark. Contrary to the earlier hypothesis a 25 % coal addition seems to have a negative effect on all fuel blends. Analysis of the sintering results versus ash chemical composition shows, that (again), in general, an increased level of alkali chlorides and sulphates gives increased sintering. Finally, some results on sintering tendency measurements on ashes from full-scale CFB co-combustion of deinking sludge with wood waste and paper mill sludge are given. This shows that these ashes show very little, if any, sintering tendency, which can be explained from ash chemistry

  18. Experimental studies on pulp and paper mill sludge ash behavior in fluidized bed combustors

    Energy Technology Data Exchange (ETDEWEB)

    Latva-Somppi, J. [VTT Chemical Technology, Espoo (Finland). Process Technology

    1998-11-01

    Ash formation during the fluidized bed combustion (FBC) of pulp and paper mill sludges has been experimentally studied on an industrial and bench scale. The methods included aerosol measurements, chemical and crystalline composition analyses, thermogravimetry and electron microscopy. Fly ash mass and number size distributions and elemental enrichment in submicron particles and bottom ash were measured. Fly ash, bottom ash and ash deposits were characterized and their formation mechanisms are discussed. During combustion the fine paper-making additives in sludge, clay minerals and calcite, sintered fanning porous agglomerates. The fly ash mass mean size was 7.5 - 15 lam and the supermicron particles included 93.6 - 97.3 % of the fly ash. Condensation of the volatilized inorganic species formed spherical submicron particles in the fly ash. Their mass concentration was almost negligible when co-firing paper mill sludges and wood. This suggests that the fraction of the volatilized inorganic species in the paper mill sludges was low. Results from pulp mill sludge and bark co-firing were different. A clear mass mode below 0.3 pm, presenting 2.2 - 5.0 weight-% of the fly ash was detected. The condensed species included K, Na, S and Cl. Their mass fraction was higher in the pulp mill sludge than in the paper mill sludge. Evidently this resulted in increased volatilization and formation of condensed particles. The following trace elements were enriched in the submicron ash during pulp mill sludge and wood co-firing: As, Cd, Rb and Pb. The main part of the volatile species was, however, captured in the bulk ash. Presumably, this was due to the high surface area concentration in the bulk ash. Sludge moisture was observed to reduce the inorganic species volatilization. Probably steam vaporization from the wet sludge through the burning layer decreased combustion temperatures on char surface and less char was produced. Hence, the volatilization of ash forming species was

  19. Fluidized bed combustion with the use of Greek solid fuels

    Directory of Open Access Journals (Sweden)

    Kakaras Emmanuel

    2003-01-01

    Full Text Available The paper is an overview of the results obtained up to date from the combustion and co-combustion activities with Greek brown coal in different installations, both in semi-industrial and laboratory scale. Combustion tests with Greek lignite were realized in three different Circulating Fluidized Bed Combustion (CFBC facilities. Low rank lignite was burned in a pilot scale facility of approx. 100kW thermal capacity, located in Athens (NTUA and a semi-industrial scale of 1.2 MW thermal capacity, located at RWE's power station Niederaussem in Germany. Co-combustion tests with Greek xylitic lignite and waste wood were carried out in the 1 MWth CFBC installation of AE&E, in Austria. Lab-scale co-combustion tests of Greek pre-dried lignite with biomass were accomplished in a bubbling fluidized bed in order to investigate ash melting problems. The obtained results of all aforementioned activities showed that fluidized bed is the appropriate combustion technology to efficiently exploit the low quality Greek brown coal either alone or in conjunction with biomass species.

  20. Co-combustion of waste materials using fluidized bed technology

    Energy Technology Data Exchange (ETDEWEB)

    M. Lopes; I. Gulyurtlu; P. Abelha; T. Crujeira; D. Boavida; I. Cabrita [INETI-DEECA, Lisbon (Portugal)

    2004-07-01

    There is growing interest in using renewable fuels in order to sustain the CO{sub 2} accumulation. Several waste materials can be used as coal substitutes as long as they contain significant combustible matter, as for example MSW and sewage sludge. Besides the outcome of the energetic valorization of such materials, combustion must be regarded as a pre-treatment process, contributing to the safe management of wastes. Landfilling is an expensive management option and requires a previous destruction of the organic matter present in residues, since its degradation generates greenhouse gases and produces acidic organic leachates. Fluidized bed combustion is a promising technology for the use of mixtures of coal and combustible wastes. This paper presents INETI's experience in the co-combustion of coal with this kind of residues performed in a pilot fluidized bed. Both the RDF (from MSW and sewage sludge) and sewage sludge combustion problems were addressed, relating the gaseous emissions, the behaviour of metals and the leachability of ashes and a comparison was made between co-combustion and mono-combustion in order to verify the influence of the utilization of coal. 9 refs., 1 fig., 3 tabs.

  1. Electrodialytic removal of Cd from biomass combustion fly ash suspensions

    DEFF Research Database (Denmark)

    Kirkelund, Gunvor M.; Ottosen, Lisbeth M.; Damoe, Anne J.

    2013-01-01

    was investigated with the aim of enabling reuse of the ashes. The ashes originated from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. A series of laboratory scale electrodialytic remediation experiments were conducted with each ash. The initial Cd...

  2. Combustion of poultry litter in a fluidised bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    P. Abelha; I. Gulyurtlu; D. Boavida; J. Seabra Barros; I. Cabrita; J. Leahy; B. Kelleher; M. Leahy [DEECA-INETI, Lisbon (Portugal)

    2003-04-01

    Combustion studies of poultry litter alone or mixed with peat by 50% on weight basis were undertaken in an atmospheric bubbling fluidised bed. Because of high moisture content of poultry litter, there was some uncertainty whether the combustion could be sustained on 100% poultry litter and as peat is very available in Ireland, its presence was considered to help to improve the combustion. However, the results showed that, as long as the moisture content of poultry litter was kept below 25%, the combustion did not need the addition of peat. The main parameters that were investigated are (i) moisture content, (ii) air staging, and (iii) variations in excess air levels along the freeboard. The main conclusions of the results are (i) combustion was influenced very much by the conditions of the fuel supply, (ii) the steady fuel supply was strongly dependent on the moisture content of the poultry litter, (iii) temperature appeared to be still very influential in reducing the levels of unburned carbon and hydrocarbons released from residues, (iv) the air staging in the freeboard improved combustion efficiency by enhancing the combustion of volatiles released from residues in the riser and (vi) NOx emissions were influenced by air staging in the freeboard. Particles collected from the bed and the two cyclones were analysed to determine the levels of heavy metals and the leachability tests were carried out with ashes collected to verify whether or not they could safely be used in agricultural lands. 8 refs., 1 fig., 8 tabs.

  3. Behavior of heavy metals during fluidized bed combustion of poultry litter

    OpenAIRE

    Lynch, Deirdre; Low, Fiona; Henihan, Anne Marie; Garcia, Alberto; Kwapinski, Witold; Zhang, Lian; Leahy, J.J.

    2014-01-01

    peer-reviewed In this study, we have examined the behavior of heavy metals during fluidized bed combustion of poultry litter. Heavy metals examined include As, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, V, and Zn. Solid and gaseous streams were analyzed and compared with relevant guidelines to determine the potential environmental impact of combustion and subsequent land spreading or landfill of the resulting ash. The majority of heavy metals were associated with the solid ash fraction, with low ...

  4. Co-combustion of anthracite coal and wood pellets: Thermodynamic analysis, combustion efficiency, pollutant emissions and ash slagging.

    Science.gov (United States)

    Guo, Feihong; Zhong, Zhaoping

    2018-08-01

    This work presents studies on the co-combustion of anthracite coal and wood pellets in fluidized bed. Prior to the fluidized bed combustion, thermogravimetric analysis are performed to investigate the thermodynamic behavior of coal and wood pellets. The results show that the thermal decomposition of blends is divided into four stages. The co-firing of coal and wood pellets can promote the combustion reaction and reduce the emission of gaseous pollutants, such as SO 2 and NO. It is important to choose the proportion of wood pellets during co-combustion due to the low combustion efficiency caused by large pellets with poor fluidization. Wood pellets can inhibit the volatilization of trace elements, especially for Cr, Ni and V. In addition, the slagging ratio of wood pellets ash is reduced by co-firing with coal. The research on combustion of coal and wood pellets is of great significance in engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Agglomeration mechanism in biomass fluidized bed combustion – Reaction between potassium carbonate and silica sand

    DEFF Research Database (Denmark)

    Anicic, Bozidar; Lin, Weigang; Dam-Johansen, Kim

    2018-01-01

    Agglomeration is one of the operational problems in fluidized bed combustion of biomass, which is caused by interaction between bed materials (e.g. silica sand) and the biomass ash with a high content of potassium species. However, the contribution of different potassium species to agglomeration ...

  6. Pressurized Fluidized Bed Combustion of Sewage Sludge

    Science.gov (United States)

    Suzuki, Yoshizo; Nojima, Tomoyuki; Kakuta, Akihiko; Moritomi, Hiroshi

    A conceptual design of an energy recovering system from sewage sludge was proposed. This system consists of a pressurized fluidized bed combustor, a gas turbine, and a heat exchanger for preheating of combustion air. Thermal efficiency was estimated roughly as 10-25%. In order to know the combustion characteristics of the sewage sludge under the elevated pressure condition, combustion tests of the dry and wet sewage sludge were carried out by using laboratory scale pressurized fluidized bed combustors. Combustibility of the sewage sludge was good enough and almost complete combustion was achieved in the combustion of the actual wet sludge. CO emission and NOx emission were marvelously low especially during the combustion of wet sewage sludge regardless of high volatile and nitrogen content of the sewage sludge. However, nitrous oxide (N2O) emission was very high. Hence, almost all nitrogen oxides were emitted as the form of N2O. From these combustion tests, we judged combustion of the sewage sludge with the pressurized fluidized bed combustor is suitable, and the conceptual design of the power generation system is available.

  7. An SEM/EDX study of bed agglomerates formed during fluidized bed combustion of three biomass fuels

    International Nuclear Information System (INIS)

    Scala, Fabrizio; Chirone, Riccardo

    2008-01-01

    The agglomeration behaviour of three biomass fuels (exhausted and virgin olive husk and pine seed shells) during fluidized bed combustion in a lab-scale reactor was studied by means of SEM/EDX analysis of bed agglomerate samples. The effect of the fuel ash composition, bed temperature and sand particle size on agglomeration was investigated. The study was focused on the main fuel ash components and on their interaction with the bed sand particles. Agglomeration was favoured by high temperature, small sand size, a high fraction of K and Na and a low fraction of Ca and Mg in the fuel ash. An initial fuel ash composition close to the low-melting point eutectic composition appears to enhance agglomeration. The agglomerates examined by SEM showed a hollow structure, with an internal region enriched in K and Na where extensive melting is evident and an external one where sand particles are only attached by a limited number of fused necks. Non-molten or partially molten ash structures deposited on the sand surface and enriched in Ca and Mg were also observed. These results support an ash deposition-melting mechanism: the ash released by burning char particles inside the agglomerates is quantitatively deposited on the sand surface and then gradually embedded in the melt. The low-melting point compounds in the ash migrate towards the sand surface enriching the outermost layer, while the ash structure is progressively depleted of these compounds

  8. The study of partitioning of heavy metals during fluidized bed combustion of sewage sludge and coal

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, I.; Lopes, M.H.; Abelha, P.; Cabrita, I.; Oliveira, J.F.S. [INETI, Lisbon (Portugal)

    2006-06-15

    The behavior of Cd, Cr, Cu, Co, Mn, Ni, Pb, Zn, and Hg during the combustion tests of a dry granular sewage sludge on a fluidized bed combustor pilot (FBC) of about 0.3 MW was evaluated. The emissions of these heavy metals from mono-combustion were compared with those of co-combustion of the sludge with a bituminous coal. The effect of the addition of limestone was also studied in order to retain sulphur compounds and to verify its influence on the retention of heavy metals (HM). Heavy metals were collected and analyzed from different locations of the installation, which included the stack, the two cyclones, and the material removed from the bed. The results showed that the volatility of metals was rather low, resulting in emissions below the legal limits of the new directive on incineration, with the exception of Hg during the mono-combustion tests. The partitioning of metals, except for Hg, appeared to follow that of ashes, amounting to levels above 90% in the bed streams in the mono-combustion case. For co-combustion, there was a lower fixation of HM in the bed ashes, mostly originating essentially from the sewage sludge, ranging between 40% and 80%. It is believed that in this latter case, a slightly higher temperature could have enhanced the volatilization, especially of Cd and Pb. However these metals were then retained in fly ashes captured in the cyclones. In the case of Hg, the volatilisation was complete. The bed ashes were free of Hg and part of Hg was retained in the cyclones and the rest was emitted either with fine ash particles or in gaseous forms. In mono-combustion the Hg emissions from the stack (particles and gas) accounted, for about 50%. This appeared to have significantly decreased in the case of co-combustion, as only about 75% has been emitted, due to the retention effect of cyclone ashes.

  9. The study of partitioning of heavy metals during fluidized bed combustion of sewage sludge and coal

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, Ibrahim; Lopes, M. Helena; Abelha, Pedro; Cabrita, Isabel; Oliveira, J.F. Santos

    2003-07-01

    The behaviour of Cd, Cr, Cu, Co, Mn, Pb, Zn and Hg during the combustion tests of granular dry sewage sludges on a pilot FBC of about 0,3 MW was evaluated. The emissions of these heavy metals from mono-combustion were compared with those of co-combustion of the sludge with a bituminous coal. The effect of the addition of limestone was also studied in order to retain sulphur compounds and to verify its influence on the retention of heavy metals. Heavy metals were collected and analysed from different locations of the installation, which included the stack, the two cyclones and the material removed from the bed. The results showed that the volatility of metals was rather low, resulting in emissions below the legal limits of the new directive on incineration, with the exception of Hg during the mono-combustion tests. The partitioning of metals, except for Hg, appeared to follow that of ashes, amounting to levels above 90% in the bed streams in the mono-combustion case. For co-combustion, there was a lower fixation of HM in the bed ashes, mostly originating essentially from the sewage sludge, ranging between 40 and 80%. It is believed that in this latter case, a slightly higher bed temperature could have enhanced the volatilisation, especially of Cd and Pb. However these metals were then retained in cyclone ashes. In the case of Hg, the volatilisation was complete. The bed ashes were free of Hg and part of it was retained in the cyclone and emitted as both fine ash particles and in gaseous forms. In mono-combustion the Hg emissions from the stack (particles and gas) accounted for about 50%, although there was a significant amount unaccounted for. This appeared to have significantly decreased in the case of co-combustion, as only about 15% has been emitted, due to the retention effect of cyclone ashes which presented high quantities of unburned carton and possibly condensed sulphur species.

  10. Coal-char combustion in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mehrotra, S.P.; Pande, M. [Indian Institute of Technolgy, Kanpur (India)

    2001-12-01

    Combustion of bituminous coal chars ranging from 0.8 mm to 1.8 mm has been studied in a fluidised bed reactor at temperatures ranging from 500 to 850{sup o}C. The fluidised bed consists of inert sand particles of average size of 0.5 mm and reactive coal char particles. A heat balance has been worked out to calculate the rate of combustion of char from measured incremental changes in the bed temperature during combustion. Investigations on partially burnt particles suggest that the ash layer which builds up around the burning core of char particles is non-flaking and the particles burn in a shrinking core manner. Analysis of rate data indicates that the rate of combustion is controlled by chemical reaction kinetics, though diffusion of oxygen through the bundary layer begins to influence the overall reaction kinetics at higher temperatures. The burnt out time varies linearly with particle size. Activation energy for the chemical reaction control regime is found to be around 68 kJ/mole.

  11. Quantification of fusion in ashes from solid fuel combustion

    DEFF Research Database (Denmark)

    Hansen, Lone Aslaug; Frandsen, Flemming; Dam-Johansen, Kim

    1999-01-01

    The fusion of ashes produced during solid fuel combustion greatly affects the tendency of these ashes to cause operational problems in utility boilers. In this paper, a new and quantitative laboratory method for assessing the fusion of ashes based on simultaneous thermal analysis, STA, is described...

  12. Electrodialytic removal of Cd from biomass combustion fly ash

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Ottosen, Lisbeth M.; Simonsen, Peter

    2004-01-01

    Due to a high concentration of Cd, biomass combustion fly ash often fails to meet the Danish legislative requirements for recycling on agricultural fields. In this work the potential of using the method Electrodialytic Remediation to reduce the concentration of Cd in different biomass combustion....... The initial Cd concentration in the ashes varied between 8.8 mg Cd/kg DM (co-firing ash) and 64 mg Cd/kg DM (pre-washed straw ash), and pH varied from 3.7 to 13.3. In spite of large differences in ash characteristics, the electrodialytic remediation experiments indicated a good remediation potential for all...... four ashes. Final Cd concentrations below 2.0 mg Cd/kg were reached in all ashes within 14 days of remediation and legislative requirements were met. After further optimization of the remediation process on the pre-washed straw ash, limiting concentrations were reached after only 48 hours...

  13. Sludge combustion in fluidized bed reactors at laboratory scale

    International Nuclear Information System (INIS)

    Chirone, R.; Cammarota, A.

    2001-01-01

    The combustion of a dried sewage sludge in laboratory scale fluidized bed has been studied in Naples by the Istituto di ricerche sulla combustione (Irc) in the framework of a National project named Thermal Process with Energy Recovery to be used in laboratory and pre-pilot scale apparatus. The attention has been focused on emissions of unreacted carbon as elutriated fines, on the emissions of pollutant gases and on the assessment of the inventory of fly- and bottom ashes. The combustion behaviour of sewage sludge has been compared with those of a market available Tyre Derived Fuel (TDF) and a biomass from Mediterranean area (Robinia Pseudoacacia) and with that of a South African bituminous coal. Stationary combustion tests were carried out at 850 0 C by feeding particles in the size range 0-1 mm into a bed of silica sand without any sorbent addition. The fluidized bed combustor has been operated, at a superficial gas velocity of 0.4 m/s and different excesses of air ranging between 14 and 98%. Relatively high combustion efficiency, larger than 98.9% has been obtained in experiments carried out with sewage sludge and excess of air larger than 20%. These values, are comparable with those obtained in previously experimental activity carried out under similar operative conditions with a South Africa Bituminous coal (97-98%). It is larger than those obtained by using a Tyre Derived Fuel (89-90%) and the Robinia Pseudoacacia Biomass (93-93%). The relative importance of carbon fines elutriation, CO emissions and volatile bypassing the bed in determining the loss of combustion efficiency has been evaluated for the different fuels tested [it

  14. Bioenergy originating from biomass combustion in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Crujeira, T.; Gulyurtlu, I.; Lopes, H.; Abelha, P.; Cabrita, I. [INETI/DEECA, Lisboa (Portugal)

    2008-07-01

    Bioenergy could significantly contribute to reducing and controlling greenhouse emissions (GHG) and to replace fossil fuels in large power plants. Although the use of biomass, originating from forests, could be beneficial, particularly in preventing fires, there are obstacles to achieve a sustainable supply chain of biomass in most European countries. In addition, there are also technical barriers as requirements of biomass combustion may differ from those of coal, which could mean significant retrofitting of existing installations. The combustion behaviour of different biomass materials were studied on a pilot fluidised bed combustor, equipped with two cyclones for particulate matter removal. The gaseous pollutants leaving the stack were sampled under isokinetic conditions for particulate matter, chlorine compounds, heavy metals and dioxins and furans (PCDD/F). The results obtained indicated that the combustion of these materials did not present any operational problem, although for temperatures above 800{sup o}C, bed agglomeration could be observed for all biomass materials studied. Most of the combustion of biomass, contrary to what is observed for coal, takes place in the riser where the temperature was as much as 150{sup o}C above that of the bed. Stable combustion conditions were achieved as well as high combustion efficiency. When compared with the emissions of bituminous coal, the most used fossil fuel, the emissions of CO and SO2 were found to be lower and NOx emissions were similar to those of coal. HCl and PCDD/F could be considerable with biomasses containing high chlorine levels, as in the case of straw. It was observed that the nature of ash could give rise serious operating problems.

  15. Improvement of Combustion Characteristics in Fluidized Bed

    International Nuclear Information System (INIS)

    Mohamed, H.S.; El Sourougy, M.R.; Faik, M.

    2009-01-01

    The present investigation is directed towards the experimental study of the effect of a new design of the bed temperature on the overall thermal efficiency and heat transfer by conduction, convection and radiation in gaseous fuel-fluidized bed combustion system. The experiments are performed on a water-cooled fluidized bed model furnace with cylindrical cross-section of 0.25 m diameter and its height is 0.60 m. the fluidising medium used is sand particles with average diameter 1.5 mm. The bed temperature is varied between 700 degree C and 1100 degree C. Measurements f carbon dioxide, carbon monoxide and oxygen concentrations are carried out by using water-cooled sampling probe, and infrared and paramagnetic analyzers. The results obtained show that the bed temperature, the total heat transfer to the wall and the bed combustion efficiency increase with the decrease of the air-fuel ratio. It is also found that 91% of the total heat transfer is in the fluidising part of the bed and most of this heat is transferred by convection from hot sand particles to the wall. Two empirical formulae for the calculation of the wall heat transfer coefficient and the particle convective heat transfer coefficient are proposed. A verification of the proposed empirical formulae is made by comparing the calculated values with the experimental results.

  16. Managing ash from the combustion of solid waste

    International Nuclear Information System (INIS)

    Hauser, R.

    1992-01-01

    This paper reports that with millions of tons of refuse being combusted each year, increasing concern over the environment impact of the residue produced has caused both regulators and the resource recovery industry to address the technical and regulatory issues relating to the safe handling and disposal of ash. The basic issue concerning solid waste combustion ash management in this country is how, based on past, recent, and ongoing scientific research, solid waste combustion ash should be handled. Typically, refuse contains approximately 20 to 25 percent residue, which is collected either on grates at the bottom of the combustion chamber or filtered from the exhaust gases by the air pollution control equipment. The fly ash component of the total residue stream is between 10 and 30 percent of the total residue while the bottom ash content ranges from 70 to 90 percent of the total weight, depending upon the air pollution control equipment utilized, especially acid gas scrubbing equipment

  17. Environmental remediation with products of fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A.G.

    1999-07-01

    Commercialization of fluidized bed combustion (FBC) technology could be enhanced by increased utilization of FBC products (ash). In the US, coal combustion products (CCP) are not hazardous under RCRA and are regulated as residual waste by the states. The composition of CCP from fluidized beds is primarily determined by the inorganic constituents in coal, the sorbent reaction products and the unreacted sorbent. The combustion system and the inclusion of other fuels may also affect the chemical composition, physical properties and leaching behavior. The alkalinity of the FBC material, residual lime and pozzolanic properties are desirable characteristics for use in soil stabilization and mine reclamation. At reclaimed surface coal mines, placement of CCP is intended to reduce the amount of acid mine drainage (AMD) produced at such sites. Neutralization, inhibition of acid forming bacteria, encapsulation of the pyrite or water diversion are believed to be the mechanisms facilitated by the alkaline material. Comparison of water quality, before and after injection of a grout composed of FBC ash and water indicated small increases in pH and decreases in acidity at discharge points. The concentrations of calcium and magnesium in water samples generally increased compared to background levels. The average concentration of trace elements (arsenic, cobalt, copper, nickel and zinc) was slightly elevated in the injection areas, but in down dip and discharge water samples were comparable to background levels. Over a four year period, the average acidity in the injected area decreased by approximately 30%, a value similar to another site where a mixture of class F fly ash and cement was injected. Although coal mine remediation is a beneficial environmental use of FBC products, its effectiveness may be related to the amount of FBCB used and the method of emplacement.

  18. Environmental remediation with products of fluidized bed combustion

    International Nuclear Information System (INIS)

    Kim, A.G.

    1999-01-01

    Commercialization of fluidized bed combustion (FBC) technology could be enhanced by increased utilization of FBC products (ash). In the US, coal combustion products (CCP) are not hazardous under RCRA and are regulated as residual waste by the states. The composition of CCP from fluidized beds is primarily determined by the inorganic constituents in coal, the sorbent reaction products and the unreacted sorbent. The combustion system and the inclusion of other fuels may also affect the chemical composition, physical properties and leaching behavior. The alkalinity of the FBC material, residual lime and pozzolanic properties are desirable characteristics for use in soil stabilization and mine reclamation. At reclaimed surface coal mines, placement of CCP is intended to reduce the amount of acid mine drainage (AMD) produced at such sites. Neutralization, inhibition of acid forming bacteria, encapsulation of the pyrite or water diversion are believed to be the mechanisms facilitated by the alkaline material. Comparison of water quality, before and after injection of a grout composed of FBC ash and water indicated small increases in pH and decreases in acidity at discharge points. The concentrations of calcium and magnesium in water samples generally increased compared to background levels. The average concentration of trace elements (arsenic, cobalt, copper, nickel and zinc) was slightly elevated in the injection areas, but in down dip and discharge water samples were comparable to background levels. Over a four year period, the average acidity in the injected area decreased by approximately 30%, a value similar to another site where a mixture of class F fly ash and cement was injected. Although coal mine remediation is a beneficial environmental use of FBC products, its effectiveness may be related to the amount of FBCB used and the method of emplacement

  19. Fluidized bed combustion: mixing and pollutant limitation

    Energy Technology Data Exchange (ETDEWEB)

    Leckner, B. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Energy Conversion

    1997-10-01

    Fluidized bed combustion (FBC) has been applied commercially during a few decades, and sufficient knowledge is gained to design boilers with sizes of up to several hundreds of megawatt thermal power (MW{sub th}). The knowledge of what goes on inside a large combustion chamber is still limited, however, and this impedes further optimization and efficient solution of problems that might occur. Despite this lack of knowledge the present survey deals with combustion chamber processes and discusses mixing and distribution of fuel and air in the combustion chamber and its importance for sulphur capture and reduction of emissions of nitrogen oxides. It is desirable to present the material in a general way and to cover the entire field of FBC. However, the scarce openly published information deals mostly with coal combustion in atmospheric circulating fluidized bed (CFB) combustors, and therefore this application will receive most attention, but reference is also made to pressurized combustion and to other fuels than coal. In this context the important work made in the LIEKKI project on the analysis of different fuels and on the influence of pressure should be especially pointed out. (orig.)

  20. Synthetic aggregates from combustion ashes using an innovative rotary kiln.

    Science.gov (United States)

    Wainwright, P J; Cresswell, D J

    2001-01-01

    This paper describes the use of a number of different combustion ashes to manufacture synthetic aggregates using an innovative rotary 'Trefoil' kiln. Three types of combustion ash were used, namely: incinerated sewage sludge ash (ISSA); municipal solid waste incinerator bottom ash (MSWIBA-- referred to here as BA); and pulverised fuel ash (Pfa). The fine waste ash fractions listed above were combined with a binder to create a plastic mix that was capable of being formed into 'green pellets'. These pellets were then fired in a Trefoil kiln to sinter the ashes into hard fused aggregates that were then tested for use as a replacement for the natural coarse aggregate in concrete. Results up to 28 days showed that these synthetic aggregates were capable of producing concretes with compressive strengths ranging from 33 to 51 MPa, equivalent to between 73 and 112% of that of the control concrete made with natural aggregates.

  1. Electrodialytic removal of cadmium from straw combustion fly ash

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Ottosen, Lisbeth M.; Villumsen, Arne

    2004-01-01

    Fly ash from straw combustion contains valuable nutrients when returned to agricultural soils. In many instances, however, this fly ash may contain heavy metals, such as cadmium, at levels which often exceed the limits given by the Danish legislation. Thus before utilizing the nutrients, cadmium...... must be removed from these ashes. The use of an electrodialytic remediation method to remove cadmium from fly ash arising from straw combustion and containing 11.2 mg Cd kg$+-1$/ DM (dry matter) was accessed. After 36 days of remediation at a constant current density of 5.6 mA cm$+-2$/ more than 97...

  2. The influence of fine char particles burnout on bed agglomeration during the fluidized bed combustion of a biomass fuel

    Energy Technology Data Exchange (ETDEWEB)

    Scala, Fabrizio; Chirone, Riccardo [Istituto di Ricerche sulla Combustione, CNR, P.le V. Tecchio, 80-80125 Naples (Italy); Salatino, Piero [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, P.le V. Tecchio, 80-80125 Naples (Italy)

    2003-11-15

    The combustion of biomass char in a bubbling fluidized bed is hereby addressed, with specific reference to the influence that the combustion of fine char particles may exert on ash deposition and bed agglomeration phenomena. Experiments of steady fluidized bed combustion (FBC) of powdered biomass were carried out with the aim of mimicking the postcombustion of attrited char fines generated in the fluidized bed combustion of coarse char. Experimental results showed that the char elutriation rate is much smaller than expected on the basis of the average size of the biomass powder and of the carbon loading in the combustor. Samples of bed material collected after prolonged operation of the combustor were characterized by scanning electron microscopy (SEM)-EDX analysis and revealed the formation of relatively coarse sand-ash-carbon aggregates. The phenomenology is consistent with the establishment of a char phase attached to the bed material as a consequence of adhesion of char fines onto the sand particles. Combustion under sound-assisted fluidization conditions was also tested. As expected, enhancement of fines adhesion on bed material and further reduction of the elutriation rate were observed. Experimental results are interpreted in the light of a simple model which accounts for elutriation of free fines, adhesion of free fines onto bed material and detachment of attached fines by attrition of char-sand aggregates. Combustion of both free and attached char fines is considered. The parameters of the model are assessed on the basis of the measured carbon loadings and elutriation rates. Model computations are directed to estimate the effective size and the peak temperature of char-sand aggregates. The theoretical estimates of the effective aggregate size match fairly well those observed in the experiments.

  3. Field study of wastes from fluidized-bed combustion technologies

    International Nuclear Information System (INIS)

    Weinberg, A.; Holcombe, L.; Butler, R.

    1991-01-01

    The Department of Energy (DOE) has undertaken a research project to monitor advanced coal process wastes placed in natural geologic settings. The overall objective of the study is to gather field data on the engineering and environmental performance of disposed solid waste from various advanced coal processes. The coal ash from a fluidized-bed combustion unit is being studied as part of the DOE program. The unit is a 110-MW circulating fluidized bed (CFB) at Colorado Ute Electric Association's Nucla Steam Electric Station, which is being demonstrated with the support of the DOE Clean Coal Technology Program. The Electric Power Research Institute is cofunding the study. In June of 1989, a test cell approximately 100 feet square and 8 feet deep was constructed and filled with ash from the Colorado Ute CFB unit. The cell was instrumented with lysimeters and neutron probe access tubes to monitor water flow and leachate chemistry in the ash; groundwater wells and runoff collection devices were installed to determine the effects on groundwater and surface water quality, and a meteorological station was installed to determine the water balance. Additionally, tests are being performed to evaluate the chemical, physical, and mineralogical properties of the solid waste and geologic materials. Results from the first year of monitoring are presented

  4. Fluidized bed combustion of low-grade coal and wastes: Research and development

    Energy Technology Data Exchange (ETDEWEB)

    Borodulya, V.A.; Dikalenko, V.I.; Palchonok, G.I.; Vinogradov, L.M. [Academy of Sciences of Belarus, Minsk (Belarus). A.V. Luikov Heat and Mass Transfer Inst.; Dobkin, S.M.; Telegin, E.M. [Special Design Office, Brest (Belarus)

    1994-12-31

    Experimental studies were carried out to investigate devolatilization of fuel as single spherical particles of wood, hydrolytic lignin, leather sewage sludge and Belarussian brown coals in a fluidized bed of sand. It is found that the devolatilization process depends on moisture and ash contents in fuel and on the external heat and mass transfer rate. The char combustion occurs largely in the intermediate region. Kinetic parameters of the devolatilization and char combustion are obtained. A low-capacity fluidized bed boiler suitable for combustion of coal and different wastes is described.

  5. Furnace for degasification and gasification of combustibles rich in ashes

    Energy Technology Data Exchange (ETDEWEB)

    1952-05-13

    A furnace is described for the degasification and the gasification of combustibles rich in ashes with continuous-functioning vertical chambers of transversal rectangular sections in which the washing gas flows from one side to the other, traversing the combustible, characterized by the fact that the height of the combustible surrounded by the washing gas stays in a proportion higher than 10:1 to the thickness of the width of combustible.

  6. Application of Fly Ash from Solid Fuel Combustion in Concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard

    2008-01-01

    with implementation of low-NOx combustion technologies. The present thesis concerns three areas of importance within this field: 1) testing of fly ash adsorption behavior; 2) the influence of fuel type and combustion conditions on the ash adsorption behaviour including full-scale experiments at the power plant...... has a low sensitivity toward small variations in AEA adsorption between different fly ashes and it requires further work before a finished procedure is accomplished. Finally, it was shown that changes in temperature affect both test methods. Pulverized fuel has been combusted in an entrained flow...... formation. It was found that the AEA adsorption of the fly ash was reduced up to five times compared to reference operation, when the plant was operated with minimum furnace air staging, three levels of burners instead of four and without recycled flue gas. The lower AEA requirements of the fly ash...

  7. Utilization of ash from municipal solid waste combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jones, C.; Hahn, J.; Magee, B.; Yuen, N.; Sandefur, K.; Tom, J.; Yap, C.

    1999-09-01

    This ash study investigated the beneficial use of municipal waste combustion combined ash from the H-POWER facility in Oahu. These uses were grouped into intermediate cover for final closure of the Waipahu landfill, daily cover at the Waimanalo Gulch Landfill, and partial replacement for aggregate in asphalt for road paving. All proposed uses examine combined fly and bottom ash from a modern waste-to-energy facility that meets requirements of the Clean Air Act Amendments for Maximum Achievable Control Technology.

  8. Leaching of Nutrient Salts from Fly Ash from Biomass Combustion

    DEFF Research Database (Denmark)

    Thomsen, Kaj; Vu, Duc Thuong; Stenby, Mette

    2005-01-01

    Methods to selectively leach nutrient salts from fly ash, while leaving cadmium un-dissolved were studied. Temperature, pH, water to fly ash ratio are all expected to influence the kinetics and the equilibrium boundaries for this process. Three different leaching methods were investigated....... The first method was a counter current moving bed process in four stages. The ash was kept in filter bags and leached with water that was introduced into the bags at 40-50°C. In the second method, fly ash and water was brought into contact in a partially fluidized bed. The third method was a counter current...... moving bed process with agitation/centrifugation. It was found that a satisfactory leaching of the nutrient salts could be achieved with the third method using only two or three stages, depending on the water to fly ash ratio. It is an advantage to perform the process at temperatures above 50°C...

  9. Fundamental study of low-NOx combustion fly ash utilization

    International Nuclear Information System (INIS)

    Suuberg, Eric M.; Hurt, Robert H.

    1998-01-01

    This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over fifty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives

  10. Trace elements partitioning during coal combustion in fluidized bed under O{sub 2}/CO{sub 2} atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haixin; Zhao, Changsui; Liang, Cai; Duan, Lunbo; Chen, Huichao [Southeast Univ., Nanjing (China). School of Energy and Environment

    2013-07-01

    Experiments were conducted to investigate the effects of temperature and O{sub 2}/CO{sub 2} atmosphere on trace elements (Cr, Mn, Co, Ni, Cd, Pb, Hg, As, Se) partitioning during combustion of Xuzhou bituminous coal in a 6 kWth fluidized bed. Inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectrometry (AFS) were used to determine trace elements contents in raw coal, bottom ash, fly ash and flue gas. The results indicate that with bed temperature increase, the relative enrichment of all the trace elements except Cr in bottom ash decreases suggesting that their volatility is enhanced. The relative enrichments of hardly volatile elements, like Cr and Mn in fly ash increase with bed temperature increase while those of partially volatile and highly volatile elements in fly ash are opposite. The relative enrichments of trace elements except Cr and Mn in fly ash are higher than those in bottom ash. Increasing bed temperature promotes elements like As, Se and Hg to migrate to vapor phase, Mn to migrate to fly ash and Cr to migrate to both bottom ash and fly ash. 21%O{sub 2}/79%CO{sub 2} atmosphere improves the volatility of Cr, Mn, Co, Se and their migration to fly ash, while restrains the volatility of As, Ni, Pb. It has little effect on the volatility of Hg but improves its migration to fly ash. Mass balance ratio was also calculated to observe trace elements distribution in bottom ash, fly ash and flue gas. There is no much difference in trace elements distribution between the two atmospheres. It can be seen that the trace elements proportion in fly ash is much greater, and more than 40% of Hg is distributed in the gas phase. Most of Hg and Se volatilize during combustion. The mass balance ratios are 87 {proportional_to} 129% which is considered acceptable.

  11. Biofuel Combustion Fly Ash Influence on the Properties of Concrete

    Directory of Open Access Journals (Sweden)

    Aurelijus Daugėla

    2016-02-01

    Full Text Available Cement as the binding agent in the production of concrete can be replaced with active mineral admixtures. Biofuel combustion fly ash is one of such admixtures. Materials used for the study: Portland cement CEM I 42.5 R, sand of 0/4 fraction, gravel of 4/16 fraction, biofuel fly ash, superplasticizer, water. Six compositions of concrete were designed by replacing 0%, 5%, 10%, 15% 20%, and 25% of cement with biofuel fly ash. The article analyses the effect of biofuel fly ash content on the properties of concrete. The tests revealed that the increase of biofuel fly ash content up to 20% increases concrete density and compressive strength after 7 and 28 days of curing and decreases water absorption, with corrected water content by using plasticizing admixture. It was found that concrete where 20% of cement is replaced by biofuel ash has higher frost resistance.

  12. Recovered fuels - The connection between fuel preparation, combustion equipments and ash quality; Returbraenslen - kopplingen mellan braensleberedning, foerbraenningsutrustning och askkvalitet

    Energy Technology Data Exchange (ETDEWEB)

    Gyllenhammar, Marianne; Johansson, Inge [S.E.P. Scandinavian Energy Project AB, Goeteborg (Sweden)

    2004-01-01

    The lack of bio fuel and new regulations of waste treatment have increased the interest of recovered fuels. Co-combustion is of great interest, but the consequences and permit handling involved in introducing a new fuel into a plant have to be investigated. The aim of this study is to see if it is possible to affect the ash quality by pre-treatment of the fuel, or by firing in different combustion equipments. Ashes can be used in several different types of applications. Few of these have uniform requirements of ash quality. The ongoing research will hopefully help generating unified regulations and recommendations for the uses of ashes. However, right now the knowledge is limited and very specific. Every type of ash has to be analysed for the appropriate use. It is especially the requirements of leaching that are difficult to make general. The work started with a survey of recovered fuels. It contains roughly which fuels exist and which of those are accessible for the energy market in Sweden. The survey showed that there are approximately 13 Mton/y wastes partly accessible to the energy market; 50 % are used for material recycling, 32 % for energy recovery, 1.5 % for composting and the rest are used as landfill. Three recovered fuels were chosen and studied more thoroughly. These were PTP (paper, wood and plastic), tires and impregnated wood. The project showed that the recovered fuels have different qualifications as fuels and have different possibilities at co-combustion which results in variable ash quality. A pre-treated fuel is more homogeneous which give better combustion and cleaner ashes. A fluidised bed demands a more pre-treated fuel than a grate and the fluidised bed generate more ashes because the ashes contain bed material. As a result of this the ashes from a fluidised bed is generally easier to utilize. In this project the composition of ashes from co-combustion of the three recovered fuels together with wood fuel has been estimated. The aim was to

  13. Pulsed atmospheric fluidized bed combustion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  14. Sulphation of oil shale ash under atmospheric and pressurized combustion conditions

    International Nuclear Information System (INIS)

    Kuelaots, I.; Yrjas, P.; Hupa, M.; Ots, A.

    1995-01-01

    One of the main problems in conventional combustion boilers firing pulverized oil shale is the corrosion and fouling of heating surfaces, which is caused by sulphur compounds. Another major problem, from the environmental point of view, are the high SO 2 emissions. Consequently, the amount of sulphur in flue gases must be reduced. One alternative to lower the SO 2 , concentration is the use of new technologies, such as pressurized fluidized bed combustion (PFBC). In FBC processes, the sulphur components are usually removed by the addition of limestone (CaCO 3 ) or dolomite (CaCO 3 x MgCO 3 ) into the bed. The calcium in these absorbents react with SO 2 , producing solid CaSO 4 . However, when burning oil shale, there would be no need to add limestone or dolomite into the bed, due to the initially high limestone content in the fuel (molar ratio Ca/S =10). The capture of sulphur by oil shale ashes has been studied using a pressurized thermogravimetric apparatus (PTGA). The chosen experimental conditions were typical for atmospheric and pressurized fluidized bed combustion. Four different materials were tested - one cyclone ash from an Estonian oil shale boiler, two size fractions of Estonian oil shale and, one fraction of Israeli oil shale. The cyclone ash was found to be the poorest sulphur absorbent. In general, the results from the sulphur capture experiments under both atmospheric and pressurized fluidized bed conditions showed that the oil shale can capture not only its own sulphur but also significant amounts of additional sulphur from another fuel if the fuels are mixed together. (author)

  15. CIRCULATING MOVING BED COMBUSTION PROOF OF CONCEPT

    Energy Technology Data Exchange (ETDEWEB)

    Jukkola, Glen

    2010-06-30

    Circulating Moving Bed (CMB) combustion technology has its roots in traditional circulating fluidized bed technology and involves a novel method of solid fuel combustion and heat transfer. CMB technology represents a step change in improved performance and cost relative to conventional PC and FBC boilers. The CMB heat exchanger preheats the energy cycle working fluid, steam or air, to the high temperature levels required in systems for advanced power generation. Unique features of the CMB are the reduction of the heat transfer surfaces by about 60% as a result of the enhanced heat transfer rates, flexibility of operation, and about 30% lower cost over existing technology. The CMB Phase I project ran from July 2001 through March 2003. Its objective was to continue development of the CMB technology with a series of proof of concept tests. The tests were conducted at a scale that provided design data for scale up to a demonstration plant. These objectives were met by conducting a series of experiments in ALSTOM Power’s Multi-use Test Facility (MTF). The MTF was modified to operate under CMB conditions of commercial interest. The objective of the tests were to evaluate gas-to-solids heat transfer in the upper furnace, assess agglomeration in the high temperature CMB bubbling bed, and evaluate solids-to-tube heat transfer in the moving bed heat exchanger. The Phase I program results showed that there are still some significant technical uncertainties that needed to be resolved before the technology can be confidently scaled up for a successful demonstration plant design. Work remained in three primary areas: • scale up of gas to solid heat transfer • high temperature finned surface design • the overall requirements of mechanical and process design. The CMB Phase II workscope built upon the results of Phase I and specifically addressed the remaining technical uncertainties. It included a scaled MTF heat transfer test to provide the necessary data to scale up gas

  16. Boiler for combustion fuel in a fluidized bed

    Directory of Open Access Journals (Sweden)

    Laković Mirjana S.

    2015-01-01

    Full Text Available Fuel combustion in fluidized bed combustion is a process that is current and which every day gives more attention and there are many studies that have been closely associated with this technology. This combustion technology is widespread and constantly improving the range of benefits it provides primarily due to reduced emissions. This paper presents the boilers for combustion in a fluidized bed, whit characteristics and advantages. Also is shown the development of this type of boilers in Republic of Serbia. In this paper is explained the concept of fluidized bed combustion. Boilers for this type of combustion can be improved and thereby increase their efficiency level. More detailed characteristics are given for boilers with bubbling and circulating fluidized bed as well as their mutual comparison.

  17. Removal of metallic ions from aqueous solutions by fluidized bed fly ashes

    Energy Technology Data Exchange (ETDEWEB)

    Rio, S.; Delebarre, A.; Hequet, V. [Ecole des Mines de Nantes, 44 - Nantes (France); Blondin, J. [Cerchar 62 - Mazingarbe (France)

    2001-07-01

    One of the main constraints deriving from the generation of power by coal combustion is to find some use for the fly ashes instead of disposing of them. Fly ashes from two fluidized bed power plants were tested to remove Pb{sup 2+}, Cu{sup 2+}, Cr (III), Ni{sup 2+}, Zn{sup 2+} and Cr (VI) from aqueous solutions. Experimental design methodology was used to study the removal and the leaching as a function of (i) the water pollutant content, (ii) the metal concentration in water, (iii) the pH of the solution and (iv) the addition of lime to fly ashes. The results show that the percentage of adsorbed ions was more important when they were in contact with silico-aluminous fly ashes than sulfo-calcic fly ashes, except in the case of the ion Ni{sup 2+}. The removal of metallic ions increases with increasing pH. The metallic canons removal accounting for the leaching test was higher when lime was added to silico-aluminous fly ashes during the adsorption. (authors)

  18. Sulfur retention by ash during coal combustion. Part I. A model of char particle combustion

    Directory of Open Access Journals (Sweden)

    BORISLAV GRUBOR

    2003-02-01

    Full Text Available A model for the combustion of porous char particles as a basis for modeling the process of sulfur retention by ash during coal combustion is developed in this paper. The model belongs to the microscopic intrinsic models and describes the dynamic behavior of a porous char particle during comustion, taking into account temporal and spatial changes of all important physical properties of the char particle and various combustion parameters. The parametric analysis of the enhanced model shows that the model represents a good basis for the development of a model for the process of sulfur retention by ash during coal combustion. The model enables the prediction of the values of all parameters necessary for the introduction of reactions between sulfur compounds and mineral components in ash, primarily calcium oxide.

  19. Fluidized-bed calciner with combustion nozzle and shroud

    International Nuclear Information System (INIS)

    Wielang, J.A.; Palmer, W.B.; Kerr, W.B.

    1977-01-01

    A nozzle employed as a burner within a fluidized bed is coaxially enclosed within a tubular shroud that extends beyond the nozzle length into the fluidized bed. The open-ended shroud portion beyond the nozzle end provides an antechamber for mixture and combustion of atomized fuel with an oxygen-containing gas. The arrangement provides improved combustion efficiency and excludes bed particles from the high-velocity, high-temperature portions of the flame to reduce particle attrition. 4 claims, 2 figures

  20. Update on status of fluidized-bed combustion technology

    International Nuclear Information System (INIS)

    Stallings, J.; Boyd, T.; Brown, R.

    1992-01-01

    During the 1980s, fluidized-bed combustion technology has become the dominant technology for solid-fuel-fired power generation systems in the United States. Atmospheric fluidized beds as large as 160 MWe in capacity are now in operation, while pressurized systems reaching 80 MWe have started up in the last year. The commercial status, boiler performance, emissions, and future developments for both atmospheric and pressurized fluidized-bed combustion systems are discussed

  1. Combustion characteristics and retention-emission of selenium during co-firing of torrefied biomass and its blends with high ash coal.

    Science.gov (United States)

    Ullah, Habib; Liu, Guijian; Yousaf, Balal; Ali, Muhammad Ubaid; Abbas, Qumber; Zhou, Chuncai

    2017-12-01

    The combustion characteristics, kinetic analysis and selenium retention-emission behavior during co-combustion of high ash coal (HAC) with pine wood (PW) biomass and torrefied pine wood (TPW) were investigated through a combination of thermogravimetric analysis (TGA) and laboratory-based circulating fluidized bed combustion experiment. Improved ignition behavior and thermal reactivity of HAC were observed through the addition of a suitable proportion of biomass and torrefied. During combustion of blends, higher values of relative enrichment factors in fly ash revealed the maximum content of condensing volatile selenium on fly ash particles, and depleted level in bottom ash. Selenium emission in blends decreased by the increasing ratio of both PW and TPW. Higher reductions in the total Se volatilization were found for HAC/TPW than individual HAC sample, recommending that TPW have the best potential of selenium retention. The interaction amongst selenium and fly ash particles may cause the retention of selenium. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Management methods ash from combustion of biomass. Review of productions and associated methods. Extended abstract

    International Nuclear Information System (INIS)

    Boulday, D.; Marcovecchio, F.

    2016-02-01

    The study deals with the management of biomass ashes from industrial and collective facilities (wood log excluded) and provides a state of the art, in France and in Europe, flows, methods of recovery and post-treatment, physico-chemical characteristics and programs for new opportunities. Currently, flows of biomass ash are estimated at 110 kt-330 kt in France and 1 500 kt - 4 500 kt in Europe and should amount respectively 330 kt-1000 kt and 3100 kt-8000 kt in 2020. The physical and chemical composition of biomass ash is influenced by many factors: fuel, pretreatment, post-treatment, additives, fly and bottom ash, power installation, type of combustion equipment, extraction mode...However, these ashes have characteristics which are commonly accepted: liming / neutralizing power, fertilizer, pozzolanic behavior generally almost zero. In France and Europe, a distinction is made between fly and bottom ashes, usually less polluted. However, this separation does not always make sense according to the valuation mode, the type of equipment (including fluidized bed or grid) or mixtures of ash made in the plant (e.g. mix of bottom and coarse ash). Currently, the main outlet is ash landfill, followed by agricultural and forestry recycling. The other identified opportunities concern a few countries and marginal flows: brick-works, road engineering... The development of biomass energy, coupled with a reduction in landfill options, has given rise to many research and demonstration programs in recent years, particularly in France, with some promising solutions. Many limiting factors, which can be different according to opportunities, have been identified. More or less advanced solutions aimed at reducing the harmful effects of these factors (slaking lime, sorting, grinding...).However to date, the most robust and massive solution for ash recycling material remains undoubtedly the agricultural recycling. According to the study, it's necessary to consolidate the agricultural

  3. Atmospheric Fluidized Bed Combustion testing of North Dakota lignite

    Energy Technology Data Exchange (ETDEWEB)

    Goblirsch, G; Vander Molen, R H; Wilson, K; Hajicek, D

    1980-05-01

    The sulfur retention by the inherent alkali, and added limestone sorbent, perform about the same and are reasonably predictable within a range of about +-10% retention by application of alkali to sulfur ratio. Temperature has a substantial effect on the retention of sulfur by the inherent alkali or limestone. The temperature effect is not yet fully understood but it appears to be different for different coals and operational conditions. The emission of SO/sub 2/ from the fluid bed burning the Beulah lignite sample used for these tests can be controlled to meet or better the current emission standards. The injection of limestone to an alkali-to-sulfur molar ratio of 1.5 to 1, should lower the SO/sub 2/ emissions below the current requirement of 0.6 lb SO/sub 2//10/sup 6/ Btu to 0.4 lb SO/sub 2//10/sup 6/ Btu, a safe 33% below the standard. Agglomeration of bed material, and consequent loss of fluidization quality can be a problem when burning high sodium lignite in a silica bed. There appears, however, to be several ways of controlling the problem including the injection of calcium compounds, and careful control of operating conditions. The heat transfer coefficients measured in the CPC and GFETC tests are comparable to data obtained by other researchers, and agree reasonably well with empirical conditions. The NO/sub x/ emissions measured in all of the tests on Beulah lignite are below the current New Source Performance Standard of 0.5 lb NO/sub 2//10/sup 6/ Btu input. Combustion efficiencies for the Beulah lignite are generally quite high when ash recycle is being used. Efficiencies in the range of 98% to 99%+ have been measured in all tests using this fuel.

  4. A new method to quantify fluidized bed agglomeration in the combustion of biomass fuels

    Energy Technology Data Exchange (ETDEWEB)

    Oehman, M. [Umeaa Univ. (Sweden). Dept. of Chemistry

    1997-12-31

    The present licentiate thesis is a summary and discussion of four papers, dealing with the development, evaluation and use of a new method to quantify bed agglomeration tendencies for biomass fuels. An increased utilization of biomass related fuels has many environmental benefits, but also requires careful studies of potential new problems associated with these fuels such as bed agglomeration/defluidization during combustion and gasification in fluidized beds. From a thorough literature survey, no suitable methods to determine bed agglomeration tendencies of different fuels, fuel combinations or fuels with additives appeared to be available. It therefore seemed of considerable interest to develop a new method for the quantification of fluidized bed agglomeration tendencies for different fuels. A bench scale fluidized bed reactor (5 kW), specially designed to obtain a homogeneous isothermal bed temperature, is used. The method is based on controlled increase of the bed temperature by applying external heat to the primary air and to the bed section walls. The initial agglomeration temperature is determined by on- or off-line principal component analysis of the variations in measured bed temperatures and differential pressures. Samples of ash and bed material for evaluation of agglomeration mechanisms may also be collected throughout the operation. To determine potential effects of all the process related variables on the determined fuel specific bed agglomeration temperature, an extensive sensitivity analysis was performed according to a statistical experimental design. The results showed that the process variables had only relatively small effects on the agglomeration temperature, which could be determined to 899 deg C with a reproducibility of {+-} 5 deg C (STD). The inaccuracy was determined to be {+-} 30 deg C (STD). The method was also used to study the mechanism of both bed agglomeration using two biomass fuels and prevention of bed agglomeration by co-combustion

  5. Emission performance and combustion efficiency of a conical fluidized-bed combustor firing various biomass fuels

    International Nuclear Information System (INIS)

    Permchart, W.; Kouprianov, V.I.

    2004-01-01

    This paper summarizes the results of an experimental study on combustion of three distinct biomass fuels (sawdust, rice husk and pre-dried sugar cane bagasse) in a single fluidized-bed combustor (FBC) with a conical bed using silica sand as the inert bed material. Temperature, CO, NO and O 2 concentrations along the combustor height as well as in flue (stack) gas were measured in the experimental tests. The effects of fuel properties and operating conditions (load and excess air) on these variables were investigated. Both CO and NO axial profiles were found to have a maximum whose location divides conventionally the combustor volume into formation (lower) and reduction (upper) regions for these pollutants. Based on CO emission and unburned carbon content in fly ash, the combustion efficiency of the conical FBC was quantified for the selected biomass fuels fired under different operating conditions. (Author)

  6. Ultrafine ash aerosols from coal combustion: Characterization and health effects

    Energy Technology Data Exchange (ETDEWEB)

    William P. Linak; Jong-Ik Yoo; Shirley J. Wasson; Weiyan Zhu; Jost O.L. Wendt; Frank E. Huggins; Yuanzhi Chen; Naresh Shah; Gerald P. Huffman; M. Ian Gilmour [US Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Laboratory

    2007-07-01

    Ultrafine coal fly-ash particles withdiameters less than 0.5 {mu}m typically comprise less than 1% of the total fly-ash mass. This paper reports research focused on both characterization and health effects of primary ultrafine coal ash aerosols alone. Ultrafine, fine, and coarse ash particles were segregated and collected from a coal burned in a 20 kW laboratory combustor and two additional coals burned in an externally heated drop tube furnace. Extracted samples from both combustors were characterized by transmission electron microscopy (TEM), wavelength dispersive X-ray fluorescence(WD-XRF) spectroscopy, Moessbauer spectroscopy, and X-ray absorption fine structure (XAFS) spectroscopy. Pulmonary inflammation was characterized by albumin concentrations in mouse lung lavage fluid after instillation of collected particles in saline solutions and a single direct inhalation exposure. Results indicate that coal ultrafine ash sometimes contains significant amounts of carbon, probably soot originating from coal tar volatiles, depending on coal type and combustion device. Surprisingly, XAFS results revealed the presence of chromium and thiophenic sulfur in the ultrafine ash particles. The instillation results suggested potential lung injury, the severity of which could be correlated with the carbon (soot) content of the ultrafines. This increased toxicity is consistent with theories in which the presence of carbon mediates transition metal (i.e., Fe) complexes, as revealed in this work by TEM and XAFS spectroscopy, promoting reactive oxygenspecies, oxidation-reduction cycling, and oxidative stress. 24 refs., 7 figs.

  7. Combustion and co-combustion of biomass in a bubbling fluidized bed boiler

    NARCIS (Netherlands)

    Khan, A.A.

    2007-01-01

    This PhD dissertation concerns the study of different aspects of biomass (co)-combustion in small-scale fluidized bed boilers for heat generation. The most renowned gaseous emissions from fluidized bed combustion, namely, CO and NO, are investigated with the help of experimental and theoretical

  8. Numerical modeling of straw combustion in a fixed bed

    DEFF Research Database (Denmark)

    Zhou, Haosheng; Jensen, Anker; Glarborg, Peter

    2005-01-01

    . The straw combustion processes include moisture evaporation, straw pyrolysis, gas combustion, and char combustion. The model provides detailed information of the structure of the ignition flame front. Simulated gas species concentrations at the bed surface, ignition flame front rate, and bed temperature......Straw is being used as main renewable energy source in grate boilers in Denmark. For optimizing operating conditions and design parameters, a one-dimensional unsteady heterogeneous mathematical model has been developed and experiments have been carried out for straw combustion in a fixed bed...... are in good agreement with measurements at different operating conditions such as primary air-flow rate, pre-heating of the primary air, oxygen concentration, moisture content in straw, and bulk density of the straw in the fixed bed. A parametric study indicates that the effective heat conductivity, straw...

  9. Characterization of ash melting behaviour at high temperatures under conditions simulating combustible solid waste gasification.

    Science.gov (United States)

    Niu, Miaomiao; Dong, Qing; Huang, Yaji; Jin, Baosheng; Wang, Hongyan; Gu, Haiming

    2018-05-01

    To achieve high-temperature gasification-melting of combustible solid waste, ash melting behaviour under conditions simulating high-temperature gasification were studied. Raw ash (RA) and gasified ash (GA) were prepared respectively by waste ashing and fluidized bed gasification. Results of microstructure and composition of the two-ash indicated that GA showed a more porous structure and higher content of alkali and alkali earth metals among metallic elements. Higher temperature promoted GA melting and could reach a complete flowing state at about 1250°C. The order of melting rate of GA under different atmospheres was reducing condition > inert condition > oxidizing condition, which might be related to different existing forms of iron during melting and different flux content with atmosphere. Compared to RA, GA showed lower melting activity at the same condition due to the existence of an unconverted carbon and hollow structure. The melting temperature for sufficient melting and separation of GA should be at least 1250°C in this work.

  10. Combustion of Jordanian oil shale using circulating fluidized bed

    International Nuclear Information System (INIS)

    Hamdan, M.; Al-Azzam, S.

    1998-11-01

    this study re[resents design and manufacturing of a lab-scale circulating fluidized bed (C.F.B) to burn low grade fuel such as Jordanian oil shale. Hydrodynamic properties of C.F.B. were studied like minimum fluidization velocity, circulation flux and carryover rate. a hot run was firstly conducted by the combustion of L.P.G. to start up the combustion process. It proceeds until reaching the minimum burning temperature of oil shale particles, at which time the LPG supply was gradually reduced and oil shale feeding started. soon after reaching a self sustainable condition of oil shale particles, the LPG supply was cut off. The main combustion variables were investigated such as air to fuel ratios, temperature profiles across the bed, exhaust gas analysis and combustion efficiency. a combustion intensity of 859 kg/hr.m 2 and combustion efficiency of 96% were achieved. (authors). 19 refs., 9 tab., 18 fig

  11. ERA-Net Evaluation of technology status for small-scale combustion of pellets from new ash rich biomasses - combustion tests in residential burners

    Energy Technology Data Exchange (ETDEWEB)

    Roennbaeck, Marie; Johansson, Mathias; Frida Claesson

    2008-07-01

    In this project, pellets with higher ash content compared to the wood pellets used today on the Swedish market were tested in three domestic-scale burners. The tests were carried out based on EN 303-5. In the flue gas, combustion parameters as carbon monoxide, carbon dioxide, oxygen and hydro carbons were measured, and also more fuel specific parameters such as nitrogen oxides, sulphur dioxide, hydrogen chloride, total dust and particle mass- and number concentration. The dust (fly ash) and bottom ash were characterized chemically. The implications of high ash content on combustion performance are discussed in the report. Altogether five pellets with 8 mm diameter were tested: oilseed straw pellet, reed canary grass pellet (RCG), barley straw pellet, bark pellet and wood pellet. All fuels were dry ranging from 6.5-12 % moisture. The ash content varied from 0.3 weight-% dm in wood to 7.9 % in RCG. Barley straw has a noticeable low ash melting temperature, < 980 deg C, and could not be combusted in any of the burners. The nitrogen content varied nine times and sulphur more than 10 times. The chlorine content was very low in wood and bark and more than 20 times higher in oilseed and barley. The composition of inorganic species in the fuel ash was dominated by calcium, potassium and silica in wood, bark and oilseed pellet, while RCG and barley straw were dominated by silica. The three burners used were commercial and known to fulfil high quality requirements. Burner A is a pellet burner where fuel is supplied on top of the grate with no mechanical mean for moving bottom ash on the grate during combustion. Bottom ash is blown away, and any slag remaining on the grate is removed with a scrape before ignition. Burner B is an upward burning pellet burner where fuel and ash is pushed upwards and the glow bed is exposed to the surrounding combustion department. Burner C is a forward burning grain burner that pushes fuel and ash forwards, inside a cylinder. From the

  12. DOLOMITE DESULFURIZATION BEHAVIOR IN A BUBBLING FLUIDIZED BED PILOT PLANT FOR HIGH ASH COAL

    Directory of Open Access Journals (Sweden)

    G. M. F. Gomes

    Full Text Available Abstract Although fluidized bed in situ desulphurization from coal combustion has been widely studied, there are aspects that remain under investigation. Additionally, few publications address Brazilian coal desulphurization via fluidized beds. This study used a 250 kWth bubbling fluidized bed pilot plant to analyze different aspects of the dolomite desulphurization of two Brazilian coals. Superficial velocities of 0.38 and 0.46 m/s, flue gas recycling, Ca/S molar ratios and elutriation were assessed. Results confirmed the influence of the Ca/S molar ratio and superficial velocity - SO2 conversion up to 60.5% was achieved for one coal type, and 70.9% was achieved for the other type. A recycling ratio of 54.6% could increase SO2 conversion up to 86.1%. Elutriation and collection of ashes and Ca-containing products did not present the same behavior because a lower wt. % of CaO was collected by the gas controlled mechanism compared to the ash.

  13. Fly ashes from coal and petroleum coke combustion: current and innovative potential applications.

    Science.gov (United States)

    González, Aixa; Navia, Rodrigo; Moreno, Natalia

    2009-12-01

    Coal fly ashes (CFA) are generated in large amounts worldwide. Current combustion technologies allow the burning of fuels with high sulfur content such as petroleum coke, generating non-CFA, such as petroleum coke fly ash (PCFA), mainly from fluidized bed combustion processes. The disposal of CFA and PCFA fly ashes can have severe impacts in the environment such as a potential groundwater contamination by the leaching of heavy metals and/or particulate matter emissions; making it necessary to treat or reuse them. At present CFA are utilized in several applications fields such as cement and concrete production, agriculture and soil stabilization. However, their reuse is restricted by the quality parameters of the end-product or requirements defined by the production process. Therefore, secondary material markets can use a limited amount of CFA, which implies the necessity of new markets for the unused CFA. Some potential future utilization options reviewed herein are zeolite synthesis and valuable metals extraction. In comparison to CFA, PCFA are characterized by a high Ca content, suggesting a possible use as neutralizers of acid wastewaters from mining operations, opening a new potential application area for PCFA that could solve contamination problems in emergent and mining countries such as Chile. However, this potential application may be limited by PCFA heavy metals leaching, mainly V and Ni, which are present in PCFA in high concentrations.

  14. Considerations on valorization of biomass origin materials in co-combustion with coal in fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    I. Gulyurtlu; P. Abelha; H. Lopes; A. Crujeira; I. Cabrita [DEECA-INETI, Lisbon (Portugal)

    2007-07-01

    Co-combustion of biomass materials with coal is currently gaining increasing importance, in order to meet the targets on greenhouse gas emissions, defined in the Kyoto protocol. Co-firing of coal with biomass materials could be the short-term solution in reducing CO{sub 2} emissions from power stations. The work undertaken studied co-firing of meat and bone meal (MBM), olive cake and straw pellets with bituminous coals from Colombia (CC) and Poland (PC), which are commonly used in European power stations. The co-combustion studies were carried out on the pilot fluidized bed installation of INETI. Gaseous pollutants and solid concentration in flue gases and ashes from different locations were monitored. Results obtained indicate that the co-feeding of biomass materials did not present any problem and ensured stable combustion conditions and high efficiency. However, for temperatures above 800{sup o}C, bed agglomeration could be observed for all biomass species studied. Most of the combustion of biomass material, contrary to that of coal, was observed to take place in the riser where the temperature was as high as 150-250{sup o}C above that of the bed. SO{sub 2} and NOx levels were found to be lower. The emissions of dioxins could be considerable with fuels with high Cl as is the case with straw. However, mixing of fuels with high S content could lead to a strong reduction in dioxin emissions. Ashes produced from biomass combustion may be considered for further reutilization or landfilling. Other options depend on their characteristics, chemical composition and leaching behaviour. This was evaluated in this study.

  15. Diesel oil combustion in fluidized bed; Combustion de aceite diesel en lecho fluidizado

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Cazares, Mario [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1992-07-01

    The effect of the fluidized bed depth in the combustion in burning diesel oil in a fluidized bed, was analyzed. A self sustained combustion was achieved injecting the oil with an injector that utilized a principle similar to an automobile carburetor venturi. Three different depths were studied and it was found that the deeper the bed, the greater the combustion efficiency. Combustion efficiencies were attained from 82% for a 100mm bed depth, up to 96% for a 200mm bed depth. The diminution in the efficiency was mainly attributed to unburned hydrocarbons and to the carbon carried over, which was observed in the black smoke at the stack outlet. Other phenomena registered were the temperature gradient between the lower part of the bed and the upper part, caused by the fluidization velocity; additionally it was observed that the air employed for the oil injection (carbureting air) is the most important parameter to attain a complete combustion. [Espanol] Se analizo el efecto de la profundidad del lecho en la combustion al quemar aceite diesel en un lecho fluidizado experimental. Se logro combustion autosostenida inyectando el aceite con un inyector que utilizo un principio similar al venturi del carburador de automovil. Se estudiaron tres diferentes profundidades del lecho y se encontro que a mayor profundidad del lecho, mayor eficiencia de la combustion. Se lograron eficiencias de la combustion desde 82% para el lecho de 100 mm de profundidad hasta 96% para el de 200 mm. La disminucion de la eficiencia se atribuyo, principalmente, a los hidrocarburos no quemados y al carbon arrastrado, lo cual se observo en el humo negro a la salida de la chimenea. Otros fenomenos registrados fueron el gradiente de temperatura entre la parte baja del lecho y la parte superior causado por la velocidad de fluidizacion; ademas, se observo que el aire utilizado para inyectar el aceite (aire de carburacion) es el parametro mas importante para lograr una combustion completa.

  16. Successful experience with limestone and other sorbents for combustion of biomass in fluid bed power boilers

    Energy Technology Data Exchange (ETDEWEB)

    Coe, D.R. [LG& E Power Systems, Inc., Irvine, CA (United States)

    1993-12-31

    This paper presents the theoretical and practical advantages of utilizing limestone and other sorbents during the combustion of various biomass fuels for the reduction of corrosion and erosion of boiler fireside tubing and refractory. Successful experiences using a small amount of limestone, dolomite, kaolin, or custom blends of aluminum and magnesium compounds in fluid bed boilers fired with biomass fuels will be discussed. Electric power boiler firing experience includes bubbling bed boilers as well as circulating fluid bed boilers in commercial service on biomass fuels. Forest sources of biomass fuels fired include wood chips, brush chips, sawmill waste wood, bark, and hog fuel. Agricultural sources of biomass fuels fired include grape vine prunings, bean straw, almond tree chips, walnut tree chips, and a variety of other agricultural waste fuels. Additionally, some urban sources of wood fuels have been commercially burned with the addition of limestone. Data presented includes qualitative and quantitative analyses of fuel, sorbent, and ash.

  17. Ash quality and environmental quality assurance system in co-combustion - Co-combustion of forest industry waste

    International Nuclear Information System (INIS)

    Laine-Ylijoki, J.; Wahlstroem, M.

    2000-01-01

    The environmental acceptability and possible utilization of co-combustion ashes will have a significant influence on the wider use of co-combustion in the future. At present the correlation between currently used fuels, their mixture ratios, and quality variations in ashes are not known, which complicates the assessment of possible utilization and environmental acceptability of co-combustion ashes. The composition of ashes has also been found to vary significantly. Effective utilization requires that process variations to alter ash composition and quality variations are known in advance. The aim of the research was to characterize the fly ash from co- combustion of peat, wood and biological paper mill sludge produced under different fuel loadings, especially with and without sludge addition, ant to identify critical parameters influencing on the ash composition. The variations in the leaching properties of ashes collected daily were followed up. The environmental acceptability of the ashes produced under different fuel loadings, especially their suitability for use in road constructions, were evaluated. The project included also the preparation of laboratory reference material from ash material. Guidelines were developed for sampling, sample preparation and analysis, and leaching tests. Furthermore, a quality control system, including sampling strategies, sample analysis and leaching testing, was established

  18. Washing of fly ash from combustion of municipal solid waste using water as leachant; Vattentvaett av flygaska fraan avfallsfoerbraenning

    Energy Technology Data Exchange (ETDEWEB)

    Steenari, Britt-Marie; Zhao, Dongmei

    2010-03-15

    Ashes from combustion of municipal solid waste contain a large amount of minerals, salts and other metal compounds that are more or less soluble in water. The metal salts are often enriched in the fly ash which leads to a classification of the ash as hazardous waste. This makes ash management complicated and costly. Many stabilisation methods for Municipal Solid Waste Incineration (MSWI) fly ash have been developed and most of them are based on a removal of chloride and sulfate in addition to a binding of metals in less soluble forms. The aim is to avoid the common situation that the ash does not comply to leaching limit values due to release of harmless salts. The aim of this project was to investigate if a simple washing with water can remove enough of the fly ash content of chloride and sulphate so that the ash can be landfilled in a simpler and less costly way than today. The project was focused on fly ashes from the MSWI units owned by Boraas Energi och Miljoe AB and Renova AB Goeteborg, i.e. a electro filter ash from grate fired boilers at Renova and a cyclone ash from a fluid bed boiler at Boraas. The results show that the main part of the chloride content of the ashes can be removed easily, but the washing with water is less effective in the removal of sulphate. A water-to-ash ratio of 1-2 l/kg removes about 100% of chloride but only 8-16% of the sulphate content. In many cases, the leachability of sulphate increases after the washing step. This is due to the rather complex sulphate chemistry with several possible reactions taking place in the ash-water system. For both the tested ashes the high level of chloride leaching is an important factor that prevents admittance on a landfill for hazardous waste without treatment.. The leaching of certain metals, such as Pb, is also high from both ashes but in the case of the Renova fly ash this is dealt with by treatment of the ash according to the Bamberg method. After a water washing with L/S 1-2 (L/kg dry ash

  19. N2O emission under fluidized bed combustion condition

    International Nuclear Information System (INIS)

    Shen, B.X.; Yao, Q.; Mi, T.; Liu, D.C.; Feng, B.; Winter, Franz

    2003-01-01

    In this paper, many rules about N 2 O and NO x emission under fluidized bed combustion conditions were found by experiments. The research results indicate that CaO, CaSO 4 , Fe 2 O 3 and char have important influence on decomposition of N 2 O; co-combustion of coal and biomass are effective measures to low N 2 O and NO x emission

  20. Mathematical model for solid fuel combustion in fluidized bed

    International Nuclear Information System (INIS)

    Kostikj, Zvonimir; Noshpal, Aleksandar

    1994-01-01

    A mathematical model for computation of the combustion process of solid fuel in fluidized bed is presented in this work. Only the combustor part of the plant (the fluidized bed and the free board) is treated with this model. In that manner, all principal, physical presumption and improvements (upon which this model is based) are given. Finally, the results of the numerical realisation of the mathematical model for combustion of minced straw as well as the results of the experimental investigation of a concrete physical model are presented. (author)

  1. Atmospheric fluidized bed coal combustion research, development and application

    CERN Document Server

    Valk, M

    1994-01-01

    The use of fluidized bed coal combustion technology has been developed in the past decade in The Netherlands with a view to expanding the industrial use of coal as an energy supply. Various research groups from universities, institutes for applied science and from boiler industries participated and contributed to this research area. Comprehensive results of such recent experimentation and development work on atmospheric fluidized bed combustion of coal are covered in this volume. Each chapter, written by an expert, treats one specific subject and gives both the theoretical background as well a

  2. Oxy-fuel combustion on circulating fluidized bed. Chapter 5

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, E.J. [Canmet, Natural Resources Canada (Canada); Hack, H. [Foster Wheeler North America Corporation (United States)

    2011-07-01

    This paper explores the developments and field tests carried out with oxy-fuel fluidized bed combustion. This method has the advantage over the other options of emitting a pure stream of CO2 which thus does not need to be concentrated to be liquefied, transported and stored. In addition, pilot scale tests have shown that oxy-fired circulating fluidized bed combustion (CFBC) results in low emission and fuel flexibility. This paper highlighted that oxy-fired CFBC might be a good option for CCS but tests performed so far have been on a small scale. To confirm the promising results of pilot tests, demonstration projects are underway and are presented herein.

  3. Study of toxic metals during combustion of RDF in a fluidized bed pilot

    Energy Technology Data Exchange (ETDEWEB)

    Crujeira, T.; Lopes, H.; Abelha, P.; Sargaco, C.; Goncalves, R.; Freire, M.; Cabrita, I.; Gulyurtlu, I. [DEECA, INETI, Lisbon (Portugal)

    2005-04-01

    The study of the behavior of heavy metals during combustion of refuse-derived fuel (RDF) in a pilot fluidized bed was performed. The results of co-combustion were compared with coal combustion and RDF monocombustion. The amounts of heavy metals retained by the ash were different during co-firing in comparison with monocombustion due to the mechanisms leading to different partitioning of ash. It was verified that heavy metal emissions increased with introduction of RDF, but remained below regulated levels, with the exception of chromium (Cr) and nickel (Ni). For RDF monocombustion the emissions were, however, more severe, especially for cadmium (Cd), lead (Pb), and copper (Cu). This seems to be related not only to larger input amounts, but also to higher volatilisation during monocombustion caused by the presence of higher chlorine and lower sulphur contents in the RDF. Hence, as far as heavy metals are concerned, the utilization of RDF as a co-firing combustible for coal seems to be more environmental favorable than when RDF is fired alone.

  4. Mercury removal from coal combustion flue gas by fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Junyan [Chinese Academy of Sciences, Beijing (China). Research Center for Process Pollution Control; Chinese Academy of Sciences, Beijing (China). Graduate Univ.; Xu, Wenqing; Zhu, Tingyu; Jing, Pengfei [Chinese Academy of Sciences, Beijing (China). Research Center for Process Pollution Control

    2013-07-01

    The effect of physicochemical properties on the mercury adsorption performance of three fly ash samples has been investigated. The samples were tested for mercury adsorption using a fixed-bed with a simulated gas. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy and other methods were used to characterize the samples. The results indicate that mercury adsorption on fly ash is mainly physisorption and chemisorption. Uncompleted burned carbon is an important factor for the improvement of mercury removal efficiency, especially, the C-M bond may improve the oxidation of mercury, which formed via the reaction of C and Ti, Si and other elements. The higher specific surface areas and smaller pore diameter are all beneficial for the high mercury removal efficiency. The presence of O{sub 2} plays a positive role on Hg adsorption of modified fly ash, while SO{sub 2} has double role of inhibition because of competitive adsorption and promotion to chemisorption. In addition, sample modified with FeCl{sub 3} has a great performance in Hg removal.

  5. Chemical Processes Related to Combustion in Fluidised Bed

    Energy Technology Data Exchange (ETDEWEB)

    Steenari, Britt-Marie; Lindqvist, Oliver [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Environmental Inorganic Chemistry

    2002-12-01

    This report covers work that has been carried out in the combustion chemistry group at the Dept. of Environmental Inorganic Chemistry, Chalmers, within the STEM project 12859-1, during the period 2000-07-01 to 2002-06-30. The work was comprised of the following parts: Sulphur chemistry under pressurised and atmospheric conditions; Gas/solid reactions related to sintering and fouling; Chemistry of volatile metals in combustion; Ash leaching properties; Theoretical modelling of the interactions between ions in a solution and mineral surfaces; Some related issues and co-operations with other departments. The work on sulphur chemistry has been a central issue in our group and it has now been finalised with a PhD thesis discussing some aspects of the sulphation of limestone under pressurised conditions. The influence of a number of parameters on the sulphation efficiency was investigated and compared with similar studies under atmospheric conditions. In a special study it was shown that the influence of alternating calcining - non-calcining conditions on the conversion was substantial. In addition, the oxidation of CaS and sulphided limestone was studied and a regeneration method for the sulphide sorbent was proposed. In the project part concerning gas - solid reactions that are relevant to sintering and fouling, the application of an on-line measurement technique for the study of alkali metal capture by kaolin or other sorbents is described. A new reactor set-up has been constructed and the initial results from this set up are promising. The chemistry of cadmium in combustion of MSW and biomass is the object of a PhD project. This work has been concentrated on the task of identifying Cd-compounds in fly ash samples. It has now come to a point where enough data has been collected to make it possible to give an indication about the Cd speciation in some ash types. In MSW ash particles, cadmium seem to occur mainly as chloride, oxide and sulphate. The work will continue

  6. Some aspects of the technology improvement for heat reprocessing of the combustible radioactive wastes and ash residue conditioning

    International Nuclear Information System (INIS)

    Dmitriev, S.A.; Lifanov, F.A.; Knyazev, I.A.; Buravchenko, N.N.; Sobolev, I.A.; Mamaev, L.A.; Alekseev, A.N.; Simagina, O.S.

    1991-01-01

    The results of studies devoted to increasing the efficiency of thermal reprocessing (combustion) of organic low- and intermediate-level radioactive wastes are given. The new most efficient three-stage process including: 1) gasification and pyrolysis of an organic material with volatile product release, 2) coke residual combustion, ash and noncombustible materials melting, 3) combustion of volatile products of thermal decomposition is developed on the basis of the analysis of solid radioactive waste combustion schemes, mathematical simulation and laboratory studies. Experimental bed, in which these processes are realized, is created. The results obtained in it have allowed one to begin designing of the pilot-commercial plant with shaft furnace having the capacity up to 200 kg/h for solid wastes

  7. Modelling of Devolatilization in Fluidized Bed Combustion

    DEFF Research Database (Denmark)

    Stenseng, Mette; Lin, Weigang; Johnsson, Jan Erik

    1997-01-01

    A mathematical model is developed to describe the devolatilization process in a circulating fluidized bed combustor. The model is a combination of two submodels: single particle devolatilization and fluid dynamics. The single particle model includes the influence of both chemical kinetics and hea...

  8. Packed Bed Reactor Technology for Chemical-Looping Combustion

    NARCIS (Netherlands)

    Noorman, S.; Sint Annaland, van M.; Kuipers, J.A.M.

    2007-01-01

    Chemical-looping combustion (CLC) has emerged as an alternative for conventional power production processes to intrinsically integrate power production and CO2 capture. In this work a new reactor concept for CLC is proposed, based on dynamically operated packed bed reactors. With analytical

  9. International evaluation of the programme on fluid bed combustion and gasification

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, H [Ruhr Univ., Bochum (Germany); Magnusson, B F [Norwegian Univ. of Science and Technology, Trondheim (Norway); Reed, T [Colorado School of Mines (United States)

    1997-12-31

    This report on the Swedish National Program on Fluid Bed Combustion and Gasification is part of the on-going evaluation process adopted by the funding organization NUTEK. This agency has invited the undersigned to act as members of an international panel responsible for evaluating the progress made in 9 projects initiated between 1993-1996. The output of this evaluation procedure is given in this report. The main aim of the Fluid Bed Combustion and Gasification Program is to develop industrially relevant knowledge and competence in experimental and computational techniques capable of characterizing the flow, heat transfer, combustion, gasification, ash formation and deposition and emissions in fluid bed gasifiers and combustors. To achieve this aim NUTEK is sponsoring research in a number of universities and encourages close cooperation between universities and industry. In the evaluation of the various sponsored research programs, the evaluation committee has considered the following key points: relevance of research to industrial needs; originality of research; program management; adequacy of resources; degree of collaboration between industry and academia; international standing of research. In this report comments and recommendations are made on individual projects as well as on the programme in general and they express the unanimous view of the panel members

  10. International evaluation of the programme on fluid bed combustion and gasification

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, H. [Ruhr Univ., Bochum (Germany); Magnusson, B.F. [Norwegian Univ. of Science and Technology, Trondheim (Norway); Reed, T. [Colorado School of Mines (United States)

    1996-12-31

    This report on the Swedish National Program on Fluid Bed Combustion and Gasification is part of the on-going evaluation process adopted by the funding organization NUTEK. This agency has invited the undersigned to act as members of an international panel responsible for evaluating the progress made in 9 projects initiated between 1993-1996. The output of this evaluation procedure is given in this report. The main aim of the Fluid Bed Combustion and Gasification Program is to develop industrially relevant knowledge and competence in experimental and computational techniques capable of characterizing the flow, heat transfer, combustion, gasification, ash formation and deposition and emissions in fluid bed gasifiers and combustors. To achieve this aim NUTEK is sponsoring research in a number of universities and encourages close cooperation between universities and industry. In the evaluation of the various sponsored research programs, the evaluation committee has considered the following key points: relevance of research to industrial needs; originality of research; program management; adequacy of resources; degree of collaboration between industry and academia; international standing of research. In this report comments and recommendations are made on individual projects as well as on the programme in general and they express the unanimous view of the panel members

  11. Combustion of palm oil solid waste in fluidized bed combustor

    International Nuclear Information System (INIS)

    Abdullah, I.; Shamsuddin, A.H.; Sopian, K.

    2000-01-01

    Results of experimental investigations of fluidized bed combustion of palm oil wastes consisting of shell, fibre and empty fruit bunches high heating value of 17450 kJ/kg and low heating value of 14500 kJ/kg. The fluidized bed combuster used has a vessel size of 486 x 10 6 mm 3 , surface area of evaporation tubes and distribution air pipes of 500 mm 2 and 320 mm 2 respectively. It was found that a fuel feeding rate 160 kg/h is required to achieve a steam flow rate of 600 kg/h, with the combustion efficiency 96% and boiler efficiency of 72%, emission level of flue gas NO x at less than 180 ppm, SO 2 at less than 20 ppm are measured in the flue gas. (Author)

  12. Combustion of cork waste in a circulating fluidized bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, I.; Boavida, D.; Miranda, M.; Cabrita, I. [Dept. de Tecnologias de Combustao, ITE-INETI, Lisboa (Portugal); Abelha, P. [Coaltec e Ambiente, Lisboa (Portugal)

    1999-07-01

    There is currently an ongoing joint project between Portugal and Spain, which is being funded by the FAIR programme. The principal objective of the FAIR project is to investigate the application of the fluidised bed combustion (FBC) technology to burn cork wastes with the aim of overcoming the difficulties currently experienced in the cork processing industries. The combustion studies at INETI were carried out using the 300 kW{sub th} circulating fluidised bed facility. The combustor is square in cross section with each side being 0.3 m long. The combustor height is 5 m. The temperatures in the bed, the riser and that of the flue gases leaving the reactor were continuously monitored. The combustion gases leaving the reactor passed through the recycling cyclone first to capture most of particulates elutriated out of the combustor. The solid particles were intermittently collected for analysis to determine the amount of carbon present, which helped the combustion efficiency to be calculated. Instantaneous measurements of O{sub 2}, CO, CO{sub 2}, NO{sub x}, N{sub 2}O and SO{sub 2} present levels in the flue gases were also carried out. The combustion tests were done with both the cork waste dust and granular virgin cork. The difference is that cork dust gets contaminated during the process due to the use of various additives. Most of the combustion took place in the riser where the temperature was at times up to 523 K above that of the bed. The unburned carbon level was low ranging from about 1.5 to 2.% suggesting that most of the particles burned to completion in the riser. (orig.)

  13. Effect of bed particles to combustion of gases in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Raiko, R.; Wallen, V.; Etelaeaho, R.; Correia, S. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1997-10-01

    The objective of this project was to obtain experimental data on effects of sand particles to the combustion of gases. The effect of the surface area of the particles was tested using different sized particles. The fluidized bed reactor used in these experiments was a stainless-steel tube with an internal diameter of 42 mm surrounded by an electric heater. The test rig was built in the Laboratory of Energy and Process Engineering at Tampere University of Technology. In order to elucidate the possible changes of particle surface, microscopic and porosimetric studies were conducted with both fresh bed particles and used bed particles. These measurements indicate that carbon monoxide significantly reacts with oxygen in the particulate or emulsion phase of a fluidized bed, if the residence time is long enough. The reaction rate depends mainly on temperature, air coefficient, residence time and particle size of the solids. It seems that the combustion enhances if the average particle size increases. Whether this is caused by increased free path length or reduced specific surface area of the bed is yet unknown. The first might be more probable cause because the majority of reactions often took place in the freeboard right above the bed. It was clear that the bed hindered proper combustion in several cases. (orig.)

  14. The synergistic effect in coal/biomass blend briquettes combustion on elements behavior in bottom ash using ICP-OES

    Energy Technology Data Exchange (ETDEWEB)

    Lazaroiu, G.; Frentiu, T.; Maescu, L.; Mihaltan, A.; Ponta, M.; Frentiu, M.; Cordos, E. [Universitatea Politehnica din Bucuresti, Bucharest (Romania)

    2009-05-15

    This paper focuses on the study of the synergistic effect in coal/biomass blend briquettes combustion on behavior of Al, As, Ba, Cd, Co. Cr, Cu, Fe, Ga, K, Mn, Mo, Ni, P, Pb, Si, V, W, Zn, Zr and characterization of raw materials and bottom ashes. The manufacturing of coal/biomass briquettes although not commonly used is an attractive approach, as briquettes combustion is more technologically advantageous than the fluidized bed combustion. In the same time this technology is a way to render valuable materials of low calorific power and results in diminishing polluting emission. Raw materials and briquettes from different blends of pitcoal/sawdust were subjected to combustion in a 55 kW-boiler. The total content of elements after digestion in the HNO{sub 3} - HF mixture and the content in water leachate at a solid/liquid ratio of 1:2 were determined both in raw materials and bottom ash by ICP-OES. The total content of elements was higher in pitcoal than in sawdust. The synergistic effect depends both on coal/biomass ratio in blend and element nature. The water leachable fraction of elements from ash decreased along with the increase of sawdust weight excepting macronutrients (K, P) and Si.

  15. Thermal valorization of footwear leather wastes in bubbling fluidized bed combustion.

    Science.gov (United States)

    Bahillo, A; Armesto, L; Cabanillas, A; Otero, J

    2004-01-01

    Transformation of hide (animal skins) into leather is a complicated process during which significant amounts of wastes are generated. Footwear is the sector that consumes the major part of leather (60%). Logically, this industry is producing the largest quantity of leather wastes. The objective of this work was to demonstrate the technical feasibility of fluidized bed technology to recover the energy from burning footwear leather wastes. Considering the characteristics of leather waste, especially the heating value (12.5-21 MJ/kg), it can be considered a fairly good fuel. Moreover, leather waste has suitable characteristics for combustion, e.g., high volatile matter (76.5%) and low ash content (5.2%). Two factors deserve special attention: N3O and NOx emissions as a consequence of its unusual high nitrogen content (14.1%) and the chromium speciation because chromium is the main element of ash (3.2%) due to its use in leather tanning. A series of experiments has been carried out in a 0.1 MWt bubbling fluidized bed pilot plant. The combustion efficiency, flue gas composition and chromium speciation were investigated. Despite having high nitrogen content, a low conversion rate of fuel-N to NOx and N2O was attained. Chromium was concentrated in the solid streams and it was consistently found as Cr(III+); no presence of Cr(VI+) was detected.

  16. Nitrogen Chemistry in Fluidized Bed Combustion of Coal

    DEFF Research Database (Denmark)

    Jensen, Anker Degn

    and reduction by homogeneous and heterogeneous reactions. The data for the estimation of kinetics of the heterogeneous reactions were measured by one of the partners in the project for char and bed material sampled from a pressurized FBC pilot plant burning Kiveton Park coal. Experimental data from the pilot...... plant were used for model verification. The simulations of the NO emission during staged combustion and NH3 injection for NO reduction were in qualitative agreement with the experimental data. A parametric study of the influence of operating conditions on the conversion of fuel-N to NO showed......, the gas interchange coefficient, the bubble size and the bubble rise velocity. The most important combustion parameters were the rate of CO and CH4 combustion and the fraction of CO produced from char combustion. By using a rate of production analysis, the important reactions in the NO model were...

  17. The Influence of Particle Size, Fluidization Velocity, and Fuel Type on Ash-Induced Agglomeration in Biomass Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Gatternig, Bernhard, E-mail: bernhard.gatternig@cbi.uni-erlangen.de; Karl, Jürgen [Chair of Energy Process Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Nuremberg (Germany)

    2014-11-19

    Agglomeration of the bed material is one of the main obstacles for biomass utilization in fluidized bed combustors. Especially, high-potential fuels such as fast growing energy crops or biogeneous residues are affected because of their high content of alkaline metals. Despite ongoing research efforts, the knowledge base on what fuels are affected is still limited. This paper describes the design and installation of two lab-scale reactors for the experimental determination of agglomeration temperatures. The reactor concept and measurement method were developed under consideration of experiences from existing test rigs published in literature. Preliminary tests confirmed a reproducibility of ±5°C for both new reactors. The results of an extended measurement campaign (156 test runs of 25 fuel species at a wide range of the operational parameters “bed particle size,” “gas velocity,” and “bed ash accumulation”), based on “design of experiment” (DoE) criteria, showed high-agglomeration tendencies for residues (e.g., dried distillery grains, corn cobs) while woody energy crops (e.g., willow, alder) exhibited very stable combustion behavior. The operating parameters influenced the agglomeration behavior to a lesser degree than different ash compositions of fuel species tested. An interpolation within the DoE factor space allowed for a subsequent comparison of our results with experiments reported in literature. Good agreement was reached for fuels of comparable ash composition considering the interpolation errors of ±32°C on average.

  18. Emission studies from combustion of empty fruit bunch pellets in a fluidized bed combustor

    Science.gov (United States)

    Fazli Othaman, Muhamad; Sabudin, Sulastri; Faizal Mohideen Batcha, Mohd

    2017-08-01

    Malaysia is producing a very large amount of biomass annually from milling activities of oil palm. This biomass is currently being used efficiently in many ways including as fuel for boilers together with fossil fuels. This paper reports the emission characteristics from biomass combustion in a swirling fluidized bed combustor (SFBC). Pelletized empty fruit bunch (PEFB), one of largest biomass produced from oil palm industries were used as fuel in the present study. Combustion experiments were conducted with several quantitiesof excess air: 20%, 40%, 60% and 80% for a constant fuel feedrate of 30kg/hr. The effect of excess air was investigated for three major emissions gaseous namely CO, CO2 and NOx. Fly ash produced from the combustion was also analysed to find the contents of unburnt carbon and other impurities. From the results, it was found that the emission of CO decreased from 64 ppm to 40 ppm while the amount of CO2 increased slightly with the increasing of excess air from 20% to 80%. The NOx emission also increased from 290 ppm to 350 ppm because of N2 in the EA reacts with O2 due to high combustion temperature. The combustion efficiencies of about 99% obtained in the present study, showing the prospects of using SFBC in commercial scale.

  19. Electrodialytic removal of cadmium from biomass combustion fly ash in larger scale

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Ottosen, Lisbeth M.; Simonsen, Peter

    2005-01-01

    Due to a high concentration of the toxic heavy metal cadmium (Cd), biomass combustion fly ash often fails to meet the Danish legislative requirements for recycling on agricultural fields. It has previously been shown that it is possible to reduce the concentration of Cd in different bio ashes...... significantly by using electrodialytic remediation, an electrochemically assisted extraction method. In this work the potential of the method was demonstrated in larger scale. Three different experimental set-ups were used, ranging from bench-scale (25 L ash suspension) to pilot scale (0.3 - 3 m3......). The experimental ash was a straw combustion fly ash suspended in water. Within 4 days of remediation, Cd concentrations below the limiting concentration of 5.0 mg Cd/kg DM for straw ash were reached. On the basis of these results, the energy costs for remediation of ash in industrial scale have been estimated...

  20. Pressurized fluidized-bed combustion technology exchange workshop

    Energy Technology Data Exchange (ETDEWEB)

    ,

    1980-04-01

    The pressurized fluidized-bed combustion technology exchange workshop was held June 5 and 6, 1979, at The Meadowlands Hilton Hotel, Secaucus, New Jersey. Eleven papers have been entered individually into EDB and ERA. The papers include reviews of the US DOE and EPRI programs in this area and papers by Swedish, West German, British and American organizations. The British papers concern the joint program of the USA, UK and FRG at Leatherhead. The key factor in several papers is the use of fluidized bed combustors, gas turbines, and steam turbines in combined-cycle power plants. One paper examines several combined-cycle alternatives. (LTN)

  1. CFD simulation of ash deposit formation in fixed bed biomass furnaces and boilers

    NARCIS (Netherlands)

    Forstner, M.; Hofmeister, G.; Joeller, M.; Dahl, J.; Braun, M.; Kleditzsch, S.; Scharler, R.; Obernberger, I.

    2006-01-01

    In order to describe and predict the formation of ash deposits in biomass fired combustion plants, a mathematical model is being developed and implemented into the CFD code Fluent¿ as a post processing tool. At the present state of development the model covers the release of coarse ash particles and

  2. Microwave-assisted synthesis of geopolymers from fluidised bed gasifier bottom ash

    CSIR Research Space (South Africa)

    Oboirien, BO

    2013-09-01

    Full Text Available Fluidised bed gasification (FBG) is a clean coal technology suitable for power and fuel generation from low grade coals. However, the resulting bottom ash presents some disposal challenges to the power plants and the environment. The production...

  3. Element budgets of forest biomass combustion and ash fertilisation - a Danish case-study

    DEFF Research Database (Denmark)

    Ingerslev, Morten; Skov, Simon; Sevel, Lisbeth

    2011-01-01

    Harvest of forest biomass for energy production may lead to a significant export of nutrients from the forest. Ash spreading and recycling of nutrients from wood chip combustion to the forest has come into focus as a means for counteracting the nutrient export. This study was carried out to examine...... the retention of various elements in the different ash fractions and utilise the nutrient recovery to evaluate the fertiliser quality of the examined ash. The mass and element flux of wood chips, bottom ash, cyclone fly ash and condensation sludge at Ebeltoft central heating plant was studied over a four day...

  4. Limestone attrition under simulated oxyfiring Fluidized-Bed combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Scala, F. [Istituto di Ricerche sulla Combustione - CNR, Napoli (Italy); Salatino, P. [Dipartimento di Ingegneria Chimica - Universita degli Studi di Napoli Federico II, Napoli (Italy)

    2009-03-15

    Limestone attrition by surface wear was studied during the flue gas desulfurization under simulated fluidized-bed (FB) oxyfiring conditions and hindered calcination. Bench-scale experimental tests were carried out using well-established techniques previously developed for the characterization of sulfation and attrition of sorbents in air-blown atmospheric FB combustors. The experimental limestone conversion and attrition results were compared with those previously obtained with the same limestone under simulated air-blown combustion conditions. The differences in the conversion and attrition extents and patterns associated with oxyfiring as compared to air-blown atmospheric combustion were highlighted and related to the different particle morphologies and thicknesses of the sulfate layer. It was noted that attrition could play an important role in practical circulating FB combustor operation, by effectively enhancing particle sulfation under both oxyfiring and air-blown combustion conditions. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  5. The research and development of pressurized ash agglomerating fluidized bed coal gasification

    Energy Technology Data Exchange (ETDEWEB)

    Fang Yitian; Wu Jinhu; Chen Hanshi [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

    1999-11-01

    Coal gasification tests in a pressurized ash agglomeration fluidized bed coal gasifier were carried out. The effects of pressure and temperature on the gasification capacity, carbon conversion, carbon content in discharged ash and gas composition were investigated. Gasification capacity was shown to be in direct proportion to operation pressure. Tests of hot gas dedusting using a moving granular bed were also carried out. 3 refs., 6 figs., 2 tabs.

  6. Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard

    Science.gov (United States)

    This page contains documents related to the evaluation of coal combustion residual beneficial use of fly ash concrete and FGD gypsum wallboard including the evaluation itself and the accompanying appendices

  7. Peach and apricot stone combustion in a bubbling fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Kaynak, B.; Atimtay, Aysel T. [Department of Environmental Engineering, Middle East Technical University, Ankara 06531 (Turkey); Topal, H. [Department of Mechanical Engineering, Engineering and Architecture Faculty, Gazi University, Ankara 06570 (Turkey)

    2005-07-25

    In this study, a bubbling fluidized bed combustor (BFBC) of 102 mm inside diameter and 900 mm height was used to investigate the combustion characteristics of peach and apricot stones produced as a waste from the fruit juice industry. A lignite coal was also burned in the same combustor. The combustion characteristics of the wastes were compared with that of a lignite coal that is most widely used in Turkey. On-line concentrations of O{sub 2}, CO, CO{sub 2}, SO{sub 2}, NO{sub X} and total hydrocarbons (C{sub m}H{sub n}) were measured in the flue gas during combustion experiments. By changing the operating parameters (excess air ratio, fluidization velocity, and fuel feed rate), the variation of emissions of various pollutants was studied. Temperature distribution along the bed was measured with thermocouples. During the combustion tests, it was observed that the volatile matter from peach and apricot stones quickly volatilizes and mostly burn in the freeboard. The temperature profiles along the bed and the freeboard also confirmed this phenomenon. It was found that as the volatile matter of fruit stones increases, the combustion takes place more in the freeboard region. The results of this study have shown that the combustion efficiencies ranged between 98.8% and 99.1% for coal, 96.0% and 97.5% for peach stone and 93.4% and 96.3% for apricot stones. The coal has zero CO emission, but biomass fuels have very high CO emission which indicates that a secondary air addition is required for the system. SO{sub 2} emission of the coal is around 2400-2800 mg/Nm{sup 3}, whereas the biomass fuels have zero SO{sub 2} emission. NO{sub x} emissions are all below the limits set by the Turkish Air Quality Control Regulation of 1986 (TAQCR) for all tests. As the results of combustion of two biomass fuels are compared with each other, peach stones gave lower CO and NO{sub x} emissions but the SO{sub 2} emissions are a little higher than for apricot stones. These results suggest that

  8. Electrochemical treatment of wood combustion fly ash for the removal of cadmium

    DEFF Research Database (Denmark)

    Damø, Anne Juul

    2002-01-01

    Due to a high content of macronutrients and a potential liming capacity, recycling of ashes from biomass combustion to agricultural fields as fertilisers and/or for soil improvement is considered in Denmark and other countries utilising biomass as an energy source. However, especially the fly ash...

  9. Variability of total and mobile element contents in ash derived from biomass combustion

    Czech Academy of Sciences Publication Activity Database

    Száková, J.; Ochecová, P.; Hanzlíček, Tomáš; Perná, Ivana; Tlustoš, P.

    2013-01-01

    Roč. 67, č. 11 (2013), s. 1376-1385 ISSN 0366-6352 R&D Projects: GA MZe QI102A207 Institutional support: RVO:67985891 Keywords : biomass combustion * fly ash * bottom ash * element contents Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.193, year: 2013

  10. Experiences in sulphur capture in a 30 MWth Circulating Fluidized Bed boiler under oxy-combustion conditions

    International Nuclear Information System (INIS)

    Gómez, M.; Fernández, A.; Llavona, I.; Kuivalainen, R.

    2014-01-01

    CO 2 and SO 2 from fossil fuel combustion are contributors to greenhouse effect and acid rain respectively. Oxy-combustion technology produces a highly concentrated CO 2 stream almost ready for capture. Circulating Fluidized Bed (CFB) boiler technology allows in-situ injection of calcium-based sorbents for efficient SO 2 capture. CIUDEN's 30 MWth CFB boiler, supplied by Foster Wheeler and located at the Technology Development Centre for CO 2 Capture and Transport (es.CO 2 ) in Spain, is the first of its kind for executing test runs at large pilot scale under both air-combustion and oxy-combustion conditions. In this work, SO 2 emissions under different scenarios have been evaluated. Variables such as limestone composition, Ca/S molar ratio and bed temperature among others have been considered along different test runs in both air-combustion and oxy-combustion conditions to analyse its influence on SO 2 abatement. Fly and bottom ash, together with flue gas analysis have been carried-out. Desulphurization performance tests results are presented. - Highlights: •Sulphur capture efficiency (%) was higher in oxy-combustion compared to air-combustion in a 30 MW thermal CFB boiler using anthracite and limestone as sulphur sorbent. •For a Ca/S molar ratio higher than 2.6 there was barely any improvement on sulphur capture efficiency for both air-combustion and oxy-combustion conditions in a 30 MW thermal CFB boiler using anthracite and limestone as sulphur sorbent. •Optimum temperature for sulphur capture at a fixed Ca/S molar ratio is around 880–890 °C under oxy-combustion conditions and for anthracite coal with limestone as sorbent in a 30 MW thermal CFB boiler

  11. Prevention of Bed Agglomeration Problems in a Fluidized Bed Boiler by Finding the Trigging Value of Sewage Sludge Dosage Added to Combustion of Biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Kajsa; Gervind, Pernilla

    2009-07-01

    Agglomeration of bed sand is a common problem during combustion of biofuels with high ash content in fluidized bed boilers. Former studies have shown that co-combustion of biofuels with sewage sludge increases the agglomeration temperature. Sewage sludge has a low heating value and high ash content. It would therefore be better to use sludge as an additive to the combustion than as a co-combusted biofuel. In this study the trigging value of sludge addition to the combustion of some biofuel was investigated. The effect of adding sludge with different precipitation chemicals, iron sulphate and aluminium sulphate, was investigated. The biofuels used for the experiments were bark, refused derived fuel (RDF) and a mixture of wood and straw, 75/25 % on energy basis. All experiments were carried out in a laboratory scale fluidized bed reactor. Analyses of chemical composition of bed sand and SEM/EDX analyses were performed after the combustion. Eventually agglomeration tests were performed in order to find the agglomeration temperature of the samples. Some of the samples sintered during the combustion and were not tested for the agglomeration temperature. SEM/EDX showed that all samples of bed sand contained sand particles with more or less coatings. In some cases the coatings seemed to consist of one dense inner layer and one more porous outer layer. From SEM/EDX and chemical composition analyses it was found that the total amount of phosphorous in the bed sand samples was increased with an increased addition of sludge in all experiments. The concentration of phosphorous was especially higher in the outer layers/coatings. It was also found that elements from the sludge seem to get caught by a sticky layer at the bed sand surface and form a non-sticky or less sticky layer that prevents agglomeration. The total amount of aluminium was increased with an increased addition of sludge for the wood/straw samples, while it increased with an increased amount of combusted fuel for

  12. Waste Water Treatment-Bed of Coal Fly Ash for Dyes and Pigments Industry

    Directory of Open Access Journals (Sweden)

    Syed Farman Ali Shah

    2015-12-01

    Full Text Available The highly porous power plant waste ashes have been utilized to treat toxic effluent of a dyes manufacturing plant. An attempt has been made for the first time in Pakistan, to generate an effective and economically sound treatment facility for the toxic effluent of a dyes manufacturing plant. This is an indigenous bed which could replace expensive treatment facilities, such as reverse osmosis (RO, granulated activated carbon (GAC bed, etc. The treatment efficiency was improved by coupling coagulants with fly ash adsorbent bed. The ash was collected from coal fired boilers of power plant at Lakhra Power Generation Company, Jamshoro, Pakistan. The use of this ash resolved the disposal and environmental issues by treating wastewater of chemical, dyes and pigment industry. The treatment bed comprised of briquettes of coal fly ash coupled with commercial coagulant ferrous sulfate-lime reduced COD, color, turbidity and TSS of effluent remarkably. An adsorption capacity and chemical behavior of fly ash bed was also studied. In coagulation treatment, coagulant FeSO4-lime influenced reduction of COD, color, turbidity and TSS by 32%, 48%, 50% and 51%, respectively. The CFAB coupled with coagulant, resulted an excessive removal of color, TSS, COD, and turbidity by 88%, 92%, 67% and89%, respectively.

  13. Waste Water Treatment-Bed of Coal Fly Ash for Dyes and Pigments Industry

    International Nuclear Information System (INIS)

    Shah, S.F.A.; Aftab, A.; Soomro, N.; Nawaz, M.S.; Vafai, K.

    2015-01-01

    The highly porous power plant waste ashes have been utilized to treat toxic effluent of a dyes manufacturing plant. An attempt has been made for the first time in Pakistan, to generate an effective and economically sound treatment facility for the toxic effluent of a dyes manufacturing plant. This is an indigenous bed which could replace expensive treatment facilities, such as reverse osmosis (RO), granulated activated carbon (GAC) bed, etc. The treatment efficiency was improved by coupling coagulants with fly ash adsorbent bed. The ash was collected from coal fired boilers of power plant at Lakhra Power Generation Company, Jamshoro, Pakistan. The use of this ash resolved the disposal and environmental issues by treating wastewater of chemical, dyes and pigment industry. The treatment bed comprised of briquettes of coal fly ash coupled with commercial coagulant ferrous sulfate-lime reduced COD, color, turbidity and TSS of effluent remarkably. An adsorption capacity and chemical behavior of fly ash bed was also studied. In coagulation treatment, coagulant FeSO/sun 4/-lime influenced reduction of COD, color, turbidity and TSS by 32 percentage, 48 percentage, 50 percentage and 51 percentage, respectively. The CFAB coupled with coagulant, resulted an excessive removal of color, TSS, COD, and turbidity by 88 percentage, 92 percentage, 67 percentage and 89 percentage, respectively. (author)

  14. Effect of Heterogeneity in Coal Ash Chemical Composition on the Onset of Conditions Favorable for Agglomeration in Fluid Beds

    Directory of Open Access Journals (Sweden)

    Aditi B. Khadilkar

    2015-11-01

    Full Text Available Ash agglomeration issues that arise due to the sticking of slag-wetted, colliding particles have been creating operational difficulties and monetary losses for the fluidized bed combustion (FBC industry. Difficulties have been experienced in the detection of slag-liquid at the low operating temperatures in fluidized bed combustors (FBCs and predicting the agglomeration behavior of fuel. This study aims to study the effect of heterogeneity in ash composition on the detection of slag-liquid in FBCs. It quantifies the slag-liquid amounts at the particle-level, under oxidizing environments, by dividing the bulk fuel into density classes. FactSage™ thermodynamic simulations of each of the particle classes, along with experimental validation of the trends with thermo-mechanical analysis (TMA and high temperature X-ray diffraction (HT-XRD were performed. The results obtained can be used to estimate the stickiness of particles in the development of ash agglomeration models based on particle collisions. The study of these particle classes shows that particle classes with specific minerals can form low temperature eutectics and lead to onset of slag-liquid formation at temperatures below those predicted by bulk analysis alone. Comparison of the differences in slag-liquid formation tendencies under reducing and oxidizing environments is also presented.

  15. Soot, organics and ultrafine ash from air- and oxy-fired coal combustion

    Science.gov (United States)

    This paper is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practically relevant s...

  16. Experimental on fly ash recirculation with bottom feeding to improve the performance of a circulating fluidized bed boiler co-burning coal sludge

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Lunbo; Xu, Guiling; Liu, Daoyin; Chen, Xiaoping; Zhao, Changsui [Southeast Univ., Nanjing (China). School of Energy and Environment

    2013-07-01

    With the aim of reducing carbon content in fly ash, fly ash recirculation with bottom feeding (FARBF) technology was applied to a 75 t/h Circulating Fluidized Bed (CFB) boiler burning mixture of coal and coal sludge. And industrial experiments were carried out to investigate the influence of FARBF technology on the combustion performance and pollutant emission characteristics of the CFB boiler. Results show that as the recirculation rate of fly ash increases, the CFB dense bed temperature decreases while the furnace outlet temperature increases, and the temperature distribution in the furnace becomes uniform. Compared with the conditions without fly ash recirculation, the combustion efficiency increases from 92 to 95% when the recirculation rate increases to 8 t/h, and the desulfurization efficiency also increases significantly. As the recirculation rate increases, the emissions of NO and CO decrease, but the particulate emission increases. The present study indicates that FARBF technology can improve the combustion performance and desulfurization efficiency for the CFB boilers burning coal sludge, and this can bring large economical and environmental benefits in China.

  17. Data summary of municipal solid waste management alternatives. Volume 5, Appendix C, Fluidized-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    None

    1992-10-01

    This appendix provides information on fluidized-bed combustion (FBC) technology as it has been applied to municipal waste combustion (MWC). A review of the literature was conducted to determine: (1) to what extent FBC technology has been applied to MWC, in terms of number and size of units was well as technology configuration; (2) the operating history of facilities employing FBC technology; and (3) the cost of these facilities as compared to conventional MSW installations. Where available in the literature, data on operating and performance characteristics are presented. Tabular comparisons of facility operating/cost data and emissions data have been complied and are presented. The literature review shows that FBC technology shows considerable promise in terms of providing improvements over conventional technology in areas such as NOx and acid gas control, and ash leachability. In addition, the most likely configuration to be applied to the first large scale FBC dedicated to municipal solid waste (MSW) will employ circulating bed (CFB) technology. Projected capital costs for the Robbins, Illinois 1600 ton per day CFB-based waste-to-energy facility are competitive with conventional systems, in the range of $125,000 per ton per day of MSW receiving capacity.

  18. Ashes of biomass combustion. Report of a workshop at 15 May 1997

    International Nuclear Information System (INIS)

    Zeevalkink, J.A.

    1997-12-01

    In a previous study the results of a study on the options to recycle or re-use ashes from biomass combustion were presented. Those results were discussed in detail in the title workshop, attended by researchers, market representatives that have to find practical solutions, and representatives of the Dutch government. It is concluded that only ashes from clean biomass can be used as a fertilizer (e.g. recycling of the ashes to forest soils), preferably in the form of granulated materials to realize a slow uptake of nutrients. Bottom ash can be applied in road construction materials or in concretes. In the appendices of this report sheets of 4 contributions are presented: ' Re-use of ashes form biomass combustion'; The Vattenfall project. Closing of the cycle in Sweden'; 'The vision of a biomass producer'; and ' The market problems for the initiator of biomass projects'. 3 appendices

  19. Effects of ashes in solid fuels on fuel particle charging during combustion in an air stream

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, A.G.; Fialkov, B.S.; Mel' nichuk, A.Yu.; Khvan, L.A.

    1982-09-01

    Black coal from the Karaganda basin is mixed with sodium chloride and graphite. Coal characteristics are given in a table (density, ashes, content of silica, aluminium oxides, iron oxides, calcium oxides, potassium oxides and magnesium oxides). Effects of ash fluctuations on electric potential of fuel particles during combustion are analyzed. Analyses show that with increasing ash content electric potential of fuel particles decreases and reaches the minimum when ash content ranges from 70 to 80 %. Particles with electric potential are generated during chemical processes between carbon and oxygen when coal is burned in an air stream. (5 refs.) (In Russian)

  20. A review of oxy-fuel combustion in fluidized bed reactors

    CSIR Research Space (South Africa)

    Mathekga, HI

    2016-06-01

    Full Text Available Presently, there is no detailed review that summarizes the current knowledge status on oxy-fuel combustion in fluidized bed combustors. This paper reviewed the existing literature in heat transfer, char combustion and pollutant emissions oxy...

  1. Bed agglomeration risk related to combustion of cultivated fuels (wheat straw, red canary grass, industrial hemp) in commercial bed materials; Baeddagglomereringsrisk vid foerbraenning av odlade braenslen (hampa, roerflen, halm) i kommersiella baeddmaterial

    Energy Technology Data Exchange (ETDEWEB)

    Erhardsson, Thomas; Oehman, Marcus; Geyter, Sigrid de; Oehrstroem, Anna

    2006-12-15

    The market of forest products is expanding and thus resulting in more expensive biomass fuels. Therefore research within the combustion industry for alternative fuels is needed, for example cultivated fuels. Combustion and gasification research on these cultivated fuels are limited. The objectives of this work was to increase the general knowledge of silicon rich cultivated fuels by study the agglomeration characteristics for wheat straw, reed canary grass and industrial hemp in combination with commercial bed materials. Controlled fluidized bed agglomeration tests was conducted in a 5 kW, bench-scale, bubbling fluidized bed reactor. The tendencies of agglomeration were determined with the three cultivated fuels in combination with various minerals present in natural sand (quarts, plagioclase and potassium feldspar) and an alternative bed material (olivine). During the experiments bed samples and formed agglomerates were collected for further analyses with a scanning electron microscope (SEM) and with X-ray microanalysis (EDS). Wheat straw had the highest agglomeration tendency of the studied fuels followed by reed canary grass and industrial hemp. No significant layer formation was found around the different bed particles. Instead, the ash forming matter were found as individual ash sticky (partial melted) particles in the bed. The bed material mineralogical composition had no influence of the agglomeration process because of the non layer formation propensities of the used silicon rich fuels.

  2. Formation of chlorinated organic compounds in fluidized bed combustion of recycled fuels

    International Nuclear Information System (INIS)

    Vesterinen, R.; Kallio, M.; Kirjalainen, T.; Kolsi, A.; Merta, M.

    1997-01-01

    Four tests of co-combustion of recycled fuels (REP) with peat and coal in the 15 kW fluidized bed reactor were performed. The recycled fuel was so-called dry fraction in four vessels sampling at Keltinmaeki. In three tests a part of peat energy was replaced with coal. The mixtures were prepared so that in all mixtures 25 % of energy was recycled fuel and 75 % was either peat or the mixture of peat and coal. The concentrations of polyaromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and chlorophenols decreased with increasing part of coal due to the increasing sulphur/chlorine ratio. Principal Component Analysis (PCA) and Partial Least Square regression analysis (PLS) showed that the chlorine, copper and sulphur contents of the fuel effected most on the concentrations of chlorophenols, chlorobenzenes, PCBs and PCDDs/PCDFs. Other variables influencing on a model were the lead concentration and the sulphur/chlorine ratio in fuel and the hydrogen chloride concentration of the flue gas. The concentrations of chlorophenols and chlorobenzenes were also significant for PCDD/PCDF concentrations in flue gas. The sulphur, chlorine, copper and chromium contents in fly ash and the temperature of the reactor influenced on the chlorophenol, chlorobenzene, PCB and PCDD/PCDF concentrations in fly ash. The chlorophenol and chlorobenzene contents in fly ash, the sulphur/chlorine ratio and the lead content in fuel, the sulphur dioxide, hydrogen chloride and carbon monoxide concentrations in flue gas had also influence on PCDD/PCDF concentrations in fly ash

  3. Combined distiller waste utilisation and combustion gases desulphurisation method. The case study of soda-ash industry

    Energy Technology Data Exchange (ETDEWEB)

    Kasikowski, Tomasz; Buczkowski, Roman; Cichosz, Marcin; Lemanowska, Eliza [Faculty of Chemistry, Nicolas Copernicus University, ul. Gagarina 7, 87-100 Torun (Poland)

    2007-09-15

    In this paper, a concept of technology that can be helpful for lowering the negative influence of the synthetic (based on the Solvay process) soda ash plant on the natural environment is presented. We describe the desulphurisation of combustion gases from the factory's power plant, which is based on their absorption in the overflow of distiller waste. The excess of lime milk, which is added in the process of ammonia regeneration from filter liquor, results in a strong alkalinity of distiller waste. The high pH of distiller waste favours absorption of acidic combustion gases. The laboratory-scale tests showed about 80% efficiency of the desulphurisation process. The suspension samples we obtained consist mainly of CaCO{sub 3}. We suggest using the obtained solid phase as an adsorbent-insert in Fluidised Bed Combustion technology (FBC). Based on raw material prices, production costs, and average sell prices of the product, economic analysis of innovation was executed. Profits from employing the method presented come mainly from reduction of environmental fees. The sensitivity analysis of cost showed that the application of the desulphurisation process causes cost reduction in soda-ash production accounting for EUR 150 thousand per year (excluding depreciation) in Poland, and EUR 11,700 thousand per year (excluding depreciation) in Sweden. It has been found that the latter value is similar to the positive environmental impact of this innovation expressed in monetary units (EUR 10,350 thousand per year, excluding depreciation). (author)

  4. Characteristic fly-ash particles from oil-shale combustion found in lake sediments

    International Nuclear Information System (INIS)

    Alliksaar, T.; Hoerstedt, P.; Renberg, I.

    1998-01-01

    Fly-ash particles accumulate in sediments and can be used to assess spatial distribution and temporal trends of atmospheric deposition of pollutants derived from high temperature combustion of fossil fuels. Previous work has concerned fly-ash derived from oil and coal. Oil-shale is the main fossil fuel used in Estonia and a major source of atmospheric pollution in the Baltic states. To assess if oil-shale power plants produce specific fly-ash particles scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) were used to compare fly-ash particles from oil-shale combustion with particles from oil and coal combustion. Two types were analysed, large black (10-30μm) and small glassy (< 5 μm) spheroidal particles. Although article morphology to some extent is indicative of the fuel burnt, morphological characters are not sufficient to differentiate between particles of different origin. However, the results indicate that with EDX analysis the fly-ash from oil-shale can be distinguished form oil and coal derived particles in environmental samples. Concentrations of large black and small glassy spheroidal fly-ash particles in a sediment core from an Estonian lake showed similar trends to oil-shale combustion statistics from Estonian power plants. 27 refs., 6 figs., 2 tabs

  5. Rheology of fly ashes from coal and biomass co-combustion

    DEFF Research Database (Denmark)

    Arvelakis, Stelios; Frandsen, Flemming

    2010-01-01

    The presence of large amounts of alkali metals, chlorine and sulphur in most biomass fuels - compared to coal - can create serious ash-related problems such as deposition, agglomeration and/or corrosion. This paper discusses the viscosity characteristics of fly ash from the co-combustion of various...... coal/biomass blends in a pilot scale pf-boiler. The produced data provide information on the melting of the ash and its flow characteristics, as a function of temperature, which may be used to modify the temperature profile of the boiler in order to avoid slagging. Straw co-firing lowers the ash...... viscosity leading to higher stickiness of the ash particles. Wood co-firing has only minor effects, due to the composition of wood ash and the low percentage of wood in the coal/biomass blend....

  6. Major gaseous and PAH emissions from a fluidized-bed combustor firing rice husk with high combustion efficiency

    International Nuclear Information System (INIS)

    Janvijitsakul, Kasama; Kuprianov, Vladimir I.

    2008-01-01

    This experimental work investigated major gaseous (CO and NO x ) and PAH emissions from a 400 kW th fluidized-bed combustor with a cone-shaped bed (referred to as 'conical FBC') firing rice husk with high, over 99%, combustion efficiency. Experimental tests were carried out at the fuel feed rate of 80 kg/h for different values of excess air (EA). As revealed by the experimental results, EA had substantial effects on the axial CO and NO x concentration profiles and corresponding emissions from the combustor. The concentration (mg/kg-ash) and specific emission (μg/kW h) of twelve polycyclic aromatic hydrocarbons (PAHs), acenaphthylene, fluorene, phenanthrene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene and indeno[1,2,3-cd]pyrene, were quantified in this work for different size fractions of ash emitted from the conical FBC firing rice husk at EA = 20.9%. The total PAHs emission was found to be predominant for the coarsest ash particles, due to the effects of a highly developed internal surface in a particle volume. The highest emission was shown by acenaphthylene, 4.1 μg/kW h, when the total yield of PAHs via fly ash was about 10 μg/kW h. (author)

  7. Ash behavior and de-fluidization in low temperature circulating fluidized bed biomass gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas

    ensures that high-alkali biomass fuels can be used without risks of bed de-fluidization. This thesis aims to understand the behavior of alkali metals and ash in the LTCFB system. The thesis work involved measurements made on bed material and product gas dust samples on a 100kW LTCFB gasifier placed......Biomass is increasingly used as a fuel for power generation. Herbaceous fuels however, contain high amounts of alkali metals which get volatilized at high temperatures and forms salts with low melting points and thus condense on pipelines, reactor surfaces and may cause de-fluidization. A Low......-Temperature Circulating Fluidized Bed System (LTCFB) gasifier allows pyrolysis and gasification of biomass to occur at low temperatures thereby improving the retention of alkali and other ash species within the system and minimizing the amount of ash species in the product gas. In addition, the low reactor temperature...

  8. Screening coal combustion fly ashes for application in geopolymers

    NARCIS (Netherlands)

    Valcke, S.L.A.; Pipilikaki, P.; Sarabér, A.J.; Fischer, H.R.; Nugteren, H.W.

    2013-01-01

    Driven by cost and sustainability, secondary resource materials such as fly ash, blast furnace slag, and bottom ash are increasingly used for alternative types of concrete binders, such as geopolymers. Because secondary resources may be highly variable from the perspective of geopolymers, it is

  9. Experimental results of combustion and desulphurization in fluidized bed. Implementation opportunities

    International Nuclear Information System (INIS)

    Dragos, L.; Jinescu, G.; Scarlat, N.

    1996-01-01

    Possibilities of both stationary fluidized bed combustion (SFBC) and circulating fluidized bed combustion (CFBC) technologies for desulfurization of Romanian coal-fired power plants have been studied since the 70's. The results of research on a 2 MWh SFBC semi-industrial pilot hot water boiler and an 1 MWh CFBC pilot plant are presented. 4 sorts of lignite (3 Romanian and 1 Albanian) are used in the study. The combustion efficiencies for SFBC are between 82 - 84% and for CFBC - between 84 - 87%. The heat transfer coefficients for lignite and peat coal have been determined for different zones, different levels of ash recirculation rate and various operating loads. Experiments with 2 sorts of sorbents: dolomite and limestone, under different temperature conditions and at Ca/S molar ratio 0.5 - 3.5 have been carried out. The temperature range for the maximum values of desulfurization efficiency is 840-870 o C for limestone and 820-860 o C for dolomite. The following efficiency values are obtained for lignite in the SFBC pilot plant: 1) over 80%, when using dolomite as a sorbent and the Ca/S molar ratio is greater than 2.5; 2) 75 - 90%, when limestone has been used and the Ca/S molar ratio is in the range 2-3. Desulfurization efficiency in CFBC plant for lignite using limestone is 80-93% for Ca/S ratio between 2 and 3. The necessity to commission a demonstrative installation with low pollutant emissions is pointed out. The Comanesti Power Plant has been chosen for this purpose. An old 75 t/h steam boiler will be replaced with 45 MWh CFBC boiler for combined heat and steam production. The overall estimated investment costs for this plant are about 6 million $US. 1 tabs., 5 refs

  10. Appendices 1-3 - the effects of combustion on ash and deposits from low rank coals

    Energy Technology Data Exchange (ETDEWEB)

    Ledger, R.C.; Ottrey, A.L.; Mackay, G.H.

    1985-12-01

    Thermomechanical analyses (TMA) of ashes derived from combustion of fourteen coal samples from Victorian and South Australian coalfields are presented in the results volumes of this report (Volume 2-4). This appendix describes the analytical equipment used, the modifications that were incorporated and the technique developed for analysis and interpretation of the data. To aid identification, limited numbers of analyses were performed on reference materials, the results of which are presented in this appendix. Analyses were performed on a modified Stanton Redcroft 790 series thermomechanical analyser. The aim was to identify components in the ashes and to gain an understanding of the sintering and fusion behaviour of the ashes up to temperatures encountered in large scale boilers. As part of the main project, ashes were also submitted to simultaneous Differential Thermal Analysis and Thermogravimetry (DTA-TG). For each coal burnt in this investigation the Test Bank 1 and precipitator ashes produced at a flame temperature of 1200/sup o/C and 3% excess oxygen were examined by TMA, as were ashes from tests at other flame temperatures and at 3% excess oxygen for four of the coals. This was to investigate the effects of variation in combustion conditions on ash properties. The results are presented in Volume 2-4 of this report as tables, giving details of events and assignments and as a formalised TMA pattern for each ash tested.

  11. Faecal-wood biomass co-combustion and ash composition analysis.

    Science.gov (United States)

    Somorin, Tosin Onabanjo; Kolios, Athanasios J; Parker, Alison; McAdam, Ewan; Williams, Leon; Tyrrel, Sean

    2017-09-01

    Fuel blending is a widely used approach in biomass combustion, particularly for feedstocks with low calorific value and high moisture content. In on-site sanitation technologies, fuel blending is proposed as a pre-treatment requirement to reduce moisture levels and improve the physiochemical properties of raw faeces prior to drying. This study investigates the co-combustion performance of wood dust: raw human faeces blends at varying air-to-fuel ratios in a bench-scale combustor test rig. It concludes with ash composition analyses and discusses their potential application and related problems. The study shows that a 50:50 wood dust (WD): raw human faeces (FC) can reduce moisture levels in raw human faeces by ∼40% prior to drying. The minimum acceptable blend for treating moist faeces without prior drying at a combustion air flow rate of 14-18 L/min is 30:70 WD: FC. For self-sustained ignition and flame propagation, the minimum combustion temperature required for conversion of the fuel to ash is ∼400 °C. The most abundant elements in faecal ash are potassium and calcium, while elements such as nickel, aluminium and iron are in trace quantities. This suggests the potential use of faecal ash as a soil conditioner, but increases the tendency for fly ash formation and sintering problems.

  12. Trends in the Rare Earth Element Content of U.S.-Based Coal Combustion Fly Ashes.

    Science.gov (United States)

    Taggart, Ross K; Hower, James C; Dwyer, Gary S; Hsu-Kim, Heileen

    2016-06-07

    Rare earth elements (REEs) are critical and strategic materials in the defense, energy, electronics, and automotive industries. The reclamation of REEs from coal combustion fly ash has been proposed as a way to supplement REE mining. However, the typical REE contents in coal fly ash, particularly in the United States, have not been comprehensively documented or compared among the major types of coal feedstocks that determine fly ash composition. The objective of this study was to characterize a broad selection of U.S. fly ashes of varied geological origin in order to rank their potential for REE recovery. The total and nitric acid-extractable REE content for more than 100 ash samples were correlated with characteristics such as the major element content and coal basin to elucidate trends in REE enrichment. Average total REE content (defined as the sum of the lanthanides, yttrium, and scandium) for ashes derived from Appalachian sources was 591 mg kg(-1) and significantly greater than in ashes from Illinois and Powder River basin coals (403 and 337 mg kg(-1), respectively). The fraction of critical REEs (Nd, Eu, Tb, Dy, Y, and Er) in the fly ashes was 34-38% of the total and considerably higher than in conventional ores (typically less than 15%). Powder River Basin ashes had the highest extractable REE content, with 70% of the total REE recovered by heated nitric acid digestion. This is likely due to the higher calcium content of Powder River Basin ashes, which enhances their solubility in nitric acid. Sc, Nd, and Dy were the major contributors to the total REE value in fly ash, based on their contents and recent market prices. Overall, this study shows that coal fly ash production could provide a substantial domestic supply of REEs, but the feasibility of recovery depends on the development of extraction technologies that could be tailored to the major mineral content and origins of the feed coal for the ash.

  13. Waste Water Treatment-Bed of Coal Fly Ash for Dyes and Pigments Industry

    OpenAIRE

    Syed Farman Ali Shah; Aziza Aftab; Noorullah Soomro; Mir Shah Nawaz; Kambiz Vafai

    2015-01-01

    The highly porous power plant waste ashes have been utilized to treat toxic effluent of a dyes manufacturing plant. An attempt has been made for the first time in Pakistan, to generate an effective and economically sound treatment facility for the toxic effluent of a dyes manufacturing plant. This is an indigenous bed which could replace expensive treatment facilities, such as reverse osmosis (RO), granulated activated carbon (GAC) bed, etc. The treatment efficiency was improved by coupling c...

  14. Experimental study of improvement on combustion control of fluidized bed combustion chamber; Ryudosho shokyakuro no nenshosei no kaizen ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Izumiya, T.; Baba, K.; Koshida, H.; Uetani, J.; Furuta, M.

    1998-10-29

    Nippon Steel Corporation has carried out an experimental study using the Yawata waste incinerator plant in order to improve combustion control of a fluidized bed combustion chamber. For controlling the forming of dioxin, combustion control is very important in addition to conventional methods. In this paper, we report two studies about improvements on combustion control. In the first study, we verified improvement on combustion control by modifying gas flow at the freeboard. The operational results of the experiments were studied using the numerical model of the combustion chamber. The modification of gas flow at freeboard was confirmed to be effective to obtain a compact design of fluidized bed combustion chamber for municipal waste. In the second, study we improved combustion control for sewage combustion with municipal waste. In burning municipal waste and sewage, it is especially required to take combustion control into careful consideration. In this experiment, we developed a new device for supplying sewage for the appropriate controlling combustion, and verified its effectiveness to combustion control and an effective reduction of dioxin. (author)

  15. Development of second-generation pressurized fluidized bed combustion process

    Energy Technology Data Exchange (ETDEWEB)

    Wolowodiuk, W.; Robertson, A. [Foster Wheeler Development Corp., Livingston, NJ (United States); Bonk, D. [Dept. of Energy, Morgantown, WV (United States)

    1995-12-01

    Under the sponsorship of the United States Department of Energy, Foster Wheeler Development Corporation, and its team members, Westinghouse, Gilbert/Commonwealth, and the Institute of Gas Technology are developing second-generation pressurized fluidized bed combustion technology capable of achieving net plant efficiency in excess of 45 percent based on the higher heating value of the coal. A three-phase program entails design and costing of a 500 MWe power plant and identification of developments needed to commercialize this technology (Phase 1), testing of individual components (Phase 2), and finally testing these components in an integrated mode (Phase 3). This paper briefly describes the results of the first two phases as well as the progress on the third phase. Since other projects which use the same technology are in construction or in negotiation stages-namely, the Power System Development Facility and the Four Rivers Energy Modernization Projects-brief descriptions of these are also included.

  16. Utilization of stabilized municipal waste combustion ash residues as construction material

    International Nuclear Information System (INIS)

    Shieh, C.S.

    1992-01-01

    Stabilized municipal waste combustion (MWC) ash residues were investigated for their potential as construction material that can be beneficially used in terrestrial and marine environments. End-use products, such as patio stones, brick pavers, solid blocks, and reef units, were fabricated and tested for their engineering and chemical characteristics. engineering feasibility and environmental acceptability of using stabilized ash residues as construction material are discussed in this paper. Ash samples were collected from two mass-burn facilities and one refuse derived fuel (RDF) facility in Florida

  17. Effect of additives in reducing ash sintering and slagging in biomass combustion applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liang

    2012-07-01

    The objective of this study was to investigate sintering and slagging behaviors of biofuels during combustion processes. Biofuels tested are derived from the agricultural sector, wood and furniture industry as well as from municipal sewage sludge. It was also the aim to test and evaluate additives that can prevent and abate biomass ash sintering by conducting laboratory and industrial scale tests. Sintering characteristics of sewage sludge ashes at elevated temperatures were investigated by means of different laboratory methods. Utilizing of phosphorus participation agents Al2(SO4)3 or Fe2(SO4)3 caused substantially high contents of aluminum or iron in the studied sewage sludge ashes, respectively. High initial melting temperatures over 1100 degrees C and low sintering tendencies were observed from the sewage sludge ashes rich in aluminum. It was related to presence and formation of the inert mineral phases such as aluminum oxide, quartz and calcium aluminum silicates in the aluminum rich sewage sludge ashes at elevated temperatures. A low melting temperature, about 994 degree C, was detected from the iron rich sewage sludge ash. Severe sintering of this sewage sludge ash was mainly due to generation of low temperature melting iron silicates, as results of interaction and re-assemblage of hematite (Fe2O3), quartz (SiO2) and alkali feldspars under heating. Fusion behaviors of corn cob ashes under rising temperatures were characterized. The work revealed that chemical compositions of corn cob ashes are dominated by potassium, silicon, chlorine and phosphorus. However, the relative concentrations of these principal elements are considerably different for three studied corn cob ashes, which have major influence on ash transformation reactions and sintering tendencies. Compared with the other two, the chemical composition of the Waimanalo corn cob (WCob) was characterized with the highest K/Cl, Si/(Ca+Mg) and (Si+P+K)/(Ca+Mg) molar ratios, which was favorable for

  18. Electrodialytic remediation of fly ash from co-combustion of wood and straw

    DEFF Research Database (Denmark)

    Chen, Wan; Jensen, Pernille Erland; Ottosen, Lisbeth M.

    2015-01-01

    The heavy metal content in fly ash from biomass combustion, such as straw, wood and sludge, often needs reducing before the ash can be used as fertilizer for agricultural land or as a component in the production of construction materials. In this study, fly ash from a boiler fueled with wood chips...... and straw was treated either by electrodialytic remediation (EDR) directly or by a combination of EDR and pre-wash with distilled water to investigate the possibilities of reducing the heavy metal content and reusing nutrients as fertilizer and bulk material in construction materials. Different experimental....../pre-wash-EDR treated ash mainly contained quartz, and the X-ray diffraction (XRD) peaks of K salts had disappeared. This shows that the potassium fertilizer potential was lost in the treated ashes, but the quartz mineral is beneficial in construction materials, such as ceramics. The K fertilizer could be recovered...

  19. Long-term leaching of nutrients and contaminants from wood combustion ashes

    DEFF Research Database (Denmark)

    Maresca, Alberto; Hyks, J.; Astrup, Thomas Fruergaard

    2018-01-01

    With increasing amounts of woody biomass being combusted for energy purposes worldwide, more wood ash is being generated and needs management. As an alternative to landfilling, residues may be utilised for liming and fertilising purposes on forest soils. Comprehensive evaluations of long-term lea......With increasing amounts of woody biomass being combusted for energy purposes worldwide, more wood ash is being generated and needs management. As an alternative to landfilling, residues may be utilised for liming and fertilising purposes on forest soils. Comprehensive evaluations of long......-term leaching from these residues are needed in order to assess potential environmental impacts associated with their utilisation. Two Danish wood ash samples, one fly ash and one mixed ash (a combination of fly ash and bottom ash), were evaluated in long-term percolation column tests (up to L/S ∼2000 L....../kg), in order to quantify the release of major, minor and trace metal(loid)s. While columns of three different lengths were used, the leaching of individual elements could be described as a function of the L/S ratio – irrespective of the column length. At L/S 1000 L/kg, the cumulative releases of K, S, Na, Ca...

  20. Characterization and electrodialytic treatment of wood combustion fly ash for the removal of cadmium

    International Nuclear Information System (INIS)

    Pedersen, A.J.

    2003-01-01

    Due to a high content of macronutrients and a potential liming capacity, recycling of ashes from biomass combustion to agricultural fields as fertilisers and/or for soil improvement is considered in Denmark and other countries utilising biomass as an energy source. However, the fly ash fractions especially contain amounts of the toxic heavy metal cadmium that may exceed the limiting values for agricultural utilisation given by the Danish Environmental Protection Agency. In this work the advances of using an electrodialytic remediation method to reduce the Cd content in wood combustion fly ash--for the aim of recycling--was described. Initial characterisation of the experimental ash showed that the Cd content exceeded the limiting values for agricultural use and therefore needed treatment before being recycled. The pH in the ash was very high (13.3), and the Cd was not soluble at these alkaline conditions. However, significant amounts of Cd could be extracted at neutral to alkaline conditions using an ammonium citrate solution as a desorption agent. Electrodialytic remediation experiments showed that, under optimised remediation conditions using a mixture of ammonium citrate (0.25 M) and NH 3 (1.25%) as an assisting agent, more than 70% of the initial Cd could be removed from the wood fly ash. The results also indicated that a continuous out-separation of Cd from the aqueous process solutions is possible. Thereby, recycling of the (nutrient rich) process solutions as well as of the remediated ash seems achievable

  1. Co-Combustion of Municipal Sewage Sludge and Hard Coal on Fluidized Bed Boiler WF-6

    Directory of Open Access Journals (Sweden)

    Rajczyk Rafał

    2014-12-01

    Full Text Available According to data of the Central Statistical Office, the amount of sludge produced in municipal wastewater treatment plants in 2010 amounted to 526000 Mg d.m. The forecast of municipal sewage sludge amount in 2015 according to KPGO2014 will reach 642400 Mg d.m. and is expected to increase in subsequent years. Significant amounts of sludge will create problems due to its utilization. In order to solve this problem the use of thermal methods for sludge utilization is expected. According to the National Waste Management Plan nearly 30% of sewage sludge mass should be thermally utilized by 2022. The article presents the results of co-combustion of coal and municipal sewage sludge in a bubbling fluidized bed boiler made by SEFAKO and located in the Municipal Heating Company in Morag. Four tests of hard coal and sewage sludge co-combustion have been conducted. Boiler performance, emissions and ash quality were investigated.

  2. Combustion of municipal solid wastes with oil shale in a circulating fluidized bed. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-30

    The problem addressed by our invention is that of municipal solid waste utilization. The dimensions of the problem can be visualized by the common comparison that the average individual in America creates in five years time an amount of solid waste equivalent in weight to the Statue of Liberty. The combustible portion of the more than 11 billion tons of solid waste (including municipal solid waste) produced in the United States each year, if converted into useful energy, could provide 32 quads per year of badly needed domestic energy, or more than one-third of our annual energy consumption. Conversion efficiency and many other factors make such a production level unrealistic, but it is clear that we are dealing with a very significant potential resource. This report describes research pertaining to the co-combustion of oil shale with solid municipal wastes in a circulating fluidized bed. The oil shale adds significant fuel content and also constituents that can possible produce a useful cementitious ash.

  3. Modern fluidized bed combustion in Ostrava-Karvina cogeneration plants

    Energy Technology Data Exchange (ETDEWEB)

    Mazac, V. [Energoprojekt Praha, Ostrava (Czechoslovakia); Novacek, A. [Moravskoslezske teplamy, Ostrava (Czechoslovakia); Volny, J. [Templamy Karvina (Czechoslovakia)

    1995-12-01

    The contemporary situation of our environment claims the sensitive approach to solving effective conversion of energy. Limited supplies of noble fuels and their prices evoke the need to use new combustion technologies of accessible fuels in given region without negative ecological influences. Energoproject participates in the preparation of the two projects in Ostrava-Karvin{acute a} black coal field in Czech Republic. The most effective usage of fuel energy is the combined of electricity and heat. If this physical principle is supported by a pressurized fluidized bed combustion (PFBC) one obtains a high electricity/heat ratio integrated steam-gas cycle on the basis of solid fuel. Cogeneration plant Toebovice is the dominant source (600 MW{sub th}) of Ostrava district heating system (1100 MW{sub th}). The high utilization of the installed output and utilization of the clean, compact and efficient of the PFBC technology is the principal but not the single reason for the selection of the Toebovice power plant as the first cogeneration plant for installation of the PFBC in Czech Republic. The boiler will burn black coal from the neighboring coal basin.

  4. Combustion of peanut shells in a cone-shaped bubbling fluidized-bed combustor using alumina as the bed material

    International Nuclear Information System (INIS)

    Arromdee, Porametr; Kuprianov, Vladimir I.

    2012-01-01

    Highlights: ► We propose burning of peanut shells in a conical fluidized bed using alumina sand. ► We examine hydrodynamic, combustion and emission characteristics of the reactor. ► High, over 99%, combustion efficiency is achievable. ► Emissions of CO and NO from the combustor meet the national emission limits. ► Composition of the bed material undergoes significant changes during the combustion. -- Abstract: This paper reports experimental studies on burning peanut shells in the conical fluidized-bed combustor using alumina sand as the fluidizing agent. Prior to combustion tests, hydrodynamic regimes and characteristics of a conical alumina–biomass bed were investigated under cold-state conditions for variable percentage of peanut shells in the mixture and static bed height. With selected particle sizes (300–500 μm) and static bed height (30 cm), alumina ensured bubbling fluidization regime of the bed at operating conditions specified for firing biomass. Combustion tests were performed at 60 kg/h and 45 kg/h fuel feed rates, while ranging excess air from 20% to 80% at a fixed combustor load. Temperature and gas concentrations (O 2 , CO, C x H y as CH 4 , and NO) were measured along radial and axial directions inside the reactor as well as at stack in order to characterize combustion and emission performance of the combustor for the ranges of operating conditions. For firing 60 kg/h peanut shells, excess air of 40% can be selected as an appropriate value ensuring high, about 99%, combustion efficiency and rather low emissions of CO and NO: 520 ppm and 125 ppm, respectively (both on a dry basis and at 6% O 2 ). With reducing combustor load, the combustion efficiency and emission characteristics were improved to a little extent. No evidence of bed agglomeration was found during 30-h combustion tests on this conical fluidized-bed combustor using alumina sand as the bed material. However, the timescale effect on the composition of the bed material was

  5. Retrofit design of rice husk feeding system in the production of amorphous silica ash in a pilot scale fluidized bed combustor

    International Nuclear Information System (INIS)

    Abdul, A.; Rozainee, M.; Anwar, J.; Wan Alwi, R.S.

    2010-01-01

    Full text: Rice husk is among the most important recovery resources for silica that is produced annually in huge quantities in many countries such as Malaysia which produces 2.38 (MT) of rice paddy. Rice husks accounts for 14-35 % of the weight of the paddy harvested, depending on the paddy variety and because of its abundance it poses serious environmental problems in the rice producing countries. Therefore, the thermo-chemical conversion of rice husks to useful silica ash by fluidized bed combustion is the proven and cost-effective technology for converting the renewable waste husks by making commercial use of this rice husk ash because of its self sustaining ability. However, feeding of rice husk into the reactor bed has become a difficult problem hindering the production of amorphous silica. This is due to the poor penetration and low bulk density as well as the flaky, abrasive and joined nature of rice husk. Most of the researches into fluidized bed combustion are on laboratory or bench scale and none had discussed pilot scale combustion of rice husk into amorphous silica. A recent attempt to solve this feeding problem from an experimental investigation in a bench-scale culminates into a pilot-scale fluidized bed combustor designed with a combined screw conveyor and an inclined pneumatic feeding by direct injection, yet the problem persists. This paper presents a retrofit design of the existing 0.5 m internal diameter pilot scale fluidized bed combustor by the use of combined screw feeding system. It is envisaged that at the end of the experimental investigation the retrofit design will address the problem associated with rice husk feeding in bubbling fluidized bed combustors. (author)

  6. High plant availability of phosphorus and low availability of cadmium in four biomass combustion ashes

    International Nuclear Information System (INIS)

    Li, Xiaoxi; Rubæk, Gitte H.; Sørensen, Peter

    2016-01-01

    For biomass combustion to become a sustainable energy production system, it is crucial to minimise landfill of biomass ashes, to recycle the nutrients and to minimise the undesirable impact of hazardous substances in the ash. In order to test the plant availability of phosphorus (P) and cadmium (Cd) in four biomass ashes, we conducted two pot experiments on a P-depleted soil and one mini-plot field experiment on a soil with adequate P status. Test plants were spring barley and Italian ryegrass. Ash applications were compared to triple superphosphate (TSP) and a control without P application. Both TSP and ash significantly increased crop yields and P uptake on the P-depleted soil. In contrast, on the adequate-P soil, the barley yield showed little response to soil amendment, even at 300–500 kg P ha"−"1 application, although the barley took up more P at higher applications. The apparent P use efficiency of the additive was 20% in ryegrass - much higher than that of barley for which P use efficiencies varied on the two soils. Generally, crop Cd concentrations were little affected by the increasing and high applications of ash, except for relatively high Cd concentrations in barley after applying 25 Mg ha"−"1 straw ash. Contrarily, even modest increases in the TSP application markedly increased Cd uptake in plants. This might be explained by the low Cd solubility in the ash or by the reduced Cd availability due to the liming effect of ash. High concentrations of resin-extractable P (available P) in the ash-amended soil after harvest indicate that the ash may also contribute to P availability for the following crops. In conclusion, the biomass ashes in this study had P availability similar to the TSP fertiliser and did not contaminate the crop with Cd during the first year. - Highlights: • Effects of four biomass ashes vs. a P fertiliser (TSP) on two crops were studied. • Ashes increased crop yields with P availability similar to TSP on P-depleted soil.

  7. High plant availability of phosphorus and low availability of cadmium in four biomass combustion ashes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaoxi, E-mail: Xiaoxi.Li@agro.au.dk; Rubæk, Gitte H.; Sørensen, Peter

    2016-07-01

    For biomass combustion to become a sustainable energy production system, it is crucial to minimise landfill of biomass ashes, to recycle the nutrients and to minimise the undesirable impact of hazardous substances in the ash. In order to test the plant availability of phosphorus (P) and cadmium (Cd) in four biomass ashes, we conducted two pot experiments on a P-depleted soil and one mini-plot field experiment on a soil with adequate P status. Test plants were spring barley and Italian ryegrass. Ash applications were compared to triple superphosphate (TSP) and a control without P application. Both TSP and ash significantly increased crop yields and P uptake on the P-depleted soil. In contrast, on the adequate-P soil, the barley yield showed little response to soil amendment, even at 300–500 kg P ha{sup −1} application, although the barley took up more P at higher applications. The apparent P use efficiency of the additive was 20% in ryegrass - much higher than that of barley for which P use efficiencies varied on the two soils. Generally, crop Cd concentrations were little affected by the increasing and high applications of ash, except for relatively high Cd concentrations in barley after applying 25 Mg ha{sup −1} straw ash. Contrarily, even modest increases in the TSP application markedly increased Cd uptake in plants. This might be explained by the low Cd solubility in the ash or by the reduced Cd availability due to the liming effect of ash. High concentrations of resin-extractable P (available P) in the ash-amended soil after harvest indicate that the ash may also contribute to P availability for the following crops. In conclusion, the biomass ashes in this study had P availability similar to the TSP fertiliser and did not contaminate the crop with Cd during the first year. - Highlights: • Effects of four biomass ashes vs. a P fertiliser (TSP) on two crops were studied. • Ashes increased crop yields with P availability similar to TSP on P-depleted soil

  8. Incineration as a treatment option for shredder light fractions (SLF) by a stationary fluidised bed combustion; Untersuchungen zur Verbrennung von Shredderleichtfraktionen in einer stationaeren Wirbelschicht

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Gaston

    2011-07-15

    In this paper the suitability of the stationary fluidised bed combustion as a treatment option for shredder light fractions (SLF) is discussed. This SLF, SLF coarse grain and SLF generated in a further mechanical treatment were burned. The results show a strong change in grain size distribution of the bed material during the combustion the SLF and SLF-coarse fractions. The formation of agglomerates significantly impaired the fluidization. The main reason for this effect is the high content of alkali and alkaline earth metals in the SLF. During the incineration of SLF generated by further mechanical treatment the change in grain size distribution declines much more slowly. This results from the separation of hard plastics with higher calcium contents during further mechanical processing. The tests also showed a complete burnout and a significant enrichment of metals in the solid combustion residues (fabric filter ash bed ash, cyclone ash). These residues represent a recycling concentrate, which needs to be open in the future. (orig.)

  9. Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

    KAUST Repository

    Andersen, Myrrha E.

    2016-10-19

    Pulverized bituminous coal was burned in a 10. W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28, 32, and 36%). Experiments were designed to produce flames with practically relevant stoichiometric ratios (SR. =1.2-1.4) and constant residence times (2.3. s). Size-classified fly ash samples were collected, and measurements focused on the soot, elemental carbon (EC), and organic carbon (OC) composition of the total and ultrafine (<0.6. μm) fly ash. Results indicate that although the total fly ash carbon, as measured by loss on ignition, was always acceptably low (<2%) with all three oxy-combustion conditions lower than air-combustion, the ultrafine fly ash for both air-fired and oxy-fired combustion conditions consists primarily of carbonaceous material (50-95%). Carbonaceous components on particles <0.6. μm measured by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation was supported by thermogravimetric analysis indicating that for the air, 28% oxy, and 32% oxy conditions, 14-71% of this material may be OC volatilizing between 100. C and 550. C with the remaining 29-86% being EC/soot. However, for the 36% oxy condition, OC may comprise over 90% of the ultrafine carbon with a much smaller EC/soot contribution. These data were interpreted by considering the effects of oxy-combustion on flame attachment, ignition delay, and soot oxidation of a bituminous coal, and the effects of these processes on OC and EC emissions. Flame aerodynamics and inlet oxidant composition may influence emissions of organic hazardous air pollutants (HAPs) from a bituminous coal. During oxy-coal combustion, judicious control of inlet oxygen concentration and placement may be used to minimize organic HAP and soot emissions.

  10. Determination of Plant-Available Nutrients in Two Wood Ashes: the Influence of Combustion Conditions

    Czech Academy of Sciences Publication Activity Database

    Perná, Ivana; Ochecová, P.; Száková, J.; Hanzlíček, Tomáš; Tlustoš, P.

    2016-01-01

    Roč. 47, 13/14 (2016), 1664-1674 ISSN 0010-3624 R&D Projects: GA MZe QI102A207 Institutional support: RVO:67985891 Keywords : combustion condition * crystal phases * fertilizer * plant-available nutrients * wood ash Subject RIV: DM - Solid Waste and Recycling Impact factor: 0.589, year: 2016

  11. Major and trace elements in coal bottom ash at different oxy coal combustion conditions

    CSIR Research Space (South Africa)

    Oboirien, BO

    2014-09-01

    Full Text Available This paper presents a detailed study on the effect of temperature on the concentration of 27 major and trace elements in bottom ash generated from oxy fuel-combustion. The major elements are Na, Mg, Al, K, Ca and Fe and the minor and trace elements...

  12. A CFD model for biomass combustion in a packed bed furnace

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Md. Rezwanul [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia); Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Ovi, Ifat Rabbil Qudrat [Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Naser, Jamal, E-mail: jnaser@swin.edu.au [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia)

    2016-07-12

    Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is the most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solid and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.

  13. Geochemistry of coals, coal ashes and combustion wastes from coal-fired power stations

    International Nuclear Information System (INIS)

    Vassilev, S.V.; Vassileva, C.G.

    1997-01-01

    Contents, concentration trends, and modes of occurrence of 67 elements in coals, coal ashes, and combustion wastes at eleven Bulgarian thermoelectric power stations (TPS) were studied. A number of trace elements in coal and coal ash have concentrations greater than their respective worldwide average contents (Clarke values). Trace elements are concentrated mainly in the heavy accessory minerals and organic matter in coal. In decreasing order of significance, the trace elements in coal may occur as: element-organic compounds; impurities in the mineral matter; major components in the mineral matter; major and impurity components in the inorganic amorphous matter; and elements in the fluid constituent. A number of trace elements in the waste products, similar to coal ashes, exceed known Clarke contents. Trace elements are mainly enriched in non-magnetic, heavy and fine-grained fractions of fly ash. They are commonly present as impurities in the glass phases, and are included in the crystalline components. Their accessory crystalline phases, element-organic compounds, liquid and gas forms, are of subordinate importance. Some elements from the chalcophile, lithophile and siderophile groups may release into the atmosphere during coal burning. For others, the combustion process appears to be a powerful factor causing their relative enrichment in the fly ash and rarely in the bottom ash and slag. 65 refs., 1 fig., 11 tabs

  14. Strategies to reduce gaseous KCl and chlorine in deposits during combustion of biomass in fluidised bed boilers

    Energy Technology Data Exchange (ETDEWEB)

    Kassman, Haakan

    2012-11-01

    Combustion of a biomass with an enhanced content of alkali and chlorine (Cl) can result in operational problems including deposit formation and superheater corrosion. The strategies applied to reduce such problems include co-combustion and the use of additives. In this work, measures were investigated in order to decrease the risk of superheater corrosion by reducing gaseous KCl and the content of chlorine in deposits. The strategies applied were sulphation of KCl by sulphur/sulphate containing additives (i.e. elemental sulphur (S) and ammonium sulphate (AS)) and co-combustion with peat. Both sulphation of KCl and capture of potassium (K) in ash components can be of importance when peat is used. The experiments were mainly performed in a 12 MW circulation fluidised bed (CFB) boiler equipped for research purposes but also in a full-scale CFB boiler. The results were evaluated by means of IACM (on-line measurements of gaseous KCl), conventional gas analysis, deposit and corrosion probe measurements and ash analysis. Ammonium sulphate performed significantly better than elemental sulphur. Thus the presence of SO{sub 3} (i.e. AS) is of greater importance than that of SO{sub 2} (i.e. S) for sulphation of gaseous KCl and reduction of chlorine in deposits. Only a minor reduction of gaseous KCl was obtained during co-combustion with peat although chlorine in the deposits was greatly reduced. This reduction was supposedly due to capture of K by reactive components from the peat ash in parallel to sulphation of KCl. These compounds remained unidentified. The effect of volatile combustibles on the sulphation of gaseous KCl was investigated. The poorest sulphation was attained during injection of ammonium sulphate in the upper part of the combustion chamber during the lowest air excess ratio. The explanation for this is that SO{sub 3} was partly consumed by side reactions due to the presence of combustibles. These experimental results were supported by modelling, although the

  15. Ash liberation from included minerals during combustion of pulverized coal: the relationship with char structure and burnout

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H.; Wall, T.; Liu, G.; Bryant, G. [University of Newcastle, Callaghan, NSW (Australia). CRC for Black Coal Utilization and Dept. of Chemical Engineering

    1999-12-01

    In this study, the float fraction ({lt} specific gravity of 2.0) of a size cut (63-90 {mu}m) bituminous coal was combusted in a drop tube furnace (DTF) at a gas temperature of 1300{degree}C under an atmosphere of air, to investigate the ash liberation at five coal burnoff levels (35.5%, 54.3%, 70.1%, 87.1% and 95.6%). The data indicated that char structure determines the ash liberation at different burnoff levels. Fragmentation of porous char was found to be the determinative mechanism for formation of fine ash during the early and middle stages of char combustion, while coalescence of included mineral matter determines the coarse ash formed in the later stages of combustion. The investigation confirmed that the char morphology and structure play a key role in determining char fragmentation, char burnout history, and the ash liberation during combustion. 35 refs., 5 figs., 2 tabs.

  16. Post-treatment of Fly Ash by Ozone in a Fixed Bed Reactor

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Melia, M. C.; Jensen, Anker Degn

    2009-01-01

    to be fast. A kinetic model has been formulated, describing the passivation of carbon, and it includes the stoichiometry of the ozone consumption (0.8 mol of O-3/kg of C) and an ineffective ozone loss caused by catalytic decomposition. The simulated results correlated well with the experimental data....... prevents the AEA to be adsorbed. In the present work, two fly ashes have been ozonated in a fixed bed reactor and the results showed that ozonation is a potential post-treatment method that can lower the AEA requirements of a fly ash up to 6 times. The kinetics of the carbon oxidation by ozone was found...

  17. Development of a fluidized bed agglomeration modeling methodology to include particle-level heterogeneities in ash chemistry and granular physics

    Science.gov (United States)

    Khadilkar, Aditi B.

    The utility of fluidized bed reactors for combustion and gasification can be enhanced if operational issues such as agglomeration are mitigated. The monetary and efficiency losses could be avoided through a mechanistic understanding of the agglomeration process and prediction of operational conditions that promote agglomeration. Pilot-scale experimentation prior to operation for each specific condition can be cumbersome and expensive. So the development of a mathematical model would aid predictions. With this motivation, the study comprised of the following model development stages- 1) development of an agglomeration modeling methodology based on binary particle collisions, 2) study of heterogeneities in ash chemical composition and gaseous atmosphere, 3) computation of a distribution of particle collision frequencies based on granular physics for a poly-disperse particle size distribution, 4) combining the ash chemistry and granular physics inputs to obtain agglomerate growth probabilities and 5) validation of the modeling methodology. The modeling methodology comprised of testing every binary particle collision in the system for sticking, based on the extent of dissipation of the particles' kinetic energy through viscous dissipation by slag-liquid (molten ash) covering the particles. In the modeling methodology developed in this study, thermodynamic equilibrium calculations are used to estimate the amount of slag-liquid in the system, and the changes in particle collision frequencies are accounted for by continuously tracking the number density of the various particle sizes. In this study, the heterogeneities in chemical composition of fuel ash were studied by separating the bulk fuel into particle classes that are rich in specific minerals. FactSage simulations were performed on two bituminous coals and an anthracite to understand the effect of particle-level heterogeneities on agglomeration. The mineral matter behavior of these constituent classes was studied

  18. The combustion of coal blends in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Boavida, Dulce; Abelha, Pedro; Gulyurtlu, Ibrahim; Cabrita, Isabel

    1999-07-01

    Combustion studies of five coals of different origin were carried out in a laboratory scale fluidised bed combustor. Five blends prepared by mixing two coals based on their petrological characterisation, in varying amounts, were selected to study the possibility of reduction NO{sub x}, N{sub 2}O and SO{sub 2} emissions. The results showed that some blends had the opposite behaviour concerning the release of NO{sub x} and SO{sub 2} in relation to parent coals, and the emissions were higher than expected. The N{sub 2}O amounts observed were, however, in almost all blends tested, lower than predicted values. With some blends, the mixing levels intended to reduce SO{sub 2} were not always found to correspond to those for simultaneous decrease of Nox. Most of the blends studied showed some evidence of interaction between them. Varying the proportion of the blend components was observed to alter the temperatures at which interactions were stronger.

  19. Importance of fragmentation on the steady state combustion of wood char in a bubbling fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Pinho, Carlos [Universidade do Porto (CEFT/FEUP), Porto (Portugal). Faculdade de Engenharia. Centro de Estudos de Fenomenos de Transporte], E-mail: ctp@fe.up.pt

    2010-07-01

    A simple mathematical model for the analysis of the steady state behavior of a bubbling fluidized bed burner is presented, with the main intention of evaluating the importance of the primary fragmentation of fuel particles on the performance of this type of burners. This model has pedagogical advantages because of its simplicity and easiness of application to the analysis of realistic situations. The model is based upon the classical models used for the study of batch combustion processes in fluidized bed reactors. Experimental data from studies of fluidized bed combustion of portuguese vegetable chars are used to support the analysis of the performance of a 1 m diameter fluidized bed combustor. (author)

  20. Ash related behaviour in staged and non-staged combustion of biomass fuels and fuel mixtures

    International Nuclear Information System (INIS)

    Becidan, Michaël; Todorovic, Dusan; Skreiberg, Øyvind; Khalil, Roger A.; Backman, Rainer; Goile, Franziska; Skreiberg, Alexandra; Jovovic, Aleksandar; Sørum, Lars

    2012-01-01

    The fate of selected elements (with focus on the important players in corrosion i.e. Na, K, Pb, Zn, Cl and S) are investigated for three biomasses (wood, demolition wood and coffee waste) and six mixtures of these as pellets both with and without air staging in a laboratory reactor. In order to get a complete overview of the combustion products, both online and offline analytical methods are used. Information is collected about: flue gas composition, particle (fly ash) size distribution and composition, bottom ash composition and melting properties. The main findings are: (1) complex interactions are taking place between the mixed fuels during combustion; (2) the mode of occurrence of an element as well as the overall structure of the fuel are important for speciation; (3) the pelletisation process, by bringing chemical elements into intimate contact, may affect partitioning and speciation; (4) staging and mixing might simultaneously have positive and negative effects on operation; (5) staging affects the governing mechanisms of fly ash (aerosols) formation. -- Highlights: ► Complex interactions are taking place between the mixed fuels during combustion. ► The mode of occurrence of an element as well as the overall structure of the fuel are important for speciation. ► The pelletisation process, by bringing chemical elements into intimate contact, may affect partitioning and speciation. ► Staging and mixing might simultaneously have positive and negative effects on operation. ► Staging affects the governing mechanisms of fly ash (aerosols) formation.

  1. Geochemical characterization of arsenic-rich coal-combustion ashes buried under agricultural soils and the release of arsenic

    International Nuclear Information System (INIS)

    Veselská, Veronika; Majzlan, Juraj; Hiller, Edgar; Peťková, Katarína; Jurkovič, Ľubomír; Ďurža, Ondrej; Voleková-Lalinská, Bronislava

    2013-01-01

    Highlights: ► Sources, mineralogy and mobility of As in coal-combustion ashes were investigated. ► After a dam failure in 1965, the spilled ashes were buried under agricultural soils. ► Primary carriers of As within coal-combustion ashes are aluminosilicate glasses. ► The most probable secondary carriers of labile As are oxyhydroxides of Si, Al, and Fe. ► Arsenic stored in ashes is a long-term contamination source for the environment. - Abstract: A combination of geochemical and mineralogical methods was used to determine the concentrations, mobility, and sources of As in coal-combustion ashes and soils in the vicinity of a thermal power plant at Nováky, central Slovakia. Fresh lagooned ash, ashes buried under agricultural soils for 45 a, and the overlying soils, contain high concentrations of As ranging from 61 to 1535 mg/kg. There is no differences in the water extractable percentages of As between the fresh lagooned ash and buried ashes, which range from 3.80% to 6.70% of the total As. This small amount of As may perhaps reside on the surfaces of the ash particles, as postulated in the earlier literature, but no evidence was found to support this claim. Electron microprobe analyses show that the dominant primary As carriers are the aluminosilicate glasses enriched in Ca and Fe. The acid NH 4 + -oxalate extraction hints that the oxyhydroxides of Si, Al, and Fe are the most probable secondary carriers of labile As. The X-ray absorption spectroscopy (XAS) analyses show that As in the lagooned and buried ashes occurs mostly as As(V). The long-term burial of the coal-combustion ash under agricultural soil did not cause any major change of its chemical composition or As lability compared to the fresh lagooned ash

  2. High-precision zircon U-Pb geochronology of astronomically dated volcanic ash beds from the Mediterranean Miocene

    NARCIS (Netherlands)

    Wotzlaw, Jörn Frederik; Hüsing, Silja K.; Hilgen, Frederik J.; Schaltegger, Urs

    2014-01-01

    Several orbitally tuned Miocene sedimentary sequences around the Mediterranean contain abundant intercalated volcanic ash beds. These sequences provide the rare opportunity to directly compare radioisotopic dating methods with independent and accurate deposition ages derived from astrochronology. We

  3. Bioextraction of copper and zinc from fly ash from coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wilczok, T; Cwalina, B; Chrostowska, D

    1986-02-01

    Results are evaluated of investigations carried out by the Institute of Chemistry and Physics of the Silesia Medical Academy in Sosnowiec into feasibility of bacterial leaching for utilization of fly ash from combustion of black coal. Fly ash separated by electrostatic precipitators in the Dolna Odra power plant fired with black coal was used. Copper content in the fly ash on the average was 0.012%, that of zinc was 0.025%. When Thiobacillus ferroxidans, Thiobacillus thiooxidans and bacteria separated from fly ash were used leaching efficiency after 21 days ranged from 69 to 87% in the case of copper and from 48 to 72% in the case of zinc. Origin of bacteria separated from fly ash was unclear. Autochthonous bacteria in the fly ash being leached increased efficiency of bacterial leaching. Effects of autochthonous bacteria were similar to those of the bacterial culture of Thiobacillus ferroxidans and Thiobacillus thiooxidans. Investigation results were shown in a table and 2 diagrams. 19 references.

  4. Incineration of a typical LWR combustible waste and analysis of the resulting ash

    International Nuclear Information System (INIS)

    Treat, R.L.; Lokken, R.O.; Schliebe, M.J.

    1983-05-01

    In this study 4540 kg (10,000 lb) of simulated nuclear power plant combustion wastes were burned in a controlled-air incinerators. The purpose of this work was to generate ashes suitable for solidification, the products of which will be analyzed to determine if they are suitable for disposal. Two different types of waste were burned: resin and simulated crud, and general trash (paper, plastics, wood, rubber, and cloth). Volume-reduction ratios (unburned waste: ash) were 13:1 and 22:1, respectively. Approximately 20% of the ash was lost due to adherence to incinerator walls and entrainment in the off-gas stream. Losses of the volatile species cesium and iodine were 79% and 100%, respectively. The ashes were not hygroscopic, but they exhibited a pH of 4.6 to 5.0 when water was added. Corrosion of mild steel drums would occur within this pH range. The ashes contained a significant quantity of clinkers haveing lengths as great as 20 cm (8 in.). Most of the clinkers were fully incinerated and easy to crush, suggesting that standard comminuting equipment should be effective in reducing the size of clinkers to allow their solidification with the fine ashes

  5. Factors affecting the amounts of emissions arising from fluidized bed combustion of solid fuels

    International Nuclear Information System (INIS)

    Horbaj, P.

    1996-01-01

    The factors affecting the amounts of nitrogen oxides (NO x ) and sulfur oxides (SO x , i.e. SO 2 + SO 3 ) formed during fluidized bed combustion of fossil fuels are analyzed using both theoretical concepts and experimental data. The factors treated include temperature, excess air, fuel parameters, pressure, degree of combustion gas recycling, combustion distribution along the combustion chamber height, and sulfur trapping processes for NO x , and the Ca/S ratio, fluidized layer height and fluidization rate, granulometry and absorbent type, fluidized layer temperature, and pressure during combustion for SO x . It is concluded that fluidized bed boilers are promising power generating facilities, mitigating the environmental burden arising from fossil fuel combustion. (P.A.). 12 figs., 9 refs

  6. Elemental analysis of ash residue from combustion of CCA treated wood waste before and after electrodialytic extraction

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Ottosen, Lisbeth M.

    2006-01-01

    Element distribution in a combined fly ash and bottom ash from combustion of copper chromate arsenate (CCA) treated wood waste was investigated by scanning electron microscopy (SEM/EDX) before and after electrodialytic extraction. The untreated ash contained various particles, including pieces...... of incompletely combusted wood rich in Cr and Ca, and irregular particles rich in Si, Al and K. Cr was also found incorporated in silica-based matrix particles. As was associated with Ca in porous (char) particles, indicating that Ca-arsenates had been formed during combustion. Cu was associated with Cr...... in the incompletely combusted wood pieces and was also found in almost pure form in a surface layer of some matrix particles – indicating surface condensation of volatile Cu species. In treated ash, Ca and As were no longer found together, indicating that Ca-arsenates had been dissolved due to the electrodialytic...

  7. Reprint of “Experiences in sulphur capture in a 30 MWth Circulating Fluidized Bed boiler under oxy-combustion conditions”

    International Nuclear Information System (INIS)

    Gómez, M.; Fernández, A.; Llavona, I.; Kuivalainen, R.

    2015-01-01

    CO 2 and SO 2 from fossil fuel combustion are contributors to greenhouse effect and acid rain respectively. Oxy-combustion technology produces a highly concentrated CO 2 stream almost ready for capture. Circulating Fluidized Bed (CFB) boiler technology allows in-situ injection of calcium-based sorbents for efficient SO 2 capture. CIUDEN's 30 MWth CFB boiler, supplied by Foster Wheeler and located at the Technology Development Centre for CO 2 Capture and Transport (es.CO 2 ) in Spain, is the first of its kind for executing test runs at large pilot scale under both air-combustion and oxy-combustion conditions. In this work, SO 2 emissions under different scenarios have been evaluated. Variables such as limestone composition, Ca/S molar ratio and bed temperature among others have been considered along different test runs in both air-combustion and oxy-combustion conditions to analyse its influence on SO 2 abatement. Fly and bottom ash, together with flue gas analysis have been carried-out. Desulphurization performance tests results are presented. - Highlights: • Sulphur capture efficiency (%) was higher in oxy-combustion compared to air-combustion in a 30 MW thermal CFB boiler using anthracite and limestone as sulphur sorbent. • For a Ca/S molar ratio higher than 2.6 there was barely any improvement on sulphur capture efficiency for both air-combustion and oxy-combustion conditions in a 30 MW thermal CFB boiler using anthracite and limestone as sulphur sorbent. • Optimum temperature for sulphur capture at a fixed Ca/S molar ratio is around 880–890 °C under oxy-combustion conditions and for anthracite coal with limestone as sorbent in a 30 MW thermal CFB boiler

  8. In Developping a Bench-Scale Circulating Fluidized Bed Combustor to Burn High Ash Brazilian Coal-Dolomites Mixtures

    Science.gov (United States)

    Ramírez Behainne, Jhon Jairo; Hory, Rogério Ishikawa; Goldstein, Leonardo; Bernárdez Pécora, Araí Augusta

    This work considers some of the questions in burning high ash Brazilian coal-dolomite mixtures in a bench-scale circulating fluidized bed combustor (CFBC). Experimental tests were performed with the CE4500 coal from Santa Catarina State, in southern Brazil, with a Sauter mean diameter d p =43 μm. The coal particles were mixed with dolomite particles of d p = 111 μm and this fuel mixture was fed into the circulating fluidized reactor, previously loaded with quartz sand particles of d p =353 μm. This inert material was previously heated by the combustion of liquefied petroleum gas up to the ignition temperature of the fuel mixture. The CFBC unit has a 100mm internal diameter riser, 4.0m high, as well as a 62.8mm internal diameter downcomer. The loop has a cyclone, a sampling valve to collect particles and a 62.8mm internal diameter L-valve to recirculate the particles in the loop. A screw feeder with a rotation control system was used to feed the fuel mixture to the reactor. The operational conditions were monitored by pressure taps and thermocouples installed along the loop. A data acquisition system showed the main operational conditions to control. Experimental tests performed put in evidence the problems found during bed operation, with special attention to the solids feed device, to the L-valve operation, to particle size, solids inventory, fluidized gas velocity, fuel mixture and recirculated solids feeding positions.

  9. Electrodialytic remediation of fly ash from co-combustion of wood and straw

    International Nuclear Information System (INIS)

    Chen, Wan; Jensen, Pernille E.; Ottosen, Lisbeth M.; Kirkelund, Gunvor M.

    2015-01-01

    The heavy metal content in fly ash from biomass combustion, such as straw, wood and sludge, often needs reducing before the ash can be used as fertilizer for agricultural land or as a component in the production of construction materials. In this study, fly ash from a boiler fueled with wood chips and straw was treated either by electrodialytic remediation (EDR) directly or by a combination of EDR and pre-wash with distilled water to investigate the possibilities of reducing the heavy metal content and reusing nutrients as fertilizer and bulk material in construction materials. Different experimental set-ups were tested for EDR treatment primarily of Cd and Pb as well as of Cu and Zn. Elemental contents such as K, P and Ni were compared in ash samples before and after treatment. The results showed that pre-washing caused an increase in total concentrations of most heavy metals because the highly soluble fraction, mainly KCl and K 2 SO 4 , was removed. After EDR treatment, the Cd concentration was reduced to below 2 mg kg −1 in all ash samples with high and stable average removal of above 95%, no matter how high the initial concentration was. The amount of Pb removed varied from 12% to 67%. Even though Pb was extracted from the ash samples, its concentrations in the treated ash samples were elevated due to the ash dissolution, except in the case of pre-washed ash treated in a two-compartment EDR cell, where the mass of Pb removed was the highest with a final concentration of about 100 mg kg −1 . The two-compartment EDR cell probably performed better due to a fast acidification process. In addition, this process was less energy-consuming. However, the fast acidification did in turn affect the leaching property of the treated ash, such as As and Ni, exceeding the limiting concentrations. The EDR/pre-wash-EDR treated ash mainly contained quartz, and the X-ray diffraction (XRD) peaks of K salts had disappeared. This shows that the potassium fertilizer potential was

  10. Leaching behavior of harmful components from cement solidities of fluidized-bed coal ash

    Energy Technology Data Exchange (ETDEWEB)

    Baba, T.; Fukuoka, H.; Shigemoto, N. [Fuji Clean Co., Kagawa (Japan)

    2008-07-15

    Solidifies of fluidized-bed fly ash with slag cement were prepared by hydrothermal treatment after adding gypsum, Na3PO{sub 4}, or Al2(SO{sub 4}){sub 3}. XRD analysis of the solidifies was performed and leaching behavior of Pb and F from the solidities was investigated. The fly ash-cement and fly ash-cement-gypsum solidifies showed rather high leaching concentration of F and Pb. The F leaching was explained by solubility products of a Ca(OH){sub 2} CaF2 system. The Pb leaching concentrations roughly agreed with the theoretical curve for hydroxo complexes of Pb, showing a strong dependence on pH. Addition of Na3PO{sub 4} and Al2(SO{sub 4}){sub 3}, to cement solidities gave katoite and aluminium phosphate, and ettringite, respectively, and these solidities showed lower leaching concentrations of F and Pb than the fly ash-cement and fly ash-cement-gypsum solidifies. Capture of F and Pb in crystalline components such as ettringite probably accounts for such leaching suppression.

  11. 14C age of the ash found in the peat bed of upland dog, Nakagawa-Gun, Hokkaido

    International Nuclear Information System (INIS)

    Igarashi, Yaeko; Kondo, Tsutomu; Fujiwara, Koichiro.

    1983-01-01

    The determination of the 14 C age of volcanic ash forming thin layer, which was found in a peat bed, was carried out. The samples were collected from the peat bed which distributes on the flat top of upland about 450m above sea level. The moor spread in the experimental plantation of the agricultural department of Hokkaido University. The thin layer of volcanic ash was found 20 cm deep in the peat bed and with about 1-3 cm thickness. The determination of 14 C age was made on the peat directly beneath the volcanic ash layer, along with the mineralogical studies. The obtained 14 C age was 480 480 +- 100 Y.B.P. (A.D. 1470), and this is presumed to be the age of eruption of the volcanic ash. The color of the ash was greenish yellow or orange in wet state, and grayish white in dry state. The volcanic ash was fine grained pumiceous, and round or nearly round grains predominate. By macroscopic observation, the grains were found to be composed of fibrous volcanic glass. The volcanic ash was well sorted, and the central grain size was 0.11 mm. Heavy liquid method was applied for the determination of heavy minerals. The weight percentage of heavy minerals was 1.59, and the characteristic of this ash was the entire absence of amphibole. Further investigation is necessary for clarifying the distribution of volcanic ash and the source of eruption. (Ishimitsu, A.)

  12. The influence of transport phenomena on the fluidized bed combustion of a single carbon particle

    NARCIS (Netherlands)

    Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1990-01-01

    The burning rate and temperature of the carbon particles are known to affect the efficiency of a fluidized bed combustor, and also the emission levels of undesired noxious components. The main results of an extensive study on the fluidized bed combustion behaviour of a single carbon particle [1] are

  13. Characterization and electrodialytic treatment of wood combustion fly ash for removal of cadmium

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul

    2003-01-01

    especially contain amounts of the toxic heavy metal cadmium that may exceed the limiting values for agricultural utilisation given by the Danish Environmental Protection Agency.In this work the advances of using an electrodialytic remediation method to reduce the Cd content in wood combustion fly ash...... conditions. However, significant amounts of Cd could be extracted at neutral to alkaline conditions using an ammonium citrate solution as a desorption agent.Electrodialytic remediation experiments showed that, under optimised remediation conditions using a mixture of ammonium citrate (0.25M) and NH"3 (1.......25%) as an assisting agent, more than 70% of the initial Cd could be removed from the wood fly ash. The results also indicated that a continuous out-separation of Cd from the aqueous process solutions is possible. Thereby, recycling of the (nutrient rich) process solutions as well as of the remediated ash seems...

  14. Fertilisers production from ashes after sewage sludge combustion - A strategy towards sustainable development.

    Science.gov (United States)

    Gorazda, Katarzyna; Tarko, Barbara; Wzorek, Zbigniew; Kominko, Halyna; Nowak, Anna K; Kulczycka, Joanna; Henclik, Anna; Smol, Marzena

    2017-04-01

    Sustainable development and circular economy rules force the global fertilizer industry to develop new phosphorous recovery methods from alternative sources. In this paper a phosphorus recovery technology from Polish industrial Sewage Sludge Ashes was investigated (PolFerAsh - Polish Fertilizers form Ash). A wet method with the use of mineral acid and neutralization was proposed. Detailed characteristic of SSA from largest mono-combustion plans were given and compared to raw materials used on the market. The technological factors associated with such materials were discussed. The composition of the extracts was compared to typical industrial phosphoric acid and standard values characterizing suspension fertilizers. The most favorable conditions for selective precipitation of phosphorus compounds were revealed. The fertilizers obtained also meet EU regulations in the case of the newly discussed Cd content. The process was scaled up and a flow mass diagram was defined. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Improved electrical efficiency and bottom ash quality on waste combustion plants. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Peter A.; Nesterov, I.; Boejer, M.; Hyks, J.; Astrup, T.; Kloeft, H.; Dam-Johansen, K.; Lundtorp, K.; Hedegaard Madsen, O.; Frandsen, F. (Technical Univ. of Denmark, Kgs. Lyngby (Denmark)); Mogensen, Erhardt (Babcock and Wilcox Voelund A/S, Glostrup (Denmark))

    2010-07-01

    Investigations making it possible to evaluate and further develop concepts to improve electrical efficiency in a waste combustion plant were performed. Furthermore, one objective of the study was to investigate the possibilities of improving waste bottom ash leaching properties by use of a rotary kiln treatment. The project work included construction of a bench-scale rotary kiln, performing ash rotary kiln treatment experiments, conducting gas suction probe measurements on a waste incineration plant and making some concept evaluations. The influence of the rotary kiln thermal treatment on the leaching of Ca, Al, Si, Mg, Ba, Sr, Cl, Cu, Pb, Zn, Cr, Mo, sulfate, DOC and carbonate was determined. As a result of these tests, the rotary kiln thermal treatment of bottom ashes can be recommended for reducing the leaching of Cu, Pb, Cl, Zn and DOC; however, an increased leaching of Cr and Mo should be expected. The combustion conditions above the grate of a waste incineration plant were investigated and the release and concentration of volatile ash species in the flue gas such as Cl, Na, K, Ca, Pb, Zn and S were measured. The conducted measurements show that flue gas from grate sections 3 and 4 can produce a sufficiently hot flue gas that contains only low concentrations of corrosive species, and therefore can be used to increase superheater temperatures. Implementation of the so-called flue gas split concept together with other steam circle modifications on a waste combustion plant, and using a reasonable increase in final steam temperature from 400 to 500 deg. C, have the potential to increase electrical efficiency from 24 to 30% (with respect to lower fuel heating value) in a waste combustion plant. (Author)

  16. Polycyclic aromatic hydrocarbons and other organic compounds in ashes from biomass combustion

    Czech Academy of Sciences Publication Activity Database

    Straka, Pavel; Havelcová, Martina

    2012-01-01

    Roč. 9, č. 4 (2012), s. 481-490 ISSN 1214-9705 R&D Projects: GA MZe QI102A207 Institutional research plan: CEZ:AV0Z30460519 Keywords : biomass combustion * ash * PAHs Subject RIV: GD - Fertilization, Irrigation, Soil Processing Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/materialy/acta_content/2012_04/6.Straka_%20Havelcova.pdf

  17. Immersion Freezing of Coal Combustion Ash Particles from the Texas Panhandle

    Science.gov (United States)

    Whiteside, C. L.; Tobo, Y.; Mulamba, O.; Brooks, S. D.; Mirrielees, J.; Hiranuma, N.

    2017-12-01

    Coal combustion aerosol particles contribute to the concentrations of ice-nucleating particles (INPs) in the atmosphere. Especially, immersion freezing can be considered as one of the most important mechanisms for INP formation in supercooled tropospheric clouds that exist at temperatures between 0°C and -38°C. The U.S. contains more than 550 operating coal-burning plants consuming 7.2 x 108 metric tons of coal (in 2016) to generate a total annual electricity of >2 billion MW-h, resulting in the emission of at least 4.9 x 105 metric tons of PM10 (particulate matter smaller than 10 µm in diameter). In Texas alone, 19 combustion plants generate 0.15 billion MW-h electricity and >2.4 x 104 metric tons of PM10. Here we present the immersion freezing behavior of combustion fly ash and bottom ash particles collected in the Texas Panhandle region. Two types of particulate samples, namely electron microscopy on both ash types will also be presented to relate the crystallographic and chemical properties to their ice nucleation abilities.

  18. Occurrence of bromine in fluidised bed combustion of solid recovered fuel

    Energy Technology Data Exchange (ETDEWEB)

    Vainikka, P.

    2011-12-15

    Corrosive ash species are the single most important factor limiting the electric efficiency of steam boiler plants fired with waste or biomass. Chlorine has been found to have a central role in the chemistry involved as it reduces the melting temperature of ash, forms corrosive vapour and gas species in the furnace and halogenated deposits on boiler heat transfer surfaces. In this context chlorine has been extensively researched. At the time of writing this thesis there was hardly any published data available on the occurrence of bromine (Br) in the aforementioned context. The objective of this work was to review the occurrence of bromine in solid fuels and characterise the behaviour of bromine in full-scale fluidised bed combustion. The review on the occurrence of bromine in solid fuels revealed that in anthropogenic wastes bromine is mainly found in connection to flame retarded substances. Several weight percentages of bromine can be found in plastics treated with brominated flame retardants (BFRs). Bromine is typically found some 100-200 mg kg-1 in mixed municipal solid wastes (MSW). Bromine may be enriched in fuels with high share of plastics, such as solid recovered fuel (SRF) or refuse derived fuel (RDF). Up to 2000 mg kg-1 was found as a monthly average in SRF, typical levels being 20-200 mg kg-1. Wastewater sludge from paper mills may contain bromine 20-100 mg kg-1 due the use of bromine based biocides. In other fuels bromine may be found in significant amounts in marine influenced coal deposits and peat as well as in biomass treated with brominated pesticides. In the experimental part SRF, spruce bark and wastewater sludge from a paper mill were co-fired in a full- scale bubbling fluidised bed (BFB) boiler, and the collected fuels, aerosols and waterwall deposits were analysed with the focus on the fate of bromine. Bromine was mainly found to form water soluble high vapour pressure alkali metal halides in the furnace - in the form of KBr(g) and NaBr(g) as

  19. Experimental studies on combustion of composite biomass pellets in fluidized bed.

    Science.gov (United States)

    Guo, Feihong; Zhong, Zhaoping

    2017-12-01

    This work presents studies on the combustion of Composite Biomass Pellets (CBP S ) in fluidized bed using bauxite particles as the bed material. Prior to the combustion experiment, cold-flow characterization and thermogravimetric analysis are performed to investigate the effect of air velocity and combustion mechanism of CBP S . The cold-state test shows that CBPs and bauxite particles fluidize well in the fluidized bed. However, because of the presence of large CBPs, optimization of the fluidization velocity is rather challenging. CBPs can gather at the bottom of the fluidized bed at lower gas velocities. On the contrary, when the velocity is too high, they accumulate in the upper section of the fluidized bed. The suitable fluidization velocity for the system in this study was found to be between 1.5-2.0m/s. At the same time, it is found that the critical fluidization velocity and the pressure fluctuation of the two-component system increase with the increase of CBPs mass concentration. The thermogravimetric experiment verifies that the combustion of CBPs is a first-order reaction, and it is divided into three stages: (i) dehydration, (ii) release and combustion of the volatile and (iii) the coke combustion. The combustion of CBPs is mainly based on the stage of volatile combustion, and its activation energy is greater than that of char combustion. During the combustion test, CBP S are burned at a 10kg/h feed rate, while the excess air is varied from 25% to 100%. Temperatures of the bed and flue gas concentrations (O 2 , CO, SO 2 and NO) are recorded. CBPs can be burnt stably, and the temperature of dense phase is maintained at 765-780°C. With the increase of the air velocity, the main combustion region has a tendency to move up. While the combustion is stable, O 2 and CO 2 concentrations are maintained at about 7%, and 12%, respectively. The concentration of SO 2 in the flue gas after the initial stage of combustion is nearly zero. Furthermore, NO concentration

  20. Fluidized combustion of beds of large, dense particles in reprocessing HTGR fuel

    International Nuclear Information System (INIS)

    Young, D.T.

    1977-03-01

    Fluidized bed combustion of graphite fuel elements and carbon external to fuel particles is required in reprocessing high-temperature gas-cooled reactor (HTGR) cores for recovery of uranium. This burning process requires combustion of beds containing both large particles and very dense particles as well as combustion of fine graphite particles which elutriate from the bed. Equipment must be designed for optimum simplicity and reliability as ultimate operation will occur in a limited access ''hot cell'' environment. Results reported in this paper indicate that successful long-term operation of fuel element burning with complete combustion of all graphite fines leading to a fuel particle product containing <1% external carbon can be performed on equipment developed in this program

  1. Co-combustion of risk husk with coal in a fluidized bed

    International Nuclear Information System (INIS)

    Ghani, A.K.; Alias, A.B.; Savory, R.M.; Cliffe, K.R.

    2006-01-01

    Power generation from biomass is an attractive technology which utilizes agricultural residue waste. In order to explain the behavior of biomass-fired fluidized bed incinerator, biomass sources from agricultural residues (rice husk) was co-fired with coal in a 0.15 m diameter and 2.3 m high fluidized bed combustor. The combustion efficiency and CO emissions were studied and compared with those for pure coal combustion. Biomass waste with up to 70% mass fraction can be co-combusted in a fluidized bed combustor designed for coal combustion with a maximum drop of efficiency of 20% depending upon excess air levels. CO levels fluctuated between 200-700 ppm were observed when coal is added. It is evident from this research that efficient co-firing of rice husk with coal can be achieved with minimum modification of existing coal-fired boilers. (Author)

  2. Volatiles combustion in fluidized beds. Final technical report, 4 September 1992--4 June 1995

    Energy Technology Data Exchange (ETDEWEB)

    Pendergrass, R.A. II; Raffensperger, C.; Hesketh, R.P.

    1996-02-29

    The goal of this project is to investigate the conditions in which volatiles will burn within both the dense and freeboard regions of fluidized beds. Experiments using a fluidized bed operated at incipient fluidization are being conducted to characterize the effect of particle surface area, initial fuel concentration, and particle type on the inhibition of volatiles within a fluidized bed. A review of the work conducted under this grant is presented in this Final Technical Report. Both experimental and theoretical work have been conducted to examine the inhibition of the combustion by the fluidized bed material, sand. It has been shown that particulate phase at incipient fluidization inhibits the combustion of propane by free radical destruction at the surface of sand particles within the particulate phase. The implications of these findings is that at bed temperatures lower than the critical temperatures, gas combustion can only occur in the bubble phase or at the top surface of a bubbling fluidized bed. In modeling fluidized bed combustion this inhibition by the particulate phase should be included.

  3. Immobilization and encapsulation during vitrification of incineration ashes in a coke bed furnace

    International Nuclear Information System (INIS)

    Kuo, Y.-M.; Lin, T.-C.; Tsai, P.-J.

    2006-01-01

    A real-scale coke bed furnace system has been successfully applied to vitrify the incineration ashes into glassy slags. The object of this research was to evaluate the effect of the system on the immobilization of metal species in the slag. Ashes and slag specimens were tested to identify their metal phase distribution following a sequential extraction procedure. The mobility of Al, Ca, Cd, Cr, Mg, Mn and Pb was noticeably reduced by vitrification. An important implication is the reduction of Cr 6+ to Cr 3+ along with its immobilization with this coke bed furnace. The Ni and Zn contents were relatively low in slag, indicating that their availability of mobile phases in ashes was reduced during vitrification. The XRD analyses identified the major crystalline phase in slag as akermanite, which is inert and helpful in metal immobilization. The phase distribution analysis also contributed to verify that the incorporation of Ca and Mg enhanced the encapsulation in the slag matrix. The low oxygen content in slag made the structure of silicate resistant to the proton-promoted attack and also enhanced the mobility reduction of matrix elements (Ca, Mg and Al) in the moderately reducible phase and also contributed to the immobilization of other metal species. However, the properties of slag also deserve further studies to ensure its long-term stability and safety

  4. Coal combustion by-product quality at two stoker boilers: Coal source vs. fly ash collection system design

    Energy Technology Data Exchange (ETDEWEB)

    Mardon, Sarah M. [Kentucky Department for Environmental Protection, Division of Water, Frankfort, KY 40601 (United States); Hower, James C. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); O' Keefe, Jennifer M.K. [Morehead State University, Department of Physical Sciences, Morehead, KY 40351 (United States); Marks, Maria N. [Environmental Consulting Services, Lexington, KY 40508 (United States); Hedges, Daniel H. [University of Kentucky, Department of Earth and Environmental Sciences, Lexington, KY 40506 (United States)

    2008-09-15

    Fly ashes from two stoker boilers burning Pennsylvanian Eastern Kentucky high volatile A bituminous coal blends were examined for their petrology and chemistry. The source coals have similar trace element contents. One of the ash collection systems was retrofitted with a baghouse (fabric filter) system, collecting a finer fly ash at a cooler flue gas temperature than the plant that has not been reconfigured. The baghouse ash has a markedly higher trace element content than the coarser fly ash from the other plant. The enhanced trace element content is most notable in the As concentration, reaching nearly 9000 ppm (ash basis) for one of the collection units. Differences in the ash chemistry are not due to any substantial differences in the coal source, even though the coal sources were from different counties and from different coal beds, but rather to the improved pollution control system in the steam plant with the higher trace element contents. (author)

  5. Heavy metals behaviour during mono-combustion and co-combustion of sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M. Helena; Abelha, Pedro; Olieveira, J.F. Santos; Gulyurtlu, Ibrahim; Cabrita, Isabel [INETI-DEECA, Lisboa (Portugal)

    2005-03-01

    This paper presents the study of the combustion of granular dry sewage sludge performed on a pilot fluidized bed system. The results of mono-combustion of sludge and co-combustion with coal were compared with those of coal combustion for ash partitioning, the formation of gaseous pollutants and heavy metals behaviour. It was found that the mineral matter of sludge was essentially retained as bottom ashes. The production of fines ashes was small during the mono-combustion due to the tendency of coal to produce fine ashes which also contained unburned char. The degree of heavy metal volatilization was found to be slightly higher during co-combustion than in mono-combustion; however, most of them were retained in ashes and their emissions were found to be below the regulated levels. Hg was completely volatilized; however, during combustion trials involving coal it was captured by cyclone ashes at temperatures below 300 deg C. During sludge mono-combustion the retention of Hg in cyclone ashes containing low LOI was not enough to decrease emissions below the regulated levels; hence, it is necessary to install dedicated flue gas treatment for Hg removal. The leachability and ecotoxicity of sludge and ashes was compared with the new regulatory limits for landfill disposal in the EU. It was found that the release of organic matter and heavy metals found in the sludge was low from granular bed ashes; hence, except for sulphate release, bed ashes were converted into inert and non-ecotoxic materials. Ashes from test with limestone and cyclone ashes seemed to be more problematic because of pH effects and contamination with steel corrosion products. The recovery and reutilization of sludge bed ashes could, therefore, be possible, as long as the release of sulphate do not interfere with the process.

  6. A scanning electron microscopy study of ash, char, deposits and fuels from straw combustion and co-combustion of coal and straw

    Energy Technology Data Exchange (ETDEWEB)

    Sund Soerensen, H.

    1998-07-01

    The SEM-study of samples from straw combustion and co-combustion of straw and coal have yielded a reference selection of representative images that will be useful for future comparison. The sample material encompassed potential fuels (wheat straw and grain), bottom ash, fly ash and deposits from straw combustion as well as fuels (coal and wheat straw), chars, bottom ash, fly ash and deposits from straw + coal co-combustion. Additionally, a variety of laboratory ashes were studied. SEM and CCSEM analysis of the samples have given a broad view of the inorganic components of straw and of the distribution of elements between individual ash particles and deposits. The CCSEM technique does, however, not detect dispersed inorganic elements in biomass, so to get a more complete visualization of the distribution of inorganic elements additional analyses must be performed, for example progressive leaching. In contrast, the CCSEM technique is efficient in characterizing the distribution of elements in ash particles and between ash fractions and deposits. The data for bottom ashes and fly ashes have indicated that binding of potassium to silicates occurs to a significant extent. The silicates can either be in the form of alumino-silicates or quartz (in co-combustion) or be present as straw-derived amorphous silica (in straw combustion). This process is important for two reasons. One is that potasium lowers the melting point of silica in the fly ash, potentially leading to troublesome deposits by particle impaction and sticking to heat transfer surfaces. The other is that the reaction between potassium and silica in the bottom ash binds part of the potassium meaning that it is not available for reaction with chlorine or sulphur to form KCl or K{sub 2}SO{sub 4}. Both phases are potentially troublesome because they can condense of surfaces to form a sticky layer onto which fly ash particles can adhere and by inducing corrosion beneath the deposit. It appears that in the studied

  7. A comparison of circulating fluidised bed combustion and gasification power plant technologies for processing mixtures of coal, biomass and plastic waste

    International Nuclear Information System (INIS)

    McIlveen-Wright, D.R.; Huang, Y.; McMullan, J.T.; Pinto, F.; Franco, C.; Gulyurtlu, I.; Armesto, L.; Cabanillas, A.; Caballero, M.A.; Aznar, M.P.

    2006-01-01

    Environmental regulations concerning emission limitations from the use of fossil fuels in large combustion plants have stimulated interest in biomass for electricity generation. The main objective of the present study was to examine the technical and economic viability of using combustion and gasification of coal mixed with biomass and plastic wastes, with the aim of developing an environmentally acceptable process to decrease their amounts in the waste stream through energy recovery. Mixtures of a high ash coal with biomass and/or plastic using fluidised bed technologies (combustion and gasification) were considered. Experiments were carried out in laboratory and pilot plant fluidised bed systems on the combustion and air/catalyst and air/steam gasification of these feedstocks and the data obtained were used in the techno-economic analyses. The experimental results were used in simulations of medium to large-scale circulating fluidised bed (CFB) power generation plants. Techno-economic analysis of the modelled CFB combustion systems showed efficiencies of around 40.5% (and around 46.5% for the modelled CFB gasification systems) when fuelled solely by coal, which were only minimally affected by co-firing with up to 20% biomass and/or wastes. Specific investments were found to be around $2150/kWe to $2400/kWe ($1350/kWe to $1450/kWe) and break-even electricity selling prices to be around $68/MWh to $78/MWh ($49/MWh to $54/MWh). Their emissions were found to be within the emission limit values of the large combustion plant directive. Fluidised bed technologies were found to be very suitable for co-firing coal and biomass and/or plastic waste and to offer good options for the replacement of obsolete or polluting power plants. (author)

  8. Ash deposition and high temperature corrosion at combustion of aggressive fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hede Larsen, O [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark); Henriksen, N [Elsamprojekt A/S, Faelleskemikerne, Fredericia (Denmark)

    1996-12-01

    In order to reduce CO{sub 2} emission, ELSAM is investigating the possibilities of using biomass - mainly straw - for combustion in high efficiency power plants. As straw has very high contents of chlorine and potassium, a fuel with high corrosion and ash deposition propensities has been introduced. ELSAM has investigated 3 ultra supercritical boiler concepts for combustion of straw alone or together with coal: (1) PF boilers with a relatively low share of straw, (2) CFB boilers with low to high share of straw and (3) vibrating grate boilers with 100% straw. These investigations has mainly been full-scale tests with straw fed into existing boilers. Corrosion tests have been performed in these boilers using temperature regulated probes and in-plant test tubes in existing superheaters. The corrosion has been determined by detailed measurements of wall thickness reduction and light optical microscopic measurements of the material degradation due to high temperature corrosion. Corrosion mechanisms have been evaluated using SEM/EDX together with thermodynamical considerations based on measurements of the chemical environment in the flue gas. Ash deposition is problematic in CFB boilers and in straw fired boilers, especially in years with high potassium and chlorine content of the straw. This ash deposition also is related to condensation of KCl and can probably only be handled by improved cleaning devices. (EG)

  9. Formation of chlorinated organic compounds in fluidized bed combustion of recycled fuels; Kloorattujen orgaanisten yhdisteiden muodostuminen kierraetyspolttoaineiden leijukerrospoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Vesterinen, R.; Kallio, M.; Kirjalainen, T.; Kolsi, A.; Merta, M. [VTT Energy, Jyvaeskylae (Finland)

    1997-10-01

    Four tests of co-combustion of recycled fuels (REP) with peat and coal in the 15 kW fluidized bed reactor were performed. The recycled fuel was so-called dry fraction in four vessels sampling at Keltinmaeki. In three tests a part of peat energy was replaced with coal. The mixtures were prepared so that in all mixtures 25 % of energy was recycled fuel and 75 % was either peat or the mixture of peat and coal. The concentrations of polyaromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and chlorophenols decreased with increasing part of coal due to the increasing sulphur/chlorine ratio. Principal Component Analysis (PCA) and Partial Least Square regression analysis (PLS) showed that the chlorine, copper and sulphur contents of the fuel effected most on the concentrations of chlorophenols, chlorobenzenes, PCBs and PCDDs/PCDFs. Other variables influencing on a model were the lead concentration and the sulphur/chlorine ratio in fuel and the hydrogen chloride concentration of the flue gas. The concentrations of chlorophenols and chlorobenzenes were also significant for PCDD/PCDF concentrations in flue gas. The sulphur, chlorine, copper and chromium contents in fly ash and the temperature of the reactor influenced on the chlorophenol, chlorobenzene, PCB and PCDD/PCDF concentrations in fly ash. The chlorophenol and chlorobenzene contents in fly ash, the sulphur/chlorine ratio and the lead content in fuel, the sulphur dioxide, hydrogen chloride and carbon monoxide concentrations in flue gas had also influence on PCDD/PCDF concentrations in fly ash

  10. Advanced air staging techniques to improve fuel flexibility, reliability and emissions in fluidized bed co-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Aamand, Lars-Erik; Leckner, Bo [Chalmers Technical Univ., Goeteborg (Sweden); Luecke, Karsten; Werther, Joachim [Technical Univ. of Hamburg-Harburg (Germany)

    2001-12-01

    A joint research project between the Technical University of Hamburg-Harburg and Chalmers Technical University. For operation under co-combustion the following results should be considered: The high ash content of the sewage sludge results in significantly increased ash flows. Although high alkali metal concentrations are found in the sewage sludge ash, no critical concentrations were reached and tendencies to fouling were not observed. The trace metal input rises with increased sludge fraction. However, emissions of metal compounds were well below legal limits. The trace metals tend to accumulate on the fly ash. In general, very low fuel nitrogen conversions to NO and N{sub 2}O of 2 - 4 % are achievable. With coal as a base fuel alternative air staging with secondary air supply after solids separation attains even lower NO emissions than normal staging without strongly affecting CO and SO{sub 2} emissions. Alternative staging also reduces N{sub 2}O emissions. An optimum for the excess air ratio in the riser of 1.05 was found for a total excess air ratio of 1.2. The higher the volatile content of the fuel is, the less effective the NO reduction due to air staging becomes. The measurements suggest that the optimum gas residence time regarding the emissions in CFB combustors is around 6 to 7 s. These times are achieved in commercial scale plants due to their large cyclones that perhaps partly can replace a large afterburner chamber. The circulating fluidized bed boiler can be operated in a very flexible way with various fuel mixtures up to an energy fraction of sludge of 25% without exceeding legal emission limits.

  11. Influence of carbonation under oxy-fuel combustion flue gas on the leachability of heavy metals in MSWI fly ash.

    Science.gov (United States)

    Ni, Peng; Xiong, Zhuo; Tian, Chong; Li, Hailong; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

    2017-09-01

    Due to the high cost of pure CO 2 , carbonation of MSWI fly ash has not been fully developed. It is essential to select a kind of reaction gas with rich CO 2 instead of pure CO 2 . The CO 2 uptake and leaching toxicity of heavy metals in three typical types of municipal solid waste incinerator (MSWI) fly ash were investigated with simulated oxy-fuel combustion flue gas under different reaction temperatures, which was compared with both pure CO 2 and simulated air combustion flue gas. The CO 2 uptake under simulated oxy-fuel combustion flue gas were similar to that of pure CO 2 . The leaching concentration of heavy metals in all MSWI fly ash samples, especially in ash from Changzhou, China (CZ), decreased after carbonation. Specifically, the leached Pb concentration of the CZ MSWI fly ash decreased 92% under oxy-fuel combustion flue gas, 95% under pure CO 2 atmosphere and 84% under the air combustion flue gas. After carbonation, the leaching concentration of Pb was below the Chinese legal limit. The leaching concentration of Zn from CZ sample decreased 69% under oxy-fuel combustion flue gas, which of Cu, As, Cr and Hg decreased 25%, 33%, 11% and 21%, respectively. In the other two samples of Xuzhou, China (XZ) and Wuhan, China (WH), the leaching characteristics of heavy metals were similar to the CZ sample. The speciation of heavy metals was largely changed from the exchangeable to carbonated fraction because of the carbonation reaction under simulated oxy-fuel combustion flue gas. After carbonation reaction, most of heavy metals bound in carbonates became more stable and leached less. Therefore, oxy-fuel combustion flue gas could be a low-cost source for carbonation of MSWI fly ash. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Fluidised bed gasification of high-ash South African coals: An experimental and modelling study

    CSIR Research Space (South Africa)

    Engelbrecht, AS

    2011-11-01

    Full Text Available model (CeSFaMB). The predictive capability of the model was analysed in terms of the degree of variation between experimental and simulated results for each test. The calibrated model was used to design a 15 MW fluidised bed coal gasifier...-scale BFBG are given in Figure 1 and Table 1. Process description Coal, air, oxygen and steam are the input streams to the process which produce the output streams: gas and char (ash). Coal is fed to the gasifier by means of a screw conveyor at a...

  13. Applied Gaussian Process in Optimizing Unburned Carbon Content in Fly Ash for Boiler Combustion

    Directory of Open Access Journals (Sweden)

    Chunlin Wang

    2017-01-01

    Full Text Available Recently, Gaussian Process (GP has attracted generous attention from industry. This article focuses on the application of coal fired boiler combustion and uses GP to design a strategy for reducing Unburned Carbon Content in Fly Ash (UCC-FA which is the most important indicator of boiler combustion efficiency. With getting rid of the complicated physical mechanisms, building a data-driven model as GP is an effective way for the proposed issue. Firstly, GP is used to model the relationship between the UCC-FA and boiler combustion operation parameters. The hyperparameters of GP model are optimized via Genetic Algorithm (GA. Then, served as the objective of another GA framework, the predicted UCC-FA from GP model is utilized in searching the optimal operation plan for the boiler combustion. Based on 670 sets of real data from a high capacity tangentially fired boiler, two GP models with 21 and 13 inputs, respectively, are developed. In the experimental results, the model with 21 inputs provides better prediction performance than that of the other. Choosing the results from 21-input model, the UCC-FA decreases from 2.7% to 1.7% via optimizing some of the operational parameters, which is a reasonable achievement for the boiler combustion.

  14. Effect of fluidization number on the combustion of simulated municipal solid waste in a fluidized bed

    International Nuclear Information System (INIS)

    Anwar Johari; Mutahharah, M.M.; Abdul, A.; Salema, A.; Kalantarifard, A.; Rozainee, M.

    2010-01-01

    The effect of fluidization number on the combustion of simulated municipal solid was in a fluidized bed was investigated. Simulated municipal solid waste was used a sample and it was formulated from major waste composition found in Malaysia which comprised of food waste, paper, plastic and vegetable waste. Proximate and ultimate analyses of the simulated were conducted and results showed its composition was similar to the actual Malaysian municipal solid waste composition. Combustion study was carried out in a rectangular fluidized bed with sand of mean particle size of 0.34 mm as a fluidising medium. The range of fluidization numbers investigated was 3 to 11 U mf . The combustion was carried out at stoichiometric condition (Air Factor = 1). Results showed that the best fluidization number was in the range of 5 to 7 U mf with 5 U mf being the most optimum in which the bed temperature was sustained in a much longer period. (author)

  15. Improving lithium-ion battery performances by adding fly ash from coal combustion on cathode film

    Energy Technology Data Exchange (ETDEWEB)

    Dyartanti, Endah Retno; Jumari, Arif, E-mail: arifjumari@yahoo.com; Nur, Adrian; Purwanto, Agus [Research Group of Battery & Advanced Material, Department of Chemical Engineering, Sebelas Maret University, Jl. Ir. Sutami 36 A Kentingan, Surakarta Indonesia 57126 (Indonesia)

    2016-02-08

    A lithium battery is composed of anode, cathode and a separator. The performance of lithium battery is also influenced by the conductive material of cathode film. In this research, the use of fly ash from coal combustion as conductive enhancer for increasing the performances of lithium battery was investigated. Lithium iron phosphate (LiFePO{sub 4}) was used as the active material of cathode. The dry fly ash passed through 200 mesh screen, LiFePO{sub 4} and acethylene black (AB), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed to form slurry. The slurry was then coated, dried and hot pressed to obtain the cathode film. The ratio of fly ash and AB were varied at the values of 1%, 2%, 3%, 4% and 5% while the other components were at constant. The anode film was casted with certain thickness and composition. The performance of battery lithium was examined by Eight Channel Battery Analyzer, the composition of the cathode film was examined by XRD (X-Ray Diffraction), and the structure and morphology of the anode film was analyzed by SEM (Scanning Electron Microscope). The composition, structure and morphology of cathode film was only different when fly ash added was 4% of AB or more. The addition of 2% of AB on cathode film gave the best performance of 81.712 mAh/g on charging and 79.412 mAh/g on discharging.

  16. Ash-forming elements in four Scandinavian wood species part 3: Combustion of five spruce samples

    Energy Technology Data Exchange (ETDEWEB)

    Werkelin, Johan; Lindberg, Daniel; Skrifvars, Bengt-Johan; Hupa, Mikko [Aabo Akademi Process Chemistry Centre, Piispankatu 8, FI-20500 Turku (Finland); Bostroem, Dan [Energy Technology and Thermal Process Chemistry, Umeaa University, SE-901 87 Umeaa (Sweden)

    2011-01-15

    Forest residue is the remaining fraction after the outtake of timber, which comprises the tree tops and branches. It may as fuel cause damage to the combustion device through ash slagging and fouling. The objective of this work was to model the ash composition from well-specified samples of a spruce tree: wood, bark, twigs, needles, and shoots. Their ash at 1000 C was modelled using global chemical equilibrium calculations, and laboratory-made ash of the five samples was analyzed by XRD and SEM-EDXA. According to the results, the risk of slagging arises from the spruce foliage: molten alkali silicates from spruce needles and probably molten alkali phosphates from spruce shoots may cause problems in the furnace. Fouling caused by condensing alkali vapours can be produced by all five samples. The amount of alkali vapours in the flue gas was in the same order of magnitude for all five samples, in spite of large differences in their original alkali contents. (author)

  17. Success of lime additives for controlling SO2 releases from fluidized bed combustion units

    International Nuclear Information System (INIS)

    Muezzinoglu, A.; Bayram, A.; Odabasi, M.

    1995-01-01

    Purpose of this work was to study the desulfurization efficiencies of dry additives on the fluidized bed reactors fired with low quality lignites. In these tests selected initial SO 2 levels were in the order of 1000 ppm or less in the flue gases. Lime addition for desulfurization may either be made by mixing with the fuel or by injection into the combustion reactor. In fluidized bed combustion systems both methods are physically possible. In the fluidized combustion systems a third method of addition is also possible this, is by mixing dry additives with fluidizer sand. In this third method additives create a fluidizer effect as well as reacting with the sulfur oxides being formed during the combustion of fuel

  18. Reduced ash-related operational problems by co-combustion peat and agricultural fuels; Minskade askrelaterade driftsproblem genom inblandning av torv i aakerbraenslen

    Energy Technology Data Exchange (ETDEWEB)

    Oehman, Marcus; Bostroem, Dan; Skoglund, Nils; Grimm, Alejandro; Boman, Christoffer; Kofod-Hansen, Marie

    2010-06-15

    The objectives of the project were: To determine the admixing levels for different peat classes to various energy crops (straw, Salix and Reed canary grass) that are required to reach positive effects regarding slagging, deposit formation/(high temperature corrosion) and bed agglomeration; and, To demonstrate the possibilities to reduce the occurrence of ash related operational problems in combustion of energy crops upon admixing peat. Operational experiences and research of effects of co-firing peat and energy crops are scarce. Some previous tests in bench scale indicated though, on a strong reduction of the agglomeration tendency and lowering of the agglomeration temperature for straw and Salix at a peat admixing level corresponding to 15 - 20 weight% (on DS basis). A reduction in the amount of emitted fine particles was also observed in these experiments. However, care must be taken in the choice of peat. Some Carex dominated peats with high Si contents may cause problems with slagging. Another conclusion from the mentioned bench scale tests was that peats with relative high Ca/Si ratios should be selected to minimize the risk of slagging and bed agglomeration. Thermochemical modelling was performed to determine the effects of peat admixture, on slagging-, deposit formation- (corrosion)- and bed agglomeration tendencies during combustion of straw, willow and reed canary grass with high and low ash content. These results and previously conducted bench scale experiments were used as a basis for determining combinations of fuel and peat admixtures for the demonstration experiments. The calculations were performed with admixing levels of 0-, 5-, 15, 25-, and 40 weight% (on DS basis) of four peat samples to the investigated four crop fuels. The used peat samples were typical carex-containing Swedish peat with differences in e.g. silicon-, calcium- and sulfur contents. A number of the model calculations were qualitatively validated against previously conducted

  19. Environmental, physical and structural characterisation of geopolymer matrixes synthesised from coal (co-)combustion fly ashes

    International Nuclear Information System (INIS)

    Alvarez-Ayuso, E.; Querol, X.; Plana, F.; Alastuey, A.; Moreno, N.; Izquierdo, M.; Font, O.; Moreno, T.; Diez, S.; Vazquez, E.; Barra, M.

    2008-01-01

    The synthesis of geopolymer matrixes from coal (co-)combustion fly ashes as the sole source of silica and alumina has been studied in order to assess both their capacity to immobilise the potentially toxic elements contained in these coal (co-)combustion by-products and their suitability to be used as cement replacements. The geopolymerisation process has been performed using (5, 8 and 12 M) NaOH solutions as activation media and different curing time (6-48 h) and temperature (40-80 o C) conditions. Synthesised geopolymers have been characterised with regard to their leaching behaviour, following the DIN 38414-S4 [DIN 38414-S4, Determination of leachability by water (S4), group S: sludge and sediments. German standard methods for the examination of water, waste water and sludge. Institut fuer Normung, Berlin, 1984] and NEN 7375 [NEN 7375, Leaching characteristics of moulded or monolithic building and waste materials. Determination of leaching of inorganic components with the diffusion test. Netherlands Normalisation Institute, Delft, 2004] procedures, and to their structural stability by means of compressive strength measurements. In addition, geopolymer mineralogy, morphology and structure have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. It was found that synthesised geopolymer matrixes were only effective in the chemical immobilisation of a number of elements of environmental concern contained in fly ashes, reducing (especially for Ba), or maintaining their leachable contents after the geopolymerisation process, but not for those elements present as oxyanions. Physical entrapment does not seem either to contribute in an important way, in general, to the immobilisation of oxyanions. The structural stability of synthesised geopolymers was mainly dependent on the glass content of fly ashes, attaining at the optimal activation conditions (12 M NaOH, 48 h, 80 o C

  20. Co-combustion of waste with coal in a circulating fluidised bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, I.; Boavida, D.; Abelha, P.; Lopes, H.; Cabrita, I. [DEECA-INETI, Lisboa (Portugal)

    2002-07-01

    The results of a study of cocombustion of waste with coal is described. Various wastes (biomass, sludge, and refuse derived fuel) were burned with coal in a circulating fluidised bed combustor. Conditions that prevent segregated combustion, reduce production of nitrogen oxides, and attain high combustion efficiency were studied. The effects of variations in air staging in the riser, mixing of air with volatiles, coal/biomass ratio, methods of feeding biomass, and temperature are described. 5 refs., 3 figs., 5 tabs.

  1. Effect of secondary air injection on the combustion efficiency of sawdust in a fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    K. V. N. Srinivasa Rao

    2008-03-01

    Full Text Available Agricultural wastes like bagasse, paddy husks, sawdust and groundnut shells can be effectively used as fuels for fluidized bed combustion; otherwise these biomass fuels are difficult to handle due to high moisture and fines content. In the present work the possibility of using sawdust in the fluidized bed combustor, related combustion efficiencies and problems encountered in the combustion process are discussed. The temperature profiles for sawdust with an increase in fluidizing velocity along the vertical height above the distributor plate indicate that considerable burning of fuel particles is taking place in the freeboard zone rather than complete burning within the bed. Therefore, an enlarged disengagement section is provided to improve the combustion of fines. The temperature profiles along the bed height are observed at different feed rates. The feed rate of sawdust corresponding to the maximum possible temperature was observed to be 10.2 kg/h. It is observed that 50-60% excess air is optimal for reducing carbon loss during the burning of sawdust. The maximum possible combustion efficiency with sawdust is 99.2% and is observed with 65% excess air.

  2. Effects of setting new source performance standards for fluidized-bed combustion systems

    Energy Technology Data Exchange (ETDEWEB)

    1978-02-01

    This study was undertaken for the US Environmental Protection Agency to examine the potential consequences of revisions in New Source Performance Standards (NSPS) on fluidized-bed combustor-based steam electric generators of greater than 250,000,000 Btu. A study of the appropriateness and differential effects of alternate regulatory approaches to the standards-setting process was made. Problems dealing with an emerging technology such as fluidized-bed combustion were emphasized. Finally, an examination was made of the potential benefits of fluidized-bed combustion (FBC) systems relative to conventional coal-fired systems equipped with scrubbers. Information is included on the relative advantages and disadvantages of utility-sized fluidized-bed combustors, the technical consequences of NSPS alternatives, policy implications concerning NSPS for steam-electric generators, and cost models for atmospheric and pressurized FBC systems. (LCL)

  3. Ash behavior in the combustion of phosphorus rich biofuels - literature survey and experimental studies

    DEFF Research Database (Denmark)

    Wu, Hao; Castro, Maria; Jensen, Peter Arendt

    Utilization of biofuels such as grain, bran and rapeseed meal in energy production is considered to have ecological and economical benefits. These seed-originated biofuels usually contain significantly higher phosphorus contents than other biofuels, which may induce some ash related operation...... problems. In this report, the behaviors of inorganic species during the combustion of phosphorus rich biofuels are studied through literature review and experiments. It is found that the majority of P, Mg and K in these biofuels would be present as phytic acid/phytate or other inositol phosphate. During...

  4. Pyrite thermochemistry, ash agglomeration, and char fragmentation during pulverized coal combustion. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Akan-Etuk, A.; Diaz, R.; Niksa, S.

    1991-10-01

    The objective of the present work is to introduce an experimental program that will eventually lead to time-resolved iron ash composition over the technological operating domain. The preceding literature survey suggests two important stipulations on any such experimental program. The first stipulation is that good control must be established over the operating conditions, to accurately quantify their effects. The other is that data must be obtained rapidly, to thoroughly cover the important operating domain. This work presents a series of studies that has characterized the desulfurization of pyrite during the early stages of combustion. An experimental system was established and used to monitor the effects of oxygen, temperature, and residence time on the evolution of condensed phase products of the combustion of pure pyrite. (VC)

  5. Pyrite thermochemistry, ash agglomeration, and char fragmentation during pulverized coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Akan-Etuk, A.; Diaz, R.; Niksa, S.

    1991-10-01

    The objective of the present work is to introduce an experimental program that will eventually lead to time-resolved iron ash composition over the technological operating domain. The preceding literature survey suggests two important stipulations on any such experimental program. The first stipulation is that good control must be established over the operating conditions, to accurately quantify their effects. The other is that data must be obtained rapidly, to thoroughly cover the important operating domain. This work presents a series of studies that has characterized the desulfurization of pyrite during the early stages of combustion. An experimental system was established and used to monitor the effects of oxygen, temperature, and residence time on the evolution of condensed phase products of the combustion of pure pyrite. (VC)

  6. Improvement in equipment for initiating combustion of bituminous beds

    Energy Technology Data Exchange (ETDEWEB)

    Kleyev, A M; Galimov, R R; Smerkovich, Y S

    1981-01-01

    An experimental sample of a unit is developed based on the logging lifter PK-2 which was tested with initiation of intrabed combustion at the Sugushlinskiy field (viscosity of bitumen over 10/sup 3/ Pa.s) and Mordovo-Karmal'skiy field (viscosity of bitumen up to 3 Pa.s). Technical characteristics and operating principles of the unit are presented.

  7. Experiment and modeling of low-concentration methane catalytic combustion in a fluidized bed reactor

    International Nuclear Information System (INIS)

    Yang, Zhongqing; Yang, Peng; Zhang, Li; Guo, Mingnv; Ran, Jingyu

    2016-01-01

    Highlights: • The catalytic combustion of 0.15~3 vol. % low concentration methane in a fluidized bed was studied. • A mathematical model was proposed on the basis of gas–solid flow theory. • A comparative analysis of the established model with plug flow, mixed flow and K-L models was carried out. • The axial methane profile along fluidized bed was predicted by using the mathematical model. • The bed temperature has greater impact on methane conversion than fluidized velocity. - Abstract: This study undertakes a theoretical analysis and an experimental investigation into the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed reactor using 0.5 wt.% Pd/Al_2O_3 as catalytic particles. A mathematical model is established based on gas–solid flow theory and is used to study the effects of bed temperature and fluidized velocity on methane catalytic combustion, and predict the dimensionless methane concentration axial profile in reactor. It is shown that methane conversion increases with bed temperature, but decreases with increasing fluidized velocity. These theoretical results are found to correlate well with the experimental measurement, with a deviation within 5%. A comparative analysis of the developed model with plug flow, mixed flow and K-L models is also carried out, and this further verifies that the established model better reflects the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed. Using this reaction model, it was found that the difference in methane conversion between dense and freeboard zones gradually increases with bed temperature; the dense zone reaction levels off at 650 °C, thereby minimizing the difference between the dense and freeboard regions to around 15%. With an increase in bed temperature, the dimensionless methane concentration in the dense zone decreases exponentially, while in the splash zone, it varies from an exponential decay to a slow

  8. SPECIFIC FEATURES OF THE OXYFUEL COMBUSTION CONDITIONS IN A BUBBLING FLUIDIZED BED

    Directory of Open Access Journals (Sweden)

    Pavel Skopec

    2016-08-01

    Full Text Available Oxyfuel combustion is a promising approach for capturing CO2 from power plants. This technology produces a flue gas with a high concentration of CO2. Our paper presents a verification of the oxyfuel combustion conditions in a bubbling fluidized bed combustor. It presents a theoretical analysis of oxyfuel combustion and makes a comparison with combustion using air. It is important to establish a proper methodology for stoichiometric calculations and for computing the basic characteristic fluidization properties. The methodology presented here has been developed for general purposes, and can be applied to calculations for combustion with air and with oxygen-enriched air, and also for full oxyfuel conditions. With this methodology, we can include any water vapour condensation during recirculation of the flue gas when dry flue gas recirculation is used. The paper contains calculations for a lignite coal, which is taken as a reference fuel for future research and for the experiments.

  9. Effect of limestone addition on chlorine compound emissions in grate and fluidized-bed combustion of recovered fuels

    International Nuclear Information System (INIS)

    Vesterinen, R.; Ruuskanen, J.

    2000-01-01

    The aim was to verify the positive results of laboratory experiments concerning the reducing effect of limestone addition on emissions of organic chlorine compounds and acidifying compounds (HCl, HF, SO 2 ) in grate and fluidized-bed combustion of recovered fuels in commercial boilers. The final aim is to develop a cheap and practical way of reducing emissions of organic chlorine compounds in co-combustion of recovered fuels. Pellets produced from the mixture of recovered fuel and limestone is a product ready for use in plants without any need of additional employees or equipment for limestone feed. Pellets produced by Ewapower Oy are used as recovered fuel and Gotland limestone of Partek Nordkalk Oyj Abp as limestone. Ewapower Oy produces pellets by feeding a certain proportion of limestone among recovered fuel at the production stage. Experiments are carried out in one grate-combustion plant and in one or two fluidized-bed plants. The first experiments were carried out in a 3 MWth BioGrate boiler at the new heating station of Pielavesi municipality in autumn 1999. The flue gases are cleaned with a cyclone (FinCleaner). The main fuel was a mixture of bark and sawdust (3:1) from a sawmill. Ewapower pellets with an addition of Gotland limestone were used as recovered fuel. The experiments were carried out at about 2 MW boiler output. Temperatures of the furnace and flue gas, pressure and fuel gas composition were measured continuously. For determining the composition of gas, O 2 , CO, CO 2 , hydrocarbons and N 2 O(FTIR), NO x and SO 2 were measured continuously. HCl, heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF), polyaromatic hydrocarbons (PAH), chlorobenzenes, chlorophenols and PCB were measured as one-shot determinations. Fuel and ash samples were also collected during the experiments. The organic compounds were analyzed by the Department of Environmental Science of the University of Kuopio, which is

  10. Combustion of agro-waste with coal in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Atimtay, Aysel T. [Middle East Technical University, Department of Environmental Engineering, Ankara (Turkey)

    2010-02-15

    In this study, a review of the studies done on the co-combustion of some agro-waste in a bubbling fluidized bed combustor (BFBC) having an inside diameter of 102 mm and a height of 900 mm is given. The agro-waste used to investigate the co-combustion characteristics were peach and apricot stones produced as a waste from the fruit juice industry, and olive cake produced as a waste from the olive oil industry. These are typical wastes for a Mediterranean country. A lignite coal was used for co-combustion. On-line concentrations of O{sub 2}, CO, CO{sub 2}, SO{sub 2}, NO{sub x} and total hydrocarbons (C{sub m} H{sub n}) were measured in the flue gas during combustion experiments. Variations of emissions of various pollutants were studied by changing the operating parameters (excess air ratio, fluidization velocity and fuel feed rate). Temperature distribution along the bed was measured with thermocouples. Emissions were also monitored from the exhaust. Various combinations of coal and biomass mixtures were tested. During the combustion tests, it was observed that the volatile matter from the biomass quickly volatilizes and mostly burns in the freeboard. The temperature profiles along the bed and the freeboard also confirmed this phenomenon. It was found that as the volatile matter of the biomass increases, combustion takes place more in the freeboard region. Better combustion conditions occur at higher excess air ratios. The results showed that co-combustion with these three proposed biomasses lowers the SO{sub 2} and NO{sub x} emissions considerably. CO and hydrocarbon emissions are lower at the higher excess air ratios. (orig.)

  11. Wood Combustion Behaviour in a Fixed Bed Combustor

    Science.gov (United States)

    Tokit, Ernie Mat; Aziz, Azhar Abdul; Ghazali, Normah Mohd

    2010-06-01

    Waste wood is used as feedstock for Universiti Teknologi Malaysia's newly-developed two-stage incinerator system. The research goals are to optimize the operation of the thermal system to the primary chamber, to improve its combustion efficiency and to minimize its pollutants formation. The combustion process is evaluated with the variation of fuel's moisture content. For optimum operating condition, where the gasification efficiency is 95.53%, the moisture content of the fuel is best set at 17%; giving outlet operating temperature of 550°C and exhaust gas concentrations with 1213 ppm of CO, 6% of CO2 and 14% of O2 respectively. In line to the experimental work, a computational fluid dynamics software, Fluent is used to simulate the performance of the primary chamber. Here the predicted optimum gasification efficiency stands at 95.49% with CO, CO2 and O2 concentrations as 1301 ppm, 6.5% and 13.5% respectively.

  12. Obtaining zeolites from slags and ashes from a waste combustion plant in an autoclave process

    Directory of Open Access Journals (Sweden)

    Grela Agnieszka

    2017-01-01

    Full Text Available Waste combustion is associated with the generation of post-processing solid products – waste such as slag and ash. One of the promising technologies in waste management and processing is the synthesis of zeolites and other materials exhibiting sorption properties. The aim of this study was to characterise and assess the physicochemical properties of the waste and the products synthesised from it. This paper presents the possibility of synthesis zeolites from the slag and ash from two waste combustion plants. The investigated waste is classified as hazardous waste and denoted by the EWC code 190111*. The paper presents the results of physicochemical studies of these materials. As a result of synthesis in an autoclave at 140°C with the use of 2 M NaOH, and other compounds, such zeolite forms as chabazite and sodalite were obtained. Textural studies and ion-exchange capacity investigations carried out allowed characterisation of the sorption properties of the materials. It was found that the materials obtained are characterised by the BET specific surface areas of 25.45 m2/g and 16.79 m2/g.

  13. a novel interconnected fluidised bed for the combined flash pyrolysis of biomass and combustion of char

    NARCIS (Netherlands)

    Janse, A.M.C.; Janse, Arthur M.C.; Biesheuvel, P.M.; Biesheuvel, Pieter Maarten; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1999-01-01

    A novel system of two adjacent fluidised beds operating in different gas atmospheres and exchanging solids was developed for the combined flash pyrolysis of biomass and combustion of the produced char. Fluidised sand particles (200 μm < dp < 400 μm) are transported from the pyrolysis reactor to the

  14. A novel interconnected fluidised bed for the combined flash pyrolysis of biomass and combustion of char.

    NARCIS (Netherlands)

    Janse, Arthur M.C.; Janse, A.M.C.; Biesheuvel, P.M.; Biesheuvel, Pieter Maarten; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    2000-01-01

    A novel system of two adjacent fluidised beds operating in different gas atmospheres and exchanging solids was developed for the combined flash pyrolysis of biomass and combustion of the produced char. Fluidised sand particles (200 μm < dp < 400 μm) are transported from the pyrolysis reactor to the

  15. The combustion of low calorific value fuels (oil shale) by using fluidized bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Azzam, S M

    1994-12-31

    The present work reports an experimental data for combustion of oil-shale in a fluidized bed combustor. The experimental set up was designed for the combustion of low calorific value fuel such as oil-shale to facilitate the variation of many parameters over a wide operating range. A cold run was firstly conducted to study the fluidization parameters. Fluidization experiment were made with different sized quartiz particles. Minimum fluidization velocities and other fluidization characteristics were determined at room temperature. Secondary a hot run was started, first studying the combustion of `LPG` in a fluidized bed as a starting process, then studying the combustion if oil-shale with different flow rates. The experimetal results are promising and give rise to hopes that this valuable deposit can be used as a fuel source and can be burned sucessfully in a fluidized bed combustor. This study had prooved that utilization of oil-shale a fuel source is no more a complicated technical problem, this opens the way for power generation using fluidized bed combustors. (author). 17 refs., 32 figs., 3 tabs.

  16. The combustion of low calorific value fuels (oil shale) by using fluidized bed combustor

    International Nuclear Information System (INIS)

    Azzam, S.M.

    1993-01-01

    The present work reports an experimental data for combustion of oil-shale in a fluidized bed combustor. The experimental set up was designed for the combustion of low calorific value fuel such as oil-shale to facilitate the variation of many parameters over a wide operating range. A cold run was firstly conducted to study the fluidization parameters. Fluidization experiment were made with different sized quartiz particles. Minimum fluidization velocities and other fluidization characteristics were determined at room temperature. Secondary a hot run was started, first studying the combustion of 'LPG' in a fluidized bed as a starting process, then studying the combustion if oil-shale with different flow rates. The experimetal results are promising and give rise to hopes that this valuable deposit can be used as a fuel source and can be burned sucessfully in a fluidized bed combustor. This study had prooved that utilization of oil-shale a fuel source is no more a complicated technical problem, this opens the way for power generation using fluidized bed combustors. (author). 17 refs., 32 figs., 3 tabs

  17. Behaviour of Inorganic Constituents of Municipal Sewage Sludge during Fluidized-Bed Combustion.

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Pohořelý, Michael; Trnka, Otakar

    2007-01-01

    Roč. 61, 3 (2007) , s. 181-185 ISSN 0366-6352 R&D Projects: GA AV ČR(CZ) IAA4072201 Institutional research plan: CEZ:AV0Z40720504 Keywords : sewage sludge * heavy metals * fluidized-bed combustion Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.367, year: 2007

  18. Combustion of Liquid Bio-Fuels in an Internal Circulating Fluidized Bed

    Czech Academy of Sciences Publication Activity Database

    Miccio, F.; Kalisz, S.; Baxter, D.; Svoboda, Karel

    2008-01-01

    Roč. 143, 1-3 (2008), s. 172-179 ISSN 1385-8947 Institutional research plan: CEZ:AV0Z40720504 Keywords : internal circulating fluidized bed * liquid fuel * combustion Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.813, year: 2008

  19. Post-combustion CO2 capture with activated carbons using fixed bed adsorption

    Science.gov (United States)

    Al Mesfer, Mohammed K.; Danish, Mohd; Fahmy, Yasser M.; Rashid, Md. Mamoon

    2018-03-01

    In the current work, the capturing of carbon dioxide from flue gases of post combustion emission using fixed bed adsorption has been carried out. Two grades of commercial activated carbon (sorbent-1 and sorbent-2) were used as adsorbent. Feed consisting of CO2 and N2 mixture was used for carrying out the adsorption. The influence of bed temperature, feed rate, equilibrium partial pressure and initial % CO2 in feed were considered for analyzing adsorption-desorption process. It was found that the total adsorption-desorption cycle time decreases with increased column temperature and feed rates. The time required to achieve the condition of bed saturation decreases with increased bed temperature and feed rates. The amount of CO2 adsorbed/Kg of the adsorbent declines with increased bed temperature with in studied range for sorbent-1 and sorbent-2. It was suggested that the adsorption capacity of the both the sorbents increases with increased partial pressure of the gas.

  20. Computational fluid dynamics simulation for chemical looping combustion of coal in a dual circulation fluidized bed

    International Nuclear Information System (INIS)

    Su, Mingze; Zhao, Haibo; Ma, Jinchen

    2015-01-01

    Highlights: • CFD simulation of a 5 kW_t_h CLC reactor of coal was conducted. • Gas leakage, flow pattern and combustion efficiency of the reactor was analyzed. • Optimal condition was achieved based on operation characteristics understanding. - Abstract: A dual circulation fluidized bed system is widely accepted for chemical looping combustion (CLC) for enriching CO_2 from the utilization of fossil fuels. Due to the limitations of the measurement, the details of multiphase reactive flows in the interconnected fluidized bed reactors are difficult to obtain. Computational Fluid Dynamics (CFD) simulation provides a promising method to understand the hydrodynamics, chemical reaction, and heat and mass transfers in CLC reactors, which are very important for the rational design, optimal operation, and scaling-up of the CLC system. In this work, a 5 kW_t_h coal-fired CLC dual circulation fluidized bed system, which was developed by our research group, was first simulated for understanding gas leakage, flow pattern and combustion efficiency. The simulation results achieved good agreement with the experimental measurements, which validates the simulation model. Subsequently, to improve the combustion efficiency, a new operation condition was simulated by increasing the reactor temperature and decreasing the coal feeding. An improvement in the combustion efficiency was attained, and the simulation results for the new operation condition were also validated by the experimental measurements in the same CLC combustor. All of the above processes demonstrated the validity and usefulness of the simulation results to improve the CLC reactor operation.

  1. Method for the combustion of a gas, in fixed bed, with an oxidized solid and associated installation

    OpenAIRE

    Abanades García, Juan Carlos; Fernández García, José Ramón

    2014-01-01

    [EN] The present invention pertains to the field of the generation of energy from combustible gases, incorporating the capture of carbon dioxide for use or permanent storage and, specifically relates to cyclical methods of gas combustion with oxidized solids (chemical looping processes), in fixed bed, for solving the problem of controlling temperature in the combustion of gaseous fuels in fixed beds of metal oxides operating at high pressures, and also the associated installation.

  2. Contribution to the combustion and emission of nitrogen oxides of Kosovo and Kolubara coals in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Radovanovic, M.; Savic, R.

    1996-12-31

    In this paper, the results of combustion of different sizes of domestic lignites Kosovo and Kolubara are presented. Investigation has been carried on a laboratory experimental facility for combustion in fluidized bed, power 1 kW. Specified amount of fuel is put into fluidized bed and temperature and concentration of combustion products (O{sub 2}, CO{sub 2}, CO, NO, NO{sub s} and SO{sub 2}) are recorded and produced. The emission of nitrogen oxides is specially treated in this paper. Also, the ignition delay of volatile matter, combustion of volatiles and total time of combustion are found. 25 refs., 9 figs., 4 tabs.

  3. Thermal stability in a newly designed columnar-conical fluidized bed for combustion of rice husk

    Energy Technology Data Exchange (ETDEWEB)

    Rozainee, M.; Salema, A.A.; Ngo, S.P.; Chye, G.B. [Malaysian Technological Univ., Johor Bahru (Malaysia). Dept. of Chemical Engineering

    2006-07-01

    The effects of fluidizing and liquid propane gas (LPG) flow rates on thermal stability of a fluidized bed were examined. The aim of the study was to hybridize a columnar and conical fluidized bed (CCFB) in order to encourage the combustion of low-calorific fuels such as rice husks. Experiments were conducted to examine the thermal stability of the CCFB. Premixed primary air and liquid propane gas (LPG) was fed into the bed in order to verify its thermal stability. Temperature profiles of the combustor and bed were measured. The impact of the fluidizing velocity and LPG flow rate on the temperature profile was examined in order to analyze the influence of the fluidizing velocity and LPG rate on combustion rates. Results of the study showed that the combustion of the CCFB was sustained at a fluidizing velocity of 1.5 U{sub mf} and at an LPG flow rate of 8 liters per minute. Results of the study showed that fluidizing velocity played an important role on the thermal stability of the bed. It was concluded that the thermal stability of the combustor is sufficient for the CCFB. 13 refs., 2 tabs., 5 figs.

  4. CO-COMBUSTION OF REFUSE DERIVED FUEL WITH COAL IN A FLUIDISED BED COMBUSTOR

    Directory of Open Access Journals (Sweden)

    W. A. WAN AB KARIM GHANI

    2009-03-01

    Full Text Available Power generation from biomass is an attractive technology which utilizes municipal solid waste-based refused derived fuel. In order to explain the behavior of biomass-fired fluidized bed incinerator, biomass sources from refuse derived fuel was co-fired with coal in a 0.15 m diameter and 2.3 m high fluidized bed combustor. The combustion efficiency and carbon monoxide emissions were studied and compared with those from pure coal combustion. This study proved that the blending effect had increased the carbon combustion efficiency up to 12% as compared to single MSW-based RDF. Carbon monoxide levels fluctuated between 200-1600 ppm were observed when coal is added. It is evident from this research that efficient co-firing of biomass with coal can be achieved with minimum modification of existing coal-fired boilers.

  5. Proceedings of the sixth international conference on fluidized bed combustion. Volume II. Technical sessions

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-08-01

    The Sixth International Conference on Fluidized Bed Combustion was held April 9-11, 1980, at the Atlanta Hilton, Atlanta, Georgia. It was sponsored by the US Department of Energy, the Electric Power Research Institute, the US Environmental Protection Agency, and the Tennessee Valley Authority. The papers covered recent developments in atmospheric and pressurized fluidized-bed combustion, especially the design, operation and control of pilot and demonstration plants. The cleanup of combustion products and the erosion, corrosion and fouling of gas turbines was emphasized also. Fifty-five papers from Volume 2 of the proceedings have been entered individually into EDB and ERA; five papers had been entered previously from other sources. (LTN)

  6. Simultaneous determination of devolatilization and char burnout times during fluidized bed combustion of coal

    International Nuclear Information System (INIS)

    Christofiedes, N.; Brown, R.C.

    1992-01-01

    In this paper, the authors investigate a method for simultaneous determination of devolatilization and char burnout times based on the analysis of CO 2 emissions from a fluidized bed combustor. The technique is non-intrusive and can be performed under realistic combustion conditions. The authors' method involves batching single-size coal samples in a fluidized bed combustor that is heated with propane gas or other fuel. Carbon dioxide profiles versus time for the batch tests are analyzed with a linear model to obtain characteristic time constants for coal devolatilization and char combustion which can be related to total devolatilization time and burnout time for a coal sample. The authors' approach does not require special sample preparation, can be performed in actual combustion equipment and employs standard boiler instrumentation

  7. Prevention of trace and major element leaching from coal combustion products by hydrothermally-treated coal ash

    Energy Technology Data Exchange (ETDEWEB)

    Adnadjevic, B.; Popovic, A.; Mikasinovic, B. [University of Belgrade, Belgrade (Serbia). Dept. of Chemistry

    2009-07-01

    The most important structural components of coal ash obtained by coal combustion in 'Nikola Tesla A' power plant located near Belgrade (Serbia) are amorphous alumosilicate, alpha-quartz, and mullite. The phase composition of coal ash can be altered to obtain zeolite type NaA that crystallizes in a narrow crystallization field (SiO{sub 2}/Al{sub 2}O{sub 3}; Na{sub 2}O/SiO{sub 2}; H{sub 2}O/Na{sub 2}O ratios). Basic properties (crystallization degree, chemical composition, the energy of activation) of obtained zeolites were established. Coal ash extracts treated with obtained ion-exchange material showed that zeolites obtained from coal ash were able to reduce the amounts of iron, chromium, nickel, zinc, copper, lead, and manganese in ash extracts, thus proving its potential in preventing pollution from dump effluent waters.

  8. Mercury and toxic metals in ash from combustion and incineration processes; Mercurio y metales toxicos en cenizas provenientes de procesos de combustion e incineracion

    Energy Technology Data Exchange (ETDEWEB)

    Mugica, V.; Amador, M.A.; Torres, M.; Figueroa, J. de J. [Universidad Autonomo-Metropolitana-Azcapotzalco, Reynosa (Mexico)

    2003-07-01

    In Mexico, most of the ashes from combustion and incineration process were not appropriately disposed, they are either left on industrial yards and cliffs or thrown away in open spaces and then carried by the wind to places where they can harm population, affect aquatic environment or soils. For prevention and control, the knowledge on the concentration of trace elements in waste ashes is necessary. In this study, several oxidation methods for digestion of ashes followed by inductively coupled plasma emission spectrometry were evaluated. Hg, Cd, Cr, Cu, Ni, Pb and V were determined in ashes from coal and fuel oil combustion, as well as in ashes from the incineration of municipal, water treatment sludge, and medical wastes. Results showed important concentrations of different trace elements in the ashes. This suggests that adequate disposal of these wastes should be mandatory. On the other hand, concentration of trace elements in the leachates indicated that these wastes are not toxic and they could be disposed in sanitary landfill. 23 refs.

  9. ESTABLISHMENT OF AN ENVIRONMENTAL CONTROL TECHNOLOGY LABORATORY WITH A CIRCULATING FLUIDIZED-BED COMBUSTION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Wei-Ping Pan; Andy Wu; John T. Riley

    2004-10-30

    This report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period July 1, 2004 through September 30, 2004. The following tasks have been completed. First, renovation of the new Combustion Laboratory and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building have started. Second, the design if the component parts of the CFBC system have been reviewed and finalized so that the drawings may be released to the manufacturers during the next quarter. Third, the experiments for solid waste (chicken litter) incineration have been conducted using a Thermogravimetric Analyzer (TGA). This is in preparation for testing in the simulated fluidized-bed combustor. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter has been outlined in this report.

  10. Lewis pressurized, fluidized-bed combustion program. Data and calculated results

    Science.gov (United States)

    Rollbuhler, R. J.

    1982-03-01

    A 200 kilowatt (thermal), pressurized, fluidized bed (PFB) reactor and research test facility were designed, constructed, and operated. The facility was established to assess and evaluate the effect of PFB hot gas effluent on aircraft turbine engine materials that may have applications in stationary powerplant turbogenerators. The facility was intended for research and development work and was designed to operate over a wide range of conditions. These conditions included the type and rate of consumption of fuel (e.g., coal) and sulfur reacting sorbent material: the ratio of feed fuel to sorbent material; the ratio of feed fuel to combustion airflow; the depth of the fluidized reaction bed; the temperature and pressure in the reaction bed; and the type of test unit that was exposed to the combustion exhaust gases.

  11. Fluidized-bed combustion of refuse-derived fuels; Verbrennung von Ersatzbrennstoff in der Wirbelschicht

    Energy Technology Data Exchange (ETDEWEB)

    Steinbrecht, D.; Wolff, H.-J.; Matzmohr, R. [Universitaet Rostock (Germany). Institut fuer Energie und Umwelttechnik

    2004-07-01

    The experiments in the SWSF DN 400 test facility were to prove that combustion in a stationary, bubbling fluidized bed is an economically and ecologically feasible technology for treating the high-calorific fractions of waste materials conditioned in a mechanical and biological treatment system. This comprised the following tasks: Proof of the long-term suitability and availability of the selected fluidized-bed process; Reduction or prevention of emissions by primary, in-process measures in accordance with the specifications of the German Nuisance Control Ordinance (17. BImSchV); No secondary (additive) off-gas purification stages apart from a mechanical dedusting stage. The combustion off-gas of the fluidized-bed combustor were used for heat and power generation in a steam generator connected in series with the furnace. (orig.)

  12. Investigation of additives for preventing ash fouling and sintering during barley straw combustion

    International Nuclear Information System (INIS)

    Wang, Liang; Skreiberg, Øyvind; Becidan, Michael

    2014-01-01

    Formation of potassium chloride reduces ash sintering temperature and causes fouling deposits in biomass combustion applications. In the present work, the capacity of two mineral additives zeolite 24A and kaolin to capture KCl were investigated. A series of thermogravimetric experiments were carried out to measure fractions of KCl retained in the two additives as function of reaction temperature and heating time. The residues from additive-KCl mixtures after heating treatment were analyzed by X-ray diffractometry (XRD). When heated at 900 °C for 1 h, the overall KCl capturing efficiencies of the two additives were 60% and 45% for zeolite 24A and kaolin respectively, which slightly decreased to 50% and 43% as the heating time increased to 12 h. At 1000 °C, the fractions of KCl captured by zeolite 24A and kaolin significantly decreased from 50% and 40% to 26% and 17%, as the KCl-additive mixtures were heated for 1 and 12 h, respectively. The decrease in of the overall KCl capturing efficiencies is mainly attributed to reduction of surface areas and chemically active compounds of the two additives with increasing temperature and heating time. The XRD analysis results showed that both zeolite 24A and kaolin can react with KCl to form different potassium aluminium silicates. It indicates that chemical reactions play an important role in the overall capturing process. The effects of zeolite 24A and kaolin on sintering behaviors of the barley straw ash were also investigated. The residues from sintering tests were analyzed by a combination of X-Ray diffractometry (XRD) and scanning electron microscopy equipped with energy dispersive X-Ray analysis (SEM-EDX). The barley straw ash melted intensively at elevated temperatures. Together with XRD analysis, the SEM-EDX analysis results revealed that severe melting of the barley straw ash was due to formation and fusion of low temperature melting potassium silicates. Addition of kaolin and zeolite 24A significantly

  13. Co-combustion of agricultural wastes in a circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Huseyin Topal; Aysel T. Atimtay [Gazi University, Ankara (Turkey). Dept. of Mechanical Engineering

    2005-07-01

    In this study a circulating fluidized bed combustion (CFBC) of 125 mm inside diameter and 1800 mm height was used to investigate the co-combustion characteristics of peach and apricot stones produced as a waste from the fruit juice industry, and sunflower stems produced as a waste from the edible oil industry with a lignite coal. Lignite coal is a coal most widely used in Turkey. On-line concentrations of O{sub 2}, CO, CO{sub 2}, SO{sub 2}, NOx and total hydrocarbons (C{sub m}H{sub n}) were measured in the flue gas during combustion experiments. By changing the operating parameters the variation of emissions of various pollutants were studied. During combustion tests, it was observed that the volatile matter from agro-wastes quickly volatilizes and mostly burn in the riser. The temperature profiles along the bed and the rise also confirmed this phenomenon. It was found that as the volatile matter content of agro-waste increases, the combustion efficiency increases and the combustion takes place more in the upper region of the riser. These results suggest that agro-wastes are potential fuels that can be utilized for clean energy production by using CFBC in countries where agricultural activities are heavy. 3 refs., 4 figs., 5 tabs.

  14. Effects of biomass on dynamics of combustion in circulating fluidized beds

    Directory of Open Access Journals (Sweden)

    Tourunen Antti

    2004-01-01

    Full Text Available Fluidized bed technology is very suitable for the combustion of biomass Nevertheless substitution of coal with biomass affects boiler operation and especially dynamics and controllability. Non-homogeneity of biomass and fuel feeding disturbances cause process instability, such as variations in temperatures and pressures, which reduce lifetime of equipment and structures. Because of process instability higher air coefficient must be used in order to avoid CO emissions, which is not economical. Combustion profiles for coal, wood and peat, measured at the VTT Processes Pilot circulating fluidized bed reactor, have been compared. Process stability and char inventories have been studied by the measurements and the model. Biofuel are usually very reactive and their combustion profiles are quite different compared to coals. Because of high reactivity and low char content combustion process with biofuel is very sensitive for fuel feeding. Also low char inventory effect on load changes combined with combustion profile that differs from coals. Because of different combustion profile heat transfer can be a limiting factor in load changes despite the high reactivity and fast oxygen response.

  15. Volcanic ash in feed coal and its influence on coal combustion products

    Energy Technology Data Exchange (ETDEWEB)

    Brownfield, M.E.; Affolter, R.H.; Cathcart, J.D.; Brownfield, I.K.; Hower, J.C.; Stricker, G.D.; O' Connor, J.T.

    2000-07-01

    The US Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana Utility to determine the physical and chemical properties of feed coal and coal combustion products (CCPs) from a coal-fired power plant. The plant utilizes a low-sulfur (.23--.47 weight percent S) coal from the Powder River Basin, Wyoming. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis of feed coal samples identified two mineral suites. A primary suite (not authigenic) consisting of quartz (detrital and volcanic beta-form grains), biotite, and minor zircon and a secondary authigenic mineral suite containing calcite, alumino-phosphates (crandallite and gorceixite), kaolinite, quartz, anatase, barite, and pyrite. The authigenic minerals are attributed to air-fall and reworked volcanic ash that was deposited in peat-forming mires. The Powder River Basin feed coals contain higher amounts of Ba, Ca, Mg, Na, Sr, and P compared to other analyzed eastern coals. These elements are associated with alumino-phosphate, biotite, calcite, and clay minerals. The element associations are indicative of coal that incorporated volcanic ash during deposition. XRD analysis of CCPs revealed a predominance of glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals in the fly ash; and quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite in the bottom ash. Microprobe and SEM analysis of fly ash samples revealed quartz, zircon, monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, and rounded grains of wollastonite with periclase. The abundant Ca and Mg mineral phases in the fly ashes are related to the presence of carbonate, clay, and phosphate minerals in the feed coal. The Ca- and Mg-rich mineral phases in the CCPs can be attributed to volcanic minerals deposited in the

  16. Quantifying time in sedimentary successions by radio-isotopic dating of ash beds

    Science.gov (United States)

    Schaltegger, Urs

    2014-05-01

    Sedimentary rock sequences are an accurate record of geological, chemical and biological processes throughout the history of our planet. If we want to know more about the duration or the rates of some of these processes, we can apply methods of absolute age determination, i.e. of radio-isotopic dating. Data of highest precision and accuracy, and therefore of highest degree of confidence, are obtained by chemical abrasion, isotope-dilution, thermal ionization mass spectrometry (CA-ID-TIMS) 238U-206Pb dating techniques, applied to magmatic zircon from ash beds that are interbedded with the sediments. This techniques allows high-precision estimates of age at the 0.1% uncertainty for single analyses, and down to 0.03% uncertainty for groups of statistically equivalent 206Pb/238U dates. Such high precision is needed, since we would like the precision to be approximately equivalent or better than the (interpolated) duration of ammonoid zones in the Mesozoic (e.g., Ovtcharova et al. 2006), or to match short feedback rates of biological, climatic, or geochemical cycles after giant volcanic eruptions in large igneous provinces (LIP's), e.g., at the Permian/Triassic or the Triassic/Jurassic boundaries. We also wish to establish as precisely as possible temporal coincidence between the sedimentary record and short-lived volcanic events within the LIP's. Precision and accuracy of the U-Pb data has to be traceable and quantifiable in absolute terms, achieved by direct reference to the international kilogram, via an absolute calibration of the standard and isotopic tracer solutions. Only with a perfect control on precision and accuracy of radio-isotopic data, we can confidently determine whether two ages of geological events are really different, and avoid mistaking interlaboratory or interchronometer biases for age difference. The development of unprecedented precision of CA-ID-TIMS 238U-206Pb dates led to the recognition of protracted growth of zircon in a magmatic liquid (see

  17. Numerical modelling of biomass combustion: Solid conversion processes in a fixed bed furnace

    Science.gov (United States)

    Karim, Md. Rezwanul; Naser, Jamal

    2017-06-01

    Increasing demand for energy and rising concerns over global warming has urged the use of renewable energy sources to carry a sustainable development of the world. Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It is an eco-friendly source of energy as it reduces carbon dioxide emissions. Combustion of solid biomass is a complex phenomenon due to its large varieties and physical structures. Among various systems, fixed bed combustion is the most commonly used technique for thermal conversion of solid biomass. But inadequate knowledge on complex solid conversion processes has limited the development of such combustion system. Numerical modelling of this combustion system has some advantages over experimental analysis. Many important system parameters (e.g. temperature, density, solid fraction) can be estimated inside the entire domain under different working conditions. In this work, a complete numerical model is used for solid conversion processes of biomass combustion in a fixed bed furnace. The combustion system is divided in to solid and gas phase. This model includes several sub models to characterize the solid phase of the combustion with several variables. User defined subroutines are used to introduce solid phase variables in commercial CFD code. Gas phase of combustion is resolved using built-in module of CFD code. Heat transfer model is modified to predict the temperature of solid and gas phases with special radiation heat transfer solution for considering the high absorptivity of the medium. Considering all solid conversion processes the solid phase variables are evaluated. Results obtained are discussed with reference from an experimental burner.

  18. Combustion of peanut and tamarind shells in a conical fluidized-bed combustor: a comparative study.

    Science.gov (United States)

    Kuprianov, Vladimir I; Arromdee, Porametr

    2013-07-01

    Combustion of peanut and tamarind shells was studied in the conical fluidized-bed combustor using alumina sand as the bed material to prevent bed agglomeration. Morphological, thermogravimetric and kinetic characteristics were investigated to compare thermal and combustion reactivity between the biomass fuels. The thermogravimetric kinetics of the biomasses was fitted using the Coats-Redfern method. Experimental tests on the combustor were performed at 60 and 45 kg/h fuel feed rates, with excess air within 20-80%. Temperature and gas concentrations were measured along radial and axial directions in the reactor and at stack. The axial temperature and gas concentration profiles inside the combustor exhibited sensible effects of fuel properties and operating conditions on combustion and emission performance. High (≈ 99%) combustion efficiency and acceptable levels of CO, CxHy, and NO emissions are achievable when firing peanut shells at excess air of about 40%, whereas 60% is more preferable for burning tamarind shells. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Radioactivity of wood ash

    International Nuclear Information System (INIS)

    Rantavaara, A.; Moring, M.

    2000-01-01

    STUK (Finnish Radiation and Nuclear Safety Authority) has investigated natural and artificial radioactivity in wood ash and radiation exposure from radionuclides in ash since 1996. The aim was to consider both handling of ash and different ways of using ash. In all 87 ash samples were collected from 22 plants using entirely or partially wood for their energy production in 1996-1997. The sites studied represented mostly chemical forest industry, sawmills or district heat production. Most plants used fluidised bed combustion technique. Samples of both fly ash and bottom ash were studied. The activity concentrations of radionuclides in samples of, e.g., dried fly ash from fuel containing more than 80% wood were determined. The means ranged from 2000 to less than 50 Bq kg -1 , in decreasing order: 137 Cs, 40 K, 90 Sr, 210 Pb, 226 Ra, 232 Th, 134 Cs, 235 U. In bott radionuclide contents decreased in the same order as in fly ash, but were smaller, and 210 Pb was hardly detectable. The NH 4 Ac extractable fractions of activities for isotopes of alkaline elements (K, Cs) in bottom ash were lower than in fly ash, whereas solubility of heavier isotopes was low. Safety requirements defined by STUK in ST-guide 12.2 for handling of peat ash were fulfilled at each of the sites. Use of ash for land-filling and construction of streets was minimal during the sampling period. Increasing this type of ash use had often needed further investigations, as description of the use of additional materials that attenuate radiation. Fertilisation of forests with wood ash adds slightly to the external irradiation in forests, but will mostly decrease doses received through use of timber, berries, mushrooms and game meat. (orig.)

  20. Determination of mercury in ash and soil samples by oxygen flask combustion method-Cold vapor atomic fluorescence spectrometry (CVAFS)

    International Nuclear Information System (INIS)

    Geng Wenhua; Nakajima, Tsunenori; Takanashi, Hirokazu; Ohki, Akira

    2008-01-01

    A simple method was developed for the determination of mercury (Hg) in coal fly ash (CFA), waste incineration ash (WIA), and soil by use of oxygen flask combustion (OFC) followed by cold vapor atomic fluorescence spectrometry (CVAFS). A KMnO 4 solution was used as an absorbent in the OFC method, and the sample containing a combustion agent and an ash or soil sample was combusted by the OFC method. By use of Hg-free graphite as the combustion agent, the determination of Hg in ash and soil was successfully carried out; the Hg-free graphite was prepared by use of a mild pyrolysis procedure at 500 deg. C. For six certified reference materials (three CFA samples and three soil samples), the values of Hg obtained by this method were in good agreement with the certified or reference values. In addition, real samples including nine CFAs collected from some coal-fired power plants, five WIAs collected from waste incineration plants, and two soils were analyzed by the present method, and the data were compared to those from microwave-acid digestion (MW-AD) method

  1. Fly ash aggregates. Vliegaskunstgrind

    Energy Technology Data Exchange (ETDEWEB)

    1983-03-01

    A study has been carried out into artificial aggregates made from fly ash, 'fly ash aggregates'. Attention has been drawn to the production of fly ash aggregates in the Netherlands as a way to obviate the need of disposal of fly ash. Typical process steps for the manufacturing of fly ash aggregates are the agglomeration and the bonding of fly ash particles. Agglomeration techniques are subdivided into agitation and compaction, bonding methods into sintering, hydrothermal and 'cold' bonding. In sintering no bonding agent is used. The fly ash particles are more or less welded together. Sintering in general is performed at a temperature higher than 900 deg C. In hydrothermal processes lime reacts with fly ash to a crystalline hydrate at temperatures between 100 and 250 deg C at saturated steam pressure. As a lime source not only lime as such, but also portland cement can be used. Cold bonding processes rely on reaction of fly ash with lime or cement at temperatures between 0 and 100 deg C. The pozzolanic properties of fly ash are used. Where cement is applied, this bonding agent itself contributes also to the strength development of the artificial aggregate. Besides the use of lime and cement, several processes are known which make use of lime containing wastes such as spray dry absorption desulfurization residues or fluid bed coal combustion residues. (In Dutch)

  2. Gaseous emissions in pressurised fluidised-bed combustion. Analysis and summary of the pilot experiments

    International Nuclear Information System (INIS)

    Korpela, T.; Hippinen, I.; Konkola, M.

    1996-01-01

    The influence of operating conditions on gaseous emissions in pressurised fluidised-bed combustion have been studied. The research objectives have been behaviour of sulphur absorbents and reduction of sulphur dioxide emissions, reduction of nitrogen oxide emissions, release of vapour-phase alkalimetals and carbon monoxide emissions. The sulphur capture capacities of calcium-based sorbents under PFBC conditions have been studied at a pressurised fluidised-bed reactor and at a pressurised thermogravimetric apparatus. The project has also connected results of the experimental PFBC at HUT/EVO. (author)

  3. Numerical simulations of the industrial circulating fluidized bed boiler under air- and oxy-fuel combustion

    International Nuclear Information System (INIS)

    Adamczyk, Wojciech P.; Kozołub, Paweł; Klimanek, Adam; Białecki, Ryszard A.; Andrzejczyk, Marek; Klajny, Marcin

    2015-01-01

    Measured and numerical results of air-fuel combustion process within large scale industrial circulating fluidized bed (CFB) boiler is presented in this paper. For numerical simulations the industrial compact CFB boiler was selected. Numerical simulations were carried out using three-dimensional model where the dense particulate transport phenomenon was simultaneously modelled with combustion process. The fluidization process was modelled using the hybrid Euler-Lagrange approach. The impact of the geometrical model simplification on predicted mass distribution and temperature profiles over CFB boiler combustion chamber two kinds of geometrical models were used, namely the complete model which consist of combustion chamber, solid separators, external solid super-heaters and simplified boiler geometry which was reduced to the combustion chamber. The evaluated temperature and pressure profiles during numerical simulations were compared against measured data collected during boiler air-fuel operation. Collected data was also used for validating numerical model of the oxy-fuel combustion model. Stability of the model and its sensitivity on changes of several input parameters were studied. The comparison of the pressure and temperature profiles for all considered cases gave comparable trends in contrary to measured data. Moreover, some additional test was carried out the check the influence of radiative heat transfer on predicted temperature profile within the CFB boiler. - Highlights: • Hybrid Euler-Lagrange approach was used for modelling particle transport, air- and oxy-fuel combustion process. • Numerical results were validated against measured data. • The influence of different boiler operating conditions on calculated temperature profile was investigated. • New strategy for resolving particle transport in circulating fluidized bed was shown

  4. Removal of unburned carbon in fly ash produced in coal combustion process

    International Nuclear Information System (INIS)

    Velasquez V, Leonardo F; De La Cruz M, Javier F; Sanchez M, Jhon F

    2007-01-01

    The coal unburned in flying ashes obtained in the processes of coal combustion is the main disadvantage for its use in the industry of the construction. This material normally has a size of particle greater than the mineral material, therefore it is possible to be separated in a considerable percentage, obtaining double benefit: the reusability of unburned like fuel or precursor for the activated charcoal production and the use of the mineral material in the industry of the construction since the organic matter has retired him that disables its use. In this work it is experienced with a sifted technique of separation by for three obtained flying ash samples with different technology (travelling Grill, pneumatic injection and overturning grill), were made grain sized analyses with meshes of a diameter of particle greater to 0,589 mm, the short analyses were made to them next to the retained material in each mesh and the unburned percentage of removal was determined of. The technique was compared with other developing.

  5. Co-combustion of peach and apricot stone with coal in a bubbling fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Atimtay, Aysel T.; Kaynak, Burcak [Department of Environmental Engineering, Middle East Technical University, Ankara 06531 (Turkey)

    2008-02-15

    In this study a bubbling fluidized bed combustor (BFBC) having an inside diameter of 102 mm and a height of 900 mm was used to investigate the co-combustion characteristics of peach and apricot stones produced as a waste from the fruit juice industry with coal. A lignite coal was used for co-combustion. On-line concentrations of O{sub 2}, CO, CO{sub 2}, SO{sub 2}, NO{sub X} and total hydrocarbons (C{sub m}H{sub n}) were measured in the flue gas during combustion experiments. Variations of emissions of various pollutants were studied by changing the operating parameters (excess air ratio, fluidization velocity, and fuel feed rate). Temperature distribution along the bed was measured with thermocouples. For co-combustion of apricot and peach fruit stones with a lignite coal, various ratios of biomass to coal ranging from 0 to 100 wt.% were tested. For the peach stone co-combustion tests, efficiencies are about 98% and for the apricot stone co-combustion tests, efficiencies ranged between 94.7% and 96.9% for 25%, 50% and 75% of apricot stone in the fuel mixture. The results of this study have shown that as the biomass ratio in the fuel mixture increases, the combustion takes place at the upper regions of the main column. This causes higher temperatures in the freeboard than the bed. Also the CO and hydrocarbon (C{sub m}H{sub n}) emissions increase as the biomass percentage increases in the fuel mixture. This causes decrease in the combustion efficiency. These results suggest that peach and apricot stones are potential fuels that can be utilized for clean energy production in small-scale fruit juice industries by using BFBC. The percentage of peach stones or apricot stones in the fuel mixture is suggested to be below 50 wt.% in order to obtain the emission limits of EU. During the design of the BFBC, one has to be careful about the volatile matter (VM) content of the biomass. For the complete combustion of the VM, longer freeboard or secondary air addition should be

  6. Investigation of Catalytic effect sewage sludge combustion ash in the formation of HAPs

    Energy Technology Data Exchange (ETDEWEB)

    Fullana, A.; Sidhu, S.; Font, R.; Conesa, A.

    2002-07-01

    Incineration is a very important technique in the treatment of sewage sludge. In 1998 approximately 1,5 million and 2,5 million dry tons of sewage sludge were incinerated in the United States and European Union (EU), respectively. In 1985, only 10% of EU sludge was incinerated, but by 2005 approximately 40% of EU sludge is expected to be incinerated. Use of sewage sludge as agricultural fertilizer was considered the best application for sludge until it was discovered that the presence of heavy metals in sludge could contaminate farmland. The limitations facing landfills and recycling plants and the planned ban on sea disposal has led to the expectation that the role of incineration will increase in the future. The expected increase in sludge incineration has also led to increased scrutiny of the main drawback to the incineration of sewage sludge: the formation of hazard air pollutants (HAP). Sewage sludge incineration has been identified as a very important source of HAPs such as chloro benzenes, chloro phenols, and PCDD/Fs. One of the more important characteristics of sewage sludge incineration is the formation of large amounts of ash, which is rich in known HAP formation catalysts such as Cu and Fe. Thus, the sludge incineration ash is expected to play an important role in the formation of HAPs in the post-combustion zone of a sludge incinerator. in this paper, we present results of our investigation of the catalytic effect of sewage sludge ash on the formation of chloro benzenes and chloro phenols. In this study, pyrolytic gas from sewage sludge was used as reaction gas instead of the synthetic organic mix that has been used in most previous HAPs formation studies. (Author) 4 refs.

  7. Temporal measurements and kinetics of selenium release during coal combustion and gasification in a fluidized bed

    International Nuclear Information System (INIS)

    Shen, Fenghua; Liu, Jing; Zhang, Zhen; Yang, Yingju

    2016-01-01

    Highlights: • The temporal release of Se from coal combustion and gasification was measured. • Kinetic laws for Se release from coal combustion and gasification were determined. • The influences of temperature and chemical composition of flue gas were clarified. • The interactions of Se species with mineral affect the release kinetics of Se. - Abstract: The temporal release of selenium from coal during combustion and gasification in a fluidized bed was measured in situ by an on-line analysis system of trace elements in flue gas. The on-line analysis system is based on an inductively coupled plasma optical emission spectroscopy (ICP-OES), and can measure concentrations of trace elements in flue gas quantitatively and continuously. The results of on-line analysis suggest that the concentration of selenium in flue gas during coal gasification is higher than that during coal combustion. Based on the results of on-line analysis, a second-order kinetic law r(x) = 0.94e −26.58/RT (−0.56 x 2 −0.51 x + 1.05) was determined for selenium release during coal combustion, and r(x) = 11.96e −45.03/RT (−0.53 x 2 −0.56 x + 1.09) for selenium release during coal gasification. These two kinetic laws can predict respectively the temporal release of selenium during coal combustion and gasification with an acceptable accuracy. Thermodynamic calculations were conducted to predict selenium species during coal combustion and gasification. The speciation of selenium in flue gas during coal combustion differs from that during coal gasification, indicating that selenium volatilization is different. The gaseous selenium species can react with CaO during coal combustion, but it is not likely to interact with mineral during coal gasification.

  8. Experimental investigation of the oxy-fuel combustion of hard coal in a circulating fluidized-bed combustion; Experimentelle Untersuchung der Oxy-Fuel-Verbrennung von Steinkohle in einer zirkulierenden Wirbelschichtfeuerung

    Energy Technology Data Exchange (ETDEWEB)

    Hofbauer, Gerrit Arne

    2017-03-16

    The United Nations Framework Convention on Climate Change (UNFCCC) in 1992 first illustrated the social, economic and politic focus being placed on combating climate change caused by anthropogenic greenhouse gases. From there onwards research and development efforts have particularly centred on the reduction of CO{sub 2} emissions in the production of electrical power through the use of carbonaceous fossil fuels. The long-term goal is a conversion to sustainable and CO{sub 2} free means of producing power, utilizing in the main part renewable forms of energy such as solar, wind and hydro power. Currently, such renewable ways of creating electricity only represent a small percentage of global energy production. The technological and economic hurdles that are associated with a substantial increase of renewable energy production have greatly slowed their increased implementation. However, the goal of keeping the atmospheric CO{sub 2} concentration below 450 ppm requires a significantly faster reduction in the amount of greenhouse gas emissions. Therefore, considerations are being given to bridge technologies which would be able to capture and store the CO{sub 2} emissions from fossil fired power plants. These technologies are referred to as CCS (carbon capture and storage). Oxy-fuel combustion, combustion with pure oxygen instead of air, is one of those technologies and forms the focus of investigation of this work. The Institute of Combustion and Power Plant Technology in Stuttgart, Germany, have researched this matter, carrying out combustion experiments in its 150 kW{sub th} circulating fluidized bed pilot facility. The experiments were aimed at investigating the influence of excess oxygen, combustion temperature and inlet oxygen concentration on the combustion process and comparing air to oxy-fuel combustion. These results were compared to the results of fundamental investigations and combustion experiments carried out by other research groups. The relationship

  9. Proceedings of the Sixth International Conference on Fluidized Bed Combustion. Volume 1. Plenary sessions

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-08-01

    The Sixth International Conference on Fluidized Bed Combustion was held at the Atlanta Hilton, Atlanta, Georgia, April 9-11, 1980. The papers in this volume involved presentation of the research and development programs of the US (US DOE, TVA, EPRI and US EPA), United Kingdom, Federal Republic of Germany and the People's Republic of China. Eight papers from Vol. 1 (Plenary Sessions) of the proceedings have been entered individually into EDB and ERA. (LTN)

  10. Combustion of Dried Sewage Sludge in a Fluidized-Bed Reactor

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Trnka, Otakar

    2005-01-01

    Roč. 44, č. 10 (2005), s. 3432-3441 ISSN 0888-5885 R&D Projects: GA AV ČR(CZ) IAA4072201 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidized-bed combustion * dried sewage sludge * CO, NOx, and N2O emissions Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.504, year: 2005

  11. Proceedings of the sixth international conference on fluidized bed combustion. Volume III. Technical sessions

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-08-01

    The Sixth International Conference on Fluidized Bed Combustion was held April 9-11, 1980, at the Atlanta Hilton, Atlanta, Georgia. It was sponsored by the US Department of Energy, the Electric Power Research Institute, the US Environmental Protection Agency, and the Tennessee Valley Authority. Forty-five papers from Vol. III of the proceedings have been entered individually into EDB and ERA. Two papers had been entered previously from other sources. (LTN)

  12. Pressurized fluidized bed combustion combined cycle power plant with coal gasification: Second generation pilot plant

    International Nuclear Information System (INIS)

    Farina, G.L.; Bressan, L.

    1991-01-01

    This paper presents the technical and economical background of a research and development program of a novel power generation scheme, which is based on coal gasification, pressurized fluid bed combustion and combined cycles. The participants in this program are: Foster Wheeler (project leader), Westinghouse, IGT and the USA Dept. of Energy. The paper describes the characteristics of the plant, the research program in course of implementation, the components of the pilot plant and the first results obtained

  13. Effects of Fluidization Velocity and Bed Particle Size on Bed Defluidization during Biomass Combustion in FB boilers; Effekten av fluidiseringshastighet och kornstorlek paa agglomereringsrisk vid biobraensleeldning i FB-pannor

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Morgan; Oehman, Marcus [Umeaa Univ. (Sweden). Applied Physics and Electronics; Wikman, Karin; Berg, Magnus [AaF-Energi och Miljoe AB, Stockholm (Sweden)

    2004-11-01

    Studies on the effect of bed particle size and fluidization velocity on the agglomeration/defluidization risk during biomass combustion in BFB/CFB plants have not previously been published. Therefore, the objective of this project has been to determine the influence of these two parameters on the risk for agglomeration in typical biofuel fired fluidized beds. The study has also resulted in information on how variations in the coating characteristics of the bed particles are depending on the fuel ash content and the particle size of the bed material. Furthermore, the conditions at large scale commercial plants have been surveyed with respect to the choice of bed material, fluidization velocity, bed sand consumption etc. Bed materials have been sampled from seven full-scale boilers, four CFB and three BFB. The samples have been sieved to achieve sieve curves, analyzed with respect to the coating characteristics, and studied by experiments in a bench-scale fluidized bed. It could be concluded from the analyses that there are no significant differences in the coating thickness or the coating composition between fine and coarse particles in the bed samples. The bench-scale agglomeration experiments showed that increased fluidization velocity results in bed agglomeration at a higher temperature. This effect was stronger at relatively low fluidization velocities. The fluidization velocity has probably no significant effect on the risk for agglomeration at normal gas velocities in a commercial CFB boiler. Though, it could have an influence on the agglomeration in for example the recycling part of a CFB, where the gas velocity is relatively low. Also in BFB-boilers the fluidization velocity is often low enough to have a significant effect on the risk for agglomeration. By the experiments in this project it has not been possible to determine if the bed particle size has an influence on the agglomeration. Further studies with modified methods are required to find out if the

  14. Development of pressurized internally circulating fluidized bed combustion technology; Kaatsu naibu junkan ryudosho boiler no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, I [Center for Coal Utilization, Japan, Tokyo (Japan); Nagato, S; Toyoda, S [Ebara Corp., Tokyo (Japan)

    1996-09-01

    The paper introduced support research on element technology needed for the design of hot models of the pressurized internally circulating fluidized bed combustion boiler in fiscal 1995 and specifications for testing facilities of 4MWt hot models after finishing the basic plan. The support research was conduced as follows: (a) In the test for analysis of cold model fluidization, it was confirmed that each characteristic value of hot models is higher than the target value. Further, calculation parameters required for computer simulation were measured and data on the design of air diffusion nozzle for 1 chamber wind box were sampled. (b) In the CWP conveyance characteristic survey, it was confirmed that it is possible to produce CWP having favorable properties. It was also confirmed that favorable conveyability can be maintained even if the piping size was reduced down to 25A. (c) In the gas pressure reducing test, basic data required for the design of gas pressure reducing equipment were sampled. Specifications for the fluidized bed combustion boiler of hot models are as follows: evaporation amount: 3070kg/h, steam pressure: 1.77MPa, fuel supply amount: 600kg-coal/h, boiler body: cylinder shape water tube internally circulating fluidized bed combustion boiler. 4 refs., 4 figs.

  15. Measurement of alkali-vapor emission from pressurized fluidized-bed combustion of Illinois coals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.H.D.; Teats, F.G.; Swift, W.M. (Argonne National Lab., IL (United States)); Banerjee, D.D. (Illinois Clean Coal Inst., Carterville, IL (United States))

    1993-01-01

    Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were separately combusted in a laboratory-scale (15-cm dia) pressurized fluidized-bed combustor (PFBC) combined with an alkali sorber. These coals were combusted in a fluidized bed of Tymochtee dolomite at temperatures ranging from 910 to 950[degree]C and a system pressure of 9.2 atm absolute. Alkali-vapor emission (Na and K) in the PFBC flue gas was determined by the analytical activated-bauxite sorber bed technique developed at Argonne National Laboratory. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas, and that the level of sodium-vapor emission increases linearly with both Na and Cl contents in the coals. This suggests that the sodium-vapor emission results from direct vaporization of NaCl present in the coals. The measured alkali-vapor concentration (Na + K), 67 to 190 ppbW, is more than 2.5 times greater than the allowable alkali limit of 24 ppb for an industrial gas turbine. Combusting these coals in a PFBC for power generation may require developing a method to control alkali vapors.

  16. Measurement of alkali-vapor emission from pressurized fluidized-bed combustion of Illinois coals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.H.D.; Teats, F.G.; Swift, W.M. [Argonne National Lab., IL (United States); Banerjee, D.D. [Illinois Clean Coal Inst., Carterville, IL (United States)

    1993-04-01

    Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were separately combusted in a laboratory-scale (15-cm dia) pressurized fluidized-bed combustor (PFBC) combined with an alkali sorber. These coals were combusted in a fluidized bed of Tymochtee dolomite at temperatures ranging from 910 to 950{degree}C and a system pressure of 9.2 atm absolute. Alkali-vapor emission (Na and K) in the PFBC flue gas was determined by the analytical activated-bauxite sorber bed technique developed at Argonne National Laboratory. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas, and that the level of sodium-vapor emission increases linearly with both Na and Cl contents in the coals. This suggests that the sodium-vapor emission results from direct vaporization of NaCl present in the coals. The measured alkali-vapor concentration (Na + K), 67 to 190 ppbW, is more than 2.5 times greater than the allowable alkali limit of 24 ppb for an industrial gas turbine. Combusting these coals in a PFBC for power generation may require developing a method to control alkali vapors.

  17. Impact of co-combustion of petroleum coke and coal on fly ash quality: Case study of a Western Kentucky power plant

    International Nuclear Information System (INIS)

    Hower, James C.; Thomas, Gerald A.; Mardon, Sarah M.; Trimble, Alan S.

    2005-01-01

    Petroleum coke has been used as a supplement or replacement for coal in pulverized-fuel combustion. At a 444-MW western Kentucky power station, the combustion of nearly 60% petroleum coke with moderate- to high-sulfur Illinois Basin coal produces fly ash with nearly 50% uncombusted petroleum coke and large amounts of V and Ni when compared to fly ash from strictly pulverized coal burns. Partitioning of the V and Ni, known from other studies to be concentrated in petroleum coke, was noted. However, the distribution of V and Ni does not directly correspond to the amount of uncombusted petroleum coke in the fly ash. Vanadium and Ni are preferentially associated with the finer, higher surface area fly ash fractions captured at lower flue gas temperatures. The presence of uncombusted petroleum coke in the fly ash doubles the amount of ash to be disposed, makes the fly ash unmarketable because of the high C content, and would lead to higher than typical (compared to other fly ashes in the region) concentrations of V and Ni in the fly ash even if the petroleum coke C could be beneficiated from the fly ash. Further studies of co-combustion ashes are necessary in order to understand their behavior in disposal

  18. A Preliminary Study on Rock Bed Heat Storage from Biomass Combustion for Rice Drying

    Science.gov (United States)

    Nelwan, L. O.; Wulandani, D.; Subrata, I. D. M.

    2018-05-01

    One of the main constraints of biomass fuel utilization in a small scale rice drying system is the operating difficulties related to the adjustment of combustion/feeding rate. Use of thermal storage may reduce the problem since combustion operation can be accomplished in a much shorter time and then the use of heat can be regulated by simply adjusting the air flow. An integrated biomass furnace-rock bed thermal storage with a storage volume of 540 L was designed and tested. There were four experiments conducted in this study. Charging was performed within 1-2 hours with a combustion rate of 11.5-15.5 kg/h. In discharging process, the mixing of air passing through the rock bed and ambient air were regulated by valves. Without adjusting the valve during the discharging process, air temperature increased up to 80°C, which is not suitable for rice batch drying process. Charging with sufficiently high combustion rate (14 kg/h) within 1 hour continued by adjusting the valve during discharging process below 60°C increased the discharge-charge time ratio (DCTR) up to 5.33 at average air temperature of 49°C and ambient temperature of 33°C.The efficiency of heat discharging was ranged from 34.5 to 45.8%. From the simulation, as much as 156.8-268.8 kg of rice was able to be dried by the discharging conditions.

  19. Fly ashes from co-combustion as a filler material in concrete production; Anvaendning av energiaskor som fillermaterial vid betongtillverkning

    Energy Technology Data Exchange (ETDEWEB)

    Sundblom, Hillevi

    2004-01-01

    The Swedish concrete producers have decided to work towards a common goal to limit the production of concrete with naturally rounded aggregate. A consequence is when use of a substitute, crushed aggregate, the demand of filler material increases. During the last years ashes form the CFB boiler in Perstorp has been utilised as a filler material, with success, in concrete production at Sydsten, Malmoe, Sweden. To examine the potential of using Swedish fly ashes as a filler material in concrete production, have different Swedish fly ashes above been studied to see if they fit the requirements for a filler material. The fly ashes studied in the project can be divided into four different groups, considering fuel mix and boiler type; 1. Bio and sludge fired CFB/BFB boiler from the paper industry, 2. Bio and peat fired CFB/BFB boiler, 3. Pulverized peat/coal firing furnace, 4.Bio and peat fired grate-fired boiler. From Sydsten experiences of using Swedish fly ashes two demands have emerged concerning the chemical composition of the ashes. The total amount of chloride in the concrete should not be higher than 0,1% and the LOI, (Loss Of Ignition) must be less than 10 %. The different ash analyses showed that the fluidised bed boilers and pulverized firing furnaces, in this study, passed all the chemical requirements but the grate fire boilers had difficulties to fulfil the requirement of LOI. The ashes chosen to be studied in further rheological investigations in different fresh concrete mixtures were, Category 1 (Hallstavik's and Hyltebruk's papermill), Category 2 (Vaesteraas Vaermeverk och Vaertaverket) and from Category 3 (Vattenfall Vaerme Uppsala). The results presented an increased water consumption of ashes from paper mills comparing with the other ashes, a probable reason could be the shape of the ash grains. The experiments also showed that all ashes contributed to the final strength of the hardened concrete, the paper mill ashes also contributed to the

  20. In-situ treatment of acid mine waters using fluidized bed ash: Field study

    International Nuclear Information System (INIS)

    Everett, J.W.; Canty, G.A.

    1999-01-01

    A slurry of mine water and fluidized bed ash (FBA) was injected into an abandoned coal mine in eastern Oklahoma in July 1997. Oil-field technology was used to inject 1.8 Gg (418 tons) of FBA through five wells in 15 hours. Prior to injection the seep water had a pH of 4.4, was net acidic (acidity over 400 mg/L as CaCO 3 ), and had relatively high metal concentrations (in mg/L: Fe-200; Mn-7; and Al-6). After injection, during the period of effective treatment, the seep water had a pH above 6.0, less net acidity, and had lower metals concentrations (in mg/L: Fe-120; Mn-5; and Al-< PQL). When the treated seep water exited the mine, the dissolved metals oxidized and hydrolyzed. As the metals precipitated, the alkalinity introduced by the FBA was consumed and the pH dropped. However, the seep water characteristics upon entering the receiving stream were improved, compared to pre-injection. The resulting seep water quality is such that it is more amenable to further treatment by passive treatment methods, such as anoxic limestone drains or wetlands. Alkaline injection is a finite treatment process. Eventually, the added alkalinity is exhausted, at which time the seep returns to pre-injection conditions, necessitating another injection of ash. For the study discussed in this paper, the treatment lasted approximately 15 months. While the amount of alkalinity added to the mine could have potentially treated much more than a year's volume of seep water, it is believed that much of the injected alkalinity was unavailable in backwater areas in the mine. This alkalinity contributed little, if any, to the treatment of water flowing through the mine. Mine hydrology, especially during injection are crucial to treatment longevity

  1. Improved electrical efficiency and bottom ash quality on waste combustion plants. Appendix A1 to A3

    Energy Technology Data Exchange (ETDEWEB)

    Nesterov, I.; Jensen, Peter A.; Dam-Johansen, K.; Kloeft, H.; Boejer, M. (Technical Univ. of Denmark, Kgs. Lyngby (Denmark)); Mogensen, Erhardt (Babcock and Wilcox Voelund A/S, Esbjerg (Denmark))

    2010-07-01

    Investigations making it possible to evaluate and further develop concepts to improve electrical efficiency in a waste combustion plant were performed. Furthermore, one objective of the study was to investigate the possibilities of improving waste bottom ash leaching properties by use of a rotary kiln treatment. The project work included construction of a bench-scale rotary kiln, performing ash rotary kiln treatment experiments, conducting gas suction probe measurements on a waste incineration plant and making some concept evaluations. The influence of the rotary kiln thermal treatment on the leaching of Ca, Al, Si, Mg, Ba, Sr, Cl, Cu, Pb, Zn, Cr, Mo, sulfate, DOC and carbonate was determined. As a result of these tests, the rotary kiln thermal treatment of bottom ashes can be recommended for reducing the leaching of Cu, Pb, Cl, Zn and DOC; however, an increased leaching of Cr and Mo should be expected. The combustion conditions above the grate of a waste incineration plant were investigated and the release and concentration of volatile ash species in the flue gas such as Cl, Na, K, Ca, Pb, Zn and S were measured. The conducted measurements show that flue gas from grate sections 3 and 4 can produce a sufficiently hot flue gas that contains only low concentrations of corrosive species, and therefore can be used to increase superheater temperatures. Implementation of the so-called flue gas split concept together with other steam circle modifications on a waste combustion plant, and using a reasonable increase in final steam temperature from 400 to 500 deg. C, have the potential to increase electrical efficiency from 24 to 30% (with respect to lower fuel heating value) in a waste combustion plant. The appendices deal with incineration bottom ash leaching properties; design and construction of rotary kiln facility; manual to rotary kiln experiments. (Author)

  2. Improved electrical efficiency and bottom ash quality on waste combustion plants. Appendix A7 to A10

    Energy Technology Data Exchange (ETDEWEB)

    Hyks, J.; Astrup, T.; Jensen, Peter A.; Nesterov, I.; Boejer, M.; Frandsen, F.; Dam-Johansen, K.; Hedegaard Madsen, O.; Lundtorp, K. (Technical Univ. of Denmark, Kgs. Lyngby (Denmark)); Mogensen, Erhardt (Babcock and Wilcox Voelund A/S, Glostrup (Denmark))

    2010-07-01

    Investigations making it possible to evaluate and further develop concepts to improve electrical efficiency in a waste combustion plant were performed. Furthermore, one objective of the study was to investigate the possibilities of improving waste bottom ash leaching properties by use of a rotary kiln treatment. The project work included construction of a bench-scale rotary kiln, performing ash rotary kiln treatment experiments, conducting gas suction probe measurements on a waste incineration plant and making some concept evaluations. The influence of the rotary kiln thermal treatment on the leaching of Ca, Al, Si, Mg, Ba, Sr, Cl, Cu, Pb, Zn, Cr, Mo, sulfate, DOC and carbonate was determined. As a result of these tests, the rotary kiln thermal treatment of bottom ashes can be recommended for reducing the leaching of Cu, Pb, Cl, Zn and DOC; however, an increased leaching of Cr and Mo should be expected. The combustion conditions above the grate of a waste incineration plant were investigated and the release and concentration of volatile ash species in the flue gas such as Cl, Na, K, Ca, Pb, Zn and S were measured. The conducted measurements show that flue gas from grate sections 3 and 4 can produce a sufficiently hot flue gas that contains only low concentrations of corrosive species, and therefore can be used to increase superheater temperatures. Implementation of the so-called flue gas split concept together with other steam circle modifications on a waste combustion plant, and using a reasonable increase in final steam temperature from 400 to 500 deg. C, have the potential to increase electrical efficiency from 24 to 30% (with respect to lower fuel heating value) in a waste combustion plant. The appendices deal with the influence of kiln treatment on incineration bottom ash leaching; the influence of kiln treatment on corrosive species in deposits; operational strategy for rotary kiln; alkali/chloride release during refuse incineration on a grate. (Author)

  3. Improved electrical efficiency and bottom ash quality on waste combustion plants. Appendix A4 to A6

    Energy Technology Data Exchange (ETDEWEB)

    Kloeft, H.; Jensen, Peter A.; Nesterov, I.; Hyks, J.; Astrup, T. (Technical Univ. of Denmark, Kgs. Lyngby (Denmark)); Mogensen, Erhardt (Babcock and Wilcox Voelund A/S, Glostrup (Denmark))

    2010-07-01

    Investigations making it possible to evaluate and further develop concepts to improve electrical efficiency in a waste combustion plant were performed. Furthermore, one objective of the study was to investigate the possibilities of improving waste bottom ash leaching properties by use of a rotary kiln treatment. The project work included construction of a bench-scale rotary kiln, performing ash rotary kiln treatment experiments, conducting gas suction probe measurements on a waste incineration plant and making some concept evaluations. The influence of the rotary kiln thermal treatment on the leaching of Ca, Al, Si, Mg, Ba, Sr, Cl, Cu, Pb, Zn, Cr, Mo, sulfate, DOC and carbonate was determined. As a result of these tests, the rotary kiln thermal treatment of bottom ashes can be recommended for reducing the leaching of Cu, Pb, Cl, Zn and DOC; however, an increased leaching of Cr and Mo should be expected. The combustion conditions above the grate of a waste incineration plant were investigated and the release and concentration of volatile ash species in the flue gas such as Cl, Na, K, Ca, Pb, Zn and S were measured. The conducted measurements show that flue gas from grate sections 3 and 4 can produce a sufficiently hot flue gas that contains only low concentrations of corrosive species, and therefore can be used to increase superheater temperatures. Implementation of the so-called flue gas split concept together with other steam circle modifications on a waste combustion plant, and using a reasonable increase in final steam temperature from 400 to 500 deg. C, have the potential to increase electrical efficiency from 24 to 30% (with respect to lower fuel heating value) in a waste combustion plant. The appendices deal with collection of slags for the rotary kiln experiments; overview of the thermal treatment experiments - phase 1; a journal paper with the title ''Quantification of leaching from waste incineration bottom ash treated in a rotary kiln

  4. Thermal decomposition of selected chlorinated hydrocarbons during gas combustion in fluidized bed

    Directory of Open Access Journals (Sweden)

    Olek Malgorzata

    2013-01-01

    Full Text Available Abstract Background The process of thermal decomposition of dichloromethane (DCM and chlorobenzene (MCB during the combustion in an inert, bubbling fluidized bed, supported by LPG as auxiliary fuel, have been studied. The concentration profiles of C6H5CI, CH2Cl2, CO2, CO, NOx, COCl2, CHCl3, CH3Cl, C2H2, C6H6, CH4 in the flue gases were specified versus mean bed temperature. Results The role of preheating of gaseous mixture in fluidized bed prior to its ignition inside bubbles was identified as important factor for increase the degree of conversion of DCM and MCB in low bed temperature, in comparison to similar process in the tubular reactor. Conclusions Taking into account possible combustion mechanisms, it was identified that autoignition in bubbles rather than flame propagation between bubbles is needed to achieve complete destruction of DCM and MCB. These condition occurs above 900°C causing the degree of conversion of chlorine compounds of 92-100%.

  5. Improved electrical efficiency and bottom ash quality on waste combustion plants. Appendix A11 to A14

    Energy Technology Data Exchange (ETDEWEB)

    Hedegaard Madsen, O.; Boejer, M.; Jensen, Peter A.; Dam-Johansen, K.; Lundtorp, K. (Technical Univ. of Denmark, Kgs. Lyngby (Denmark)); Mogensen, Erhardt (Babcock and Wilcox Voelund A/S, Glostrup (Denmark))

    2010-07-01

    Investigations making it possible to evaluate and further develop concepts to improve electrical efficiency in a waste combustion plant were performed. Furthermore, one objective of the study was to investigate the possibilities of improving waste bottom ash leaching properties by use of a rotary kiln treatment. The project work included construction of a bench-scale rotary kiln, performing ash rotary kiln treatment experiments, conducting gas suction probe measurements on a waste incineration plant and making some concept evaluations. The influence of the rotary kiln thermal treatment on the leaching of Ca, Al, Si, Mg, Ba, Sr, Cl, Cu, Pb, Zn, Cr, Mo, sulfate, DOC and carbonate was determined. As a result of these tests, the rotary kiln thermal treatment of bottom ashes can be recommended for reducing the leaching of Cu, Pb, Cl, Zn and DOC; however, an increased leaching of Cr and Mo should be expected. The combustion conditions above the grate of a waste incineration plant were investigated and the release and concentration of volatile ash species in the flue gas such as Cl, Na, K, Ca, Pb, Zn and S were measured. The conducted measurements show that flue gas from grate sections 3 and 4 can produce a sufficiently hot flue gas that contains only low concentrations of corrosive species, and therefore can be used to increase superheater temperatures. Implementation of the so-called flue gas split concept together with other steam circle modifications on a waste combustion plant, and using a reasonable increase in final steam temperature from 400 to 500 deg. C, have the potential to increase electrical efficiency from 24 to 30% (with respect to lower fuel heating value) in a waste combustion plant. The appendices deal with electrical efficiency by dividing the combustion products; release of potentially corrosive constituents from the grate; CFD modeling of grate with and without vertical divider. (Author)

  6. Generating a representative signal of coal ash content to anticipate combustion control in a thermal power station

    International Nuclear Information System (INIS)

    Prieto-Fernandez, Ismael; Santurio-Diaz, J.M.; Folgueras-Diaz, B.; Lopez-Bobo, M. Rosario; Fernandez-Viar, P.

    2004-01-01

    This paper describes the possibilities of continuously measuring coal ash in the boiler feeding circuit of a thermal power station so that the measurement can be used as a signal for the boiler combustion control system. An installation was designed, at semi-industrial scale, that could faithfully reproduce the operation of a belt feeder. In order to measure the ash content, a natural radioactivity meter was installed and a large number of coal samples with different ranks and grain sizes were tested, eventually showing the possibility of achieving the objective

  7. Soil application of ash produced by low-temperature fluidized bed gasification: effects on soil nutrient dynamics and crop response

    DEFF Research Database (Denmark)

    Müller-Stöver, Dorette Sophie; Ahrenfeldt, Jesper; Holm, Jens Kai

    2012-01-01

    not significantly altered after ash application. SA was generally able to increase the levels of Olsen-P and of the ammonium acetate/acetic acid-extractable K in soil as well as to improve the yield of barley and maize, whereas faba bean did not react positively to ash amendment. CP did not show beneficial effects......Recycling of residual products of bioenergy conversion processes is important for adding value to the technologies and as a potential beneficial soil fertility amendment. In this study, two different ash materials originating from low temperature circulating fluidized bed (LT-CFB) gasification...... of either wheat straw (SA) or residue fibers mainly from citrus peels (CP) were tested regarding their potential to be used as fertilizer on agricultural soils. A soil incubation study, a greenhouse experiment with barley and faba bean, and an accompanying outdoor experiment with maize were carried out...

  8. The processing of bed ashes of fluidized bed boilers to an applicable ingredient for building materials. Het bewerken van bedassen van wervelbedketels tot een geschikte grondstof voor toepassing in bouwprodukten

    Energy Technology Data Exchange (ETDEWEB)

    Dekker, W

    1988-01-01

    A study- and test program has been carried out to determine in what way bed ashes of fluidized bed boilers can be processed to applicate the products in building products. The program consisted of selecting applicable ashes; physical-chemical research; slack lime, present in the ashes; grinding and wind-sifting of the ashes; evaluation of the quality of the acquired samples for application in calcium-silicate brick and in mortar; the making of flow-sheets of the processing in the potential demonstration projects. The used sample was a bed ash with active CaO content of 21%. Conclusions were stated and recommendations were made. 6 figs., 6 refs., 9 tabs., 2 app.

  9. Mineralogy and pore water chemistry of a boiler ash from a MSW fluidized-bed incinerator.

    Science.gov (United States)

    Bodénan, F; Guyonnet, D; Piantone, P; Blanc, P

    2010-07-01

    This paper presents an investigation of the mineralogy and pore water chemistry of a boiler ash sampled from a municipal solid waste fluidized-bed incinerator, subject to 18 months of dynamic leaching in a large percolation column experiment. A particular focus is on the redox behaviour of Cr(VI) in relation to metal aluminium Al(0), as chromium may represent an environmental or health hazard. The leaching behaviour and interaction between Cr(VI) and Al(0) are interpreted on the basis of mineralogical evolutions observed over the 18-month period and of saturation indices calculated with the geochemical code PhreeqC and reviewed thermodynamic data. Results of mineralogical analyses show in particular the alteration of mineral phases during leaching (e.g. quartz and metal aluminium grains), while geochemical calculations suggest equilibria of percolating fluids with respect to specific mineral phases (e.g. monohydrocalcite and aluminium hydroxide). The combination of leaching data on a large scale and mineralogical analyses document the coupled leaching behaviour of aluminium and chromium, with chromium appearing in the pore fluids in its hexavalent and mobile state once metal aluminium is no longer available for chromium reduction. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  10. Mineralogy and pore water chemistry of a boiler ash from a MSW fluidized-bed incinerator

    International Nuclear Information System (INIS)

    Bodenan, F.; Guyonnet, D.; Piantone, P.; Blanc, P.

    2010-01-01

    This paper presents an investigation of the mineralogy and pore water chemistry of a boiler ash sampled from a municipal solid waste fluidized-bed incinerator, subject to 18 months of dynamic leaching in a large percolation column experiment. A particular focus is on the redox behaviour of Cr(VI) in relation to metal aluminium Al 0 , as chromium may represent an environmental or health hazard. The leaching behaviour and interaction between Cr(VI) and Al 0 are interpreted on the basis of mineralogical evolutions observed over the 18-month period and of saturation indices calculated with the geochemical code PhreeqC and reviewed thermodynamic data. Results of mineralogical analyses show in particular the alteration of mineral phases during leaching (e.g. quartz and metal aluminium grains), while geochemical calculations suggest equilibria of percolating fluids with respect to specific mineral phases (e.g. monohydrocalcite and aluminium hydroxide). The combination of leaching data on a large scale and mineralogical analyses document the coupled leaching behaviour of aluminium and chromium, with chromium appearing in the pore fluids in its hexavalent and mobile state once metal aluminium is no longer available for chromium reduction.

  11. Experience in a 6.2 MW{sub e} pressurized fluidized bed gasifier with high ash Indian coals

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, G.; Rajasekaran, A.; Periyakaruppan, V.; Krishnamoorthy, S. [Bharat Heavy Electricals Ltd., Tiruchirappalli (India)

    2006-07-01

    Bharat Heavy Electrical Limited has installed a 165 tons/day air-blown pressurized fluidized bed gasifier (PFBG) as an add-on to their 6.2 MW IGCC demonstration plant and has operated it for more than 4000 hours. Improvements in the gasifier refractory lining, ash extraction and cooling devices, air distribution and temperature measuring devices were incorporated to improve the reliability and performance. Coal with 30-42% ash and high calorific value in the range of 15-20 MJ/kg was used during these operations with crushed coal of 1-4 mm as well as -6 mm coal with fines. Tests were conducted at gasifier pressure of 0.3-1.0 MPa, fluidized bed temperature of 980-1050{sup o}C and at various fluidized velocities and air to steam ratios. Once through carbon conversion efficiency of 90%, cold gas efficiency of 69% and dry gas calorific value of 4.4-4.6 MJ/Nm{sup 3} were obtained. About 15% char in fly ash (with 40% ash coal) was established by TGA. Seal pot system was added for recyling fly ash from the first cyclone to enhance carbon conversion, other parameters and to reduce the char in fly ash to acceptable level. Trends and correlations were established for constituents of gas, carbon conversion efficiency, cold gas efficiency, calorific value of gas and gas yield. BHEL is currently working with a partner to install a 125 MW IGCC plant. The paper elaborates the schematic and constructional details of the PFBG, operating experience and performance. 3 refs., 9 figs.

  12. State of the art and the future fuel portfolio of fluidized bed combustion systems; Status und kuenftiges Brennstoffportfolio bei Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Szentannai, Pal; Friebert, Arpad; Winter, Franz [Technische Univ. Wien (Austria). Inst. fuer Verfahrens-, Umwelttechnik und technische Biowissenschaften

    2008-07-01

    Coal, biomass and substitute fuels energetically can be used efficiently and with low pollution in fluidized bed plants. In comparison to biomass there are significant differences between the circulating and stationary fluidized bed technology. The stationary fluidised bed is fed predominantly with biomasses and residual substances. Coal usually is the basis fuel in the circulating fluidised bed. Biomass and residual substances frequently are course-fired. The state of the art is the employment of a broad fuel mixture in small and large fluidized-bed combustion systems. Future developments present an increased use of sewage sludge, fluidized bed combustion systems with wood as a basis fuel, utilization of household waste and the gas production.

  13. Ash formation and deposition in coal and biomass fired combustion systems: Progress and challenges in the field of ash particle sticking and rebound behavior

    DEFF Research Database (Denmark)

    Kleinhans, Ulrich; Wieland, Christoph; Frandsen, Flemming J.

    2018-01-01

    . The impaction of solid, molten or partially molten particles on surfaces is dependent on the particle and surface characteristics. For instance, a particulate deposit might capture incoming particles or be removed due to erosion, while a molten layer will collect all impacting particles, no matter...... if they are sticky or not. The main properties affecting the particle stickiness are the viscosity and surface tension for silicate-rich ashes. On the contrary, the stickiness of salt-rich ashes – typical for herbaceous biomass and wood- or waste-based fuels – is often described using the liquid melt fraction......, their required parameters are discussed and typical particle and surface properties found in combustion systems, are summarized. Eight different sticking criteria are implemented in a computational fluid dynamics code and computations are compared against measurements from an entrained flow reactor. Uniform...

  14. Particle size distribution of ashes and the behaviour of metals when firing Salix in a circulating fluidized bed boiler (CFB); Askans partikelfraktionsfoerdelning och metallernas beteende vid eldning av Salix i en CFB-panna

    Energy Technology Data Exchange (ETDEWEB)

    Sfiris, G; Johansson, A [Vattenfall Utveckling AB, Stockholm (Sweden); Valmari, T; Kauppinen, E; Pyykoenen, J; Lyyraenen, J [VTT Technical Research Centre of Finland, Espoo (Finland)

    1999-07-01

    This project is part of the Ash Recovery Programme aimed at establishing the environmental, technical and financial preconditions for returning wood ash to the forest. The programme is funded jointly by NUTEK, Sydkraft and Vattenfall. This report summarises the results of the experimental and modelling work to study the behaviour of the metals (especially Cd and K), after burning Salix in a 3-12 MW Circulating Fluidized Bed (CFB) boiler. The purpose of the study was to determine, using the experimental data, where cadmium and potassium condense, on what size particles they condense, and the decisive parameters governing these processes. Measurements of the fly ash particle size distribution carried out with a Berner Low Pressure Impactor (BLPI), coupled to a pre-cyclone. Samples were collected from three points: in the convection path at 650 deg C, after the convection path but before the secondary cyclone (160 deg C), and after the bag house (150 deg C). Wet chemical sampling was made for Cd, K, Zn and Pb, with three types of sampling equipment: collection of both particles and gas, collection of particles only, and analysis of the gas phase only. Analysis was made of samples from two places in the convection path (650 deg C and 250 deg C). Samples of bed material, bottom ash and fly ash have been subjected to scanning electron microscopy (SEM), and in addition a few fly ash particles, sampled after the convection path, were subjected to energy dispersive X-ray analysis (EDX). Based on experimental results, modelling work was carried out with an equilibrium model and with a general aerosol computer model ABC (Aerosol Behaviour in Combustion)

  15. Employment of fluidized bed ash as a basecourse material; Ryudosho nenshobai wo genryo to shita robanzai no jitsuyoka

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, I [Center for Coal Utilization, Japan, Tokyo (Japan); Tsuzura, K [Naruto Salt Mfg. Co. Ltd., Tokushima (Japan); Izumi, H [Nippon Hodo Co. Ltd., Tokyo (Japan); Goto, H [Electric Power Development Co. Ltd., Tokyo (Japan); Nagaoka, S [Kawasaki Heavy Industries, Ltd., Kobe (Japan)

    1996-09-01

    Generation of coal ash from coal burning fluidized beds reaches 400,000 tons annually, which is anticipated to increase still more in the future. This paper relates to works to develop a basecourse material manufacturing technology by utilizing excellent hydration and solidification characteristics of fluidized bed ash. The developmental works have been moved forward as a subsidy operation of the Agency of Natural Resources and Energy. Upon having obtained a prospect of practical application of the development, the research results are reported in this paper. Coal ash produced in a fluidized bed boiler goes through the following processes: it is added with water and kneaded; formed into rectangular parallelepiped having sides of 10 to 30 cm long by using a forming machine of vibrating and pressurizing type; cured in steam at 60 degC; crushed into sizes smaller than 40 mm; and made into a basecourse material upon adjusting the grain size. A pilot plant completed in 1993 has produced 15,000 tons of the material to date. Properties required as a basecourse material, such as hazardous metal dissolving characteristics and strength sufficiently meet relevant standards or the targeted value. Demonstration tests of the material on roads including public roads have shown as good result as those obtained from standard basecourse materials. 8 refs., 8 figs., 7 tabs.

  16. Increase in efficiency and reduction of generation cost at hard coal-fired power plants. Post-combustion of combustion residues from co-firing of RDF and biomass during dry ash removal

    Energy Technology Data Exchange (ETDEWEB)

    Baur, Guenter [Magaldi Power GmbH, Esslingen (Germany); Spindeldreher, Olaf [RWE Generation SE, Werne (Germany); RWE Generation SE, Essen (Germany)

    2013-09-01

    Secondary as well as substitute fuels are being used in hard coal-fired power plants to improve efficiency and to enlarge fuel flexibility. However, grinding and firing systems of the existing coal-fired plants are not designed for those co-fuels. Any deterioration of the combustion performance would reduce the power output and increase ash disposal costs by increased content of combustion residues. The application of air-cooled ash removal, with simultaneous and controlled post-combustion of unburned residues on the conveyor belt, enlarges the furnace and maintains combustion efficiency even with different fuel qualities. Plant efficiency can also be increased through heat recovery. (orig.)

  17. Combustion of mediterranean agro-forest biomasses in small and medium scale pellet boilers: strategies for minimizing ash fusion and slagging

    Energy Technology Data Exchange (ETDEWEB)

    Vega-Nieva, Daniel J.; Dopazo, Raquel; Ortiz, Luis [Forest Engineering Univ. School. Univ. of Vigo, Pontevedra (Spain)], e-mail: DanielJVN@gmail.com

    2012-11-01

    The slagging and fouling risk remain as important barriers that are currently limiting the use of various agricultural residues and potential energy crops feedstocks (e.g. [1-3]), which remain largely unutilized, particularly in Mediterranean countries. In this oral communication, the main results from the VI Framework European Project Domoheat on the combustion of mediterranean biomasses and its mixtures on small and medium size domestic pellet boilers, are presented, together with the goals of the ongoing VII Framework European Project AshMelT focusing on the definition of objective criteria and tests for ash slagging in domestic pellet boilers. The utilization of ash slagging indices based on ash composition and the definition of biomass mixtures based on such ash indices are presented as potentially useful tools for minimizing the occurrence of ash fusion and slagging during combustion.

  18. Pressurized Fluidized Bed Combustion Second-Generation System Research and Development

    Energy Technology Data Exchange (ETDEWEB)

    A. Robertson; D. Horazak; R. Newby; H. Goldstein

    2002-11-01

    Research is being conducted under United States Department of Energy (DOE) Contract DE-AC21-86MC21023 to develop a new type of coal-fired plant for electric power generation. This new type of plant--called a Second-Generation or Advanced Pressurized Circulating Fluidized Bed Combustion (APCFB) plant--offers the promise of efficiencies greater than 45% (HHV), with both emissions and a cost of electricity that are significantly lower than conventional pulverized-coal-fired plants with scrubbers. The APCFB plant incorporates the partial gasification of coal in a carbonizer, the combustion of carbonizer char in a pressurized circulating fluidized bed boiler (PCFB), and the combustion of carbonizer syngas in a topping combustor to achieve gas turbine inlet temperatures of 2300 F and higher. A conceptual design was previously prepared for this new type of plant and an economic analysis presented, all based on the use of a Siemens Westinghouse W501F gas turbine with projected carbonizer, PCFB, and topping combustor performance data. Having tested these components at the pilot plant stage, the referenced conceptual design is being updated to reflect more accurate performance predictions together with the use of the more advanced Siemens Westinghouse W501G gas turbine and a conventional 2400 psig/1050 F/1050 F/2-1/2 in. steam turbine. This report describes the updated plant which is projected to have an HHV efficiency of 48% and identifies work completed for the October 2001 through September 2002 time period.

  19. Chemical-looping combustion in a reverse-flow fixed bed reactor

    International Nuclear Information System (INIS)

    Han, Lu; Bollas, George M.

    2016-01-01

    A reverse-flow fixed bed reactor concept for CLC (chemical-looping combustion) is explored. The limitations of conventional fixed bed reactors, as applied to CLC, are overcome by reversing the gas flow direction periodically to enhance the mixing characteristics of the bed, thus improving oxygen carrier utilization and energy efficiency with respect to power generation. The reverse-flow reactor is simulated by a dusty-gas model and compared with an equivalent fixed bed reactor without flow reversal. Dynamic optimization is used to calculate conditions at which each reactor operates at maximum energy efficiency. Several cases studies illustrate the benefits of reverse-flow operation for the CLC with CuO and NiO oxygen carriers and methane and syngas fuels. The results show that periodic reversal of the flow during reduction improves the contact between the fuel and unconverted oxygen carrier, enabling the system to suppress unwanted catalytic reactions and axial temperature and conversion gradients. The operational scheme presented reduces the fluctuations of temperature during oxidation and increases the high-temperature heat produced by the process. CLC in a reverse-flow reactor has the potential to achieve higher energy efficiency than conventional fixed bed CLC reactors, when integrated with a downstream gas turbine of a combined cycle power plant. - Highlights: • Reverse-flow fixed bed CLC reactors for combined cycle power systems. • Dynamic optimization tunes operation of batch and transient CLC systems. • The reverse-flow CLC system provides stable turbine-ready gas stream. • Reverse-flow CLC fixed bed reactor has superior CO 2 capture and thermal efficiency.

  20. ESTABLISHMENT OF AN ENVIRONMENTAL CONTROL TECHNOLOGY LABORATORY WITH A CIRCULATING FLUIDIZED-BED COMBUSTION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Wei-Ping Pan; Andy Wu; John T. Riley

    2005-04-30

    This report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period January 1, 2005 through March 31, 2005. The following tasks have been completed. First, the renovation of the new Combustion Laboratory is nearly complete, and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building is in the final stages. Second, the fabrication and manufacture of the CFBC Facility is being discussed with a potential contractor. Discussions with potential contactor regarding the availability of materials and current machining capabilities have resulted in the modification of the original designs. The selection of the fabrication contractor for the CFBC Facility is expected during the next quarter. Third, co-firing experiments conducted with coal and chicken waste have been initiated in the laboratory-scale simulated fluidized-bed facility. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described in this report.

  1. The Impact of Coal Combustion Fly Ash Used as a Supplemental Cementitious Material on the Leaching of Constituents from Cements and Concretes

    Science.gov (United States)

    The objective of this report is to compare the leaching of portland cement-based materials that have been prepared with and without coal combustion fly ash to illustrate whether there is evidence that the use of fly ash in cement and concrete products may result in increased leac...

  2. Characterising boiler ash from a circulating fluidised bed municipal solid waste incinerator and distribution of PCDD/F and PCB.

    Science.gov (United States)

    Zhang, Mengmei; Buekens, Alfons; Li, Xiaodong

    2018-05-31

    In this study, ash samples were collected from five locations situated in the boiler of a circulating fluidised bed municipal solid waste incinerator (high- and low-temperature superheater, evaporator tubes and upper and lower economiser). These samples represent a huge range of flue gas temperatures and were characterised for their particle size distribution, surface characteristics, elemental composition, chemical forms of carbon and chlorine and distribution of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and biphenyls (PCB). Enrichment of chlorine, one of the main elements of organochlorinated pollutants, and copper, zinc and lead, major catalytic metals for dioxin-like compounds, was observed in lower-temperature ash deposits. The speciation of carbon and chlorine on ash surfaces was established, showing a positive correlation between organic chlorine and oxygen-containing carbon functional groups. The load of PCDD/F and PCB (especially dioxin-like PCB) tends to rise rapidly with falling temperature of flue gas, reaching their highest value in economiser ashes. The formation of PCDD/F congeners through the chlorophenol precursor route apparently was enhanced downstream the boiler. Principal component analysis (PCA) was applied to study the links between the ash characteristics and distribution of chloro-aromatics. The primary purpose of this study is improving the understanding of any links between the characteristics of ash from waste heat systems and its potential to form PCDD/F and PCB. The question is raised whether further characterisation of fly ash may assist to establish a diagnosis of poor plant operation, inclusive the generation, destruction and eventual emission of persistent organic pollutants (POPs).

  3. Naturally Occurring Radionuclides of Ash Produced by Coal Combustion. The Case of the Kardia Mine in Northern Greece

    Science.gov (United States)

    Fotakis, M.; Tsikritzis, L.; Tzimkas, N.; Kolovos, N.; Tsikritzi, R.

    2008-08-01

    West Macedonia Lignite Center (WMLC), located in Northwest Greece, releases into the atmosphere about 21,400 tons/year of fly ash through the stacks of four coal fired plants. The lignite ash contains naturally occurring radionuclides, which are deposited on the WMLC basin. This work investigates the natural radioactivity of twenty six ash samples, laboratory produced from combustion of lignite, which was sampled perpendicularly to the benches of the Kardia mine. The concentrations of radionuclides 40K, 235U, 238U, 226Ra, 228Ra and 232Th, were measured spectroscopically and found round one order of magnitude as high as those of lignite. Subsequently the Radionuclide Partitioning Coefficients of radionuclides were calculated and it was found that they are higher for 232Th, 228Ra and 40K, because the latter have closer affinity with the inorganic matrix of lignite. During combustion up to one third of the naturally occurring radioisotopes escape from the solid phase into the flue gases. With comparison to relative global data, the investigated ash has been found to have relatively high radioactivity, but the emissions of the WMLC radionuclides contribute only 0.03% to the mean annual absorbed dose.

  4. Naturally Occurring Radionuclides of Ash Produced by Coal Combustion. The Case of the Kardia Mine in Northern Greece

    International Nuclear Information System (INIS)

    Fotakis, M.; Tsikritzis, L.; Tzimkas, N.; Kolovos, N.; Tsikritzi, R.

    2008-01-01

    West Macedonia Lignite Center (WMLC), located in Northwest Greece, releases into the atmosphere about 21,400 tons/year of fly ash through the stacks of four coal fired plants. The lignite ash contains naturally occurring radionuclides, which are deposited on the WMLC basin. This work investigates the natural radioactivity of twenty six ash samples, laboratory produced from combustion of lignite, which was sampled perpendicularly to the benches of the Kardia mine. The concentrations of radionuclides 40 K, 235 U, 238 U, 226 Ra, 228 Ra and 232 Th, were measured spectroscopically and found round one order of magnitude as high as those of lignite. Subsequently the Radionuclide Partitioning Coefficients of radionuclides were calculated and it was found that they are higher for 232 Th, 228 Ra and 40 K, because the latter have closer affinity with the inorganic matrix of lignite. During combustion up to one third of the naturally occurring radioisotopes escape from the solid phase into the flue gases. With comparison to relative global data, the investigated ash has been found to have relatively high radioactivity, but the emissions of the WMLC radionuclides contribute only 0.03% to the mean annual absorbed dose

  5. Gaseous emissions from sewage sludge combustion in a moving bed combustor.

    Science.gov (United States)

    Batistella, Luciane; Silva, Valdemar; Suzin, Renato C; Virmond, Elaine; Althoff, Chrtistine A; Moreira, Regina F P M; José, Humberto J

    2015-12-01

    Substantial increase in sewage sludge generation in recent years requires suitable destination for this residue. This study evaluated the gaseous emissions generated during combustion of an aerobic sewage sludge in a pilot scale moving bed reactor. To utilize the heat generated during combustion, the exhaust gas was applied to the raw sludge drying process. The gaseous emissions were analyzed both after the combustion and drying steps. The results of the sewage sludge characterization showed the energy potential of this residue (LHV equal to 14.5 MJ kg(-1), db) and low concentration of metals, polycyclic aromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). The concentration of CO, NOx, BTEX (benzene, toluene, ethylbenzene and xylenes) emitted from the sludge combustion process were lower than the legal limits. The overall sludge combustion and drying process showed low emissions of PCDD/PCDF (0.42 ng I-TEQ N m(-3)). BTEX and PAH emissions were not detected. Even with the high nitrogen concentration in the raw feed (5.88% db), the sludge combustion process presented NOx emissions below the legal limit, which results from the combination of appropriate feed rate (A/F ratio), excess air, and mainly the low temperature kept inside the combustion chamber. It was found that the level of CO emissions from the overall sludge process depends on the dryer operating conditions, such as the oxygen content and the drying temperature, which have to be controlled throughout the process in order to achieve low CO levels. The aerobic sewage sludge combustion process generated high SO2 concentration due to the high sulfur content (0.67 wt%, db) and low calcium concentration (22.99 g kg(-1)) found in the sludge. The high concentration of SO2 in the flue gas (4776.77 mg N m(-3)) is the main factor inhibiting PCDD/PCDF formation. Further changes are needed in the pilot plant scheme to reduce SO2 and particulate matter emissions

  6. Co-combustion of coal and non-recyclable paper and plastic waste in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    D. Boavida; P. Abelha; I. Gulyurtlu; I. Cabrita [DEECA-INETI, Lisbon (Portugal)

    2003-10-01

    Co-combustion of waste with coal was carried out using a fluidised bed combustor with the aim of achieving a fuel mixture with little variations in its heating value and simultaneously reducing the accumulation of non-toxic waste material by upgrading them for energy purposes. Results obtained indicate that the feeding of waste materials plays an important role to achieve conditions for a stable combustion. The form in which the fuel is fed to the combustor makes a significant contribution to achieve desirable combustion performance and differences were observed in results regarding the combustion efficiency and emissions when waste was fed densified or in a fluffy state when it was burned mixed with coal. Part of the combustion of waste material, contrary to that of coal, was observed to take place in the freeboard where the temperature was as much as 150{sup o}C above that of the bed. 15 refs., 8 figs., 8 tabs.

  7. Process and technological wastes compaction through a fluidized bed incineration process

    International Nuclear Information System (INIS)

    Guiroy, J.J.

    1993-01-01

    The various fluidized bed systems (dense or circulating) are reviewed and the advantages of the circulation fluidized bed are highlighted (excellent combustion performance, clean combustion, large operating range, poly-functionality with regards to waste type, ...). Applications to contaminated graphite (with the problem of ash management) and to plant process wastes (ion exchangers, technological wastes, aqueous effluents); study of the neutralization and chlorine emission

  8. Investigation of combustion of coal briquettes in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Boavida, Dulce; Abelha, Pedro; Gulyurtlu, Ibrahim; Cabrita, Isabel

    1999-07-01

    This paper discusses the results obtained from an experimental combustion work undertaken to investigate the behaviour of multicomponent briquettes, prepared by mixing two different particle sizes of coal and two different types of binder species. single briquettes were burned over a wide range of temperatures in a laboratory scale fluidised bed combustor facility. Nitrogen (NO{sub x}, and N{sub 2}O) and Sulphur (SO{sub 2}) oxides emissions resulting from the combustion of these briquettes were constantly monitored during the time of burning. The levels of O{sub 2}, CO{sub 2} and CO were also recorded during the same period. Experimental results showed that coal particle size influenced burn-out times and emissions levels of some of gaseous species. The hinder type was also found to have a major influence on the emissions of different pollutants.The temperature was observed to significantly influence the extent of the effects of the other operating parameters studied.

  9. Experimental Investigations of Extracted Rapeseed Combustion Emissions in a Small Scale Stationary Fluidized Bed Combustor

    Directory of Open Access Journals (Sweden)

    Dieter Steinbrecht

    2009-02-01

    Full Text Available The objective of this study was to observe the combustion process of extracted rapeseed (ER grist in a stationary fluidized bed combustor (SFBC and evaluate the chemical compositions of the flue gas emissions. The experimental tests of ER combustion in the 90 to 200 kW (Kilowatt SFB combustion test facility show that the optimal ER combustion temperature is within the range from 850 to 880° C. Temperature and the concentration of exhausted emissions (e.g. O2, CO, CO2, NO, NO2, SO2, Corg were measured with dedicated sensors distributed within the combustor, along its height and in the flue gas duct. The experimental results showed that with respect to German emission limits the concentration of SO2 and NOx in the flue gas were high whereas that of CO was low. This study furthermore is applicable for the abundant biomass residue resources in Vietnam (rice husk, rice straw, bagasse, cassava residues, coconut shell etc., which have similar chemical compositions to ER.

  10. Experimental investigations of extracted rapeseed combustion emissions in a small scale stationary fluidized bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Dinh Tung, N.; Steinbrecht, D. [Rostock University, Faculty of Mechanical Engineering and Marine Technology, Chair of Environmental Technology, Justus-von-Liebig-Weg 6, D - 18059 Rostock (Germany); Tung, N. D. [Hanoi University of Agriculture- Hanoi/Vietnam, Faculty of Mechanical Engineering, Trau Quy - Gia Lam - Hanoi (Viet Nam); Vincent, T. [Rostock University, Chair of Energy Systems, Justus-von-Liebig-Weg 6, D - 18059 Rostock (Germany)

    2009-07-01

    The objective of this study was to observe the combustion process of extracted rapeseed (ER) grist in a stationary fluidized bed combustor (SFBC) and evaluate the chemical compositions of the flue gas emissions. The experimental tests of ER combustion in the 90 to 200 kW SFB combustion test facility show that the optimal ER combustion temperature is within the range from 850 to 880 {sup o}C. Temperature and the concentration of exhausted emissions (e.g. O{sub 2}, CO, CO{sub 2}, NO, NO{sub 2}, SO{sub 2}, C{sub org}) were measured with dedicated sensors distributed within the combustor, along its height and in the flue gas duct. The experimental results showed that with respect to German emission limits the concentration of SO{sub 2} and NO{sub x} in the flue gas were high whereas that of CO was low. This study furthermore is applicable for the abundant biomass residue resources in Vietnam (rice husk, rice straw, bagasse, cassava residues, coconut shell etc.), which have similar chemical compositions to ER. (author)

  11. Results concerning a clean co-combustion technology of waste biomass with fossil fuel, in a pilot fluidised bed combustion facility

    Energy Technology Data Exchange (ETDEWEB)

    Ionel, Ioana; Trif-Tordai, Gavril; Ungureanu, Corneliu; Popescu, Francisc; Lontis, Nicolae [Politehnica Univ. Timisoara (Romania). Faculty for Mechanical Engineering

    2008-07-01

    The research focuses on a facility, the experimental results, interpretation and future plans concerning a new developed technology of using waste renewable energy by applying the cocombustion of waste biomass with coal, in a fluidised bed system. The experimental facility is working entirely in accordance to the allowed limits for the exhaust flue gas concentration, with special concern for typical pollutants. The experiments conclude that the technology is cleaner, has as main advantage the possibility to reduce both the SO{sub 2} and CO{sub 2} exhaust in comparison to standard fossil fuel combustion, under comparable circumstances. The combustion is occurring in a stable fluidised bed. (orig.)

  12. Biomass fueled fluidized bed combustion: atmospheric emissions, emission control devices and environmental regulations

    International Nuclear Information System (INIS)

    Grass, S.W.; Jenkins, B.M.

    1994-01-01

    Fluidized bed combustors have become the technological choice for power generation from biomass fuels in California. Atmospheric emission data obtained during compliance tests are compared for five operating 18 to 32 MW fluidized bed combustion power plants. The discussion focuses on the impact of fuel properties and boiler design criteria on the emission of pollutants, the efficiency of pollution control devices, and regulations affecting atmospheric emissions. Stack NO x emission factors are shown not to vary substantially among the five plants which burn fuels with nitrogen concentrations between 0.3 and 1.1% dry weight. All facilities use at least one particular control device, but not all use limestone injection or other control techniques for sulfur and chlorine. The lack of control for chlorine suggests the potential for emission of toxic species due to favorable temperature conditions existing in the particulate control devices, particularly when burning fuels containing high concentrations of chlorine. (Author)

  13. N2 O A greenhouse gas released from the combustion of coals in fluidized beds

    International Nuclear Information System (INIS)

    Boavida, D.; Lobo, L. S.; Gulyurtlu, I.; Cabrita, I.

    1996-01-01

    This paper discusses the results of the experimental work investigating the formation of N-2 O and NO during fluidized bed combustion of coals, and of chars and volatiles produced from the pyrolysis of these coals. Ammonia (N H 3 ) and hydrogen cyanide (HCN) are shown to play important roles as gas phase precursors of both NO and N 2 O. The conversion of fuel-N through N H 3 and HCN to N 2 O and NO was studied using a fluidized bed combustor in the temperature range between 973 K and 1273 K, for two different coals. The results suggest that the principal contribution to N 2 O emission Originated from volatile-N, however, char-N could also have an important role, depending upon the temperature. 1 fig., 8 tabs

  14. Impact of Coal Fly Ash Addition on Combustion Aerosols (PM2.5) from Full-Scale Suspension-Firing of Pulverized Wood

    DEFF Research Database (Denmark)

    Damø, Anne Juul; Wu, Hao; Frandsen, Flemming

    2014-01-01

    The formation of combustion aerosols was studied in an 800 MWth suspension-fired power plant boiler, during combustion of pulverized wood pellets with and without addition of coal fly ash as alkali capture additive. The aerosol particles were sampled and characterized by a low-pressure cascade im...

  15. Sedimentary cycles and volcanic ash beds in the Lower Pliocene lacustrine succession of Ptolemais (NW Greece): discrepancy between 40 Ar/39 Ar and astronomical ages

    NARCIS (Netherlands)

    Steenbrink, J.; Vugt, N. van; Hilgen, F.J.; Wijbrans, J.R.; Meulenkamp, J.E.

    1999-01-01

    A high-resolution cyclostratigraphy for the rhythmically bedded lignite-marl sequences of the Lower Pliocene Ptole-mais Formation is combined with 40 Ar= 39 Ar dating results of intercalated volcanic ash beds. Detailed field reconnaissance in three open-pit lignite mines reveals three end-member

  16. Phosphorite ash in coal of certain beds of the Orzeskich (Zaleskich) layers. [Poland

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, J

    1982-01-01

    In ashes from coals of the Orzeskich (Zaleskich) layers, the variable content of P/sub 2/O/sub 5/ (0.4-1.15%) rises in an inverse proportion to the ash content of the coal. Chemical and mineral compositions of the ash in the coals of two levels of the mine ''Manifest Liptsovy'' are presented. The coal which yields phosphorite ash belongs to the type G. The phosphorus is mainly fruits and seeds of swamp plants. The smaller part of the phosphorus is formed by influx of terrigenous and volcanic material, as well as hydrothermal solutions.

  17. Behavior of Alkali Metals and Ash in a Low-Temperature Circulating Fluidized Bed (LTCFB) Gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas; Jensen, Peter Arendt; Henriksen, Ulrik Birk

    2016-01-01

    W and a 6 MW LTCFBgasifier. Of the total fuel ash entering the system, the largest fraction (40−50%) was retained in the secondary cyclone bottoms,while a lower amount (8−10%) was released as dust in the exit gas. Most of the alkali and alkaline earth metals were retained inthe solid ash, along with Si...... by the particle size and the cut size ofthe primary and secondary cyclones. A model accounting for the ash collection by the plant cyclones was shown to predict theproduct gas ash particle release reasonably well....

  18. Formation and destruction mechanisms of nitrogen oxides during coal combustion in circulating fluidized beds; Mecanismes de formation et de destruction des oxydes d`azote lors de la combustion du charbon en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Borrel, G.; Lecuyer, I. [Universite du Haut-Rhin, 68 - Mulhouse (France)

    1997-01-01

    Formation and reduction of nitrogen oxides (NO and N{sub 2}O) during coal combustion in a circulating fluidized bed (CFBC) are very complicated and yet badly known. The aim of the present study was to better characterize these phenomena on a small-sized experimental unit (reactor diameter: 5 cm), with the possibility to re-inject the solids in the bottom of the furnace, as in a real industrial unit. This should allow then to develop a numerical set of chemical reactions involving the nitrogen oxides. The experimental results showed that coal ash plays a great role in reducing nitrogen oxides, the determining parameter being the quantity of unburnt carbon remaining in the ash. The study then detailed the interaction between nitrogen oxides and de-volatilized (char) according to the temperature, NO{sub x} concentration and the mass of solid. In the absence of oxygen small quantities of char can very significantly reduce NO as well as N{sub 2}O. It was possible to establish destruction kinetics on these particles, and orders of reaction could be determined versus the NO{sub x} concentration and the char particle mass (heterogeneous phase chemical reactions). Then, the coal pyrolysis study enabled to identify the products released during coal devolatilization and thermogravimetric analyses displayed several successive weight losses due CO, CO{sub 2} and CH{sub 4} releases, during a linear temperature increase. Lastly coal combustion was studied in the small pilot with variable experimental conditions. Using the previous experimental was studied in the small pilot with variable experimental conditions. Using the previous experimental results, a model was developed to calculate NO{sub x} concentrations during the coal combustion and validated. The NO and N{sub 2}O contents calculated are thoroughly correlated with the experimental data whatever the injection carbon/oxygen ratio is. (author) 96 refs.

  19. The effect of low-NOx combustion on residual carbon in fly ash and its adsorption capacity for air entrainment admixtures in concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Jensen, Anker Degn; Dam-Johansen, Kim

    2010-01-01

    been combusted in an entrained flow reactor to test the impact of changes in operating conditions and fuel type on the AEA adsorption of ash and NOx formation. Increased oxidizing conditions, obtained by improved fuel-air mixing or higher excess air, decreased the AEA requirements of the produced ash......Fly ash from pulverized coal combustion contains residual carbon that can adsorb the air-entraining admixtures (AEAs) added to control the air entrainment in concrete. This is a problem that has increased by the implementation of low-NOx combustion technologies. In this work, pulverized fuel has...... by up to a factor of 25. This was due to a lower carbon content in the ash and a lower specific AEA adsorptivity of the carbon. The latter was suggested to be caused by changes in the adsorption properties of the unburned char and a decreased formation of soot, which was found to have a large AEA...

  20. Fluidized bed combustion of single coal char particles at high CO{sub 2} concentration

    Energy Technology Data Exchange (ETDEWEB)

    Scala, F.; Chirone, R. [CNR, Naples (Italy)

    2010-12-15

    Combustion of single coal char particles was studied at 850{sup o}C in a lab-scale fluidized bed at high CO{sub 2} concentration, typical of oxyfiring conditions. The burning rate of the particles was followed as a function of time by continuously measuring the outlet CO and O{sub 2} concentrations. Some preliminary evaluations on the significance of homogeneous CO oxidation in the reactor and of carbon gasification by CO{sub 2} in the char were also carried out. Results showed that the carbon burning rate increases with oxygen concentration and char particle size. The particle temperature is approximately equal to that of the bed up to an oxygen concentration of 2%, but it is considerably higher for larger oxygen concentrations. Both CO{sub 2} gasification of char and homogeneous CO oxidation are not negligible. The gasification reaction rate is slow and it is likely to be controlled by intrinsic kinetics. During purely gasification conditions the extent of carbon loss due to particle attrition by abrasion (estimated from the carbon mass balance) appears to be much more important than under combustion conditions.

  1. Investigation of the particle size distribution and particle density characteristics of Douglas fir hogged fuel fly ash collected under known combustion conditions. Technical Progress Report No. 2

    Energy Technology Data Exchange (ETDEWEB)

    Lang, A.J.; Junge, D.C.

    1978-12-01

    The increased interest in wood as a fuel source, coupled with the increasing demand to control the emission generated by wood combustion, has created a need for information characterizing the emissions that occur for given combustion conditions. This investigation characterizes the carbon char and inorganic fly ash size and density distribution for each of thirty-eight Douglas fir bark samples collected under known conditions of combustion.

  2. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    Energy Technology Data Exchange (ETDEWEB)

    Wei-Ping Pan; Yan Cao; John Smith

    2008-05-31

    On February 14, 2002, President Bush announced the Clear Skies Initiative, a legislative proposal to control the emissions of nitrogen oxides (NO{sub x}), sulfur dioxide (SO{sub 2}), and mercury from power plants. In response to this initiative, the National Energy Technology Laboratory organized a Combustion Technology University Alliance and hosted a Solid Fuel Combustion Technology Alliance Workshop. The workshop identified multi-pollutant control; improved sorbents and catalysts; mercury monitoring and capture; and improved understanding of the underlying reaction chemistry occurring during combustion as the most pressing research needs related to controlling environmental emissions from fossil-fueled power plants. The Environmental Control Technology Laboratory will help meet these challenges and offer solutions for problems associated with emissions from fossil-fueled power plants. The goal of this project was to develop the capability and technology database needed to support municipal, regional, and national electric power generating facilities to improve the efficiency of operation and solve operational and environmental problems. In order to effectively provide the scientific data and the methodologies required to address these issues, the project included the following aspects: (1) Establishing an Environmental Control Technology Laboratory using a laboratory-scale, simulated fluidized-bed combustion (FBC) system; (2) Designing, constructing, and operating a bench-scale (0.6 MW{sub th}), circulating fluidized-bed combustion (CFBC) system as the main component of the Environmental Control Technology Laboratory; (3) Developing a combustion technology for co-firing municipal solid waste (MSW), agricultural waste, and refuse-derived fuel (RDF) with high sulfur coals; (4) Developing a control strategy for gaseous emissions, including NO{sub x}, SO{sub 2}, organic compounds, and heavy metals; and (5) Developing new mercury capturing sorbents and new

  3. Mutagenicity in salmonella of nitro-organic compounds in extracts of fly ash of a fluidized-bed combustor

    International Nuclear Information System (INIS)

    Remsen, J.F.; Harris, W.R.

    1983-01-01

    The mutagenicity of a crude benzene/methanol extract of fly ash from an atmospheric fluidized-bed combustor was tested in Salmonella. Six strains were used including three which were mutants in a nitroreductase gene locus. The numbers of revertants from his- to his+ as a function of the amount of fly ash extracted were determined. The results showed that the major mutagens in the crude extract were nitro compounds from the fact that reversion rates in the nitro-reductase-deficient strains were significantly lower than in the parent strains from which they were derived. The responses of three parental strains, TA1538, TA98, and TA100, were quite similar, thus no conclusions could be made about frameshift versus base-substitution mutagens. No identification of specific nitro-organic compounds has been made

  4. Kinetics of pyrolysis and combustion of spherical wood particles in a fluidized bed

    International Nuclear Information System (INIS)

    Mazziotti di Celso, Giuseppe; Rapagnà, Sergio; Prisciandaro, Marina; Zanoelo, Everton Fernando

    2014-01-01

    Highlights: • H 2 , CO 2 , CO and CH 4 released during wood pyrolysis were experimentally monitored. • CO 2 formed by burning the residual tar/char mixture was experimentally determined. • The kinetics of species production was reproduced with two simplified models. • The increase of the bed reactor temperature statistically enhanced the gas yield. • The pyrolysis time is statistically reduced by decreasing the particle size. - Abstract: The kinetics of wood pyrolysis and combustion of residual fuel at different particle diameters and temperatures was investigated. A known mass of wooden spheres was fed at the top of a fluidized bed reactor filled with olivine particles and fluidized with nitrogen. The concentration of H 2 , CO 2 , CO and CH 4 was on-line monitored with gas analyzers. An irreversible first order reaction was applied to describe the biomass pyrolysis. The rate constant was dependent on the average temperature of wood particle, obtained by solving the transient one-dimensional problem of heat conduction in a sphere. The rate for an irreversible second order reaction between the residual fuel and oxygen at the fluid–solid interface, which takes a finite resistance to mass transfer into account, was adopted to describe the combustion. The semi-empirical kinetic models for pyrolysis and combustion were able to describe, with certain limitations inherent to model simplifications, the experimental transient results of molar flow rates of major released species. A statistical model based on the results of the factorial design of experiments (3 2 ) confirmed a statistical significant effect of temperature and wood particle diameter on the gas yield and time of pyrolysis, respectively

  5. Polycyclic aromatic hydrocarbons and organic matter associated to particulate matter emitted from atmospheric fluidized bed coal combustion

    International Nuclear Information System (INIS)

    Mastral, A.M.; Callen, M.S.; Garcia, T.

    1999-01-01

    The polycyclic aromatic hydrocarbons (PAH) and the organic matter (OM) content associated with particulate matter (PM) emissions from atmospheric fluidized bed coal combustion have been studied. The two main aims of the work have been (a) to study OM and PAH emissions as a function of the coal fluidized bed combustion (FBC) variables in solid phase and (b) to check if there is any correlation between OM and PAH contained in the PM. The combustion was carried out in a laboratory scale plant at different combustion conditions: temperature, percentage of oxygen excess, and total air flow. PAH associated on the particulate matter have been analyzed by fluorescence spectroscopy in the synchronous mode (FS) after PM extraction by sonication with dimethylformamide (DMF). It can be concluded that there is not a direct relationship between the OM content and the PAH supported in the PM emitted. In addition, neither PM or OM show dependence between themselves

  6. Co-combustion of coal and non-recyclable paper & plastic waste in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Boavida, D.; Abelha, P.; Gulyurtlu, I.; Cabrita, I. [DEECA-INETI, Lisbon (Portugal)

    2002-07-01

    Co-combustion of waste with coal was carried out using a fluidised bed combustor with the aim of achieving a fuel mixture with little variations in its heating value and simultaneously reducing the accumulation of non-toxic waste material by upgrading them for energy purposes. Results obtained indicate that the feeding of waste materials could present serious problems which could render conditions for a stable combustion difficult to achieve. The waste was fed mixed with coal and there was some difference observed in results regarding the combustion efficiency and emissions. Part of the combustion of waste material, contrary to that of coal, was observed to take place in the freeboard where the temperature was as much as 150{degree}C above that of the bed. 6 refs., 8 figs., 8 tabs.

  7. Ash Deposit Formation and Deposit Properties. A Comprehensive Summary of Research Conducted at Sandia's Combustion Research Facility

    Energy Technology Data Exchange (ETDEWEB)

    Larry L. Baxter

    2000-08-01

    This report summarizes experimental and theoretical work performed at Sandia's Combustion Research Facility over the past eight years on the fate of inorganic material during coal combustion. This work has been done under four broad categories: coal characterization, fly ash formation, ash deposition, and deposit property development. The objective was to provide sufficient understanding of these four areas to be able to predict coal behavior in current and advanced conversion systems. This work has led to new characterization techniques for fuels that provide, for the first time, systematic and species specific information regarding the inorganic material. The transformations of inorganic material during combustion can be described in terms of the net effects of the transformations of these individual species. Deposit formation mechanisms provide a framework for predicting deposition rates for abroad range of particle sizes. Predictions based on these rates many times are quite accurate although there are important exceptions. A rigorous framework for evaluating deposit has been established. Substantial data have been obtained with which to exercise this framework, but this portion of the work is less mature than is any other. Accurate prediction of deposit properties as functions of fuel properties, boiler design, and boiler operating conditions represents the single most critical area where additional research is needed.

  8. Differential pulmonary inflammation and in vitro cytotoxicity of size-fractionated fly ash particles from pulverized coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    M. Ian Gilmour; Silvia O' Connor; Colin A.J. Dick; C. Andrew Miller; William P. Linak [U.S. Environmental Protection Agency, Research Triangle Park, NC (United States). National Health and Environmental Effects Research Laboratory

    2004-03-01

    Exposure to airborne particulate matter (PM) has been associated with adverse health effects in humans. Pulmonary inflammatory responses were examined in CD1 mice after intratracheal instillation of 25 or 100 {mu}g of ultrafine ({lt}0.2 {mu}m), fine ({lt}2.5 {mu}m), and coarse ({gt}2.5 {mu}m) coal fly ash from a combusted Montana subbituminous coal, and of fine and coarse fractions from a combusted western Kentucky bituminous coal. After 18 hr, the lungs were lavaged and the bronchoalveolar fluid was assessed for cellular influx, biochemical markers, and pro-inflammatory cytokines. The responses were compared with saline and endotoxin as negative and positive controls, respectively. On an equal mass basis, the ultrafine particles from combusted Montana coal induced a higher degree of neutrophil inflammation and cytokine levels than did the fine or coarse PM. The western Kentucky fine PM caused a moderate degree of inflammation and protein levels in bronchoalveolar fluid that were higher than the Montana fine PM. Coarse PM did not produce any significant effects. In vitro experiments with rat alveolar macrophages showed that of the particles tested, only the Montana ultrafine displayed significant cytotoxicity. It is concluded that fly ash toxicity is inversely related with particle size and is associated with increased sulfur and trace element content. 42 refs., 5 figs., 3 tabs.

  9. High plant availability of phosphorus and low availability of cadmium in four biomass combustion ashes

    DEFF Research Database (Denmark)

    Li, Xiaoxi; Rubæk, Gitte Holton; Sørensen, Peter

    2016-01-01

    and ash significantly increased crop yields and P uptake on the P-depleted soil. In contrast, on the adequate-P soil, the barley yield showed little response to soil amendment, even at 300–500 kg P ha− 1 application, although the barley took up more P at higher applications. The apparent P use efficiency...... of the additive was 20% in ryegrass - much higher than that of barley for which P use efficiencies varied on the two soils. Generally, crop Cd concentrations were little affected by the increasing and high applications of ash, except for relatively high Cd concentrations in barley after applying 25 Mg ha− 1 straw...... ash. Contrarily, even modest increases in the TSP application markedly increased Cd uptake in plants. This might be explained by the low Cd solubility in the ash or by the reduced Cd availability due to the liming effect of ash. High concentrations of resin-extractable P (available P) in the ash...

  10. Oxygen Carrier Aided Combustion (OCAC of Wood Chips in a Semi-Commercial Circulating Fluidized Bed Boiler Using Manganese Ore as Bed Material

    Directory of Open Access Journals (Sweden)

    Magnus Rydén

    2016-11-01

    Full Text Available Oxygen Carrier Aided Combustion (OCAC is realized by using an active oxygen-carrying bed material in fluidized bed boilers. The active material is reduced in fuel rich parts of the boiler and oxidized in air rich parts. Advantages could be achieved such as new mechanisms for oxygen transport in space and time. Here calcined manganese ore has been used as active bed material in a 12 MWth circulating fluidized bed boiler. The fuel was wood chips and the campaign lasted more than two weeks. From an operational point of view, manganese ore worked excellently. From the temperature profile of the boiler it can be concluded that fuel conversion was facilitated, especially in the dense bottom bed. The effect did not always translate to reduced emissions, which suggests that final combustion in the cyclone outlet was also influenced. Substituting 10% of the sand bed with manganese ore made it possible to reduce the air to fuel ratio without generating large amounts of CO. The use of 100% manganese ore resulted in higher emissions of CO than the sand reference, but, when combined sulphur feeding, dramatic reductions in CO emissions, up to 90% compared to sand reference, was achieved.

  11. Chemical signature of two Permian volcanic ash deposits within a bentonite bed from Melo, Uruguay

    Directory of Open Access Journals (Sweden)

    Liane M. Calarge

    2006-09-01

    Full Text Available A Permian bentonite deposit at Melo, Uruguay is composed of a calcite-cemented sandstone containing clay pseudomorphs of glass shards (0-0.50 m overlying a pink massive clay deposit (0.50-2.10m. The massive bed is composed of two layers containing quartz and smectite or pure smectite respectively. The smectite is remarkably homogeneous throughout the profile: it is a complex mixed layer composed of three layer types whose expandability with ethylene glycol (2EG 1EG or 0EG sheets in the interlayer zone which correspond to low-, medium- and high-charge layers respectively varies with the cation saturating the interlayer zone. The smectite homogeneity through the profile is the signature of an early alteration process in a lagoonal water which was over saturated with respect to calcite. Compaction during burial has made the bentonite bed a K-depleted closed system in which diagenetic illitization was inhibited. Variations in major, REE and minor element abundances throughout the massive clay deposit suggest that it originated from two successive ash falls. The incompatible element abundances are consistent with that of a volcanic glass fractionated from a rhyolite magma formed in a subduction/collision geological context.Um depósito Permiano de bentonita em Melo, Uruguai,é composto por um arenito com cimento calcítico contendo pseudomorfos de argila sobre detritos vítreos(0-0.50 m superpostos a um deposito maciço de argila rosado (0.50-2.10 m. A camada maciça é composta por dois níveis contendo quartzo e esmectita ou esmectita pura, respectivamente. A homogeneidade de esmectita ao longo do perfil é notável: trata-se de um interestratificado composto de três tipos de camadas, cuja expansibilidade com etileno-glicol (folhas 2EG, 1EG ou 0EG na zona interfoliar correspondentes a camadas com baixa, média e alta carga, respectivamente variam com o tipo de cátion que satura a zona interfoliar. A homogeneidade da esmectita ao longo do perfil

  12. Release of alkali salts and coal volatiles affecting internal components in fluidized bed combustion systems

    Directory of Open Access Journals (Sweden)

    Arias del Campo, E.

    2003-12-01

    Full Text Available In spite of the potential advantages of atmospheric fluidized bed systems, experience has proved that, under certain environments and operating conditions, a given material employed for internal components could lead to catastrophic events. In this study, an attempt is made to establish material selection and operational criteria that optimize performance and availability based on theoretical considerations of the bed hydrodynamics, thermodynamics and combustion process. The theoretical results may indicate that, for high-volatile coals with particle diameters (dc of 1-3 mm and sand particle size (ds of 0.674 mm, a considerable proportion of alkali chlorides may be transferred into the freeboard region of fluidized bed combustors as vapor phase, at bed temperatures (Tb < 840 °C, excess air (XSA ≤ 20 %, static bed height (Hs ≤ 0.2 m and fluidizing velocity (Uo < 1 m/s. Under these operating conditions, a high alkali deposition may be expected to occur in heat exchange tubes located above the bed. Conversely, when the combustors operate at Tb > 890 °C and XSA > 30 %, a high oxidation rate of the in-bed tubes may be present. Nevertheless, for these higher Tb values and XSA < 10 %, corrosion attack of metallic components, via sulfidation, would occur since the excessive gas-phase combustion within the bed induced a local oxygen depletion.

    A pesar de las ventajas potenciales de los sistemas atmosféricos de lecho fluidizado, la experiencia ha demostrado que, bajo ciertas atmósferas y condiciones de operación, un material que se emplea como componente interno podría experimentar una falla y conducir a eventos catastróficos. En este estudio, se intenta establecer un criterio tanto operativo como de selección del material que permita optimizar su disponibilidad y funcionalidad basados en consideraciones teóricas de la hidrodinámica del lecho, la termodin

  13. Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

    Data.gov (United States)

    U.S. Environmental Protection Agency — Pulverized bituminous coal was burned in a 10W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28,...

  14. Biosecurity on Poultry Farms from On-Farm Fluidized Bed Combustion and Energy Recovery from Poultry Litter

    Directory of Open Access Journals (Sweden)

    Kevin McDonnell

    2010-07-01

    Full Text Available The spreading of poultry litter in recent years has led to a serious increase in levels of eutrophication, nitrate leaching, high Biological Oxygen Demand (BOD, ammonia toxicity, high chlorine concentrations and pathogen contamination. The review presented here details the optimum standards that should be met when storing litter for On-Farm Fluidized Bed Combustion. Storage conditions are paramount to a fuel combusting to its highest possible potential. Safety measures such as the prevention of leaching and spontaneous combustion must be adhered to, so too should the prevention and containment of possible diseases and pathogens to minimize the effects of contamination.

  15. Chemical characterization of bottom ashes generated during combustion of a Colombian mineral coal in a thermal power plant

    International Nuclear Information System (INIS)

    Pinheiro, H.S.; Nogueira, R.E.F.Q.; Lobo, C.J.S.; Nobre, A.I.S.; Sales, J.C.; Silva, C.J.M.

    2012-01-01

    Bottom ashes generated during combustion of a mineral coal from Colombia were characterized by X-ray fluorescence spectrometry and X-ray diffraction. The interest in this particular coal is due to the fact that it will be used by a thermal power plant in Ceara, Northeastern Brazil, where it could produce over 900 tons of different residues/combustion products every day. Results from Xray fluorescence allowed identification and quantification of elements present in the sample: silicon (59,17%), aluminum (13,17%), iron (10,74%), potassium (6,11%), titanium (2,91%), calcium (4,97%), sulphur (0,84%) and others (2,09%). The X-ray diffraction revealed patterns from silica, mullite, calcium sulphate and hydrated sodium. Results obtained so far indicate that the material is a potential raw-material for use in the formulation of ceramic components (author)

  16. Properties of ash generated during sewage sludge combustion: A multifaceted analysis

    International Nuclear Information System (INIS)

    Magdziarz, Aneta; Wilk, Małgorzata; Gajek, Marcin; Nowak-Woźny, Dorota; Kopia, Agnieszka; Kalemba-Rec, Izabela; Koziński, Janusz A.

    2016-01-01

    This paper presents chemical properties of sewage sludge ashes required for determining their thermal characteristics. A novel approach, linking selected advanced analytical techniques with FactSage modelling, was developed and applied to obtain new information on deposit formation mechanisms that contribute to fouling and slagging. The mineral matter and fusion temperatures were investigated using a variety of analytical techniques including XRF, ICP-MS, XRD, SEM-EDX and AFT. The slagging and fouling indices were calculated and the sintering properties were predicted. The studied ashes were rich in P_2O_5, CaO, SiO_2 and Fe_2O_3, but their concentrations slightly differed. Phase analyses suggested the existence of calcium and phosphorus as main phases. Thermal behaviour of ashes was studied focusing on the mass loss, temperature peaks and thermic effects with the increasing of temperature up to 1200 °C under air atmosphere. The changes in concentration of ash compounds contributed to differences in ash fusion temperatures. FactSage thermochemical equilibrium calculations were used to predict the amount of liquid slag and solid phases, giving information about slagging properties of ashes. The general conclusion based on experimental studies is that sewage sludge ashes cause the slagging and fouling hazard while they reveal low corrosive effect. - Highlights: • Characterisation of sewage sludge ashes were given. • Transformation of inorganic components was determined using XRD and FTIR. • The ash fusion behaviour of ashes was studied experimentally. • Empirical indices were calculated indicating slagging and fouling propensities. • Thermodynamic equilibrium calculation was used.

  17. Analysis of microalgae pellets combustion in a circulating fluidized-bed

    Directory of Open Access Journals (Sweden)

    Kosowska-Golachowska Monika

    2017-01-01

    Full Text Available Microalgae are expected to become an important source of highvalue products with several applications in a large number of areas of biotechnology and, especially, in biofuels production. The increasing interest in microalgae as a source of biofuel (so-called third generation biofuel is due to the several advantages. The objective of this study was to investigate combustion characteristics of microalgae (Oscillatoria sp. pellets burnt in a circulating fluidized-bed (CFB in terms of sample temperature profiles, ignition time, ignition temperature, devolatilization time and the burnout time. Spherical 10-mm microalgae pellets were tested at temperature of 850°C in a 12-kW bench-scale CFB combustor.

  18. The French example: nuclear energy, fluidized bed combustion, gas treating against SO2 pollution

    International Nuclear Information System (INIS)

    Leygonie, R.; Bouscaren, R.

    1989-01-01

    Sulphur dioxide emissions in France have declined by 64% from 1980 to 1987. Those of nitrogen oxides from stationary sources have been lowered by 49 %. The main reason is the development of nuclear electricity, from 52 000 TJ in 1977 to 894 000 TJ in 1987. Another factor is a better efficiency in energy use: from 1973 to 1987, the Gross Domestic Product has progressed by 33% while energy consumption only increased by 6.7%. Furthermore, natural gas consumption has grown from 360 000 TJ in 1973 up to 878 000 TJ in 1987. France still must abate emissions in the medium and long range, and efforts will essentially bear on small and medium-size combustion plants by direct injection of limestone and lime in the furnace development of various types of desulfurizing fluid bed combustors and flue gas treatment processes [fr

  19. Investigation on catalytic gasification of high-ash coal with mixing-gas in a small-scale fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.; Zhang, J.; Lin, J. [Fuzhou University, Fuzhou (China)

    2005-10-15

    The experimental study on the Yangquan high-ash coal catalytic gasification with mixing gas by using solid alkali or waste liquid of viscose fiber as the catalyst in a small-scale fluidized bed with 28 mm i.d. was carried out. The loading saturation levels of two catalysts in Yangquan high-ash coal are about 6%. Under the gasification temperature ranging from 830 to 900{sup o}C and from 900 to 920{sup o}C, the apparent reaction order of Yangquan high-ash coal with respect to the unreacted carbon fraction approximates to 2.3 and 1/3 for the non-catalyst case, respectively. Also, the different values of apparent reaction order in the two temperature ranges are presented for the case with 3% solid alkali catalyst loaded. At the low temperature ranging from 830 to 860{sup o}C, the apparent reaction order of catalytic gasification is 1 since enough active carbon sites on the coal surface are formed during the catalytic gasification by solid alkali. But at the high temperature ranging from 860 to 920{sup o}C, the sodium carbonate produced by the reaction of solid alkali with carbon dioxide can be easily fused, transferred and re-distributed, which affects the gasification reaction rate, and the apparent reaction order of catalytic gasification is reduced to 1.3. 10 refs., 9 figs., 4 tab s.

  20. Volcanic ash deposition, eelgrass beds, and inshore habitat loss from the 1920s to the 1990s at Chignik, Alaska

    Science.gov (United States)

    Zimmermann, Mark; Ruggerone, Gregory T.; Freymueller, Jeffrey T.; Kinsman, Nicole; Ward, David H.; Hogrefe, Kyle R.

    2018-03-01

    We quantified the shallowing of the seafloor in five of six bays examined in the Chignik region of the Alaska Peninsula, confirming National Ocean Service observations that 1990s hydrographic surveys were shallower than previous surveys from the 1920s. Castle Bay, Chignik Lagoon, Hook Bay, Kujulik Bay and Mud Bay lost volume as calculated from Mean Lower Low Water (Chart Datum) to the deepest depths and four of these sites lost volume from Mean High Water to the deepest depths. Calculations relative to each datum were made because tidal datum records exhibited an increase in tidal range in this region from the 1920s to the 1990s. Our analysis showed that Mud Bay is quickly disappearing while Chignik Lagoon is being reduced to narrow channels. Anchorage Bay was the only site that increased in depth over time, perhaps due to erosion. Volcanoes dominate the landscape of the Chignik area. They have blanketed the region in deep ash deposits before the time frame of this study, and some have had smaller ash-producing eruptions during the time frame of this study. Remobilization of land-deposited ash and redeposition in marine areas - in some locations facilitated by extensive eelgrass (Zostera marina) beds (covering 54% of Chignik Lagoon and 68% of Mud Bay in 2010) - is the most likely cause of shallowing in the marine environment. Loss of shallow water marine habitat may alter future abundance and distribution of several fish, invertebrate and avian species.

  1. Sulphation of calcium-based sorbents in circulating fluidised beds under oxy-fuel combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Francisco Garcia-Labiano; Luis F. de Diego; Alberto Abad; Pilar Gayan; Margarita de las Obras-Loscertales; Aranzazu Rufas; Juan Adanez [Instituto de Carboquimica (CSIC), Zaragoza (Spain). Dept. Energy and Environment

    2009-07-01

    Sulphur Retention (SR) by calcium-based sorbents is a process highly dependent on the temperature and CO{sub 2} concentration. In circulating fluidised beds combustors (CFBC's) operating under oxy-fuel conditions, the sulphation process takes place in atmospheres enriched in CO{sub 2} with bed concentrations that can vary from 40 to 95%. Under so high CO{sub 2} concentrations, very different from that in conventional coal combustion atmosphere with air, the calcination and sulphation behaviour of the sorbent must be defined to optimise the SR process in the combustor. The objective of this work was to determine the SO{sub 2} retention capacity of a Spanish limestone at typical oxy-fuel conditions in CFBC's. Long term duration tests of sulphation (up to 24 h), to simulate the residence time of sorbents in CFBC's, were carried out by thermogravimetric analysis (TGA). Clear behaviour differences were found under calcining and non-calcining conditions. Especially relevant was the result obtained at calcining conditions but close to the thermodynamic temperature given for sorbent calcination. This situation must be avoided in CFBC's because the CO{sub 2} produced inside the particle during calcination can destroy the particles if a non-porous sulphate product layer has been formed around the particle. The effect of the main variables on the sorbent sulphation such as SO{sub 2} concentration, temperature, and particle size were analysed in the long term TGA tests. These data were also used to determine the kinetic parameters for the sulphation under oxy-fuel combustion conditions, which were able to adequately predict the sulphation conversion values in a wide range of operating conditions. 20 refs., 5 figs., 2 tabs.

  2. Modelling of Effects of Operating Conditions and Coal Reactivity on Temperature of Burning Particles in Fluidized Bed Combustion

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Karel; Hartman, Miloslav; Pohořelý, Michael; Trnka, Otakar

    2004-01-01

    Roč. 1, č. 2 (2004), s. 261-274 ISSN 1211-1910 R&D Projects: GA AV ČR IAA4072201; GA AV ČR IAA4072001 Institutional research plan: CEZ:AV0Z4072921 Keywords : fluidized bed combustion * char temperature * modelling Subject RIV: DI - Air Pollution ; Quality

  3. Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

    KAUST Repository

    Zhao, Zhenlong; Chen, Tianjiao; Ghoniem, Ahmed F.

    2013-01-01

    Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two

  4. Reduction of SO sub 2 emission from a fluidized-bed under staged combustion by coarse limestone

    International Nuclear Information System (INIS)

    Khan, W.Z.; Gibbbs, B.M.

    1998-01-01

    A study was performed to investigate the effect of course limestone on the reduction of SO sub 2 emission from a fluidized-bed under staged combustion. The limestone of 1.2-2.5 mm size was premixed with fine coal of 1-3 mm size and fed under bed. The staging levels, bed height, and Ca/S ratio was fixed at 70:30, 30 cm and 3:1, respectively. A maximum of around 50% reduction in SO sub 2 emissions was achieved at both excess air of 20 and 40% and at 830 deg. C. bed temperature. The SO sub 2 emissions were very sensitive to bed temperature. The course limestone was found better in desulfurization efficiency at lower temperature than fine limestone. (author)

  5. Corrosivity of hot flue gases in the fluidized bed combustion of recovered waste wood

    Energy Technology Data Exchange (ETDEWEB)

    Enestam, S.

    2011-07-01

    In recent years, recovered waste wood has become a fuel of interest due to its green energy benefits and low price compared to virgin wood-based fuels. However, waste wood is often contaminated with paint, plastic, and metal components, producing concentrations of heavy metals such as zinc and lead, chlorine, sodium, and sometimes sulphur that are elevated relative to those in virgin wood. In several cases, boilers burning waste wood have experienced increased fouling and corrosion of furnace walls, superheaters, and economizers, problems associated with chlorine, zinc, lead, and alkali metals in the deposits. The location of the deposits and the corrosion as well as the composition of the deposits vary with the fuel composition, boiler design, combustion parameters, flue gas temperature, and material temperature. Experience gained from the operation of biofuel and waste boilers shows that corrosion damage can be reduced, or even avoided, by the selection of optimum materials or for heat exchanger surfaces, by the use of fuel mixtures or additives that decrease the corrosivity of the combustion environment, by the placement of superheaters in a less corrosive environment, and by adjusting the steam parameters. Finding the right solutions for boilers burning RWW requires a thorough understanding of the whole process, including the fuel fed into the boiler, the combustion atmosphere, the corrosivity of the flue gas and the deposits, and the corrosion resistance of different boiler materials under the prevailing conditions. The objective of this work was to shed more light on the combustion environment in bubbling fluidized bed boilers burning RWW and thus increase knowledge about the corrosivity of zinc- and lead-rich deposits formed during the combustion of RWW, with the final goal of developing a corrosion prediction tool for use in the design of boilers for RWW combustion. With such a tool, it would be possible to optimize boiler design and material selection with

  6. Studies on nitrogen oxides (NOx and N2O) in pressurized fluidized bed combustion

    International Nuclear Information System (INIS)

    Lu Yong

    1998-01-01

    This thesis describes the experimental studies of nitrogen oxide (NO, NO 2 , N 2 O) emissions in pressurized fluidized bed combustion (PFBC). In the first part of the thesis the background and the objectives of this study are introduced. The second part summarizes the fundamental knowledge about the formation and destruction of nitrogen oxides in coal combustion, particularly in the conditions of PFBC. The instrumentation of test facilities, measurement and data analysis is described in the third part. Then the most important experimental results follow in the next parts. The forth part describes the results from a PFBC test rig and an empirical modelling for predicting the emissions of NO x and N 2 O. Finally, the fundamental work on coal combustion and fuel nitrogen conversion in a PFBC batch reactor is presented. These studies clearly confirm the potential of PFBC technology in the control nitrogen of oxide emissions. The research in the test rig was concentrated on determining the effects of process parameters on the emissions of nitrogen oxides with different fuels. Another objective was to examine the reduction of nitrogen oxides with the control methods in PFBC conditions, including ammonia injection and air staging combustion for reducing NO, and high temperature operations for reducing N 2 0. The results indicate that pressurized operation suppresses the conversion of fuel-N to nitrogen oxides and favors with employing the reduction methods for further nitrogen oxide reduction, for instance the temperature window of NO reduction with ammonia injection has been found to be widened to even lower temperature range. Maximum reductions of 80-85 % with ammonia injection and 75-80 % with air staging combustion were achieved in the conditions examined. Considerably low emissions of N 2 O ( 2 O control, and thermal decomposition proved to be the laming pathway of N 2 O destruction in PFBC. In the examined pressure range, increasing pressure causes a decrease of NO

  7. Characteristics modeling for supercritical circulating fluidized bed boiler working in oxy-combustion technology

    Directory of Open Access Journals (Sweden)

    Balicki Adrian

    2014-06-01

    Full Text Available Among the technologies which allow to reduce greenhouse gas emission, mainly carbon dioxide, special attention deserves the idea of ‘zeroemission’ technology based on boilers working in oxy-combustion technology. In the paper the results of analyses of the influence of changing two quantities, namely oxygen share in oxidant produced in the air separation unit, and oxygen share in oxidant supplied to the furnace chamber on the selected characteristics of a steam boiler including the degree of exhaust gas recirculation, boiler efficiency and adiabatic flame temperature, was examined. Due to the possibility of the integration of boiler model with carbon dioxide capture, separation and storage installation, the subject of the analysis was also to determine composition of the flue gas at the outlet of a moisture condensation installation. Required calculations were made using a model of a supercritical circulating fluidized bed boiler working in oxy-combustion technology, which was built in a commercial software and in-house codes.

  8. Combustion of palm kernel shell in a fluidized bed: Optimization of biomass particle size and operating conditions

    International Nuclear Information System (INIS)

    Ninduangdee, Pichet; Kuprianov, Vladimir I.

    2014-01-01

    Highlights: • Safe burning of palm kernel shell is achievable in a FBC using alumina as the bed material. • Thermogravimetric analysis of the shell with different particle sizes is performed. • Optimal values of the shell particle size and excess air lead to the minimum emission costs. • Combustion efficiency of 99.4–99.7% is achievable when operated under optimal conditions. • CO and NO emissions of the FBC are at levels substantially below national emission limits. - Abstract: This work presents a study on the combustion of palm kernel shell (PKS) in a conical fluidized-bed combustor (FBC) using alumina sand as the bed material to prevent bed agglomeration. Prior to combustion experiments, a thermogravimetric analysis was performed in nitrogen and dry air to investigate the effects of biomass particle size on thermal and combustion reactivity of PKS. During the combustion tests, the biomass with different mean particle sizes (1.5 mm, 4.5 mm, 7.5 mm, and 10.5 mm) was burned at a 45 kg/h feed rate, while excess air was varied from 20% to 80%. Temperature and gas concentrations (O 2 , CO, C x H y as CH 4 , and NO) were recorded along the axial direction in the reactor as well as at stack. The experimental results indicated that the biomass particle size and excess air had substantial effects on the behavior of gaseous pollutants (CO, C x H y , and NO) in different regions inside the reactor, as well as on combustion efficiency and emissions of the conical FBC. The CO and C x H y emissions can be effectively controlled by decreasing the feedstock particle size and/or increasing excess air, whereas the NO emission can be mitigated using coarser biomass particles and/or lower excess air. A cost-based approach was applied to determine the optimal values of biomass particle size and excess air, ensuring minimum emission costs of burning the biomass in the proposed combustor. From the optimization analysis, the best combustion and emission performance of the

  9. The reaction of acid mine drainage with fly ash from coal combustion

    International Nuclear Information System (INIS)

    Kim, A.G.

    1999-01-01

    The placement of alkaline fly ash in abandoned, reclaimed or active surface coal mines is intended to reduce the amount of acid mine drainage (AMD) produced at such sites by neutralization, inhibition of acid forming bacteria, encapsulation of the pyrite or water diversion. A continuing concern with this application is the potential release of trace elements from the fly ash when it is placed in contact with AMD. To investigate the possible release of antimony, arsenic, barium, boron, cadmium, chromium, cobalt, copper, lead, nickel, selenium, and zinc from fly ash, a series of column leaching tests were conducted. A one kg fly ash sample, placed in a 5-cm by 1 m acrylic columns, was leached at a nominal rate of 250 mL/d for between 30 and 60 days. The leachant solutions were deionized water, and dilute solutions of sulfuric acid and ferric chloride. Leaching tests have been completed on 28 fly ash samples. leachate data, analyzed as the mass extracted with respect to the concentration in the solid, indicate that the release of trace elements is variable, with only barium and zinc extracted at greater than 50 pct of the amount present in the original sample. As a comparison, water quality changes have been monitored at three sites where fly ash grout was injected after reclamation to control AMD. When compared before and after grouting, small increases in pH and decreases in acidity at discharge points were observed. Concentrations of trace metals were found to be comparable in treated and untreated areas. When grouted and ungrouted areas were compared, the effect of the fly ash was shown to be localized in the areas of injection. These studies indicated that when fly ash is used as a reagent to control of AMD, the release of trace elements is relatively small

  10. Artificial intelligence-based modeling and control of fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ikonen, E.; Leppaekoski, K. (Univ. of Oulu, Dept. of Process and Environmental Engineering (Finland)). email: enso.ikonen@oulu.fi

    2009-07-01

    AI-inspired techniques have a lot to offer when developing methods for advanced identification, monitoring, control and optimization of industrial processes, such as power plants. Advanced control methods have been extensively examined in the research of the Power Plant Automation group at the Systems Engineering Laboratory, e.g., in fuel inventory modelling, combustion power control, modelling and control of flue gas oxygen, drum control, modelling and control of superheaters, or in optimization of flue-gas emissions. Most engineering approaches to artificial intelligence (AI) are characterized by two fundamental properties: the ability to learn from various sources and the ability to deal with plant complexity. Learning systems that are able to operate in uncertain environments based on incomplete information are commonly referred to as being intelligent. A number of other approaches exist, characterized by these properties, but not easily categorized as AI-systems. Advanced control methods (adaptive, predictive, multivariable, robust, etc.) are based on the availability of a model of the process to be controlled. Hence identification of processes becomes a key issue, leading to the use of adaptation and learning techniques. A typical learning control system concerns a selection of learning techniques applied for updating a process model, which in turn is used for the controller design. When design of learning control systems is complemented with concerns for dealing with uncertainties or vaguenesses in models, measurements, or even objectives, particularly close connections exist between advanced process control and methods of artificial intelligence and machine learning. Needs for advanced techniques are typically characterized by the desire to properly handle plant non-linearities, the multivariable nature of the dynamic problems, and the necessity to adapt to changing plant conditions. In the field of fluidized bed combustion (FBC) control, the many promising

  11. Cadmium adsorption by coal combustion ashes-based sorbents-Relationship between sorbent properties and adsorption capacity

    Energy Technology Data Exchange (ETDEWEB)

    Balsamo, Marco; Di Natale, Francesco; Erto, Alessandro; Lancia, Amedeo [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Montagnaro, Fabio, E-mail: fabio.montagnaro@unina.it [Dipartimento di Chimica, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant' Angelo, 80126 Napoli (Italy); Santoro, Luciano [Dipartimento di Chimica, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant' Angelo, 80126 Napoli (Italy)

    2011-03-15

    A very interesting possibility of coal combustion ashes reutilization is their use as adsorbent materials, that can also take advantage from proper beneficiation techniques. In this work, adsorption of cadmium from aqueous solutions was taken into consideration, with the emphasis on the intertwining among waste properties, beneficiation treatments, properties of the beneficiated materials and adsorption capacity. The characterization of three solid materials used as cadmium sorbents (as-received ash, ash sieved through a 25 {mu}m-size sieve and demineralized ash) was carried out by chemical analysis, infrared spectroscopy, laser granulometry and mercury porosimetry. Cadmium adsorption thermodynamic and kinetic tests were conducted at room temperature, and test solutions were analyzed by atomic absorption spectrophotometry. Maximum specific adsorption capacities resulted in the range 0.5-4.3 mg g{sup -1}. Different existing models were critically considered to find out an interpretation of the controlling mechanism for adsorption kinetics. In particular, it was observed that for lower surface coverage the adsorption rate is governed by a linear driving force while, once surface coverage becomes significant, mechanisms such as the intraparticle micropore diffusion may come into play. Moreover, it was shown that both external fluid-to-particle mass transfer and macropore diffusion hardly affect the adsorption process, which was instead regulated by intraparticle micropore diffusion: characteristic times for this process ranged from 4.1 to 6.1 d, and were fully consistent with the experimentally observed equilibrium times. Results were discussed in terms of the relationship among properties of beneficiated materials and cadmium adsorption capacity. Results shed light on interesting correlations among solid properties, cadmium capture rate and maximum cadmium uptake.

  12. Chemical Looping Combustion of Hematite Ore with Methane and Steam in a Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Samuel Bayham

    2017-08-01

    Full Text Available Chemical looping combustion is considered an indirect method of oxidizing a carbonaceous fuel, utilizing a metal oxide oxygen carrier to provide oxygen to the fuel. The advantage is the significantly reduced energy penalty for separating out the CO2 for reuse or sequestration in a carbon-constrained world. One of the major issues with chemical looping combustion is the cost of the oxygen carrier. Hematite ore is a proposed oxygen carrier due to its high strength and resistance to mechanical attrition, but its reactivity is rather poor compared to tailored oxygen carriers. This problem is further exacerbated by methane cracking, the subsequent deposition of carbon and the inability to transfer oxygen at a sufficient rate from the core of the particle to the surface for fuel conversion to CO2. Oxygen needs to be readily available at the surface to prevent methane cracking. The purpose of this work was to demonstrate the use of steam to overcome this issue and improve the conversion of the natural gas to CO2, as well as to provide data for computational fluid dynamics (CFD validation. The steam will gasify the deposited carbon to promote the methane conversion. This work studies the performance of hematite ore with methane and steam mixtures in a 5 cm fluidized bed up to approximately 140 kPa. Results show an increased conversion of methane in the presence of steam (from 20–45% without steam to 60–95% up to a certain point, where performance decreases. Adding steam allows the methane conversion to carbon dioxide to be similar to the overall methane conversion; it also helped to prevent carbon accumulation from occurring on the particle. In general, the addition of steam to the feed gas increased the methane conversion. Furthermore, the addition of steam caused the steam methane reforming reaction to form more hydrogen and carbon monoxide at higher steam and methane concentrations, which was not completely converted at higher concentrations and

  13. Study of the chemistry of sulfur- and nitrogen oxides at fluidized bed combustion. Final report

    International Nuclear Information System (INIS)

    Lindqvist, O.

    1995-01-01

    Research has been carried out concerning chemistry of nitrogen and sulfur oxides, with relevance to fluidized bed combustion. Studies of the heterogeneous decomposition reactions of NO and N 2 O molecules have also been carried out. The effect of O 2 on the heterogeneous reactions has been investigated and the results indicate that NO can deteriorate only in the reducing zones of a FBC. The formation of NO and N 2 O as well as the question of what parameters affect this formation have been studied in a series of combustion experiments. In addition, it has also been demonstrated that the volatiles and the char are about equally important for the NO and N 2 O formation. Quantum chemical calculations have been used to study the surface processes of the nitrogen oxides. Investigations of the desulfurization reactions at high percentages of CO 2 with special regard to the PFBC technique have been made. In addition, the same reaction has been studied with e.g. spectroscopic methods at normal CO 2 percentages, but with varying amounts of O 2 and CO. CaSO 3 has been demonstrated to be an intermediary and CaS as being one of the products. An important part of the project activities is the analytical work which primarily supports the full scale experiments on the 12 MW th CTH FBC boiler. As a link between the CTH boiler and our analytical laboratory, a chemical engineer also has been employed. In this activity is also included the development of sampling and analytical methods, e.g. NH 3 and HCN sampling in the combustor. Time has also been allocated to measuring corrosive alkali metals (Na and K) in flue gases from a PFBC plant. 29 refs, 4 figs, 1 tab

  14. Making the most of South Africa’s low-quality coal: Converting high-ash coal to fuel gas using bubbling fluidised bed gasifiers

    CSIR Research Space (South Africa)

    Engelbrecht, AD

    2010-08-31

    Full Text Available for process heating or for power generation using the IGCC (Integrated Gasification Combined Cycle) process. A high-ash coal from the Waterberg coalfield was tested in a bubbling fluidised bed gasifier using various gasification agents and operating conditions...

  15. Co-combustion of pulverized coal and solid recovered fuel in an entrained flow reactor- General combustion and ash behavior

    DEFF Research Database (Denmark)

    Wu, Hao; Glarborg, Peter; Frandsen, Flemming

    2011-01-01

    .9 wt.%, 14.8 wt.% and 25 wt.%, respectively. The effect of additives was evaluated by maintaining the share of secondary fuel (mixture of SRF and additive) at 14.8 wt.%. The experimental results showed that the fuel burnout, NO and SO2 emission in co-combustion of coal and SRF were decreased...... with increasing share of SRF. The majority of the additives inhibited the burnout, except for NaCl which seemed to have a promoting effect. The impact of additives on NO emission was mostly insignificant, except for ammonium sulphate which greatly reduced the NO emission. For SO2 emission, it was found that all...

  16. Flue gas desulfurization under simulated oxyfiring fluidized bed combustion conditions: The influence of limestone attrition and fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Scala, F.; Salatino, P. [CNR, Naples (Italy)

    2010-01-01

    Flue gas desulfurization by means of limestone injection under simulated fluidized bed oxyfiring conditions was investigated, with a particular focus on particle attrition and fragmentation phenomena. An experimental protocol was applied, based on the use of complementary techniques that had been previously developed for the characterization of attrition of sorbents in air-blown atmospheric fluidized bed combustors. The extent and pattern of limestone attrition by surface wear in the dense phase of a fluidized bed were assessed in bench scale fluidized bed experiments under simulated oxyfiring conditions. Sorbent samples generated during the oxyfiring tests were further characterized from the standpoint of fragmentation upon high velocity impact by means of a particle impactor. The experimental results were compared with those previously obtained with the same limestone under air-blown atmospheric fluidized bed combustion conditions. The profound differences in the attrition and fragmentation extents and patterns associated with oxyfiring as compared to air-blown atmospheric combustion and the role played by the different attrition/fragmentation paths were highlighted. In particular, it was noted that attrition could effectively enhance particle sulfation under oxyfiring conditions by continuously disclosing unconverted calcium to the sulfur-bearing atmosphere.

  17. Sludge combustion in fluidized bed reactors at laboratory scale; Esperienze di combustione di fanghi in reattori a letto fluido in scala di laboratorio

    Energy Technology Data Exchange (ETDEWEB)

    Chirone, R.; Cammarota, A. [Consiglio Nazionale delle Ricerche, Istituto di Ricerche sulla Combustione, Naples (Italy)

    2001-03-01

    The combustion of a dried sewage sludge in laboratory scale fluidized bed has been studied in Naples by the Istituto di ricerche sulla combustione (Irc) in the framework of a National project named Thermal Process with Energy Recovery to be used in laboratory and pre-pilot scale apparatus. The attention has been focused on emissions of unreacted carbon as elutriated fines, on the emissions of pollutant gases and on the assessment of the inventory of fly- and bottom ashes. The combustion behaviour of sewage sludge has been compared with those of a market available Tyre Derived Fuel (TDF) and a biomass from Mediterranean area (Robinia Pseudoacacia) and with that of a South African bituminous coal. Stationary combustion tests were carried out at 850{sup 0} C by feeding particles in the size range 0-1 mm into a bed of silica sand without any sorbent addition. The fluidized bed combustor has been operated, at a superficial gas velocity of 0.4 m/s and different excesses of air ranging between 14 and 98%. Relatively high combustion efficiency, larger than 98.9% has been obtained in experiments carried out with sewage sludge and excess of air larger than 20%. These values, are comparable with those obtained in previously experimental activity carried out under similar operative conditions with a South Africa Bituminous coal (97-98%). It is larger than those obtained by using a Tyre Derived Fuel (89-90%) and the Robinia Pseudoacacia Biomass (93-93%). The relative importance of carbon fines elutriation, CO emissions and volatile bypassing the bed in determining the loss of combustion efficiency has been evaluated for the different fuels tested. [Italian] Il lavoro riporta l'attivita' di ricerca condotta presso l'Istituto di ricerche sulla combustione (Irc-Cnr) nell'ambito del Progetto Processi termici con recupero di energia per lo smaltimento di fanghi e rifiuti speciali, sottoprogetto Combustione in letti fluidi in scala di laboratorio e pre-pilota di

  18. Evaluating possible industrial applications of combustible shales and shale ash wastes

    Directory of Open Access Journals (Sweden)

    Н. К. Кондрашева

    2016-08-01

    Full Text Available Today energy consumption is constantly growing while explored reserves of easily accessible oil are depleting, which is a reason why most countries tend to diversify their energy mix, develop non-hydrocarbon energy sources and use domestic types of fuel, including the low grade ones. Thereby interest is raised to such a source of hydrocarbons as combustible shales. Combustible shales appear to be one of the highest-potential types of organic raw materials, which may offset and in future even substitute oil products and gas. The paper is investigating behavior and structure of combustible shales during heat treatment in order to identify their possible industrial applications. A synchronous thermal analysis has been held, chemical composition of combustible shales’ mineral fraction and optimal conditions for shale fines briquetting have been determined.

  19. Characterisation of ashes produced by co-combustion of recovered fuels and peat

    Energy Technology Data Exchange (ETDEWEB)

    Frankenhaeuser, M.; Zevenhoven, R. [Borealis Polymers Oy, Porvoo (Finland); Skrifvars, B.J. [Aabo Akademi, Turku (Finland); Orjala, M. [VTT Energy, Espoo (Finland); Peltola, K. [Foster Wheeler Energy (Finland)

    1996-12-01

    Source separation of combustible materials from household or municipal solid waste yields a raw material for the production of Packaging Derived Fuel (PDF). This fuel can substitute the traditional fuels in heat and power generation and is also called recycled fuel. Co-combustion of these types of fuels with coal has been studied in several LIEKKI-projects and the results have been both technically and environmentally favourable. (author)

  20. Utilization of coal ash/coal combustion products for mine reclamation

    International Nuclear Information System (INIS)

    Dolence, R.C.; Giovannitti, E.

    1997-01-01

    Society's demand for an inexpensive fuel, combined with ignorance of the long term impacts, has left numerous scars on the Pennsylvania landscape. There are over 250,000 acres of abandoned surface mines with dangerous highwalls and water filled pits. About 2,400 miles of streams do not meet water quality standards because of drainage from abandoned mines. There are uncounted households without an adequate water supply due to past mining practices. Mine fires and mine subsidence plague many Pennsylvania communities. The estimated cost to reclaim these past scars is over $15 billion. The beneficial use of coal ash in Pennsylvania for mine reclamation and mine drainage pollution abatement projects increased during the past ten years. The increase is primarily due to procedural and regulatory changes by the Department of Environmental Protection (DEP). Prior to 1986, DEP required a mining permit and a separate waste disposal permit for the use of coal ash in backfilling and reclaiming a surface mine site. In order to eliminate the dual permitting requirements and promote mine reclamation, procedural changes now allow a single permit which authorize both mining and the use of coal ash in reclaiming active and abandoned pits. The actual ash placement, however, must be conducted in accordance with the technical specifications in the solid waste regulations

  1. Analysis of unburned carbon in industrial ashes from biomass combustion by thermogravimetric method using Boudouard reaction

    Czech Academy of Sciences Publication Activity Database

    Straka, Pavel; Náhunková, Jana; Žaloudková, Margit

    2014-01-01

    Roč. 575, JAN (2014), s. 188-194 ISSN 0040-6031 R&D Projects: GA MZe QI102A207 Institutional support: RVO:67985891 Keywords : unburned carbon * biomass * ash * thermogravimetry Subject RIV: GD - Fertilization, Irrigation, Soil Processing Impact factor: 2.184, year: 2014 http://www.sciencedirect.com/science/article/pii/S0040603113005455

  2. Atmospheric fluidized-bed combustion (AFBC) co-firing of coal and hospital waste

    International Nuclear Information System (INIS)

    1993-02-01

    The proposed project involves co-firing of coal and medical waste (including infectious medical waste) in an atmospheric fluidized-bed combustor (AFBC) to safely dispose of medical waste and produce steam for hospital needs. Combustion at the design temperature and residence time (duration) in the AFBC has been proven to render infectious medical waste free of disease producing organisms. The project would be located at the Veterans Affairs (VA) Medical Center in Lebanon, Pennsylvania. The estimated cost of the proposed AFBC facility is nearly $4 million. It would be jointly funded by DOE, Veterans Affairs, and Donlee Technologies, Inc., of York, Pennsylvania, under a cooperative agreement between DOE and Donlee. Under the terms of this agreement, $3.708 million in cost-shared financial assistance would be jointly provided by DOE and the Veterans Affairs (50/50), with $278,000 provided by Donlee. The purposes of the proposed project are to: (1) provide the VA Medical Center and the Good Samaritan Hospital (GSH), also of Lebanon, Pennsylvania, with a solution for disposal of their medical waste; and (2) demonstrate that a new coal-burning technology can safely incinerate infectious medical waste, produce steam to meet hospital needs, and comply with environmental regulations

  3. Three phase Eulerian-granular model applied on numerical simulation of non-conventional liquid fuels combustion in a bubbling fluidized bed

    Directory of Open Access Journals (Sweden)

    Nemoda Stevan Đ.

    2016-01-01

    Full Text Available The paper presents a two-dimensional CFD model of liquid fuel combustion in bubbling fluidized bed. The numerical procedure is based on the two-fluid Euler-Euler approach, where the velocity field of the gas and particles are modeled in analogy to the kinetic gas theory. The model is taking into account also the third - liquid phase, as well as its interaction with the solid and gas phase. The proposed numerical model comprise energy equations for all three phases, as well as the transport equations of chemical components with source terms originated from the component conversion. In the frame of the proposed model, user sub-models were developed for heterogenic fluidized bed combustion of liquid fuels, with or without water. The results of the calculation were compared with experiments on a pilot-facility (power up to 100 kW, combusting, among other fuels, oil. The temperature profiles along the combustion chamber were compared for the two basic cases: combustion with or without water. On the basis of numerical experiments, influence of the fluid-dynamic characteristics of the fluidized bed on the combustion efficiency was analyzed, as well as the influence of the fuel characteristics (reactivity, water content on the intensive combustion zone. [Projekat Ministarstva nauke Republike Srbije, br. TR33042: Improvement of the industrial fluidized bed facility, in scope of technology for energy efficient and environmentally feasible combustion of various waste materials in fluidized bed

  4. Biomass ash-bed material interactions leading to agglomeration in FBC

    DEFF Research Database (Denmark)

    Visser, H.J.M.; van Lith, Simone Cornelia; Kiel, J.H.A.

    2008-01-01

    -scale installations is "coating-induced" agglomeration. During reactor operation, a coating is formed on the surface of bed material grains and at certain critical conditions (e.g., coating thickness or temperature) sintering of the coatings initiates the agglomeration. In an experimental approach, this work...

  5. Radioactivity of wood ash; Puun tuhkan radioaktiivisuus

    Energy Technology Data Exchange (ETDEWEB)

    Rantavaara, A.; Moring, M

    2000-01-01

    STUK (Finnish Radiation and Nuclear Safety Authority) has investigated natural and artificial radioactivity in wood ash and radiation exposure from radionuclides in ash since 1996. The aim was to consider both handling of ash and different ways of using ash. In all 87 ash samples were collected from 22 plants using entirely or partially wood for their energy production in 1996-1997. The sites studied represented mostly chemical forest industry, sawmills or district heat production. Most plants used fluidised bed combustion technique. Samples of both fly ash and bottom ash were studied. The activity concentrations of radionuclides in samples of, e.g., dried fly ash from fuel containing more than 80% wood were determined. The means ranged from 2000 to less than 50 Bq kg{sup -1}, in decreasing order: {sup 137}Cs, {sup 40}K, {sup 90}Sr, {sup 210}Pb,{sup 226}Ra, {sup 232}Th, {sup 134}Cs, {sup 235}U. In bott radionuclide contents decreased in the same order as in fly ash, but were smaller, and {sup 210}Pb was hardly detectable. The NH{sub 4}Ac extractable fractions of activities for isotopes of alkaline elements (K, Cs) in bottom ash were lower than in fly ash, whereas solubility of heavier isotopes was low. Safety requirements defined by STUK in ST-guide 12.2 for handling of peat ash were fulfilled at each of the sites. Use of ash for land-filling and construction of streets was minimal during the sampling period. Increasing this type of ash use had often needed further investigations, as description of the use of additional materials that attenuate radiation. Fertilisation of forests with wood ash adds slightly to the external irradiation in forests, but will mostly decrease doses received through use of timber, berries, mushrooms and game meat. (orig.)

  6. Experimental study on fuel oil combustion in circulating fluidized bed; Estudio experimental sobre la combustion de combustoleo en lecho fluidizado circulante

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Rangel, Ricardo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    The Instituto de Investigaciones Electricas (IIE) developed a circulating fluidized bed combustor of 0.5 thermal MW unique in its type in Latin America. The Bachelor`s thesis entitled ``Experimental Study on Fuel Oil Combustion in Circulating Fluidized Bed`` was performed operating this combustor with the purpose of determining the feasibility of burning heavy fuel oil in a stable and sustained form, as well as the effect of the addition of calcium carbonate to the combustor. The results of the experimental trials showed heavy fuel oil can be burned in a circulating fluidized bed, with low sulfur dioxide emissions. During the conduction of the experiments a sulfur retention of 43% was achieved with a Ca/S relationship of 4.5. [Espanol] El Instituto de Investigaciones Electricas (IIE) desarrollo un combustor de lecho fluidizado circulante de 0.5 MW termicos de potencia, unico en su tipo en Latinoamerica. La tesis de licenciatura titulada Estudio Experimental sobre la Combustion de Combustoleo en Lecho Fluidizado Circulante se realizo operando dicho combustor, con el proposito de determinar la factibilidad de quemar combustoleo pesado en forma estable y autosostenida, asi como la influencia que tiene la adicion de carbonato de calcio al lecho. Los resultados de los ensayos experimentales mostraron que se puede quemar combustoleo pesado en un lecho fluidizado circulante, con bajas emisiones de bioxido de azufre. Durante la experimentacion se logro una retencion de azufre del 43%, con una relacion Ca/S de 4.5.

  7. Experimental study on fuel oil combustion in circulating fluidized bed; Estudio experimental sobre la combustion de combustoleo en lecho fluidizado circulante

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Rangel, Ricardo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1997-12-31

    The Instituto de Investigaciones Electricas (IIE) developed a circulating fluidized bed combustor of 0.5 thermal MW unique in its type in Latin America. The Bachelor`s thesis entitled ``Experimental Study on Fuel Oil Combustion in Circulating Fluidized Bed`` was performed operating this combustor with the purpose of determining the feasibility of burning heavy fuel oil in a stable and sustained form, as well as the effect of the addition of calcium carbonate to the combustor. The results of the experimental trials showed heavy fuel oil can be burned in a circulating fluidized bed, with low sulfur dioxide emissions. During the conduction of the experiments a sulfur retention of 43% was achieved with a Ca/S relationship of 4.5. [Espanol] El Instituto de Investigaciones Electricas (IIE) desarrollo un combustor de lecho fluidizado circulante de 0.5 MW termicos de potencia, unico en su tipo en Latinoamerica. La tesis de licenciatura titulada Estudio Experimental sobre la Combustion de Combustoleo en Lecho Fluidizado Circulante se realizo operando dicho combustor, con el proposito de determinar la factibilidad de quemar combustoleo pesado en forma estable y autosostenida, asi como la influencia que tiene la adicion de carbonato de calcio al lecho. Los resultados de los ensayos experimentales mostraron que se puede quemar combustoleo pesado en un lecho fluidizado circulante, con bajas emisiones de bioxido de azufre. Durante la experimentacion se logro una retencion de azufre del 43%, con una relacion Ca/S de 4.5.

  8. Organic emissions from co-combustion of RDF with wood chips and milled peat in a bubbling fluidized bed boiler

    International Nuclear Information System (INIS)

    Vesterinen, Raili; Flyktman, Martti

    1996-01-01

    Refuse derived fuel (RDF) has been burned with wood chips and milled peat in a 4 MW bubbling fluidized bed boiler. Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in flue gases expressed as TCDD-equivalents were significantly below the emission limit 0.1 ng/m 3 n I-TEQ (11 % O 2 ). Also the PCDD/F-concentrations of fly ashes separated by an electrostatic precipitator are significantly below the 1 ng/g I-TEQ limit for agricultural soil in Germany. The carbon monoxide content was rather high, but typical for many small district heating plants. The concentrations of other chlorinated aromatic compounds were also low, in some tests below the detection limit. The concentrations of polyaromatic hydrocarbons (PAH) were rather high. The leachable metal content of the fly ash generated were analyzed using U.S. EPA TCLP test (Toxicity Characteristic Leaching Procedure). All concentrations fell below boundary levels. (author)

  9. Analytical methods relating to mineral matter in coal and ash from coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Creelman, R.A. [Ultra-Systems Technology Pty. Ltd., Indooroopilly, Qld. (Australia)

    2002-07-01

    The paper begins by describing the minerals that occur in coal, as well as trace elements. The testing methods that are then described include those that are in the main the standard tools for the examination and assessment of minerals in coal and ash. The techniques discussed include optical and beam techniques, X-ray methods and a variety of other useful methods. 12 refs.

  10. Differentiation of volcanic ash-fall and water-borne detrital layers in the Eocene Senakin coal bed, Tanjung Formation, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L F; Moore, T A [US Geological Survey, Reston, VA (USA). National Center

    1993-02-01

    The Sangsang deposit of the Eocene Senakin coal bed, Tanjung Formation, southeastern Kalimantan, Indonesia, contains 11 layers, which are thin ([lt] 5 cm) and high in ash ([gt] 70%). These layers are characterized by their pelitic macroscopic texture. Examination of eight of the layers by scanning-electron microscopy, energy-dispersive X-ray, and X-ray diffraction analyses show that they are composed primarily of fairly well-crystallized kaolinite, much of which is vermicular. Accessory minerals include abundant Ti oxide, rare-earth element-rich Ca and Al phosphates, quartz that luminesces in the blue colour range, and euhedral to subhedral pyrooxene, hornblende, zircon, and sanidine. Although this mineral suite is suggestive of volcanic ash-fall material, only the four pelitic layers in the middle of the bed are thought to be solely derived from volcanic ash-falls on the basis of diagnostic minerals, replaced glass shards, and lithostratigraphic relationships observed in core and outcrop. The three uppermost pelitic layers contain octahedral chromites, some quartz grains that luminesce in the organic colour range, and some quartz grains that contain two-phase fluid inclusions. These layers are interpreted to be derived from a combination of volcanic ash-fall material and hydrologic transport of volcaniclastic sediment. In contrast, the lowermost pelitic layer, which contains large, rounded FeMg-rich chromites, is thought to have been dominantly deposited by water. The source of the volcanic ash-fall material may have been middle Tertiary volcanism related to plate tectonic activity between Kalimantan and Sulawesi. The volcanic ash was deposited in sufficient amounts to be preserved as layers within the coal only in the northern portions of the Senakin region: the southern coal beds in the region do not contain pelitic layers. 29 refs., 8 figs., 3 tabs.

  11. Silica from Ash

    Indian Academy of Sciences (India)

    management, polymer composites and chemical process design. Figure 1 Difference in color of the ash ... The selection of ash is important as the quality of ash determines the total amount as well as quality of silica recoverable Ash which has undergone maximum extent of combustion is highly desirable as it contains ...

  12. Feasibility study of a granular bed prefilter for purifying combustion gases from a solid radioactive waste incinerator

    International Nuclear Information System (INIS)

    Girod, M.

    1993-01-01

    The purpose of incineration is to minimize the volumes of radioactive waste to be stored. Cleaning combustion gases from these incinerators requires prefilters to protect the very high efficiency filters (known by the French acronym THE). These prefilters should make it possible to recover products such as plutonium while at the same time presenting a very limited source of secondary waste. This document sets out the feasibility study for a granular bed prefilter. This bed should be made of a material which is itself combustible so that it can be recycled in the incinerator to minimize production of secondary waste. During an initial stage, a design study of a demonstration device was carried out using a calculation code constructed on the basis of existing physical models, and which makes it possible to forecast the performance of the support. This theoretical approach has been correlated against experimental results from the validation test. During a second stage, the study dealt with the selection of the material from which the bed was made as well as quantification of the release of radiation during incineration of the plutonium contamined material. In this way, the very low transfer of radioactivity into the gaseous phase was demonstrated. Finally, during a third stage, a study of the change in efficiency and the loss of charge of a granular bed filter was carried out during industrial operation using an incinerator. In conclusion, it was demonstrated that the granular bed represents a viable solution for prefiltering at 200 deg C. Research might develop along a different path and involve using the granular bed as a high temperature filter at 500 to 600 deg C

  13. Modelling of NOx emissions from pressurized fluidized bed combustion - A parameter study

    DEFF Research Database (Denmark)

    Jensen, Anker; Johnsson, Jan Erik

    1997-01-01

    velocity, the bubble size, the bubble rise velocity and the gas interchange coefficient between bubble and dense phase. The most important combustion parameters are the rates of CO and CH4 combustion and the CO/(CO + CO2) ratio from char combustion. (C) 1997 Elsevier Science Ltd....

  14. Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

    KAUST Repository

    Andersen, Myrrha E.; Modak, Nabanita; Winterrowd, Christopher K.; Lee, Chun Wai; Roberts, William L.; Wendt, Jost O L; Linak, William P.

    2016-01-01

    -fired combustion conditions consists primarily of carbonaceous material (50-95%). Carbonaceous components on particles <0.6. μm measured by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation

  15. Enrichment of trace elements in bottom ash from coal oxy-combustion: Effect of coal types

    CSIR Research Space (South Africa)

    Oboirien, BO

    2016-09-01

    Full Text Available In this study, the enrichment of trace elements in two coals under air and oxy-combustion conditions was studied. Twenty-one trace elements were evaluated. The two coal samples had a different concentration for the 21 trace elements, which was due...

  16. Application of wasted sea-shell to desulfurizer in fluidized bed coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Naruse, Ichiro; Saito, Katsuhiro; Murakami, Takahiro

    1999-07-01

    Almost all wasted seashells consist of CaCo{sub 3}, and are similar to limestone. It would be proposed that the seashell could be applied as a desulfurizer. In this study, desulfurization characteristics of the seashell are fundamentally studied by using a thermobalance and a bubbling fluidized coal combustor with comparing the results obtained by limestone as a reference. Under the constant calcination temperature, the desulfurization efficiency for the seashells attains more than about 70% after the desulfurization period of 30 h. For the limestones, on the other hand, the desulfurization efficiency becomes only 38%. Under practical conditions of fluidized bed coal combustion, the desulfurization efficiency for the seashells also indicates higher value than that for the limestones. The desulfurization efficiency depends on the pore size distribution of CaO rather than its specific surface area. The mean pore size of the calcined seashell is about 10 times as large as that of the calcined limestones. from Scanning Electro-Microscope (SEM) photos of the surface of CaCO{sub 3}, CaO and the sulfurized particles of the seashells the large pores can be observed. In measuring cross-sectional distribution of sulfur inside the particles by using an Energy Dispersed X-ray (EDX) system, the sulfur in the sulfurized particle of limestone is only trapped near the particle surface. For the seashells, whereas, the sulfur is distributed over the whole body of particle. Desulfurization efficiency for the limestone, into which some alkali metal compounds are added, increases with increasing the concentration of alkali metal compounds added. In order of increasing effect the key elemental species to enhance the desulfurization activities are Cl, Na and K. Alkali metal compounds can enhance the desulfurization activities, due to solution of CaO in molten NaCl. This is one of the reasons why the desulfurization efficiency for the seashells improves.

  17. Chemical composition of leachate of dairy manure mixed with fluidized bed combustion residue

    Energy Technology Data Exchange (ETDEWEB)

    Elrashidi, M.A.; Baligar, V.C.; Korcak, R.F.; Persaud, N.; Ritchey, K.D. [USDA-ARS-ASWCRL, Beaver, WV (United States)

    1999-07-01

    This study was initiated to investigate the hypothesis that using Fluidized Bed Combustion (FBC) residue to stabilize a dairy feedlot surface (DFS) could enhance element attenuation and minimize the environmental impact on water quality. The laboratory leaching experiment included FBC, dairy manure (DM), and DM/FBC treatments. The leaching process consisted of 10 weekly additions of distilled water, each of 460 mL. Using FBC with DM decreased the concentration of most elements (e.g., P. N, K, Ca, Al, Si, Fe, Mn, Cu, Zn, Pb, Cd, Co, Cr, Ni, As and Se) in the leachate. A decrease ranging from 5.6 to 100% was obtained. The presence of high concentration of dissolved organic matter (DOM) is believed to enhance element attenuation by FBC minerals (e.g., Fe-, and Al-oxides). Several mechanisms involved in this process are proposed: (1) formation of insoluble metal-organic complexes; (2) sorption of soluble organic and inorganic species on mineral surfaces; and (3) precipitation of soluble inorganic species. These mechanisms are discussed in relation to each of the measured elements. On the other hand, using FBC with DM appeared to increase the concentration of B (235%), S (47.3%), and Mg (36.5%) in the leachate. Reactions of DM with FBC minerals to form soluble organic complexes were suggested to explain B and S increases. The increase in leached Mg could be attributed to the presence of SO{sub 4}{sup 2-}. The results provide evidence that using FBC to stabilize DFS has the advantage of immobilizing a large portion of most elements present in DM leachate. 41 refs., 3 figs., 2 tabs.

  18. Chemical composition of leachate of dairy manure mixed with fluidized bed combustion residue

    Energy Technology Data Exchange (ETDEWEB)

    Elrashidi, M.A.; Baligar, V.C.; Korcak, R.F.; Persaud, N.; Ritchey, K.D.

    1999-08-01

    This study was initiated to investigate the hypothesis that using fluidized bed combustion (FBC) residue to stabilize a dairy feedlot surface (DFS) could enhance element attenuation and minimize the environmental impact on water quality. The laboratory leaching experiment included FBC, dairy manure (DM), and DM/FBC treatments. The leaching process consisted of 10 weekly additions of distilled water, each of 460 mL. Using FBC with DM decreased the concentration of most elements (e.g., P, N, K, Ca, Al, Si, Fe, Mn, Cu, Zn, Pb, Cd, Co, Cr, Ni, As, and Se) in the leachate. A decrease ranging from 5.6 to 100% was obtained. The presence of high concentration of dissolved organic matter (DOM) is believed to enhance element attenuation by FBC minerals. Several mechanisms involved in this process are proposed: (1) formation of insoluble metal-organic complexes; (2) sorption of soluble organic and inorganic species on mineral surfaces; and (3) precipitation of soluble inorganic species. These mechanisms are discussed in relation to each of the measured elements. On the other hand, using FBC with DM appeared to increase the concentration of B, S, and Mg in the leachate. Reactions of DOM with FBC minerals to form soluble organic complexes were suggested to explain B and S increases. The increase in leached Mg could be attributed to the presence of SO{sub 4}{sup 2{minus}}. Their results provide evidence that using FBC to stabilize DFS has the advantage of immobilizing a large portion of most elements present in DM leachate.

  19. Quality of diets with fluidized bed combustion residue treatment: I. Rat trials

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, N.J.; Reid, R.L.; Head, M.K.; Hern, J.L.; Bennett, O.L.

    Feeding trials were conducted with rats (Rattus rattus) to examine effects of soil application, or dietary inclusion, of fluidized bed combustion residue (FBCR) on the composition and quality of foods. Four diets (vegetable protein, egg protein, chicken, chicken + dietary FBCR) prepared with either FBCR or lime (control) treatments, were fed to weanling, female rats in three growth and reproduction trials. Intake, growth rate, and composition of body and organs of rats were measured. Rats in one trial were bred, their litters maintained on dietary treatments, and the offspring rebred. Treatment (FBCR vs. lime) x diet interactions on food composition and animal responses generally were not significant. Treatment had little effect on element composition of diets; mineral concentrations were in normal ranges. Diet treatment with FBCR depressed (P<0.01) food intake and growth of rats in one trial, but not in others, and had no effect (P<0.05) on body water, protein, ether extract, or gross energy composition. Some differences in element concentrations in the carcass and organs of rats and pups resulted from FBCR treatment, but effects were small and inconsistent. Litters from the first reproductive cycle appeared normal, except for animals fed the chicken + dietary FBCR treatment, on which pups showed poor growth and anemia. Offspring from certain diets were rebred and litters showed a high mortality, although this was not associated specifically with FBCR treatment. Results indicated no major detrimental effects on food composition, or growth, tissue element accumulation, and reproduction in the rat relating to use of FBCR as a soil amendment. 20 refs., 9 tabs.

  20. Quality of diets with fludized bed combustion residue treatment: II. Swine trials

    Energy Technology Data Exchange (ETDEWEB)

    Whitsel, T.J.; Reid, R.L.; Stout, W.L.; Hern, J.L.; Bennett, O.L.

    Growing pigs (Sus scrofa domesticus) were fed for an 8-wk period in two trials on diets produced on soils treated with fluidized bed combustion residue (FBCR) or limestone. Diets contained corn (Zea mays L.) and wheat (Triticum aestivum L.) mixtures with soybean (Glycine max (L.) Merr.) meal, supplemented with vegetables, fruits, and meat. Pigs were fed ad libitum and effects of diet treatment on rate of gain, N balance, blood composition, and element composition of the carcass and organs were determined. The FBCR diet caused a decrease (P<0.05 in Trial 1, P <0.07 in Trial 2) in body weight gains of pigs, but increased (P<0.05) N retention in one trial. Blood composition was not influenced markedly by diet treatment, with small but significant differences in serum Ca, triglycerides, certain amino acids, and whole blood Pb concentrations; effects were not consistent between trials. Urinary As concentration was slightly higher for pigs on FBCR diets. Analysis of the carcass and organs of pigs slaughtered posttrial showed significant differences in element levels from those of pretrial animals, but differences in tissue mineral concentrations related to diet treatment were few and inconsistent. Element concentrations in the organs of pigs were within normal ranges. No explanation for the depression in weight gain of pigs fed FBCR-treated diets was found. Except for the weight response, results support data from other trials with laboratory animals showing no apparent adverse effects of FBCR application to soils on nutritive quality of foods. 24 refs., 1 fig., 10 tabs.

  1. Development and application of a high-temperature sampling probe for burning chamber conditions of fluidized-bed combustion; Korkean laempoetilan naeytteenottosondin kehittaeminen ja soveltaminen leijukerrospolton tulipesaeolosuhteisiin

    Energy Technology Data Exchange (ETDEWEB)

    Larjava, K.; Paerkkae, M.; Jormanainen, P.; Roine, J.; Paakkinen, K. [VTT Chemistry, Espoo (Finland); Linna, V. [VTT Energy, Jyvaeskylae (Finland)

    1996-12-01

    A sampling probe for the burning chamber conditions of fluidized-bed combustion will be developed in this project. The probe will be suitable for sampling vaporous heavy and alkali metals and other condensing compounds (e.g. chlorides) as well combustion gases and alternatively also flue gas particles at high temperatures. The knowledge gained with the probe will help understanding, developing and modeling combustion processes and will thus aid the manufacturers of the boilers. (author)

  2. Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

    International Nuclear Information System (INIS)

    Sun, Rui; Ismail, Tamer M.; Ren, Xiaohan; Abd El-Salam, M.

    2015-01-01

    Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW

  3. Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Rui, E-mail: Sunsr@hit.edu.cn [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Ismail, Tamer M., E-mail: temoil@aucegypt.edu [Department of Mechanical Engineering, Suez Canal University, Ismailia (Egypt); Ren, Xiaohan [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Abd El-Salam, M. [Department of Basic Science, Cairo University, Giza (Egypt)

    2015-05-15

    Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW.

  4. Differentiation of volcanic ash-fall and water-borne detrital layers in the Eocene Senakin coal bed, Tanjung Formation, Indonesia

    Science.gov (United States)

    Ruppert, L.F.; Moore, T.A.

    1993-01-01

    The Sangsang deposit of the Eocene Senakin coal bed, Tanjung Formation, southeastern Kalimantan, Indonesia, contains 11 layers, which are thin ( 70%). These layers are characterized by their pelitic macroscopic texture. Examination of eight of the layers by scanning-electron microscopy, energy-dispersive X-ray, and X-ray diffraction analyses show that they are composed primarily of fairly well-crystallized kaolinite, much of which is vermicular. Accessory minerals include abundant Ti oxide, rare-earth element-rich Ca and A1 phosphates, quartz that luminescences in the blue color range, and euhedral to subhedral pyroxene, hornblende, zircon, and sanidine. Although this mineral suite is suggestive of volcanic ash-fall material, only the four pelitic layers in the middle of the bed are thought to be solely derived from volcanic ash-falls on the basis of diagnostic minerals, replaced glass shards, and lithostratigraphic relationships observed in core and outcrop. The three uppermost pelitic layers contain octahedral chromites, some quartz grains that luminesce in teh orange color range, and some quartz grains that contain two-phase fluid inclusions. These layers are interpreted to be derived from a combination of volcanic ash-fall material and hydrologic transport of volcaniclastic sediment. In contrast, the lowermost pelitic layer, which contains large, rounded FeMg-rich chromites, is thought to have been dominantly deposited by water. The source of the volcanic ash-fall material may have been middle Tertiary volcanism related to plate tectonic activity between Kalimantan and Sulawesi. The volcanic ash was deposited in sufficient amounts to be preserved as layers within the coal only in the northern portions of the Senakin region: the southern coal beds in the region do not contain pelitic layers. ?? 1993.

  5. Fluidized bed ash and passive treatment reduce the adverse effects of acid mine drainage on aquatic organisms.

    Science.gov (United States)

    Porter, Clint M; Nairn, Robert W

    2010-10-15

    Elevated concentrations of acidity and metals in acid mine drainage (AMD) may be effectively addressed by active and passive treatment technologies. However, typical evaluations consider only chemical water quality with little if any regard for biological metrics. Robust evaluations including both chemical and biological indicators of water quality improvement are needed. In this study, injection of alkaline fluidized bed ash (FBA) into a flooded underground coal mine was coupled with a five-cell passive treatment system to ameliorate an abandoned AMD discharge in eastern Oklahoma. The passive system included process units promoting both aerobic and anaerobic treatment mechanisms. Resulting water quality changes and biological responses were evaluated. Organisms of two distinct functional groups (the filter-feeding mollusk Corbicula fluminea and the wide-spectrum feeding fish Lepomis macrochirus) were exposed to mine waters in several treatment cells. The combination of treatment technologies was hypothesized to limit potential negative effects on these aquatic organisms. Tissues were harvested and analyzed for concentrations of several metals (Al, Fe, Mn, Mg, Ca, Ni, Cu and Zn) of interest. Organismal responses, such as hepatosomatic index, condition factor, and condition index, did not vary significantly among organisms exposed within different treatment cells when compared to non-AMD impaired waters. Metal tissue accumulation trends, compared to aqueous concentrations, were observed for Fe, Ni and Zn. Exposure experiments with these two organisms indicated that FBA introductions coupled with passive treatment decreased the potential adverse effects of AMD to biological systems. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Combustion

    CERN Document Server

    Glassman, Irvin

    1987-01-01

    Combustion, Second Edition focuses on the underlying principles of combustion and covers topics ranging from chemical thermodynamics and flame temperatures to chemical kinetics, detonation, ignition, and oxidation characteristics of fuels. Diffusion flames, flame phenomena in premixed combustible gases, and combustion of nonvolatile fuels are also discussed. This book consists of nine chapters and begins by introducing the reader to heats of reaction and formation, free energy and the equilibrium constants, and flame temperature calculations. The next chapter explores the rates of reactio

  7. Effects of gas conditions on ASH induced agglomeration

    DEFF Research Database (Denmark)

    Ma, T.; Fan, C. G.; Hao, L. F.

    2016-01-01

    Agglomeration is a serious problem for gasification and combustion of biomass in fluidized bed. Agglomeration characteristics may be affected by gas condition, but the literature is quite vague in this regard. This study focuses on the effects of gasification and combustion condition...... on agglomeration tendency with two types of biomass ash, including rice straw and wheat straw ash. The agglomerates are analyzed by SEM-EDS for morphology and elemental composition. Defluidization temperature (Td) in those two types of gas conditions is quite different. Tdin gasification condition is much lower...

  8. Experimental investigation of wood combustion in a fixed bed with hot air

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, Miladin, E-mail: m.markovic@utwente.nl; Bramer, Eddy A.; Brem, Gerrit

    2014-01-15

    Highlights: • Upward combustion is a new combustion concept with ignition by hot primary air. • Upward combustion has three stages: short drying, rapid devolatilization and char combustion. • Variation of fuel moisture and inert content have little influence on the combustion. • Experimental comparison between conventional and upward combustion is presented. - Abstract: Waste combustion on a grate with energy recovery is an important pillar of municipal solid waste (MSW) management in the Netherlands. In MSW incinerators fresh waste stacked on a grate enters the combustion chamber, heats up by radiation from the flame above the layer and ignition occurs. Typically, the reaction zone starts at the top of the waste layer and propagates downwards, producing heat for drying and devolatilization of the fresh waste below it until the ignition front reaches the grate. The control of this process is mainly based on empiricism. MSW is a highly inhomogeneous fuel with continuous fluctuating moisture content, heating value and chemical composition. The resulting process fluctuations may cause process control difficulties, fouling and corrosion issues, extra maintenance, and unplanned stops. In the new concept the fuel layer is ignited by means of preheated air (T > 220 °C) from below without any external ignition source. As a result a combustion front will be formed close to the grate and will propagate upwards. That is why this approach is denoted by upward combustion. Experimental research has been carried out in a batch reactor with height of 4.55 m, an inner diameter of 200 mm and a fuel layer height up to 1 m. Due to a high quality two-layer insulation adiabatic conditions can be assumed. The primary air can be preheated up to 350 °C, and the secondary air is distributed via nozzles above the waste layer. During the experiments, temperatures along the height of the reactor, gas composition and total weight decrease are continuously monitored. The influence of

  9. The emissions of VOCs during co-combustion of coal with different waste materials in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    I. Gulyurtlu; P. Abelha; A. Gregorio; A. Garcia-Garcia; D. Boavida; A. Crujeira; I. Cabrita [DEECA-INETI, Lisbon (Portugal)

    2004-06-01

    The combustion of different fuels gives rise to the formation of small but appreciable amounts of volatile organic compounds (VOCs). They basically result from incomplete combustion and their emissions have negative repercussions on health and on the environment in general. As their measurement is difficult, costly, and very time-consuming, very little is reported on the emissions of VOCs from combustion installations. In this study, various blends of two different coals with several wastes were burned in a pilot-scale fluidized bed combustor and measurements of VOCs at several locations along the combustor height as well as just before the stack were carried out. The results demonstrate that the parameters important for the formation of VOCs are temperature, excess air levels, and the effectiveness of the mixing of air with fuel. Furthermore, it was observed that coal was the principal source of VOCs, but the combustion of volatiles from fuels such as biomass, occurring in the freeboard, was important in reducing the emissions of VOCs to almost zero. 8 refs., 6 figs., 6 tabs.

  10. Experimental investigation of wood combustion in a fixed bed with hot air

    NARCIS (Netherlands)

    Markovic, Miladin; Bramer, Eduard A.; Brem, Gerrit

    2014-01-01

    Waste combustion on a grate with energy recovery is an important pillar of municipal solid waste (MSW) management in the Netherlands. In MSW incinerators fresh waste stacked on a grate enters the combustion chamber, heats up by radiation from the flame above the layer and ignition occurs. Typically,

  11. Brazilian experience on fluidized bed combustion; Experiencia brasileira em leito fluidizado

    Energy Technology Data Exchange (ETDEWEB)

    Chazan, David Turik [CIENTEC, Porto Alegre, RS (Brazil)

    1988-12-31

    The aim of this work is to outline the evolution of the development of fluidized combustion in the main institutions which uses fluidized combustion of coal and other fossil fuels, industrial and agricultural wastes and biomass at industrial level in Brazil. (author) 1 fig.

  12. Combustion

    CERN Document Server

    Glassman, Irvin

    2008-01-01

    Combustion Engineering, a topic generally taught at the upper undergraduate and graduate level in most mechanical engineering programs, and many chemical engineering programs, is the study of rapid energy and mass transfer usually through the common physical phenomena of flame oxidation. It covers the physics and chemistry of this process and the engineering applications-from the generation of power such as the internal combustion automobile engine to the gas turbine engine. Renewed concerns about energy efficiency and fuel costs, along with continued concerns over toxic and particulate emissions have kept the interest in this vital area of engineering high and brought about new developments in both fundamental knowledge of flame and combustion physics as well as new technologies for flame and fuel control. *New chapter on new combustion concepts and technologies, including discussion on nanotechnology as related to combustion, as well as microgravity combustion, microcombustion, and catalytic combustion-all ...

  13. Beneficial use of CFB ash in pavement construction applications

    Energy Technology Data Exchange (ETDEWEB)

    N. Mike Jackson; Scott Schultz; Paul Sander; Lindsay Schopp [Jackson Research Engineers, Inc., Ponte Vedra Beach, FL (United States)

    2009-07-15

    The disposal of ash produced from the combustion of solid fuels has been a major subject of research and product development for many years. An innovative application has recently been employed by JEA to recycle both the bottom ash and fly ash from two new circulating fluidized bed (CFB) boilers as a stabilizer for local sandy soils and pavement base course material. The results of laboratory testing and field applications in the north Florida market area illustrate how this by-product is adding value in pavement and roadway construction applications. 14 refs., 2 figs., 10 tabs.

  14. Volatiles combustion in fluidized beds. Technical progress report, 4 March 1993--3 June 1993

    Energy Technology Data Exchange (ETDEWEB)

    Hesketh, R.P.

    1993-09-01

    The goal of this project is to investigate the conditions in which volatiles will burn within both the dense and freeboard regions of fluidized beds. Experiments using a fluidized bed operated at incipient fluidization will be performed to characterize the effect of particle surface area, initial fuel concentration, and particle type on the inhibition of volatiles within a fluidized bed. The work conducted during the period 4 March, 1993 through 3 June, 1993 is reported in this technical progress report. The work during this time period consists primarily of the startup and trouble shooting of the fluidized bed reactor and gas phase modeling of methane and propane.

  15. Development of fluidized bed combustion of biomass; Leijupolttoprosessin kehittaeminen vaikeille biopolttoaineille soveltuvaksi

    Energy Technology Data Exchange (ETDEWEB)

    Hiltunen, M; Vaehaenen-Koivuluoma, T [Foster Wheeler Energia Oy, Karhula (Finland)

    1997-10-01

    Some commercial BFB boilers burning biofuels, or biofuels and industrial wood wastes have suffered serious problems in bed material sintering. In worst cases the cumulation of reactive alkali compounds has caused total sintering of bed material even during a few days` operation. This presentation reports the results obtained from three separate cases, where sintering problems occurred. Boiler A burned biofuel with quartz sand and limestone addition. Boiler B burned softwood bark and industrial wood waste with sand addition. Boiler C burned softwood bark and sludge with sand addition. Due to the fuel used, bed sintering occurred in all boilers. Obviously, sintering was also influenced by some technical problems. Bed material samples have been analyzed with XRF and SEM-EDS techniques. According to these analyses, the main reason for sintering in boiler A is the cumulation of reactive potassium in bed material. In boiler B, the main reason is the fuel change from a mixture of softwood bark and industrial wood waste to pure industrial wood waste. The extra load of reactive sodium exceeded the critical concentration of alkali compounds in bed material. Also in boiler C, the fuel change from a mixture of softwood bark and sludge to pure softwood bark seems to be one of the reasons for bed sintering. After the fuel change the bed saturated with reactive potassium and the bed sintered. (orig.)

  16. Regenerable cobalt oxide loaded magnetosphere catalyst from fly ash for mercury removal in coal combustion flue gas.

    Science.gov (United States)

    Yang, Jianping; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

    2014-12-16

    To remove Hg(0) in coal combustion flue gas and eliminate secondary mercury pollution of the spent catalyst, a new regenerable magnetic catalyst based on cobalt oxide loaded magnetospheres from fly ash (Co-MF) was developed. The catalyst, with an optimal loading of 5.8% cobalt species, attained approximately 95% Hg(0) removal efficiency at 150 °C under simulated flue gas atmosphere. O2 could enhance the Hg(0) removal activity of magnetospheres catalyst via the Mars-Maessen mechanism. SO2 displayed an inhibitive effect on Hg(0) removal capacity. NO with lower concentration could promote the Hg(0) removal efficiency. However, when increasing the NO concentration to 300 ppm, a slightly inhibitive effect of NO was observed. In the presence of 10 ppm of HCl, greater than 95.5% Hg(0) removal efficiency was attained, which was attributed to the formation of active chlorine species on the surface. H2O presented a seriously inhibitive effect on Hg(0) removal efficiency. Repeated oxidation-regeneration cycles demonstrated that the spent Co-MF catalyst could be regenerated effectively via thermally treated at 400 °C for 2 h.

  17. Reuse of partially sulphated CFBC ash as an SO{sub 2} sorbent

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.; Jia, L.; Anthony, E.J. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy; Nobili, M.; Telesca, A. [Basilicata Univ., Potenza (Italy). Dept. of Environmental Engineering and Physics; Montagnaro, F. [Naples Univ., Naples (Italy). Dept. of Chemistry

    2010-06-15

    Ash produced from circulating fluidized bed combustion (CFBC) boilers typically contains large amounts of unreacted calcium oxide (CaO) when limestone is added into the combustor for in situ removal of sulphur dioxide (SO{sub 2}). This paper reported on a study that evaluated the reactivation of partially sulphated ash obtained from an industrial circulating fluidized bed combustion (CFBC) boiler by hydration with liquid water and steam. A pilot-scale mini-CFBC was used to evaluate the results of reactivation on the bed ash by hydrating with liquid water and admixtures of sodium carbonate (Na{sub 2}CO{sub 3}) in solution or as powder. Re-sulphation tests on the hydrated samples were performed in a Cahn 1000 thermogravimetric analyzer (TGA) at 850 degrees C for 90 minutes in a simulated flue gas environment with sulphur dioxide (SO{sub 2}) concentration at 5000 ppm. Re-sulphation was carried out on unhydrated ash at the same conditions used in the baseline test. The TGA results showed that although liquid water and steam successfully hydrate and reactivate the unreacted CaO in the bed ash, the treated ashes sulphated to widely different extents. Attempts to reactivate fly ash with hydration failed, but the fly ash by itself was extremely reactive. When the treated ash was re-injected into the combustor with the fuel, the effect on SO{sub 2} removal efficiency was negligible if Na{sub 2}CO{sub 3} was added as powder. Doping with aqueous solution improved SO{sub 2} removal, but to a lesser extent than if only water hydration was used. Increasing the amount of water to reactivate the ash did not improve the sulphur capture capacity in the mini-CFBC. It was concluded that reactivation by water is the most practical way to reuse the partially sulphated bed ash as a sulphur sorbent. 21 refs., 7 tabs., 3 figs.

  18. Combustion of gases released from peat or biomass in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Raiko, R. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1996-12-01

    Temperature and gas concentration experiments have been conducted to determine at what temperature carbon monoxide, methane and propane begin to react within the particulate phase of a bubbling fluidized bed. The fluidized bed reactor used in these experiments was a stainless-steel tube with an internal diameter of 50 mm surrounded by an electric heater. Two different natural quartz sands were used (d{sub p} =0.35 mm and 0.6 mm). The bed height used varied between 100 and 260 mm (in unfluidized state). A porous plate distributor, made of kaowool, was used to avoid jets appearing at the distributor. The bed was operated at incipient fluidization (u = 5.9-9 cm/s). The bed temperatures used ranged from 600 deg C to 850 deg C. It was found that carbon monoxide, methane and propane react inside a fluidized bed, but often other conditions than temperature have a considerable effect on the rate of the reaction. The critical temperature was found to be 650 deg C for propane and carbon monoxide and 700 deg C for methane. With under-stoichiometric mixture of carbon monoxide and air the heat release can be over 2.5 MW/m{sup 3} when bed temperature is 650 deg C. According to these experiments it is obvious that the reaction mechanism for carbon monoxide oxidation inside a fluidized bed differs greatly from that of gas phase only. The results of our more than 1300 test runs show clearly the varying effects of the different bed materials. Even with the same bed material totally different results can be obtained. In order to elucidate the possible changes of particle surface, microscopic and porosimetric studies was conducted with both fresh bed particles and used bed particles. Also the effect of commonly used ingredients, like limestone and dolomite, was tested. A global model for carbon monoxide oxidation inside a fluidized bed was introduced. The model was tested against measured data from the laboratory-scale fluidized bed test rig. (Abstract Truncated)

  19. Fluidised bed combustion: a new route to power and heat from coal

    Energy Technology Data Exchange (ETDEWEB)

    Schilling, H D [Bergbau-Forschung G.m.b.H., Essen (Germany, F.R.)

    1978-02-01

    The functioning of fluidized-bed firings and their advantages with regard to SO/sub 2/ emissions are described. The principle of design of a fluidized-bed boiler and a gas/steam turbine power plant with fluidized-bed firing under pressure is outlined. The application and their economics in heat and power generation and marketing potential of fluidized-bed firings and their economics in heat and power generation is pointed out. The construction of waste-fired incinerators has already become possible, but there is still a lot of development work to be done until fluidized-bed firings can be used in central heatings, combined-cycle power plants, and large power plants.

  20. Combustion

    CERN Document Server

    Glassman, Irvin

    1997-01-01

    This Third Edition of Glassman's classic text clearly defines the role of chemistry, physics, and fluid mechanics as applied to the complex topic of combustion. Glassman's insightful introductory text emphasizes underlying physical and chemical principles, and encompasses engine technology, fire safety, materials synthesis, detonation phenomena, hydrocarbon fuel oxidation mechanisms, and environmental considerations. Combustion has been rewritten to integrate the text, figures, and appendixes, detailing available combustion codes, making it not only an excellent introductory text but also an important reference source for professionals in the field. Key Features * Explains complex combustion phenomena with physical insight rather than extensive mathematics * Clarifies postulates in the text using extensive computational results in figures * Lists modern combustion programs indicating usage and availability * Relates combustion concepts to practical applications.

  1. Leaching of PAHs from agricultural soils treated with oil shale combustion ash: an experimental study.

    Science.gov (United States)

    Jefimova, Jekaterina; Adamson, Jasper; Reinik, Janek; Irha, Natalya

    2016-10-01

    The present study focuses on the fate of polycyclic aromatic hydrocarbons (PAHs) in soils amended with oil shale ash (OSA). Leachability studies to assess the release of PAHs to the environment are essential before the application of OSA in agriculture. A quantitative estimation of the leaching of PAHs from two types of soil and two types of OSA was undertaken in this study. Two leaching approaches were chosen: (1) a traditional one step leaching scheme and (2) a leaching scheme with pretreatment, i.e.., incubation of the material in wet conditions imitating the field conditions, followed by a traditional leaching procedure keeping the total amount of water constant. The total amount of PAHs leached from soil/OSA mixtures was in the range of 15 to 48 μg/kg. The amount of total PAHs leached was higher for the incubation method, compared to the traditional leaching method, particularly for Podzolic Gleysols soil. This suggests that for the incubation method, the content of organic matter and clay minerals of the soil influence the fate of PAHs more strongly compared to the traditional leaching scheme. The amount of PAHs leached from OSA samples is higher than from soil/OSA mixtures, which suggests soils to inhibit the release of PAHs. Calculated amount of PAHs from experimental soil and OSA leaching experiments differed considerably from real values. Thus, it is not possible to estimate the amount of PAHs leached from soil/OSA mixtures based on the knowledge of the amount of PAHs leached from soil and OSA samples separately.

  2. Associative properties of 137Cs in biofuel ashes

    International Nuclear Information System (INIS)

    Ravila, A.; Holm, E.

    1999-01-01

    The present study aims to reveal how radiocesium is associated to the ash particles derived from biofuel combustion. A sequential extraction procedure was carried out for the characterisation of radiocesium speciation in ash generated by different fuels and burner types. The ash types considered were fly ash and bottom ash collected from Swedish district heating plants using bark wood or peat as fuel. A fraction of the radiocesium in biofuel ash can easily become solubilised and mobilised by water and also, a significant fraction of the radionuclides can be bound to the ash particles in cation-exchangeable forms. Therefore, at using the ash derived from biofuels to recycle mineral nutrients for forestry or short rotation coppicing, radiocesium solubilised and leached from the ash by rains has a potential to rather quickly enter the rooting zone of forest vegetation or energy crops. On the other hand, radiocesium strongly bound to the ash will migrate slowly into the soil column with the successive accumulation of litter and in the process act to maintain the external dose rate at an elevated level for a long time. The results of the sequential extraction procedure and activity determination of the different extracted fractions implies that the bioavailable fraction of radiocesium in ash from bark, wood or peat is in the range between 20-85% of the total ash contents. Peat ash collected from a powder burner strongly retained a large fraction (70-90%) of its radiocesium content while the peat ash from a continuos fluidized bed type burner retained nearly 100% of the radiocesium in the bottom ash and only about 15% in the fly ash

  3. Use of nitrogen stable isotope analysis to understand char nitrogen evolution during the fluidized-bed co-combustion of coal and sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Ana Arenillas; Roberto Garcia; Chenggong Sun; Colin E. Snape; Angel H. Moreno; Fernando Rubiera; Jose J. Pis [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

    2005-04-01

    NOx emissions from sewage sludge combustion are a concern, because of the usually high nitrogen content of this fuel. The interactions during co-combustion in a fluidized-bed reactor of sewage sludge and a bituminous coal were evaluated, in relation to the nitrogen evolution during the combustion process. The nitrogen stable isotope measurements provide novel results regarding the tracing of nitrogen during combustion. Our preliminary results show that the co-combustion chars retain more nitrogen than expected, with the additional nitrogen being mainly derived from the sludge. Additional measurements are planned on the resultant co-combustion gases, to aid source apportionment of the NOx arising from coal/sewage interactions. 14 refs., 3 figs., 2 tabs.

  4. Heavy metals behavior during monocombustion and co-combustion of sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M.H.; Abelha, P.; Oliveira, J.F.S.; Cabrita, I.; Gulyurtlu, I. [DEECA, INETI, Lisbon (Portugal)

    2005-04-01

    This paper presents the study of the combustion of granular dry sewage sludge performed on a pilot fluidized bed system. The results of monocombustion of sludge and co-combustion with coal were compared with those of coal combustion for ash partitioning, the formation of gaseous pollutants, and heavy metals behavior. It was found that the mineral matter of sludge was essentially retained as bottom ash. The production of fine ash was small during the monocombustion but was high during co-combustion due to the tendency of coal to produce fine ash, which also contained unburned char. The degree of heavy metal volatilization was found to be slightly higher during co-combustion than in monocombustion; however, most of the metals were retained in the ash and their emissions were found to be below the regulated levels. Hg was completely volatilized. However, during combustion trials involving coal, Hg was captured in the cyclone ash at temperatures below 300{sup o}C. During sludge monocombustion the retention of Hg in cyclone ash containing low loss on ignition (LOI) was not enough to decrease emissions below the EU regulated levels; hence, it is necessary to install dedicated flue gas treatment for Hg removal. The leachability and ecotoxicity of sludge and ash were also compared with the new regulatory limits for landfill disposal in the European Union (EU).

  5. Co-Combustion of Animal Waste in a Commercial Waste-to-Energy BFB Boiler

    Directory of Open Access Journals (Sweden)

    Farzad Moradian

    2013-11-01

    Full Text Available Co-combustion of animal waste, in waste-to-energy boilers, is considered a method to produce both heat and power and to dispose of possibly infected animal wastes. This research conducted full-scale combustion tests to identify the impact of changed fuel composition on a fluidized-bed boiler. The impact was characterized by analyzing the deposit formation rate, deposit composition, ash composition, and emissions. Two combustion tests, denoted the reference case and animal waste case, were performed based on different fuel mixes. In the reference case, a normal solid waste fuel mix was combusted in the boiler, containing sorted industry and household waste. In the animal waste case, 20 wt% animal waste was added to the reference fuel mix. The collected samples, comprising sampling probe deposits, fuel mixes, bed ash, return sand, boiler ash, cyclone ash and filter ash, were analyzed using chemical fractionation, SEM-EDX and XRD. The results indicate decreased deposit formation due to animal waste co-combustion. SEM-EDX and chemical fractionation identified higher concentrations of P, Ca, S, and Cl in the bed materials in the animal waste case. Moreover, the risk of bed agglomeration was lower in the animal waste case and also a decreased rate of NOx and SO2 emissions were observed.

  6. Pre-combustion capture of carbon dioxide in a fixed bed reactor using the clathrate hydrate process

    International Nuclear Information System (INIS)

    Babu, Ponnivalavan; Kumar, Rajnish; Linga, Praveen

    2013-01-01

    Hydrate based gas separation (HBGS) process with silica sand and silica gel as contact medium was employed to capture CO 2 from fuel gas mixture. Gas uptake measurement at three different pressures (7.5, 8.5 and 9.0 MPa) and 274.15 K were conducted for hydrate formation kinetics and overall conversion of water to hydrate, rate of hydrate formation were determined. Water conversion of up to 36% was achieved with silica sand bed compared to 13% conversion in the silica gel bed. Effect of driving force on the rate of hydrate formation and gas consumption was significant in silica sand bed whereas it was found to be insignificant in silica gel bed. Hydrate dissociation experiments by thermal stimulation (at constant pressure) alone and a combination of depressurization and thermal stimulation were carried out for complete recovery of the hydrated gas. A driving force of 23 K was found to be sufficient to recover all the hydrated gas within 1 h. This study indicates that silica sand can be an effective porous media for separation of CO 2 from fuel gas when compared to silica gel. - Highlights: ► The clathrate process for pre-combustion capture of carbon dioxide in a novel fixed bed reactor is presented. ► Performance of two contact media (silica gel and silica sand) was investigated. ► Water to hydrate conversion was higher in a silica sand column. ► A pressure reduction and thermal stimulation approach is presented for a complete recovery of the hydrated gas

  7. Thermal and mechanical behaviour of oxygen carrier materials for chemical looping combustion in a packed bed reactor

    International Nuclear Information System (INIS)

    Jacobs, M.; Van Noyen, J.; Larring, Y.; Mccann, M.; Pishahang, M.; Amini, S.; Ortiz, M.; Galluci, F.; Sint-Annaland, M.V.; Tournigant, D.; Louradour, E.; Snijkers, F.

    2015-01-01

    Highlights: • Ilmenite-based oxygen carriers were developed for packed-bed chemical looping. • Addition of Mn_2O_3 increased mechanical strength and microstructure of the carriers. • Oxygen carriers were able to withstand creep and thermal cycling up to 1200 °C. • Ilmenite-based granules are a promising shape for packed-bed reactor conditions. - Abstract: Chemical looping combustion (CLC) is a promising carbon capture technology where cyclic reduction and oxidation of a metallic oxide, which acts as a solid oxygen carrier, takes place. With this system, direct contact between air and fuel can be avoided, and so, a concentrated CO_2 stream is generated after condensation of the water in the exit gas stream. An interesting reactor system for CLC is a packed bed reactor as it can have a higher efficiency compared to a fluidized bed concept, but it requires other types of oxygen carrier particles. The particles must be larger to avoid a large pressure drop in the reactor and they must be mechanically strong to withstand the severe reactor conditions. Therefore, oxygen carriers in the shape of granules and based on the mineral ilmenite were subjected to thermal cycling and creep tests. The mechanical strength of the granules before and after testing was investigated by crush tests. In addition, the microstructure of these oxygen particles was studied to understand the relationship between the physical properties and the mechanical performance. It was found that the granules are a promising shape for a packed bed reactor as no severe degradation in strength was noticed upon thermal cycling and creep testing. Especially, the addition of Mn_2O_3 to the ilmenite, which leads to the formation of an iron–manganese oxide, seems to results in stronger granules than the other ilmenite-based granules.

  8. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 2: Evaluation of ash materials as phosphorus fertilizer.

    Science.gov (United States)

    Thomsen, Tobias Pape; Hauggaard-Nielsen, Henrik; Gøbel, Benny; Stoholm, Peder; Ahrenfeldt, Jesper; Henriksen, Ulrik B; Müller-Stöver, Dorette Sophie

    2017-08-01

    The study is part 2 of 2 in an investigation of gasification and co-gasification of municipal sewage sludge in low temperature gasifiers. In this work, solid residuals from thermal gasification and co-gasification of municipal sewage sludge were investigated for their potential use as fertilizer. Ashes from five different low temperature circulating fluidized bed (LT-CFB) gasification campaigns including two mono-sludge campaigns, two sludge/straw mixed fuels campaigns and a straw reference campaign were compared. Experiments were conducted on two different LT-CFBs with thermal capacities of 100kW and 6MW, respectively. The assessment included: (i) Elemental composition and recovery of key elements and heavy metals; (ii) content of total carbon (C) and total nitrogen (N); (iii) pH; (iv) water extractability of phosphorus after incubation in soil; and (v) plant phosphorus response measured in a pot experiment with the most promising ash material. Co-gasification of straw and sludge in LT-CFB gasifiers produced ashes with a high content of recalcitrant C, phosphorus (P) and potassium (K), a low content of heavy metals (especially cadmium) and an improved plant P availability compared to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottom ashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded that LT-CFB gasification and co-gasification is a highly effective way to purify and sanitize sewage sludge for subsequent use in agricultural systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Effect of Additives and Fuel Blending on Emissions and Ash-Related Problems from Small-Scale Combustion of Reed Canary Grass

    Directory of Open Access Journals (Sweden)

    Sébastien Fournel

    2015-07-01

    Full Text Available Agricultural producers are interested in using biomass available on farms to substitute fossil fuels for heat production. However, energy crops like reed canary grass contain high nitrogen (N, sulfur (S, potassium (K and other ash-forming elements which lead to increased emissions of gases and particulate matter (PM and ash-related operational problems (e.g., melting during combustion. To address these problematic behaviors, reed canary grass was blended with wood (50 wt% and fuel additives (3 wt% such as aluminum silicates (sewage sludge, calcium (limestone and sulfur (lignosulfonate based additives. When burned in a top-feed pellet boiler (29 kW, the four blends resulted in a 17%–29% decrease of PM concentrations compared to pure reed canary grass probably because of a reduction of K release to flue gas. Nitrogen oxides (NOx and sulfur dioxide (SO2 emissions varied according to fuel N and S contents. This explains the lower NOx and SO2 levels obtained with wood based products and the higher SO2 generation with the grass/lignosulfonate blend. The proportion of clinkers found in combustion ash was greatly lessened (27%–98% with the use of additives, except for lignosulfonate. The positive effects of some additives may allow agricultural fuels to become viable alternatives.

  10. Assessing the effects of FBC ash treatments of metal-contaminated soils using life history traits and metal bioaccumulation analysis of the earthworm Eisenia andrei

    Energy Technology Data Exchange (ETDEWEB)

    Grumiaux, F.; Demuynck, S.; Schikorski, D.; Lemiere, S.; Lepretre, A. [Universite Lille Nord de France, Villeneuve Dascq (France)

    2010-03-15

    Earthworms (Eisenia andrei) were exposed, in controlled conditions, to metal-contaminated soils previously treated in situ with two types of fluidized bed combustion ashes. Effects on this species were determined by life history traits analysis. Metal immobilizing efficiency of ashes was indicated by metal bioaccumulation. Ashes-treated soils reduced worm mortality compared to the untreated soil. However, these ashes reduced both cocoon hatching success and hatchlings numbers compared to the untreated soil. In addition, sulfo-calcical ashes reduced or delayed worm maturity and lowered cocoon production compared to silico-alumineous ones. Metal immobilizing efficiency of ashes was demonstrated for Zn, Cu and to a lesser extent Pb. Only silico-alumineous ashes reduced Cd bioaccumulation, although Cd was still bioconcentrated. Thus, although ash additions to metal-contaminated soils may help in immobilizing metals, their use might result, depending on the chemical nature of ashes, to severe detrimental effects on earthworm reproduction with possible long term consequences to populations.

  11. Thermal co-treatment of combustible hazardous waste and waste incineration fly ash in a rotary kiln.

    Science.gov (United States)

    Huber, Florian; Blasenbauer, Dominik; Mallow, Ole; Lederer, Jakob; Winter, Franz; Fellner, Johann

    2016-12-01

    As current disposal practices for municipal solid waste incineration (MSWI) fly ash are either associated with significant costs or negative environmental impacts, an alternative treatment was investigated in a field scale experiment. Thereto, two rotary kilns were fed with hazardous waste, and moistened MSWI fly ash (water content of 23%) was added to the fuel of one kiln with a ratio of 169kg/Mg hazardous waste for 54h and 300kg/Mg hazardous waste for 48h while the other kiln was used as a reference. It was shown that the vast majority (>90%) of the inserted MSWI fly ash was transferred to the bottom ash of the rotary kiln. This bottom ash complied with the legal limits for non-hazardous waste landfills, thereby demonstrating the potential of the investigated method to transfer hazardous waste (MSWI fly ash) into non-hazardous waste (bottom ash). The results of a simple mixing test (MSWI fly ash and rotary kiln bottom ash have been mixed accordingly without thermal treatment) revealed that the observed transformation of hazardous MSWI fly ash into non-hazardous bottom ash during thermal co-treatment cannot be referred to dilution, as the mixture did not comply with legal limits for non-hazardous waste landfills. For the newly generated fly ash of the kiln, an increase in the concentration of Cd, K and Pb by 54%, 57% and 22%, respectively, was observed. In general, the operation of the rotary kiln was not impaired by the MSWI fly ash addition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Steam gasification of Bulmer coal in the presence of lignite ash

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, A.; Furimsky, E.

    1986-01-01

    Steam gasification of blends prepared from Balmer coal and the ash from combustion of Onakawana lignite was performed in a fixed bed reactor. The blends were prepared by co-slurrying followed by drying. In the presence of 20 wt% ash the gasification rate doubled at 830 and 930 C. Direct blending of coal and lignite resulted in an overall increase in carbon conversion at 830 C but had no effect at 930 C. 5 refs.

  13. Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic

    International Nuclear Information System (INIS)

    Valavanidis, Athanasios; Iliopoulos, Nikiforos; Gotsis, George; Fiotakis, Konstantinos

    2008-01-01

    The production and use of polymeric materials worldwide has reached levels of 150 million tonnes per year, and the majority of plastic materials are discarded in waste landfills where are burned generating toxic emissions. In the present study we conducted laboratory experiments for batch combustion/burning of commercial polymeric materials, simulating conditions of open fire combustion, with the purpose to analyze their emissions for chemical characteristics of toxicological importance. We used common types of plastic materials: poly(vinyl chloride) (PVC), low and high density poly(ethylene) (LDPE, HDPE), poly(styrene) (PS), poly(propylene) (PP) and poly(ethylene terephthalate) (PET). Samples of particulate smoke (soot) collected on filters and residue solid ash produced by controlled burning conditions at 600-750 deg. C are used for analysis. Emissions of particulate matter, persistent free radicals embedded in the carbonaceous polymeric matrix, heavy metals, other elements and PAHs were determined in both types of samples. Results showed that all plastics burned easily generating charred residue solid ash and black airborne particulate smoke. Persistent carbon- and oxygen-centered radicals, known for their toxic effects in inhalable airborne particles, were detected in both particulate smoke emissions and residue solid ash. Concentrations of heavy metals and other elements (determined by Inductively Coupled Plasma Emission Spectrometry, ICP, method) were measured in the airborne soot and residue ash. Toxic heavy metals, such as Pb, Zn, Cr, Ni, and Cd were relatively at were found at low concentrations. High concentrations were found for some lithophilic elements, such as Na, Ca, Mg, Si and Al in particulate soot and residue solid ash. Measurements of PAHs showed that low molecular weight PAHs were at higher concentrations in the airborne particulate soot than in the residue solid ash for all types of plastic. Higher-ringed PAHs were detected at higher

  14. Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic.

    Science.gov (United States)

    Valavanidis, Athanasios; Iliopoulos, Nikiforos; Gotsis, George; Fiotakis, Konstantinos

    2008-08-15

    The production and use of polymeric materials worldwide has reached levels of 150 million tonnes per year, and the majority of plastic materials are discarded in waste landfills where are burned generating toxic emissions. In the present study we conducted laboratory experiments for batch combustion/burning of commercial polymeric materials, simulating conditions of open fire combustion, with the purpose to analyze their emissions for chemical characteristics of toxicological importance. We used common types of plastic materials: poly(vinyl chloride) (PVC), low and high density poly(ethylene) (LDPE, HDPE), poly(styrene) (PS), poly(propylene) (PP) and poly(ethylene terephthalate) (PET). Samples of particulate smoke (soot) collected on filters and residue solid ash produced by controlled burning conditions at 600-750 degrees C are used for analysis. Emissions of particulate matter, persistent free radicals embedded in the carbonaceous polymeric matrix, heavy metals, other elements and PAHs were determined in both types of samples. Results showed that all plastics burned easily generating charred residue solid ash and black airborne particulate smoke. Persistent carbon- and oxygen-centered radicals, known for their toxic effects in inhalable airborne particles, were detected in both particulate smoke emissions and residue solid ash. Concentrations of heavy metals and other elements (determined by Inductively Coupled Plasma Emission Spectrometry, ICP, method) were measured in the airborne soot and residue ash. Toxic heavy metals, such as Pb, Zn, Cr, Ni, and Cd were relatively at were found at low concentrations. High concentrations were found for some lithophilic elements, such as Na, Ca, Mg, Si and Al in particulate soot and residue solid ash. Measurements of PAHs showed that low molecular weight PAHs were at higher concentrations in the airborne particulate soot than in the residue solid ash for all types of plastic. Higher-ringed PAHs were detected at higher

  15. Gaseous emissions in pressurized fluidized-bed combustion: Analysis and summary of the pilot experiments

    International Nuclear Information System (INIS)

    Korpela, T.; Hippinen, I.

    1995-01-01

    The project connects the experimental data from the projects of pressurised fluidized-bed technology by HUT/EVO. The research objectives are behaviour of sulphur absorbents and reduction of sulphur dioxide emissions, reduction of nitrogen oxide emissions, release of vapour-phase alkali metals and carbon monoxide emissions. Optimal process conditions in relation to minimising the emissions are clarified

  16. Bottom ash from fluidising bed boilers as filler material in district heating pipe culverts. Chemical and geotechnical characterisation; Pannsand som kringfyllnadsmaterial foer fjaerrvaermeroergravar. Kemisk och geoteknisk karaktaerisering av fluidbaeddsand

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Roger; Rogbeck, Jan; Suer, Pascal

    2004-01-01

    Bottom ashes from fluid bed boilers have been characterised, both geotechnically and chemically, in order to investigate the possibility to use them as filler material in district heating pipe culverts. Bottom ashes from both biofuel boilers and waste boilers are represented in this project. The companies which ashes have been characterised are Sundsvall Energi AB, Sydkraft OestVaerme AB, Sydkraft MaelarVaerme AB, Eskilstuna Miljoe och Energi, Stora Enso Fors, Soederenergi and Fortum Vaerme. A total of ten ashes have been analysed where three ashes originates from Sundsvall Energi AB, two from Sydkraft OestVaerme AB and one from the each of the remaining companies. The chemical analyses have been performed both on fresh ashes and on ashes aged for three months. The geotechnical analyses performed are grain size distribution, packing abilities and permeability. Chemical analyses performed are total content, available content, leaching tests (leaching both by shaking method and column procedure) and organic analyses (PAH, EOX, TOC, dioxin and fenol). The geotechnical analyses show that the ashes fulfils the demands that are put on the filler material used in district heating pipe culverts. When using the ashes in applications, light compaction should be performed due to the risk of crushing the material which may cause an increased amount of fine material. The leachability of fine material is larger than for coarse material. The ashes are relatively insensitive to precipitation. Bio fuel based bottom ashes have a lower content of environmental affecting substances than waste fuel based ashes. This is also shown in the leaching analyses. The leaching water from fresh ashes contains a higher concentration of leachable components than aged ashes. When aged the pH in the ashes decreases due to carbon uptake and hydration and this makes metals as Pb, Cu, Cr and Zn less mobile. On the other hand, an increase in leachability of Sb, Mo and SO{sub 4} is shown when the ashes

  17. Co-sintering of treated APC-residues with bottom ash

    DEFF Research Database (Denmark)

    Jensen, Dorthe Lærke; Bergfeldt, Britta; Vehlow, Jürgen

    2001-01-01

    the influence of co-sintering of Ferrox products with bottom ashes on the quality of the residues and the effects on the combustion process. Only few elements showed higher concentrations in the bottom ashes of these co-combustion tests compared to reference tests. No significant effect on the leaching......Air pollution control residues stabilised by means of the Ferrox process can be sager disposed of due to lower contents of soluble salts and lesssoluble heavy metals stabilised in iron oxides. Co-combustion tests in the Karlsruhe test incinerator TAMARA were carried out in order to investigate...... behaviour of the bottom ashes could be found. During the co-combustion process an increase in SO2 concentrations in the raw gas and slightly lower temperatures in the fuel bed could be observed....

  18. Experimental study of gas combustion fluidized bed and radiation contribution to heat transfer inside the bed. Gas nensho ryudoso to sono sonai netsudentatsu ni okeru fukusha no kiyo ni tsuite no jikkenteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Y; Takahashi, S [Mechanical Engineering Lab., Tsukuba, Ibaraki (Japan); Maki, H [Science Univ. of Tokyo, Noda, Chiba (Japan). Faculty of Science and Technology

    1992-11-25

    Fluidized bed as a coal combustion boiler has a practical application, but, there is not an example of which gas like helium as a cooling medium flow in a thin tube with diameter of 6 mm like a stirling engine and necessary data for selecting the medium of fluidized bed and estimating the heat transfer coefficient. Specially, it is difficult to correctly estimate the radiation effect concerned with the heat transfer coefficient in case of interposing the heat transfer tube at 800 [degree]C in the high-temperature fluidized bed at more than 900 [degree]C. Therefore, for investigating the thermal characteristics when the temperature of pipe itself is at high temperature, in the gas combustion fluidized bed in which alumina particle as fluidized medium is filled, the cooling tubes by using carbonic acid gas as a cooling medium was interposed, heat transfer coefficient was measured, radiation effect was clarified by experiment, and characteristics of the gas combustion and of the exhaust gas of fluidized bed when gas is used for a fuel was investigated. 13 refs., 12 figs., 1 tab.

  19. Importance of spinel reaction kinetics in packed-bed chemical looping combustion using a CuO/Al2O3 oxygen carrier

    NARCIS (Netherlands)

    San Pio, M.A.; Sabatino, F.; Gallucci, F.; van Sint Annaland, M.

    2018-01-01

    Chemical looping combustion is especially competitive for electrical power generation with integrated CO2 capture when it is operated at high temperatures (1000–1200 °C) and high pressures (15 bar or higher). For these demanding conditions, dynamically operated packed bed reactors have been

  20. Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

    KAUST Repository

    Zhao, Zhenlong

    2013-01-17

    Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two-part series, a new rotary reactor concept for gas-fueled CLC is proposed and analyzed. In part 1, the detailed configuration of the rotary reactor is described. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet and exit. Two purging sectors are used to avoid the mixing between the fuel stream and the air stream. The rotary wheel consists of a large number of channels with copper oxide coated on the inner surface of the channels. The support material is boron nitride, which has high specific heat and thermal conductivity. Gas flows through the reactor at elevated pressure, and it is heated to a high temperature by fuel combustion. Typical design parameters for a thermal capacity of 1 MW have been proposed, and a simplified model is developed to predict the performances of the reactor. The potential drawbacks of the rotary reactor are also discussed. © 2012 American Chemical Society.

  1. Nitrogen evolution during the co-combustion of hydrothermally treated municipal solid waste and coal in a bubbling fluidized bed.

    Science.gov (United States)

    Lu, Liang; Jin, Yuqi; Liu, Hongmei; Ma, Xiaojun; Yoshikawa, Kunio

    2014-01-01

    Nitrogen evolution was studied during the co-combustion of hydrothermally treated municipal solid wastes (HT MSW) and coal in a bubbling fluidized bed (BFB). HT MSW blending ratios as 10%, 20% and 30% (wt.%) were selected and tested at 700, 800, 900 °C. Emissions of NO and N2O from blends were measured and compared with the results of mono-combustion trials. Moreover, concentrations of precursors like NH3 and HCN were also quantified. The results are summarized as follows: NO emissions were predominant in all the cases, which rose with increasing temperature. The blending of HT MSW contributed to the NO reduction. N2O emissions decreased with temperature rising and the blending of HT MSW also presented positive effects. At 30% HT MSW addition, both NO and N2O emissions showed the lowest values (391.85 ppm and 55.33 ppm, respectively at 900 °C). For the precursors, more HCN was detected than NH3 and both played important roles on the gas side nitrogen evolution. Copyright © 2013. Published by Elsevier Ltd.

  2. An Experimental Study on Axial Temperature Distribution of Combustion of Dewatered Poultry Sludge in Fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    Abbas A.H.

    2016-01-01

    Full Text Available A laboratory scale bubbling fluidized bed combustor was designed and fabricated to study the combustion of dewatered poultry sludge at different operational parameters. This paper present a study on the influence of equivalent ratio, secondary to primary air ratio and the fuel feed rate on the temperature distribution along the combustor. The equivalent ratio has been changed between 0.8 to 1.4% under poultry sludge feed rate of 10 kg/h and from 0.8 to 1 under poultry sludge feed rate of 15 kg/h. The secondary to primary air ratio was varied from 0.1 to 0.5 at 0.65 m injection height and 1.25 equivalent ratio. The results showed that these factors had a significant influence on the combustion characteristics of poultry sludge. The temperature distribution along the combustor was found to be strongly dependent on the fuel feed rate and the equivalent ratio and it increased when these two factors increased. However, the secondary air ratio increased the temperature in the lower region of the combustor while no significant effect was observed at the upper region of the combustor. The results suggested that the poultry sludge can be used as a fuel with high thermal combustor efficiency.

  3. Fluidized bed combustion research and development in Sweden: A historical survey

    Directory of Open Access Journals (Sweden)

    Leckner Bo.

    2003-01-01

    Full Text Available A survey is made on research and development related to fluidized bed boilers in Sweden during the past two decades, where several Swedish enterprises took part: Generator, Götaverken, Stal Laval (ABB Carbon and Studsvik. Chalmers University of Technology contributed in the field of research related to emissions, heat transfer and fluid dynamics, and some results from this activity are briefly summarized.

  4. Experimental findings on thermal use of residues and biofuels in circulating fluidized bed combustion systems; Experimentelle Ergebnisse zur thermischen Nutzung von Rest- und Biobrennstoffen in zirkulierenden Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W.; Brunne, T.; Girndt, H. [Technische Univ. Dresden (Germany); Albrecht, J. [Lurgi Lentjes Babcock, Frankfurt am Main (Germany); Youssef, M. [Minia Univ. (Egypt)

    1996-12-31

    The energy Engineering Institute of Dresden Technical University investigated the combustion and emission characteristics of a number of combustion systems, including a circulating fluidized bed system with a capacity of 0.3 MW{sub th}. Egypt`s sugar cane industry produces large volumes of bagasse. The conbustion and emission characteristics of this biofuel in a circulating fludized bed combustion systems were investigated in a joint research project of the University of Minia and Dresden Technical University. (orig.) [Deutsch] Am Institut fuer Energietechnik der TU Dresden wird das Verbrennungs- und Emissionsverhalten verschiedenster Brennstoffe in unterschiedlichen Feuerungssystemen untersucht. Neben anderen Pilotanlagen steht eine zirkulierende Wirbelschichtfeuerung (ZWFS) mit einer Leistung von 0.3 MW{sub th} zur Verfuegung. In der Zuckerrohrindustrie Aegyptens fallen grosse Mengen von Bagasse an. In einer gemeinsamen Forschungsarbeit zwischen der Universitaet Minia und der TU Dresden sollte das Verbrennungs- und Emissionsverhalten dieses Biobrennstoffes in einer ZWSF untersucht werden. (orig)

  5. Experimental findings on thermal use of residues and biofuels in circulating fluidized bed combustion systems; Experimentelle Ergebnisse zur thermischen Nutzung von Rest- und Biobrennstoffen in zirkulierenden Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W; Brunne, T; Girndt, H [Technische Univ. Dresden (Germany); Albrecht, J [Lurgi Lentjes Babcock, Frankfurt am Main (Germany); Youssef, M [Minia Univ. (Egypt)

    1997-12-31

    The energy Engineering Institute of Dresden Technical University investigated the combustion and emission characteristics of a number of combustion systems, including a circulating fluidized bed system with a capacity of 0.3 MW{sub th}. Egypt`s sugar cane industry produces large volumes of bagasse. The conbustion and emission characteristics of this biofuel in a circulating fludized bed combustion systems were investigated in a joint research project of the University of Minia and Dresden Technical University. (orig.) [Deutsch] Am Institut fuer Energietechnik der TU Dresden wird das Verbrennungs- und Emissionsverhalten verschiedenster Brennstoffe in unterschiedlichen Feuerungssystemen untersucht. Neben anderen Pilotanlagen steht eine zirkulierende Wirbelschichtfeuerung (ZWFS) mit einer Leistung von 0.3 MW{sub th} zur Verfuegung. In der Zuckerrohrindustrie Aegyptens fallen grosse Mengen von Bagasse an. In einer gemeinsamen Forschungsarbeit zwischen der Universitaet Minia und der TU Dresden sollte das Verbrennungs- und Emissionsverhalten dieses Biobrennstoffes in einer ZWSF untersucht werden. (orig)

  6. Down-flow moving-bed gasifier with catalyst recycle

    Science.gov (United States)

    Halow, John S.

    1999-01-01

    The gasification of coal and other carbonaceous materials by an endothermic gasification reaction is achieved in the presence of a catalyst in a down-flow, moving-bed gasifier. Catalyst is removed along with ash from the gasifier and is then sufficiently heated in a riser/burner by the combustion of residual carbon in the ash to volatilize the catalyst. This volatilized catalyst is returned to the gasifier where it uniformly contacts and condenses on the carbonaceous material. Also, the hot gaseous combustion products resulting from the combustion of the carbon in the ash along with excess air are introduced into the gasifier for providing heat energy used in the endothermic reaction.

  7. 3D Numerical Study of Multiphase Counter-Current Flow within a Packed Bed for Post Combustion Carbon Dioxide Capture

    Directory of Open Access Journals (Sweden)

    Li Yang

    2018-06-01

    Full Text Available The hydrodynamics within counter-current flow packed beds is of vital importance to provide insight into the design and operational parameters that may impact reactor and reaction efficiencies in processes used for post combustion CO2 capture. However, the multiphase counter-current flows in random packing used in these processes are complicated to visualize. Hence, this work aimed at developing a computational fluid dynamics (CFD model to study more precisely the complex details of flow inside a packed bed. The simulation results clearly demonstrated the development of, and changes in, liquid distributions, wetted areas, and film thickness under various gas and liquid flow rates. An increase in values of the We number led to a more uniform liquid distribution, and the flow patterns changed from droplet flow to film flow and trickle flow as the We number was increased. In contrast, an increase in gas flow rate had no significant effect on the wetted areas and liquid holdup. It was also determined that the number of liquid inlets affected flow behavior, and the liquid surface tension had an insignificant influence on pressure drop or liquid holdup; however, lower surface tension provided a larger wetted area and a thinner film. An experimental study, performed to enable comparisons between experimentally measured pressure drops and simulation-determined pressure drops, showed close correspondence and similar trends between the experimental data and the simulation data; hence, it was concluded that the simulation model was validated and could reasonably predict flow dynamics within a counter-current flow packed bed.

  8. Experimental studies of the influence of fuel properties and operational conditions on stoking when combusting fuels in a fixed-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Arias, Fabiana; Kolb, T.; Seifert, H.; Gehrmann, Hans-Joachim [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Technical Chemistry (ITC)

    2013-09-01

    Besides from knowledge about pollutant emission, knowledge of the combustion behavior of fuels plays a major role in the operation and optimization of combustion plants for waste and biomass. If the fuel is exchanged partly or completely in existing or newly designed grate-type combustion plants, adaptation of technical parameters is usually based on purely empirical studies. In the KLEAA fixed-bed reactor of KIT, Institute for Technical Chemistry (ITC), quantitative data on the combustion behavior can be determined from experimental investigations on the laboratory scale. Based on the characteristics obtained, the combustion behavior on a continuous grate can be estimated, This estimation is based on the assumption that no back mixing of the fuel occurs on the grate. Depending on the type of grate, however, stoking and back mixing play an important role. To improve the quality of the characteristics determined in KLEAA and enhance their transferability to the continuous process, it is necessary to determine the influence of fuel properties and operation conditions on stoking. Work is aimed at further developing the characteristics model taking into account a stoking factor describing the combustion behavior of a non-stoked fixed bed compared to a stoked fixed bed. The main task is to make a systematic study of the major parameters influencing stoking (e.g. stroke length, stroke frequency, geometry of the stoking unit, and fuel properties) in a fixed-bed reactor. The results shall be presented in the form of a semi-empirical equation. It is recommended to first study a model fuel, whose fuel properties are defined exactly and can be adjusted variably. Then, a stoking factor shall be derived from the studies. Possibly, a dimension analysis may be helpful. Finally, the results obtained are to be verified for residue-derived fuel. (orig.)

  9. HTR combustion head end comparison of the shaft furnace and fluidized bed processes

    Energy Technology Data Exchange (ETDEWEB)

    Boehnert, R.; Kaiser, G.; Pirk, H.; Tillessen, U.

    1975-01-15

    Two methods are described for the combustion of the graphite of HTR fuel elements, a sufficient description of the principles being given to permit an understanding of the processes. The present state of the technology of the two processes is then compared on the basis of the results obtained at Gulf General Atomic. Finally, the possibilities of further development are examined using a pilot plant designed to deliver a reactor power of 7000 MWe as the basis. The present report is a collection of facts. It contains neither an evaluation nor a recommendation. A summarized comparison of the state of the technology and the possibilities of development is given in tabular form.

  10. Studies on nitrogen oxides (NO{sub x} and N{sub 2}O) in pressurized fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Lu Yong

    1998-09-01

    This thesis describes the experimental studies of nitrogen oxide (NO, NO{sub 2}, N{sub 2}O) emissions in pressurized fluidized bed combustion (PFBC). In the first part of the thesis the background and the objectives of this study are introduced. The second part summarizes the fundamental knowledge about the formation and destruction of nitrogen oxides in coal combustion, particularly in the conditions of PFBC. The instrumentation of test facilities, measurement and data analysis is described in the third part. Then the most important experimental results follow in the next parts. The forth part describes the results from a PFBC test rig and an empirical modelling for predicting the emissions of NO{sub x} and N{sub 2}O. Finally, the fundamental work on coal combustion and fuel nitrogen conversion in a PFBC batch reactor is presented. These studies clearly confirm the potential of PFBC technology in the control nitrogen of oxide emissions. The research in the test rig was concentrated on determining the effects of process parameters on the emissions of nitrogen oxides with different fuels. Another objective was to examine the reduction of nitrogen oxides with the control methods in PFBC conditions, including ammonia injection and air staging combustion for reducing NO, and high temperature operations for reducing N{sub 2}0. The results indicate that pressurized operation suppresses the conversion of fuel-N to nitrogen oxides and favors with employing the reduction methods for further nitrogen oxide reduction, for instance the temperature window of NO reduction with ammonia injection has been found to be widened to even lower temperature range. Maximum reductions of 80-85 % with ammonia injection and 75-80 % with air staging combustion were achieved in the conditions examined. Considerably low emissions of N{sub 2}O (<7 ppm) were obtained in the tests of N{sub 2}O control, and thermal decomposition proved to be the laming pathway of N{sub 2}O destruction in PFBC. In

  11. Environmental Benefit Assessment for the Carbonation Process of Petroleum Coke Fly Ash in a Rotating Packed Bed.

    Science.gov (United States)

    Pei, Si-Lu; Pan, Shu-Yuan; Li, Ye-Mei; Chiang, Pen-Chi

    2017-09-19

    A high-gravity carbonation process was deployed at a petrochemical plant using petroleum coke fly ash and blowdown wastewater to simultaneously mineralized CO 2 and remove nitrogen oxides and particulate matters from the flue gas. With a high-gravity carbonation process, the CO 2 removal efficiency was found to be 95.6%, corresponding to a capture capacity of 600 kg CO 2 per day, at a gas flow rate of 1.47 m 3 /min under ambient temperature and pressure. Moreover, the removal efficiency of nitrogen oxides and particulate matters was 99.1% and 83.2%, respectively. After carbonation, the reacted fly ash was further utilized as supplementary cementitious materials in the blended cement mortar. The results indicated that cement with carbonated fly ash exhibited superior compressive strength (38.1 ± 2.5 MPa at 28 days in 5% substitution ratio) compared to the cement with fresh fly ash. Furthermore, the environmental benefits for the high-gravity carbonation process using fly ash were critically assessed. The energy consumption of the entire high-gravity carbonation ranged from 80 to 169 kWh/t-CO 2 (0.29-0.61 GJ/t-CO 2 ). Compared with the scenarios of business-as-usual and conventional carbon capture and storage plant, the economic benefit from the high-gravity carbonation process was approximately 90 and 74 USD per ton of CO 2 fixation, respectively.

  12. Combustion behaviour of Olive pruning/animal manure blends in a fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    Despina Vamvuka

    2017-09-01

    Both fuels burned mostly within the bed. The maximum temperature of animal manure was 50 °C lower than that of olive pruning, however efficiency was nearly 99%. CO emissions were low, SO2 emissions were negligible, whereas NOx emissions of blends exceeded legislation limits, when excess air ratio was over 1.4. Decreasing excess air from 50 to 30%, or reducing reactor loading, resulted in improved burnout. The optimum performance for the blends was achieved when the feed rate was 0.6 kg/h and excess air was 30%.

  13. Trace elements in coal ash

    Science.gov (United States)

    Deonarine, Amrika; Kolker, Allan; Doughten, Michael W.

    2015-01-01

    Coal ash is a residual waste product primarily produced by coal combustion for electric power generation. Coal ash includes fly ash, bottom ash, and flue-gas desulfurization products (at powerplants equipped with flue-gas desulfurization systems). Fly ash, the most common form of coal ash, is used in a range of products, especially construction materials. A new Environmental Protection Agency ruling upholds designation of coal ash as a non-hazardous waste under Subtitle D of the Resource Conservation and Recovery Act, allowing for the continued beneficial use of coal ash and also designating procedures and requirements for its storage.

  14. The comparative analysis of heat transfer efficiency in the conditions of formation of ash deposits in the boiler furnaces, with taking into account the crystallization of slag during combustion of coal and water-coal fuel

    Science.gov (United States)

    Salomatov, V. V.; Kuznetsov, G. V.; Syrodoy, S. V.

    2017-11-01

    The results of the numerical simulation of heat transfer from the combustion products of coal and coal-water fuels (CWF) to the internal environment. The mathematical simulation has been carried out on the sample of the pipe surfaces of the combustion chamber of the boiler unit. The change in the characteristics of heat transfer (change of thermochemical characteristics) in the conditions of formation of the ash deposits have been taken into account. According to the results of the numerical simulation, the comparative analysis of the efficiency of heat transfer has been carried out from the furnace environment to the inside pipe coolant (water, air, or water vapor) from the combustion of coal and coal-water fuels. It has been established that, in the initial period of the boiler unit operation during coal fuel combustion the efficiency of heat transfer from the combustion products of the internal environment is higher than when using CWF. The efficiency of heat transfer in CWF combustion conditions is more at large times (τ≥1.5 hours) of the boiler unit. A significant decrease in heat flux from the combustion products to the inside pipe coolant in the case of coal combustion compared to CWF has been found. It has been proved that this is due primarily to the fact that massive and strong ash deposits are formed during coal combustion.

  15. Investigation of flow behaviour of coat/ash particles in an advanced pressurised fluidized bed gasifier (APFBG) using radiotracer technique

    International Nuclear Information System (INIS)

    Pant, H.J.; Sharma, V.K.; Gursharan Singh; Vidhya Kamadu, M.; Prakash, S.G.; Krishanamoorthy, S.; Ramani, N.V.S.; Sonde, R.R.

    2004-01-01

    Knowledge of Residence Time Distribution (RTD), Mean Residence Time (MRT) and degree of backmixing of solid phase is important for efficient operation of the coal gasifier. Radiotracer technique was used for measure RTD of coal/ash particles in a pilot-scale gasifier and obtain the values of MRT and backmixing. Lanthanum 140 labeled coal (100 g) was used as a tracer. The tracer was instantaneously injected into the coal feed line and monitored at ash and gas outlets of the gasifier using collimated scintillation detectors. The measured RTD data were treated and MRTs of coal/ash particles were determined. The treated data were simulated using tank-in-series model. The simulation RTD data indicated good degree of mixing with minor bypassing/short-circulating of coal particles. The results of the investigation were found useful for scale-up of the gasification process. (author)

  16. Using X-ray methods to evaluate the combustion sulfur minerals and graphitic carbon in coals and ashes

    International Nuclear Information System (INIS)

    Wertz, D.L.; Collins, L.W.

    1988-01-01

    Coals are complex mixtures of vastly different materials whose combustion kinetics may well exhibit symbiotic effects. Although the sulfur oxide gases produced during the combustion of coals may have a variety of sources, they are frequently caused by the thermal degradation of inorganic minerals to produce ''acid rain''. Since many of the minerals involved either as reactants or products in coal combustion produce well defined x-ray power diffraction (XRPD) patterns, the fate of these minerals may be followed by measuring the XRPD patterns of combustion products. Coal 1368P, a coal with an unusually high pyrite (FeS/sub 2/) fraction, has been the subject materials in our investigations of the fate of the inorganic minerals during combustion. These studies include measuring the fate of pyrite and of graphitic carbon in coal 1368P under varying combustion conditions. The results discussed in this paper were obtained by standard XRPD methods

  17. The influence of temperature on limestone sulfation and attrition under fluidized bed combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Montagnaro, Fabio [Dipartimento di Chimica - Universita degli Studi di Napoli Federico II, Complesso Universitario del Monte di Sant' Angelo, 80126 Napoli (Italy); Salatino, Piero [Istituto di Ricerche sulla Combustione - CNR, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Dipartimento di Ingegneria Chimica - Universita degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Scala, Fabrizio [Istituto di Ricerche sulla Combustione - CNR, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy)

    2010-04-15

    The influence of temperature on attrition of two limestones during desulfurization in a fluidized bed reactor was investigated. Differences in the microstructure of the two limestones were reflected by a different thickness of the sulfate shell formed upon sulfation and by a different value of the ultimate calcium conversion degree. Particle attrition and fragmentation were fairly small under moderately bubbling fluidization conditions for both limestones. An increase of temperature from 850 C to 900 C led to an increase of the attrition rate, most likely because of a particle weakening effect caused by a faster CO{sub 2} evolution during calcination. This weakening effect, however, was not sufficiently strong to enhance particle fragmentation in the bed. The progress of sulfation, associated to the build-up of a hard sulfate shell around the particles, led in any case to a decrease of the extent of attrition. Sulfation at 900 C was less effective than at 850 C, and this was shown to be related to the porosimetric features of the different samples. (author)

  18. Clean utilization of high sulphur petroleum coke by circulating fluidized bed combustion (CFBC) in Romania

    International Nuclear Information System (INIS)

    Dragos, L.; Flueraru, C.; Girjoaba, M.

    1996-01-01

    The economic and environmental problems caused by inefficient utilization of residual high-sulphur petroleum coke resulted from oil cracking in Romania is discussed. A special research programme applying CFBC technology has been carried out in the Institute for Power Equipment, Bucharest. The results from both laboratory facilities and pilot plant are presented. The main operating conditions and parameters are pointed out. Data on quality and composition of petroleum coke, combustion efficiency, temperature range in different zones and flue gas composition at distinct operating loads are given. The results obtained will be used for innovative design of CFBC boilers based on petroleum coke. A project for implementing a CFBC boiler in one of the Romanian oil refineries is being developed. An analysis of technical and economic advantages of these boilers for energy generation is presented

  19. Analysis of Flue Gas Emission Data from Fluidized Bed Combustion Using Self-Organizing Maps

    Directory of Open Access Journals (Sweden)

    Mika Liukkonen

    2010-01-01

    Full Text Available Efficient combustion of fuels with lower emissions levels has become a demanding task in modern power plants, and new tools are needed to diagnose their energy production. The goals of the study were to find dependencies between process variables and the concentrations of gaseous emission components and to create multivariate nonlinear models describing their formation in the process. First, a generic process model was created by using a self-organizing map, which was clustered with the k-means algorithm to create subsets representing the different states of the process. Characteristically, these process states may include high- and low- load situations and transition states where the load is increased or decreased. Then emission models were constructed for both the entire process and for the process state of high boiler load. The main conclusion is that the methodology used is able to reveal such phenomena that occur within the process states and that could otherwise be difficult to observe.

  20. Research report of FY 1997 on the environmentally acceptable coal utilization system introduction support project. Demonstration project of circulating fluidized bed boiler (Jinzhou Coal-Thermal Power Corporation); 1997 nendo seika hokokusho (kankyo chowagata sekitan riyo system donyu shien jigyo). Junkan ryudosho boiler ni kakawaru jissho jigyo (Jinzhou netsuden sokoji)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    To verify the clean coal technology to be diffused in China and consolidate its diffusion basis, demonstration project of circulating fluidized bed boiler was conducted through the cooperation with China which is positive in its introduction. This report describes its characteristics. Coal and limestone are supplied in a lower part of combustion chamber, and are mixed with circulating ash by fluidized air for combustion. Densely fluidized bed the same as the bubbling fluidized bed is formed in the lower part of combustion chamber, which provides excellent stability in ignition and combustion. Particles including ash, char and limestone formed during the combustion are discharged into the cyclone through the convection heat transfer part at the outlet of combustion chamber with the combustion gas flow. Since the gas temperature is lowered to 400 to 500degC at the convection heat transfer part, troubles of the ash circulating system can be prevented. The combustion gas separated from ash at the cyclone is discharged through the heat exchanger and precipitator, and the collected ash is returned to the lower part of combustion chamber. In FY 1997, design, fabrication, procurement/inspection, field survey/meeting, survey of visitors/meeting, and education were carried out. 4 figs., 4 tabs.

  1. Effects of Temperature and Residence Time on the Emissions of PIC and Fine Particles during Fixed Bed Combustion of Conifer Stemwood Pellets

    Energy Technology Data Exchange (ETDEWEB)

    Boman, Christoffer; Lindmark, Fredrik; Oehman, Marcus; Nordin, Anders [Umeaa Univ. (Sweden). Energy Technology and Thermal Process Chemistry; Pettersson, Esbjoern [Energy Technology Centre, Piteaa (Sweden); Westerholm, Roger [Stockholm Univ., Arrhenius Laboratory (Sweden). Dept. of Analytical Chemistry

    2006-07-15

    The use of wood fuel Pellets has proved to be well suited for the small-scale market enabling controlled and efficient combustion with low emission of products of incomplete combustion (PIC). Still a potential for further emission reduction exists and a thorough understanding of the influence of combustion conditions on the emission characteristics of air pollutants like PAH and particulate matter (PM) is important. The objective was to determine the effects of temperature and residence time on the emission performance and characteristics with focus on hydrocarbons and PM during combustion of conifer stemwood Pellets in a laboratory fixed bed reactor (<5 kW). Temperature and residence time after the bed section were varied according to statistical experimental designs (650-970 deg C and 0.5-3.5 s) with the emission responses; CO, organic gaseous carbon, NO, 20 VOC compounds, 43 PAH compounds, PM{sub tot}, fine particle mass/count median diameter (MMD and CMD) and number concentration. Temperature was negatively correlated with the emissions of all studied PIC with limited effects of residence time. The PM{sub tot} emissions of 15-20 mg/MJ was in all cases dominated by fine (<1 {mu}m) particles of K, Na, S, Cl, C, O and Zn. Increased residence time resulted in increased fine particle sizes (i.e. MMD and CMD) and decreased number concentrations. The importance of high temperature (>850 deg C) in the bed zone with intensive, air rich and well mixed isothermal conditions for 0.5-1.0 s in the post combustion zone was illustrated for wood Pellets combustion with almost a total depletion of all studied PIC. The results emphasize the need for further verification studies and technology development work.

  2. Investigation of the potential of coal combustion fly ash for mineral sequestration of CO2 by accelerated carbonation

    International Nuclear Information System (INIS)

    Ukwattage, N.L.; Ranjith, P.G.; Wang, S.H.

    2013-01-01

    Mineral carbonation of alkaline waste materials is being studied extensively for its potential as a way of reducing the increased level of CO 2 in the atmosphere. Carbonation converts CO 2 into minerals which are stable over geological time scales. This process occurs naturally but slowly, and needs to be accelerated to offset the present rate of emissions from power plants and other emission sources. The present study attempts to identify the potential of coal fly ash as a source for carbon storage (sequestration) through ex-situ accelerated mineral carbonation. In the study, two operational parameters that could affect the reaction process were tested to investigate their effect on mineralization. Coal fly ash was mixed with water to different water-to-solid ratios and samples were carbonated in a pressure vessel at different initial CO 2 pressures. Temperature was kept constant at 40 °C. According to the results, one ton of Hazelwood fly ash could sequester 7.66 kg of CO 2 . The pressure of CO 2 inside the vessel has an effect on the rate of CO 2 uptake and the water-to-solid ratio affects the weight gain after the carbonation of fly ash. The results confirm the possibility of the manipulation of process parameters in enhancing the carbonation reaction. - Highlights: ► Mineral sequestration CO 2 by of coal fly ash is a slow process under ambient conditions. ► It can be accelerated by manipulating the process parameters inside a reactor. ► Initial CO 2 pressure and water to solid mixing ratio inside the reactor are two of those operational parameters. ► According to the test results higher CO 2 initial pressure gives higher on rates of CO 2 sequestration. ► Water to fly ash mixing ratio effect on amount of CO 2 sequestered into fly ash

  3. Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers

    International Nuclear Information System (INIS)

    Arenas, Celia; Leiva, Carlos; Vilches, Luis F.; Cifuentes, Héctor

    2013-01-01

    Highlights: • The particle size of bottom ash influenced the acoustic behavior of the barrier. • The best sound absorption coefficients were measured for larger particle sizes. • The maximum noise absorption is displaced to lower frequencies for higher thickness. • A noise barrier was designed with better properties than commercial products. • Recycling products from bottom ash no present leaching and radioactivity problems. - Abstract: The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk

  4. Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers

    Energy Technology Data Exchange (ETDEWEB)

    Arenas, Celia; Leiva, Carlos; Vilches, Luis F. [University of Seville, School of Industrial Engineering, Department of Chemical and Environmental Engineering, Camino de los Descubrimientos s/n, E-41092 Seville (Spain); Cifuentes, Héctor, E-mail: bulte@us.es [University of Seville, School of Industrial Engineering, Continuum Mechanics and Structural Analysis Department, Camino de los Descubrimientos s/n, E-41092 Seville (Spain)

    2013-11-15

    Highlights: • The particle size of bottom ash influenced the acoustic behavior of the barrier. • The best sound absorption coefficients were measured for larger particle sizes. • The maximum noise absorption is displaced to lower frequencies for higher thickness. • A noise barrier was designed with better properties than commercial products. • Recycling products from bottom ash no present leaching and radioactivity problems. - Abstract: The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk.

  5. Thermal disposal of sewage sludges by fluidised bed combustion with low emissions of pollutants. Thermische Entsorgung kommunaler Klaerschlaemme durch schadstoffarme Verbrennung in der Wirbelschicht

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, B. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik); Lindau, S. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik); Busse, U. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik)

    1992-04-01

    The volume of sludge from the sewage treatment represents the largest problem in the waste management in Germany recently. The thermal treatment is inevitable for the solution of the problem. The fluidised bed combustion is suitable for a very good usability of sewage sludge. Experimental investigations carried out in a stationary fluidised bed in laboratory scale. The emissions of gaseous air pollutants are influenced by the properties of the sludge and the parameters of the process. The dependence of the formation and the reactions of the pollutants from various parameters are analysed and judged. (orig.)

  6. Gaseous emissions in pressurised fluidised-bed combustion. Analysis and summary of the pilot experiments; Kaasumaiset paeaestoet paineistetussa leijukerrospoltossa. Koetulosten kaesittely ja yhteenveto

    Energy Technology Data Exchange (ETDEWEB)

    Korpela, T.; Hippinen, I.; Konkola, M. [Helsinki Univ. of Technology, Espoo (Finland)

    1996-12-01

    The influence of operating conditions on gaseous emissions in pressurised fluidised-bed combustion have been studied. The research objectives have been behaviour of sulphur absorbents and reduction of sulphur dioxide emissions, reduction of nitrogen oxide emissions, release of vapour-phase alkalimetals and carbon monoxide emissions. The sulphur capture capacities of calcium-based sorbents under PFBC conditions have been studied at a pressurised fluidised-bed reactor and at a pressurised thermogravimetric apparatus. The project has also connected results of the experimental PFBC at HUT/EVO. (author)

  7. Why and how to make a REACH registration of combustion ash; Moejligheter vid REACH-registrering av energiaskor

    Energy Technology Data Exchange (ETDEWEB)

    Loevgren, Linnea; Wik, Ola

    2009-10-15

    The new chemical regulation, REACH (1997/2006/EC), Registration, Evaluation, Authorization and restriction of Chemicals, took effect the 1st of June 2007. The background to this report was the introduction of REACH and the difficulties to understand the implications for ash. The most important consequence of REACH is that all chemical substances that are manufactured, handled and used above one tonne per annum per legal entity shall be registered according to this regulation. The registration includes specifying the chemical, physical, toxicity and ecotoxicity properties of the substance and risk assessing the identified areas of use. The report describes the use of ash in connection to the waste legislation and its planned end-of-waste-criteria, the chemical legislation and the Construction Products Directive. The target audience of this report is companies producing ashes and having a use or seeing a use for its ash. The report describes how to make a REACH registration of ash independent if a company did or did not pre-register ash during 2008. It describes how to change from one ash registration into another if the pre-registration was done for one type of ash but the company changes opinion during the sameness check, i.e. changing SIEF (Appendix A). Taking part in REACH registration projects during 2009-2010 can be advantageous since knowledge and financing are shared. Ash can be REACH registered also in the future but it is important to know that the registration have to be done prior the production and marketing starts. If ash is consider to be a waste the handling is covered by the community and national waste legislation. In Sweden ashes are by and large being regarded as waste, and recycling is risk assessed and permits are given case by case. End-of-waste criteria for different waste material are being elaborated within the EU. Such criteria will among other details cover chemical safety. When a material fulfils the end-of-waste criteria such material

  8. Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers.

    Science.gov (United States)

    Arenas, Celia; Leiva, Carlos; Vilches, Luis F; Cifuentes, Héctor

    2013-11-01

    The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final co