Oxy-fuel combustion of millimeter-sized coal char: Particle temperatures and NO formation

DEFF Research Database (Denmark)

Brix, Jacob; Navascués, Leyre Gómez; Nielsen, Joachim Bachmann

2013-01-01

In this work, differences in particle temperature and NO yield during char oxidation in O2/N2 and O2/CO2 atmospheres, respectively, have been examined. A laboratory scale fixed bed reactor, operated isothermally at 1073 K, was used for combustion of millimeter-sized lignite and bituminous coal char...... increased with mass loading, by as much as 700 K above the furnace set point. The formation of NO from lignite char was not influenced by the change from N2 to CO2 whereas the NO yield from bituminous coal char was considerably lower in O2/CO2 compared O2/N2. For both chars the conversion to NO decreased...... as the O2 concentration or the particle size increased. However, for the bituminous coal char, a peak in NO yield was observed at an intermediate particle size of 0.1–0.2 g. The differences in the effect of gas atmosphere, O2 concentration, and particle mass on the NO yield from oxidation of bituminous...

Fundamental study of the pulverized coal char combustion in oxyfuel mode with drop tube furnace

Energy Technology Data Exchange (ETDEWEB)

Ito, Takamasa; Takafuji, Makoto; Suda, Toshiyuki; Fujimori, Toshiro [Heat and Fluid Dynamics Department, Yokohama (Japan)

2013-07-01

The combustion characteristics of coal char particles in either O{sub 2}/N{sub 2} or O{sub 2}/CO{sub 2} conditions were experimentally investigated. Especially, the char burnout, the char particle temperature and the shrinkage of the char particles were discussed. A Drop Tube Furnace (DTF: whose wall temperature was set at 873, 923 and 973 K) was used as the experimental apparatus. The experimental results revealed that, in equivalent oxygen concentration, the char burnout and the char particle temperature were higher in O{sub 2}/N{sub 2} conditions than those in O{sub 2}/CO{sub 2} conditions. The shrinkage of the char particle did not show the large difference in either O{sub 2}/N{sub 2} or O{sub 2}/CO{sub 2} conditions. Up to 15% of char burnout, the char particle diameters were reduced gradually. Up to 80% of char burnout, the char particle diameters were not changed. This is supposed that the chemical reaction is mainly occurred not on the external surface but on the internal surface of the char particle. Over 80% of char burnout, sudden shrinkage could be seen. Finally, an empirical equation for the prediction of the char particle shrinkage was introduced. Further investigation is required in high operating temperature, where CO{sub 2} gasification may have a large influence on the char burnout.

Investigation on the fast co-pyrolysis of sewage sludge with biomass and the combustion reactivity of residual char.

Science.gov (United States)

Deng, Shuanghui; Tan, Houzhang; Wang, Xuebin; Yang, Fuxin; Cao, Ruijie; Wang, Zhao; Ruan, Renhui

2017-09-01

Gaining the valuable fuels from sewage sludge is a promising method. In this work, the fast pyrolysis characteristics of sewage sludge (SS), wheat straw (WS) and their mixtures in different proportions were carried out in a drop-tube reactor. The combustion reactivity of the residual char obtained was investigated in a thermogravimetric analyzer (TGA). Results indicate that SS and WS at different pyrolysis temperatures yielded different characteristic gas compositions and product distributions. The co-pyrolysis of SS with WS showed that there existed a synergistic effect in terms of higher gas and bio-oil yields and lower char yield, especially at the WS adding percentage of 80wt%. The addition of WS to SS increased the carbon content in the SS char and improved char porous structures, resulting in an improvement in the combustion reactivity of the SS char. The research results can be used to promote co-utilization of sewage sludge and biomass. Copyright © 2017. Published by Elsevier Ltd.

Investigation on the ignition, thermal acceleration and characteristic temperatures of coal char combustion

International Nuclear Information System (INIS)

Zhang, Bin; Fu, Peifang; Liu, Yang; Yue, Fang; Chen, Jing; Zhou, Huaichun; Zheng, Chuguang

2017-01-01

Highlights: • A new thermal model and measuring method for the ignition temperature are proposed. • Ignition occurs in a region but not a point with ambient conditions changing. • Ignition region is measured from the minimum to maximum ignition temperature. • T_i_g_,_m_a_x of coal char in TG-DSC is in line with the ignition temperature of EFR. - Abstract: Through using a new thermal analysis model and a method of coal/char combustion, the minimum ignition temperature and minimum ignition heat of three different ranks of pulverized coal char were measured by simultaneous Thermogravimetry and Differential Scanning Calorimetry (TG-DSC) experiments. The results show that the ignition of coal char occurs in the range between the minimum ignition temperature and the inflection-point temperature. The thermal acceleration and its gradient G_T increase with increasing heating rate and decrease with increasing coal char rank. The higher the G_T of the coal char, the more easily the ignition occurs and more rapidly the burning and burnout occur. The data show that the G_T of coal char of SLH lignite is 1.6 times more than that of coal char of ZCY bituminous and JWY anthracite in ignition zone, and 3.4 times in burning zone. The characteristic temperatures increase with increasing temperature of prepared char, heating rate and char rank. Moreover, the T_i_g_,_m_a_x calculated in DSC experiment is approximately in line with the ignition temperature obtained in the entrained flow reactor, which demonstrates the feasibility of the proposed theory.

Particle behavior and char burnout mechanisms under pressurized combustion conditions

Energy Technology Data Exchange (ETDEWEB)

Bauer, C.M.; Spliethoff, H.; Hein, K.R.G.

1999-07-01

Combined cycle systems with coal-fired gas turbines promise highest cycle efficiencies for this fuel. Pressurized pulverized coal combustion, in particular, yields high cycle efficiencies due to the high flue gas temperatures possible. The main problem, however, is to ensure a flue gas clean enough to meet the high gas turbine standards with a dirty fuel like coal. On the one hand, a profound knowledge of the basic chemical and physical processes during fuel conversion under elevated pressures is required whereas on the other hand suitable hot gas cleaning systems need to be developed. The objective of this work was to provide experimental data to enable a detailed description of pressurized coal combustion processes. A series of experiments were performed with two German hvb coals, Ensdorf and Goettelborn, and one German brown coal, Garzweiler, using a semi-technical scale pressurized entrained flow reactor. The parameters varied in the experiments were pressure, gas temperature and bulk gas oxygen concentration. A two-color pyrometer was used for in-situ determination of particle surface temperatures and particle sizes. Flue gas composition was measured and solid residue samples taken and subsequently analyzed. The char burnout reaction rates were determinated varying the parameters pressure, gas temperature and initial oxygen concentration. Variation of residence time was achieved by taking the samples at different points along the reaction zone. The most influential parameters on char burnout reaction rates were found to be oxygen partial pressure and fuel volatile content. With increasing pressure the burn-out reactions are accelerated and are mostly controlled by product desorption and pore diffusion being the limiting processes. The char burnout process is enhanced by a higher fuel volatile content.

The kinetics of combustion of chars derived from sewage sludge

Energy Technology Data Exchange (ETDEWEB)

J.S. Dennis; R.J. Lambert; A.J. Milne; S.A. Scott; A.N. Hayhurst [University of Cambridge, Cambridge (United Kingdom). Department of Chemical Engineering

2005-02-01

Experiments have been conducted to determine the combustion characteristics of sewage sludge chars in electrically heated beds of silica sand fluidised by air. The effects of the initial size of the char particles, the temperature of the bed and the concentration of (O{sub 2}) in the fluidising gas were investigated. Also, the temperatures of burning particles were measured with embedded thermocouples. The kinetics of combustion were measured at temperatures low enough for the CO formed by initial reaction between the carbon and oxygen to burn at some distance away from the particle. It is probable that the lower value is closer to the actual value, thought to be 135{+-}15 kJ/mol, reflecting the catalytic nature of the ash skeleton on which the carbon is supported. It was possible to obtain good agreement between measured burnout times and those predicted using the grain model of Szekely J, Evans JW, Sohn HY. Gas-solid reactions. New York: Academic Press; 1976, for the case where the kinetics are controlled by a combination of: (i) external mass transfer of oxygen from the particulate phase to the external surface of the burning char particle, (ii) diffusion of oxygen from the external surface into the porous matrix to the surfaces of grains, of which the solid is composed, and (iii) diffusion of oxygen into the microporous grains, where reaction occurs with the carbon. It was found that, for particles with diameters of 2 mm or larger, the initial rates of reaction, for bed temperatures in excess of 750{degree}C, are dominated by external mass transfer. 22 refs., 8 figs., 1 tab.

Coal char combustion under a CO{sub 2}-rich atmosphere: Implications for pulverized coal injection in a blast furnace

Energy Technology Data Exchange (ETDEWEB)

Borrego, A.G.; Casal, M.D. [Instituto Nacional del Carbon, CSIC. P.O. Box 73, 33080 Oviedo (Spain); Osorio, E.; Vilela, A.C.F. [Laboratorio de Siderurgia, DEMET/PPGEM - Universidade Federal do Rio Grande do Sul. P.O. Box 15021, 91501-970 Porto Alegre (Brazil)

2008-11-15

Pulverized coal injection (PCI) is employed in blast furnace tuyeres attempting to maximize the injection rate without increasing the amount of unburned char inside the stack of the blast furnace. When coal is injected with air through the injection lance, the resolidified char will burn in an atmosphere with a progressively lower oxygen content and higher CO{sub 2} concentration. In this study an experimental approach was followed to separate the combustion process into two distinct devolatilization and combustion steps. Initially coal was injected into a drop tube furnace (DTF) operating at 1300 C in an atmosphere with a low oxygen concentration to ensure the combustion of volatiles and prevent the formation of soot. Then the char was refired into the DTF at the same temperature under two different atmospheres O{sub 2}/N{sub 2} (typical combustion) and O{sub 2}/CO{sub 2} (oxy-combustion) with the same oxygen concentration. Coal injection was also performed under a higher oxygen concentration in atmospheres typical for both combustion and oxy-combustion. The fuels tested comprised a petroleum coke and coals currently used for PCI injection ranging from high volatile to low volatile bituminous rank. Thermogravimetric analyses and microscopy techniques were used to establish the reactivity and appearance of the chars. Overall similar burnouts were achieved with N{sub 2} and CO{sub 2} for similar oxygen concentrations and therefore no loss in burnout should be expected as a result of enrichment in CO{sub 2} in the blast furnace gas. The advantage of increasing the amount of oxygen in a reacting atmosphere during burnout was found to be greater, the higher the rank of the coal. (author)

Combustion Characteristics Of Agricultural Waste-Coal Char Blends

International Nuclear Information System (INIS)

Akpabio, I. O; Danbature W

2002-01-01

Shortage of petroleum products, depletion of huge forest reserves for fuel purposes with its attendant erosion problems and other environmental considerations have necessitated investigations into other sources of fuel. In this wise. a set of seven types of briquettes were prepared from agricultural wastes such as rice husk, maize husk and saw-dust and blends of carbonized coal char. Strong and well-formed briquettes with good combustion characteristics were obtained. The results obtained from water boiling tests show that 2 litres of water could be boiled just under 23 minutes. Moisture contents and strengths of these briquettes were also determined and are discussed. The results show that wastes could be converted into useful fuel

Char crystalline transformations during coal combustion and their implications for carbon burnout

Energy Technology Data Exchange (ETDEWEB)

Hurt, R.H.

1999-03-11

Residual, or unburned carbon in fly ash affects many aspects of power plant performance and economy including boiler efficiency, electrostatic precipitator operation, and ash as a salable byproduct. There is a large concern in industry on the unburned carbon problem due to a variety of factors, including low-NOx combustion system and internationalization of the coal market. In recent work, it has been found that residual carbon extracted from fly ash is much less reactive than the laboratory chars on which the current kinetics are based. It has been suggested that thermal deactivation at the peak temperature in combustion is a likely phenomenon and that the structural ordering is one key mechanism. The general phenomenon of carbon thermal annealing is well known, but there is a critical need for more data on the temperature and time scale of interest to combustion. In addition, high resolution transmission electron microscopy (HRTEM) fringe imaging, which provides a wealth of information on the nature and degree of crystallinity in carbon materials such as coal chars, has become available. Motivated by these new developments, this University Coal Research project has been initiated with the following goals: to determine transient, high-temperature, thermal deactivation kinetics as a function of parent coal and temperature history; and to characterize the effect of this thermal treatment on carbon crystalline structure through high-resolution transmission electron microscopy and specialized, quantitative image analysis.

Char crystalline transformations during coal combustion and their implications for carbon burnout

Energy Technology Data Exchange (ETDEWEB)

Hurt, R.H.

1999-07-07

Residual, or unburned carbon in fly ash affects many aspects of power plant performance and economy including boiler efficiency, electrostatic precipitator operation, and ash as a salable byproduct. There is a large concern in industry on the unburned carbon problem due to a variety of factors, including low-NOx combustion system and internationalization of the coal market. In recent work, it has been found that residual carbon extracted from fly ash is much less reactive than the laboratory chars on which the current kinetics are based. It has been suggested that thermal deactivation at the peak temperature in combustion is a likely phenomenon and that the structural ordering is one key mechanism. The general phenomenon of carbon thermal annealing is well known, but there is a critical need for more data on the temperature and time scale of interest to combustion. In addition, high resolution transmission electron microscopy (HRTEM) fringe imaging, which provides a wealth of information on the nature and degree of crystallinity in carbon materials such as coal chars, has become available. Motivated by these new developments, this University Coal Research project has been initiated with the following goals: (1) To determine transient, high-temperature, thermal deactivation kinetics as a function of parent coal and temperature history. (2) To characterize the effect of the thermal treatment on carbon crystalline structure through high-resolution transmission electron microscopy and specialized, quantitative image analysis.

Modeling the Pyrolysis and Combustion Behaviors of Non-Charring and Intumescent-Protected Polymers Using “FiresCone”

Directory of Open Access Journals (Sweden)

Long Shi

2015-10-01

Full Text Available A mathematical model, named FiresCone, was developed to simulate the pyrolysis and combustion processes of different types of combustible materials, which also took into account both gas and solid phases. In the present study, some non-charring and intumescent-protected polymer samples were investigated regarding their combustion behaviors in response to pre-determined external heat fluxes. The modeling results were validated against the experimental outcomes obtained from a cone calorimeter. The predicted mass loss rates of the samples were found to fit reasonably well with the experimental data collected under various levels of external irradiation. Both the experimental and modeling results showed that the peak mass loss rate of the non-charring polymer material occurred near the end of burning, whereas for the intumescent-protected polymer it happed shortly after the start of the experiment. “FiresCone” is expected to act as a practical tool for the investigation of fire behavior of combustible materials. It is also expected to model fire scenarios under complicated conditions.

A preliminary high-pressure thermogravimetric study of combustion reactivity of a Collie coal char

Energy Technology Data Exchange (ETDEWEB)

Chan, Yii Leng; Zhang, Zhezi; Zhu, Mingming; Zhang, Dongke [Western Australia Univ., Crawley, WA (Australia). Centre for Energy (M473); Luan, Chao [Western Australia Univ., Crawley, WA (Australia). Centre for Energy (M473); Tsinghua Univ., Beijing (China). Inst. of Thermal Engineering; You, Changfu [Tsinghua Univ., Beijing (China). Inst. of Thermal Engineering

2013-07-01

The effect of pressure(up to 20 bar)on the reactivity of a char(150-160 {mu}m) produced from Western Australian Collie coal has been studied using a high-pressure thermogravimetric analyser (HP TGA). The pressure demonstrated a positive effect in enhancing char combustion reactivities.Kinetic parameters have been determined from the experimental data.The apparent reaction order was found to be approximately 0.7 and the apparent activation energies were 91.0 kJ/mol at atmospheric pressure and 1.5 kJ/mol at an elevated pressure(10 bar),indicating a shift in the control regimes of the reaction at elevated pressures.The lumped effect of the sample size, bulk diffusion,interparticle and intraparticle diffusion at the elevated pressures played an important role in reducing the mass transfer during the HP-TGA experimentation.Thus the activation energy calculated at elevated pressures may not represent the intrinsic activation energy of the char particles but the apparent values of the bulk of the samples.

Char characterisation and its application in a coal burnout mode

Energy Technology Data Exchange (ETDEWEB)

Michael Cloke; Tao Wu; Richelieu Barranco; Ed Lester [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering, Coal Technology Research Group

2003-10-01

In this study, char image analysis techniques have been employed to investigate the morphology of chars obtained from a Drop-Tube furnace. Char image analysis results have been incorporated as inputs to a char burnout model based on Hurt's CBK model. It has been observed that the char combustion rate was strongly affected by char structural parameters and the inclusion of char morphology has led to a better prediction of char burnout. It has also been suggested by the model that the inclusion of ash inhibition overestimates the resistance attributed by ash film and the consideration of ash film resistance should be undertaken in a different way to give a better prediction at the later stages of char combustion. 12 refs., 13 figs., 5 tabs.

Oxy-coal combustion in an entrained flow reactor: Application of specific char and volatile combustion and radiation models for oxy-firing conditions

DEFF Research Database (Denmark)

Álvarez, L.; Yin, Chungen; Riaza, J.

2013-01-01

The deployment of oxy-fuel combustion in utility boilers is one of the major options for CO2 capture. However, combustion under oxy-firing conditions differs from conventional air-firing combustion, e.g., in the aspect of radiative heat transfer, coal conversion and pollutants formation....... In this work, a numerical study on pulverised coal combustion was conducted to verify the applicability and accuracy of several sub-models refined for oxy-fuel conditions, e.g., gaseous radiative property model, gas-phase combustion mechanism and heterogeneous char reaction model. The sub-models were...... implemented in CFD (Computational Fluid Dynamics) simulations of combustion of three coals under air-firing and various oxy-firing (21-35% vol O2 in O2/CO2 mixture) conditions in an EFR (entrained flow reactor). The predicted coal burnouts and gaseous emissions were compared against experimental results...

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

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

Flat-flame burner studies of pulverized-coal combustion. Experimental results on char reactivity

Energy Technology Data Exchange (ETDEWEB)

Peck, R.E.; Shi, L.

1996-12-01

Structure of laminar, premixed pulverized-coal flames in a 1-D reactor has been studied with emphasis on char reactivity. A 1.1-meter-long tube furnace accommodated high-temperature environments and long residence times for the laminar flames produced by a flat-flame, coal-dust burner. Experiments were conducted at different operating conditions (fuel type/size, fuel-air ratio). Measurements included solid sample composition, major gas species and hydrocarbon species concentrations, and gas- and particle-phase line-of-sight temperatures at different axial locations in flames. Degree of char burnout increased with coal volatiles content and decreased with coal particle size. Combustion in furnace was in oxidizer-deficient environment and higher burnout was achieved as the fuel-air ratio neared stoichiometric. For 0-45 {mu}m particles most of the fixed carbon mass loss occurred within 5 cm of the furnace inlet, and char reaction was slow downstream due to low oxidizer concentrations. Fixed carbon consumption of the 45-90 {mu}m particles generally was slower than for the small particles. About 40%-80% of the fixed carbon was oxidized in the furnace. Primary volatiles mass loss occurred within the first 4.5 cm, and more than 90% of the volatiles were consumed in the flames. The flames stabilized in the furnace produced less CH{sub 4} and H{sub 2} in the burnt gas than similar unconfined flames. NO concentrations were found to decrease along the furnace and to increase with decreasing fuel/air ratio. Temperature measurement results showed that gas-phase temperatures were higher than solid-phase temperatures. Temperatures generally decreased with decreasing volatiles content and increased as the equivalence ratio approached one. The results can be used to interpret thermochemical processes occurring in pulverized-coal combustion. (au) 15 refs.

A burnout prediction model based around char morphology

Energy Technology Data Exchange (ETDEWEB)

T. Wu; E. Lester; M. Cloke [University of Nottingham, Nottingham (United Kingdom). Nottingham Energy and Fuel Centre

2005-07-01

Poor burnout in a coal-fired power plant has marked penalties in the form of reduced energy efficiency and elevated waste material that can not be utilized. The prediction of coal combustion behaviour in a furnace is of great significance in providing valuable information not only for process optimization but also for coal buyers in the international market. Coal combustion models have been developed that can make predictions about burnout behaviour and burnout potential. Most of these kinetic models require standard parameters such as volatile content, particle size and assumed char porosity in order to make a burnout prediction. This paper presents a new model called the Char Burnout Model (ChB) that also uses detailed information about char morphology in its prediction. The model can use data input from one of two sources. Both sources are derived from image analysis techniques. The first from individual analysis and characterization of real char types using an automated program. The second from predicted char types based on data collected during the automated image analysis of coal particles. Modelling results were compared with a different carbon burnout kinetic model and burnout data from re-firing the chars in a drop tube furnace operating at 1300{sup o}C, 5% oxygen across several residence times. An improved agreement between ChB model and DTF experimental data proved that the inclusion of char morphology in combustion models can improve model predictions. 27 refs., 4 figs., 4 tabs.

Coal pyrolysis and char burnout under conventional and oxy-fuel conditions

Energy Technology Data Exchange (ETDEWEB)

Al-Makhadmeh, L.; Maier, J.; Scheffknecht, G. [Stuttgart Univ. (Germany). Institut fuer Verfahrenstechnik und Dampfkesselwesen

2009-07-01

Coal utilization processes such as combustion or gasification generally involve several steps i.e., the devolatilization of organic materials, homogeneous reactions of volatile matter with the reactant gases, and heterogeneous reactions of the solid (char) with the reactant gases. Most of the reported work about coal pyrolysis and char burnout were performed at low temperatures under environmental conditions related to the air firing process with single particle tests. In this work, coal combustion under oxy-fuel conditions is investigated by studying coal pyrolysis and char combustion separately in practical scales, with the emphasis on improving the understanding of the effect of a CO{sub 2}-rich gas environment on coal pyrolysis and char burnout. Two coals, Klein Kopje a medium volatile bituminous coal and a low-rank coal, Lausitz coal were used. Coal pyrolysis in CO{sub 2} and N{sub 2} environments were performed for both coals at different temperatures in an entrained flow reactor. Overall mass release, pyrolysis gas concentrations, and char characterization were performed. For char characterization ultimate analysis, particle size, and BET surface area were measured. Chars for both coals were collected at 1150 C in both CO{sub 2} and N{sub 2} environments. Char combustion was performed in a once-through 20 kW test facility in O{sub 2}/CO{sub 2} and O{sub 2}/N{sub 2} atmospheres. Besides coal quality, oxygen partial pressure was chosen as a variable to study the effect of the gas environment on char burnout. In general, it is found that the CO{sub 2} environment and coal rank have a significant effect on coal pyrolysis and char burnout. (orig.)

Oxidation rates of carbon and nitrogen in char residues from solid fuels

Energy Technology Data Exchange (ETDEWEB)

Karlstroem, O.

2013-06-01

Computational fluid dynamics (CFD) modeling is an important tool in designing new combustion systems. By using CFD modeling, entire combustion systems can be modeled and the emissions and the performance can be predicted. CFD modeling can also be used to develop new and better combustion systems from an economical and environmental point of view. In CFD modeling of solid fuel combustion, the combustible fuel is generally treated as single fuel particles. One of the limitations with the CFD modeling concerns the sub-models describing the combustion of single fuel particles. Available models in the scientific literature are in many cases not suitable as submodels for CFD modeling since they depend on a large number of input parameters and are computationally heavy. In this thesis CFD-applicable models are developed for the combustion of single fuel particles. The single particle models can be used to improve the combustion performance in various combustion devices or develop completely new technologies. The investigated fields are oxidation of carbon (C) and nitrogen (N) in char residues from solid fuels. Modeled char-C oxidation rates are compared to experimental oxidation rates for a large number of pulverized solid fuel chars under relevant combustion conditions. The experiments have been performed in an isothermal plug flow reactor operating at 1123-1673 K and 3-15 vol.% O{sub 2}. In the single particle model, the char oxidation is based on apparent kinetics and depends on three fuel specific parameters: apparent pre-exponential factor, apparent activation energy, and apparent reaction order. The single particle model can be incorporated as a sub-model into a CFD code. The results show that the modeled char oxidation rates are in good agreement with experimental char oxidation rates up to around 70% of burnout. Moreover, the results show that the activation energy and the reaction order can be assumed to be constant for a large number of bituminous coal chars

A burnout prediction model based around char morphology

Energy Technology Data Exchange (ETDEWEB)

Tao Wu; Edward Lester; Michael Cloke [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering

2006-05-15

Several combustion models have been developed that can make predictions about coal burnout and burnout potential. Most of these kinetic models require standard parameters such as volatile content and particle size to make a burnout prediction. This article presents a new model called the char burnout (ChB) model, which also uses detailed information about char morphology in its prediction. The input data to the model is based on information derived from two different image analysis techniques. One technique generates characterization data from real char samples, and the other predicts char types based on characterization data from image analysis of coal particles. The pyrolyzed chars in this study were created in a drop tube furnace operating at 1300{sup o}C, 200 ms, and 1% oxygen. Modeling results were compared with a different carbon burnout kinetic model as well as the actual burnout data from refiring the same chars in a drop tube furnace operating at 1300{sup o}C, 5% oxygen, and residence times of 200, 400, and 600 ms. A good agreement between ChB model and experimental data indicates that the inclusion of char morphology in combustion models could well improve model predictions. 38 refs., 5 figs., 6 tabs.

Effective Diffusion Coefficients in Coal Chars

DEFF Research Database (Denmark)

Johnsson, Jan Erik; Jensen, Anker

2001-01-01

Knowledge of effective diffusion coefficients in char particles is important when interpreting experimental reactivity measurements and modeling char combustion or NO and N2O reduction. In this work, NO and N2O reaction with a bituminous coal char was studied in a fixed-bed quartz glass reactor....... In the case of strong pore diffusion limitations, the error in the interpretation of experimental results using the mean pore radius could be a factor of 5 on the intrinsic rate constant. For an average coal char reacting with oxygen at 1300 K, this would be the case for particle sizes larger than about 50...

Sulfate reduction and carbon removal during kraft char burning

Energy Technology Data Exchange (ETDEWEB)

Waag, K.J.; Frederick, W.J.; Sricharoenchaikul, V [Oregon State Univ., Corvallis, OR (United States). Dept. of Chemical Engineering; Grace, T.M. [T.M. Grace Company, Appleton, WI (United States); Kymalainen, M. [Tampella Power, Tampere (Finland)

1995-12-31

An improved mathematical model of char burning during black liquor combustion was described. Enhancements include a proper treatment of CO{sub 2} and H{sub 2}O gasification, reactions between oxygen and combustibles in the boundary layer, and integration of sulfate reduction and sulfide reoxidation into the char burning process. Gasification of char carbon by reaction with H{sub 2}O and CO{sub 2} proved to be the most important means of carbon release under typical recovery furnace conditions. Sulfate reduction was shown to be responsible for only a minor part of the carbon release. Simulations showed that for typical recovery boiler conditions, char burning behavior is independent of oxygen concentration up to the point of carbon depletion. After carbon depletion, sulfide reoxidation occurs at a rate determined by oxygen mass transfer. Process variables that had the biggest effect on char burning behavior were initial black liquor drop diameter and temperature; also there was a direct link between char burnout times and the amount of sulfate reduction. At a given temperature, any variable that shortened the char burnout time resulted in proportionately less reduction. 22 refs., 10 figs., 2 tabs.

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)

Modeling char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

DEFF Research Database (Denmark)

Brix, Jacob; Jensen, Peter Arendt; Jensen, Anker Degn

2011-01-01

The aim of this investigation has been to model combustion under suspension fired conditions in O2/N2 and O2/CO2 mixtures. Experiments used for model validation have been carried out in an electrically heated Entrained Flow Reactor (EFR) at temperatures between 1173 K and 1673 K with inlet O2...... concentrations between 5 and 28 vol.%. The COal COmbustion MOdel, COCOMO, includes the three char morphologies: cenospheric char, network char and dense char each divided between six discrete particle sizes. Both combustion and gasification with CO2 are accounted for and reaction rates include thermal char...

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.

IEA combustion agreement : a collaborative task on alternative fuels in combustion

International Nuclear Information System (INIS)

Larmi, M.

2009-01-01

The focus of the alternative fuels in combustion task of the International Energy Agency is on high efficiency engine combustion, furnace combustion, and combustion chemistry. The objectives of the task are to develop optimum combustion for dedicated fuels by fully utilizing the physical and chemical properties of synthetic and renewable fuels; a significant reduction in carbon dioxide, NOx and particulate matter emissions; determine the minimum emission levels for dedicated fuels; and meet future emission standards of engines without or with minimum after-treatment. This presentation discussed the alternative fuels task and addressed issues such as synthetic fuel properties and benefits. The anticipated future roadmap was presented along with a list of the synthetic and renewable engine fuels to be studied, such as neat oxygenates like alcohols and ethers, biogas/methane and gas combustion, fuel blends, dual fuel combustion, high cetane number diesel fuels like synthetic Fischer-Tropsch diesel fuel and hydrogenated vegetable oil, and low CN number fuels. Implementation examples were also discussed, such as fuel spray studies in optical spray bombs; combustion research in optical engines and combustion chambers; studies on reaction kinetics of combustion and emission formation; studies on fuel properties and ignition behaviour; combustion studies on research engines; combustion optimization; implementing the optimum combustion in research engines; and emission measurements. Overall milestone examples and the overall schedule of participating countries were also presented. figs.

Properties and Developments of Combustion and Gasification of Coal and Char in a CO2-Rich and Recycled Flue Gases Atmosphere by Rapid Heating

Directory of Open Access Journals (Sweden)

Zhigang Li

2012-01-01

Full Text Available Combustion and gasification properties of pulverized coal and char have been investigated experimentally under the conditions of high temperature gradient of order 200°C·s−1 by a CO2 gas laser beam and CO2-rich atmospheres with 5% and 10% O2. The laser heating makes a more ideal experimental condition compared with previous studies with a TG-DTA, because it is able to minimize effects of coal oxidation and combustion by rapid heating process like radiative heat transfer condition. The experimental results indicated that coal weight reduction ratio to gases followed the Arrhenius equation with increasing coal temperature; further which were increased around 5% with adding H2O in CO2-rich atmosphere. In addition, coal-water mixtures with different water/coal mass ratio were used in order to investigate roles of water vapor in the process of coal gasification and combustion. Furthermore, char-water mixtures with different water/char mass ratio were also measured in order to discuss the generation ratio of CO/CO2, and specified that the source of Hydrocarbons is volatile matter from coal. Moreover, it was confirmed that generations of CO and Hydrocarbons gases are mainly dependent on coal temperature and O2 concentration, and they are stimulated at temperature over 1000°C in the CO2-rich atmosphere.

Particle-based characterisation of pulverised coals and chars for carbon burnout studies

Energy Technology Data Exchange (ETDEWEB)

Gibbins, J.R.; Seitz, M.H.; Kennedy, S.M.; Beeley, T.J.; Riley, G.S. [Imperial College of Science, Technology and Medicine, London (United Kingdom). Mechanical Engineering Department

1999-07-01

The study of individual particle properties, as opposed to averaged behaviour of differing particles, was carried out for the combustion of coals and chars using optical microscopy and digital image processing. Chars from entrained flow reactors and corresponding pulverized fuel samples were characterized to examine possible char particle origins for real heterogeneous particles. 7 refs., 5 figs., 1 tab.

NO Reduction over Biomass and Coal Char during Simultaneous Combustion

DEFF Research Database (Denmark)

Zhao, Ke; Glarborg, Peter; Jensen, Anker Degn

2013-01-01

This paper reports an experimental study of NO reduction over chars of straw, bark, bituminous coal, and lignite. The experiments were performed in a fixed bed reactor in the temperature range 850–1150 °C. The chars were generated by in situ pyrolysis at the reaction temperature to minimize further...

Combustion studies in a fluidised bed-The link between temperature, NO{sub x} and N{sub 2}O formation, char morphology and coal type

Energy Technology Data Exchange (ETDEWEB)

Valentim, B.; Lemos de Sousa, M.J. [Centro de Geologia da Universidade do Porto, Faculdade de Ciencias, Praca de Gomes Teixeira, 4099-002, Porto (Portugal); Abelha, P.; Boavida, D.; Gulyurtlu, I. [Departamento de Engenharia Energetica e Controlo Ambiental (DEECA), Instituto Nacional de Engenharia, Tecnologia e Inovacao (INETI), Estrada do Paco do Lumiar, 22, Edif. J, 1649-038, Lisboa (Portugal)

2006-06-06

Five commercially available high volatile bituminous coals from different origins were studied with the objective of characterizing their petrographic nature with respect to emissions of NO{sub x} and N{sub 2}O. The chars produced [at temperatures ranging from 700 to 1000 {sup o}C] from these coals were also petrographic ally analyzed to assess the contribution of char to NO{sub x} and N{sub 2}O formation during combustion. Vitrinite-rich coals produced higher porous chars (cenospheres and tenuinetworks) than those that are rich in inertinite. The former coals were, however, found to release lower concentrations of NO. Consistent with previous works, N{sub 2}O emissions were observed to decrease significantly with temperature, however, on the whole, the N{sub 2}O emissions from vitrinite-rich high volatile coals were less than those from inertinite-rich coals. Additionally, high porous chars were found to give rise to lower emissions of NO and N{sub 2}O. (author)

Influence of Torrefaction on Single Particle Combustion of Wood

DEFF Research Database (Denmark)

Lu, Zhimin; Jian, Jie; Jensen, Peter Arendt

2016-01-01

This study focuses on the influence of torrefaction on the char reactivity, char yield, and combustion time of 3-5 mm spherical wood particles in a single particle combustion reactor (SPC) operating at a nominal temperature of 1231 °C. The devolatilization times were reduced and the char burnout...

Char characterization and DTF assays as tools to predict burnout of coal blends in power plants

Energy Technology Data Exchange (ETDEWEB)

C. Ulloa; A.G. Borrego; S. Helle; A.L. Gordon; X. Garcia [Universidad de Concepcion, Concepcion (Chile). Departamento de Ingenieria Quimica

2005-02-01

The aim of this study is to predict efficiency deviations in the combustion of coal blends in power plants. Combustion of blends, as compared to its single coals, shows that for some blends the behavior is non-additive in nature. Samples of coal feed and fly ashes from combustion of blends at two power plants, plus chars of the parent coals generated in a drop-tube furnace (DTF) at temperatures and heating rates similar to those found in the industrial boilers were used. Intrinsic kinetic parameters, burning profiles and petrographic characteristics of these chars correlated well with the burnout in power plants and DTF experiments. The blend combustion in a DTF reproduces both positive and negative burnout deviations from the expected weighted average. These burnout deviations have been previously attributed to parallel or parallel-series pathways of competition for oxygen. No deviations were found for blends of low rank coals of similar characteristics yielding chars close in morphology, optical texture and reactivity. Negative deviations were found for blends of coals differing moderately in rank and were interpreted as associated with long periods of competition. In this case, fly-ashes were enriched in material derived from the least reactive char, but also unburnt material attributed to the most reactive char was identified. Improved burnout compared to the weighted average was observed for blends of coals very different in rank, and interpreted as the result of a short interaction period, followed by a period where the less reactive char burns under conditions that are more favorable to its combustion. In this case, only unburned material from the least reactive char was identified in the fly-ashes. 20 refs., 9 figs., 5 tabs.

Active sites in char gasification: Final technical report

Energy Technology Data Exchange (ETDEWEB)

Wojtowicz, M.; Lilly, W.D.; Perkins, M.T.; Hradil, G.; Calo, J.M.; Suuberg, E.M.

1987-09-01

Among the key variables in the design of gasifiers and combustors is the reactivity of the chars which must be gasified or combusted. Significant loss of unburned char is unacceptable in virtually any process; the provision of sufficient residence time for complete conversion is essential. A very wide range of reactivities are observed, depending upon the nature of the char in a process. The current work focuses on furthering the understanding of gasification reactivities of chars. It has been well established that the reactivity of char to gasification generally depends upon three principal factors: (1) the concentration of ''active sites'' in the char; (2) mass transfer within the char; and (3) the type and concentration of catalytic impurities in the char. The present study primarily addresses the first factor. The subject of this research is the origin, nature, and fate of active sites in chars derived from parent hydrocarbons with coal-like structure. The nature and number of the active sites and their reactivity towards oxygen are examined in ''model'' chars derived from phenol-formaldehyde type resins. How the active sites are lost by the process of thermal annealing during heat treatment of chars are studied, and actual rate for the annealing process is derived. Since intrinsic char reactivities are of primary interest in the present study, a fair amount of attention was given to the model char synthesis and handling so that the effect of catalytic impurities and oxygen-containing functional groups in the chemical structure of the material were minimized, if not completely eliminated. The project would not be considered complete without comparing characteristic features of synthetic chars with kinetic behavior exhibited by natural chars, including coal chars.

Joint project final report, Task II: Sulfur chemistry, Task III: Nitrogen Chemistry[Straw fired power plants

Energy Technology Data Exchange (ETDEWEB)

Glarborg, P.; Lans, R. van der; Weigang, L.; Arendt Jensen, P.; Degn Jensen, A.; Dam-Johansen, K.

2001-09-01

It is the aim of the project to promote the use of biomass in the production of power and heat in Denmark as well as enhancing the technology base of the Danish industry within this area. The project involves, the following task areas: 1) Deposit Build-up; 2) Sulfur Chemistry; 3) Nitrogen Chemistry; and 4) Furnace Modeling. The present report covers the activities in task 2 and 3, which are carried out at Department of Chemical Engineering, DTU. Task 2: Sulfur chemistry: The lab-scale results show that the amount of sulfur released into the gas-phase increases at high temperatures. Other process parameters such as oxygen concentration have less impact. Little sulfur is apparently released during char oxidation. The experiments show that about 40% of the sulfur is released during pyrolysis at 400 {sup d}eg{sup .}C. At combustion conditions it was found that about 50% of the sulfur is released at 500{sup d}eg.{sup C}; above this temperature an almost linear correlation is found beteen sulfur release and combustion temperature up to 80-85% release at 950{sup d}eg.{sup C}. The experiments are in agreement with results from full scale straw fired grate boilers, indicating that only a small amount of fuel-sulfur is fixed in the bottom ash under typical operating conditions. The results are important in order to understand the varying emission levels observed in full-scala systems and provide guidelines for low SO{sub 2} operation. Task 3: Nitrogen chemistry: In the nitgrogen chemistry submodel volatile-N is released as NH{sub 3} and N{sub 2}. The ammonia can react further to N{sub 2} or NO. Char nitrogen is oxidized to NO, and the char bed acts as a catalyst for the reduction of NO to N{sub 2}. Predictions with the bed-model including the NO submodel indicate that when all volatile nitrogen is converted to NH{sub 3}, the concentrations og NH{sub 3} are significantly overpredicted. This means that either the NH{sub 3} reaction rates are underpredicted or that a smaller

The ChemChar process

International Nuclear Information System (INIS)

Manahan, S.E.; Kinner, L.L.; Larsen, D.W.

1992-01-01

This paper reports on reverse-burn gasification is a thermochemical process that offers a number of advantages over conventional incineration for the treatment of a variety of waste materials. Patented as the ChemChar Process, reverse-burn gasification can treat wastes in the forms of solids, liquids, sludges, and soils. Waste constituents are destroyed by conversion to a combustible gas and to a dry, inert, carbonaceous solid which is either non-hazardous or can be readily mixed with cement to prevent leaching of the radioactive, toxic, or heavy metal constituents that are retained in the char residue or ash. In this way, reverse-burn gasification can be a very effective method for treating organic waste sludges containing heavy metals and mixed wastes consisting of hazardous chemicals contaminated with radioactive substances. As with any gasification waste treatment process, reverse-burn gasification offers inherent advantages in the areas of destruction efficiency and emissions control. This is because, instead of an exhaust gas that must treated to control emissions, gasification produces a combustible gas that is burned. Trace levels of contaminants are destroyed in burning the gas, and a catalyst may be employed, if necessary

Suspension Combustion of Wood: Influence of Pyrolysis Conditions on Char Yield, Morphology, and Reactivity

DEFF Research Database (Denmark)

Dall'Ora, Michelangelo; Jensen, Peter Arendt; Jensen, Anker Degn

2008-01-01

Chars from pine and beech wood were produced by fast pyrolysis in an entrained flow reactor and by slow pyrolysis in a thermogravimetric analyzer. The influence of pyrolysis temperature, heating rate and particle size on char yield and morphology was investigated. The applied pyrolysis temperature...... varied in the range 673−1673 K for slow pyrolysis and between 873 and 1573 K for fast pyrolysis. The chars were oxidized in a thermogravimetric analyzer and the mass loss data were used to determine char oxidation reactivity. Char yield from fast pyrolysis (104−105 K/s) was as low as 1 to 6% on a dry ash......, char oxidation reactivity decreased as pyrolysis temperature increased. The amount and composition of the ash forming matter of the wood fuels seems to play an important role in determining the differences in char yield, morphology and reactivity....

Combustion-derived substances in deep basins of Puget Sound: Historical inputs from fossil fuel and biomass combustion

International Nuclear Information System (INIS)

Kuo, Li-Jung; Louchouarn, Patrick; Herbert, Bruce E.; Brandenberger, Jill M.; Wade, Terry L.; Crecelius, Eric

2011-01-01

Reconstructions of 250 years historical inputs of two distinct types of black carbon (soot/graphitic black carbon (GBC) and char-BC) were conducted on sediment cores from two basins of the Puget Sound, WA. Signatures of polycyclic aromatic hydrocarbons (PAHs) were also used to support the historical reconstructions of BC to this system. Down-core maxima in GBC and combustion-derived PAHs occurred in the 1940s in the cores from the Puget Sound Main Basin, whereas in Hood Canal such peak was observed in the 1970s, showing basin-specific differences in inputs of combustion byproducts. This system showed relatively higher inputs from softwood combustion than the northeastern U.S. The historical variations in char-BC concentrations were consistent with shifts in climate indices, suggesting an influence of climate oscillations on wildfire events. Environmental loading of combustion byproducts thus appears as a complex function of urbanization, fuel usage, combustion technology, environmental policies, and climate conditions. - Research highlights: → We reconstructed the historical inputs of GBC and char-BC in Puget Sound, WA, USA. → Temporal trend of GBC was linked to human activities (urbanization, fuel usage). → Temporal trend of char-BC was more likely driven by regional climate oscillations. → Historical trends of combustion byproducts show the geographical heterogeneities. - Temporal trend of GBC was directly linked to human activities, while the input of char-BC in Puget Sound was more likely driven by regional climate oscillations.

Influence of char structure on reactivity and nitric oxide emissions

Energy Technology Data Exchange (ETDEWEB)

Arenillas, Ana; Rubiera, Fernando; Parra, Jose B.; Pis, Jose J. [Department of Energy and Environment, Instituto Nacional del Carbon, CSIC, Apartado 73, 33080 Oviedo (Spain)

2002-06-20

The aim of this study was to investigate the influence of coal rank and operating conditions during coal pyrolysis on the resultant char texture properties, morphology and reactivity. A range of bituminous coals were pyrolysed in a fixed bed reactor at different heating rates. It was found that the higher the heating rate and the lower the coal rank, the more microporous chars were obtained. Isothermal (500 C) gasification in 20% oxygen in argon of the chars was carried out using a differential thermogravimetric system (DTG). The results of this work indicated that the increase in the availability of char-active surface sites led to an increase in char reactivity, not only for oxygen but also for other reactive gases, in particular NO, diminishing emissions during the combustion process.

Corrosive components of nutshells and their chars

Directory of Open Access Journals (Sweden)

Karczewski Mateusz

2016-01-01

Full Text Available Biomass combustion stands among various technologies pointed at fossil fuels consumption decrease. Biomass can be found in very diversified sources spread more evenly across the globe, can be burned with use of traditional combustion solutions and is more CO2 neutral in combustion than their fossil fuel counterparts. On the other hand biomass has several problems with composition that despite its potential diversity. Problem of excess moisture can be already solved by material selection or by preliminary pyrolysis. The main problem concerns however biomass ash composition. Biomass ashes are more prone to have higher quantities of potentially corrosive components than their coal counterparts. The example of such constituents are alkali metals, sulphur and chlorine. Ash basic composition is also important due to various ash properties like its melting temperature and slagging or fouling tendencies. To address the problem, several indices for fast properties prediction and earlier problem identification can be appointed. This work concentrates on ash quality evaluation for potentially attractive biomass fuel from nutshell materials and their corresponding char obtained by pyrolysis in 300, 450 and 550 °C. Pistachio and hazelnut shells with their chars will be analysed for corrosive compounds and their potential influence on combustion process.

The effect of the textural properties of bituminous coal chars on NO emissions

Energy Technology Data Exchange (ETDEWEB)

Arenillas, A.; Rubiera, F.; Pis, J.J.; Jones, J.M.; Williams, A. [CSIC, Oviedo (Spain). Inst. Nacional del Carbon

1999-11-01

NO is the primary product of the oxidation of char nitrogen, and in some combustion processes the NO can be reduced on the char surface to give N{sub 2}O and/or N{sub 2}. In this study a range of bituminous coal (low, medium and high volatile matter content) were pyrolysed in a fixed bed reactor at various heating rates. Textural characterisation was carried out by measuring true (He) and apparent (Hg) densities and N{sub 2} (-196{degree}C) and CO{sub 2} (0{degree}C) adsorption isotherms. Pore volume distributions and surface areas were obtained for the chars studied. A thermogravimetric analyser coupled to a quadrupole mass spectrometer (TG-MS) was used to study the combustion behaviour of the samples and the nitrogen compounds evolved during temperature-programmed combustion. Results are discussed in terms of the influence of both textural properties and reactivity on NO emissions and on the heterogeneous reduction of NO. 23 refs., 8 figs., 4 tabs.

Investigation on the transient enthalpy of coal combustion

Energy Technology Data Exchange (ETDEWEB)

Fu, Pei-fang; Wang, Na; Yu, Bo; Zhang, Bin; Liu, Yang; Zhou, Huai-chun [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion

2013-07-01

The transient enthalpy ({Delta}h) of coal/char combustion of the three different coals (including anthracite, bituminous, and lignite) during the process of combustion is determined as a function of burn-off degree by using thermo-gravimetric-differential scanning calorimeter (TG-DSC) simultaneous thermal analyzer, and The error of determining calorific values of coals/chars is less 5% compared the results of TG-DSC with that of an automatic isoperibol calorimeter. It is found that In the initial stage, all the {Delta}h of coals are greater than that of the char pyrolysized from parent coal for many of volatiles contained more a great deal of heat per unit mass oxidized at low temperature, it also imply that coal is more easily ignited than char corresponded; And in the middle stage, all the {Delta}h of coals is lower than that of the char pyrolysized, so the pyrolysized char oxidation can supply much more of thermo-energy per unit mass. {Delta}h are almost a constant when the burn-off degree is equal to between 0.35/0.15 and 0.95/0.85 for ZCY bituminous coal/char and JWY anthracite/char, between 0.35/0.35 and 0.75/0.9 for SLH lignite/char; In the later stage, the {Delta}h of the coal/char decreased with the burn-off degree, it imply that the activity of the coal/char decreases. Therefore, coal pyrolysis changes not only the structure of char, but also the property of release heat; the transient enthalpy of coal/char combustion has been in change with the burn-out degree.

Relation between the petrographic composition of coal and the morphology of pyrolysis char produced in fluidized bed

Energy Technology Data Exchange (ETDEWEB)

B. Valentim; M.J. Lemos de Sousa; P. Abelha; D. Boavida; I. Gulyurtlu [Centro de Geologia da Universidade do Porto, Porto (Portugal)

2004-06-01

Several previous studies have already established, for pulverized coal combustion conditions, global correlations between petrographic composition of the coal and those of char produced from the same coal. However, for fluidized bed combustion, there has not been much new work since the eighties. The results presented in this paper include the petrographic characterization of seven different coals from several origins and also of their respective chars produced at 700, 800, 900, and 1000{sup o}C in a laboratory fluidized bed reactor. The results show a marked predominance of tenuispheres as the trial temperatures increase. While vitrinite-rich coals essentially produced highly porous chars, the inertinite-rich coals produced large amounts of medium- and low-porous chars. Semi-anthracite vitrinite produced high-porous chars and thermal affected coal particles originated low-porous and angular char morphotypes. The analysis of the data obtained revealed that vitrinite + liptinite related well with the high-porous char (sum of cenospheres and tenuinetworks), classified as Group 1. The same trend, but with a weaker relation, was also observed between vitrinite and liptinite rich microlithotypes and Group 1. 32 refs., 17 refs., 3 tabs.

Intrinsic reaction kinetics of coal char combustion by direct measurement of ignition temperature

International Nuclear Information System (INIS)

Kim, Ryang-Gyoon; Jeon, Chung-Hwan

2014-01-01

A wire heating reactor that can use a synchronized experimental method was developed to obtain the intrinsic kinetics of large coal char particles ranging in size from 0.4 to 1 mm. This synchronization system consists of three parts: a thermocouple wire for both heating and direct measurement of the particle temperature, a photodetector sensor for determining ignition/burnout points by measuring the intensity of luminous emission from burning particles, and a high-speed camera–long-distance microscope for observing and recording the movement of luminous zone directly. Coal char ignition was found to begin at a spot on the particle's external surface and then moved across the entire particle. Moreover, the ignition point determined according to the minimum of dT/dt is a spot point and not a full growth point. The ignition temperature of the spot point rises as the particle diameter increases. A spot ignition model, which describes the ignition in terms of the internal conduction and external/internal oxygen diffusion, was then developed to evaluate the intrinsic kinetics and predict the ignition temperature of the coal char. Internal conduction was found to be important in large coal char particles because its effect becomes greater than that of oxygen diffusion as the particle diameter increases. In addition, the intrinsic kinetics of coal char obtained from the spot ignition model for two types of coal does not differ significantly from the results of previous investigators. -- Highlights: • A novel technique was used to measure the coal char particle temperature. • The ignition point determined from a dT/dt minimum is a spot ignition point. • A spot ignition model was suggested to analyze the intrinsic reaction kinetics of coal char. • Internal conduction has to be considered in order to evaluate the intrinsic kinetics for larger particle (above 1 mm)

Development of an advanced continuous mild gasification process for the production of coproducts. Task 4, System integration studies: Char upgrading

Energy Technology Data Exchange (ETDEWEB)

Jha, M.C.; McCormick, R.L.; Hogsett, R.F.; Rowe, R.M.; Anast, K.R.

1991-12-01

This document describes the results of Task 4 under which a 50 pound/hour char-to-carbon (CTC) process research unit (PRU) was designed in the second half of 1989, with construction completed in June 1990. The CTC PRU at Golden was operated for nearly one year during which 35 runs were completed for a total of nearly 800 hours of operation. Char methanation and carbon production reactor development activities are detailed in this report, as well as the results of integrated runs of the CTC process. Evaluation of the process and the carbon product produced is also included. It was concluded that carbon could be produced from mild gasification char utilizing the CTC process. Char methanation and membrane separation steps performed reasonably well and can scaled up with confidence. However, the novel directly heated reactor system for methane cracking did not work satisfactorily due to materials of construction and heat transfer problems, which adversely affected the quantity and quality of the carbon product. Alternative reactor designs are recommended.

Phosphorus recovery from sewage sludge char ash

NARCIS (Netherlands)

Atienza-Martinez, M.; Gea, G.; Arauzo, J.; Kersten, Sascha R.A.; Kootstra, A.M.J.

2014-01-01

Phosphorus was recovered from the ash obtained after combustion at different temperatures (600 °C, 750 °C and 900 °C) and after gasification (at 820 °C using a mixture of air and steam as fluidising agent) of char from sewage sludge fast pyrolysis carried out at 530 °C. Depending on the leaching

New black liquor combustion characteristics III; Mustalipeaen uudet poltto-ominaisuudet III

Energy Technology Data Exchange (ETDEWEB)

Hupa, M.; Forssen, M.; Backman, R.; Enestam, S.; Lauren, T.; Skrifvars, B.J. [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

1997-10-01

The main purposes in this work is to: 1. Compare black liquor combustion characterization results to recovery boiler experiences. 2. Study the mechanisms of sodium release in black liquor combustion In the first part results from black liquor combustion characterization tests developed by Aabo Akademi University will be compared to experiences at four Finnish kraft recovery boilers. When comparing the laboratory data to the compiled field data emphasis will be put on the behavior of the black liquor during burning, the release of sodium and potassium, the melting behavior of the deposits and the NO and SO{sub 2} emissions. The main purpose in the second part of the work is to study the release mechanisms of sodium from black liquor char during combustion. Sodium is mainly released from the char by the mechanism where the molten sodiumcarbonate reacts with the char carbon. The study is divided into four subtasks and is performed mainly by conducting experiments in laboratory scale devices: (1) Sodium release during char reactions is studied for different liquors by analyzing the amount of sodium remaining in char after different holding times in a hot inert atmosphere. (2) A DTA/TGA apparatus is used to study in isothermal conditions the char reactions on prepyrolyzed char. (3) The effect of the form of sodium on the sodium release during char reactions. Black liquors added with different sodium salts (Na{sub 2}CO{sub 3}, Na{sub 2}SO{sub 4}, Na{sub 2}S{sub 2}O{sub 2}, Na{sub 2}S sekae NaCl) are used in experiments as in subtask 1. (4) Sodium release during combustion (2-5 % O{sub 2}) of single black liquor particles

Novel approaches in advanced combustion characterization of fuels for advanced pressurized combustion

Energy Technology Data Exchange (ETDEWEB)

Aho, M.; Haemaelaeinen, J. [VTT Energy (Finland); Joutsenoja, T. [Tampere Univ. of Technology (Finland)

1996-12-01

This project is a part of the EU Joule 2 (extension) programme. The objective of the research of Technical Research Centre of Finland (VTT) is to produce experimental results of the effects of pressure and other important parameters on the combustion of pulverized coals and their char derivates. The results can be utilized in modelling of pressurized combustion and in planning pilot-scale reactors. The coals to be studied are Polish hvb coal, French lignite (Gardanne), German anthracite (Niederberg) and German (Goettelbom) hvb coal. The samples are combusted in an electrically heated, pressurized entrained flow reactor (PEFR), where the experimental conditions are controlled with a high precision. The particle size of the fuel can vary between 100 and 300 {mu}m. The studied things are combustion rates, temperatures and sizes of burning single coal and char particles. The latter measurements are performed with a method developed by Tampere University of Technology, Finland. In some of the experiments, mass loss and elemental composition of the char residue are studied in more details as the function of time to find out the combustion mechanism. Combustion rate of pulverized (140-180 {mu}m) Gardanne lignite and Niederberg anthracite were measured and compared with the data obtained earlier with Polish hvb coal at various pressures, gas temperatures, oxygen partial pressures and partial pressures of carbon dioxide in the second working period. In addition, particle temperatures were measured with anthracite. The experimental results were treated with multivariable partial least squares (PLS) method to find regression equation between the measured things and the experimental variables. (author)

Heterogeneous reduction of nitric oxide on synthetic coal chars

Energy Technology Data Exchange (ETDEWEB)

C. Pevida; A. Arenillas; F. Rubiera; J.J. Pis [Instituto Nacional del Carbon (CSIC), Oviedo (Spain)

2005-12-01

Model compounds, with a controlled heteroatoms content and well-defined functionalities, were used to study the release of nitrogen compounds from char combustion. In the present work, the mechanisms involved in NO-char heterogeneous reduction were studied with a synthetic coal (SC) char as carbon source. Another synthetic char (SN) without any nitrogen in its composition was also employed in these studies. Temperature programmed reduction (TPR) tests with a gas mixture of 400 ppm NO in argon and with isotopically labelled nitric oxide, {sup 15}NO (500 ppm {sup 15}NO in argon), were carried out. The gases produced were quantitatively determined by means of MS and FTIR analysers. Under the conditions of this work the main products of the NO-C reaction were found to be N{sub 2} and CO{sub 2}. The main path of reaction involves the formation of surface nitrogen compounds that afterwards react with nitrogen from the reactive gas to form N{sub 2}. It was observed that fuel-N also participates in the overall heterogeneous reduction reaction, although to a lesser extent.

Investigating co-combustion characteristics of bamboo and wood.

Science.gov (United States)

Liang, Fang; Wang, Ruijuan; Jiang, Changle; Yang, Xiaomeng; Zhang, Tao; Hu, Wanhe; Mi, Bingbing; Liu, Zhijia

2017-11-01

To investigate co-combustion characteristics of bamboo and wood, moso bamboo and masson pine were torrefied and mixed with different blend ratios. The combustion process was examined by thermogravimetric analyzer (TGA). The results showed the combustion process of samples included volatile emission and oxidation combustion as well as char combustion. The main mass loss of biomass blends occurred at volatile emission and oxidation combustion stage, while that of torrefied biomass occurred at char combustion stage. With the increase of bamboo content, characteristic temperatures decreased. Compared with untreated biomass, torrefied biomass had a higher initial and burnout temperature. With the increase of heating rates, combustion process of samples shifted to higher temperatures. Compared with non-isothermal models, activation energy obtained from isothermal model was lower. The result is helpful to promote development of co-combustion of bamboo and masson pine wastes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of chars form biomass-derived materials: pectin chars

Energy Technology Data Exchange (ETDEWEB)

Sharma, R.K.; Wooten, J.B.; Baliga, V.L.; Hajaligol, M.R. [Philip Morris USA, Richmond, VA (United States). Research Center

2001-10-09

The effect of pyrolysis conditions on the yield and composition of char from pectin was studied. The volatile product was analyzed by gas chromatography/mass spectrometry (GC/MS). The solid product, i.e. char, was characterised by solid-state {sup 13}C nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectrsocopy. The char was also analysed for its elemental composition and surface area. The surface morphology of the char was studied by scanning electron microscopy (SEM). The results were compared to those from chlorogenic acid (CA). For both pectin and CA, the char yield decreased with increasing temperature before levelling-off at ca.20% of the starting substrate in non-oxidative runs. In oxidative runs, the char yields from both substrates became negligible at 550{degree}C. NMR analysis indicated that the aromatic character of char increased as the pyrolysis temperature increased. The oxygen functionality was progressively lost and the resonance bands corresponding to carbonyl groups mostly disappeared above 350{degree}C. FTIR analysis also suggested the loss of hydroxyl and carbonyl groups from chars at high temperatures. The H/C and O/C ratios of chars decreased continuously with increasing temperature. The oxidative chars showed characteristics essentially similar to those of the non-oxidative chars. The surface area of char was negligible at low temperatures, but increased dramatically to a maximum of 70 m{sup 2}g{sup -1} at 450{degree}C before decreasing at 500{degree}C. SEM analysis indicated that the pyrolysis of pectin occurred via softening and melting of the substrate followed by bubble formation. At high temperatures, surface etching followed by the appearance of crystal

Effects of Biomass Feedstocks and Gasification Conditions on the Physiochemical Properties of Char

Directory of Open Access Journals (Sweden)

Raymond L. Huhnke

2013-08-01

Full Text Available Char is a low-value byproduct of biomass gasification and pyrolysis with many potential applications, such as soil amendment and the synthesis of activated carbon and carbon-based catalysts. Considering these high-value applications, char could provide economic benefits to a biorefinery utilizing gasification or pyrolysis technologies. However, the properties of char depend heavily on biomass feedstock, gasifier design and operating conditions. This paper reports the effects of biomass type (switchgrass, sorghum straw and red cedar and equivalence ratio (0.20, 0.25 and 0.28, i.e., the ratio of air supply relative to the air that is required for stoichiometric combustion of biomass, on the physiochemical properties of char derived from gasification. Results show that the Brunauer-Emmett-Teller (BET surface areas of most of the char were 1–10 m2/g and increased as the equivalence ratio increased. Char moisture and fixed carbon contents decreased while ash content increased as equivalence ratio increased. The corresponding Fourier Transform Infrared spectra showed that the surface functional groups of char differed between biomass types but remained similar with change in equivalence ratio.

Isothermal CO2 Gasification Reactivity and Kinetic Models of Biomass Char/Anthracite Char

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Hai-Bin Zuo

2015-07-01

Full Text Available Gasification of four biomass chars and anthracite char were investigated under a CO2 atmosphere using a thermo-gravimetric analyzer. Reactivity differences of chars were considered in terms of pyrolysis temperature, char types, crystallinity, and inherent minerals. The results show that the gasification reactivity of char decreased with the increase of pyrolysis temperature. Char gasification reactivity followed the order of anthracite coal char (AC-char ˂ pine sawdust char (PS-char ˂ peanut hull char (PH-char ˂ wheat straw char (WS-char ˂ corncob char (CB-char under the same pyrolysis temperature. Two repesentative gas-solid models, the random pore model (RPM and the modified random pore model (MRPM, were applied to describe the reactive behaviour of chars. The results indicate RPM performs well to describe gasification rates of chars but cannot predict the phenomenon that there appears to exist a peak conversion for biomass chars at a high conversion rate, where the MRPM performs better.

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.

Structural and Compositional Transformations of Biomass Chars during Fast Pyrolysis

DEFF Research Database (Denmark)

Trubetskaya, Anna; Steibel, Markus; Spliethoff, Hartmut

In this work the physical and chemical transformations of biomass chars during fast pyrolysis, considered as a 2nd stage of combustion, has been investigated. Seven biomasses containing different amount of ash and organic components were reacted at up to 1673 K with high heating rates in a wire...

Advanced char burnout models for the simulation of pulverized coal fired boilers

Energy Technology Data Exchange (ETDEWEB)

T. Severin; S. Wirtz; V. Scherer [Ruhr-University, Bochum (Germany). Institute of Energy Plant Technology (LEAT)

2005-07-01

The numerical simulation of coal combustion processes is widely used as an efficient means to predict burner or system behaviour. In this paper an approach to improve CFD simulations of pulverized coal fired boilers with advanced coal combustion models is presented. In simple coal combustion models, first order Arrhenius rate equations are used for devolatilization and char burnout. The accuracy of such simple models is sufficient for the basic aspects of heat release. The prediction of carbon-in-ash is one aspect of special interest in the simulation of pulverized coal fired boilers. To determine the carbon-in-ash levels in the fly ash of coal fired furnaces, the char burnout model has to be more detailed. It was tested, in how far changing operating conditions affect the carbon-in-ash prediction of the simulation. To run several test cases in a short time, a simplified cellnet model was applied. To use a cellnet model for simulations of pulverized coal fired boilers, it was coupled with a Lagrangian particle model, used in CFD simulations, too. 18 refs., 5 figs., 5 tabs.

Burnout synergic or inhibiting effects in combustion assays of coal/sawdust blends

Energy Technology Data Exchange (ETDEWEB)

Ximena Garcia; Ximena Matus; Claudia Ulloa; Alfredo L. Gordon [University of Concepcion, Concepcion (Chile). Dept. of Chemical Engineering

2007-07-01

Characterization of chars and charcoal and combustion assays of coal/ pine sawdust blends were carried on to evaluate the burnout, under conditions similar to those found in pulverized coal combustion. A drop tube furnace (DTF) was used to generate chars from three coals of different rank (Bitsch, a lignite; Lemington, a bituminous HV coal; and LD, a semianthracite) and charcoal from sawdust (S). Burning profiles, as well as morphological and optical characterization of these chars were obtained and discussed. Pulverized samples of pure constituents and sawdust/coal blends (5, 10 and 20%wt of S) were burned in the DTF reactor. Samples of combustion residues were collected for characterization. Depending on blend composition and the rank of the coal being blended, positive and negative deviations with respect to the expected weighted average value of the burnout were measured. This behavior is related both, to the duration of the step by which simultaneous burning of char and charcoal take place, and to the sawdust content in the blend. The optical analysis of combustion residues supports this conclusion. 7 refs., 6 figs., 3 tabs.

Mechanism and Thermochemistry of Coal Char Oxidation and Desorption of Surface Oxides

DEFF Research Database (Denmark)

Levi, Gianluca; Causà, Mauro; Lacovig, Paolo

2017-01-01

The present study investigates the coal char combustion by a combination of thermochemical and X-ray photoemission spectroscopy (XPS) analyses. Thermoanalytical methods (differential thermogravimetry, differential scanning calorimetry, and temperature-programmed desorption) are used to identify...... the key reactive steps that occur upon oxidation and heating of coal char (chemisorption, structural rearrangement and switchover of surface oxides, and desorption) and their energetics. XPS is used to reveal the chemical nature of the surface oxides that populate the char surface and to monitor...... functionalities prevail. The rearrangement of epoxy during preoxidation goes together with activation of the more stable and less reactive carbon sites. Results are in good agreement with semi-lumped kinetic models of carbon oxidation, which include (1) formation of "metastable" surface oxides, (2) complex...

Fuel gas and char from pyrolysis of waste paper in a microwave plasma reactor

Energy Technology Data Exchange (ETDEWEB)

Khongkrapan, Parin; Thanompongchart, Patipat; Tippayawong, Nakorn; Kiatsiriroat, Tanongkiat [Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200 (Thailand)

2013-07-01

In this study, a microwave plasma reactor was used for pyrolysis of waste papers. The effects of different argon flow rates on char and gas generation were investigated. Changes in carbon and oxygen contents from those in paper to char were significant. Char yield of over 25 % was obtained with the heating value of about 38 MJ/kg. Average gas yield and total content of combustible fraction (CO, CH4 and H2) in the gas product were 2.56 m3/kg and 36 %, respectively. The heating value of gas product and carbon conversion efficiency of the process were maximum at 6.0 MJ/m3 and 73 %, respectively.

Combustion behaviour of ultra clean coal obtained by chemical demineralisation

Energy Technology Data Exchange (ETDEWEB)

F. Rubiera; A. Arenillas; B. Arias; J.J. Pis; I. Suarez-Ruiz; K.M. Steel; J.W. Patrick [Instituto Nacional del Carbon, CSIC, Oviedo (Spain)

2003-10-01

The increasing environmental concern caused by the use of fossil fuels and the concomitant need for improved combustion efficiency is leading to the development of new coal cleaning and utilisation processes. However, the benefits achieved by the removal of most mineral matter from coal either by physical or chemical methods can be annulled if poor coal combustibility characteristics are attained. In this work a high volatile bituminous coal with 6% ash content was subjected to chemical demineralisation via hydrofluoric and nitric acid leaching, the ash content of the clean coal was reduced to 0.3%. The original and treated coals were devolatilised in a drop tube furnace and the structure and morphology of the resultant chars was analysed by optical and scanning electron microscopies. The reactivity characteristics of the chars were studied by isothermal combustion tests in air at different temperatures in a thermogravimetric system. Comparison of the combustion behaviour and pollutant emissions of both coals was conducted in a drop tube furnace operating at 1000{sup o}C. The results of this work indicate that the char obtained from the chemically treated coal presents very different structure, morphology and reactivity behaviour than the char from the original coal. The changes induced by the chemical treatment increased the combustion efficiency determined in the drop tube furnace, in fact higher burnout levels were obtained for the demineralised coal.

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

Prediction of the burnout behaviour of chars derived from coal-biomass blends

Energy Technology Data Exchange (ETDEWEB)

Tao Wu; Mei Gong; Edward Lester [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering

2007-07-01

Nowadays, biomass has been considered an alternative fuel to coal and is being used in power plants to replace part of coal used. This study is to investigate the potential of burning biomass with coal and its impacts on burnout levels. Daw Mill coal was selected for burnout modelling together with three biomasses, Cereal, PKE and Olive Cake. Chars were prepared (75-106 micron) and characterised using image analysis methods as in input data into the char burnout model (ChB) which was adapted to allow the prediction of char burnout of biomass-coal blends under typical pf combustion conditions. The burnout performance of four blend compositions for each biomass were modelled (5%, 10%, 20% and 30%). In practice, the low heating-value of biomass produces a lower flame temperature which can lead to lower levels of char burn-out. The effect is closely linked with the type of biomass used. 36 refs., 4 figs., 1 tab.

Characterization of biomass combustion at high temperatures based on an upgraded single particle model

International Nuclear Information System (INIS)

Li, Jun; Paul, Manosh C.; Younger, Paul L.; Watson, Ian; Hossain, Mamdud; Welch, Stephen

2015-01-01

Highlights: • High temperature rapid biomass combustion is studied based on single particle model. • Particle size changes in devolatilization and char oxidation models are addressed. • Time scales of various thermal sub-processes are compared and discussed. • Potential solutions are suggested to achieve better biomass co-firing performances. - Abstract: Biomass co-firing is becoming a promising solution to reduce CO 2 emissions, due to its renewability and carbon neutrality. Biomass normally has high moisture and volatile contents, complicating its combustion behavior, which is significantly different from that of coal. A computational fluid dynamics (CFD) combustion model of a single biomass particle is employed to study high-temperature rapid biomass combustion. The two-competing-rate model and kinetics/diffusion model are used to model biomass devolatilization reaction and char burnout process, respectively, in which the apparent kinetics used for those two models were from high temperatures and high heating rates tests. The particle size changes during the devolatilization and char burnout are also considered. The mass loss properties and temperature profile during the biomass devolatilization and combustion processes are predicted; and the timescales of particle heating up, drying, devolatilization, and char burnout are compared and discussed. Finally, the results shed light on the effects of particle size on the combustion behavior of biomass particle

Coke, char and organic waste behaviour in the blast furnace with high injection rate

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Gudenau, H. W.

2003-10-01

Full Text Available Blast furnace operation with low coke rate, high amount of auxiliary hydrocarbons and use of nut coke causes a change in coke quality requirements. In particular, not burned in the raceway residues of injected substances (char and ash can influence the coke behaviour. Therefore combustion efficiency of various organic wastes with and without pulverized coal injection (PCI and coal char has been investigated under the raceway simulation conditions. Mixing of various substances improves their combustion efficiency. Study on coke gasification by carbon dioxide in the presence of char showed that with the increase of char concentration, coke strength reduction becomes smaller. The reactivity of char with CO₂ is higher than that of coke. Therefore char is consumed preferentially. In presence of injected char, total pore volume in coke and its wear resistance were increased. Coke reactivity and microstructure in the presence of various kinds of ash has been studied. Many ash spheres were observed on the surface of coke matrix and its size was dependent on ash properties.

La operación del horno alto con una tasa baja de coque, una cantidad elevada de hidrocarburos auxiliares y el empleo de coque calibrado, origina un cambio en las necesidades de calidad del coque. En particular, pueden influir en el comportamiento del coque los residuos inquemados en el raceway (cavidad enfrente a las toberas del horno de las sustancias que se inyectan (char y cenizas. El char es el residuo de carbón que se origina después que el carbón libera sus sustancias volátiles. Por tanto, se ha investigado la eficiencia de la combustión de varios residuos orgánicos con y sin inyección de carbón pulverizado (ICP y char, bajo las condiciones de simulación del raceway. La mezcla de varias sustancias mejora la eficiencia a la combustión. El estudio de la gasificación del coque por el dióxido de carbono en la

Numerical modeling of turbulent combustion and flame spread

Energy Technology Data Exchange (ETDEWEB)

Yan Zhenghua

1999-01-01

Theoretical models have been developed to address several important aspects of numerical modeling of turbulent combustion and flame spread. The developed models include a pyrolysis model for charring and non-charring solid materials, a fast narrow band radiation property evaluation model (FASTNB) and a turbulence model for buoyant flow and flame. In the pyrolysis model, a completely new algorithm has been proposed, where a moving dual mesh concept was developed and implemented. With this new concept, it provides proper spatial resolution for both temperature and density and automatically considers the regression of the surface of the non-charring solid material during its pyrolysis. It is simple, very efficient and applicable to both charring and non-charring materials. FASTNB speeds up significantly the evaluation of narrow band spectral radiation properties and thus provides a potential of applying narrow band model in numerical simulations of practical turbulent combustion. The turbulence model was developed to improve the consideration of buoyancy effect on turbulence and turbulent transport. It was found to be simple, promising and numerically stable. It has been tested against both plane and axisymmetric thermal plumes and an axisymmetric buoyant diffusion flame. When compared with the widely used standard buoyancy-modified {kappa} - {epsilon} model, it gives significant improvement on numerical results. These developed models have been fully incorporated into CFD (Computational Fluid Dynamics) code and coupled with other CFD sub-models, including the DT (Discrete Transfer) radiation model, EDC (Eddy Dissipation Concept) combustion model, flamelet combustion model, various soot models and transpired wall function. Comprehensive numerical simulations have been carried out to study soot formation and oxidation in turbulent buoyant diffusion flames, flame heat transfer and flame spread in fires. The gas temperature and velocity, soot volume fraction, wall

Effect of Ash on Oxygen Carriers for the Application of Chemical Looping Combustion to a High Carbon Char Effet des cendres sur l’activité des porteurs d’oxygène dans la combustion du charbon en boucle chimique

Directory of Open Access Journals (Sweden)

Rubel A.

2011-02-01

Full Text Available The application of Chemical Looping Combustion (CLC to solid fuels is being investigated at the University of Kentucky, Center for Applied Energy Research (CAER with the aim of the development of a Pressurized Chemical Looping Combustion/Gasification (PCLC/G process for the generation of electricity from coal. One important aspect of the CLC of solid fuel is the understanding of the effect of ash on the reactivity of Oxygen Carriers (OCs. The effect of ash on the redox capabilities of two different iron oxide OCs and on their ability to oxidize coal char was studied. To determine the effect of ash on the reactivity and recycle of the OCs through multiple redox cycles, fly ash from a coal-fired power plant was used. These experiments were performed in a TGMS system using 500 mg of ash/OC mixtures containing different ash concentrations up to 75%. The reducing gas was composed of 10% H2, 15% CO, 20% CO2, and a balance of Ar and the oxidizing gas was 20% O2 in Ar. Oxidation/reductions were carried to near completion. The ash was found to contain OC activity related to inherent iron present in the ash confirmed by XRD. This resulted in increased weight gain/loss on oxidation/reduction. The rate of oxidation/reduction increased with ash concentration due to increased porosity of the OC/ash mixture and better access of the reactive gases to the OC target sites. The two OCs were then used to combust a beneficiated coal char in the TGMS with the only oxygen supplied by an iron oxide OC. The starting mixture was 10% char and 90% of one of two OCs studied. The spent material containing reduced OC and ash was re-oxidized and 10% more char was added for a second reduction of the OC and oxidation of the added char. This procedure was repeated for 5 cycles increasing the ash concentrations from 5 to 25% in the char/ash/OC mixture. Carbon removal was 92 to 97.8 and 97.3 to 99.7% for the two different iron oxide OCs tested. Ash was not detrimental to the

Characterization of char derived from various types of solid wastes from the standpoint of fuel recovery and pretreatment before landfilling

International Nuclear Information System (INIS)

Hwang, I.H.; Matsuto, T.; Tanaka, N.; Sasaki, Y.; Tanaami, K.

2007-01-01

Carbonization is a kind of pyrolysis process to produce char from organic materials under an inert atmosphere. In this work, chars derived from various solid wastes were characterized from the standpoint of fuel recovery and pretreatment of waste before landfilling. Sixteen kinds of municipal and industrial solid wastes such as residential combustible wastes, non-combustible wastes, bulky wastes, construction and demolition wastes, auto shredder residue, and sludges were carbonized at 500 deg. C for 1 h under nitrogen atmosphere. In order to evaluate the quality of char as fuel, proximate analysis and heating value were examined. The composition of raw waste had a significant influence on the quality of produced char. The higher the ratio of woody biomass in waste, the higher heating value of char produced. Moreover, an equation to estimate heating value of char was developed by using the weight fraction of fixed carbon and volatile matter in char. De-ashing and chlorine removal were performed to improve the quality of char. The pulverization and sieving method seems to be effective for separation of incombustibles such as metal rather than ash. Most char met a 0.5 wt% chlorine criterion for utilization as fuel in a shaft blast furnace after it was subjected to repeated water-washing. Carbonization could remove a considerable amount of organic matter from raw waste. In addition, the leaching of heavy metals such as chrome, cadmium, and lead appears to be significantly suppressed by carbonization regardless of the type of raw waste. From these results, carbonization could be considered as a pretreatment method for waste before landfilling, as well as for fuel recovery

Prediction and validation of burnout curves for Goettelborn char using reaction kinetics determined in shock tube experiments

Energy Technology Data Exchange (ETDEWEB)

Moors, J.H.J.; Banin, V.E.; Haas, J.H.P.; Weber, R.; Veefkind, A. [Eindhoven University of Technology, Eindhoven (Netherlands). Dept. of Applied Physics

1999-01-01

Using a shock tube facility the combustion characteristics of pulverised char ({lt} 10 {mu}m) were measured. A prediction was made for the burnout behaviour of a commercial sized char particle (75-90 {mu}m) in different ambient conditions using a `pseudo kinetic` approach. In this approach the kinetic rate of a surface containing micro pores is determined and these `pseudo kinetics` are then applied to the larger particle not taking into account the micro pores. Comparison of the predictions with measurements done with an isothermal plug flow reactor showed this approach to be valid within experimental error for low burnout. A linear decrease of the kinetic reaction rate with burnout is shown to predict the burnout behaviour in the complete range of burnout. A possible explanation for this linear decrease could be a growing fraction of non-combustible material in the char particles during burnout. 11 refs., 6 figs., 2 tabs.

Mixed Waste Treatment Using the ChemChar Thermolytic Detoxification Technique

International Nuclear Information System (INIS)

Kuchynka, D.J.

1997-01-01

This R and D program addresses the treatment of mixed waste employing the ChemChar Thermolytic Detoxification process. Surrogate mixed waste streams will be treated in a four inch diameter, continuous feed, adiabatic reactor with the goal of meeting all regulatory treatment levels for the contaminants in the surrogates with the concomitant production of contaminant free by-products. Successful completion of this program will show that organic contaminants in mixed waste surrogates will be converted to a clean, energy rich synthesis gas capable of being used, without further processing, for power or heat generation. The inorganic components in the surrogates will be found to be adsorbed on a macroporous coal char activated carbon substrate which is mixed with the waste prior to treatment. These contaminants include radioactive metal surrogate species, RCRA hazardous metals and any acid gases formed during the treatment process. The program has three main tasks that will be performed to meet the above objectives. The first task is the design and construction of the four inch reactor at Mirage Systems in Sunnyvale, CA. The second task is production and procurement of the activated carbon char employed in the ChemChartest runs and identification of two surrogate mixed wastes. The last task is testing and operation of the reactor on char/surrogate waste mixtures to be performed at the University of Missouri. The deliverables for the project are a Design Review Report, Operational Test Plan, Topical Report and Final Report. This report contains only the results of the design and construction carbon production-surrogate waste identification tasks.Treatment of the surrogate mixed wastes has just begun and will not be reported in this version of the Final Report. The latter will be reported in the final version of the Final Report

Influence of char texture and volatile matter content on NO emissions

Energy Technology Data Exchange (ETDEWEB)

Arenillas, A.; Rubiera, F.; Parra, J.B.; Moreno, A.H.; Pis, J.J. [Inst. National Vacional del Carbon, Oviedo (Spain)

1997-12-31

A low volatile bituminous coal was pyrolysed in a quartz reactor under nitrogen at different heating rates (5, 10, 50 and 150 C/min) up to a final temperature of 850 C. Textural characterisation (mercury porosimetry, adsorption isotherms of N{sub 2} and CO{sub 2}, ASA) of the chars was carried out in order to study the influence of textural properties on char reactivity and NO emissions. The role of volatile matter content in the emission of nitrogen compounds was also investigated. A thermogravimetric analyser linked to a quadrupole mass spectrometer (TG-MS) was used to study the compounds evolved during pyrolysis and combustion. (orig.)

Behaviour, capture and inertization of some trace elements during combustion of refuse-derived char from municipal solid waste

Energy Technology Data Exchange (ETDEWEB)

Vassilev, S.V.; Braekman-Danheux, C.; Laurent, P.; Thiemann, T.; Fontana, A. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Central Lab. of Mineralogy and Crystallography

1999-08-01

An investigation of refuse-derived char (RDC) generated by thermolysis of municipal solid waste (MSW) was undertaken to elucidate the behaviour of some toxic and potentially toxic trace elements (Cr, Cu, Mn, Ni, Pb, Sb and Zn) plus Fe during combustion of RDC. About 87% of Sb, 66% of Pb, 60% of Cu and significant parts of Fe{gt}Zn{gt}Ni{gt}Mn{gt}Cr from the RDC are volatile at 1200{degree}C, and their behaviour in the temperature interval 500-1200{degree}C is characterized. The use of sorbents (zeolite, kaolinite, montmorillonite, coals enriched in kaolinite and calcite, and lime plus portlandite) for capture, solidification and inertization of the most volatile elements during combustion of RDC is also described. Perspective sorbents and inertants for a retention of the most volatile Pb, Sb and Cu in RDC ash are kaolinite and montmorillonite or coals enriched in these minerals. In addition, when there is an effective RDC washing (dechlorination and desulphurization), the use of sorbents for capture of some metals could be reduced or even avoided. Recommendations are given for RDC utilization and improvisation of the collection, separation procedures and removal efficiency of some heavy-metal, chloride and sulphate compounds from MSW and RDC prior to their use. The results show that a long-term strategy based on detailed understanding of the source, formation, behaviour and fate of the elements and their modes of occurrence in MSW, RDC and combustion waste residues is required in order to validate a perspective waste pyrolytic processes development. 55 refs., 3 figs., 6 tabs.

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.

Oxy-Fuel Combustion of Coal

DEFF Research Database (Denmark)

Brix, Jacob

This Ph.D. thesis describes an experimental and modeling investigation of the thermal conversion of coal and an experimental investigation of the emission of NO from char combustion in O2/N2 and O2/CO2 atmospheres. The motivation for the work has been the prospective use of the technology “Oxy......-Fuel Combustion” as a mean of CO2 abatement in large scale energy conversion. Entrained Flow Reactor (EFR) experiments have been conducted in O2/N2 and O2/CO2 mixtures in the temperature interval 1173 K – 1673 K using inlet O2 concentrations between 5 – 28 vol. %. Bituminous coal has been used as fuel in all....... % it was found that char conversion rate was lowered in O2/CO2 compared to O2/N2. This is caused by the lower diffusion coefficient of O2 in CO2 (~ 22 %) that limits the reaction rate in zone III compared to combustion in O2/N2. Using char sampled in the EFR experiments ThermoGravimetric Analyzer (TGA...

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...

Development of a dynamic drying model for for a combustion grate; Framtagande av en dynamisk torkmodell foer en foerbraenningsrost

Energy Technology Data Exchange (ETDEWEB)

Broden, Henrik; Ramstroem, Erik [TPS Termiska Processer AB, Nykoeping (Sweden)

2005-02-01

Combustion of wet wood fuel at high grate loading requires good control of the burnout position to avoid unacceptably high content of unburnt fuel in the ash. To control the burn-out position, control actions on the grate feeding must be made with sufficient range and anticipation. One way to improve the understanding of the dynamic fuel bed response on changes in control system parameters is mathematical modelling. The research task has been to develop a mathematical model of a drying fuel bed on a moving grate. The model includes a simplified description of drying, pyrolysis and char combustion and also pusher/grate movement and primary air flow/distribution. The objectives of the project have been to establish the most likely mechanism for drying and ignition of a wet fuel bed on a moving grate by the use of mathematical modelling and also to create a tool for simulation of control system step responses. The target group for the project are individuals working in the area of control system development of grate fired boilers. Three different assumptions on drying and ignition front propagation in a bio fuel bed with 50 and 53 % moisture have been modelled: 1. Drying and ignition from an underlying char layer in a co-current primary air flow 2. Drying and ignition from an overlaying char layer in counter-current primary air flow 3. Drying and ignition from both an underlying and overlaying char layer The model with drying and ignition driven by an underlying char layer is the projection, which gives the fastest and time-wise the most similar course to what one normally sees in grate fired boilers. The model with drying and ignition from above is not capable of upholding a stable diffusion controlled burning char layer since too small quantities of heat is transferred into the fuel bed. The model with drying and ignition from both directions results in similar combustion rate as the first model. The similar course of combustion is due to the energy for drying

Impact of Char Livelihood Program (CLP of Char land Dwellers around the Char Areas in Sirajgonj District of Bangladesh

Directory of Open Access Journals (Sweden)

Mohammad Anamul Haque

2017-12-01

Full Text Available In an attempt to address the impact of Char Livelihood Program (CLP of Char land dwellers, this study is carried out to examine the livelihood and income generation activities of the people of Bangala Char in Sirajgonj District, due to intervention of Char Livelihood Program (CLP by the DFID of United Kingdom (UK. The research question of the study was whether and to what extent the Char Livelihood Program (CLP brings any changes in the livelihood and income generation activities of the people of Bangala Char. Two areas have been studied, one area is under the intervention of the project (Bangala Char as program intervention area another is not under the program intervention (Sonatoni Char as control area. Both areas have been chosen of the vicinity of similar characteristics and geographical location for the ease of addressing the problems and analytical comparison. The study uses semi-structured questionnaire for household interview both for the program intervention and the control area as random sampling basis. This study a total of 96 households’ interviews conducted of the study areas among them 48 households from Bangala Char and 48 households from the Sonatoni Char (control area. Primary data collected from house hold respondent and secondary data were used from published and unpublished sources. Four variables are access to land, income and assets , food security and vulnerability identified and the analysis shows that access to land resources among the char dwellers has established legal ownership and entitlement of land and resolve the crisis of permanent settlement which bring change in livelihood in terms of access to land resources to some extent. The islands of char dwellers are in general disadvantaged with respect to their mainland counterparts in terms of physical isolation and vulnerability to flooding and erosion have created seasonal migration and higher dependency on traditional money lenders for accessing credit supply

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...

Strategy for Passivating Char Efficiently at the Pilot Scale

Energy Technology Data Exchange (ETDEWEB)

Dunning, Timothy C [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-01-18

Fast pyrolysis is a promising pathway for the commercialization of liquid transportation fuels from biomass. Fast pyrolysis is performed at moderate heat (450-600 degrees Celcius) in an oxygen-deficient environment. One of the products of fast pyrolysis is biochar, which is often used as a heat source or as a soil amendment. Biochar is a partially reacted solid that is created in the production of bio-oil during fast pyrolysis. Biochar produced at these conditions contains significant quantities of carbon that adsorb oxygen when exposed to air. Biochar adsorption of oxygen is an exothermic process that may generate sufficient heat for combustion in ambient air. Biochar is also a self-insulating material which compounds the effects of heat generated internally. These factors lead to safety concerns and material handling difficulties. The Thermochemical Process Development Unit at the National Renewable Energy Laboratory operates a pilot plant that may be configured for fast pyrolysis, gasification, and will be introducing catalytic fast pyrolysis capabilities in 2018. The TCPDU designed and installed a system to introduce oxygen to collected biochar systematically for a controlled passivation. Biochar is collected and cooled in an oxygen deficient environment during fast pyrolysis. Oxygen is then introduced to the biochar on a mass flow basis. A sparger imbedded within the biochar sample near the bottom of the bed flows air diluted with nitrogen into the char bed, and excess gasses are removed from the top of the collection drum, above the char bed. Pressure within the collection drum is measured indicating adequate flow through filters. Sample weight is recorded before and after passivation. During passivation, temperature is measured at 18 points within the char bed. Oxygen content and temperature are measured leaving the char bed. Maximum temperature parameters were established to ensure operator safety during biochar passivation. Extensive passivation data was

Development of an advanced, continuous mild-gasification process for the production of coproducts. Report for Task 4.8, Decontamination and disassembly of the mild-gasification and char-to-carbon PRUs and disposal of products from testing

Energy Technology Data Exchange (ETDEWEB)

Merriam, N.W. [Western Research Inst., Laramie, WY (United States); Jha, Mahesh C. [AMAX Research and Development Center, Golden, CO (United States)

1991-11-01

This report contains descriptions of mild-gasification and char-to-carbon process research units (PRUS) used by WRI and AMAX R&D Center to conduct tests under contract AC21-87MC24268. Descriptions of materials produced during those tests are also contained herein. Western Research Institute proposes to dispose of remaining fines and dried coal by combustion and remaining coal liquids by incineration during mid-1992. The mild-gasification PRU will be used for additional tests until 1993, at which time WRI proposes to decontaminate and disassemble the PRU. AMAX R&D Center intends to return the spent char, any remaining feed char, and unusable product carbon to the Eagle Butte Mine near Gillette, Wyoming, from where the coal originally came. The solid products will be added to the mine`s coal product stream. Coal liquids collected from condensers will be concentrated and sent to a local oil and solvent recycling company where the liquids will be burned as fuel. The char-to-carbon PRU will be operated periodically until 1993 when the plant will be decontaminated and disassembled.

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....

Combustion behavior of different kinds of torrefied biomass and their blends with lignite.

Science.gov (United States)

Toptas, Asli; Yildirim, Yeliz; Duman, Gozde; Yanik, Jale

2015-02-01

In this study, the combustion behavior of different kinds of torrefied biomass (lignocellulosic and animal wastes) and their blends with lignite was investigated via non-isothermal thermogravimetric method under air atmosphere. For comparison, combustion characteristics of raw biomasses were also determined. Torrefaction process improved the reactivity of char combustion step of biomasses. Characteristic combustion parameters for blends showed non-additivity behavior. It was found that the mixture of torrefied biomasses and lignite at a ratio of 1:1 had a lower ignition and burnout temperature than the coal-only sample. Although no interactions were observed between the lignite and torrefied biomass at initial step of combustion, a certain degree of interaction between the components occurred at char combustion step. Kinetic parameters of combustion were calculated by using the Coats Redfern model. Overall, this study showed that poultry litters can be used as a substitute fuel in coal/biomass co-firing systems by blending with lignocellulosic biomass. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characteristics and synergistic effects of co-combustion of carbonaceous wastes with coal.

Science.gov (United States)

Onenc, Sermin; Retschitzegger, Stefan; Evic, Nikola; Kienzl, Norbert; Yanik, Jale

2018-01-01

This study presents combustion behavior and emission results obtained for different fuels: poultry litter (PL) and its char (PLC), scrap tires (ST) and its char (STC) and blends of char/lignite (PLC/LIG and STC/LIG). The combustion parameters and emissions were investigated via a non-isothermal thermogravimetric method and experiments in a lab-scale reactor. Fuel indexes were used for the prediction of high temperature corrosion risks and slagging potentials of the fuels used. The addition of chars to lignite caused a lowering of the combustion reactivity (anti-synergistic effect). There was a linear correlation between the NO x emissions and the N content of the fuel. The form of S and the concentrations of alkali metals in the fuel had a strong effect on the extent of SO 2 emissions. The use of PL and PLC in blends reduced SO 2 emissions and sulphur compounds in the fly ash. The 2S/Cl ratio in the fuel showed that only PLC and STC/PLC would show a risk of corrosion during combustion. The ratio of basic to acidic oxides in fuel indicated that ST, STC and STC/LIG have low slagging potential. The molar (Si+P+K)/(Ca+Mg) ratio, which was used for PL, PLC and PLC containing blends, showed that the ash melting temperatures of these fuels would be higher than 1000 °C. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synergistic Effect of Co-utilization of Coal and Biomass Char: An Overview

Science.gov (United States)

Paiman, M. E. S.; Hamzah, N. S.; Idris, S. S.; Rahman, N. A.; Ismail, K.

2018-05-01

Global concerns on impact of greenhouse gases emission, mostly released from coal-fired power plant, and the depletion of fossil fuel particularly coal, has led the production of electricity from alternatives resources such as co-utilization technologies. Previous studies proved that the co-utilization of coal and biomass/biomass chars has significantly reduced the emission of greenhouse gases either during the pyrolysis, combustion or gasification process in laboratories, pilots as well as in the industrial scales. Interestingly, most of the studies reported the presence of synergistic effect during the co-utilization processes particularly between coal and biomass char while some are not. Biomass chars were found to have porous and highly disorder carbon structure and belong to the class of most reactive carbon material, resulting to be more reactive than those hard coal and lignite. Up to date, microwave assisted pyrolysis is one of the best and latest techniques employed to produce better quality of biomass chars and it is also reduce the processing cost. Lot of works has been done regarding on the existence of synergistic effects during its co-utilization. However, the knowledge is limited to thermal and product characteristics so far. Even so, the specific reasons behind its existence are yet to understand well. Therefore, in this paper, the emphasis will be given on the synergistic effects on emission characteristics of co-utilization of coal and biomass chars so that it can be apply in energy-based industries to help in reduction of the greenhouse gases emission.

Controls upon biomass losses and char production from prescribed burning on UK moorland.

Science.gov (United States)

Worrall, Fred; Clay, Gareth D; May, Richard

2013-05-15

Prescribed burning is a common management technique used across many areas of the UK uplands. However, there are few data sets that assess the loss of biomass during burning and even fewer data on the effect of burning on above-ground carbon stocks and production of char. During fire the production of char occurs which represents a transfer of carbon from the short term bio-atmospheric cycle to the longer term geological cycle. However, biomass is consumed leading to the reduction in litter formation which is the principal mechanism for peat formation. This study aims to solve the problem of whether loss of biomass during a fire is ever outweighed by the production of refractory forms of carbon during the fire. This study combines both a laboratory study of char production with an assessment of biomass loss from a series of field burns from moorland in the Peak District, UK. The laboratory results show that there are significant effects due to ambient temperature but the most important control on dry mass loss is the maximum burn temperature. Burn temperature was also found to be linearly related to the production of char in the burn products. Optimisation of dry mass loss, char production and carbon content shows that the production of char from certain fires could store more carbon in the ecosystem than if there had been no fire. Field results show that approximately 75% of the biomass and carbon were lost through combustion, a figure comparable to other studies of prescribed fire in other settings. Char-C production was approximately 2.6% of the carbon consumed during the fire. This study has shown that there are conditions (fast burns at high temperatures) under which prescribed fire may increase C sequestration through char production and that these conditions are within existing management options available to practitioners. Copyright © 2013 Elsevier Ltd. All rights reserved.

The release of nitrogen in coal combustion and pyrolysis

International Nuclear Information System (INIS)

Varey, J.E.; Hindmarsh, C.J.; Thomas, K.M.

1994-01-01

Environmental aspects of coal utilization are a major concern. Recent advances in the development of low NO x burners and the emerging technologies of fluidized bed combustion have led to the identification of coal char nitrogen as the major contributor to the nitrogen oxides released during combustion. The temperature programmed combustion and pyrolysis of a series of coals covering a wide range of rank have been investigated. In addition, maceral concentrates have been investigated to assess the variation in the combustion behavior and the release of nitrogen in the pyrolysis and combustion of macerals. This investigation has involved the use of thermogravimetric analysis - mass spectrometry (TG-MS) with two sampling options: (1) ∼1cm from the sample and (2) at the exit of the TG. The former allows reactive species to be identified in the combustion of the coals. These temperature programmed combustion results have been compared with similar measurements carried out at the exit of the TG where the products are at equilibrium. In addition, pyrolysis studies have been carried out under similar conditions. The results show that reactive intermediate species such as HCN, (CN) 2 , COS etc. can be detected in the combustion products. The evolution of these species during combustion are compared with the pyrolysis products of the coal. The results are discussed in relation to the structure of the coals and the conversion of volatile species and char nitrogen to nitrogen oxides

Measurements of Gasification Characteristics of Coal and Char in CO2-Rich Gas Flow by TG-DTA

Directory of Open Access Journals (Sweden)

Zhigang Li

2013-01-01

Full Text Available Pyrolysis, combustion, and gasification properties of pulverized coal and char in CO2-rich gas flow were investigated by using gravimetric-differential thermal analysis (TG-DTA with changing O2%, heating temperature gradient, and flow rate of CO2-rich gases provided. Together with TG-DTA, flue gas generated from the heated coal, such as CO, CO2, and hydrocarbons (HCs, was analyzed simultaneously on the heating process. The optimum O2% in CO2-rich gas for combustion and gasification of coal or char was discussed by analyzing flue gas with changing O2 from 0 to 5%. The experimental results indicate that O2% has an especially large effect on carbon oxidation at temperature less than 1100°C, and lower O2 concentration promotes gasification reaction by producing CO gas over 1100°C in temperature. The TG-DTA results with gas analyses have presented basic reference data that show the effects of O2 concentration and heating rate on coal physical and chemical behaviors for the expected technologies on coal gasification in CO2-rich gas and oxygen combustion and underground coal gasification.

Pyrolysis of flax straw: Characterization of char, liquid, and gas as fuel

Science.gov (United States)

Tushar, Mohammad Shahed Hasan Khan

The demand for energy continues to outstrip its supply and necessitates the development of renewable energy options. Biomass has been recognized as a major renewable energy source to supplement the declining fossil fuel source of energy. It is the most popular form of renewable energy and, currently, biofuel production is becoming more promising. Being carbon neutral, readily available, and low in sulphur content makes biomass a very promising source of renewable energy. In the present research, both the isothermal and non-isothermal pressurized pyrolysis of flax straw is studied for the first time. In case of isothermal pyrolysis, the influence of pyrolysis temperature and reaction time on char yield and morphology was investigated. The applied pyrolysis temperature was varied between 300 and 500°C. The reaction time was varied from 15 to 60 min. The char yield was found to decrease as pyrolysis temperature and reaction time increased. The char structure and surface morphology were thoroughly investigated by means of x-ray diffraction (XRD), temperature-programmed oxidation (TPO), and scanning electron microscopy (SEM). The degree of porosity and graphitization increased as pyrolysis temperature and time increased. In fact, the experiment performed at 500°C for 1h duration did not yield any char; only residual ash could be obtained. The TPO studies on the char samples corroborated the XRD findings and showed the presence of two types of carbon, namely, amorphous filamentous carbon and graphitic carbon. A thermogravimetric analysis (TGA) of the char was performed to gain an understanding of combustion kinetics and reactivity. It implied that the reactivity of the char decreases as temperature increases, and this finding is well supported by the TPO, TGA, SEM, and XRD characterization data. Furthermore, an empirical global model was devised based on the power law to estimate activation energy and other kinetic parameters. For the non-isothermal pressurized

Catalytic Pyrolysis of Tar Model Compound with Various Bio-Char Catalysts to Recycle Char from Biomass Pyrolysis

Directory of Open Access Journals (Sweden)

Jinmiao Liu

2016-03-01

Full Text Available Tar and char can be regarded as unwanted byproducts during the gasification process. In this study, three types of catalyst, i.e., biomass char (bio-char, nickel supported on biomass (Ni+bio-char, and nickel supported on bio-char (bio-char+Ni, were studied to compare the catalytic effects of different preparation methods on tar model compound removal. The structural characteristics of the three catalysts were also investigated by X-ray diffraction (XRD, scanning electron microscopy (SEM, and Brunauer-Emmett-Teller (BET methods. The results revealed that Ni+bio-char catalyst showed much higher activity for the reformation of toluene (C7H8 as a tar model compound than the other two catalysts. Toluene could be completely converted to small gas molecules at a conversion rate of 99.92% at 800 °C, and the maximum yield of gas was 432 mL/(mL C7H8. In particular, the H2 and CH4 yields were 339 and 85 mL/(mL C7H8 at 850 °C, respectively. An N2 absorption-desorption experiment demonstrated that the specific surface area of Ni+bio-char was 32.87 times that of bio-char and 8.39 times that of bio-char+Ni. Moreover, metallic nickel (Ni0 particles could be generated in the carbon matrix of Ni+bio-char catalyst. SEM analysis confirmed that the Ni+bio-char catalyst had a more porous structure. Nickel supported on biomass might be a promising catalyst for tar reformation because of its excellent catalytic activities.

Combustion characteristics and air pollutant formation during oxy-fuel co-combustion of microalgae and lignite.

Science.gov (United States)

Gao, Yuan; Tahmasebi, Arash; Dou, Jinxiao; Yu, Jianglong

2016-05-01

Oxy-fuel combustion of solid fuels is seen as one of the key technologies for carbon capture to reduce greenhouse gas emissions. The combustion characteristics of lignite coal, Chlorella vulgaris microalgae, and their blends under O2/N2 and O2/CO2 conditions were studied using a Thermogravimetric Analyzer-Mass Spectroscopy (TG-MS). During co-combustion of blends, three distinct peaks were observed and were attributed to C. vulgaris volatiles combustion, combustion of lignite, and combustion of microalgae char. Activation energy during combustion was calculated using iso-conventional method. Increasing the microalgae content in the blend resulted in an increase in activation energy for the blends combustion. The emissions of S- and N-species during blend fuel combustion were also investigated. The addition of microalgae to lignite during air combustion resulted in lower CO2, CO, and NO2 yields but enhanced NO, COS, and SO2 formation. During oxy-fuel co-combustion, the addition of microalgae to lignite enhanced the formation of gaseous species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improved Recovery Boiler Performance Through Control of Combustion, Sulfur, and Alkali Chemistry

Energy Technology Data Exchange (ETDEWEB)

Baxter, Larry L.

2008-06-09

This project involved the following objectives: 1. Determine black liquor drying and devolatilization elemental and total mass release rates and yields. 2. Develop a public domain physical/chemical kinetic model of black liquor drop combustion, including new information on drying and devolatilization. 3. Determine mechanisms and rates of sulfur scavenging in recover boilers. 4. Develop non-ideal, public-domain thermochemistry models for alkali salts appropriate for recovery boilers 5. Develop data and a one-dimensional model of a char bed in a recovery boiler. 6. Implement all of the above in comprehensive combustion code and validate effects on boiler performance. 7. Perform gasification modeling in support of INEL and commercial customers. The major accomplishments of this project corresponding to these objectives are as follows: 1. Original data for black liquor and biomass data demonstrate dependencies of particle reactions on particle size, liquor type, gas temperature, and gas composition. A comprehensive particle submodel and corresponding data developed during this project predicts particle drying (including both free and chemisorbed moisture), devolatilization, heterogeneous char oxidation, char-smelt reactions, and smelt oxidation. Data and model predictions agree, without adjustment of parameters, within their respective errors. The work performed under these tasks substantially exceeded the original objectives. 2. A separate model for sulfur scavenging and fume formation in a recovery boiler demonstrated strong dependence on both in-boiler mixing and chemistry. In particular, accurate fume particle size predictions, as determined from both laboratory and field measurements, depend on gas mixing effects in the boilers that lead to substantial particle agglomeration. Sulfur scavenging was quantitatively predicted while particle size required one empirical mixing factor to match data. 3. Condensed-phase thermochemistry algorithms were developed for salt

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

Proceedings of IEA combustion 2009 : IEA 31. task leaders meeting on energy conservation and emissions reduction in combustion

International Nuclear Information System (INIS)

2009-01-01

The International Energy Agency (IEA) supports research and development in energy technology. This meeting provided a forum to discuss combustion processes, which is fundamental to achieving further improvements in fuel use efficiency, reducing the production of pollutants such as nitrogen oxides, and facilitating the transition to alternative fuels. The presentations demonstrated recent studies in improving the efficiency and fuel flexibility of automotive engines; improving the performance of industrial furnaces; emissions formation and control mechanisms; and fuel injection and fuel/air mixing. The conference also highlighted studies involving hydrogen combustion, alternative fuels, particulate diagnostics, fuel sprays, gas turbines, and advanced combustion processes such as homogeneous charge compression ignition (HCCI). The sessions were entitled: HCCI fuels; sprays; nanoparticle diagnostics; alternative fuels; hydrogen internal combustion engines; turbines; energy security; and collaborative task planning. All 45 presentations from the conference have been catalogued separately for inclusion in this database. refs., tabs., figs.

Recycling of rubber tires in electric arc furnace steelmaking: simultaneous combustion of metallurgical coke and rubber tyres blends

Energy Technology Data Exchange (ETDEWEB)

Magdalena Zaharia; Veena Sahajwalla; Byong-Chul Kim; Rita Khanna; N. Saha-Chaudhury; Paul O' Kane; Jonathan Dicker; Catherine Skidmore; David Knights [University of New South Wales, Sydney, NSW (Australia). School of Materials Science and Engineering

2009-05-15

The present study investigates the effect of addition of waste rubber tires on the combustion behavior of its blends with coke for carbon injection in electric arc furnace steelmaking. Waste rubber tires were mixed in different proportions with metallurgical coke (MC) (10:90, 20:80, 30:70) for combustion and pyrolysis at 1473 K in a drop tube furnace (DTF) and thermogravimetric analyzer (TGA), respectively. Under experimental conditions most of the rubber blends indicated higher combustion efficiencies compared to those of the constituent coke. In the early stage of combustion the weight loss rate of the blends is much faster compared to that of the raw coke due to the higher volatile yield of rubber. The presence of rubber in the blends may have had an impact upon the structure during the release and combustion of their high volatile matter (VM) and hence increased char burnout. Measurements of micropore surface area and bulk density of the chars collected after combustion support the higher combustion efficiency of the blends in comparison to coke alone. The surface morphology of the 30% rubber blend revealed pores in the residual char that might be attributed to volatile evolution during high temperature reaction in oxygen atmosphere. Physical properties and VM appear to have a major effect upon the measured combustion efficiency of rubber blends. The study demonstrates that waste rubber tires can be successfully co-injected with metallurgical coke in electric arc furnace steelmaking process to provide additional energy from combustion. 44 refs., 11 figs., 2 tabs.

Fuel reactivity and release of pollutants and alkali vapours in pressurized combustion for combined cycle power generation

Energy Technology Data Exchange (ETDEWEB)

Aho, M.; Haemaelaeinen, J.; Paakkinen, K.; Rantanen, J. [VTT Energy, Jyvaeskylae (Finland); Hernberg, R.; Haeyrinen, V.; Joutsenoja, T. [Tampere Univ. of Technology (Finland). Lab. of Plasma Technology

1996-12-01

This project forms a part of the overall Pressurized Power Coal Combustion Project Area (PPFC) which aims at an assessment of the viability and technical merits of pressurized pulverized coal combustion, in an atmosphere of recycled flue gas and oxygen in a coordinated and harmonized programme. The objective of the research at Technical Research Centre of Finland (VTT) and Tampere University of Technology (TUT) is aimed at determining the consequences of solid fuel burning in a mixture of oxygen and recycled flue gases. Combustion conditions of a pressurized entrained flow of pulverized coal and char particles in PEFR are determined with high precision. The effects of experimental parameters on the formation of nitrogen oxides (N{sub 2}O, NO and NO{sub 2}) and gaseous alkali compounds (indicated as NaX(g) and KX(g)) are studied. An effective on-line analysis method for vaporised Na and K compounds was developed. The dependency between particle temperatures and the vaporisation of Na and K was measured with three coals. The results show that alkali removal before gas turbines is always necessary with these coals if combusted in combined cycles. Pressure decreases the formation of NO and has usually no clear effect on the formation of N{sub 2}O. The order of NO/N{sub 2}O ratios correspond to fuel-O/fuel-N ratios. Increase of PO{sub 2} (oxygen concentration) of combustion gas increases the formation of NO{sub 2}. Remarkable concentrations of NO{sub 2} were often measured at high PO{sub 2} at 800-850 deg C. Therefore, NO{sub 2} should be measured from pressurized fluidized bed reactors. Some trends of the formation of NO{sub 2} with coal differ clearly from those with its parent char: N{sub 2}O formation is not strongly temperature dependent with char, and the concentrations of N{sub 2}O formed from char are much lower than those of coal. PO{sub 2} does not effect on the formation of NO from char in the studied range

The influence of wildfire severity on soil char composition and nitrogen dynamics

Science.gov (United States)

Rhoades, Charles; Fegel, Timothy; Chow, Alex; Tsai, Kuo-Pei; Norman, John, III; Kelly, Eugene

2017-04-01

Forest fires cause lasting ecological changes and alter the biogeochemical processes that control stream water quality. Decreased plant nutrient uptake is the mechanism often held responsible for lasting post-fire shifts in nutrient supply and demand, though other upland and in-stream factors also likely contribute to elevated stream nutrient losses. Soil heating, for example, creates pyrogenic carbon (C) and char layers that influence C and nitrogen (N) cycling. Char layer composition and persistence vary across burned landscapes and are influenced first by fire behavior through the temperature and duration of combustion and then by post-fire erosion. To evaluate the link between soil char and stream C and N export we studied areas burned by the 2002 Hayman Fire, the largest wildfire in Colorado, USA history. We compared soil C and N pools and processes across ecotones that included 1) unburned forests, 2) areas with moderate and 3) high wildfire severity. We analyzed 1-2 cm thick charred organic layers that remain visible 15 years after the fire, underlying mineral soils, and soluble leachate from both layers. Unburned soils released more dissolved organic C and N (DOC and DON) from organic and mineral soil layers than burned soils. The composition of DOC leachate characterized by UV-fluorescence, emission-excitation matrices (EEMs) and Fluorescence Regional Integration (FRI) found similarity between burned and unburned soils, underscoring a common organic matter source. Humic and fulvic acid-like fractions, contained in regions V and III of the FRI model, comprised the majority of the fluorescing DOM in both unburned and char layers. Similarity between two EEMs indices (Fluorescence and Freshness), further denote that unburned soils and char layers originate from the same source and are consistent with visual evidence char layers contain significant amounts of unaltered OM. However, the EEMs humification index (HIX) and compositional analysis with pyrolysis GCMS

Predicting the combustion kinetics of Chinese coals

Energy Technology Data Exchange (ETDEWEB)

Niksa, Stephen [Niksa Energy Associates LLC, Belmont, CA (United States); Fujiwara, Naoki [Idemitsu Kosan Co., Ltd, Chiba (Japan). Coal and Environment Research Lab.

2013-07-01

The database on the devolatilization of Chinese coals in the English literature represents coals from all ranks and the major Chinese mines. It was mostly acquired with TGAs. There are sufficient datasets from devices that imposed rapid heating rates to bracket combustor behavior. The domains of heating rate, temperature, pressure, and particle size are either directly relevant to combustion conditions, or close enough to manage with modest extrapolations. Whereas the data on ultimate total yields is sufficient to validate a model for any coal type, more detailed product distributions and char compositions would be desirable. Based on the accurate interpretation of this database, there are few unresolved issues surrounding the applicability of FLASHCHAIN {sup registered} for combustion applications in China. The sub-database on devolatilization under rapid heating conditions represents 34 samples. The predicted yields were within the measurement uncertainties of 4 daf wt. % for 29 of these coals. Among the five ultimate yields that were not accurately predicted, three had measured values less than the proximate volatile matter (PVM), despite the rapid heating rates in the tests. Similarly, the sub-database on devolatilization under slow heating conditions characterizes ultimate devolatilization yields of 30 samples. The predicted yields were within the measurement uncertainties for 22 of these coals. Among the eight that were not accurately predicted, three had measured values that were much lower than the PVM (which is a problem even after accounting for the slow heating rates in the tests) and three were in studies that did not report ultimate analyses for the coals tested. Unfortunately, the database on the combustion behavior of the chars from Chinese coals is insufficient to specify char oxidation kinetics.

Potential of using stable nitrogen isotope ratio measurements to resolve fuel and thermal NOx in coal combustion

Energy Technology Data Exchange (ETDEWEB)

Chenggong Sun; Janos Lakatos; Colin E. Snape; Tony Fallick [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering (SChEME)

2003-07-01

In order to examine the potential of applying isotopic analysis to apportion NOx formation from different mechanisms, stable nitrogen isotope ratio measurements have been conducted on a number of thermal/prompt (diesel) and actual (coal) PF NO samples generated from a 1MW test facility at Powergen (UK), together with measurements on a range of pyrolysis and combustion chars obtained from a drop-tube reactor. A highly effective nitrogen-free sorbent, derived from white sugar with Mn as promoter, has been developed using an innovative procedure. This adsorbent has facilitated, for the first time, the determination of {delta}{sup 15}N values without background corrections. The isotopic data indicate that the thermal/prompt NOx collected during start-up with diesel as fuel has a {delta}{sup 15}N of close to 6.5(per thousand) compared to +15(per thousand) for the actual PF sample analysed. Thus, differences of up to ca. 20(per thousand) have been found to exist between thermal and PF fuel (char) NOx isotopic values. This augurs very well for the further development of the approach in order to help quantify the extent of thermal/prompt NOx formation in PF combustion. Measurements on chars have indicated that the extent of isotopic fractionation that occurs between coal-N and NOx from char is related to the reactivity of coals. Further, it would appear that much of the isotopic fractionation that occurs between coal nitrogen and fuel NO arises in the formation of char, although further fractionation can be inferred to occur during char combustion. In contrast, a lesser degree of isotopic fractionation is associated with the formation of thermal NO (ca. 6(per thousand)), atmospheric nitrogen having a value of 0(per thousand). 4 refs., 6 tabs.

A Mechanistic Investigation of Nitrogen Evolution and Corrosion with Oxy-Combustion

Energy Technology Data Exchange (ETDEWEB)

Dale Tree; Andrew Mackrory; Thomas Fletcher

2008-12-31

A premixed, staged, down-fired, pulverized coal reactor and a flat flame burner were used to study the evolution of nitrogen in coal contrasting differences in air and oxy-combustion. In the premixed reactor, the oxidizer was staged to produce a fuel rich zone followed by a burnout zone. The initial nominal fuel rich zone stoichiometric ratio (S.R.) of 0.85 selected produced higher NO reductions in the fuel rich region under oxy-combustion conditions. Air was found to be capable of similar NO reductions when the fuel rich zone was at a much lower S.R. of 0.65. At a S.R. of 0.85, oxy-combustion was measured to have higher CO, unburned hydrocarbons, HCN and NH{sub 3} in the fuel rich region than air at the same S.R. There was no measured difference in the initial formation of NO. The data suggest devolatilization and initial NO formation is similar for the two oxidizers when flame temperatures are the same, but the higher CO{sub 2} leads to higher concentrations of CO and nitrogen reducing intermediates at a given equivalence ratio which increases the ability of the gas phase to reduce NO. These results are supported by flat flame burner experiments which show devolatilization of nitrogen from the coal and char to be similar for air and oxy-flame conditions at a given temperature. A model of premixed combustion containing devolatilization, char oxidation and detailed kinetics captures most of the trends seen in the data. The model suggests CO is high in oxy-combustion because of dissociation of CO{sub 2}. The model also predicts a fraction (up to 20%, dependent on S.R.) of NO in air combustion can be formed via thermal processes with the source being nitrogen from the air while in oxy-combustion equilibrium drives a reduction in NO of similar magnitude. The data confirm oxy-combustion is a superior oxidizer to air for NO control because NO reduction can be achieved at higher S.R. producing better char burnout in addition to NO from recirculated flue gas being reduced

Microanalysis of vitrous char and associated polymers: reference and ancient assemblages

Science.gov (United States)

Allue, E.; Bonnamy, S.; Courty, M. M.; Gispert I Guirado, F.

2012-12-01

Formation of vitrous char that occur in ancient charcoal assemblages have remained unsolved. Laboratory experiments refuted vitrification to resulting from high temperature charring of green or resinous wood. This puzzling problem has been refreshed by showing the association to the charcoal and vitrous char of plastics that were originally supposed to only be produced by petroleum industry. Extraction of similar polymers within geological glassy products from cosmic airbursts has suggested impact processes to possibly forming the carbonaceous polymorphs. The pulverisation at the ground in the Angles village (French Eastern Pyrenees) following the 2011 August 2nd high altitude meteor explosion of exotic debris with vitrous char and polymers, just alike the puzzling ones of the geological and archaeological records, has provided potential reference materials. We present here their microanalysis by Environmental SEM with EDS, Raman micro-spectrometry and FTIR, XRD, TEM, ICP-MS and isotope analyses. The characterization helps elucidating how the carbonaceous polymorphs formed by transient heating and transient high pressure of atmospheric aerosols. Under TEM the vesicular, dense, vitrous char show high structural organization with a dense pattern of nano-sized graphitized domains, metals and mineral inclusions. The coupled Raman-ESEM has allowed identifying a complex pattern at micro scales of ordered "D" peak at 1320-1350 cm-1 and the graphitic, ordered peak at 1576-1590 cm-1, in association to amorphous and poorly graphitic ordered carbon. The later occurs within plant cells that have been extracted from the dense vitrous char by performing controlled combustion under nitrogen up to 1000°C. In contrast, the brittle, vesicular vitrous char and the polymers encountered at the rear of the pulverised airburst debris reveal to be formed of agglutinated micro spherules of amorphous carbon with rare crystallized carbon nano-domains and scattered mineral inclusions. They

The importance of fuel properties in the formation of nitrogen oxides and in combustion

International Nuclear Information System (INIS)

Huotari, J.; Aho, M.; Haemaelaeinen, J.; Huotari, J.; Saastamoinen, J.; Rantanen, J.

1995-01-01

The goal of this work is to find new information about the effects of pressure, temperature and fuel properties (Fuel-O/Fuel-N) on the formation of nitrogen oxides through the most important intermediates (NH 3 and HCN). In addition, a single particle model for the simultaneous pyrolysis and char combustion will be improved to be used for calculating combustion under pressure. Experimental work is done with an electrically heated pressurized entrained flow reactor (PEFR) which is equipped with modern analytics (as FT-IR for the analysis of N 2 O, NO and NO 2 and FT-IR pyrometry for the measurement of particle temperatures). The experimental work is carried out in several stages: (a) Study of the formation of HCN and NH 3 during pressurized pyrolysis (b) Oxidation of HCN and NH 3 to nitrogen oxides in pressurized combustion (c) Reduction of NO by NH 3 under pressure (thermax denox) Task a is performed with fuels of various O/N ratio. Task b is performed with pure HCN and NH 3 and with more complicated gas mixtures including HCN and NH 3 . A large part of these results are utilized in kinetic modelling in Aabo Akademi University, Finland in project LIEKKI 2-201. Two kinds of modelling work is performed in VTT in this project (a) Simultaneous modelling of the composition of solid and gaseous phases in the pyrolysis and combustion of a small fuel particle (multiphase modelling) (b) Modelling of pyrolysis and combustion of a single fuel particle under pressurized conditions (single particle modelling). The results can be used in planning of pressurized combustors and in minimizing the emissions of nitrogen oxides. (author)

The importance of fuel properties in the formation of nitrogen oxides and in combustion

International Nuclear Information System (INIS)

Aho, M.; Haemaelaeinen, J.; Rantanen, J.; Saastamoinen, J.

1996-01-01

Reactions of fuel nitrogen during pyrolysis and combustion of pulverized hvb coal, two peats and fir bark, thermal DeNOx-process and formation of N 2 0 from char were studied experimentally in a pressurized entrained flow reactor. Mass loss of fuel, release of C,N,H and 0, and formation of NH 3 and HCN were measured during pyrolysis (in N 2 containing O 2 vol ). Mass loss, and formation of NO, N 2 O and NO 2 through HCN and NH 3 were measured during combustion at 5-4 vol% O 2 . Thermal DeNOx process was studied at 2 and 15 bar at T= 700-950 deg C. Formation of N 2 O from peat and its char was studied in a modified thermobalance. The rate of pyrolysis of high-volatile fuels (fir bark and peat) increased with pressure. A reverse trend was found with Polish hvb coal. The HCN/NH 3 ratio in the flame was dependent on the fuel-O/fuel-N ratio and independent of pressure. Pressure did, however, increase the N 2 O/NO ratio, because the concentrations of the key radicals in NO formation are decreased by pressure. With peats, the formation of N 2 O increased slightly with pressure. The emissions of N 2 O, however, doubled with wood bark when the pressure increased from 0.2 MPa to 0.8 MPa. Formation of NO 2 increased clearly with pressure, and was fuel-dependent. One peat sample produced three times as much NO 2 as the other under identical conditions. Pressure seemed to effect on Thermal DeNOx-process by lowering the effective temperature. Experiments with entrained flow of fuel and its char in project Liekki2-301, and experiments with single char and fuel particles in this project suggested that volatile nitrogen forms much more N 2 O than char-N. Bed effects can change this situation in a real fluidized bed combustion process. (author)

Interactive wood combustion for botanical tree models

KAUST Repository

Pirk, Sören

2017-11-22

We present a novel method for the combustion of botanical tree models. Tree models are represented as connected particles for the branching structure and a polygonal surface mesh for the combustion. Each particle stores biological and physical attributes that drive the kinetic behavior of a plant and the exothermic reaction of the combustion. Coupled with realistic physics for rods, the particles enable dynamic branch motions. We model material properties, such as moisture and charring behavior, and associate them with individual particles. The combustion is efficiently processed in the surface domain of the tree model on a polygonal mesh. A user can dynamically interact with the model by initiating fires and by inducing stress on branches. The flames realistically propagate through the tree model by consuming the available resources. Our method runs at interactive rates and supports multiple tree instances in parallel. We demonstrate the effectiveness of our approach through numerous examples and evaluate its plausibility against the combustion of real wood samples.

Combustion Behaviour of Pulverised Wood - Numerical and Experimental Studies. Part 1 Numerical Study

Energy Technology Data Exchange (ETDEWEB)

Elfasakhany, A.; Xue-Song Bai [Lund Inst. of Tech. (Sweden). Dept. of Heat and Power Engineering

2002-12-01

This report describes a theoretical/numerical investigation of the particle motion and the particle drying, pyrolysis, oxidation of volatile and char in a pulverised biofuel (wood) flame. This work, along with the experimental measurement of a pulverised wood flame in a vertical furnace at TPS, is supported by the Swedish Energy Agency, STEM. The fundamental combustion process of a pulverised wood flame with determined size distribution and anisotropy character is studied. Comprehensive submodels are studied and some models not available in the literature are developed. The submodels are integrated to a CFD code, previously developed at LTH. The numerical code is used to simulate the experimental flame carried out at TPS (as sub-task 2 within the project). The sub-models describe the drying, devolatilization, char formation of wood particles, and the oxidation reaction of char and the gas phase volatile. At the present stage, the attention is focused on the understanding and modelling of non-spherical particle dynamics and the drying, pyrolysis, and oxidation of volatile and char. Validation of the sub-models against the experimental data is presented and discussed in this study. The influence of different factors on the pulverised wood flame in the TPS vertical furnace is investigated. This includes shape of the particles, the effect of volatile release, as well as the orientation of the particles on the motion of the particles. The effect of particle size on the flame structure (distribution of species and temperature along the axis of the furnace) is also studied. The numerical simulation is in close agreement with the TPS experimental data in the concentrations of species O{sub 2}, CO{sub 2} as well as temperature. Some discrepancy between the model simulations and measurements is observed, which suggests that further improvement in our understanding and modeling the pulverised wood flame is needed.

Degradation of p-Nitrophenol by Lignin and Cellulose Chars: H2O2-Mediated Reaction and Direct Reaction with the Char.

Science.gov (United States)

Yang, Jing; Pignatello, Joseph J; Pan, Bo; Xing, Baoshan

2017-08-15

Chars and other black carbons are reactive toward certain compounds. Such reactivity has been attributed to reduction of O 2 by persistent free radicals in the solid to H 2 O 2 , which then back-reacts with the solid to generate reactive oxygen species (ROS; especially HO • ). We studied the decomposition of p-nitrophenol (PNP) by pure lignin and cellulose chars aged in moist air or a vacuum at room temperature for up to a month. In air, the chars chemisorbed oxygen, a portion of which was liberated as H 2 O 2 when the char was submerged in water. The evolved H 2 O 2 was simultaneously decomposed by the char. PNP reacted predominantly in the sorbed state and only reduction products (phenol, catechol) were identified. Aging the char in air sharply (within hours) reduced H 2 O 2 -producing capacity and free radical concentration, but more gradually reduced PNP decay rate over the month-long period. PNP decay was only modestly suppressed (12-30%) by H 2 O 2 removal (catalase), and had little effect on the free radical signal (reactive sites. Lignin char was generally more reactive than cellulose char. The Fe impurity in lignin played no role. The results are relevant to the fate of pollutants in black carbon-rich environments and the use of carbons in remediation.

Gasification of biomass chars in steam-nitrogen mixture

International Nuclear Information System (INIS)

Haykiri-Acma, H.; Yaman, S.; Kucukbayrak, S.

2006-01-01

Some agricultural and waste biomass samples such as sunflower shell, pinecone, rapeseed, cotton refuse and olive refuse were first pyrolyzed in nitrogen, and then, their chars were gasified in a gas mixture of steam and nitrogen. Experiments were performed using the thermogravimetric analysis technique. Pyrolysis of the biomass samples was performed at a heating rate of 20 K/min from ambient to 1273 K in a dynamic nitrogen atmosphere of 40 cm 3 min -1 . The obtained chars were cooled to ambient temperature and then gasified up to 1273 K in a dynamic atmosphere of 40 cm 3 min -1 of a mixture of steam and nitrogen. Derivative thermogravimetric analysis profiles from gasification of the chars were derived, and the mass losses from the chars were interpreted in terms of temperature. It was concluded that gasification characteristics of biomass chars were fairly dependent on the biomass properties such as ash and fixed carbon contents and the constituents present in the ash. Different mechanisms in the three temperature intervals, namely water desorption at lower temperatures, decomposition of hydroxide minerals to oxide minerals and formation of carbon monoxide at medium temperatures and production of hydrogen at high temperatures govern the behavior of the char during the gasification process. The chars from pinecone and sunflower shell could be easily gasified under the mentioned conditions. In order to further raise the conversion yields, long hold times should be applied at high temperatures. However, the chars from rapeseed and olive refuse were not gasified satisfactorily. Low ash content and high fixed carbon content biomass materials are recommended for use in gasification processes when char from pyrolysis at elevated temperatures is used as a feedstock

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...

Dwarf char, a new form of chars (the genus Salvelinus) in Lake Kronotskoe

Science.gov (United States)

Pavlov, S.D.; Pivovarov, E.A.; Ostberg, C.O.

2012-01-01

Lake Kronotskoe is situated in the Kronotskii State Nature Reserve and is a unique natural heritage of Kamchatka. The lake–river system of the reserve includes numerous springs and small streams and three large inflowing rivers, Listvennichnaya, Unana, and Uzon, which form the main bays of Lake Kronotskoe; one river (Kronotskaya) flows from the lake. This river is characterized by several rapids, which are assumed to be unsurmountable barriers for fish migration. The ichthyofauna of the lake has been isolated for a long time, and some endemic fishes appeared, including char of the genus Salvelinus and the residential form of red salmon Oncorhynchus nerka (the local name is kokanee). These species are perfect model objects to study microevolution processes. Char of Lake Kronotskoe are characterized by significant polymorphism and plasticity [1–3]; therefore, they are extremely valuable for studying the processes of speciation and form development. That is why the populations of char in Lake Kronotskoe are unique and attract special attention of researchers. 

Flame retardancy and thermal behavior of intumescent flame-retardant EVA composites with an efficient triazine-based charring agent

Science.gov (United States)

Xu, Bo; Ma, Wen; Wu, Xiao; Qian, Lijun; Jiang, Shan

2018-04-01

Intumescent flame retardant (IFR) EVA composites were prepared based on a hyperbranched triazine charring-foaming agent (HTCFA) and ammonium polyphosphate (APP). The synergistic effect of HTCFA and APP on the flame retardancy and thermal behavior of the composites were investigated through flammability tests, cone calorimeter measurements, thermogravimetric analysis (TGA) including evolved gas analysis (TG-IR) and residue analysis (Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS), x-ray Photoelectron Spectroscopy (XPS) and scanning electron microscopy (SEM)). The flammability test results showed HTCFA/APP (1/3) system presented the best synergistic effect in flame-retardant EVA composites with the highest LOI value and UL-94 V-0 rating. As for cone calorimeter results, IFR changed the combustion behavior of EVA and resulted in remarkable decrease of flammability and smoke product. TGA results showed the synergistic effect between APP and HTCFA could strengthen the char-forming ability of composites. TG-IR results indicated the melt viscosities and gas release with increasing temperature were well-correlated for EVA/IFR composite. The residue analysis results from SEM, LRS, FT-IR and XPS revealed IFR promoted forming more compact graphitic char layer, connected by rich P–O–C and P–N structures.

The Effect of Polymer Char on Nitridation Kinetics of Silicon

Science.gov (United States)

Chan, Rickmond C.; Bhatt, Ramakrishna T.

1994-01-01

Effects of polymer char on nitridation kinetics of attrition milled silicon powder have been investigated from 1200 to 1350 C. Results indicate that at and above 1250 C, the silicon compacts containing 3.5 wt percent polymer char were fully converted to Si3N4 after 24 hr exposure in nitrogen. In contrast, the silicon compacts without polymer char could not be fully converted to Si3N4 at 1350 C under similar exposure conditions. At 1250 and 1350 C, the silicon compacts with polymer char showed faster nitridation kinetics than those without the polymer char. As the polymer char content is increased, the amount of SiC in the nitrided material is also increased. By adding small amounts (approx. 2.5 wt percent) of NiO, the silicon compacts containing polymer char can be completely nitrided at 1200 C. The probable mechanism for the accelerated nitridation of silicon containing polymer char is discussed.

The catalytic cracking mechanism of lignite pyrolysis char on tar

International Nuclear Information System (INIS)

Lei, Z.; Huibin, H.; Xiangling, S.; Zhenhua, M.; Lei, Z.

2017-01-01

The influence of different pyrolysis conditions for tar catalytic cracking will be analyzed according to the lignite pyrolysis char as catalyst on pyrolytic tar in this paper. The pyrolysis char what is the by-product of the cracking of coal has an abundant of pore structure and it has good catalytic activity. On this basis, making the modified catalyst when the pyrolysis char is activation and loads Fe by impregnation method. The cracking mechanism of lignite pyrolytic tar is explored by applying gas chromatograph to analyze splitting products of tar. The experimental results showed that: (1) The effect of tar cracking as the pyrolysis temperature, the heating rate, the volatilization of pyrolysis char and particle size increasing is better and better. The effect of the catalytic and cracking of lignite pyrolysis char in tar is best when the heating rate, the pyrolysis temperature, the volatiles of pyrolysis char, particle size is in specific conditions.(2) The activation of pyrolysis char can improve the catalytic effect of pyrolysis char on the tar cracking. But it reduces the effect of the tar cracking when the pyrolysis char is activation loading Fe. (author)

Reactivity and NO emissions of coal blends during combustion

Energy Technology Data Exchange (ETDEWEB)

B. Arias; R.I. Backreedy; A. Arenillas; J.M. Jones; F. Rubiera; M. Pourkashanian; A. Williams; J.J. Pis [Instituto Nacional del Carbon, CSIC, Oviedo (Spain)

2003-07-01

This work is focussed on burnout and NO emissions during coal blend combustion. Two different approaches were used. In a first step, experimental work was carried out in a laminar entrained flow reactor (EFR) and then computational techniques were applied to improve the burnout prediction of coals and blend during the experiments. A preliminary study on the combustibility of the samples was made using a thermogravimetric analyser. An entrained flow reactor was employed to study the behaviour of coals and blends at high heating rate and short residence times. Burnout and NO emissions were measured during these experiments. Two methods were used to modelling the combustion in the entrained flow reactor: a commercial CFD code and an advanced char burnout model. Experiments done in the EFR showed that burnout and NO emissions of some blends can be predicted from the weighted average of the values of individual coals, especially when blended coals have the same rank. When a blend is made with coals of different rank, some deviations were observed with respect to the averaged values in burnout and especially in NOx emissions. Burnouts predicted with a commercial CFD code were higher than the experimental values. The use of an advanced char burnout model improved greatly the results, showing the advantages of coupling these two mathematical techniques. 9 refs., 7 figs., 2 tabs.

Advanced Diagnostics in Oxy-Fuel Combustion Processes

DEFF Research Database (Denmark)

Brix, Jacob; Toftegaard, Maja Bøg; Clausen, Sønnik

This report sums up the findings in PSO-project 010069, “Advanced Diagnostics in Oxy- Fuel Combustion Processes”. Three areas of optic diagnostics are covered in this work: - FTIR measurements in a 30 kW swirl burner. - IR measurements in a 30 kW swirl burner. - IR measurements in a laboratory...... technique was an invaluable tool in the discussion of data obtained by gas analysis, and it allowed for estimation of combustion times in O2/CO2 where the high CO2 concentration prevents the use of the carbon mass balance for that purpose. During the project the data have been presented at a conference......, formed the basis of a publication and it is part of two PhD dissertations. The name of the conference the journal and the dissertations are listed below. - Joint Meeting of the Scandinavian-Nordic and French Sections of the Combustion Institute, Combustion of Char Particles under Oxy-Fuel Conditions...

A first step towards identification of tannin-derived black carbon: Conventional pyrolysis (Py–GC–MS) and thermally assisted hydrolysis and methylation (THM–GC–MS) of charred condensed tannins

NARCIS (Netherlands)

Kaal, J.; Nierop, K.G.J.; Kraal, P.; Preston, C.M.

2012-01-01

Tannins account for a significant proportion of plant biomass and are likely to contribute to the residues formed by incomplete biomass combustion (black carbon, BC). Nonetheless, the molecular properties of thermally modified tannins have not been investigated in laboratory charring experiments. We

Combustion characteristics of intensively cleaned coal fractions. Effect of mineral matter

Energy Technology Data Exchange (ETDEWEB)

Rubiera, F.; Arenillas, A.; Fuente, E.; Pis, J.J. [Inst. Nacional de Carbon, Oviedo (Spain); Ivatt, S. [ETSU, Harwell, Didcot (United Kingdom)

1997-12-31

The purpose of this work has been to assess the effect that intensive coal cleaning exerts on the combustion behaviour of different density-separated coal fractions. Samples with ash contents varying from 39% for the raw coal, to 2% for the cleanest fraction were obtained after density separation. Temperature-programmed combustion and isothermal gasification in air were used to measure the reactivities of the parent coal and the cleaned fractions. Coal and char reactivities increased with increasing ash content of the samples. Thermal analysis-mass spectrometry of the low-temperature ashes was also carried out in order to study the reactions of coal minerals under combustion conditions. (orig.)

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)

Modification of combustion behaviour and NO emissions by coal blending

Energy Technology Data Exchange (ETDEWEB)

Rubiera, Fernando; Arenillas, Ana; Arias, Borja; Pis, Jose J. [Department of Energy and Environment, Instituto Nacional del Carbon, CSIC, Apartado 73, 33080 Oviedo (Spain)

2002-06-20

Combustion profiles determined by TGA and experiments in a laminar entrained flow reactor (EFR) were used in this work to assess the relative combustion reactivities of different rank coals and their binary coal blends. The combustion behaviour of coal blends in TGA was greatly influenced by coal rank and the proportion of each component in the blend. Higher volatile coals exerted more influence in the low-temperature region and less reactive coals in the char combustion zone. The results in the EFR indicated that coal blends burnout and NO emissions show additivity in the case of similar nature coals. When one of the components was a high-rank coal, the burnout of the blend exhibited, in some cases, positive synergistic effects, while a clear deviation from linearity was found in NO emissions.

A model of the enhancement of coal combustion using high intensity acoustic fields

International Nuclear Information System (INIS)

Yavuzkurt, S.; Ha, M.Y.; Koopmann, G.H.; Scaroni, A.

1989-01-01

In this paper a model for the enhancement of coal combustion in the presence of high intensity acoustics is developed. A high intensity acoustic field induces an oscillating velocity over pulverized coal particles otherwise entrained in the main gas stream, resulting in increased heat and mass transfer. The augmented heat and mass transfer coefficients, expressed as space- and time-averaged Nusselt and Sherwood numbers for the oscillating flow, were implemented in an existing computer code (PCGC-2) capable of predicting various aspects of pulverized coal combustion and gasification. Increases in the Nusselt and Sherwood numbers of about 45, 60 and 82.5% at sound pressure levels of 160, 165, and 170 dB for 100 μm coal particles were obtained due to increases in the acoustic slop velocity associated with the increased sound pressure levels. The main effect of the acoustic field was observed during the char combustion phase in a diffusionally controlled situation. A decrease in the char burnout length (time) of 15.7% at 160 dB and 30.2% at 170 dB was obtained compared to the case with no sound for the 100 μm coal particles

Two-stage combustion, a new concept in reducing alkali related operational problem; Tvaastegsfoerbraenning, ett nytt koncept att minska alkalirelaterad driftproblematik

Energy Technology Data Exchange (ETDEWEB)

Hjoernhede, Anders; Hermansson, Sven; Seemann, Martin; Alamia, Alberto; Larsson, Anton; Davidsson, Kent; Niklasson, Fredrik; Atongka Tchoffor, Placid; Jones, Frida

2012-07-01

A possible way to reduce alkali related problems during thermal conversion of fuels into heat and power is to thermally split the fuel into a relatively alkali-lean gas stream and a relatively alkali-rich char stream. The alkali-lean gas stream could then be combusted and used for high-temperature purpose, e.g. superheating of steam. The char residue could be combusted for heating of e.g. steam tubes at inferior temperatures. The purpose of this project has been to study and demonstrate such two-stage combustion, with separation of the early devolatilization from alkali-rich fuels for steam superheating. Within the project, it has been investigated if this type of thermal conversion is thermo-economically feasible. Furthermore, it has been investigated in laboratory and pilot scale trials, which kinds of fuels, temperature levels and fuel residence times that are required to achieve a flue gas with significantly lower concentrations of alkaloids, compared to single-stage conversion. The results from the thermo-economical simulations show that it is possible to arrange the heat exchanger surfaces in a power plant for thermal two-stage conversion. Compared to traditional one-stage combustion, the electricity efficiency could be increased from 35 % to more than 38 %. However, the results from combustion, gasification and pyrolysis in lab, together with gasification trials in the Chalmers pilot plant, show that the investigated woody fuels (bark and wood pellets) do not seem to be feasible for two-stage conversion. These fuels emit alkaloids exclusively in conjunction with the devolatilization in opposite to the desired effect. On the other hand, straw is a potential fuel candidate for two-stage conversion, since straw emits alkaloids during both devolatilization and char conversion. Furthermore, the results show that increased temperature generally causes increased alkali release. From the results it is suggested that the propensity of a fuel to release alkali during

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.

A kinetic study on the catalysis of KCl, K2SO4, and K2CO3 during oxy-biomass combustion.

Science.gov (United States)

Deng, Shuanghui; Wang, Xuebin; Zhang, Jiaye; Liu, Zihan; Mikulčić, Hrvoje; Vujanović, Milan; Tan, Houzhang; Duić, Neven

2018-07-15

Biomass combustion under the oxy-fuel conditions (Oxy-biomass combustion) is one of the approaches achieving negative CO 2 emissions. KCl, K 2 CO 3 and K 2 SO 4 , as the major potassium species in biomass ash, can catalytically affect biomass combustion. In this paper, the catalysis of the representative potassium salts on oxy-biomass combustion was studied using a thermogravimetric analyzer (TGA). Effects of potassium salt types (KCl, K 2 CO 3 and K 2 SO 4 ), loading concentrations (0, 1, 3, 5, 8 wt%), replacing N 2 by CO 2 , and O 2 concentrations (5, 20, 30 vol%) on the catalysis degree were discussed. The comparison between TG-DTG curves of biomass combustion before and after water washing in both the 20%O 2 /80%N 2 and 20%O 2 /80%CO 2 atmospheres indicates that the water-soluble minerals in biomass play a role in promoting the devolatilization and accelerating the char-oxidation; and the replacement of N 2 by CO 2 inhibits the devolatilization and char-oxidation processes during oxy-biomass combustion. In the devolatilization stage, the catalysis degree of potassium monotonously increases with the increase of potassium salt loaded concentration. The catalysis degree order of the studied potassium salts is K 2 CO 3  > KCl > K 2 SO 4 . In the char-oxidation stage, with the increase of loading concentration the three kinds of potassium salts present inconsistent change tendencies of the catalysis degree. In the studied loading concentrations from 0 to 8 wt%, there is an optimal loading concentration for KCl and K 2 CO 3 , at 3 and 5 wt%, respectively; while for K 2 SO 4 , the catalysis degree on char-oxidation monotonically increases with the loading potassium concentration. For most studied conditions, regardless of the potassium salt types or the loading concentrations or the combustion stages, the catalysis degree in the O 2 /CO 2 atmosphere is stronger than that in the O 2 /N 2 atmosphere. The catalysis degree is also affected by the O 2

Thermal analysis and kinetics of coal during oxy-fuel combustion

Science.gov (United States)

Kosowska-Golachowska, Monika

2017-08-01

The pyrolysis and oxy-fuel combustion characteristics of Polish bituminous coal were studied using non-isothermal thermogravimetric analysis. Pyrolysis tests showed that the mass loss profiles were almost similar up to 870°C in both N2 and CO2 atmospheres, while further mass loss occurred in CO2 atmosphere at higher temperatures due to char-CO2 gasification. Replacement of N2 in the combustion environment by CO2 delayed the combustion of bituminous coal. At elevated oxygen levels, TG/DTG profiles shifted through lower temperature zone, ignition and burnout temperatures decreased and mass loss rate significantly increased and complete combustion was achieved at lower temperatures and shorter times. Kinetic analysis for the tested coal was performed using Kissinger-Akahira-Sunose (KAS) method. The activation energies of bituminous coal combustion at the similar oxygen content in oxy-fuel with that of air were higher than that in air atmosphere. The results indicated that, with O2 concentration increasing, the activation energies decreased.

Thermovolumetric investigations of steam gasification of coals and their chars

Directory of Open Access Journals (Sweden)

Porada Stanisław

2017-01-01

Full Text Available The process of steam gasification of three coals of various rank and three chars obtained from these coals by the ex-situ method at 900 °C was compared. In the coal gasification process, the pyrolysis stage plays a very important part, which is connected with its direct impact on the kinetics of gasification of the resulting char. What is more, taking into consideration the impact of pyrolysis conditions on char properties, it should be anticipated that the gasification kinetics of coal and char, formed from it by the ex situ method, will be different. In order to examine and compare the process of gasification of coals and chars, an isothermal thermovolumetric method, designed by the authors, was applied. For all the examined samples the measurements were performed at three temperatures, i.e. 850, 900, and 950 °C, and at the pressure of 0.1 MPa. An evaluation of the impact of raw material on the steam gasification of the examined samples was made. The carbon conversion degree and the kinetic parameters of CO and H2 formation reaction were calculated. It was observed that the course of gasification is different for coals and chars obtained from them and it can be concluded that coals are more reactive than chars. Values of kinetic parameters of carbon monoxide and hydrogen formation calculated for coals and corresponding chars are also different. Due to the observed differences the process of gasification of coals and of chars with steam should not be equated.

Modelling NO[sub x] formation in coal particle combustion at high temperature: an investigation of the devolatilisation kinetic factors

Energy Technology Data Exchange (ETDEWEB)

Jones, J.M.; Patterson, P.M.; Pourkashanian, M.; Williams, A.; Arenillas, A.; Rubiera, F.; Pis, J.J. (University of Leeds, Leeds (United Kingdom). Dept. of Fuel and Energy)

1999-08-01

Coal combustion computational fluid dynamic (CFD) models are a powerful predictive tool in combustion research. In existing coal combustion CFD models, the process is described by three kinetic rates: coal devolatilizaton, volatile combustion and char combustion. A general, representative devolatilisation rate for coal is a matter of some contention, and measured rates depend upon the type of experimental system employed in their determination. Thus the reported rates vary considerably, causing difficulties in the choice of rate expression for CFD modelling applications. In this investigation, a laminar flow CFD model of a drop-tube furnace was used to assess the influence of global devolatilisation rates on overall combustion behaviour, and in particular, NOx emissions. The rates chosen include some of the common expressions employed by researchers in the field. Analysis, and comparison of the modelling results with those of the experimental indicated that a single-step devolatilisation rate can give satisfactory profiles. This rate can be calculated from the tar release rate using a network model such as FG-DVC (functional group, depolymerisation, vaporisation and cross-linking) together with the nitrogen partitioning between gas and char during pyrolysis. The use of these single-step models result in good predictions of NOx, and the inclusion of soot/NOx interactions can improve the mode significantly to give an excellent agreement with experimental results. 2 refs., 4 figs., 3 tabs.

Characterising the combustion behaviour of New Zealand coals by thermogravimetry

Energy Technology Data Exchange (ETDEWEB)

Benfell, K.E.; Beamish, B.B.; Rodgers, K.A. [University of Auckland, Auckland (New Zealand). Dept. of Geology

1995-12-31

Thirty-three New Zealand coals were subjected to thermogravimetric analysis (TG) and derivative thermogravimetric analysis (DTG) to evaluate the techniques` applicability to New Zealand coals. Generally, New Zealand sub-bituminous coals have lower burnout temperatures than bituminous coals. However, local and regional differences occur, where some sub-bituminous coals show both higher and lower char burnout temperatures than may be otherwise expected from their rank and T{sub 6} values (the peak temperature where the rate of weight loss of the sample is the greatest). There is a sizeable variations in the char burnout temperature (T{sub 8}) (465 to 636{degree}C) in coals with volatile matter contents above 40%, whereas coals with lower volatile contents have T{sub 8} values around 646{degree}C. The temperature of char burnout gives a better indication of combustion efficiency than rank or volatile matter content alone. Industrial operators could use this technique to provide an indication of burnout performance before a coal is purchased, assisting evaluation of the coal`s suitability for a particular usage. 10 refs., 4 figs., 3 tabs.

Nitric oxide reduction over a synthetic coal char

Energy Technology Data Exchange (ETDEWEB)

C. Pevida; A. Arenillas; F. Rubiera; J.J. Pis [Instituto Nacional del Carbon, CSIC, Oviedo (Spain)

2003-07-01

In the present work, the mechanisms involved in the NO heterogeneous reduction have been investigated. A synthetic coal char was used as the carbon source. This synthetic coal was made from a mixture of model compounds and provides well-known functionalities, including nitrogenated ones, similar to those found in a high volatile bituminous coal. The char was obtained by pyrolysis of the synthetic coal, up to 1123 K, under helium atmosphere in a fixed bed reactor. Char texture and structure were characterised by N{sub 2} and CO{sub 2} adsorption isotherms at 77 and 273 K, respectively, X-ray diffraction, immersion calorimetry in C{sub 6}H{sub 6} and scanning electron microscopy (SEM). Temperature programmed reactions (TPR) were carried out in a thermogravimetric analyser using 400 ppm NO diluted in Ar as the reactant gas. The char was heated at 15 K min{sup -1} from room temperature to 1273 K. Gaseous products were simultaneously analysed by mass spectrometry (MS) and Fourier transform infrared spectroscopy (FTIR). The influence of nitrogen in the solid phase on the reduction mechanism was evaluated by comparing the results for chars with and without nitrogen in their composition. The results of this preliminary study showed that the presence of nitrogen in the chars composition did not favour the heterogeneous NO reduction. In addition, low temperature NO chemisorption on the carbon surface creates complexes that take an active part in the subsequent reactions with NO. 5 refs., 4 figs., 3 tabs.

Production of activated char from Illinois coal for flue gas cleanup

Science.gov (United States)

Lizzio, A.A.; DeBarr, J.A.; Kruse, C.W.

1997-01-01

Activated chars were produced from Illinois coal and tested in several flue gas cleanup applications. High-activity chars that showed excellent potential for both SO2 and NOx removal were prepared from an Illinois No. 2 bituminous coal. The SO2 (120 ??C) and NOx (25 ??C) removal performance of one char compared favorably with that of a commercial activated carbon (Calgon Centaur). The NOx removal performance of the same char at 120 ??C exceeded that of the Centaur carbon by more than 1 order of magnitude. Novel char preparation methods were developed including oxidation/thermal desorption and hydrogen treatments, which increased and preserved, respectively, the active sites for SO2 and NOx adsorption. The results of combined SO2/NOx removal tests, however, suggest that SO2 and NOx compete for similar adsorption sites and SO2 seems to be more strongly adsorbed than NO. A low-activity, low-cost char was also developed for cleanup of incinerator flue gas. A three-step method involving coal preoxidation, pyrolysis, and CO2 activation was used to produce the char from Illinois coal. Five hundred pounds of the char was tested on a slipstream of flue gas from a commercial incinerator in Germany. The char was effective in removing >97% of the dioxins and furans present in the flue gas; mercury levels were below detectable limits.

Challenges in simulation of chemical processes in combustion furnaces

Energy Technology Data Exchange (ETDEWEB)

Hupa, M.; Kilpinen, P. [Aabo Akademi, Turku (Finland)

1996-12-31

The presentation gives an introduction to some of the present issues and problems in treating the complex chemical processes in combustion. The focus is in the coupling of the hydrocarbon combustion process with nitrogen oxide formation and destruction chemistry in practical furnaces or flames. Detailed kinetic modelling based on schemes of elementary reactions are shown to be a useful novel tool for identifying and studying the key reaction paths for nitrogen oxide formation and destruction in various systems. The great importance of the interaction between turbulent mixing and combustion chemistry is demonstrated by the sensitivity of both methane oxidation chemistry and fuel nitrogen conversion chemistry to the reactor and mixing pattern chosen for the kinetic calculations. The fluidized bed combustion (FBC) nitrogen chemistry involves several important heterogeneous reactions. Particularly the char in the bed plays an essential role. Recent research has advanced rapidly and the presentation proposes an overall picture of the fuel nitrogen reaction routes in circulating FBC conditions. (author)

Challenges in simulation of chemical processes in combustion furnaces

Energy Technology Data Exchange (ETDEWEB)

Hupa, M; Kilpinen, P [Aabo Akademi, Turku (Finland)

1997-12-31

The presentation gives an introduction to some of the present issues and problems in treating the complex chemical processes in combustion. The focus is in the coupling of the hydrocarbon combustion process with nitrogen oxide formation and destruction chemistry in practical furnaces or flames. Detailed kinetic modelling based on schemes of elementary reactions are shown to be a useful novel tool for identifying and studying the key reaction paths for nitrogen oxide formation and destruction in various systems. The great importance of the interaction between turbulent mixing and combustion chemistry is demonstrated by the sensitivity of both methane oxidation chemistry and fuel nitrogen conversion chemistry to the reactor and mixing pattern chosen for the kinetic calculations. The fluidized bed combustion (FBC) nitrogen chemistry involves several important heterogeneous reactions. Particularly the char in the bed plays an essential role. Recent research has advanced rapidly and the presentation proposes an overall picture of the fuel nitrogen reaction routes in circulating FBC conditions. (author)

Thermogravimetric analysis of co-combustion between microalgae and textile dyeing sludge.

Science.gov (United States)

Peng, Xiaowei; Ma, Xiaoqian; Xu, Zhibin

2015-03-01

The synergistic interaction and kinetics of microalgae, textile dyeing sludge and their blends were investigated under combustion condition by thermogravimetric analysis. The textile dyeing sludge was blended with microalgae in the range of 10-90wt.% to investigate their co-combustion behavior. Results showed that the synergistic interaction between microalgae and textile dyeing sludge improved the char catalytic effect and alkali metals melt-induced effect on the decomposition of textile dyeing sludge residue at high temperature of 530-800°C. As the heating rate increasing, the entire combustion process was delayed but the combustion intensity was enhanced. The lowest average activation energy was obtained when the percentage of microalgae was 60%, which was 227.1kJ/mol by OFW and 227.4kJ/mol by KAS, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ultrasonically assisted extraction of calcium and ash from char

Science.gov (United States)

Mathumba, E. E.; Mbaya, R. K. K.; Kolesnikov, A.

2018-03-01

This study characterized and removed calcium and ash content from char to improve the chemical quality of char as reductant for titanium smelting application. Calcium in char can be classified in two parts: mineral matter and cationic metals associated with organic matrix. Virgin and chemically treated char was characterized by using ISO 1171, wet chemistry methods, ISO 19579, XRF, and B.E.T. methods. In this present work, demineralization of char with mild chemical leachants such as acetic acid, citric acid, gluconic acid and Ethylene Diamine Tetra Acetic acid with three different ultrasonic power input (150 W, 270 W and 300 W) and semi-dual frequency of 40 kHz tank was investigated. Actual power dissipated into the system was calculated from the calorimetric measurement. An optimum set of process parameters are identified and validated. The ultrasound technology was compared with soaking technology to determine the efficiency of ultrasound system for the removal of calcium. The removal of calcium was exponentially higher with ultrasonic treatment than without it. Results revealed that mild chemical reagents do not harm the carbon content of char. It is evident from the results that amongst the leachants used; acetic and citric acid has caused significant removal of mineral phases.

Investigation of pressurized combustion and characterization of solid fuels

Energy Technology Data Exchange (ETDEWEB)

Aho, M; Haemaelaeinen, J; Paakkinen, K [VTT Energy, Espoo (Finland); Joutsenoja, T [Tampere Univ. of Technology (Finland)

1997-10-01

The objective of the research of Technical Research Centre of Finland (VTT) was to produce results of the effects of pressure and other important parameters on the combustion of pulverized coals using both experimental and theoretical methods. The results can be utilized to model pressurized combustion and to plan pilot-scale reactors. The studied coals were Polish hvb coal, French lignite (Gardanne), German anthracite (Niederberg) and German (Goettelborn) hvb coal. In was originally planned to study also a char of one of these coals. However, anthracite was selected instead of char, because the theoretical studies predicted maximum pressure effect to be found for antracite-type coals (with low reactivity and low content of volatiles). The pulverized coal samples were combusted in an electrically heated, pressurized entrained flow reactor (PEFR), where the experimental conditions were controlled with a high precision. The studied particle size fractions were 100-125 Em and 140-180 Am for anthracite and 140-180 {mu}m for the other coals. The studied things were combustion rates and temperatures of burning particles. Two types of sets of experiments were carried out. In the first case, experimental planning was done and the results were handled with multivariable partial least squares (PLS) method. Gas temperature varied from 1073K to 1473K and pressure from 0.2 MPa to 0.8 MPa. The other variables were PO2 and PCO{sub 2}. Some of the experiments were carried out at conditions prevailing during flue gas recirculation (CO{sub 2} concentration was > 20 vol%). In the second case, oxygen concentration was kept constant ( 10 vol%) and pressure was varied from 0.2 MPa to 0.8 MPa with an interval of 0.1 MPa

Release of K, Cl, and S during Pyrolysis and Combustion of High-Chlorine Biomass

DEFF Research Database (Denmark)

Johansen, Joakim Myung; Jakobsen, Jon Geest; Frandsen, Flemming

2011-01-01

The release of critical ash-forming elements during the pyrolysis and combustion of corn stover has been investigated through controlled lab-scale experiments supported by multicomponent and multiphase thermodynamic equilibrium calculations. Fuel samples were treated under isothermal conditions...... ranging from 500 to 1150 °C, under both pyrolysis and combustion atmospheres. The volatilized material was quantified by means of mass balances based on char and ash elemental analysis, compared to a corresponding feedstock fuel analysis. Close relations between the observed K and Cl release are found...

Attrition-free pyrolysis to produce bio-oil and char.

Science.gov (United States)

Mauviel, Guillain; Guillain, Mauviel; Kies, Fairouz; Fairouz, Kies; René, Mar Sans; Mar, Sans Rene; Ferrer, Monique; Monique, Ferrer; Lédé, Jacques; Jacques, Lédé

2009-12-01

Experiments are performed on a laboratory scale setup where beech wood chips are heated by gas convection and walls radiation. This study shows that it is possible to obtain high bio-oil and char yields with relatively low external heat transfer coefficients. The main advantage of this convection/radiation heat transfer mode compared to solid-solid collisions, applied in fluidized bed or twin screw reactors, is the reduction of solid attrition (char and sand). Thus tricky gas-solid separation through hot cyclones and/or hot filters could be avoided or reduced. It should be possible to recover directly bio-oil with less char particles and char free of sand dust. These qualities would allow easier use of these bio-products in different applications.

Combustion of large solid fuels in cement rotary kilns

DEFF Research Database (Denmark)

Nielsen, Anders Rooma

(MBM), waste wood, sewage sludge, paper and plastics. The alternative fuel share of the total energy varies significantly from region to region, but the general trend is towards increased alternative fuel utilization. Solid alternative fuels typically have physical and chemical properties that differ...... from traditional solid fossil fuels. This creates a need for new combustion equipment or modification of existing kiln systems, because alternative fuels may influence process stability and product quality. Process stability is mainly influenced by exposing the raw material bed in the rotary kiln...... oxidation is a slow process which may greatly reduce the amounts of solid fuels to be utilized in the material inlet end of rotary kilns due to the limited residence time. Several parameters control the rate of char oxidation: a) bulk oxygen concentration, b) mass transfer rate of oxygen to char particles...

A study on the char burnout characteristics of coal and biomass blends

Energy Technology Data Exchange (ETDEWEB)

Behdad Moghtaderi [University of Newcastle, Callaghan, NSW (Australia). Discipline of Chemical Engineering, School of Engineering, Faculty of Engineering and Built Environment

2007-10-15

The char burnout characteristics of coal/biomass blends under conditions pertinent to pulverised fuel combustors were investigated by a combined modelling and experimental approach. Results indicate that blending of coal with biomass increases the likelihood of char extinction (i.e. extinction potential of the char particle in the blend), in turn, decreasing the char burnout level. Our modelling results attribute this to a reduction in the char particle size to levels below a critical dimension which appears to be a strong function of the fuel blending ratio (the weight percentage of biomass in the blend), fuel reactivity, char cloud shape and particle density number. It is demonstrated here that the drop in the char burnout level during co-firing can be effectively resolved when a more reactive secondary coal is added to the blend to minimise its extinction potential. 22 refs., 8 figs., 2 tabs.

Effect of burn-off on physical and chemical properties of coal char; Gas ka shinko ni tomonau sekitan char no tokusei henka

Energy Technology Data Exchange (ETDEWEB)

Yamada, T.; Tamura, K.; Hashimoto, H.; Funaki, M.; Suzuki, T. [Kitami Institute of Technology, Hokkaido (Japan)

1996-10-28

For high-efficiency coal gasification, investigations were given on effect of coal chars with different conversion rates on coal gasification reactivity. In coal gasification, reactivity of char after pyrolysis governs the efficiency. The reference char conversion in CO2 gasification of coal (weight loss) changes linearly in the initial stage of the reaction, but the reactivity declines as the end point is approached. Char surface area is as large as 400 m{sup 2}/g in the initial stage with the conversion at 20%, but it decreases in the final stage. This phenomenon relates closely with changes in pore size and crystalline structure. Change in the Raman value R which shows incompleteness of char graphite structure and amorphous carbon ratio suggests that an active portion with high reactivity is oxidized preferentially, and a portion with low reactivity remains finally. Minerals in coal are known to accelerate the gasification. However, their catalytic effect is related with chemical forms, and complex as they may change into inactive sulfides and silicates under severe reaction conditions. Change in forms of calcium compounds may also be involved in decline of the reactivity in the latter stage. 8 refs., 4 figs.

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.

Intrinsic char reactivity of plastic waste (PET) during CO2 gasification

International Nuclear Information System (INIS)

Gil, M.V.; Fermoso, J.; Pevida, C.; Pis, J.J.; Rubiera, F.

2010-01-01

Char reactivity has a strong influence on the gasification process, since char gasification is the slowest step in the process. A sample of waste PET was devolatilised in a vertical quartz reactor and the resulting char was partially gasified under a CO 2 atmosphere at 925 C in order to obtain samples with different degrees of conversion. The reactivity of the char in CO 2 was determined by isothermal thermogravimetric analysis at different temperatures in a kinetically controlled regime and its reactive behaviour was evaluated by means of the random pore model (RPM). The texture of the char was characterised by means of N 2 and CO 2 adsorption isotherms. The results did not reveal any variation in char reactivity during conversion, whereas the micropore surface area was affected during the gasification process. It was found that the intrinsic reaction rate of the char can be satisfactorily calculated by normalizing the reaction rate by the narrow micropore surface area calculated from the CO 2 adsorption isotherms. It can be concluded therefore that the surface area available for the gasification process is the area corresponding to the narrow microporosity. (author)

Study on coal char ignition by radiant heat flux.

Science.gov (United States)

Korotkikh, A. G.; Slyusarskiy, K. V.

2017-11-01

The study on coal char ignition by CO2-continuous laser was carried out. The coal char samples of T-grade bituminous coal and 2B-grade lignite were studied via CO2-laser ignition setup. Ignition delay times were determined at ambient condition in heat flux density range 90-200 W/cm2. The average ignition delay time value for lignite samples were 2 times lower while this difference is larger in high heat flux region and lower in low heat flux region. The kinetic constants for overall oxidation reaction were determined using analytic solution of simplified one-dimensional heat transfer equation with radiant heat transfer boundary condition. The activation energy for lignite char was found to be less than it is for bituminous coal char by approximately 20 %.

Mechanisms and kinetics of granulated sewage sludge combustion.

Science.gov (United States)

Kijo-Kleczkowska, Agnieszka; Środa, Katarzyna; Kosowska-Golachowska, Monika; Musiał, Tomasz; Wolski, Krzysztof

2015-12-01

This paper investigates sewage sludge disposal methods with particular emphasis on combustion as the priority disposal method. Sewage sludge incineration is an attractive option because it minimizes odour, significantly reduces the volume of the starting material and thermally destroys organic and toxic components of the off pads. Additionally, it is possible that ashes could be used. Currently, as many as 11 plants use sewage sludge as fuel in Poland; thus, this technology must be further developed in Poland while considering the benefits of co-combustion with other fuels. This paper presents the results of experimental studies aimed at determining the mechanisms (defining the fuel combustion region by studying the effects of process parameters, including the size of the fuel sample, temperature in the combustion chamber and air velocity, on combustion) and kinetics (measurement of fuel temperature and mass changes) of fuel combustion in an air stream under different thermal conditions and flow rates. The combustion of the sludge samples during air flow between temperatures of 800 and 900°C is a kinetic-diffusion process. This process determines the sample size, temperature of its environment, and air velocity. The adopted process parameters, the time and ignition temperature of the fuel by volatiles, combustion time of the volatiles, time to reach the maximum temperature of the fuel surface, maximum temperature of the fuel surface, char combustion time, and the total process time, had significant impacts. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mercury adsorption of modified mulberry twig chars in a simulated flue gas.

Science.gov (United States)

Shu, Tong; Lu, Ping; He, Nan

2013-05-01

Mulberry twig chars were prepared by pyrolysis, steam activation and impregnation with H2O2, ZnCl2 and NaCl. Textural characteristics and surface functional groups were performed using nitrogen adsorption and FTIR, respectively. Mercury adsorption of different modified MT chars was investigated in a quartz fixed-bed absorber. The results indicated that steam activation and H2O2-impregnation can improve pore structure significantly and H2O2-impregnation and chloride-impregnation promote surface functional groups. However, chloride-impregnation has adverse effect on pore structure. Mercury adsorption capacities of impregnated MT chars with 10% or 30% H2O2 are 2.02 and 1.77 times of steam activated MT char, respectively. Mercury adsorption capacity of ZnCl2-impregnated MT char increase with increasing ZnCl2 content and is better than that of NaCl-impregnated MT char at the same chloride content. The modified MT char (MT873-A-Z5) prepared by steam activation following impregnation with 5% ZnCl2 exhibits a higher mercury adsorption capacity (29.55 μg g(-1)) than any other MT chars. Copyright © 2013 Elsevier Ltd. All rights reserved.

Physico-Chemical Characterizations of Sawdust-Derived Bio char as Potential Solid Fuels

International Nuclear Information System (INIS)

Wan Azlina Wan Ab Karim Ghani

2014-01-01

Characterization Malaysian rubber-wood sawdust derived bio char (MRWSB) produced in the fixed bed pyrolysis under different temperatures (450 to 850 degree Celsius) were studied for its applicability as a solid fuel. A range of analyses were carried out, including bio char oxidation reactivity , inorganic species, oxygen and hydrogen contents in the bio chars, release of heteroatoms in bio char as the gaseous product, and bio char structural evolution during pyrolysis process. The results show that the optimum temperature for carbonization to obtain a char having moderately high yield was found as 450 degree Celsius. Thermogravimetric analyses (TG) shows that temperatures induces a progressively more ordered carbonaceous structure and leads to a significant changes in the bio char reactivity. The process is coupled with the loss of heteroatoms, released as dominantly carbon dioxide (C0 2 ) and carbon dioxide (CO). In addition, the elemental study of wood-derived bio char shows the higher carbon content but with low H/C and 0/C ratio suggested this material was dominated by highly aromatic structures and this were revealed in the Fourier transform infra-red (FTIR). More importantly, insignificant amount of inorganic species is evidenced in the samples. (author)

Influence of pyrolysis conditions on the structure and gasification reactivity of biomass chars

Energy Technology Data Exchange (ETDEWEB)

E. Cetin; B. Moghtaderi; R. Gupta; T.F. Wall [University of Newcastle, Callaghan, NSW (Australia). Discipline of Chemical Engineering, Faculty of Engineering and Built Environment, School of Engineering

2004-11-01

The physical and chemical structure as well as gasification reactivities of chars generated from several biomass species (i.e. pinus radiata, eucalyptus maculata and sugar cane bagasse) were studied to gain insight into the role of heating rate and pressure on the gasification characteristics of biomass chars. Char samples were generated in a suite of reactors including a wire mesh reactor, a tubular reactor, and a drop tube furnace. Scanning electron microscopy analysis, X-ray diffractometry, digital cinematography and surface area analysis were employed to determine the impact of operating conditions on the char structure. The global gasification reactivities of char samples were also determined for a range of pressures between 1 and 20 bar using pressurised thermogravimetric analysis technique. Char reactivities were found to increase with increasing pyrolysis heating rates and decreasing pyrolysis pressure. It was found that under high heating rates the char particles underwent plastic deformation (i.e. melted) developing a structure different to that of the virgin biomass. Pressure was also found to influence the physical and chemical structures of char particles. The difference in the gasification reactivities of biomass chars at pressure was found to correlate well with the effect of pyrolysis pressure on the graphitisation process in the biomass char structure. 29 refs., 18 figs., 2 tabs.

Properties of gasification-derived char and its utilization for catalytic tar reforming

Science.gov (United States)

Qian, Kezhen

Char is a low-value byproduct of biomass gasification and pyrolysis with many potential applications, such as soil amendment and the synthesis of activated carbon. The overall goal of the proposed research was to develop novel methods to use char derived from gasification for high-value applications in syngas conditioning. The first objective was to investigate effects of gasification condition and feedstock on properties of char derived from fluidized bed gasification. Results show that the surface areas of most of the char were 1--10 m 2/g and increased as the equivalence ratio increased. Char moisture and fixed carbon contents decreased while ash content increased as equivalence ratio increased. The next objective was to study the properties of sorghum and red cedar char derived from downdraft gasifier. Red cedar char contained more aliphatic carbon and o-alkyl carbon than sorghum char. Char derived from downdraft gasification had higher heating values and lower ash contents than char derived from fluidized bed gasification. The gasification reactivity of red cedar char was higher than that of sorghum char. Then, red cedar char based catalysts were developed with different preparation method to reform toluene and naphthalene as model tars. The catalyst prepared with nickel nitrate was found to be better than that with nickel acetate. The nickel particle size of catalyst impregnated with nickel nitrate was smaller than that of catalyst impregnated with nickel acetate. The particle size of catalyst impregnated with nickel acetate decreased by hydrazine reduction. The catalyst impregnated with nickel nitrate had the highest toluene removal efficiency, which was 70%--100% at 600--800 °C. The presence of naphthalene in tar reduced the catalyst efficiency. The toluene conversion was 36--99% and the naphthalene conversion was 37%--93% at 700--900 °C. Finally, effects of atmosphere and pressure on catalytic reforming of lignin-derived tars over the developed catalyst

Pre-treatment of biofuels for power production. Final report (1998). K. Joule 3 - OPTEB, Task: No. 19/20

Energy Technology Data Exchange (ETDEWEB)

Jensen, P.A.; Sander, B.; Dam-Johansen, K.

1999-10-01

Co-firing of straw and coal on existing pulverised coal fired power plants may cause problems with deposition, corrosion, deactivation of SCR catalysts and impedes the utilisation of the fly ash, because of the high chlorine and potassium content of straw. Experiments with co-combustion of straw and coal on boilers plants have shown, that when maximal 20% of straw on a thermal basis is applied the most serious problems is the deactivation of high dust SCR catalysts and the deterioration of fly ash quality. The objective of this work was to evaluate a large-scale pre-treatment process for straw. The process applies pyrolysis at a moderate temperature, where the alkaline is retained in the char. The char is then washed and char and pyrolysis gasses can be co-fired with coal without causing serious problems. Fundamental laboratory studies as well as technical investigations were conducted to evaluate the pre-treatment concept. The laboratory studies were mainly done to improve the understanding of potassium and chlorine release during pyrolysis and the extraction of char with water. Some work were also done with respect to particle characterisation, straw pyrolysis kinetic and straw char combustion. The technical evaluation of a plant with 20 tons/hour capacity included investigations of possible reactor technologies, waste water handling, power efficiency and investment costs. Based on the laboratory experiments a pyrolysis temperature of 500 to 600 deg. C is recommended for the pre-treatment process. A high degree of pyrolysis is obtained without a significant release of potassium to the gas, but a release of 30 to 60% of the chlorine can not be avoided. Extraction of potassium from char with water is a two-step process, where the first step is a fast dissolution of potassium salts and the second step is a slow release of potassium from the interior of the char particle. A high potassium removal during char wash could not be obtained for all types of char within

Effect of raw material particle-size distribution on combustion characteristics of stem wood pellets; Paaverkan av partikelfraktionsfoerdelningen paa utbraenningshastigheten hos traepellets vid nyttjande av olika soenderdelningsmetoder

Energy Technology Data Exchange (ETDEWEB)

Israelsson, Samuel; Henriksson, Gunnar; Boman, Christoffer; Oehman, Marcus

2007-01-15

The objective of the project was to determine the effect of raw material particle-size distribution on combustion characteristics of stem wood pellets. Several well defined pellet qualities were produced from raw materials (stem wood of pine and spruce) which had both different particle-size distributions and were produced with different milling equipments (hammer mill/refiner). The pellets were produced in a traditional (bench-scale) pellet mill and in a laboratory pellet mill/press. The combustion characteristics of the individual pellets were determined in a laboratory scale oven. Char yield, -shrinkage, -density and the micro pore volume of the produced char were also determined. Differences in total conversion times of approximately 5 % at experimental condition relevant for typical pellets equipment were determined for the different pellet qualities. The underlying reasons for the obtained differences in the combustion characteristics between the different pellet qualities are discussed in the report

Experimental comparison of biomass chars with other catalysts for tar reduction

NARCIS (Netherlands)

Abu El-Rub, Ziad; Bramer, Eduard A.; Brem, Gerrit

2008-01-01

In this paper the potential of using biomass char as a catalyst for tar reduction is discussed. Biomass char is compared with other known catalysts used for tar conversion. Model tar compounds, phenol and naphthalene, were used to test char and other catalysts. Tests were carried out in a fixed bed

Hot char-catalytic reforming of volatiles from MSW pyrolysis

International Nuclear Information System (INIS)

Wang, Na; Chen, Dezhen; Arena, Umberto; He, Pinjing

2017-01-01

Highlights: • Volatile from MSW pyrolysis is reformed with hot char from the same pyrolysis process. • The yields of syngas increase evidently with H 2 being the main contributor and the major component of the syngas. • Pyrolysis oil becomes light and its composition distribution is narrowed. • The HHV, volatile elements and alkali metals contents in the char decrease. • The emissions including SO 2 , NO, NO 2 and HCN changed after reforming process. - Abstract: Volatile products obtained from pyrolysis of municipal solid waste (MSW), including syngas and pyrolysis oil, were forced to contact the hot char from the same pyrolysis process at 500–600 °C in a fixed bed reactor to be reformed. The yields and properties of syngas, char and pyrolysis liquid were investigated; and the energy re-distribution among the products due to char reforming was quantified. The preliminary investigation at lab scale showed that hot char-catalytic reforming of the volatiles leads to an increase in the dry syngas yield from 0.25 to 0.37 N m 3 kg −1 MSW at 550 °C. Accordingly, the carbon conversion ratio into syngas increases from 29.6% to 35.0%; and the MSW chemical energy transferred into syngas increased from 41.8% to 47.4%. The yield of pyrolysis liquid products, including pyrolysis oil and water, decreased from 27.3 to 16.5 wt%, and the molecular weight of the oil becoming lighter. Approximately 60% of the water vapour contained in the volatiles converted into syngas. After reforming, the concentrations of SO 2 and HCN in the syngas decreases, while those of NO and NO 2 increase. The char concentrations of N, H, C and alkali metal species decreased and its higher heating value decreased too.

Kinetic Analysis of Char Thermal Deactivation

DEFF Research Database (Denmark)

Zolin, Alfredo; Jensen, Anker; Dam-Johansen, Kim

2001-01-01

and demineralized Dietz from USA, and two alternative fuels, Danish leached straw and petroleum coke, were used in the experiments. The coal chars from demineralized Dietz, Illinois no. 6, and Cerrejon deactivate readily, whereas petroleum coke and Blair Athol show a relative high resistance to deactivation....... Leached straw deactivates significantly, but maintains at any heat-treatment temperature a higher reactivity than the other chars. The inertinite-rich coal Blair Athol is more resistant to deactivation than two vitrinite-rich coals of the same ASTM rank, Cerrejon and Illinois no. 6. Cerrejon and Illinois...

The thermal history of char as disclosed by carbon isotope ratios

DEFF Research Database (Denmark)

Egsgaard, Helge; Ambus, Per; Ahrenfeldt, Jesper

In laboratory experiments, biomass char was produced under controlled conditions using wood chips from French pinewood. Different char qualities were obtained by pyrolysing the biomass at similar heating rates with end-temperatures ranging from 250 to 1000 o C. The char was analysed by flash...... pyrolysis and isotope ratio mass spectrometry. The results demonstrate that the temperature history of the char is reflected in the fine variation of carbon isotopes. The compound classes responsible for the variation were identified. Key words: Isotope ratio, flash pyrolysis, hot gas cleaning...

The ChemChar process for hazardous-waste treatment

International Nuclear Information System (INIS)

McGowin, A.E.

1991-01-01

The ChemChar Reverse-Burn Gasification Process has been studied for application to the thermal destruction of radioactive waste organic ion exchange resins. The resulting char was mixed with cement to form a dry, leach-resistant final disposal product. Successful regeneration of spent granular activated carbons was achieved with reverse-burn gasification. Regeneration parameters such as moisture content and supplemental fuel addition were investigated. The performance of regenerated carbon was evaluated by batch equilibrium and breakthrough assay and was comparable to that of the original. Surface areas were determined by the BET method. The fate of mercury during reverse-burn gasification was investigated. TRB Char adsorbent was used to remove mercury vapor emission from the process. The use of petroleum coke as a substrate for gasification of wastes was studied. Petroleum coke was activated by reverse-burn gasification to produce a highly porous, low surface area solid. Destruction efficiency for hexachlorobenzene on activated coke was considerably lower than on coal char, however, the addition of iron appeared to catalyze hexachlorobenzene gasification

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.

Lead sorption characteristics of various chicken bone part-derived chars.

Science.gov (United States)

Park, Jong-Hwan; Wang, Jim J; Kim, Seong-Heon; Kang, Se-Won; Cho, Ju-Sik; Delaune, Ronald D; Ok, Yong Sik; Seo, Dong-Cheol

2018-01-18

Recycling food waste for beneficial use is becoming increasingly important in resource-limited economy. In this study, waste chicken bones of different parts from restaurant industry were pyrolyzed at 600 °C and evaluated for char physicochemical properties and Pb sorption characteristics. Lead adsorption isotherms by different chicken bone chars were carried out with initial Pb concentration range of 1-1000 mg L -1 at pH 5. The Pb adsorption data were better described by the Langmuir model (R 2  = 0.9289-0.9937; ARE = 22.7-29.3%) than the Freundlich model (R 2  = 0.8684-0.9544; ARE = 35.4-72.0%). Among the chars derived from different chicken bone parts, the tibia bone char exhibited the highest maximum Pb adsorption capacity of 263 mg g -1 followed by the pelvis (222 mg g -1 ), ribs (208 mg g -1 ), clavicle (179 mg g -1 ), vertebrae (159 mg g -1 ), and humerus (135 mg g -1 ). The Pb adsorption capacities were significantly and positively correlated with the surface area, phosphate release amount, and total phosphorus content of chicken bone chars (r ≥ 0.9711). On the other hand, approximately 75-88% of the adsorbed Pb on the chicken bone chars was desorbable with 0.1 M HCl, indicating their recyclability for reuse. Results demonstrated that chicken bone char could be used as an effective adsorbent for Pb removal in wastewater.

The role of primary and secondary air on wood combustion in cookstoves

Science.gov (United States)

Kirch, Thomas; Birzer, Cristian H.; Medwell, Paul R.; Holden, Liam

2018-03-01

A two-stage solid fuel research furnace was used to examine the claim that through forced draught greater mixing and more complete combustion could be achieved. By varying the primary air (PA) and secondary air (SA) flow the influence on the combustion process was investigated. In the first part of the combustion, when the release of volatile compounds predominates, the variation of neither PA nor SA had a significant influence. In the second part when mainly char is oxidised an increase in both PA and SA lead to a rising nominal combustion efficiency (?)), with a greater impact observed with SA. Furthermore higher air flows caused the heat transfer, to a pot above the furnace, to decline. Therefore forced draught does lead to greater mixing and mitigation of emissions, but in the presented configuration a trade-off between a higher NCE and a lower heat transfer needs consideration.

Thermal analysis of charring materials based on pyrolysis interface model

Directory of Open Access Journals (Sweden)

Huang Hai-Ming

2014-01-01

Full Text Available Charring thermal protection systems have been used to protect hypersonic vehicles from high heat loads. The pyrolysis of charring materials is a complicated physical and chemical phenomenon. Based on the pyrolysis interface model, a simulating approach for charring ablation has been designed in order to obtain one dimensional transient thermal behavior of homogeneous charring materials in reentry capsules. As the numerical results indicate, the pyrolysis rate and the surface temperature under a given heat flux rise abruptly in the beginning, then reach a plateau, but the temperature at the bottom rises very slowly to prevent the structural materials from being heated seriously. Pyrolysis mechanism can play an important role in thermal protection systems subjected to serious aerodynamic heat.

Pyrolysis of superfine pulverized coal. Part 4. Evolution of functionalities in chars

International Nuclear Information System (INIS)

Liu, Jiaxun; Ma, Yang; Luo, Lei; Ma, Junfang; Zhang, Hai; Jiang, Xiumin

2017-01-01

Highlights: • A combination of XPS and NMR is adopted for analyzing char chemical structures during superfine pulverized coal pyrolysis. • The chemisorbed NO can be transformed into pyridine N with the favor of adjacent oxygenated groups in chars. • Particle size has significant influence on oxygen-containing configurations in chars. - Abstract: The properties of the coal-derived char play crucial roles in coal conversion reactions and the formation of air pollutants. The nascent char is highly reactive due to the existence of numerous free radicals, active sites, and organic functional groups on its surface. Here, we showed that a combination of nuclear magnetic resonance spectroscopy (NMR) and X-ray photoelectron spectroscopy (XPS) techniques is an effective and precise way to characterize the occurrence, distribution, and evolution of organic functionalities in coal chars. Using these methods, we explored detailed information about chemical features of superfine pulverized coal chars in different atmospheres, and we also discussed the influence of particle size on the evolutionary behavior of functionalities. Results indicate that, in both N_2 and CO_2 atmospheres, the content of C−O species increases with the reduction in char particle sizes. This increment facilitates the heterogeneous reduction of NOx on char surfaces. The chemisorbed NO is susceptible to being incorporated into chars, and being transformed into pyridine-type nitrogen with the favor of adjacent oxygen-containing groups. Moreover, the significant increment in oxygen-containing groups with the reduction of particle size is further confirmed through "1"3C NMR analysis. It was shown that there is an excellent correlation between estimates derived from XPS and NMR for oxygen configuration. The findings from this work provide some new insights into NOx reduction mechanisms and shed light on the practical application of superfine pulverized coal in the future.

FUNDAMENTAL INVESTIGATION OF FUEL TRANSFORMATIONS IN PULVERIZED COAL COMBUSTION AND GASIFICATION TECHNOLOGIES

Energy Technology Data Exchange (ETDEWEB)

Robert Hurt; Joseph Calo; Thomas H. Fletcher; Alan Sayre

2005-04-29

The goal of this project was to carry out the necessary experiments and analyses to extend current capabilities for modeling fuel transformations to the new conditions anticipated in next-generation coal-based, fuel-flexible combustion and gasification processes. This multi-organization, multi-investigator project has produced data, correlations, and submodels that extend present capabilities in pressure, temperature, and fuel type. The combined experimental and theoretical/computational results are documented in detail in Chapters 1-8 of this report, with Chapter 9 serving as a brief summary of the main conclusions. Chapters 1-3 deal with the effect of elevated pressure on devolatilization, char formation, and char properties. Chapters 4 and 5 deal with advanced combustion kinetic models needed to cover the extended ranges of pressure and temperature expected in next-generation furnaces. Chapter 6 deals with the extension of kinetic data to a variety of alternative solid fuels. Chapter 7 focuses on the kinetics of gasification (rather than combustion) at elevated pressure. Finally, Chapter 8 describes the integration, testing, and use of new fuel transformation submodels into a comprehensive CFD framework. Overall, the effects of elevated pressure, temperature, heating rate, and alternative fuel use are all complex and much more work could be further undertaken in this area. Nevertheless, the current project with its new data, correlations, and computer models provides a much improved basis for model-based design of next generation systems operating under these new conditions.

Study on pore structure properties of steam activated biomass chars

Energy Technology Data Exchange (ETDEWEB)

Shu, Tong; Lu, Fei; Wang, Qinchao; Lu, Ping [Nanjing Normal Univ. (China). School of Energy and Mechanical Engineering

2013-07-01

Wheat straw and rice husk chars were prepared in a fixed bed reactor at different pyrolysis temperatures (673, 873 and 1,073K) and different pyrolysis procedure. The steam activated chars were also prepared in a fixed bed reactor at the following conditions: activation temperature is 1,073K, the flow rate of N{sub 2} is 5L/min, and N{sub 2} and H{sub 2}O molar ratio is 1:1. The specific surface area, pore structure and micro-morphology of different kinds of prepared biomass chars were measured by NOVA1000e analysis instrument and JSM-5610LV scanning electron microscopy (SEM), respectively. Results indicated that the internal structure was improved significantly by steam activation through enlarging the specific surface area and enriching the porosity. The wheat straw char prepared by both rapid pyrolysis at 873K and activation by steam is better than others, whose DR surface area increases from 3.10 to 1099.99m{sup 2}/g. The N{sub 2} adsorption volume of steam activated biomass chars has been significant promoted.

Characterization of coal and char reactivity as a function of burn-off

Energy Technology Data Exchange (ETDEWEB)

Biede, O.; Swane Lund, J. [DTU, Dept. of Energy Engineering (Denmark); Holst Soerensen, L. [Risoe National Lab. (Denmark); Peck, R.E. [Arizona State University (United States)

1996-12-01

Four coal types have been tested under varying burning conditions in three high-temperature experimental facilities: A 1.3 MW test furnace, an entrained flow reactor and a down-fired tube furnace with a flat flame burner have been used to produce char samples. More than one hundred partly burned samples with burn-off from 30% to 99% have been collected from the experimental facilities, and analyzed in a thermogravimetric analyser (TGA) giving, besides the proximate data, a char burning profile of each individual sample, using a linear TGA-temperature ramp of 3 deg. C/minute. The burning profile derived by this procedure agrees well with reactivity profiles derived at a constant temperature. It is shown that small particle burn faster than large particles, and that small particles in general are more reactive than large particles. Particles burn faster when the oxygen partial pressure is increased, and apparently the oxygen partial pressure influences the combustion rate differently for different coal types. Except for one coal type, that apparently behaves differently in different burning environments, the ranking with respect to reactivity among the coals remains consistent at both high and at low temperatures. It is further shown how samples from one coal type varies more in behavior than samples from the other coal types, indicating a larger inhomogeneity of this coal. In general the reactivity of collected samples decrease with high-temperature burn-off. (au) 20 refs.

Production of fines during co-combustion of coal with biomass fuels by fragmentation and attrition

Energy Technology Data Exchange (ETDEWEB)

I. Gulyurtlu; D. Boavida; H. Lopes (and others) [DEECA-INETI, Lisbon (Portugal)

2005-07-01

Results are reported from a project funded by the RFCS Programme of the European Union. The aim is to investigate, experimentally and by modeling, the production of fine char and ash particles during co-combustion of coal with wastes and biofuels in circulating fluidized bed. Work was undertaken at installations of different scales. Polish and Colombian coals were base fuels. The additional fuels were two sewage sludges. Bed temperature, feeding system, sand particle size, devolatilisation behaviour and char burn-out were studied to verify their influence on the fine particle production. Modeling was also carried out to understand the mechanisms of fragmentation and attrition. Samples from bed and cyclone were collected to determine particle size distributions. 11 refs.

Study of the reaction of uranium and plutonium with bone char

International Nuclear Information System (INIS)

Silver, G.L.; Koenst, J.W.

1977-01-01

A study of the reaction of plutonium with a commercial bone char indicates that this bone char has a high capacity for removing plutonium from aqueous wastes. The adsorption of plutonium by bone char is pH dependent, and for plutonium(IV) polymer appears to be maximized near pH 7.3 for plutonium concentrations typical of some waste streams. Adsorption is affected by dissolved salts, especially calcium and phosphate salts. Freundlich isotherms representing the adsorption of uranium and plutonium have been prepared. The low potential imposed upon aqueous solutions by commercial bone char is adequate for reduction of hexavalent plutonium to a lower plutonium oxidation state

Time domain-nuclear magnetic resonance study of chars from southern hardwoods

International Nuclear Information System (INIS)

Elder, Thomas; Labbe, Nicole; Harper, David; Rials, Timothy

2006-01-01

Chars from the thermal degradation of silver maple (Acer saccharinum), red maple (Acer rubrum), sugar maple (Acer saccharum), and white oak (Quercus spp.), performed at temperatures from 250 to 350 o C, were examined using time domain-nuclear magnetic resonance spectroscopy. Prior to analysis, the chars were equilibrated under conditions insuring the presence of bound water only and both bound water and free water. Transverse relaxation times were found to be related to the moisture content of the chars, which varied with temperature. At elevated temperatures the number of signals assigned to free water decreased, indicative of an increase in pore size within the chars

Aspects of combustion behaviour of coals from some New Zealand lignite-coal regions determined by thermogravimetry

Energy Technology Data Exchange (ETDEWEB)

Benfell, K.E.; Beamish, B.B.; Rodgers, K.A. [University of Newcastle, Callaghan, NSW (Australia). Dept. of Geology

1997-08-25

The papers describes how thermogravimetric analysis of five Late Cretaceous and Cenozoic New Zealand lignites demonstrate that their combustion behaviour is distinct from that of subbituminous coals and may be characterised by peak temperature of 377-416{degree}C, maximum rate of combustion of 25-31 wt% min{sup -1}, and temperature of char burnout 421-497{degree}C. These parameters reflect variation in thermal behaviour associated with both the organic and inorganic constituents of the coal. The information obtained is additional to that provided by proximate analysis; the latter is insufficient to predict the combustion behaviour of the coals relative to one another. A post-combustion thermal event is seen among the lignites as in other low-rank coals combusting below 600{degree}C, which appears to be related to the organic sulphur content of the coal.

The importance of fuel properties in the formation of nitrogen oxides and in combustion; Polttoaineen ominaisuuksien merkitys typenoksidien muodostuksessa ja palamisessa

Energy Technology Data Exchange (ETDEWEB)

Aho, M.; Haemaelaeinen, J.; Rantanen, J.; Saastamoinen, J. [VTT Energia, Jyvaeskylae (Finland)

1996-12-01

Reactions of fuel nitrogen during pyrolysis and combustion of pulverized hvb coal, two peats and fir bark, thermal DeNOx-process and formation of N{sub 2}0 from char were studied experimentally in a pressurized entrained flow reactor. Mass loss of fuel, release of C,N,H and 0, and formation of NH{sub 3} and HCN were measured during pyrolysis (in N{sub 2} containing O{sub 2} < 50 ppm{sub vol}). Mass loss, and formation of NO, N{sub 2}O and NO{sub 2} through HCN and NH{sub 3} were measured during combustion at 5-4 vol% O{sub 2}. Thermal DeNOx process was studied at 2 and 15 bar at T= 700-950 deg C. Formation of N{sub 2}O from peat and its char was studied in a modified thermobalance. The rate of pyrolysis of high-volatile fuels (fir bark and peat) increased with pressure. A reverse trend was found with Polish hvb coal. The HCN/NH{sub 3} ratio in the flame was dependent on the fuel-O/fuel-N ratio and independent of pressure. Pressure did, however, increase the N{sub 2}O/NO ratio, because the concentrations of the key radicals in NO formation are decreased by pressure. With peats, the formation of N{sub 2}O increased slightly with pressure. The emissions of N{sub 2}O, however, doubled with wood bark when the pressure increased from 0.2 MPa to 0.8 MPa. Formation of NO{sub 2} increased clearly with pressure, and was fuel-dependent. One peat sample produced three times as much NO{sub 2} as the other under identical conditions. Pressure seemed to effect on Thermal DeNOx-process by lowering the effective temperature. Experiments with entrained flow of fuel and its char in project Liekki2-301, and experiments with single char and fuel particles in this project suggested that volatile nitrogen forms much more N{sub 2}O than char-N. Bed effects can change this situation in a real fluidized bed combustion process. (author)

Structural evolution of biomass char and its effect on the gasification rate

International Nuclear Information System (INIS)

Fatehi, Hesameddin; Bai, Xue-Song

2017-01-01

Highlights: • A comprehensive model was developed to describe the evolution of biomass char structure. • An effectiveness factor was used to account for the intra-particle chemical and physical processes. • The effect of the structural evolution of the multi-pore structure on biomass char reactivity was analyzed. • The multi-pore model yields results in satisfactory agreement with experiments. - Abstract: The evolution of char porous structure can affect the conversion rate of the char by affecting the intra-particle transport, especially in the zone II conversion regime. A multi-pore model based on the capillary pore theory is developed to take into account different conversion rates for pores with different radii. The model is valid for biomass chars produced under relatively low heating rates, when the original beehive structure of the biomass is not destroyed during the pyrolysis stage. The contribution of different pores with different radius is taken into account using an effectiveness factor presented for each pore radius with respect to different reactions. As the char conversion proceeds, the pore enlargement increases the contribution of micro-pores; consequently the effective surface area will increase. The increase in the effective surface area leads to an increased reactivity of char during the entire conversion process. This model is used to analyze the steam gasification process of biomass char of centimeter sizes. The results from the present multi-pore model are in better agreement with experimental data than those from a corresponding single pore model. Since the multi-pore model accommodates the detailed intra-particle transport, it is a useful basis toward developing a more predictive model for biomass char gasification.

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

CFD simulation of gas and particles combustion in biomass furnaces

Energy Technology Data Exchange (ETDEWEB)

Griselin, Nicolas

2000-11-01

In this thesis, gas and particle combustion in biomass furnaces is investigated numerically. The aim of this thesis is to use Computational Fluid Dynamics (CFD) technology as an effective computer based simulation tool to study and develop the combustion processes in biomass furnaces. A detailed model for the numerical simulation of biomass combustion in a furnace, including fixed-bed modeling, gas-phase calculation (species distribution, temperature field, flow field) and gas-solid two-phase interaction for flying burning particles is presented. This model is used to understand the mechanisms of combustion and pollutant emissions under different conditions in small scale and large scale furnaces. The code used in the computations was developed at the Division of Fluid Mechanics, LTH. The flow field in the combustion enclosure is calculated by solving the Favre-averaged Navier-Stokes equations, with standard {kappa} - {epsilon} turbulence closure, together with the energy conservation equation and species transport equations. Discrete transfer method is used for calculating the radiation source term in the energy conservation equation. Finite difference is used to solve the general form of the equation yielding solutions for gas-phase temperatures, velocities, turbulence intensities and species concentrations. The code has been extended through this work in order to include two-phase flow simulation of particles and gas combustion. The Favre-averaged gas equations are solved in a Eulerian framework while the submodels for particle motion and combustion are used in the framework of a Lagrangian approach. Numerical simulations and measurement data of unburned hydrocarbons (UHC), CO, H{sub 2}, O{sub 2} and temperature on the top of the fixed bed are used to model the amount of tar and char formed during pyrolysis and combustion of biomass fuel in the bed. Different operating conditions are examined. Numerical calculations are compared with the measured data. It is

Transformations of inorganic coal constituents in combustion systems

Energy Technology Data Exchange (ETDEWEB)

Helble, J.J. (ed.); Srinivasachar, S.; Wilemski, G.; Boni, A.A. (PSI Technology Co., Andover, MA (United States)); Kang, Shim-Gyoo; Sarofim, A.F.; Graham, K.A.; Beer, J.M. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Peterson, T.W.; Wendt, O.L.; Gallagher, N.B.; Bool, L. (Arizona Univ., Tucson, AZ (United States)); Huggins, F.E.; Huffman, G.P.; Shah, N.; Shah, A. (Kentucky Univ., Lexington

1992-11-01

This report contains the computer codes developed for the coal combustion project. In Subsection B.1 the FORTRAN code developed for the percolative fragmentation model (or the discrete model, since a char is expressed as a collection of discrete elements in a discrete space) is presented. In Subsection B.2 the code for the continuum model (thus named because mineral inclusions are distributed in a continuum space) is presented. A stereological model code developed to obtain the pore size distribution from a two-dimensional data is presented in Subsection B.3.

Influence of pH on pesticide sorption by soil containing wheat residue-derived char

International Nuclear Information System (INIS)

Sheng Guangyao; Yang Yaning; Huang Minsheng; Yang Kai

2005-01-01

Field burning of crop residues incorporates resulting chars into soil and may thus influence the environmental fate of pesticides in the soil. This study evaluated the influence of pH on the sorption of diuron, bromoxynil, and ametryne by a soil in the presence and absence of a wheat residue-derived char. The sorption was measured at pHs ∼3.0 and ∼7.0. Wheat char was found to be a highly effective sorbent for the pesticides, and its presence (1% by weight) in soil contributed >70% to the pesticide sorption (with one exception). The sorption of diuron was not influenced by pH, due to its electroneutrality. Bromoxynil becomes dissociated at high pHs to form anionic species. Its sorption by soil and wheat char was lower at pH ∼7.0 than at pH ∼3.0, probably due to reduced partition of the anionic species of bromoxynil into soil organic matter and its weak interaction with the carbon surface of the char. Ametryne in its molecular form at pH ∼7.0 was sorbed by char-amended soil via partitioning into soil organic matter and interaction with the carbon surface of the char. Protonated ametryne at pH ∼3.0 was substantially sorbed by soil primarily via electrostatic forces. Sorption of protonated ametryne by wheat char was also significant, likely due not only to the interaction with the carbon surface but also to interactions with hydrated silica and surface functional groups of the char. Sorption of ametryne by char-amended soil at pH ∼3.0 was thus influenced by both the soil and the char. Environmental conditions may thus significantly influence the sorption and behavior of pesticides in agricultural soils containing crop residue-derived chars. - Wheat char was effective for adsorption of pesticides in soil, with efficacy varying with pH and particular pesticides

Influence of pH on pesticide sorption by soil containing wheat residue-derived char

Energy Technology Data Exchange (ETDEWEB)

Sheng Guangyao [Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701 (United States)]. E-mail: gsheng@uark.edu; Yang Yaning [Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701 (United States); Huang Minsheng [Department of Environmental Science and Technology, East China Normal University, Shanghai 200062 (China); Yang Kai [Department of Environmental Science and Technology, East China Normal University, Shanghai 200062 (China)

2005-04-01

Field burning of crop residues incorporates resulting chars into soil and may thus influence the environmental fate of pesticides in the soil. This study evaluated the influence of pH on the sorption of diuron, bromoxynil, and ametryne by a soil in the presence and absence of a wheat residue-derived char. The sorption was measured at pHs {approx}3.0 and {approx}7.0. Wheat char was found to be a highly effective sorbent for the pesticides, and its presence (1% by weight) in soil contributed >70% to the pesticide sorption (with one exception). The sorption of diuron was not influenced by pH, due to its electroneutrality. Bromoxynil becomes dissociated at high pHs to form anionic species. Its sorption by soil and wheat char was lower at pH {approx}7.0 than at pH {approx}3.0, probably due to reduced partition of the anionic species of bromoxynil into soil organic matter and its weak interaction with the carbon surface of the char. Ametryne in its molecular form at pH {approx}7.0 was sorbed by char-amended soil via partitioning into soil organic matter and interaction with the carbon surface of the char. Protonated ametryne at pH {approx}3.0 was substantially sorbed by soil primarily via electrostatic forces. Sorption of protonated ametryne by wheat char was also significant, likely due not only to the interaction with the carbon surface but also to interactions with hydrated silica and surface functional groups of the char. Sorption of ametryne by char-amended soil at pH {approx}3.0 was thus influenced by both the soil and the char. Environmental conditions may thus significantly influence the sorption and behavior of pesticides in agricultural soils containing crop residue-derived chars. - Wheat char was effective for adsorption of pesticides in soil, with efficacy varying with pH and particular pesticides.

Type of litter determines the formation and properties of charred material during wildfires

Science.gov (United States)

Chavez, Bruno; Fonturbel, M. Teresa; Salgado, Josefa; García-Oliva, Felipe; Vega, Jose A.; Merino, Agustin

2014-05-01

Wildfire is one of the most important disturbances all over the World, affecting both the amount and composition of forest floor and mineral soils. In comparison with unburnt areas, wildfire-affected forest floor usually shows lower contents of labile C compounds and higher concentrations of recalcitrant aromatic forms. These changes in composition can have important impact on biogeochemical cycles and therefore ecosystem functions. Although burning of different types of litter can lead to different amount and types of pyrogenic compounds, this aspect has not been evaluated yet. The effect of wildfire on SOM composition and stability were evaluated in five major types of non-wood litter in Mediterranean ecosystems: Pinus nigra, E. arborea, P. pinaster, U. europaeus and Eucalyptus globulus. In each of these ecosystems, forest floor samples from different soil burn severities were sampled. Soil burnt severities were based on visual signs of changes in forest floor and deposition of ash. Pyrogenic carbon quality were analysed using elementary analysis, solid-state 13 C nuclear magnetic resonance spectroscopy, Reflectance Infrared Fourier Transform (FTIR) and thermal analysis (simultaneous DSC-TG). The study showed that the different types of litter influenced the formation and characteristics of charred material. They differed in the temperature at which they start to be formed, the amounts of charred compounds and in their chemical composition. The resulting charred materials from the different litter, showed an important variability in the degree of carbonitation/aromatization. Unlike the biochar obtained through pyrolysis of woody sources, which contains exclusively aromatic structures, in the charred material produced in some litter, lignin, cellulose and even cellulose persist even in the high soil burnt severity. Coinciding with increases in aromatic contents, important decreases in atomic H/C and O/C ratios were recorded. However, the values found in some

Relation between coal rank, char reactivity, textural properties and NO emissions

Energy Technology Data Exchange (ETDEWEB)

Arenillas, A.; Rubiera, F.; Parra, J.B.; Pis, J.J. [Instituto Nacional del Carbon, Oviedo (Spain)

1999-07-01

A low volatile bituminous coal was pyrolysed at different heating rates to produce chars with different textural properties. There was a linear relationship between char reactivity and active surface area. The effect of coal rank on coal char textural properties was studied using a range of bituminous coals. The influence of textural properties and reactivity on NO emissions, and on the heterogeneous reduction of NO is discussed. 6 refs., 2 figs., 2 tabs.

DDGS chars gasification with CO{sub 2}: a kinetic study using TG analysis

Energy Technology Data Exchange (ETDEWEB)

Meng, Xiangmei; Jong, Wiebren de; Fu, Ningjie; Verkooijen, Adrian H.M. [Delft University of Technology, Process and Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft (Netherlands)

2011-12-15

Dry Distiller's Grains with Solubles (DDGS) is a by-product during ethanol production from cereals which is currently mainly used as feedstock for cattle. With the growth of the ethanol industry, the increasing supply of DDGS may saturate the livestock feed market; thus, its potential applications need to be explored. DDGS gasification in a 100-kW{sub th} circulating fluidized bed (CFB) steam-O{sub 2} blown gasifier has been studied. However, the modeling of DDGS gasification process encounters difficulties due to the unavailable knowledge of DDGS char gasification kinetics. Therefore, in this paper, gasification kinetics of DDGS char with CO{sub 2} was investigated using thermogravimetric analysis (TGA). Two different types of char samples have been tested. Char type one (PYR-Char) was obtained after DDGS pyrolysis in a TGA at a final temperature of 750 C or 850 C for 20 min. Char type two (CFB-Char) was obtained after DDGS gasification in the 100-kW{sub th} CFB gasifier within the temperature range of 790 C to 820 C with a steam/biomass mass ratio of 0.81 and oxygen to biomass stoichiometric ratio of approximately 0.38. The influences of pyrolysis temperature (750 C, 850 C), heating rate (10 C/min, 30 C/min, 50 C/min, 70 C/min), CO{sub 2} concentration (10, 20, 30 vol.%), and gasification temperature (900 C, 1,000 C, 1,100 C) on the reaction rate of char-CO{sub 2} reaction were determined. Two representative gas-solid reaction models, the volumetric reaction model (VRM) and the shrinking core model (SCM) were applied in order to determine kinetic parameters. It was found that the calculated activation energy (E{sub a}) values using SCM were slightly lower than those using VRM. The calculated E{sub a} values for PYR-Char using both models were in the range of 100-165 kJ/mol, while the calculated E{sub a} values for CFB-Char were in the range of 55-100 kJ/mol. It was observed by scanning electron microscopy (SEM) that CFB-Char was more fragile and PYR-Char

Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

Energy Technology Data Exchange (ETDEWEB)

J. Helble; Clara Smith; David Miller

2009-08-31

The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.

Effects of nano-TiO2 on combustion and desulfurization

International Nuclear Information System (INIS)

Zhao, Yi; Wang, Shuqin; Shen, Yanmei; Lu, Xiaojuan

2013-01-01

Nanosized titanium oxide powder was prepared via the sol–gel process and characterized by transmission electron microscope. The effects of nano-TiO 2 on combustion characteristics of lignite, desulfurization in combustion and the properties of ashes were investigated. The calorific value of coals and the fusion point of the coal ashes were measured by calorimeter and ash fusion point determination meter; the components of coal ashes and the contents of combustible matters in ash were determined by chemical methods; the pore-size distribution and specific surface area of the coal ash were analyzed by surface area analyzer. A thermogravimetric analyzer was used to investigate the effect of nano-TiO 2 on combustion. The results showed that the calorific value of the coal and the fusion temperature of the coal ash were lowered by adding CaO, while on the other hand adding nano-TiO 2 to coal increased the calorific value and the melting temperature effectively. Meanwhile, the coal combustion efficiency and desulfurization in combustion could be effectively improved by the co-action of TiO 2 . - Highlights: • The burn-off rate of coals was raised and the combustible contents were reduced by adding nano-TiO 2 . • The desulfurization in combustion can be achieved by adding CaO, but the combustion efficiency was inhibited. • Nano-TiO 2 can promote the transfer rate of oxygen from gas phase to the surface of char

Characterization of bio char derived from tapioca skin

Science.gov (United States)

Hasnan, F. I.; Iamail, K. N.; Musa, M.; Jaapar, J.; Alwi, H.; Hamid, K. K. K.

2018-03-01

Pyrolysis of tapioca skin was conducted to produce bio chars in the range between 500°C–800°C. Surface modification treatment were performed on bio chars by using chemicals within 24 hours at 30°C and hot water within 1 hour to enhance the bio char’s adsorption properties according to surface area, pore volume, pore size, crystallinity structure and functional groups. The samples were characterized by using BET, XRD, FTIR and Methylene Blue adsorption. Based on BET result, it showed the surface area increased as the pyrolysis temperature increased followed by pore volume and pore size for S0. The optimum temperature for SNaOH, SHW and SMeOH was at 600°C, 700°C and 800°C with the surface area of 75.9874, 274.5066 and 351.5531 m2/g respectively compared to S0 while SP3HO4 has the worst result since it felt on macroporous structure. The percentage of MB adsorption was followed the size of bio chars surface area. Based on FTIR result, at temperature 500°C to 700°C, the bio chars still have functional groups while at 800°C, many functional groups were diminished due to high temperature struck on them. XRD result showed all the bio chars were amorphous. In conclusion, the best surface modification treatment was by Methanol followed by hot water and Sodium Hydroxide at temperature of 700°C and 800°C while Ortho-Phosphoric acid was the worst one and was not suitable for bio char’s surface modification for adsorption purpose.

Catalytic combustion in small wood burning appliances

Energy Technology Data Exchange (ETDEWEB)

Oravainen, H [VTT Energy, Jyvaeskylae (Finland)

1997-12-31

There is over a million hand fired small heating appliances in Finland where about 5,4 million cubic meters of wood fuel is used. Combustion in such heating appliances is a batch-type process. In early stages of combustion when volatiles are burned, the formation of carbon monoxide (CO) and other combustible gases are difficult to avoid when using fuels that have high volatile matter content. Harmful emissions are formed mostly after each fuel adding but also during char burnout period. When the CO-content in flue gases is, say over 0.5 %, also other harmful emissions will be formed. Methane (CH{sub 4}) and other hydrocarbons are released and the amount of polycyclic aromatic hydrocarbons (PAH)-compounds can be remarkable. Some PAH-compounds are very carcinogenic. It has been estimated that in Finland even more than 90 % of hydrocarbon and PAH emissions are due to small scale wood combustion. Emissions from transportation is excluded from these figures. That is why wood combustion has a net effect on greenhouse gas phenomena. For example carbon monoxide emissions from small scale wood combustion are two fold compared to that of energy production in power plants. Methane emission is of the same order as emission from transportation and seven fold compared with those of energy production. Emissions from small heating appliances can be reduced by developing the combustion techniques, but also by using other means, for example catalytic converters. In certain stages of the batch combustion, temperature is not high enough, gas mixing is not good enough and residence time is too short for complete combustion. When placed to a suitable place inside a heating appliance, a catalytic converter can oxidize unburned gases in the flue gas into compounds that are not harmful to the environment. (3 refs.)

Catalytic combustion in small wood burning appliances

Energy Technology Data Exchange (ETDEWEB)

Oravainen, H. [VTT Energy, Jyvaeskylae (Finland)

1996-12-31

There is over a million hand fired small heating appliances in Finland where about 5,4 million cubic meters of wood fuel is used. Combustion in such heating appliances is a batch-type process. In early stages of combustion when volatiles are burned, the formation of carbon monoxide (CO) and other combustible gases are difficult to avoid when using fuels that have high volatile matter content. Harmful emissions are formed mostly after each fuel adding but also during char burnout period. When the CO-content in flue gases is, say over 0.5 %, also other harmful emissions will be formed. Methane (CH{sub 4}) and other hydrocarbons are released and the amount of polycyclic aromatic hydrocarbons (PAH)-compounds can be remarkable. Some PAH-compounds are very carcinogenic. It has been estimated that in Finland even more than 90 % of hydrocarbon and PAH emissions are due to small scale wood combustion. Emissions from transportation is excluded from these figures. That is why wood combustion has a net effect on greenhouse gas phenomena. For example carbon monoxide emissions from small scale wood combustion are two fold compared to that of energy production in power plants. Methane emission is of the same order as emission from transportation and seven fold compared with those of energy production. Emissions from small heating appliances can be reduced by developing the combustion techniques, but also by using other means, for example catalytic converters. In certain stages of the batch combustion, temperature is not high enough, gas mixing is not good enough and residence time is too short for complete combustion. When placed to a suitable place inside a heating appliance, a catalytic converter can oxidize unburned gases in the flue gas into compounds that are not harmful to the environment. (3 refs.)

Sorption of diuron, atrazine, and copper ion on chars with long-term natural oxidation in soils

Science.gov (United States)

Cheng, C.; Lin, T.; Lai, C.

2011-12-01

Biochar has been proposed as a measure to sequestrate carbon (C) and to increase soil fertility in sustainable agriculture. However, its sorption characteristics to herbicides, such as lowing herbicides efficacy, may constrain its agricultural application. This assertion may be arguable because most studies so far were conducted with the newly produced char and barely considered the "ageing effect" of old char since it could be oxidized over long time. In this study, historical char samples were collected and compared with the newly produced char. Batch sorption studies of diuron, atrazine, and copper ion onto chars was performed. Greater sorption of Cu was observed on the historical char samples and reached a saturated sorption at 30 mg g-1 for Cu, much higher adsorption value than newly produced char at 4 mg g-1. In contrast, sorption of diuron and atrazine on newly produced char had the highest sorption capacity than the historical char samples. The historical chars also had much higher negative charge than the newly produced char, but its surface area were lower than the new char. The results indicated that change in surface functional groups through natural oxidation rather than the change of surface area may have more pronounced influences on sorption characteristics, in which the negative charge on the historical chars' surface could hinder the adsorption of diuron and atrazine while enhance the sorption to copper ion. Biological assay to test the toxicity of diuron and copper ion for both historical and new chars on rye seed were conducted and will be presented in our poster.

CHARCOAL PACKED FURNACE FOR LOW-TECH CHARRING OF BONE

DEFF Research Database (Denmark)

Jacobsen, P.; Dahi, Elian

1997-01-01

A low-tech furnace for charring of raw bone using char coal is developed and tested. The furnace consists of a standard oil drum, fitted with simple materials as available in every market in small towns in developing counties. 80 kg of raw bone and 6 kg of charcoal are used for production of 50 kg...

The carbon dioxide gasification characteristics of biomass char samples and their effect on coal gasification reactivity during co-gasification.

Science.gov (United States)

Mafu, Lihle D; Neomagus, Hein W J P; Everson, Raymond C; Okolo, Gregory N; Strydom, Christien A; Bunt, John R

2018-06-01

The carbon dioxide gasification characteristics of three biomass char samples and bituminous coal char were investigated in a thermogravimetric analyser in the temperature range of 850-950 °C. Char SB exhibited higher reactivities (R i , R s , R f ) than chars SW and HW. Coal char gasification reactivities were observed to be lower than those of the three biomass chars. Correlations between the char reactivities and char characteristics were highlighted. The addition of 10% biomass had no significant impact on the coal char gasification reactivity. However, 20 and 30% biomass additions resulted in increased coal char gasification rate. During co-gasification, chars HW and SW caused increased coal char gasification reactivity at lower conversions, while char SB resulted in increased gasification rates throughout the entire conversion range. Experimental data from biomass char gasification and biomass-coal char co-gasification were well described by the MRPM, while coal char gasification was better described by the RPM. Copyright © 2018 Elsevier Ltd. All rights reserved.

Report on results of research. Basic studies on characteristics of coal char gasification under pressure; Sekitan char no kaatsuka ni okeru gas ka tokuseino kiso kenkyu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1981-03-01

This paper explains basic studies on characteristics of coal char gasification under pressure. Hydro-gasification of coal needs as a gasifying agent a large amount of hydrogen, which is effectively produced by the water gasification of exhaust unreacted residual char. In fiscal 1975, gasification was tested on Taiheiyo coal carbonized char by an atmospheric fluidized gasifier of 28 mm bore. In fiscal 1976, experiment was conducted under pressure by fully improving the auxiliary safety equipment. The char and gas yield increased with higher pressure in pressurized carbonization by an autoclave. In fiscal 1977, clinker was successfully prevented by using quartz sand for a fluidized medium. In fiscal 1978, two-stage continuous gasification was examined. In fiscal 1979, correlation was determined between operation factors such as gasification pressure, temperature, etc., and clinker formation/char reactivity. An experiment was conducted for particle pop-out using a pressurized fluidized bed of 100 mm inner diameter, with the pop-out quantity found to be proportional to the 0.38th power of a pressure. A high pressure fluidized gasifier was built having a char processing capacity of 1 t/day, 20 atmospheric pressure, and an inner diameter of 100 mm. In fiscal 1980, this device was continuously operated, elucidating problems for the practicability. (NEDO)

Gas cleaning with hot char beds studied by stable isotopes

DEFF Research Database (Denmark)

Egsgaard, Helge; Ahrenfeldt, Jesper; Ambus, Per

2014-01-01

The chemistry taking place in a high temperature char bed used for binding aromatic tar compounds has been studied in detail. 13C labelled tar compounds were used to trace the incorporation into the char bed using isotope ratio mass spectrometry (IRMS) and GC-MS. Furthermore, compounds labelled...

Modifying Char Dustcake Pressure Drop Using Particulate Additives

Energy Technology Data Exchange (ETDEWEB)

Landham, C.; Dahlin, R.S.; Martin, R.A.; Guan, X.

2002-09-19

Coal gasification produces residual particles of coal char, coal ash, and sorbent that are suspended in the fuel gas stream exiting the gasifier. In most cases, these particles (referred to, hereafter, simply as char) must be removed from the stream prior to sending the gas to a turbine, fuel cell, or other downstream device. Currently, the most common approach to cleaning the gas stream at high temperature and pressure is by filtering the particulate with a porous ceramic or metal filter. However, because these dusts frequently have small size distributions, irregular morphology, and high specific surface areas, they can have very high gas flow resistance resulting in hot-gas filter system operating problems. Typical of gasification chars, the hot-gas filter dustcakes produced at the Power Systems Development Facility (PSDF) during recent coal gasification tests have had very high flow resistance (Martin et al, 2002). The filter system has been able to successfully operate, but pressure drops have been high and filter cleaning must occur very frequently. In anticipation of this problem, a study was conducted to investigate ways of reducing dustcake pressure drop. This paper will discuss the efficacy of adding low-flow-resistance particulate matter to the high-flow-resistance char dustcake to reduce dustcake pressure drop. The study had two parts: a laboratory screening study and confirming field measurements at the PSDF.

An experimental study of factors in the recovery of plutonium from combustible wastes treated by incineration, pyrolysis and other processes

International Nuclear Information System (INIS)

Bamber, D.C.; McDonald, L.A.; Roberts, W.G.; Sutcliffe, P.W.; Wilkins, J.D.

1984-01-01

The work described in this report is concerned with the incineration and pyrolysis of plutonium-contaminated combustible wastes, the leaching of the ashes and chars and the subsequent treatment of the leach solutions. A range of ashes and chars have been prepared from a range of plutonium-contaminated materials covering a variety of combustible materials (e.g. PVC, neoprene, Hypalon) and plutonium contaminants [e.g. PuO 2 , Pu(NO 3 ) 4 , (U, Pu)O 2 ]. Treatment temperatures in the range of 550-900 0 C have been investigated, the best results being obtained at or below 700 0 C with pyrolysis followed by char oxidation being the favoured process. A number of methods for treatment of the leach solutions have been considered and some have been investigated experimentally. Extraction of plutonium and americium with tributylphosphate (TBP) from a leach solution conditioned to 0.1 M H/+5 M NO 3 - has been studied. The key stage has been found to be the conditioning step where precautions must be taken to ensure that plutonium-containing precipitates and non-extractable plutonium are not formed. Consideration has also been given to treatment of the americium containing raffinates from a high acid TBP extraction and some methods have been investigated. A range of simple washing experiments have been carried out in order to compare the process with incineration/pyrolysis

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)

Effect of pyrolysis pressure and heating rate on radiata pine char structure and apparent gasification reactivity

Energy Technology Data Exchange (ETDEWEB)

E. Cetin; R. Gupta; B. Moghtaderi [University of Newcastle, Callaghan, NSW (Australia). Discipline of Chemical Engineering, Faculty of Engineering and Built Environment, School of Engineering

2005-07-01

The knowledge of biomass char gasification kinetics has considerable importance in the design of advanced biomass gasifiers, some of which operate at high pressure. The char gasification kinetics themselves are influenced by char structure. In this study, the effects of pyrolysis pressure and heating rate on the char structure were investigated using scanning electron microscopy (SEM) analysis, digital cinematography, and surface area analysis. Char samples were prepared at pressures between 1 and 20 bar, temperatures ranging from 800 to 1000{degree}C, and heating rates between 20 and 500{degree}C/s. Our results indicate that pyrolysis conditions have a notable impact on the biomass char morphology. Pyrolysis pressure, in particular, was found to influence the size and the shape of char particles while high heating rates led to plastic deformation of particles (i.e. melting) resulting in smooth surfaces and large cavities. The global gasification reactivities of char samples were also determined using thermogravimetric analysis (TGA) technique. Char reactivities were found to increase with increasing pyrolysis heating rates and decreasing pyrolysis pressure. 22 refs., 8 figs., 2 tabs.

Bitumen on Water: Charred Hay as a PFD (Petroleum Flotation Device

Directory of Open Access Journals (Sweden)

Nusrat Jahan

2015-10-01

Full Text Available Global demand for petroleum keeps increasing while traditional supplies decline. One alternative to the use of conventional crude oils is the utilization of Canadian bitumen. Raw bitumen is a dense, viscous, semi-liquid that is diluted with lighter crude oil to permit its transport through pipelines to terminals where it can then be shipped to global markets. When spilled, it naturally weathers to its original form and becomes dense enough to sink in aquatic systems. This severely limits oil spill recovery and remediation options. Here we report on the application of charred hay as a method for modifying the surface behavior of bitumen in aquatic environments. Waste or surplus hay is abundant in North America. Its surface can easily be modified through charring and/or chemical treatment. We have characterized the modified and charred hay using solid-state NMR, contact angle measurements and infrared spectroscopy. Tests of these materials to treat spilled bitumen in model aquatic systems have been undertaken. Our results indicate that bitumen spills on water will retain their buoyancy for longer periods after treatment with charred hay, or charred hay coated with calcium oxide, improving recovery options.

Characterisation of fuels for advanced pressurised combustion

Energy Technology Data Exchange (ETDEWEB)

Zevenhoven, R; Hupa, M; Backman, P; Forssen, M; Karlsson, M; Kullberg, M; Sorvari, V; Uusikartano, T [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group; Nurk, M [Tallinskij Politekhnicheskij Inst., Tallinn (Estonia)

1997-10-01

The objective of the research was to determine a set of fuel characteristics which quantify the behaviour of a fuel in a typical pressurised combustor or gasifier environment, especially in hybrid processes such as second generation PFBC. One specific aspect was to cover a wide range of fuels, including several coal types and several grades of peat and biomasses: 7 types of coal, 2 types of peat, 2 types of wood, 2 types of black liquor, Estonian oil shale and Venezuelan Orimulsion were studied. The laboratory facilities used are a pressurised thermogravimetric reactor (PTGR), a pressurised grid heater (PGH) and an atmospheric entrained flow quartz tube reactor, with gas analysis, which can be operated as a fixed bed reactor. A major part of the work was related to fuel devolatilisation in the PGH and sequential devolatilisation and char gasification (with carbon dioxide or steam) in the PTGR. The final part of that work is reported here, with the combustion of Estonian oil shale at AFBC or PFBC conditions as additional subject. Devolatilisation of the fuels at atmospheric pressure in nitrogen while monitoring gaseous exhausts, followed by ultimate analysis of the chars has been reported earlier. Here, results on the analysis of the reduction of NO (with and without CO) on chars at atmospheric pressure in a fixed bed reactor are reported. Finally, a comparison is given between experimental results and direct numerical simulation with several computer codes, i.e. PyroSim, developed at TU Graz, Austria, and the codes Partikkeli, Pisara and Cogas, which were provided by VTT Energy, Jyvaeskylae

Effect of filling surface-treated pyrolytic char on resistivity of rubber films

Directory of Open Access Journals (Sweden)

Pattraporn Yamkaya

2015-03-01

Full Text Available In this research, natural rubber (NR films filled with pyrolytic tire char, carbon black N234 and N330 were compared for their electrical resistivity. The filler loading was varied to be 5, 10, 15, 20 and 25% of dry rubber content. The effect of surfactant which is 2 %w/v sodium dodecyl sulfate (SDS was also investigated. In the experiments, it was necessary to disperse the pyrolytic char in ethyl alcohol while disperse carbon black (CB in ammonium hydroxide solution prior to mixing with the rubber latex and the filled NR film was prepared by casting the mixture on a plate. It was found that increasing the amount of pyrolytic char in the NR film could lower its resistivity. The surfactant, SDS, could help better dispersion of both CB and pyrolytic char, thereby decreasing the resistivity. In a separate experiment where hexane vapor was absorbed in NR film without surfactant, in the first 30 seconds, the rate of increasing resistivity of the CB-filled film was not seen as clearly as that of pyrolytic-char-filled film. For the films with surfactant, the slow increase in resistivity of the NR films filled with N330 and pyrolytic char during adsorbing hexane vapor was observed.

Heat Transfer in a Fixed Bed of Straw Char

DEFF Research Database (Denmark)

Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Jensen, Anker

2003-01-01

A model for the thermal conductivity of a straw char bed has been developed. The model extends the work of Yagi and Kunii to describe heat transfer in a bed of cylinders, using a relationship between the interparticle distance and the external porosity. To verify the model, thermal conductivity...... the experimental uncertainty over the range of conditions investigated. The heat transfer model was used in a parametric study to evaluate the effect of gas flow rate, particle diameter, porosity, and temperature on the thermal conductivity in a straw char bed....... experiments were performed on shredded and un-shredded straw char samples, varying particle size, bed packing (loose or dense), and temperature. Predictions with the model, using the measured external porosity and particle diameter as input parameters, are in agreement with measurements within...

Preparation of porous bio-char and activated carbon from rice husk by leaching ash and chemical activation.

Science.gov (United States)

Ahiduzzaman, Md; Sadrul Islam, A K M

2016-01-01

Preparation porous bio-char and activated carbon from rice husk char study has been conducted in this study. Rice husk char contains high amount silica that retards the porousness of bio-char. Porousness of rice husk char could be enhanced by removing the silica from char and applying heat at high temperature. Furthermore, the char is activated by using chemical activation under high temperature. In this study no inert media is used. The study is conducted at low oxygen environment by applying biomass for consuming oxygen inside reactor and double crucible method (one crucible inside another) is applied to prevent intrusion of oxygen into the char. The study results shows that porous carbon is prepared successfully without using any inert media. The adsorption capacity of material increased due to removal of silica and due to the activation with zinc chloride compared to using raw rice husk char. The surface area of porous carbon and activated carbon are found to be 28, 331 and 645 m(2) g(-1) for raw rice husk char, silica removed rice husk char and zinc chloride activated rice husk char, respectively. It is concluded from this study that porous bio-char and activated carbon could be prepared in normal environmental conditions instead of inert media. This study shows a method and possibility of activated carbon from agro-waste, and it could be scaled up for commercial production.

Combustion behavior and kinetics of low-lipid microalgae via thermogravimetric analysis.

Science.gov (United States)

Gai, Chao; Liu, Zhengang; Han, Guanghua; Peng, Nana; Fan, Aonan

2015-04-01

Thermogravimetric analysis and differential thermal analysis were employed to investigate combustion characteristics of two low-lipid microalgae, Chlorella pyrenoidosa (CP) and Spirulina platensis (SP) and iso-conversional Starink approach was used to calculate the kinetic parameters in the present study. The results showed that three stages of mass loss, including dehydration, devolatilization and char oxidation, were observed during combustion of both of two low-lipid microalgae. The whole weight loss of combustion of two microalgae was both shifted to higher temperature zones with increased heating rates from 10 to 40 K/min. In the 0.1-0.9 conversion range, the apparent activation energy of CP increased first from 51.96 to 79.53 kJ/mol, then decreased to 55.59 kJ/mol. Finally, it slightly increased to 67.27 kJ/mol. In the case of SP, the apparent activation energy gradually increased from 68.51 to 91.06 kJ/mol. Copyright © 2015 Elsevier Ltd. All rights reserved.

Co-gasification of tire and biomass for enhancement of tire-char reactivity in CO2 gasification process.

Science.gov (United States)

Lahijani, Pooya; Zainal, Zainal Alimuddin; Mohamed, Abdul Rahman; Mohammadi, Maedeh

2013-06-01

In this investigation, palm empty fruit bunch (EFB) and almond shell (AS) were implemented as two natural catalysts rich in alkali metals, especially potassium, to enhance the reactivity of tire-char through co-gasification process. Co-gasification experiments were conducted at several blending ratios using isothermal Thermogravimetric analysis (TGA) under CO2. The pronounced effect of inherent alkali content of biomass-chars on promoting the reactivity of tire-char was proven when acid-treated biomass-chars did not exert any catalytic effect on improving the reactivity of tire-char in co-gasification experiments. In kinetic studies of the co-gasified samples in chemically-controlled regime, modified random pore model (M-RPM) was adopted to describe the reactive behavior of the tire-char/biomass-char blends. By virtue of the catalytic effect of biomass, the activation energy for tire-char gasification was lowered from 250 kJ/mol in pure form 203 to 187 kJ/mol for AS-char and EFB-char co-gasified samples, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Electron paramagnetic resonance and dynamic nuclear polarization of char suspensions: surface science and oximetry

International Nuclear Information System (INIS)

Clarkson, R.B.; Odintsov, B.M.; Ceroke, P.J.; Ardenkjaer-Larsen, J.H.; Fruianu, M.; Belford, R.L.

1998-01-01

Carbon chars have been synthesized in our laboratory from a variety of starting materials, by means of a highly controlled pyrolysis technique. These chars exhibit electron paramagnetic resonance (EPR) line shapes which change with the local oxygen concentration in a reproducible and stable fashion; they can be calibrated and used for oximetry. Biological stability and low toxicity make chars good sensors for in vivo measurements. Scalar and dipolar interactions of water protons at the surfaces of chars may be utilized to produce dynamic nuclear polarization (DNP) of the 1 H nuclear spin population in conjunction with electron Zeeman pumping. Low-frequency EPR, DNP and DNP-enhanced MRI all show promise as oximetry methods when used with carbon chars. (author)

Bio-char derived from sewage sludge by liquefaction: Characterization and application for dye adsorption

Energy Technology Data Exchange (ETDEWEB)

Leng, Lijian [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Yuan, Xingzhong, E-mail: yxz@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Huang, Huajun [School of Land Resources and Environment, Jiangxi Agricultural University, Nanchang 330045 (China); Shao, Jianguang; Wang, Hou [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Chen, Xiaohong [School of Business, Central South University, Changsha 410083 (China); Zeng, Guangming [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China)

2015-08-15

Graphical abstract: - Highlights: • SS liquefaction bio-chars were effective on MG and MB removal from aqueous. • MG adsorption capacity depended strongly on carboxylic and phenolic groups. • Metal release accounted for nearly 30% of the total MG adsorbed on bio-chars. • Acetone and low temperature favor effective adsorbent production by liquefaction. - Abstract: Bio-chars produced by liquefaction of sewage sludge with methanol, ethanol, or acetone as the solvent at 260–380 °C were characterized in terms of their elemental composition, thermogravimetric characteristics, surface area and pore size distribution, and oxygen-containing functional groups composition. The surface area and total volume of the bio-chars were low, but the contents of oxygen-containing functional groups were high. The bio-chars were effective on Malachite green (MG) and Methylene blue (MB) removal from aqueous solution. The MG adsorption equilibrium data showed excellent fit to the Langmuir model and the kinetic data fitted well to the Pseudo-second-order model. Thermodynamic investigations indicated that MG adsorption on bio-char was spontaneous and endothermic. The MG adsorption mechanism appears to be associated with cation release and functional group participation. Additionally, liquefaction of SS with acetone as the solvent at low temperature (280 °C) would favor the production of bio-char adsorbent in terms of bio-char yield and MG and MB adsorption capacity.

Kinetics of devolatilization and oxidation of a pulverized biomass in an entrained flow reactor under realistic combustion conditions

Energy Technology Data Exchange (ETDEWEB)

Jimenez, Santiago [LITEC-CSIC (Spanish Council for Scientific Research), Maria de Luna 10, 50018 Zaragoza (Spain); Remacha, Pilar; Ballester, Javier [LITEC-CSIC (Spanish Council for Scientific Research), Maria de Luna 10, 50018 Zaragoza (Spain); Fluid Mechanics Group, University of Zaragoza, Maria de Luna 3, 50018 Zaragoza (Spain); Ballesteros, Juan C.; Gimenez, Antonio [ENDESA GENERACION, S.A., Ribera del Loira 60, 28042 Madrid (Spain)

2008-03-15

In this paper the results of a complete set of devolatilization and combustion experiments performed with pulverized ({proportional_to}500 {mu}m) biomass in an entrained flow reactor under realistic combustion conditions are presented. The data obtained are used to derive the kinetic parameters that best fit the observed behaviors, according to a simple model of particle combustion (one-step devolatilization, apparent oxidation kinetics, thermally thin particles). The model is found to adequately reproduce the experimental trends regarding both volatile release and char oxidation rates for the range of particle sizes and combustion conditions explored. The experimental and numerical procedures, similar to those recently proposed for the combustion of pulverized coal [J. Ballester, S. Jimenez, Combust. Flame 142 (2005) 210-222], have been designed to derive the parameters required for the analysis of biomass combustion in practical pulverized fuel configurations and allow a reliable characterization of any finely pulverized biomass. Additionally, the results of a limited study on the release rate of nitrogen from the biomass particle along combustion are shown. (author)

The combustion of biomass - the impact of its types and combustion technologies on the emission of nitrogen oxide

Directory of Open Access Journals (Sweden)

Mladenović Milica R.

2016-01-01

Full Text Available Harmonization of environmental protection and the growing energy needs of modern society promote the biomass application as a replacement for fossil fuels and a viable option to mitigate the green house gas emissions. For domestic conditions this is particularly important as more than 60% of renewables belongs to biomass. Beside numerous benefits of using biomass for energy purposes, there are certain drawbacks, one of which is a possible high emission of NOx during the combustion of these fuels. The paper presents the results of the experiments with multiple biomass types (soybean straw, cornstalk, grain biomass, sunflower oil, glycerin and paper sludge, using different combustion technologies (fluidized bed and cigarette combustion, with emphasis on the emission of NOx in the exhaust gas. A presentation of the experimental installations is given, as well as an evaluation of the effects of the fuel composition, combustion regimes and technology on the NOx emissions. As the biomass combustion took place at temperatures low enough that thermal and prompt NOx can be neglected, the conclusion is the emissions of nitrogen oxides primarily depend on the biomass composition- it is increasing with the increase of the nitrogen content, and decreases with the increase of the char content which provides catalytic surface for NOx reduction by CO. [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 i br. III42011: Development and improvement of technologies for efficient use of energy of several forms of agricultural and forest biomass in an environmentally friendly manner, with the possibility of cogeneration

Formation of dioxins and furans during combustion of treated wood

Energy Technology Data Exchange (ETDEWEB)

Tame, Nigel W.; Dlugogorski, Bogdan Z.; Kennedy, Eric M. [Process Safety and Environment Protection Research Group, School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia)

2007-08-15

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F, dioxin) are produced in combustion of wood treated with copper-based preservatives. This review summarises and analyses the pertinent literature on the role of preservatives in the formation of dioxin in the low-temperature, vitiated environment that exists in the domestic combustion of wood, and in large-scale fires. Until recently, the role of preservatives was not thoroughly examined in the literature with respect to fires, as incineration attracted most of the research focus. However, latest studies have demonstrated that some current and emerging wood preservatives significantly increase dioxin formation during combustion in domestic stoves and in fires. The following pathways are identified: (i) copper, a common biocide that is chemically bound to the wood, is an important dioxin catalyst, (ii) preservative metals promote smouldering of wood char following cessation of flaming, providing the required temperature environment for dioxin formation, and (iii) chlorinated organics added as secondary preservative components yield dioxin precursors upon thermal decomposition. These conclusions indicate that it remains hazardous to dispose of preservative impregnated timber via domestic combustion even if arsenic is not present. (author)

Regenerable mixed copper-iron-inert support oxygen carriers for solid fuel chemical looping combustion process

Energy Technology Data Exchange (ETDEWEB)

Siriwardane, Ranjani V.; Tian, Hanjing

2016-12-20

The disclosure provides an oxygen carrier for a chemical looping cycle, such as the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The oxygen carrier is comprised of at least 24 weight % (wt %) CuO, at least 10 wt % Fe2O3, and an inert support, and is typically a calcine. The oxygen carrier exhibits a CuO crystalline structure and an absence of iron oxide crystalline structures under XRD crystallography, and provides an improved and sustained combustion reactivity in the temperature range of 600.degree. C.-1000.degree. C. particularly for solid fuels such as carbon and coal.

Combustion behavior of briquettes from oil palm's empty fruit bunch

Energy Technology Data Exchange (ETDEWEB)

Pratoto, A. [Andalas Univ., Padang (Indonesia). Dept. of Mechanical Engineering

2006-07-01

Empty fruit bunch (EFB) briquettes from palm plantations are now being considered as a renewable energy source in Indonesia. This paper provided details of a study that investigated the combustion behaviour of an EFB briquette. Thermogravimetry was used to study the briquettes under dynamic conditions at 50 degrees C in a muffle furnace. Thermal decomposition rates and phases were identified, and the effect of the briquette's size on the decomposition rate was evaluated by comparing the combustion behaviour of the briquette to that of loose EFB materials. Rates of devolatilization and char oxidation were also examined. Results of the derivative thermogravimetry (DTG) analysis showed that larger briquettes did not exhibit a sharp peak on the DTG curve. Results suggested that heat transfer was predominant over the kinetic reaction during combustion. The ignition temperature of the briquettes was comparable to typical lignocellulose biomass. Peak combustion temperatures for loose EFB were only slightly lower than other types of biomass. Maximum combustion rates decreased with the size of the fuel. It was concluded that small briquettes are suitable for applications where high rates of heat are required. 16 refs., 1 tab., 6 figs.

Production and characterization of Lemna minor bio-char and its catalytic application for biogas reforming

International Nuclear Information System (INIS)

Muradov, Nazim; Fidalgo, Beatriz; Gujar, Amit C.; Garceau, Nathaniel; T-Raissi, Ali

2012-01-01

Pyrolysis of fast-growing aquatic biomass - Lemna minor (commonly known as duckweed) with the emphasis on production, characterization and catalytic application of bio-char is reported in this paper. The yield of bio-char was determined as a function of L. minor pyrolysis temperature and sweep gas flow rate. It was found that the pore development during L. minor pyrolysis was not significant and the changes in the reaction conditions (temperature and sweep gas flow rate) did not alter markedly the textural characteristics and BET surface area of the bio-char produced. Thermogravimetric/differential thermogravimetric (TG/DTG) analyses of L. minor and different bio-char samples in inert (helium) and oxidative (air) media showed substantial differences in their TG/DTG patterns. A comparison of scanning electron micrographs (SEM) of L. minor, bio-char and ash indicated that the basic structural features of L. minor remained intact and were not affected by thermolysis. The inorganic ash content of L. minor derived bio-char is significantly higher than that of typical terrestrial (plant) biomass. The energy dispersive spectroscopic (EDS) analysis of L. minor ash showed that it mostly consisted of silica, and small quantities of Na, K and Ca compounds. The treatment of bio-char with CO 2 at 800 °C increased its BET surface area. It was found that CO 2 -treated bio-char exhibited appreciable initial catalytic activity in biogas reforming. -- Highlights: ► New data on characterization of bio-chars derived from Lemna minor are presented. ► Effect of pyrolysis operational parameters on bio-char properties is determined. ► Basic skeletal structure of Lemna minor leaflets does not change during pyrolysis. ► Bio-chars show an appreciable initial catalytic activity for biogas reforming.

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

Gasification of bio char from empty fruit bunch in a fluidized bed

International Nuclear Information System (INIS)

Nsamba Hussein Kisiki; Amran Mohammad Salleh; Wan Azlina; Hamdan Yusof

2010-01-01

Full text: Bio char from empty fruit bunch was gasified in a fluidized bed reactor using compressed air as a gasifying agent. The experiment was conducted in the temperature ranges of 500-850 degree Celsius and the equivalence ratio, temperature and size of the feedstock was varied. A series of parameters such as gas yield, overall carbon conversion, gas quality, and composition, were measured as a function of temperature, equivalence ratio and temperature. Results obtained were compared to the actual values of coal and other gasification feedstock reveal that, bio char has the potential to replace coal as a gasification agent in power plants .Hydrogen gas from bio char was also optimized during the experiment. There is great potential of making Hydrogen from Bio char through thermo chemical gasification It was observed that it has a very great potential of being upgraded to Fischer Tropsh fuels. There is a great opportunity of using this char from empty fruit bunch as an alternative fuel in power plants and all the adverse effects of coal gasification can be counteracted. (author)

Adsorption characteristics of SO{sub 2}, NO by steam activated biomass chars

Energy Technology Data Exchange (ETDEWEB)

Lu, Fei; Shu, Tong; Wang, Kuan; Lu, Ping [Nanjing Normal Univ. (China). School of Energy and Mechanical Engineering

2013-07-01

Wheat straw and rice husk collected from the suburb of Nanjing, China, were prepared to different kinds of steam activated biomass-based chars, and the adsorption characteristics of the biomass-based chars was carried out in a fixed bed reactor. The specific surface area and pore structure of different biomass chars were measured by nitrogen adsorption-desorption analysis instrument at 77K. The effects of biomass type, pyrolysis temperature, heating rate, activation temperature and concentration of SO{sub 2}, NO on the adsorption efficiency of SO{sub 2}, NO were analyzed. The results indicated that the steam activation has significant effects on the specific surface area, total pore volume and micro-morphology of biomass chars by improving the internal structure. The adsorption efficiency of SO{sub 2}, NO increased with the decreasing of SO{sub 2}, NO concentration in the experimental range. The optimal condition of char preparation (873K, fast pyrolysis) and steam activation (1,073K) was proposed based on the adsorption efficiency and adsorption volume of SO{sub 2}, NO. It builds a theoretical basis for industrial applications of biomass.

Evaluation of the Compressive Strength of Cement-Spent Resins Matrix Mixed with Bio char

International Nuclear Information System (INIS)

Zalina Laili; Muhamad Samudi Yasir; Zalina Laili; Mohd Abdul Wahab; Nur Azna Mahmud; Nurfazlina Zainal Abidin

2015-01-01

The evaluation of compressive strength of cement-spent resins matrix mixed with bio char was investigated. In this study, bio char with different percentage (5 %, 8 %, 11 % 14 % and 18 %) was used as alternative admixture material for cement solidification of spent resins. Some properties of the physical and chemical of spent resins and bio char were also investigated. The performance of cemented spent resins with the addition of bio char was evaluated based on their compressive strength and the water resistance test. The compressive strength was evaluated at three different curing periods of 7, 14 and 28 days, while 4 weeks of immersion in distilled water was chosen for water resistance test. The result indicated that the compressive strength at 7, 14 and 28 days of curing periods were above the minimum criterion for example > 3.45 MPa of acceptable level for cemented waste form. Statistical analysis showed that there was no significant relationship between the compressive strength of the specimen and the percentage of bio char content. Result from the water resistance test showed that only one specimen that contained of 5 % of bio char failed the water resistance test due to the high of spent resins/ bio char ratio. The compressive strength of cement solidified spent resins was found increased after the water resistance test indicating further hydration occurred after immersed in water. The results of this study also suggest that the specimen with 8 %, 11 %, 14 % and 18 % of bio char content were resistance in water and suitable for the leaching study of radionuclides from cement-bio char-spent resins matrix. (author)

Effects of pressure on morphology and structure of bio-char from pressurized entrained-flow pyrolysis of microalgae

Directory of Open Access Journals (Sweden)

Kristina Maliutina

2018-06-01

Full Text Available The present dataset describes the entrained-flow pyrolysis of Microalgae Chlorella vulgaris and the results obtained during bio-char characterization. The dataset includes a brief explanation of the experimental procedure, experimental conditions and the influence of pyrolysis conditions on bio-chars morphology and carbon structure. The data show an increase in sphericity and surface smoothness of bio-chars at higher pressures and temperatures. Data confirmed that the swelling ratio of bio-chars increased with pressure up to 2.0 MPa. Consequently, changes in carbon structure of bio-chars were investigated using Raman spectroscopy. The data showed the increase in carbon order of chars at elevated pressures. Changes in the chemical structure of bio-char as a function of pyrolysis conditions were investigated using FTIR analysis. Keywords: Microalgae, Bio-char, Particle swelling, Pressurized pyrolysis

NMR studies on the chemical alteration of soil organic matter precursors during controlled charring

Science.gov (United States)

Knicker, Heike

2010-05-01

Beside the production of volatiles, vegetation fire transforms various amounts of labile organic components into recalcitrant dark colored and highly aromatic structures. They are incorporated into soils and are assumed to represent an important sink within the global carbon cycle. In order to elucidate the real importance of PyOM as a C-sink, a good understanding of its chemistry is crucial. Although several 'Black Carbon' (BC) models are reported, a commonly accepted view of the chemistry involved in its formation is still missing. Its biogeochemical recalcitrance is commonly associated with a highly condensed aromatic structure. However, recent studies indicated that this view may be oversimplified for PyOM derived from vegetation fire. In order to bring some more light on the structural properties of PyOM produced during vegetation fire, charred plant residues and model chars derived from typical plant macromolecules (casein, cellulose, lignin and condensed tannins) were subjected to controlled charring under oxic conditions (350°C and 450°C) and then characterized by nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Subsequently, the chemical features of the PyOM were related to its chemical recalcitrance as determined by chemical oxidation with acid potassium dichromate. Charring cellulose (350°C, 8 min) yielded in a low C-recovery (11%). Treating casein in the same way resulted in a survival of 62% of its C and 46% of its N. Comparable high C-recoveries are reported for lignin. After charring Lolium perenne, 34% of its N and C were recovered. NMR-spectroscopic studies revealed that for this sample most of the charred N and C occurred in pyrrole-type structures. Our studies further indicate that the aromatic skeleton of char accumulating after a vegetation fire must contain remains of the lignin backbone and considerable contributions of furans and anhydrosugars from thermally altered cellulose. Enhancing the temperature during the

The rates of production of CO and CO2 from the combustion of pulverized coal particles in a shock tube

NARCIS (Netherlands)

Commissaris, F.A.C.M.; Banine, V.Y.; Roekaerts, D.J.E.M.; Veefkind, A.

1998-01-01

This work presents some results of experiments on coal combustion in a shock tube, as well as a time-dependent model of the boundary layer of a single, burning char particle under similar conditions. The partial pressure of O2 in a shock tube was varied between 0 and 10 bar, with gas temperatures

Co-gasification of coal and biomass: Synergy, characterization and reactivity of the residual char.

Science.gov (United States)

Hu, Junhao; Shao, Jingai; Yang, Haiping; Lin, Guiying; Chen, Yingquan; Wang, Xianhua; Zhang, Wennan; Chen, Hanping

2017-11-01

The synergy effect between coal and biomass in their co-gasification was studied in a vertical fixed bed reactor, and the physic-chemical structural characteristics and gasification reactivity of the residual char obtained from co-gasification were also investigated. The results shows that, conversion of the residual char and tar into gas is enhanced due to the synergy effect between coal and biomass. The physical structure of residual char shows more pore on coal char when more biomass is added in the co-gasification. The migration of inorganic elements between coal and biomass was found, the formation and competitive role of K 2 SiO 3 , KAlSiO 4 , and Ca 3 Al 2 (SiO 4 ) 3 is a mechanism behind the synergy. The graphization degree is enhanced but size of graphite crystallite in the residual char decreases with biomass blending ratio increasing. TGA results strongly suggest the big difference in the reactivity of chars derived from coal and biomass in spite of influence from co-gasification. Copyright © 2017 Elsevier Ltd. All rights reserved.

Demineralisation of a semianthracite char with molten salts/HCl

International Nuclear Information System (INIS)

Alfaro-Dominguez, M.; Sanchez Bajo, F.

2006-01-01

The effects of chemical heat treatments of a semianthracite char (AC) on the composition of the mineral fraction of the material are investigated. The starting char was first treated with a mixture of LiCl/KCl or LiCl/KCl/CaO at 743, 873 or 1173 K and the products obtained were then washed thoroughly with distilled water. A small fraction of these samples were treated with 10 -3 M HCl solution. The composition changes were studied by X-ray diffraction. The predominant mineral components initially present in the starting char are quartz, mullite, muscovite and/or kaolinite and oldhamite. The treatments of AC resulted in significant changes in the mineral fraction of the material, in particular when LiCl/KCl/CaO was used. In this case, spurrite, γ-calcium orthosilicate and gehlenite were formed, which were eliminated by treatment with 10 -3 M HCl solution

Demineralisation of a semianthracite char with molten salts/HCl

Energy Technology Data Exchange (ETDEWEB)

Alfaro-Dominguez, M. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Avda de Elvas s/n, 06071 Badajoz (Spain)]. E-mail: malfaro@unex.es; Sanchez Bajo, F. [Departamento de Electronica e Ingenieria Electromecanica, Escuela de Ingenierias Industriales, Universidad de Extremadura, Avda de Elvas s/n, 06071 Badajoz (Spain)

2006-06-30

The effects of chemical heat treatments of a semianthracite char (AC) on the composition of the mineral fraction of the material are investigated. The starting char was first treated with a mixture of LiCl/KCl or LiCl/KCl/CaO at 743, 873 or 1173 K and the products obtained were then washed thoroughly with distilled water. A small fraction of these samples were treated with 10{sup -3} M HCl solution. The composition changes were studied by X-ray diffraction. The predominant mineral components initially present in the starting char are quartz, mullite, muscovite and/or kaolinite and oldhamite. The treatments of AC resulted in significant changes in the mineral fraction of the material, in particular when LiCl/KCl/CaO was used. In this case, spurrite, {gamma}-calcium orthosilicate and gehlenite were formed, which were eliminated by treatment with 10{sup -3} M HCl solution.

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).

History, Violence and Poetics: Saint-John Perse and René Char

Directory of Open Access Journals (Sweden)

Nathan Bracher

1991-06-01

Full Text Available This essay explores the parallel yet opposite stances taken both personally and textually by Perse and Char with respect to drama of World War II. While Perse remained disdainfully aloof from public affairs after the defeat and proclaimed in his poetry his solidarity with all humanity, Char explicitly linked his writing to events, yet sought to create a human space removed from history's upheavals. Striving to transcend the vicissitudes of individual existence, Perse celebrates an epic vision of history that overlooks and even condones its violence. Focusing on the inconsistent, fragmentary nature of existence, Char prevents us from having any teleological delusions concerning war.

A Thermogravimetric Study of the Behaviour of Biomass Blends During Combustion

Directory of Open Access Journals (Sweden)

Ivo Jiříček

2012-01-01

Full Text Available The ignition and combustion behavior of biomass and biomass blends under typical heating conditions were investigated. Thermogravimetric analyses were performed on stalk and woody biomass, alone and blended with various additive weight ratios. The combustion process was enhanced by adding oxygen to the primary air. This led to shorter devolatilization/pyrolysis and char burnout stages, which both took place at lower temperatures than in air alone. The results of the ignition study of stalk biomass show a decrease in ignition temperature as the particle size decreases. This indicates homogeneous ignition, where the volatiles burn in the gas phase, preventing oxygen from reaching the particle surface.The behavior of biomass fuels in the burning process was analyzed, and the effects of heat production and additive type were investigated. Mixing with additives is a method for modifying biofuel and obtaining a more continuous heat release process. Differential scanning calorimetric-thermogravimetric (DSC-TGA analysis revealed that when the additive is added to biomass, the volatilization rate is modified, the heat release is affected, and the combustion residue is reduced at the same final combustion temperature.

Numerical investigation for combustion characteristics of vacuum residue (VR) in a test furnace

International Nuclear Information System (INIS)

Sreedhara, S.; Huh, Kang Y.; Park, Hoyoung

2007-01-01

It has become inevitable to search for alternative fuels due to current worldwide energy crisis. In this paper combustion characteristics of vacuum residue (VR) is investigated numerically against experimental data in typical operating conditions of a furnace. Heat release reaction is modeled as sequential steps of devolatilization, simplified gas phase reaction and char oxidation as for pulverized coal. Thermal and fuel NO are predicted by the conditional moment closure (CMC) method for estimation of elementary reaction rates. It turns out that Sauter mean diameter (SMD) of VR droplets is a crucial parameter for better combustion efficiency and lower NO. Reasonable agreement is achieved for spatial distributions of major species, temperature and NO for all test cases with different fuel and steam flow rates

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...

The effect of 150μm expandable graphite on char expansion of intumescent fire retardant coating

International Nuclear Information System (INIS)

Ullah, Sami; Shariff, A. M.; Bustam, M. A.; Ahmad, Faiz

2014-01-01

Intumescent is defined as the swelling of certain substances to insulate the underlying substrate when they are heated. In this research work the effect of 150μm expandable graphite (EG) was studied on char expansion, char morphology and char composition of intumescent coating formulations (ICFs). To study the expansion and thermal properties of the coating, nine different formulations were prepared. The coatings were tested at 500 °C for one hour and physically were found very stable and well bound with the steel substrate. The morphology was studied by Scanning Electron Microscopy (SEM). The char composition was analysed by X-ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. EG above than 10.8wt% expands the char abruptly with uniform network structure and affect the outer surface of the char

The effect of 150μm expandable graphite on char expansion of intumescent fire retardant coating

Energy Technology Data Exchange (ETDEWEB)

Ullah, Sami, E-mail: samichemist1@gmail.com; Shariff, A. M., E-mail: azmish@petronas.com.my, E-mail: azmibustam@petronas.com.my; Bustam, M. A., E-mail: azmish@petronas.com.my, E-mail: azmibustam@petronas.com.my [Research Center for Carbon Dioxide Capture, Department of Chemical Engineering, Universiti Techologi PETRONAS, Bandar Sri Iskandar, Tronoh 31750 Perak (Malaysia); Ahmad, Faiz, E-mail: faizahmadster@gmail.com [Department of Mechanical Engineering, Universiti Techologi PETRONAS, Bandar Sri Iskandar, Tronoh 31750 Perak (Malaysia)

2014-10-24

Intumescent is defined as the swelling of certain substances to insulate the underlying substrate when they are heated. In this research work the effect of 150μm expandable graphite (EG) was studied on char expansion, char morphology and char composition of intumescent coating formulations (ICFs). To study the expansion and thermal properties of the coating, nine different formulations were prepared. The coatings were tested at 500 °C for one hour and physically were found very stable and well bound with the steel substrate. The morphology was studied by Scanning Electron Microscopy (SEM). The char composition was analysed by X-ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. EG above than 10.8wt% expands the char abruptly with uniform network structure and affect the outer surface of the char.

Production of activated carbon from TCR char

Science.gov (United States)

Stenzel, Fabian; Heberlein, Markus; Klinner, Tobias; Hornung, Andreas

2016-04-01

The utilization of char for adsorptive purposes is known since the 18th century. At that time the char was made of wood or bones and used for decoloration of fluids. In the 20th century the production of activated carbon in an industrial scale was started. The today's raw materials for activated carbon production are hard coal, peat, wood or coconut shells. All these materials entail costs especially the latter. Thus, the utilization of carbon rich residues (biomass) is an interesting economic opportunity because it is available for no costs or even can create income. The char is produced by thermo-catalytic reforming (TCR®). This process is a combination of an intermediate pyrolysis and subsequently a reforming step. During the pyrolysis step the material is decomposed in a vapor and a solid carbon enriched phase. In the second step the vapor and the solid phase get in an intensive contact and the quality of both materials is improved via the reforming process. Subsequently, the condensables are precipitated from the vapor phase and a permanent gas as well as oil is obtained. Both are suitable for heat and power production which is a clear advantage of the TCR® process. The obtained biochar from the TCR® process has special properties. This material has a very low hydrogen and oxygen content. Its stability is comparable to hard coal or anthracite. Therefore it consists almost only of carbon and ash. The latter depends from input material. Furthermore the surface structure and area can be influenced during the reforming step. Depending from temperature and residence time the number of micro pores and the surface area can be increased. Preliminary investigations with methylene blue solution have shown that a TCR® char made of digestate from anaerobic digestion has adsorptive properties. The decoloration of the solution was achieved. A further influencing factor of the adsorption performance is the particle size. Based on the results of the preliminary tests a

Ultrasonic Characterisation of Epoxy Resin/Polyethylene Terephthalate (PET Char Powder Composites

Directory of Open Access Journals (Sweden)

Imran ORAL

2016-11-01

Full Text Available This study is carried out in order to determine the elastic properties of the Epoxy Resin (ER / Polyethylene terephthalate (PET Char Powder Composites by ultrasonic wave velocity measurement method. Plastic waste was recycled as raw material for the preparation of epoxy composite materials. The supplied chars were mixed with epoxy resin matrix at weight percentages of 10 %, 20 % and 30 % for preparing ER/PET Char Powder (PCP composites. The effect of PET char powder on the elastic properties of ER/PCP composites were investigated by ultrasonic pulse-echo method. According to the obtained results, the composition ratio of 80:20 is the most appropriate composition ratio, which gave the highest elastic constants values for ER/PCP composites. On the other hand, the best electrical conductivity value was obtained for 70:30 composition ratio. It was observed that ultrasonic shear wave velocity correlated more perfectly than any other parameters with hardness.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12190

Endotoxin Removal from Water Using Heterogenus Catalytic Ozonation by Bone Char

Directory of Open Access Journals (Sweden)

Abas Rezaee

2011-10-01

Full Text Available The endotoxin is one of pollutants with lipopolysaccharide structure which release from gram negative bacteria and cyanobacters. The aim of this study was removal of endotoxin from water using catalytic ozonation by bone char. The endotoxin for experiments have extracted from Escherichia coli bacterium cell wall by Stefan and Jan method. Chromogenic limulus ambusite lysate method in 405-410 nm wave length was used for analysing of endotoxin. The ozone have analysed by potassium iodine method. Results: Results of the research shown endotoxin removal rates using heterogenous catalytic ozonation were 6.0 Eu/ml.min and 0.5 Eu/ml.min for grey bone char and white bone char, respectively. The efficency of the process was found eighty percent. Primary concentration of basic compounds had no effect on endotoxin removal rate. Therefore, endotoxin removal kinetic of reaction is a zero order reaction. This study revealed that ozonation process using bone char is more efficient than other proposed methods such as ozonation or chlorination and can be used successfully for endotoxin removal from water as a efficient method.

Preoxidation and Activation of the Lignin Char: Carbonization and Oxidation Procedures

Directory of Open Access Journals (Sweden)

Saloua Sebbahi

2014-01-01

Full Text Available A comprehensive process of pretreatment and oxidation of lignin char was developed to optimize the production of activated carbon. The lignin char was obtained by carbonization of lignin under nitrogen at 600°C for 2 hours. The optimum time and temperature used to oxidize the char without destruction were, respectively, 6 hours and 245°C. The oxygen improves the reactivity of the sample in CO2 and evolved the sample of a thermoplastic behaviour to a thermosetting behaviour. The oxygenation in air of the lignin char does not change the mode of deformation acquired by the material during the carbonization. The preoxidized coal reacts more than the nonoxidized coal during the CO2 activation, whereas the reduction in volume in the first case is smaller than in the second. The preoxidized and then activated carbon shows the formation and the development of microporosity at the expense of macroporosity. This microstructure is one of the main characteristics of activated carbon, which can be used as adsorbent for different pollutants.

Influence of pressure on pyrolysis of black liquor: 2. Char yields and component release.

Science.gov (United States)

Whitty, Kevin; Kullberg, Mika; Sorvari, Vesa; Backman, Rainer; Hupa, Mikko

2008-02-01

This is the second in a series of papers concerning the behavior of black liquor during pyrolysis at elevated pressures. Two industrial black liquors were pyrolyzed under pressurized conditions in two laboratory-scale devices, a pressurized single-particle reactor and a pressurized grid heater. Temperatures ranging between 650 and 1100 degrees C and pressures in the range 1-20 bar were studied. Char yields were calculated and based on analysis of some of the chars the fate of carbon, sodium, potassium and sulfur was determined as a function of pyrolysis pressure. At temperatures below 800 degrees C little variation in char yield was observed at different pressures. At higher temperatures char yield increased with pressure due to slower decomposition of sodium carbonate. For the same reason, sodium release decreased with pressure. Sulfur release, however, increased with pressure primarily because there was less opportunity for its capture in the less-swollen chars.

Adsorption of Pb(II by Activated Pyrolytic Char from Used Tire

Directory of Open Access Journals (Sweden)

Lu Ping

2016-01-01

Full Text Available As a renewable resource, the pyrolytic char derived from used tire has promising adsorption capacities owing to its similar structure and properties with active carbon. The purification and activation of the pyrolytic char from used tire, as well as the application of this material in the adsorption of Pb(II in water is conducted. The influences on the adsorption capacity by temperature and pH value are investigated and discussed; the adsorption thermodynamics and kinetics are also studied. The results show that the pyrolytic char from used tire has remarkable adsorption capacity for Pb(II, and the adsorption is an endothermic process complying with the Langmuir isotherm. The adsorption kinetics is a pseudo second-order reaction.

Characterization of Oxy-combustion Impacts in Existing Coal-fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Bradley Adams; Andrew Fry; Constance Senior; Hong Shim; Huafeng Wang; Jost Wendt; Christopher Shaddix

2009-06-30

This report summarizes Year 1 results of a research program designed to use multi-scale experimental studies and fundamental theoretical models to characterize and predict the impacts of retrofit of existing coal-fired utility boilers for oxy-combustion. Through the course of Year 1 activities, great progress was made toward understanding the issues associated with oxy-combustion retrofit of coal-fired boilers. All four Year 1 milestones and objectives have been, or will be, completed on schedule and within budget. Progress in the four milestone areas may be summarized as follows: • University of Utah has performed size segregated ash composition measurements in the Oxy-Fuel Combustor (OFC). These experiments indicate that oxy-combustion retrofit may impact ash aerosol mineral matter composition. Both flame temperature and flue gas composition have been observed to influence the concentration of calcium, magnesium and iron in the fine particulate. This could in turn impact boiler fouling and slagging. • Sandia National Labs has shown that char oxidation rate is dependent on particle size (for sizes between 60 and 100 microns) by performing fundamental simulations of reacting char particles. These predictions will be verified by making time-resolved optical measurements of char particle temperature, velocity and size in bench-scale experiments before the end of Year 1. • REI and Siemens have completed the design of an oxy-research burner that will be mounted on University of Utah’s pilot-scale furnace, the L1500. This burner will accommodate a wide range of O2, FGR and mixing strategies under conditions relevant for utility boiler operation. Through CFD modeling of the different burner designs, it was determined that the key factor influencing flame stabilization location is particle heat-up rate. The new oxy-research burner and associated equipment is scheduled for delivery before the end of Year 1. • REI has completed a literature survey of slagging and

Modelling of NO formation in the combustion of coal blends

Energy Technology Data Exchange (ETDEWEB)

Arenillas, A.; Backreedy, R.I.; Jones, J.M.; Pis, J.J.; Pourkashanian, M.; Rubiera, F.; Williams, A. [CSIC, Instituto Nacional del Carbon, Oviedo (Spain)

2002-03-01

Coal blending is becoming of increasing importance in power stations firing pulverised coal as a result of increasing competition, stricter emission legislation and is an attractive way of improving plant economic and combustion performance. Presently, the two general methods used by power station operators to assess or predict the performance of an unknown coal blend to be fired in power station boilers are by the use of experimental large scale rig tests or correlation indices derived from experience of firing other coal blends in the power station environment. The first is expensive and the second is of doubtful accuracy in some cases. This paper evaluates the application of mathematical modelling of the combustion of a series of binary coal blends in the test situation of a drop tube reactor to predict the NO emissions and degree of char burnout. Its applicability to low NOx burners used in power stations is discussed and it is concluded that present mathematical coal combustion models are not developed sufficiently to enable an adequate description of the binary blends and the physical and chemical processes, which may include interactions, during combustion of the blend. This means that accurate predictions cannot be made. 20 refs., 4 figs., 5 tabs.

The identification of unusual microscopic features in coal and their derived chars: Influence on coal fluidized bed combustion

Energy Technology Data Exchange (ETDEWEB)

Valentim, B. [Centro de Geologia da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Lemos de Sousa, M.J. [Centro de Geologia da Universidade do Porto, Praca de Gomes Teixeira, 4099-002 Porto (Portugal); Abelha, P.; Boavida, D.; Gulyurtlu, I. [Departamento de Engenharia Energetica e Controlo Ambiental (DEECA), Instituto Nacional de Engenharia, Tecnologia e Inovacao (INETI), Estrada do Paco do Lumiar, 22, Edif. J, 1649-038, Lisboa (Portugal)

2006-06-06

During the petrographic study of seven feed coals from different origins, it was found that these coals presented microfeatures such as: material size, shape, weathering, thermally affected particles and contamination. After devolatilization under fluidized bed conditions, some chars presented the consequences of the above mentioned microfeatures, i.e., unreacted coal, unswelled particles, coatings and microstratification. Since the amounts of the microfeatures observed were low (less than 1%), the present study is essentially observational/descriptional. However, it seems very likely, from the observations that were made, that the occurrence of one or more of these microfeatures in coal, depending on their kind and abundance, may have significant effect on the coal devolatilization. (author)

Mixed waste treatment using the ChemChar thermolytic detoxification technique

Energy Technology Data Exchange (ETDEWEB)

Kuchynka, D.

1995-12-31

The diversity of mixed waste matrices contained at Department of Energy sites that require treatment preclude a single, universal treatment technology capable of handling sludges, solids, heterogeneous debris, aqueous and organic liquids and soils. Versatility of the treatment technology, volume reduction and containment of the radioactive component of the mixed waste streams are three criteria to be considered when evaluating potential treatment technologies. The ChemChar thermolytic detoxification process being developed under this R and D contract is a thermal, chemically reductive technology that converts the organic portion of a mixed waste stream to an energy-rich synthesis gas while simultaneously absorbing volatile inorganic species (metals and acid gases) on a macroporous, carbon-based char. The latter is mixed with the waste stream prior to entering the reactor. Substoichiometric amounts of oxidant are fed into the top portion of the cylindrical reactor generating a thin, radial thermochemical reaction zone. This zone generates all the necessary heat to promote the highly endothermic reduction of the organic components in the waste in the lower portion of the reactor, producing, principally, hydrogen and carbon monoxide. The solid by-product is a regenerated carbon char that, depending on the inorganic loading, is capable for reuse. The in situ scrubbing of contaminants by the char within the reactor coupled with a char filter for final polishing produce an exceptionally clean synthesis gas effluent suitable for on-site generation of heat, steam or electricity. Despite the elevated temperatures in the thermochemical reaction zone, the reductive nature of the process precludes formation of nitrogen oxides and halogenated organic compound by-products.

Mixed waste treatment using the ChemChar thermolytic detoxification technique

International Nuclear Information System (INIS)

Kuchynka, D.

1995-01-01

The diversity of mixed waste matrices contained at Department of Energy sites that require treatment preclude a single, universal treatment technology capable of handling sludges, solids, heterogeneous debris, aqueous and organic liquids and soils. Versatility of the treatment technology, volume reduction and containment of the radioactive component of the mixed waste streams are three criteria to be considered when evaluating potential treatment technologies. The ChemChar thermolytic detoxification process being developed under this R and D contract is a thermal, chemically reductive technology that converts the organic portion of a mixed waste stream to an energy-rich synthesis gas while simultaneously absorbing volatile inorganic species (metals and acid gases) on a macroporous, carbon-based char. The latter is mixed with the waste stream prior to entering the reactor. Substoichiometric amounts of oxidant are fed into the top portion of the cylindrical reactor generating a thin, radial thermochemical reaction zone. This zone generates all the necessary heat to promote the highly endothermic reduction of the organic components in the waste in the lower portion of the reactor, producing, principally, hydrogen and carbon monoxide. The solid by-product is a regenerated carbon char that, depending on the inorganic loading, is capable for reuse. The in situ scrubbing of contaminants by the char within the reactor coupled with a char filter for final polishing produce an exceptionally clean synthesis gas effluent suitable for on-site generation of heat, steam or electricity. Despite the elevated temperatures in the thermochemical reaction zone, the reductive nature of the process precludes formation of nitrogen oxides and halogenated organic compound by-products

Feasibility of mercury removal from simulated flue gas by activated chars made from poultry manures.

Science.gov (United States)

Klasson, K Thomas; Lima, Isabel M; Boihem, Larry L; Wartelle, Lynda H

2010-12-01

Increased emphasis on reduction of mercury emissions from coal fired electric power plants has resulted in environmental regulations that may in the future require application of activated carbons as mercury sorbents for mercury removal. At the same time, the quantity of poultry manure generated each year is large and technologies that take advantage of the material should be explored. The purpose of the work was to obtain preliminary data to investigate if activated chars made from different poultry manures could adsorb mercury from simulated flue gas. In laboratory experiments, activated chars made from chicken cake and litter removed mercury from the gas as well as a commercial alternative. It was also found that acid-washing these chars after activation may improve pore structure but does not influence the mercury removal efficiency. Activated chars were also made from turkey cake and litter. These raw materials produced activated chars with similar pore structure as those made from chicken manure, but they did not adsorb mercury as well. Acid-washing the turkey manure-based chars improved their performance, but this step would add to the cost of production. Preliminary evaluations suggest that unwashed activated chars may cost as little as $0.95/kg to produce. Published by Elsevier Ltd.

Integration of CFD codes and advanced combustion models for quantitative burnout determination

Energy Technology Data Exchange (ETDEWEB)

Javier Pallares; Inmaculada Arauzo; Alan Williams [University of Zaragoza, Zaragoza (Spain). Centre of Research for Energy Resources and Consumption (CIRCE)

2007-10-15

CFD codes and advanced kinetics combustion models are extensively used to predict coal burnout in large utility boilers. Modelling approaches based on CFD codes can accurately solve the fluid dynamics equations involved in the problem but this is usually achieved by including simple combustion models. On the other hand, advanced kinetics combustion models can give a detailed description of the coal combustion behaviour by using a simplified description of the flow field, this usually being obtained from a zone-method approach. Both approximations describe correctly general trends on coal burnout, but fail to predict quantitative values. In this paper a new methodology which takes advantage of both approximations is described. In the first instance CFD solutions were obtained of the combustion conditions in the furnace in the Lamarmora power plant (ASM Brescia, Italy) for a number of different conditions and for three coals. Then, these furnace conditions were used as inputs for a more detailed chemical combustion model to predict coal burnout. In this, devolatilization was modelled using a commercial macromolecular network pyrolysis model (FG-DVC). For char oxidation an intrinsic reactivity approach including thermal annealing, ash inhibition and maceral effects, was used. Results from the simulations were compared against plant experimental values, showing a reasonable agreement in trends and quantitative values. 28 refs., 4 figs., 4 tabs.

Abundant and stable char residues in soils: implications for soil fertility and carbon sequestration.

Science.gov (United States)

Mao, J-D; Johnson, R L; Lehmann, J; Olk, D C; Neves, E G; Thompson, M L; Schmidt-Rohr, K

2012-09-04

Large-scale soil application of biochar may enhance soil fertility, increasing crop production for the growing human population, while also sequestering atmospheric carbon. But reaching these beneficial outcomes requires an understanding of the relationships among biochar's structure, stability, and contribution to soil fertility. Using quantitative (13)C nuclear magnetic resonance (NMR) spectroscopy, we show that Terra Preta soils (fertile anthropogenic dark earths in Amazonia that were enriched with char >800 years ago) consist predominantly of char residues composed of ~6 fused aromatic rings substituted by COO(-) groups that significantly increase the soils' cation-exchange capacity and thus the retention of plant nutrients. We also show that highly productive, grassland-derived soils in the U.S. (Mollisols) contain char (generated by presettlement fires) that is structurally comparable to char in the Terra Preta soils and much more abundant than previously thought (~40-50% of organic C). Our findings indicate that these oxidized char residues represent a particularly stable, abundant, and fertility-enhancing form of soil organic matter.

Mixed waste treatment using the ChemChar thermolytic detoxification technique

Energy Technology Data Exchange (ETDEWEB)

Kuchynka, D. [Mirage Systems, Sunnyvale, CA (United States)

1995-10-01

The diversity of mixed waste matrices contained at Department of Energy sites that require treatment preclude a single, universal treatment technology capable of handling sludges, solids, heterogeneous debris, aqueous and organic liquids and soils. This report describes the ChemChar thermolytic detoxification process. The process is a thermal, chemically reductive technology that converts the organic portion of mixed wastes to a synthesis gas, while simultaneously absorbing volatile inorganics on a carbon-based char.

Influence of post-treatment strategies on the properties of activated chars from broiler manure.

Science.gov (United States)

Lima, Isabel M; Boykin, Debbie L; Thomas Klasson, K; Uchimiya, Minori

2014-01-01

There are a myriad of carbonaceous precursors that can be used advantageously to produce activated carbons or chars, due to their low cost, availability and intrinsic properties. Because of the nature of the raw material, production of granular activated chars from broiler manure results in a significant ash fraction. This study was conducted to determine the influence of several pre- and post-treatment strategies in various physicochemical and adsorptive properties of the resulting activated chars. Pelletized samples of broiler litter and cake were pyrolyzed at 700 °C for 1h followed by a 45 min steam activation at 800 °C at different water flow rates from 1 to 5 mL min(-1). For each activation strategy, samples were either water-rinsed or acid-washed and rinsed or used as is (no acid wash/rinse). Activated char's physicochemical and adsorptive properties towards copper ions were selectively affected by both pre- and post-treatments. Percent ash reduction after either rinsing or acid washing ranged from 1.1 to 15.1% but washed activated chars were still alkaline with pH ranging from 8.4 to 9.1. Acid washing or water rinsing had no significant effect in the ability of the activated char to adsorb copper ions, however it significantly affected surface area, pH, ash content and carbon content. Instead, manure type (litter versus cake) and the activation water flow rate were determining factors in copper ion adsorption which ranged from 38 mg g(-1) to 104 mg g(-1) of activated char. Moreover, strong positive correlations were found between copper uptake and concentration of certain elements in the activated char such as phosphorous, sulfur, calcium and sodium. Rinsing could suffice as a post treatment strategy for ash reduction since no significant differences in the carbon properties were observed between rinsed and acid wash treatments. Published by Elsevier Ltd.

Two-step microalgal biodiesel production using acidic catalyst generated from pyrolysis-derived bio-char

International Nuclear Information System (INIS)

Dong, Tao; Gao, Difeng; Miao, Chao; Yu, Xiaochen; Degan, Charles; Garcia-Pérez, Manuel; Rasco, Barbara; Sablani, Shyam S.; Chen, Shulin

2015-01-01

Highlights: • Highly active catalyst was prepared using bio-char co-produced in Auger pyrolysis. • Catalyst inhibitors in crude oil were effectively removed by a practical refinery process. • Free fatty acids (FFA) content in refined microalgal oil was reduced to less than 0.5%. • A total fatty acid methyl ester (FAME) yield of 99% was obtained via a two-step process. • The inexpensive bio-char catalyst is superior to Amberlyst-15 in pre-esterification. - Abstract: An efficient process for biodiesel production from fast-refined microalgal oil was demonstrated. A low cost catalyst prepared from pyrolysis-derived bio-char, was applied in pre-esterification to reduce free fatty acid (FFA) content. Results showed that the bio-char catalyst was highly active in esterification; however, the performance of the catalyst significantly reduced when crude microalgal oil was used as feedstock. To solve the problem caused by catalyst-fouling, a fast and scalable crude oil refinery procedure was carried out to remove chlorophyll and phospholipids that might degrade the catalyst and the quality of biodiesel. The activity and reusability of bio-char catalyst were remarkably improved in the fast-refined oil. FFA content in the refined microalgal oil was reduced to less than 0.5% after pre-esterification. The bio-char catalyst could be reused for 10 cycles without dramatic loss in activity. The pre-esterification fits the first-order kinetic reaction with activation energy of 42.16 kJ/mol. The activity of bio-char catalyst was superior to commercial Amberlyst-15 under the same reaction condition. A total fatty acid methyl ester (FAME, namely biodiesel) yield of 99% was obtained following the second-step CaO-catalyzed transesterification. The cost-effective bio-char catalyst has great potential for biodiesel production using feedstocks having high FFA content.

WMU Power Generation Study Task 2.0 Corn Cob Co-Combustion Study: Final Report

Energy Technology Data Exchange (ETDEWEB)

Folkedahl, Bruce [Folkedahl Consulting, Inc., Willmar, MN (United States)

2009-12-01

Much attention has been focused on renewable energy use in large-scale utilities and very small scale distributed energy systems. However, there is little information available regarding renewable energy options for midscale municipal utilities. The Willmar Municipal Utilities Corn Cob-Coal Co-Combustion Project was initiated to investigate opportunities available for small to midscale municipal utilities to "go green". The overall goal of the Project was to understand the current renewable energy research and energy efficiency projects that are or have been implemented at both larger and smaller scale and determine the applicability to midscale municipal utilities. More specific objectives for Task 2.0 of this project were to determine the technical feasibility of co-combusting com cobs with coal in the existing WMU boiler, and to identify any regulatory issues that might need to be addressed if WMU were to obtain a significant portion of its heat from such co-combustion. This report addresses the issues as laid out in the study proposal. The study investigated the feasibility of and demonstrated the technical effectiveness of co-combusting corn cobs with coal in the Willmar Municipal Utilities stoker boiler steam generation power plant. The results of the WMU Co-Combustion Project will serve as a model for other midscale utilities who wish to use corn cobs to generate renewable electrical energy. As a result of the Co-Combustion Project, the WMU plans to upgrade their stoker boiler to accept whole corn cobs as well as other types of biomass, while still allowing the fuel delivery system to use 100% coal as needed. Benefits of co-combustion will include: energy security, reduced Hg and CO₂ air emissions, improved ash chemistry, potential future carbon credit sales, an immediate positive effect on the local economy, and positive attention focused on the WMU and the City of Willmar. The first step in the study was to complete a feasibility analysis. The

Predictive Method for Correct Identification of Archaeological Charred Grape Seeds: Support for Advances in Knowledge of Grape Domestication Process

Science.gov (United States)

Ucchesu, Mariano; Orrù, Martino; Grillo, Oscar; Venora, Gianfranco; Paglietti, Giacomo; Ardu, Andrea; Bacchetta, Gianluigi

2016-01-01

The identification of archaeological charred grape seeds is a difficult task due to the alteration of the morphological seeds shape. In archaeobotanical studies, for the correct discrimination between Vitis vinifera subsp. sylvestris and Vitis vinifera subsp. vinifera grape seeds it is very important to understand the history and origin of the domesticated grapevine. In this work, different carbonisation experiments were carried out using a hearth to reproduce the same burning conditions that occurred in archaeological contexts. In addition, several carbonisation trials on modern wild and cultivated grape seeds were performed using a muffle furnace. For comparison with archaeological materials, modern grape seed samples were obtained using seven different temperatures of carbonisation ranging between 180 and 340ºC for 120 min. Analysing the grape seed size and shape by computer vision techniques, and applying the stepwise linear discriminant analysis (LDA) method, discrimination of the wild from the cultivated charred grape seeds was possible. An overall correct classification of 93.3% was achieved. Applying the same statistical procedure to compare modern charred with archaeological grape seeds, found in Sardinia and dating back to the Early Bronze Age (2017–1751 2σ cal. BC), allowed 75.0% of the cases to be identified as wild grape. The proposed method proved to be a useful and effective procedure in identifying, with high accuracy, the charred grape seeds found in archaeological sites. Moreover, it may be considered valid support for advances in the knowledge and comprehension of viticulture adoption and the grape domestication process. The same methodology may also be successful when applied to other plant remains, and provide important information about the history of domesticated plants. PMID:26901361

Reactivity of chars prepared from the pyrolysis of a Victorian lignite under a wide range of conditions

Energy Technology Data Exchange (ETDEWEB)

Wu, H.; Mody, D.; Li, C.; Hayashi, J.; Chiba, T. [Monash University, Vic. (Australia). CRC for Clean Power from Lignite, Dept. of Chemical Engineering

2000-07-01

A Loy Yang lignite sample was pyrolysed under a wide range of experimental conditions using a wire-mesh reactor, a fluidised-bed reactor, a drop-tube reformer and a thermogravimetric analyser (TGA). The reactivity of these char samples in CO{sub 2} and air was measured in the TGA as well as in the fluidised-bed reactor. A sample prepared by the physical impregnation of NaCl into the lignite was also used in order to investigate the effect of NaCl in the lignite on the reactivity of the resulting char. Our experimental results indicate that, due to the volatilisation of a substantial fraction of Na in the lignite substrate during pyrolysis, the true catalytic activity of the Na in the lignite substrate should be evaluated by measuring the sodium content in the char after pyrolysis. The char reactivity measured in situ in the fluidised-bed reactor was compared with that of the same char measured separately in the TGA after re-heating the char sample to the same temperature as that in the fluidised-bed. It was found that the re-heating of the char in the TGA reduced the char reactivity.

Structural evolution of biomass char and its effect on the gasification rate

DEFF Research Database (Denmark)

Fatehi, Hesameddin; Bai, Xue Song

2017-01-01

The evolution of char porous structure can affect the conversion rate of the char by affecting the intra-particle transport, especially in the zone II conversion regime. A multi-pore model based on the capillary pore theory is developed to take into account different conversion rates for pores wi...

Role of oxygen-containing functional groups in forest fire-generated and pyrolytic chars for immobilization of copper and nickel.

Science.gov (United States)

Esfandbod, Maryam; Merritt, Christopher R; Rashti, Mehran Rezaei; Singh, Balwant; Boyd, Sue E; Srivastava, Prashant; Brown, Christopher L; Butler, Orpheus M; Kookana, Rai S; Chen, Chengrong

2017-01-01

Char as a carbon-rich material, can be produced under pyrolytic conditions, wildfires or prescribed burn offs for fire management. The objective of this study was to elucidate mechanistic interactions of copper (Cu 2+ ) and nickel (Ni 2+ ) with different chars produced by pyrolysis (green waste, GW; blue-Mallee, BM) and forest fires (fresh-burnt by prescribed fire, FC; aged char produced by wild fire, AC). The pyrolytic chars were more effective sorbents of Cu 2+ (∼11 times) and Ni 2+ (∼5 times) compared with the forest fire chars. Both cross-polarization (CPMAS-NMR) and Bloch decay (BDMAS-NMR) 13 C NMR spectroscopies showed that forest fire chars have higher woody components (aromatic functional groups) and lower polar groups (e.g. O-alkyl C) compared with the pyrolytic chars. The polarity index was greater in the pyrolytic chars (0.99-1.34) than in the fire-generated chars (0.98-1.15), while aromaticity was lower in the former than in the latter. Fourier transform infrared (FTIR) and Raman spectroscopies indicated the binding of carbonate and phosphate with both Cu 2+ and Ni 2+ in all chars, but with a greater extent in pyrolytic than forest fire-generated chars. These findings have demonstrated the key role of char's oxygen-containing functional groups in determining their sorption capacity for the Cu 2+ and Ni 2+ in contaminated lands. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pyrolysis conditions and ozone oxidation effects on ammonia adsorption in biomass generated chars.

Science.gov (United States)

Kastner, James R; Miller, Joby; Das, K C

2009-05-30

Ammonia adsorbents were generated via pyrolysis of biomass (peanut hulls and palm oil shells) over a range of temperatures and compared to a commercially available activated carbon (AC) and solid biomass residuals (wood and poultry litter fly ash). Dynamic ammonia adsorption studies (i.e., breakthrough curves) were performed using these adsorbents at 23 degrees C from 6 to 17 ppmv NH(3). Of the biomass chars, palm oil char generated at 500 degrees C had the highest NH(3) adsorption capacity (0.70 mg/g, 6 ppmv, 10% relative humidity (RH)), was similar to the AC, and contrasted to the other adsorbents (including the AC), the NH(3) adsorption capacity significantly increased if the relative humidity was increased (4 mg/g, 7 ppmv, 73% RH). Room temperature ozone treatment of the chars and activated carbon significantly increased the NH(3) adsorption capacity (10% RH); resultant adsorption capacity, q (mg/g) increased by approximately 2, 6, and 10 times for palm oil char, peanut hull char (pyrolysis only), and activated carbon, respectively. However, water vapor (73% RH at 23 degrees C) significantly reduced NH(3) adsorption capacity in the steam and ozone treated biomass, yet had no effect on the palm shell char generated at 500 degrees C. These results indicate the feasibility of using a low temperature (and thus low energy input) pyrolysis and activation process for the generation of NH(3) adsorbents from biomass residuals.

Carbon distribution in char residue from gasification of kraft black liquor

International Nuclear Information System (INIS)

Sricharoenchaikul, Viboon; Frederick, W.J.; Agrawal, Pradeep

2003-01-01

The char residue yields and the total carbon and carbonate content were measured for dry black liquor solids after pyrolysis or gasification in a laminar entrained-flow reactor. The experimental conditions were 700-1000 deg. C in N 2 ,CO 2 /N 2 or water vapor/N 2 at 1 bar total pressure, for residence times from 0.3 to 1.7 s. Fixed carbon yields, when measured at the same particle residence time, decreased with increasing reactor temperature. CO 2 and water vapor diminished the char carbon significantly at temperatures above 800 deg. C, compared with pyrolysis in N 2 . Water vapor oxidized the char carbon more rapidly than did CO 2 . At 1000 deg. C, the reactions of carbon with sulfate and carbonate became faster, resulting in a smaller difference between carbon conversion rates in the different gas environments. By the end of devolatilization, the amount of carbonate in the char had changed very little at 700-800 deg. C. After devolatilization, carbonate was formed more rapidly at higher temperatures. The presence of CO 2 or water vapor increased the formation of carbonate. In the presence of these gases, more carbonate was measured at all temperatures and residence times. The maximum carbonate measured in the char was 16% of the carbon in the black liquor solids, as compared to 4.4% in the original dry liquor solids. Under most conditions, the carbonate, as a fraction of carbon input, first increased to a constant, temperature-independent value and then decreased

Encapsulation of phase change materials using rice-husk-char

International Nuclear Information System (INIS)

Gondora, Wayne; Doudin, Khalid; Nowakowski, Daniel J.; Xiao, Bo; Ding, Yulong; Bridgwater, Tony; Yuan, Qingchun

2016-01-01

Highlights: • Rice-husk-char particles are successfully used in the encapsulation of phase change materials. • Carbon-based phase change microcapsules aim at using the high thermal conductivity of carbon materials. • Carbon from biomass can be used in low and intermediate heat harvest and storage. • Carbon in biomass is captured and to be used in improving energy efficiency. - Abstract: This paper explored a new approach to prepare phase change microcapsules using carbon-based particles via Pickering emulsions for energy storage applications. Rice-husk-char, a by-product in biofuel production, containing 53.58 wt% of carbon was used as a model carbon-based material to encapsulate hexadecane. As a model phase change material, hexadecane was emulsified in aqueous suspensions of rice-husk-char nanoparticles. Water soluble polymers poly(diallyldimethyl-ammonium chloride) and poly(sodium styrene sulfonate) were used to fix the rice-husk-char nanoparticles on the emulsion droplets through layer-by-layer assembly to enhance the structural stability of the microcapsules. The microcapsules formed are composed of a thin shell encompassing a large core consisting of hexadecane. Thermal gravimetrical and differential scanning calorimeter analyses showed the phase change enthalpy of 80.9 kJ kg"−"1 or 120.0 MJ m"−"3. Design criteria of phase change microcapsules and preparation considerations were discussed in terms of desired applications. This work demonstrated possible utilisations of biomass-originated carbon-based material for thermal energy recovery and storage applications, which can be a new route of carbon capture and utilisation.

Pyrolysis and oxy-fuel combustion characteristics and kinetics of petrochemical wastewater sludge using thermogravimetric analysis.

Science.gov (United States)

Chen, Jianbiao; Mu, Lin; Cai, Jingcheng; Yao, Pikai; Song, Xigeng; Yin, Hongchao; Li, Aimin

2015-12-01

The pyrolysis and oxy-fuel combustion characteristics of petrochemical wastewater sludge (PS) were studied in air (O2/N2) and oxy-fuel (O2/CO2) atmospheres using non-isothermal thermogravimetric analysis (TGA). Pyrolysis experiments showed that the weight loss profiles were almost similar up to 1050K in both N2 and CO2 atmospheres, while further weight loss took place in CO2 atmosphere at higher temperatures due to char-CO2 gasification. Compared with 20%O2/80%N2, the drying and devolatilization stage of PS were delayed in 20%O2/80%CO2 due to the differences in properties of the diluting gases. In oxy-fuel combustion experiments, with O2 concentration increasing, characteristic temperatures decreased, while characteristic combustion rates and combustion performance indexes increased. Kinetic analysis of PS decomposition under various atmospheres was performed using Coats-Redfern approach. The results indicated that, with O2 concentration increasing, the activation energies of Step 1 almost kept constant, while the values of subsequent three steps increased. Copyright © 2015 Elsevier Ltd. All rights reserved.

Combustion characteristics of Malaysian oil palm biomass, sub-bituminous coal and their respective blends via thermogravimetric analysis (TGA).

Science.gov (United States)

Idris, Siti Shawalliah; Rahman, Norazah Abd; Ismail, Khudzir

2012-11-01

The combustion characteristics of Malaysia oil palm biomass (palm kernel shell (PKS), palm mesocarp fibre (PMF) and empty fruit bunches (EFB)), sub-bituminous coal (Mukah Balingian) and coal/biomass blends via thermogravimetric analysis (TGA) were investigated. Six weight ratios of coal/biomass blends were prepared and oxidised under dynamic conditions from temperature 25 to 1100°C at four heating rates. The thermogravimetric analysis demonstrated that the EFB and PKS evolved additional peak besides drying, devolatilisation and char oxidation steps during combustion. Ignition and burn out temperatures of blends were improved in comparison to coal. No interactions were observed between the coal and biomass during combustion. The apparent activation energy during this process was evaluated using iso-conversional model free kinetics which resulted in highest activation energy during combustion of PKS followed by PMF, EFB and MB coal. Blending oil palm biomass with coal reduces the apparent activation energy value. Copyright © 2012 Elsevier Ltd. All rights reserved.

Comparison of high temperature chars of wheat straw and rice husk with respect to chemistry, morphology and reactivity

DEFF Research Database (Denmark)

Trubetskaya, Anna; Jensen, Peter Arendt; Jensen, Anker Degn

2016-01-01

Fast pyrolysis of wheat straw and rice husk was carried out in an entrained flow reactor at hightemperatures(1000e1500) C. The collected char was analyzed using X-ray diffractometry, N2-adsorption,scanning electron microscopy, particle size analysis with CAMSIZER XT, 29Si and 13C solid-statenucle......), which led to the formation of a glassy char shell, resulting in a preserved particlesize and shape of chars. The high alkali content in the wheat straw resulted in higher char reactivity,whereas the lower silicon content caused variations in the char shape from cylindrical to near...

Transformations of inorganic coal constituents in combustion systems. Volume 3, Appendices: Final report

Energy Technology Data Exchange (ETDEWEB)

Helble, J.J. [ed.; Srinivasachar, S.; Wilemski, G.; Boni, A.A. [PSI Technology Co., Andover, MA (United States); Kang, Shim-Gyoo; Sarofim, A.F.; Graham, K.A.; Beer, J.M. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Peterson, T.W.; Wendt, O.L.; Gallagher, N.B.; Bool, L. [Arizona Univ., Tucson, AZ (United States); Huggins, F.E.; Huffman, G.P.; Shah, N.; Shah, A. [Kentucky Univ., Lexington, KY (United States)

1992-11-01

This report contains the computer codes developed for the coal combustion project. In Subsection B.1 the FORTRAN code developed for the percolative fragmentation model (or the discrete model, since a char is expressed as a collection of discrete elements in a discrete space) is presented. In Subsection B.2 the code for the continuum model (thus named because mineral inclusions are distributed in a continuum space) is presented. A stereological model code developed to obtain the pore size distribution from a two-dimensional data is presented in Subsection B.3.

CO2 gasification of char from lignocellulosic garden waste: Experimental and kinetic study.

Science.gov (United States)

Gupta, Ankita; Thengane, Sonal K; Mahajani, Sanjay

2018-04-25

In this study, the dry leaves litter from jackfruit, raintree, mango and eucalyptus trees, lignin, and cellulose were characterized, pyrolysed, and evaluated for their char reactivity towards CO 2 gasification using TGA. The differences in char reactivity were attributed to the difference in char morphology and the varying inorganic contents. The mineral analysis of biomass ash showed the presence of alkali minerals some of which could act as catalysts. The adverse effect of high silica content was also evident through the experimental results. The kinetic parameters for gasification reaction were determined using three different reaction models. A modified random pore model was investigated to account for the influence of inorganic content. The effect of external catalyst on CO 2 gasification was also studied by adding potassium carbonate to biomass char and pellets. The results obtained from this study can be conveniently used in the design of a gasifier for lignocellulosic garden waste. Copyright © 2018 Elsevier Ltd. All rights reserved.

Experimental study of cyclone combustion of wood powder for gas turbine applications

Energy Technology Data Exchange (ETDEWEB)

Fredriksson, J; Kallner, P [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Energy Technology

1994-12-31

The objective of the present project is to study to what extent various elements in the ash, in particular Na and K, can be separated in the first stage of a two-stage combustor, with the first stage being a separation cyclone. Mass balances for the elements in the ash are determined from the fuel flow, the char collected from the cyclone bottom and particles in the combustor outlet gas. Experiments have been carried out at atmospheric pressure for wood powder feeding rates of 5-21 kg/h. The conditions in the cyclone have been kept fuel rich. The gas outlet temperature from this stage has been varied from 750 to 1150 deg C through control of the air/fuel ratio. Second stage combustion is achieved in a separate combustor. The results show that significant separation of Na and K is possible, and that the separation is improved when the cyclone temperature is kept low. At an outlet temperature of around 800 deg C about 60% of the input alkali is found in the char residue. At 1000 deg C, only 30% is separated. Mass balances show that about 80% of the ash elements in the fuel input are identified in char and fly ash. With 60% separation of Na and K the content of these elements in the gas would be less than 7 mg/kg gas for a turbine inlet temperature of 850 deg C. The total dust load would be 30-60 mg/kg gas. Ash sticking temperature tests on bottom char and fly ash show no ash sticking up to 1040 deg C. It is therefore concluded that the ash may pass through the turbine as solid particles and cause minimal deposits or corrosion. 15 refs

Experimental study of cyclone combustion of wood powder for gas turbine applications

Energy Technology Data Exchange (ETDEWEB)

Fredriksson, J.; Kallner, P. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Energy Technology

1993-12-31

The objective of the present project is to study to what extent various elements in the ash, in particular Na and K, can be separated in the first stage of a two-stage combustor, with the first stage being a separation cyclone. Mass balances for the elements in the ash are determined from the fuel flow, the char collected from the cyclone bottom and particles in the combustor outlet gas. Experiments have been carried out at atmospheric pressure for wood powder feeding rates of 5-21 kg/h. The conditions in the cyclone have been kept fuel rich. The gas outlet temperature from this stage has been varied from 750 to 1150 deg C through control of the air/fuel ratio. Second stage combustion is achieved in a separate combustor. The results show that significant separation of Na and K is possible, and that the separation is improved when the cyclone temperature is kept low. At an outlet temperature of around 800 deg C about 60% of the input alkali is found in the char residue. At 1000 deg C, only 30% is separated. Mass balances show that about 80% of the ash elements in the fuel input are identified in char and fly ash. With 60% separation of Na and K the content of these elements in the gas would be less than 7 mg/kg gas for a turbine inlet temperature of 850 deg C. The total dust load would be 30-60 mg/kg gas. Ash sticking temperature tests on bottom char and fly ash show no ash sticking up to 1040 deg C. It is therefore concluded that the ash may pass through the turbine as solid particles and cause minimal deposits or corrosion. 15 refs

Formation and emission of PM10 in combustion of biofuels. Final report

International Nuclear Information System (INIS)

Johansson, Linda; Tullin, Claes; Leckner, Bo

2004-02-01

.g. soot). Submicron particles (particles less than 1 μm) dominated the emission, both with respect to mass and number. Analyses with EDX (Electron Dispersive X-ray), ICP-MS (Inductively Coupled Plasma Mass-Spectrometry), and IC (Ion-Chromatography) showed that the main components in the submicron particles were potassium, sulphur, chlorine, and oxygen. TOF-SIMS (Time-of-flight Secondary Ion Mass Spectrometry) analysis showed that potassium-sulphate followed by potassium chloride were the most dominant substances among alkali -sulphates -chlorides, and -carbonates. For morphology, many spherical particles around 0.1 μm were found. In the second part of the project, the formation of particles during bio-fuel combustion is studied by first measurements on metal release during biofuel combustion. Results from the first part of the project have shown that the particle emission is dominated by inorganic particles at favourable combustion conditions, and the second part is therefore focused on inorganic particles, in which metals are a part. The release of metals is studied to investigate the possibilities to influence formation of combustion particles, and consequently the particle emission. To be able to perform as many tests as possible and to include wide variations in combustion conditions, the second part of the project is carried out using a laboratory reactor. To obtain a time-resolved signal of the release of metals, a large number of single pellets were fired in a laboratory reactor and chemically analysed afterwards using ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometry). The combustion lapse was interrupted after devolatisation, and after 25 %, 50 %, and 75 % of the char burnout. To obtain a time resolved signal of the emission of unburnt particulate matter a photoelectric aerosol sensor was used as a soot indicator. The results of the initial tests show that the main part of the metals was released during char combustion, but a certain metal

Thermogravimetric study on the influence of structural, textural and chemical properties of biomass chars on CO2 gasification reactivity

International Nuclear Information System (INIS)

Bouraoui, Zeineb; Jeguirim, Mejdi; Guizani, Chamseddine; Limousy, Lionel; Dupont, Capucine; Gadiou, Roger

2015-01-01

The present investigation aims to examine the influence of textural, structural and chemical properties of biomass chars on the CO 2 gasification rate. Various lignocellulosic biomass chars were prepared under the same conditions. Different analytical techniques were used to determine the char properties such as Scanning Electronic Microscopy, nitrogen adsorption manometry, Raman spectroscopy and X Ray Fluorescence. Gasification tests were carried out in a thermobalance under 20% CO 2 in nitrogen at 800 °C. Significant differences of the total average reactivity were observed with a factor of 2 between the prepared chars. Moreover, different behaviors of gasification rate profiles versus conversion were obtained. This difference of behavior appeared to be correlated with the biomass char properties. Hence, up to 70% of conversion, the gasification rate was shown to depend on the char external surface and the potassium content. At higher conversion ratio, a satisfactory correlation between the Catalytic Index and the average gasification rate was identified. The results highlight the importance of knowing both textural and structural properties and mineral contents of biomass chars to predict fuel reactivity during CO 2 gasification processes. Such behavior prediction is highly important in the gasifiers design for char conversion. - Highlights: • CO 2 gasification reactivity of various lignocellulosic chars were examined. • Chars properties affect strongly samples gasification behavior. • Initial gasification rate is affected by external surface, K content and D3/G ratio. • Gasification rate behavior depends on the Alkali index at high conversion

Synthesis and characterization of resorcinol–formaldehyde resin chars doped by zinc oxide

International Nuclear Information System (INIS)

Gun’ko, Vladimir M.; Bogatyrov, Viktor M.; Oranska, Olena I.; Urubkov, Iliya V.; Leboda, Roman; Charmas, Barbara; Skubiszewska-Zięba, Jadwiga

2014-01-01

Polycondensation polymerization of resorcinol–formaldehyde (RF) mixtures in water with addition of different amounts of zinc acetate and then carbonization of dried gels are studied to prepare ZnO doped chars. Zinc acetate as a catalyst of resorcinol–formaldehyde polycondensation affects structural features of the RF resin (RFR) and, therefore, the texture of chars prepared from Zn-doped RFR. The ZnO doped chars are characterized using thermogravimetry, low temperature nitrogen adsorption/desorption, Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM). At a relatively high content of zinc acetate (1 mol per 10–40 mol of resorcinol) in the reaction mixture, the formation of crystallites of ZnO (zincite) occurs in a shape of straight nanorods of 20–130 nm in diameter and 1–3 μm in length. At a small content of zinc acetate (1 mol per 100–500 mol of resorcinol), ZnO in composites is XRD amorphous and does not form individual particles. The ZnO doped chars are pure nanoporous at a minimal ZnO content and nano-mesoporous or nano-meso-macroporous at a higher ZnO content.

Removal of copper by oxygenated pyrolytic tire char: kinetics and mechanistic insights.

Science.gov (United States)

Quek, Augustine; Balasubramanian, Rajashekhar

2011-04-01

The kinetics of copper ion (Cu(II)) removal from aqueous solution by pyrolytic tire char was modeled using five different conventional models. A modification to these models was also developed through a modified equation that accounts for precipitation. Conventional first- and second-order reaction models did not fit the copper sorption kinetics well, indicating a lack of simple rate-order dependency on solute concentration. Instead, a reversible first-order rate reaction showed the best fit to the data, indicating a dependence on surface functional groups. Due to the varying solution pH during the sorption process, modified external and internal mass transfer models were employed. Results showed that the sorption of copper onto oxygenated chars was limited by external mass transfer and internal resistance with and without the modification. However, the modification of the sorption process produced very different results for unoxygenated chars, which showed neither internal nor external limitation to sorption. Instead, its slow sorption rate indicates a lack of surface functional groups. The sorption of Cu(II) by oxygenated and unoxygenated chars was also found to occur via three and two distinct stages, respectively. Copyright © 2010 Elsevier Inc. All rights reserved.

CFD Simulation of Entrained Flow Gasification With Improved Devolatilization and Char Consumption Submodels

KAUST Repository

Kumar, Mayank; Zhang, Cheng; Monaghan, Rory F. D.; Singer, Simcha L.; Ghoniem, Ahmed F.

2009-01-01

In this work, we use a CFD package to model the operation of a coal gasifier with the objective of assessing the impact of devolatilization and char consumption models on the accuracy of the results. Devolatilization is modeled using the Chemical Percolation Devolitilization (CPD) model. The traditional CPD models predict the rate and the amount of volatiles released but not their species composition. We show that the knowledge of devolatilization rates is not sufficient for the accurate prediction of char consumption and a quantitative description of the devolatilization products, including the chemical composition of the tar, is needed. We incorporate experimental data on devolatilization products combined with modeling of the tar composition and reactions to improve the prediction of syngas compositions and carbon conversion. We also apply the shrinking core model and the random pore model to describe char consumption in the CFD simulations. Analysis of the results indicates distinct regimes of kinetic and diffusion control depending on the particle radius and injection conditions for both char oxidation and gasification reactions. The random pore model with Langmuir-Hinshelwood reaction kinetics are found to be better at predicting carbon conversion and exit syngas composition than the shrinking core model with Arrhenius kinetics. In addition, we gain qualitative and quantitative insights into the impact of the ash layer surrounding the char particle on the reaction rate. Copyright © 2010 by ASME.

Study of bio-oil and bio-char production from algae by slow pyrolysis

International Nuclear Information System (INIS)

Chaiwong, K.; Kiatsiriroat, T.; Vorayos, N.; Thararax, C.

2013-01-01

This study examined bio-oil and bio-char fuel produced from Spirulina Sp. by slow pyrolysis. A thermogravimetric analyser (TGA) was used to investigate the pyrolytic characteristics and essential components of algae. It was found that the temperature for the maximum degradation, 322 °C, is lower than that of other biomass. With our fixed-bed reactor, 125 g of dried Spirulina Sp. algae was fed under a nitrogen atmosphere until the temperature reached a set temperature between 450 and 600 °C. It was found that the suitable temperature to obtain bio-char and bio-oil were at approximately 500 and 550 °C respectively. The bio-oil components were identified by a gas chromatography/mass spectrometry (GC–MS). The saturated functional carbon of the bio-oil was in a range of heavy naphtha, kerosene and diesel oil. The energy consumption ratio (ECR) of bio-oil and bio-char was calculated, and the net energy output was positive. The ECR had an average value of 0.49. -- Highlights: •Bio-oil and bio-char fuel produced from Spirulina Sp. by slow pyrolysis. •Suitable temperature to obtained bio-oil and bio-char were at about 550 and 500 °C. •Saturated functional carbon of bio-oil was heavy naphtha, kerosene, diesel oil. •ECR had an average value of 0.49

Spontaneous human combustion in the light of the 21st century.

Science.gov (United States)

Koljonen, Virve; Kluger, Nicolas

2012-01-01

The term "spontaneous human combustion" refers to a situation when a human body is found with significant portions of the middle parts of the body reduced to ashes, much less damage to the head and extremities, and minimal damage to the direct surroundings of the body. Typically, no observable source of ignition is found in the vicinity of the victim and a bad smelling oily substance is noted. In the past, such a situation was erroneously attributed to supernatural powers, as such phenomenon occurs in the absence of any witness. The purpose of this review article was to analyze articles published from January 1, 2000, on this unique type of burn injury. Further aims were to gather and present data on the causes and events leading to this situation. The literature was reviewed with PubMed interface using the key words spontaneous human combustion and preternatural combustion. Specific inclusion criteria resulted in 12 patients. A unique sequence of events takes place for the human body to incinerate to ashes. The flame burn victim has to die for the body fat to start melting. A tear in the skin has to occur for the melted fat to impregnate the charred clothes, igniting a wick effect that produces localized heat for extended period. A phenomenon called spontaneous human combustion is reality. The term "spontaneous human combustion" has nuances which are not applicable to this situation or to these modern times, therefore we suggest a new term "fat wick burns."

Novel intrinsic-based submodel for char particle gasification in entrained-flow gasifiers: Model development, validation and illustration

International Nuclear Information System (INIS)

Schulze, S.; Richter, A.; Vascellari, M.; Gupta, A.; Meyer, B.; Nikrityuk, P.A.

2016-01-01

Highlights: • Model resolving intra-particle species transport for char conversion was formulated. • TGA experiments of char particle conversion in gas flow were conducted. • The experimental results for char conversion validated the model. • CFD simulations of endothermic reactor with developed model were carried out. - Abstract: The final carbon conversion rate is of critical importance in the efficiency of gasifiers. Therefore, comprehensive modeling of char particle conversion is of primary interest for designing new gasifiers. This work presents a novel intrinsic-based submodel for the gasification of a char particle moving in a hot flue gas environment considering CO 2 and H 2 O as inlet species. The first part of the manuscript describes the model and its derivation. Validations against experiments carried out in this work for German lignite char are reported in the second part. The comparison between submodel predictions and experimental data shows good agreement. The importance of char porosity change during gasification is demonstrated. The third part presents the results of CFD simulations using the new submodel and a surface-based submodel for a generic endothermic gasifier. The focus of CFD simulations is to demonstrate the crucial role of intrinsic based heterogeneous reactions in the adequate prediction of carbon conversion rates.

Removal of hexavalent Cr by coconut coir and derived chars--the effect of surface functionality.

Science.gov (United States)

Shen, Ying-Shuian; Wang, Shan-Li; Tzou, Yu-Min; Yan, Ya-Yi; Kuan, Wen-Hui

2012-01-01

The Cr(VI) removal by coconut coir (CC) and chars obtained at various pyrolysis temperatures were evaluated. Increasing the pyrolysis temperature resulted in an increased surface area of the chars, while the corresponding content of oxygen-containing functional groups of the chars decreased. The Cr(VI) removal by CC and CC-derived chars was primarily attributed to the reduction of Cr(VI) to Cr(III) by the materials and the extent and rate of the Cr(VI) reduction were determined by the oxygen-containing functional groups in the materials. The contribution of pure Cr(VI) adsorption to the overall Cr(VI) removal became relatively significant for the chars obtained at higher temperatures. Accordingly, to develop a cost-effective method for removing Cr(VI) from water, the original CC is more advantageous than the carbonaceous counterparts because no pyrolysis is required for the application and CC has a higher content of functional groups for reducing Cr(VI) to less toxic Cr(III). Copyright © 2011 Elsevier Ltd. All rights reserved.

The role of char and tar in determining the gas-phase partitioning of nitrogen during biomass gasification

International Nuclear Information System (INIS)

Broer, Karl M.; Brown, Robert C.

2015-01-01

Highlights: • Switchgrass was gasified at an equivalence ratio of zero and 650–850 °C. • Short residence times were employed to minimize secondary reactions. • Char- and tar-bound nitrogen, NH_3, HCN, and N_2 were all significant products. • Increasing temperature leads to increased release of gaseous nitrogen compounds. • Kinetic models of gasification should include nitrogen release from char and tar. - Abstract: Gasification is an attractive option for converting biomass into fuels and chemicals. Most biomass contains significant amounts of fuel-bound nitrogen (FBN), which partially converts into ammonia (NH_3) and hydrogen cyanide (HCN) during gasification. These nitrogen compounds are problematic as they can lead to NO_X emissions or catalyst poisoning in downstream applications of syngas. FBN can convert to other products as well, including diatomic nitrogen (N_2), char-bound nitrogen (char-N), and tar-bound nitrogen (tar-N). Efforts to predict concentrations of NH_3 and HCN have been hindered by a lack of accurate, comprehensive measurements of nitrogen partitioning among gasification products. The present study gasified switchgrass under allothermal, short residence time conditions and measured NH_3, HCN, char-N, and tar-N as a function of temperature in the range of 650–850 °C with diatomic nitrogen determined by difference. It was found that a major portion of FBN was retained in the char and tar products. As temperature was increased, char and tar were consumed, releasing nitrogen as gaseous NH_3 and HCN. This increase in undesirable nitrogen compounds is contrary to the predictions of most gasification models, which overlook the presence of significant nitrogen in char and tar even if they include tar cracking and char gasification reactions. The results of this study demonstrate that gas-phase reactions alone are not sufficient to predict the fate of nitrogen during gasification. In order for modeling efforts to obtain more accurate

Effect of cation exchange on the subsequent reactivity of lignite chars to steam. [108 references

Energy Technology Data Exchange (ETDEWEB)

Hippo, E. J.; Walker, Jr., P. L.

1977-03-01

The purpose of this investigation is to determine the role which cations in coal play in the subsequent reactivity of chars. It is hoped that this investigation will aid in an understanding of the catalytic nature of inorganic constituents in coal during its gasification. It was found that increased heat treatment temperature decreased reactivity. The decrease in reactivity was shown to be due, at least in part, to the changes in the nature of the cation with increased heat treatment temperature. Reactivity was found to be a linear function of the amount of Ca(++) exchange on the demineralized coal. The constant utilization factor over the wide range of loadings employed indicated that below 800/sup 0/C the calcium did not markedly sinter. Potassium, sodium, and calcium-containing chars were found to be much more reactive than the iron and magnesium-containing chars. However, the iron and magnesium containing chars were more reactive than chars produced from the demineralized coal. The iron char was highly active at first but the iron phase was quickly oxidized to a comparatively unreactive ..gamma..Fe/sub 2/O/sub 3/-Fe/sub 3/O/sub 4/ phase. The state of magnesium was found to be MgO. Sodium and calcium were equally active as catalysts but not as active as potassium.

Porous structure and morphology of granular chars from flash and conventional pyrolysis of grape seeds

International Nuclear Information System (INIS)

Jimenez-Cordero, Diana; Heras, Francisco; Alonso-Morales, Noelia; Gilarranz, Miguel A.; Rodriguez, Juan J.

2013-01-01

This work studies the influence of the operating conditions used in the pyrolysis of grape seeds on the morphology and textural properties of the chars resulting. Flash and conventional (283 K min −1 heating rate) pyrolysis have been used within a wide range of temperature (300–1000 °C). The effect of a pretreatment for oil extraction has also been studied. The porous structure of the chars was characterized by adsorption of N 2 at 77 K, Ar at 77 K and 87 K, and CO 2 at 273 K and mercury intrusion porosimetry. The morphology was analyzed by scanning electron microscopy. All the materials prepared revealed an essentially microporous structure, with a poor or even negligible contribution of mesopores. Increasing pyrolysis temperature led to higher specific surface areas and lower pore size. The highest specific surface area values occurred within 700–800 °C, reaching up to 500 m 2 g −1 with pore sizes in the 0.4–1.1 nm range. No significant morphological changes were observed upon carbonization so that the resulting chars were granular materials of similar size than the starting grape seeds. The hollow core structure of the chars, with most of the material allocated at the periphery of the granules can help to overcome the mass transfer limitations of most common (solid or massive) granular activated carbons. The chars showed a good mechanical strength during attrition tests. These chars can be potential candidates for the preparation of granular carbons molecular sieve or activated carbons raw materials. -- Highlights: •We use a raw material that has a very low price and a high availability. •Not very much attention has been paid to this waste for carbonaceous materials preparation. •The chars obtained have high specific surface area that is an interesting starting point for later activation processes. •The chars show a micro-macro porous bimodal distribution. •Pyrolysis does not affect to morphology or initial seed, leading a carbonized

Reactivity of coal chars prepared in a fluidised bed reactor at different burn-off degrees

Energy Technology Data Exchange (ETDEWEB)

Moreno, A.H.; Arenillas, A.; Rubiera, F.; Fuente, E.; Pis, J.J. [Inst. Nacional del Carbon, Oviedo (Spain)

1997-12-31

The main goal of this work has been to study the effect of the textural properties of coal chars, obtained from partially burned coal, on their reactivity to oxygen. A low volatile bituminous coal was used to prepare chars, with different levels of burn-off, in a bench-scale fluidised bed reactor. Textural characterisation of the samples was accomplished by measuring true (helium) and apparent (mercury) densities, and mercury porosimetry. An increase in the burn-off degree gave rise to a densification of the chars. Porosity development greatly changed during progressive burning of the samples. DTG burning profiles and isothermal gasification were utilised to estimate the reactivities of the precursor coal and its partially burned chars. Reactivity reached a maximum value at an intermediate burn-off and strongly decreased at higher burn-off degrees. (orig.)

Modeling and evaluation of chromium remediation from water using low cost bio-char, a green adsorbent

International Nuclear Information System (INIS)

Mohan, Dinesh; Rajput, Shalini; Singh, Vinod K.; Steele, Philip H.; Pittman, Charles U.

2011-01-01

Oak wood and oak bark chars were obtained from fast pyrolysis in an auger reactor at 400-450 deg. C. These chars were characterized and utilized for Cr(VI) remediation from water. Batch sorption studies were performed at different temperatures, pH values and solid to liquid ratios. Maximum chromium was removed at pH 2.0. A kinetic study yielded an optimum equilibrium time of 48 h with an adsorbent dose of 10 g/L. Sorption studies were conducted over a concentration range of 1-100 mg/L. Cr(VI) removal increased with an increase in temperature (Q Oakwood o : 25 deg. C = 3.03 mg/g; 35 deg. C = 4.08 mg/g; 45 deg. C = 4.93 mg/g and Q Oakbark o : 25 deg. C = 4.62 mg/g; 35 deg. C = 7.43 mg/g; 45 deg. C = 7.51 mg/g). More chromium was removed with oak bark than oak wood. The char performances were evaluated using the Freundlich, Langmuir, Redlich-Peterson, Toth, Radke and Sips adsorption isotherm models. The Sips adsorption isotherm model best fits the experimental data [high regression (R 2 ) coefficients]. The overall kinetic data was satisfactorily explained by a pseudo second order rate expression. Water penetrated into the char walls exposing Cr(VI) to additional adsorption sites that were not on the surfaces of dry char pores. It is remarkable that oak chars (S BET : 1-3 m 2 g -1 ) can remove similar amounts of Cr(VI) as activated carbon (S BET : ∼1000 m 2 g -1 ). Thus, byproduct chars from bio-oil production might be used as inexpensive adsorbents for water purification. Char samples were successfully used for chromium remediation from contaminated surface water with dissolved interfering ions.

Modeling and evaluation of chromium remediation from water using low cost bio-char, a green adsorbent.

Science.gov (United States)

Mohan, Dinesh; Rajput, Shalini; Singh, Vinod K; Steele, Philip H; Pittman, Charles U

2011-04-15

Oak wood and oak bark chars were obtained from fast pyrolysis in an auger reactor at 400-450 °C. These chars were characterized and utilized for Cr(VI) remediation from water. Batch sorption studies were performed at different temperatures, pH values and solid to liquid ratios. Maximum chromium was removed at pH 2.0. A kinetic study yielded an optimum equilibrium time of 48 h with an adsorbent dose of 10 g/L. Sorption studies were conducted over a concentration range of 1-100mg/L. Cr(VI) removal increased with an increase in temperature (Q(Oak wood)(°): 25 °C = 3.03 mg/g; 35 °C = 4.08 mg/g; 45 °C = 4.93 mg/g and Q(Oakbark)(°): 25 °C = 4.62 mg/g; 35 °C = 7.43 mg/g; 45 °C = 7.51 mg/g). More chromium was removed with oak bark than oak wood. The char performances were evaluated using the Freundlich, Langmuir, Redlich-Peterson, Toth, Radke and Sips adsorption isotherm models. The Sips adsorption isotherm model best fits the experimental data [high regression (R(2)) coefficients]. The overall kinetic data was satisfactorily explained by a pseudo second order rate expression. Water penetrated into the char walls exposing Cr(VI) to additional adsorption sites that were not on the surfaces of dry char pores. It is remarkable that oak chars (S(BET): 1-3m(2)g(-1)) can remove similar amounts of Cr(VI) as activated carbon (S(BET): ∼ 1000 m(2)g(-1)). Thus, byproduct chars from bio-oil production might be used as inexpensive adsorbents for water purification. Char samples were successfully used for chromium remediation from contaminated surface water with dissolved interfering ions. Copyright © 2011 Elsevier B.V. All rights reserved.

Micro-PIXE studies of char populations in northern Canada

International Nuclear Information System (INIS)

Campbell, J.L.; Babaluk, J.A.; Halden, N.M.; Kristofferson, A.H.; Maxwell, J.A.; Mejia, S.R.; Reist, J.D.; Teesdale, W.J.

1999-01-01

Micro-PIXE analysis of trace elements in otoliths has been used as the basis for several projects on char, a fish that is important for aboriginal subsistence fisheries in Arctic Canada. Life-history patterns were originally inferred from micro-PIXE line scans of Sr distribution. These were confirmed by superposition of Sr distribution patterns on optical images of otoliths of tag-recaptured fish. Char from various populations showed differentiation in otolith primordial Sr concentration; this enables us to differentiate biological stocks and, it is hoped, eventually to assign individuals from mixed-stock fisheries to their stock of origin. Zn oscillations also correlate with annular structure and provide additional temporally constrained information on fish habitat and behaviour

Characterization of a Neochlamydia-like Bacterium Associated with Epitheliocystis in Cultured Artic Char Salvelinus alpinus

Science.gov (United States)

Infections of branchial epithelium by intracellular gram-negative bacteria, termed epitheliocystis, have limited culture of Arctic char (Salvelinus alpinus). To characterize a bacterium associated with epitheliocystis in cultured char, gills were sampled for histopathologic examination, conventional...

Electron paramagnetic resonance and dynamic nuclear polarization of char suspensions: surface science and oximetry

DEFF Research Database (Denmark)

Clarkson, R B; Odintsov, B M; Ceroke, P J

1998-01-01

; they can be calibrated and used for oximetry. Biological stability and low toxicity make chars good sensors for in vivo measurements. Scalar and dipolar interactions of water protons at the surfaces of chars may be utilized to produce dynamic nuclear polarization (DNP) of the nuclear spin population...

Combustion properties, water absorption and grindability of raw/torrefied biomass pellets and Silantek coal

Science.gov (United States)

Matali, Sharmeela; Rahman, Norazah Abdul; Idris, Siti Shawaliah; Yaacob, Nurhafizah

2017-12-01

Torrefaction, also known as mild pyrolysis, is proven to convert raw biomass into a value-added energy commodity particularly for application in combustion and co-firing systems with improved storage and handling properties. This paper aims to compare the characteristics of Malaysian bituminous coal i.e. Silantek coal with raw and torrefied biomass pellet originated from oil palm frond and fast growing tree species, Leucaena Leucocephala. Biomass samples were initially torrefied at 300 °C for 60 minutes. Resulting torrefied biomass pellets were analysed using a number of standard fuel characterisation analyses i.e. elemental analysis, proximate analysis and calorific content (high heating values) experiments. Investigations on combustion characteristics via dynamic thermogravimetric analysis (TGA), grindability and moisture uptake tests were also performed on the torrefied biomass pellets. Better quality bio-chars were produced as compared to its raw forms and with optimal process conditions, torrefaction may potentially produces a solid fuel with combustion reactivity and porosity equivalent to raw biomass while having compatible energy density and grindability to coal.

Contributing variables for sustainable livelihood status of the char women in Bangladesh

Directory of Open Access Journals (Sweden)

S. Al-Amin

2012-03-01

Full Text Available The main purpose of the study was to determine the contribution of variables to the sustainable livelihood status of char women. The sustainable livelihood status of a char woman was measured by computing a “sustainable livelihood status score” which is considering six major aspects of her livelihoods: food security, ability to provide family education, health and sanitation, shelter and family assets, clothing condition and social upliftment. Data were collected from 200 randomly selected char women by using interview schedule in two Upazilla of Jamalpur district in Bangladesh during November 2006 to March 2007. More than two-fifths (67.5 per cent of the char women were found under “medium sustainable livelihood status” compared to more than one-fifth (20.5 per cent of them belongs to ‘low sustainable livelihood status’ and only 12 per cent to “high sustainable livelihood status”. Pearson correlation test depicted that out of 16 variables, 13 had significant positive relationships with the sustainable livelihood status. Results of stepwise multiple regression analysis revealed that five variables namely, annual income, agricultural knowledge, income generating activities, family education and organizational participation contributed significantly which combindly explained 76.3 per cent of total variation to the sustainable livelihood status. Path analysis indicated that these variables had both direct and indirect effects to the sustainable livelihood status. Women who had more annual income, better agricultural knowledge, participation in income generating activities, more family education and more organizational participation were found to better sustainable livelihood status in char area. Government or concern other authorities need to give attention to these variables for any sustainable livelihood upliftment programme.

Leaching of major and trace elements from paper-plastic gasification chars. An experimental and modelling study

Energy Technology Data Exchange (ETDEWEB)

Fuente-Cuesta, A.; Lopez-Anton, M.A.; Diaz-Somoano, M.; Martinez-Tarazona, M.R. [Instituto Nacional del Carbon CSIC, C/Francisco Pintado Fe No 26, 33011, Oviedo (Spain); Van Zomeren, A.; Cieplik, M. [Energy research Centre of the Netherlands ECN, Biomass, P.O. Box 1, 1755 ZG, Petten (Netherlands)

2013-01-15

The control of soluble metal species in the sub-product leachate generated in electricity production processes is of great concern from an environmental and health point of view. Unlike fly ash, the leaching behaviour of char materials has received little attention. Yet, these solids are captured together with fly ashes in the particle control devices of power plants and are emitted in the same way as by-products. The present study was carried out using two char samples: (1) a raw char and (2) the same type of char employed in a previous study so that it could serve as a sorbent for mercury species in gas phase. The char samples were by-products (residues) that had been generated during the gasification of plastic and paper waste. The leachates were analyzed for the following elements: Al, Ca, Si, Mg, Ba, Cu, Ni, Pb, Zn, Mo and Hg. In addition, geochemical modelling of the leaching test results was employed to identify the underlying chemical processes that led to the release of toxic elements. The results showed that at alkaline pH values, sorption on the solid surfaces of the char was negligible due to the inorganic complexation of cations in the solution. When the char was used as mercury sorbent slight changes occurred on the reactive surface resulting in the modification of the binding of some elements. As the pH increased, complexation with dissolved organic matter played a more important role in the case of some elements such as Cu because of the greater concentration of dissolved organic matter in solution.

Advances in CO_2 gasification reactivity of biomass char through utilization of radio frequency irradiation

International Nuclear Information System (INIS)

Lahijani, Pooya; Mohammadi, Maedeh; Zainal, Zainal Alimuddin; Mohamed, Abdul Rahman

2015-01-01

A straightforward and well-known reaction for CO_2 activation is the “Boudouard reaction”, wherein, CO_2 is reacted with carbon (char) to produce CO. In this study, a RF (radio frequency) heating system was developed to perform the Boudouard reaction by passing CO_2 through a packed bed of PNS (pistachio nut shell) char. High CO_2 conversion of 84% was achieved at 850 °C. When similar experiments were performed in thermal electric furnace, the conversion was only 38%. For further expanding the knowledge on RF-induced gasification, sodium (Na) was incorporated into char skeleton and gasified with CO_2 under RF irradiation. RF gasification of Na-catalyzed char pronouncedly improved in the reaction, where sustainable CO_2 conversion of 99% was attained at 850 °C. The predominance of RF over thermal heating was highly reflected in kinetic studies, where the activation energies of 26.7, 46.9 and 183.9 kJ/mol were obtained for catalytic and non-catalytic RF and thermal gasification, respectively. In RF gasification studies, it was attempted to improve the quality of mix gases, simulating air and steam gasification gas compositions, through the Boudouard reaction. The heating value of the gases simulating air and steam gasification improved from 6.4 to 8.0 MJ/m"3 and 7.6–10.4 MJ/m"3, respectively. - Highlights: • We study radio frequency-induced CO_2 gasification of pistachio nut shell char. • We achieve very high CO_2 conversion of 99% in RF gasification of Na-catalyzed char. • E_a of 47 and 184 kJ/mol obtained for RF-assisted and conventional CO_2 gasification. • Heating value of synthesis gas improved via RF-induced char-CO_2 gasification.

Improvement of biomass char-CO{sub 2} gasification reactivity using microwave irradiation and natural catalyst

Energy Technology Data Exchange (ETDEWEB)

Lahijani, Pooya, E-mail: pooya.lahijani@gmail.com [Biomass and Bioenergy Laboratory, School of Mechanical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Mohammadi, Maedeh, E-mail: m.mohammadi@nit.ac.ir [Faculty of Chemical Engineering, Babol Noushirvani University of Technology, 47148 Babol (Iran, Islamic Republic of); Zainal, Zainal Alimuddin, E-mail: mezainal@eng.usm.my [Biomass and Bioenergy Laboratory, School of Mechanical Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Mohamed, Abdul Rahman, E-mail: chrahman@usm.my [Low Carbon Economy (LCE) Research Group, School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

2015-03-20

Highlights: • We study microwave-induced gasification of EFB ash-loaded biomass char with CO{sub 2}. • Synergistic effect of microwave and catalyst resulted in CO{sub 2} conversion of 93%. • Gasification of pristine char using conventional heating gives CO{sub 2} conversion of 58%. • E{sub a} of 74 and 247 kJ/mol were obtained for microwave and conventional CO{sub 2} gasification. - Abstract: In char-CO{sub 2} gasification, the highly endothermic nature of the Boudouard reaction (CO{sub 2} (g) + C (s) ↔ 2CO (g)) dictates use of very high temperatures to shift the equilibrium towards CO production. In this study, such high temperature (750–900 °C) was provided by microwave irradiation. A microwave heating system was developed to perform the gasification tests by passing CO{sub 2} through a packed bed of oil palm shell (OPS) char. In order to speed up the microwave-induced CO{sub 2} gasification, ash of palm empty fruit bunch (EFB) was used as natural catalyst (rich in potassium) and incorporated into the skeleton of the OPS char. The synergistic effect of microwave and catalyst concluded to very encouraging results, where a CO{sub 2} conversion of 93% was achieved at 900 °C, within 60 min microwave gasification. In comparison, CO{sub 2} conversion in thermal gasification (conventional heating) of pristine OPS char was only 58% under the same operating condition.

The potential applications of using compost chars for removing the hydrophobic herbicide atrazine from solution.

Science.gov (United States)

Tsui, Lo; Roy, William R

2008-09-01

One commercial compost sample was pyrolyzed to produce chars as a sorbent for removing the herbicide atrazine from solution. The sorption behavior of compost-based char was compared with that of an activated carbon derived from corn stillage. When compost was pyrolyzed, the char yield was greater than 45% when heated under air, and 52% when heated under N(2). In contrast, when the corn stillage was pyrolyzed under N(2), the yield was only 22%. The N(2)-BET surface area of corn stillage activated carbon was 439 m(2)/g, which was much greater than the maximum compost char surface area of 72 m(2)/g. However, the sorption affinity of the compost char for dissolved atrazine was comparable to that of the corn stillage activated carbon. This similarity could have resulted from the initial organic waste being subjected to a relatively long period of thermal processes during composting, and thus, the compost was more thermally stable when compared with the raw materials. In addition, microorganisms transformed the organic wastes into amorphous humic substances, and thus, it was likely that the microporisity was enhanced. Although this micropore structure could not be detected by the N(2)-BET method, it was apparent in the atrazine sorption experiment. Overall, the experimental results suggested that the compost sample in current study was a relatively stable material thermally for producing char, and that it has the potential as a feed stock for making high-quality activated carbon.

A Study on Recycling of Spent Mushroom Substrate to Prepare Chars and Activated Carbon

Directory of Open Access Journals (Sweden)

Yuhui Ma

2014-05-01

Full Text Available Chars were obtained from spent mushroom substrate (SMS via pyrolysis. It was found that as the pyrolysis temperature increased from 400 to 700 °C, the char yield decreased from 45.10 to 33.79 wt.% and the higher heating value increased from 17.32 to 22.72 MJ/kg. The largest BET surface area (13 m2/g was created at 500 °C. Hydrogen atoms were continuously lost during pyrolysis, whereas oxygen atoms were difficult to eliminate. Whewellite, calcite, lime, and quartz were the minerals in the chars, and their forms and crystallinity changed with changing pyrolysis temperature. Activated carbon with a BET surface area of 1023 m2/g and a total pore volume of 0.595 cm3/g was obtained from the char prepared at 500 °C. Its characteristics were studied by N2-adsorption, Fourier transform infrared spectroscopy (FTIR, and X-ray diffraction (XRD. The pyrolysis and KOH-activation processes were investigated by thermogravimetric analysis (TGA. The results showed that the pyrolysis of SMS occurred primarily between 217 and 375 °C and that the energies needed for the pyrolysis reactions were relatively low due to the prior mushroom cultivation. Furthermore, lignin was incompletely decomposed in the char prepared at 500 °C, and KOH suppressed tar evolution and reduced the energy needed to decompose the residual lignin during activation.

Research on the Combustion Characteristics and Kinetic Analysis of the Recycling Dust for a COREX Furnace

Directory of Open Access Journals (Sweden)

Haiyang Wang

2017-02-01

Full Text Available Thermogravimetric analysis of recycling dust (RD from the melter gasifier of COREX, coke1 (C-1, coke2 (C-2 and coal char (CC under 70% oxygen atmosphere was carried out using thermal balance. The chemical composition and physical structure of the samples were investigated. The characteristic temperatures and comprehensive combustion characteristic indexes were calculated and kinetic parameters during the combustion process were calculated as well using a distributed activation energy model (DAEM. The results show that the carbon in the recycling dust originates from unconsumed CC and coke fines, and the average stacking height of carbon in RD is larger than that of C-1, C-2 and CC. The conversion curves of RD are different from those of C-1, C-2 and CC, and there are two peaks in the RD conversion rate curves. The combustion profiles of RD moves to a higher temperature zone with increasing heating rates. The average activation energies of their combustion process for RD, C-1, C-2 and CC range from 191.84 kJ/mol to 128.31 kJ/mol. The activation energy for recycling dust increases as the fractional conversion increases, but the value for C-1, C-2 and CC decreases with increasing conversion, indicating different combustion mechanisms.

Preparation of combustible material from high sulphur coal by means of pyrolysis: magnetic separation; Obtencion de combustibles limpios a partir de carbones con altos contenidos en azure mediante procesos de pirolisis: separacion magnetica

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-11-01

Basic studies on coal desulphurization by pyrolysis have been carried out with a series of low rank coals with high total sulphur contents and differences in the distribution of sulphur forms. The evolved sulphur compounds were studied by sulphide selective electrode H{sub 2}S and Fourier transform infrared (FTIR) spectroscopy. The mechanisms affecting the sulphur removal during pyrolysis have been studied by scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and photoelectronic spectroscopy (XPS). A sample coal of 11 Tm, representative of the Teruel basins was processed at pilot scale in a rotary kiln (coal HR). A series of pyrolysis runs simulating the experimental conditions of the rotary kiln were also carried out in laboratory scale. The magnetic behaviour of the chars from the rotary kiln and from the lab-scale pyrolysis was tested. The efficiency of the desulphurization, including pyrolysis and magnetic separation, was calculated. Chars from rotary kiln were tested by thermogravimetric analysis, air reactivity and carbon efficiency combustion in fluidized bed.

Effect of Kaolin Clay and Alumina on Thermal Performance and Char Morphology of Intumescent fire retardant coating

Directory of Open Access Journals (Sweden)

aziz Hammad

2014-07-01

Full Text Available Intumescent fire retardant coating (IFRC have been developed by using ammonium polyphosphate, expandable graphite, melamine, boric acid, kaolin clay and alumina as fillers bound together with epoxy resin and cured with the help of curing agent. Five different formulations were developed with and without using fillers. Cured samples were burned in furnace at 500°C for 2h for char expansion. Bunsen burner test was performed for 1h using UL-94 vertical burning test to investigate the thermal performance of IFRC. The resultant char obtained after burning of coated samples were characterized by using field emission scanning electron microscopy for char morphology. Char composition was analyzed by using fourier transform infrared spectroscopy. Thermogravimetric analysis was carried out to investigate the residual weight of coating. Results showed that formulation with 0.5 weight % of kaolin clay and 0.5 weight % of alumina provide best thermal performance, uniform and multi-porous char structure with high anti-oxidation property.

Reactivity and burnout of wood fuels

DEFF Research Database (Denmark)

Dall'Ora, Michelangelo

This thesis deals with the combustion of wood in pulverised fuel power plants. In this type of boiler, the slowest step in the wood conversion process is char combustion, which is one of the factors that not only determine the degree of fuel burnout, but also affect the heat release profile...... of different aspects relevant to wood combustion, including wood structure and composition, wood pyrolysis, wood char properties and wood char oxidation. The full scale campaign, which is the subject of Chapter 3, included sampling of wood fuel before and after milling and sampling of gas and particles...... at the top of the combustion chamber. The collected samples and data are used to obtain an evaluation of the mills in operation at the power plant, the particle size distribution of the wood fuel, as well as the char conversion attained in the furnace. In Chapter 4 an experimental investigation...

Temperature influence on the fast pyrolysis of manure samples: char, bio-oil and gases production

Science.gov (United States)

Fernandez-Lopez, Maria; Anastasakis, Kostas; De Jong, Wiebren; Valverde, Jose Luis; Sanchez-Silva, Luz

2017-11-01

Fast pyrolysis characterization of three dry manure samples was studied using a pyrolyzer. A heating rate of 600°C/s and a holding time of 10 s were selected to reproduce industrial conditions. The effect of the peak pyrolysis temperature (600, 800 and 1000°C) on the pyrolysis product yield and composition was evaluated. Char and bio-oil were gravimetrically quantified. Scanning electron microscopy (SEM) was used to analyse the char structure. H2, CH4, CO and CO2 were measured by means of gas chromatography (GC). A decrease in the char yield and an increase of the gas yield were observed when temperature increased. From 800°C on, it was observed that the char yield of samples Dig R and SW were constant, which indicated that the primary devolatilization reactions stopped. This fact was also corroborated by GC analysis. The bio-oil yield slightly increased with temperature, showing a maximum of 20.7 and 27.8 wt.% for samples Pre and SW, respectively, whereas sample Dig R showed a maximum yield of 16.5 wt.% at 800°C. CO2 and CO were the main released gases whereas H2 and CH4 production increased with temperature. Finally, an increase of char porosity was observed with temperature.

Near-Zero Emissions Oxy-Combustion Flue Gas Purification Task 2: SOx/Nox/Hg Removal for High Sulfur Coal

Energy Technology Data Exchange (ETDEWEB)

Nick Degenstein; Minish Shah; Doughlas Louie

2012-05-01

The goal of this project is to develop a near-zero emissions flue gas purification technology for existing PC (pulverized coal) power plants that are retrofitted with oxy-combustion technology. The objective of Task 2 of this project was to evaluate an alternative method of SOx, NOx and Hg removal from flue gas produced by burning high sulfur coal in oxy-combustion power plants. The goal of the program was not only to investigate a new method of flue gas purification but also to produce useful acid byproduct streams as an alternative to using a traditional FGD and SCR for flue gas processing. During the project two main constraints were identified that limit the ability of the process to achieve project goals. 1) Due to boiler island corrosion issues >60% of the sulfur must be removed in the boiler island with the use of an FGD. 2) A suitable method could not be found to remove NOx from the concentrated sulfuric acid product, which limits sale-ability of the acid, as well as the NOx removal efficiency of the process. Given the complexity and safety issues inherent in the cycle it is concluded that the acid product would not be directly saleable and, in this case, other flue gas purification schemes are better suited for SOx/NOx/Hg control when burning high sulfur coal, e.g. this project's Task 3 process or a traditional FGD and SCR.

Disintegration of beech wood char during thermal conversion

DEFF Research Database (Denmark)

Hindsgaul, Claus

In the present work the processes occurring in the structures of slowly pyrolysed beech wood char during thermal gasification have been investigated. Emphasis was put on physical changes and gas transport properties during conversion. The highly anisotropic structure of wood was preserved in its ...

Reactivity and burnout of wood fuels

Energy Technology Data Exchange (ETDEWEB)

Dall' Ora, M.

2011-07-01

This thesis deals with the combustion of wood in pulverised fuel power plants. In this type of boiler, the slowest step in the wood conversion process is char combustion, which is one of the factors that not only determine the degree of fuel burnout, but also affect the heat release profile in the boiler and thereby the overall operation and efficiency of the plant. Chapter 1 consists of an introduction to thermal conversion of biomass fuels as well as a description of a Danish power plant where a measuring campaign was carried out as part of this project. Chapter 2 is a brief literature review of different aspects relevant to wood combustion, including wood structure and composition, wood pyrolysis, wood char properties and wood char oxidation. The full scale campaign, which is the subject of Chapter 3, included sampling of wood fuel before and after milling and sampling of gas and particles at the top of the combustion chamber. The collected samples and data are used to obtain an evaluation of the mills in operation at the power plant, the particle size distribution of the wood fuel, as well as the char conversion attained in the furnace. In Chapter 4 an experimental investigation on the relation between pyrolysis of wood in boiler-like conditions and wood char properties is presented. Chars from pine and beech wood were produced by fast pyrolysis in an entrained flow reactor and by slow pyrolysis in a thermogravimetric analyser. The influence of pyrolysis temperature, heating rate and particle size on char yield and morphology was investigated. The applied pyrolysis temperature varied in the range 673-1673 K for slow pyrolysis and 1073-1573 K for fast pyrolysis. The chars were oxidised in a thermogravimetric analyser and the mass loss data were used to determine char oxidation reactivity. Char yield from fast pyrolysis (104-105 K/s) was as low as 1-6% on a dry ash free basis, whereas it was about 15-17% for slow pyrolysis (10-20 K/min); char yield decreased as

Bio-oil and bio-char production from biomass and their structural analyses

International Nuclear Information System (INIS)

Kilic, Murat; Özsin, Gamzenur; Pütün, Ayşe E.; Pütün, Ersan

2015-01-01

Energy demand is increasing day by day because of the rapid developments in the population, industrialization and urbanisation. Since, fossil fuels will be at the verge of getting extinct, researches are mostly focused on the renewable sources, such as biomass, in recent years. This paper provides an environmentally friendly process to convert waste biomass samples to bio-oil and bio-char by pyrolysis. For this purpose, pyrolysis characteristics of pomegranate peels under inert atmosphere were studied by using both TGA to analysis decomposition behaviour and a batch reactor to investigate product yields and properties. The properties of bio-oil and bio-char were investigated by different analytical techniques such as GC-MS, FT-IR, SEM, He pycnometry and elemental analysis. As a consequence, it is possible to obtain bio-oil, which has similar properties like petroleum hydrocarbons, and to obtain bio-char, which can be further used as a solid fuel or a carbonaceous adsorbent material via pyrolysis process. (full text)

Investigation of the Anisotropic Behavior of Wood Char Particles during Gasification

DEFF Research Database (Denmark)

Henriksen, Ulrik Birk; Hindsgaul, Claus; Qvale, Einar Bjørn

2006-01-01

(R) and tangential (T) directions. Despite this, this property has normally not been included in mathematical model descriptions of gasification of thermally thick particles. The present paper describes a study of the influence of the anisotropy on the reactivity of thermally thick char particles...... of the normal to the greater surface of the slabs L, R, or T (see Figure 8). When the smaller surfaces were coated with alumina silicate, the gasification agent could only enter the interior of the slabs through the greater surfaces. Thermally thick char particles from beech and pine reacted more slowly...

CHAR and BURNMAC - burnup modules of the AUS neutronics code system

International Nuclear Information System (INIS)

Robinson, G.S.

1986-03-01

In the AUS neutronics code system, the burnup module CHAR solves the nuclide depletion equations by an analytic technique in a number of spatial zones. CHAR is usually used as one component of a lattice burnup calculation but contains features which also make it suitable for some global burnup calculations. BURNMAC is a simple accounting module based on the assumption that cross sections for a rector zone depend only on irradiation. BURNMAC is used as one component of a global calculation in which burnup is achieved by interpolation in the cross sections produced from a previous lattice calculation

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.

Investigation of char strength and expansion properties of an intumescent coating exposed to rapid heating rates

DEFF Research Database (Denmark)

Nørgaard, Kristian Petersen; Dam-Johansen, Kim; Català, Pere

2013-01-01

, char properties, measured at room temperature, were dependent on the preceding storage conditions (in air or in a desiccator). The char was found to have the highest mechanical strength against compression in the outer crust facing the heat source. For thin (147μm) free coating films, a tendency...... with respect to the mechanical resistance against compression, degree of expansion, and residual mass fraction. Experimental results show that when using this type of shock heating, the mechanical resistance of the char against compression cannot meaningfully be correlated to the expansion factor. In addition...

Which kind of aromatic structures are produced during biomass charring? New insights provided by modern solid-state NMR spectroscopy

Science.gov (United States)

Knicker, Heike; Paneque-Carmona, Marina; Velasco-Molina, Marta; de la Rosa, José Maria; León-Ovelar, Laura Regina; Fernandez-Boy, Elena

2017-04-01

Intense research on biochar and charcoal of the last years has revealed that depending on the production conditions, the chemical and physical characteristics of their aromatic network can greatly vary. Since such variations are determining the behavior and stability of charred material in soils, a better understanding of the structural changes occurring during their heating and the impact of those changes on their function is needed. One method to characterize pyrogenic organic matter (PyOM) represents solid-state 13C NMR spectroscopy applying the cross polarization (CP) magic angle spinning technique (MAS). A drawback of this technique is that the quantification of NMR spectra of samples with highly condensed and proton-depleted structures is assumed to be bias. Typical samples with such attributes are charcoals produced at temperatures above 700°C under pyrolytic conditions. Commonly their high condensation degree leads to graphenic structures that are not only reducing the CP efficiency but create also a conductive lattice which acts as a shield and prevents the entering of the excitation pulse into the sample during the NMR experiments. Since the latter can damage the NMR probe and in the most cases the obtained NMR spectra show only one broad signal assignable to aromatic C, this technique is rarely applied for characterizing high temperature chars or soot. As a consequence, a more detailed knowledge of the nature of the aromatic ring systems is still missing. The latter is also true for the aromatic domains of PyOM produced at lower temperatures, since older NMR instruments operating at low magnetic fields deliver solid-state 13C NMR spectra with low resolution which turns a more detailed analysis of the aromatic chemical shift region into a challenging task. In order to overcome this disadvantages, modern NMR spectroscopy offers not only instruments with greatly improved resolution but also special pulse sequences for NMR experiments which allow a more

Fundamental mechanisms for conversion of volatiles in biomass and waste combustion. Final report

Energy Technology Data Exchange (ETDEWEB)

Glarborg, P.; Hindiyarti, L.; Marshall, P.; Livbjerg, H.; Dagaut, P.; Jensen, Anker; Frandsen, Flemming

2007-03-15

This project deals with the volatile oxidation chemistry in biomass and waste fired systems, emphasizing reactions important for pollutants emissions (NO{sub x}, SO{sub 2}, HCl, aerosols). The project aims to extend existing models and databases with a number of chemical subsystems that are presently not well understood, but are particularly important in connection with combustion of biomass and waste. The project is divided into 3 tasks. Task 1: Conversion of chlorine, sulfur and alkali gas phase components in combustion of biomass. Task 2: Formation mechanisms for NO{sub x} in the freeboard of grate combustion of biomass. Task 3: Oxidation mechanisms for oxygenated hydrocarbons in the volatiles from pyrolysis of biomass. (au)

Low-NO{sub x}, wood chip combustion

Energy Technology Data Exchange (ETDEWEB)

Saastamoinen, J.; Oravainen, H.; Haemaelaeinen, J.; Paakkinen, K. [VTT Energy, Jyvaeskylae (Finland)

1997-10-01

The regulations for nitrogen oxide emissions vary in different countries, but the general trend in the future will probably be that the emissions limits will be lowered also for wood combustion plants, which are small or medium size units. Thus, the development of wood chip burning furnaces (grate furnaces, fluidized bed combustors, stoker furnaces) with lower nitrogen oxide emissions, is important. The wood used in the combustor, its particle size, moisture and fuel properties (nitrogen content) affect the nitrogen emissions. The nitrogen oxide release is also much affected by the design and operation of the combustor (air staging, fuel air preheat, flue gas circulation, air to fuel mass ratio). The fate of nitrogen compounds originally in the virgin wood depends much on the design of the combustor system and by proper planning it is possible to reduce the emission of nitrogen oxides. Basic knowledge of the release of nitrogen compounds from single wood particles is attained. The release of gaseous nitrogen compounds from wood particles during pyrolysis and combustion is studied experimentally and by modelling. Nitrogen release is studied experimentally by two ways, by analysing the gas and by quenching the particle and analysing the char residue. Formation of nitrogen oxide emissions in a fuel bed is studied by modelling and by combustion experiments with a pot furnace. This research gives general information of nitrogen oxide formation in wood bunting especially in fixed beds. The development of a horizontal stoker burner for wood chips with low emissions is the practical aim of the research. (orig.)

Quantitative Analysis of Graphene Sheet Content in Wood Char Powders during Catalytic Pyrolysis

Institute of Scientific and Technical Information of China (English)

Yan-Jia Liou; Wu-Jang Huang

2013-01-01

The quantitative characterization of the graphene sheet content in carbon-containing materials is arguable and has not yet been developed.The authors report on a feasible method to characterize graphene sheet content quantitatively in pyrolized carbon materials using an X-ray diffraction (XRD) spectrometer.A direct carbonation at 300 ℃ followed by catalytic pyrolysis (heat-treatment temperature was set at 700-1400 ℃)under a vacuum condition was used for turning wood waste into pyrolized wood char powders.The graphene content in the samples was calculated through an analysis of full width at half maximum (FWHM) of the carbon (100) crystal plane at around 42°-43° in XRD.Results showed that the FWHM and the calculated graphene sheet content of pyrolized wood char powders depended on the heat-treatment temperature,and the FWHM of wood char powder with well-developed graphene sheets (100％) was determined to be 5.0.In addition,the trend to 100％ graphene sheet-contained pyrolized carbon powder was obtained at a heattreatment temperature of 2700 ℃.The resistivity of the wood char powder with 100％ graphene sheets was predicted to be 0.01 Ω cm,close to our experimental data of 0.012 and 0.006 Ω cm for commercial graphite and graphene products,respectively.

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

The effect of temperature and heating rate on char properties obtained from solar pyrolysis of beech wood.

Science.gov (United States)

Zeng, Kuo; Minh, Doan Pham; Gauthier, Daniel; Weiss-Hortala, Elsa; Nzihou, Ange; Flamant, Gilles

2015-04-01

Char samples were produced from pyrolysis in a lab-scale solar reactor. The pyrolysis of beech wood was carried out at temperatures ranging from 600 to 2000°C, with heating rates from 5 to 450°C/s. CHNS, scanning electron microscopy analysis, X-ray diffractometry, Brunauer-Emmett-Teller adsorption were employed to investigate the effect of temperature and heating rate on char composition and structure. The results indicated that char structure was more and more ordered with temperature increase and heating rate decrease (higher than 50°C/s). The surface area and pore volume firstly increased with temperature and reached maximum at 1200°C then reduced significantly at 2000°C. Besides, they firstly increased with heating rate and then decreased slightly at heating rate of 450°C/s when final temperature was no lower than 1200°C. Char reactivity measured by TGA analysis was found to correlate with the evolution of char surface area and pore volume with temperature and heating rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Temperature influence on the fast pyrolysis of manure samples: char, bio-oil and gases production

Directory of Open Access Journals (Sweden)

Fernandez-Lopez Maria

2017-01-01

Full Text Available Fast pyrolysis characterization of three dry manure samples was studied using a pyrolyzer. A heating rate of 600°C/s and a holding time of 10 s were selected to reproduce industrial conditions. The effect of the peak pyrolysis temperature (600, 800 and 1000°C on the pyrolysis product yield and composition was evaluated. Char and bio-oil were gravimetrically quantified. Scanning electron microscopy (SEM was used to analyse the char structure. H2, CH4, CO and CO2 were measured by means of gas chromatography (GC. A decrease in the char yield and an increase of the gas yield were observed when temperature increased. From 800°C on, it was observed that the char yield of samples Dig R and SW were constant, which indicated that the primary devolatilization reactions stopped. This fact was also corroborated by GC analysis. The bio-oil yield slightly increased with temperature, showing a maximum of 20.7 and 27.8 wt.% for samples Pre and SW, respectively, whereas sample Dig R showed a maximum yield of 16.5 wt.% at 800°C. CO2 and CO were the main released gases whereas H2 and CH4 production increased with temperature. Finally, an increase of char porosity was observed with temperature.

Annual Report: Advanced Combustion (30 September 2012)

Energy Technology Data Exchange (ETDEWEB)

Hawk, Jeffrey [NETL; Richards, George

2012-09-30

The Advanced Combustion Project addresses fundamental issues of fire-side and steam-side corrosion and materials performance in oxy-fuel combustion environments and provides an integrated approach into understanding the environmental and mechanical behavior such that environmental degradation can be ameliorated and long-term microstructural stability, and thus, mechanical performance can lead to longer lasting components and extended power plant life. The technical tasks of this effort are Oxy-combustion Environment Characterization, Alloy Modeling and Life Prediction, and Alloy Manufacturing and Process Development.

Heat Transfer in a Fixed Biomass Char Bed

DEFF Research Database (Denmark)

Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Glarborg, P.

2002-01-01

A thermal conductivity model based on the Yagi and Kunii model together with a bed model was developed to describe the thermal conductivity of a straw char bed. The bed model describes the relationship between the distance between particles and the external porosity. To verify the model, thermal ...

Changes of wood anatomical characters of selected species of Araucaria- during artificial charring - implications for palaeontology

Directory of Open Access Journals (Sweden)

Isa Carla Osterkamp

2017-11-01

Full Text Available ABSTRACT Charcoal is widely accepted as evidence of the occurrence of palaeo-wildfire. Although fossil charcoal remains have been used in many studies, investigation into the anatomical changes occurring during charring are few. The present study analyses changes in selected anatomical characters during artificial charring of modern wood of three species of the genus Araucaria (i.e. Araucaria angustifolia, Araucaria bidwillii and Araucaria columnaris. Wood samples of the studied species was charred under controlled conditions at varying temperatures. Measurements of anatomical features of uncharred wood and artificial charcoal were statistically analysed. The anatomical changes were statistically correlated with charring temperatures and most of the parameters showed marked decreases with increasing charring temperature. Compared to the intrinsic variability in anatomical features, both within and between growth rings of an individual plant, the changes induced by temperature account only for a comparatively small percentage of the observed variability. Regarding Araucaria charcoal, it seems possible that at least general taxonomic and palaeoenvironmental implications can be drawn from such material. However, it is not clear so far whether these results and interpretations based on only three taxa, can be generalized for the entire family and anatomically similar fossil taxa or not.

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

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

Temperature induced development of porous structure of bituminous coal chars at high pressure

Directory of Open Access Journals (Sweden)

Natalia Howaniec

2016-01-01

Full Text Available The porous structure of chars affects their reactivity in gasification, having an impact on the course and product distribution of the process. The shape, size and connections between pores determine the mechanical properties of chars, as well as heat and mass transport in thermochemical processing. In the study the combined effects of temperature in the range of 973–1273 °K and elevated pressure of 3 MPa on the development of porous structure of bituminous coal chars were investigated. Relatively low heating rate and long residence time characteristic for the in-situ coal conversion were applied. The increase in the temperature to 1173 °K under pressurized conditions resulted in the enhancement of porous structure development reflected in the values of the specific surface area, total pore volume, micropore area and volume, as well as ratio of the micropore volume to the total pore volume. These effects were attributed to the enhanced vaporization and devolatilization, as well as swelling behavior along the increase of temperature and under high pressure, followed by a collapse of pores over certain temperature value. This proves the strong dependence of the porous structure of chars not only on the pyrolysis process conditions but also on the physical and chemical properties of the parent fuel.

Are forestation, bio-char and landfilled biomass adequate offsets for the climate effects of burning fossil fuels?

International Nuclear Information System (INIS)

Reijnders, L.

2009-01-01

Forestation and landfilling purpose-grown biomass are not adequate offsets for the CO 2 emission from burning fossil fuels. Their permanence is insufficiently guaranteed and landfilling purpose-grown biomass may even be counterproductive. As to permanence, bio-char may do better than forests or landfilled biomass, but there are major uncertainties about net greenhouse gas emissions linked to the bio-char life cycle, which necessitate suspension of judgement about the adequacy of bio-char addition to soils as an offset for CO 2 emissions from burning fossil fuels.

Synthesis of palm oil empty fruit bunch magnetic pyrolytic char impregnating with FeCl3 by microwave heating technique

International Nuclear Information System (INIS)

Mubarak, N.M.; Kundu, A.; Sahu, J.N.; Abdullah, E.C.; Jayakumar, N.S.

2014-01-01

Empty fruit bunch (EFB) is one of the most abundant residues of the Palm oil mill industry in Malaysia. The novel magnetic bio-char was synthesized by single stage microwave heating technique, using EFB in the presence of ferric chloride hexahydrate. The effect of microwave powers, radiation time and impregnation ratio (IR) of ferric chloride hexahydrate to biomass were studied. Also the process parameters such as microwave powers, radiation times and IR were optimized using response surface method. The statistical analysis revealed that the optimum conditions for the high porosity magnetic bio-char production were at 900 W microwave power, 20 min radiation time and 0.5 (FeCl 3 : biomass) impregnation ratio. These newly produced magnetic bio-char have a high surface area of 890 m 2  g −1 and that leads to highly efficient in the removal of methylene blue (MB) with an efficiency of 99.9% from aqueous solution with a maximum adsorption capacity of 265 mg g −1 . - Highlights: • Magnetic bio-char production using discarded material EFB with chemical activation. • Single stage synthesis of magnetic bioc-har via microwave heating was narrated. • Effect of each process parameters on synthesis of magnetic bio-char was elaborated. • Magnetic bio-char has high surface area, high porosity and high adsorption capacity. • Novel magnetic bio-char adds new dimension to the materials as an adsorbent

Properties and Beneficial Uses of (BioChars, with Special Attention to Products from Sewage Sludge Pyrolysis

Directory of Open Access Journals (Sweden)

Arianna Callegari

2018-03-01

Full Text Available Residual sludge disposal costs may constitute up to, and sometimes above, 50% of the total cost of operation of a Wastewater Treatment Plant (WWTP and contribute approximately 40% of the total greenhouse gas (GHG emissions associated with its operation. Traditionally, wastewater sludges are processed for: (a reduction of total weight and volume to facilitate their transfer and subsequent treatments; (b stabilization of contained organic material and destruction of pathogenic microorganisms, elimination of noxious odors, and reduction of putrefaction potential and, at an increasing degree; (c value addition by developing economically viable recovery of energy and residual constituents. Among several other processes, pyrolysis of sludge biomass is being experimented with by some researchers. From the process, oil with composition not dissimilar to that of biodiesels, syngas, and a solid residue can be obtained. While the advantage of obtaining sludge-derived liquid and gaseous fuels is obvious to most, the solid residue from the process, or char (also indicated as biochar by many, may also have several useful, initially unexpected applications. Recently, the char fraction is getting attention from the scientific community due to its potential to improve agricultural soils’ productivity, remediate contaminated soils, and supposed, possible mitigation effects on climate change. This paper first discusses sludge-pyrolysis-derived char production fundamentals (including relationships between char, bio-oil, and syngas fractions in different process operating conditions, general char properties, and possible beneficial uses. Then, based on current authors’ experiments with microwave-assisted sludge pyrolysis aimed at maximization of liquid fuel extraction, evaluate specific produced char characteristics and production to define its properties and most appropriate beneficial use applications in this type of setting.

Structural features of resorcinol–formaldehyde resin chars and interfacial behavior of water co-adsorbed with low-molecular weight organics

International Nuclear Information System (INIS)

Gun’ko, Vladimir M.; Bogatyrov, Viktor M.; Turov, Vladimir V.; Leboda, Roman; Skubiszewska-Zięba, Jadwiga; Urubkov, Iliya V.

2013-01-01

Products of resorcinol–formaldehyde resin carbonization (chars) are characterized by different morphology (particle shape and sizes) and texture (specific surface area, pore volume and pore size distribution) depending on water content during resin polymerization. At a low amount of water (C w = 37.8 wt.%) during synthesis resulting in strongly cross-linked polymers, carbonization gives nonporous particles. An increase in the water content to 62.7 wt.% results in a nano/mesoporous char, but if C w = 73.3 wt.%, a char is purely nanoporous. Despite these textural differences, the Raman spectra of all the chars are similar because of the similarity in the structure of their carbon sheets with a significant contribution of sp 3 C atoms. However, the difference in the spatial organization of the carbon sheet stacks in the particles results in the significant differences in the textural and morphological characteristics and in the adsorption properties of chars with respect to water, methane, benzene, hydrogen, methylene chloride, and dimethylsulfoxide.

Structural features of resorcinol–formaldehyde resin chars and interfacial behavior of water co-adsorbed with low-molecular weight organics

Energy Technology Data Exchange (ETDEWEB)

Gun’ko, Vladimir M., E-mail: vlad_gunko@ukr.net [Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kyiv (Ukraine); Bogatyrov, Viktor M.; Turov, Vladimir V. [Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kyiv (Ukraine); Leboda, Roman; Skubiszewska-Zięba, Jadwiga [Faculty of Chemistry, Maria Curie-Skłodowska University, 20031 Lublin (Poland); Urubkov, Iliya V. [Kurdyumov Institute of Metal Physics, 36 Vernadsky Boulevard, 03142 Kyiv (Ukraine)

2013-10-15

Products of resorcinol–formaldehyde resin carbonization (chars) are characterized by different morphology (particle shape and sizes) and texture (specific surface area, pore volume and pore size distribution) depending on water content during resin polymerization. At a low amount of water (C{sub w} = 37.8 wt.%) during synthesis resulting in strongly cross-linked polymers, carbonization gives nonporous particles. An increase in the water content to 62.7 wt.% results in a nano/mesoporous char, but if C{sub w} = 73.3 wt.%, a char is purely nanoporous. Despite these textural differences, the Raman spectra of all the chars are similar because of the similarity in the structure of their carbon sheets with a significant contribution of sp{sup 3} C atoms. However, the difference in the spatial organization of the carbon sheet stacks in the particles results in the significant differences in the textural and morphological characteristics and in the adsorption properties of chars with respect to water, methane, benzene, hydrogen, methylene chloride, and dimethylsulfoxide.

Anadromous char as an alternate food choice to marine animals: A synthesis of Hg concentrations, population features and other influencing factors

Energy Technology Data Exchange (ETDEWEB)

Evans, Marlene S., E-mail: marlene.evans@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 11 Innovation Blvd., Saskatoon SK S7N 3H5 (Canada); Muir, Derek C.G. [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Rd., Burlington, ON L7R 4A6 (Canada); Keating, Jonathan [Environment Canada, Water Science and Technology Directorate, 11 Innovation Blvd., Saskatoon SK S7N 3H5 (Canada); Wang, Xiaowa [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Rd., Burlington, ON L7R 4A6 (Canada)

2015-03-15

This study was conducted to confirm sporadic measurements made over the late 1970s to the early 1990s which determined that mercury (Hg) concentrations were low in anadromous char across Arctic and subarctic Canada including northern Québec and Labrador. Over 2004–2013, anadromous char populations across northern Canada were investigated at 20 sites for Hg concentrations and life history characteristics. Hg concentrations were extremely low in anadromous char muscle, typically < 0.05 μg/g (wet weight) and, at each location, generally increased with fish length, age and nitrogen isotope (δ{sup 15}N) ratio and decreased with condition factor and %lipid; correlations with carbon isotope (δ{sup 13}C) ratio were inconsistent. Location and year were significant variables influencing Hg concentrations over the study area; longitude and latitude also were significant influencing variables. Char length, weight, age, condition factor and lipid content explained additional variance. A tendency towards higher Hg concentrations with increasing latitude may be partially related to decreasing growth of char towards the north. However, Hg concentrations in char were positively correlated with growth rates suggesting that Hg concentrations in char also were higher in the more productive study areas, including to the west where mainland riverine inputs of terrestrial carbon, nutrients, and Hg were greater. The data base for assessing time trends in char was limited by the small number of years investigated at most locations, variable fish size across years, small sample size, etc. Where temporal trends were detected, they were of increase on the long term (1970s, 1980s or early 1990s to the present) but of decrease on the short term (early 2000s to present) with Nain (Labrador) showing the converse pattern. Higher Hg concentrations were also related to lower condition factor and cooler springs. Hg concentrations in anadromous char are compared with other terrestrial, aquatic

Anadromous char as an alternate food choice to marine animals: A synthesis of Hg concentrations, population features and other influencing factors

International Nuclear Information System (INIS)

Evans, Marlene S.; Muir, Derek C.G.; Keating, Jonathan; Wang, Xiaowa

2015-01-01

This study was conducted to confirm sporadic measurements made over the late 1970s to the early 1990s which determined that mercury (Hg) concentrations were low in anadromous char across Arctic and subarctic Canada including northern Québec and Labrador. Over 2004–2013, anadromous char populations across northern Canada were investigated at 20 sites for Hg concentrations and life history characteristics. Hg concentrations were extremely low in anadromous char muscle, typically < 0.05 μg/g (wet weight) and, at each location, generally increased with fish length, age and nitrogen isotope (δ 15 N) ratio and decreased with condition factor and %lipid; correlations with carbon isotope (δ 13 C) ratio were inconsistent. Location and year were significant variables influencing Hg concentrations over the study area; longitude and latitude also were significant influencing variables. Char length, weight, age, condition factor and lipid content explained additional variance. A tendency towards higher Hg concentrations with increasing latitude may be partially related to decreasing growth of char towards the north. However, Hg concentrations in char were positively correlated with growth rates suggesting that Hg concentrations in char also were higher in the more productive study areas, including to the west where mainland riverine inputs of terrestrial carbon, nutrients, and Hg were greater. The data base for assessing time trends in char was limited by the small number of years investigated at most locations, variable fish size across years, small sample size, etc. Where temporal trends were detected, they were of increase on the long term (1970s, 1980s or early 1990s to the present) but of decrease on the short term (early 2000s to present) with Nain (Labrador) showing the converse pattern. Higher Hg concentrations were also related to lower condition factor and cooler springs. Hg concentrations in anadromous char are compared with other terrestrial, aquatic and

Combustion properties of kraft black liquors; Ligniinifraktion vaikutus mustalipeaen poltto-ominaisuuksiin

Energy Technology Data Exchange (ETDEWEB)

Alen, R.; Rantanen, K.; Ekman, J.; Malkavaara, P. [Jyvaeskylae Univ. (Finland)

1996-12-01

The aim of this investigation was to find relationships between the structure of the dissolved lignin and the combustion properties (pyrolysis time, char burning time, and swelling) of softwood and hardwood kraft black liquors. In this conjunction, pine and birch chips, as well as their two mixtures (the mass ratios of pine chips to birch chips were 80:20 and 60:40), were delignified by conventional kraft pulping. In each cook series, a liquor sample was withdrawn at certain time intervals to obtain liquor samples with different chemical composition. The black liquors obtained were analyzed with respect to the content of lignin and `lignin monomers`, but also the molecular-mass distribution and the mass average molecular mass of lignin were made. In addition, the dissolved lignin was characterized by NMR spectroscopy and elemental analysis. Further data on the chemical structures of lignin in black liquors were obtained by identifying various degradation products formed from this material during oxidative (CuO oxidation) and pyrolytic treatments. Several correlations between the `structural parameters` of the dissolved lignin and the combustion properties of black liquor were found. These correlations were significant especially in the case of pine cook. The results revealed many findings which are, together with the earlier data, useful for a better understanding of the thermochemical behavior of different kraft black liquors during combustion in a recovery furnace. (author)

Effect of fire residues (ash and char) on microbial activity, respiration and methanogenesis in three subtropical wetland soils

Science.gov (United States)

Medvedeff, C.; Hogue, B.; Inglett, P.

2011-12-01

Prescribed fire is a common restoration and maintenance technique in the southern United States. Prescribed burns coupled with frequent natural fires in South Florida can have devastating effects on ecosystem function. To determine the effect fire residues have on carbon biogeochemical cycling litter material was obtained from two restored and one native marl wetland in Everglades National Park and manipulated in a laboratory setting to produce ash and vegetation derived char. Based on vegetation biomass removal pre and post fire (insitu) appropriate aliquots of each fire residue was added to experimental microcosms as a soil amendment. Soil enzymes (β-glucosidase, cellobiohydrolase, phosphatase, bis-phosphate and leucine amino peptidase), aerobic and anaerobic respiration (CO2) potentials, extractable C and methanogenesis were measured over a 25 day period. Regardless of site C enzymes responded to both amendments within 5 days of addition. Similarly amended soil contained more extractable carbon in the reference and one of the restored sites. In the restored sites ash and char inhibited methanogenesis, had no effect on anaerobic CO2 potentials, but stimulated aerobic respiration after ten days. In contrast, within the first ten days phosphatase enzyme activity was lower in the ash treatment when compared to the control treatment and stimulation of aerobic respiration was observed in both treatment soils. After ten days ash stimulated methanogenic processing while suppressing anaerobic CO2 production suggesting methanogens in this ecosystem may be dependant on usable carbon substrates derived from aerobic microbial processing. This study illustrates the variable response of C parameters to complete and incomplete combusted materials produced from both prescribed and natural fires with particular importance to fire adapted ecosystems.

Effects of Bio-char on Soil Microbes in Herbicide Residual Soils

Directory of Open Access Journals (Sweden)

WANG Gen-lin

2015-10-01

Full Text Available Effects of biological carbon (bio-char on soil microbial community were studied by pot experiments simulating long residual herbicide residues in soil environment, which clarifed the improvement of biochar and its structural properties on soil microenvironment. The results showed that fungi and actinomycetes had the same effect tendency within 0~0.72 mg·kg-1 in clomazone residue which increased the role of stimulation with crop growth process prolonged, especially in high residue treatment, but strong inhibitory effect on bacteria community was occured early which returned to normal until sugar beet growth to fiftieth day. Soil fungi community decreased with bio-char adding, but had no significant difference with the control. When clomazone residue in soil was below 0.24 mg·kg-1, soil actinomycetes community was higher than control without bio-char, bacteria increased first and then reduced after adding carbon as below 0.12 mg·kg-1. Biochar was ‘deep hole’ structure containing C, O, S and other elements. The results showed that a certain concentration clomazone residue in soil would stimulate soil fungi and actinomycetes to grow. After adding the biochar, the inhibition effect of high herbicides residual on bacterial would be alleviated.

Anadromous char as an alternate food choice to marine animals: a synthesis of Hg concentrations, population features and other influencing factors.

Science.gov (United States)

Evans, Marlene S; Muir, Derek C G; Keating, Jonathan; Wang, Xiaowa

2015-03-15

This study was conducted to confirm sporadic measurements made over the late 1970s to the early 1990 s which determined that mercury (Hg) concentrations were low in anadromous char across Arctic and subarctic Canada including northern Québec and Labrador. Over 2004-2013, anadromous char populations across northern Canada were investigated at 20 sites for Hg concentrations and life history characteristics. Hg concentrations were extremely low in anadromous char muscle, typically Hg concentrations over the study area; longitude and latitude also were significant influencing variables. Char length, weight, age, condition factor and lipid content explained additional variance. A tendency towards higher Hg concentrations with increasing latitude may be partially related to decreasing growth of char towards the north. However, Hg concentrations in char were positively correlated with growth rates suggesting that Hg concentrations in char also were higher in the more productive study areas, including to the west where mainland riverine inputs of terrestrial carbon, nutrients, and Hg were greater. The data base for assessing time trends in char was limited by the small number of years investigated at most locations, variable fish size across years, small sample size, etc. Where temporal trends were detected, they were of increase on the long term (1970s, 1980s or early 1990 s to the present) but of decrease on the short term (early 2000s to present) with Nain (Labrador) showing the converse pattern. Higher Hg concentrations were also related to lower condition factor and cooler springs. Hg concentrations in anadromous char are compared with other terrestrial, aquatic and marine vertebrates in traditional diets. The known information on anadromous char is reviewed including population features, habitat, and harvests. Future Hg trend monitoring should focus on specific locations and harvest areas within these areas to better assess trends and influencing factors. Crown

Gasification of brown coal and char with carbon dioxide in the presence of finely dispersed iron catalysts

Energy Technology Data Exchange (ETDEWEB)

Asami, K.; Sears, P.; Furimsky, E.; Ohtsuka, Y. [Osaka City University, Osaka (Japan). Dept. of Applied Chemistry

1996-05-01

Gasification of brown coal and char with CO{sub 2} using iron catalysts precipitated from an aqueous solution of FeCl{sub 3} has been studied. When the pyrolyzed char is gasified in the temperature-programmed mode, the presence of the iron can lower the temperature giving the maximal rate of CO formation by 130-160 K, a larger lowering being observed at a higher loading in the range of {le} 3 wt% Fe. The specific rates of the isothermal gasification iron-bearing chars at 1173 and 1223 K increase with increasing char conversion, resulting in complete gasification within a short reaction time. Comparison of the initial rates of uncatalyzed and catalyzed gasification reveals that iron addition can lower the reaction temperature by 120 K. Moessbauer spectra show that the precipitation iron exists as fine FeOOH particles, which are reduced mainly to Fe{sub 3}C on charring at 1123 K. Most of the Fe{sub 3}C is transformed into {alpha}-Fe and {gamma}-Fe at the initial stage of gasification, and subsequently these species are oxidized to FeO and Fe{sub 3}O{sub 4}. The changes during gasification are discussed in terms of solid-gas and solid-solid reactions. 23 refs., 10 figs.

The mechanism of char ignition in fluidized bed combustors

NARCIS (Netherlands)

Siemons, R.V.

1987-01-01

Knowledge about ignition processes of coal in fluidized beds is of importance for the start-up and dynamic control of these combustors. Initial experiments in a transparent fluidized bed scale model showed the existence of a considerable induction period for the ignition of char, especially at low

Effect of chemical modification on reduction and sorptive properties of chars from hydropyrolysis of coal

Energy Technology Data Exchange (ETDEWEB)

Stanczyk, K.; Miga, K.; Fabis, G.; Jastrzab, K. [Polskiej Akademii Nauk, Gliwice (Poland)

1998-01-01

Hydropyrolysis of bituminous coal and lignite as way of synthesis of adsorbents has been applied. Chemical modification of chars based on simultaneous carbonization of coal and plastics containing sulfur and nitrogen has been carried out. It was stated that modified chars exhibit better reduction and sorptive properties than non-modified and that modified adsorbents made of lignite exceed commercial ones. 7 refs., 4 figs., 3 tabs.

Active carbons from low temperature conversion chars

International Nuclear Information System (INIS)

Adebowale, K.O.; Bayer, E.

2002-05-01

Hulls obtained from the fruits of five tropical biomass have been subjected to low temperature conversion process and their chars activated by partial physical gasification to produce active carbons. The biomass are T. catappa, B. nitida, L leucophylla, D. regia and O. martiana. The bulk densities of the samples ranged from 0.32 g.cm 3 to 0.52 g.cm 3 . Out of the samples T. catappa recorded the highest cellulose content (41.9 g.100g -1 ), while O. martiana contained the highest lignin content (40.7 g.100g -1 ). The ash of the samples were low (0.5 - 4.4%). The percentage of char obtained after conversion were high (33.7% - 38.6%). Active carbons obtained from T. catappa, D. regia and O. martiana, recorded high methylene blue numbers and iodine values. They also displayed good micro- and mesostructural characteristics. Micropore volume (V micro ) was between 0.33cm 3 .g -1 - 0.40cm 3 .g -1 , while the mesopore volume(V meso ) was between 0.05 cm 3 .g -1 - 0.07 cm 3 .g -1 . The BET specific surface exceeds 1000 m 2 .g -1 . All these values compared favourably with high grade commercial active carbons. (author)

The efficacy of high-throughput sequencing and target enrichment on charred archaeobotanical remains

DEFF Research Database (Denmark)

Nistelberger, H. M.; Smith, O.; Wales, Nathan

2016-01-01

. It has been suggested that high-throughput sequencing (HTS) technologies coupled with DNA enrichment techniques may overcome some of these limitations. Here we report the findings of HTS and target enrichment on four important archaeological crops (barley, grape, maize and rice) performed in three...... lightly-charred maize cob. Even with target enrichment, this sample failed to yield adequate data required to address fundamental questions in archaeology and biology. We further reanalysed part of an existing dataset on charred plant material, and found all purported endogenous DNA sequences were likely...

Synergistic effect on thermal behavior and char morphology analysis during co-pyrolysis of paulownia wood blended with different plastics waste

International Nuclear Information System (INIS)

Chen, Lin; Wang, Shuzhong; Meng, Haiyu; Wu, Zhiqiang; Zhao, Jun

2017-01-01

Highlights: • Positive synergistic effect on volatiles yield during co-pyrolysis of PAW and PP. • Higher char yields than predicated value during PAW/PVC and PAW/PET blends pyrolysis. • Co-pyrolysis of PAW and plastics reduced the mean activation energy of the blends. • The plastics affected the surface morphology of co-pyrolysis chars significantly. - Abstract: Thermal behavior of Paulownia wood (PAW), model plastics (polypropylene, polyvinyl chloride and polyethylene terephthalate, abbreviated as PP, PVC and PET) and their mixtures during pyrolysis process were studied through thermogravimetric analyzer. Scanning electron microscopy technology (SEM) and fractal theory were applied to evaluate the surface morphology of pyrolysis chars. This study found that PP showed synergistic effect on PAW pyrolysis with more volatiles release than predicated value, and the maximum volatiles yield exhibited with 25% PAW blending ratio. However, higher char yields were observed compared with the predicted values during co-pyrolysis process of PAW blends with PVC or PET, and the maximum char yields were obtained under the PAW blending ratio of 75% and 25% respectively. An evident decline in mean activation energy was found during co-pyrolysis of the PAW blending with plastics. The minimum values of mean activation energy for the PAW/PP, PAW/PVC and PAW/PET were gained when the PAW blending ratio were 75%, 50% and 75% respectively. Quantitative information about surface topography of pyrolysis chars were obtained by fractal analysis of the SEM microphotograph. The fractal dimension of residual chars from PAW/PP blends increased from 1.75 to 1.84 as increasing the ratio of PP from 25% to 75%, indicating that PP addition promoted the nonuniformity of the co-pyrolysis chars. The surface morphology of residual chars from PAW/PET and PAW/PVC blends showed a contrary tendency, and the minimum values of fractal dimension were respectively 1.62 and 1.61 under 25% PAW blending

Towards User-Friendly Spelling with an Auditory Brain-Computer Interface: The CharStreamer Paradigm

Science.gov (United States)

Höhne, Johannes; Tangermann, Michael

2014-01-01

Realizing the decoding of brain signals into control commands, brain-computer interfaces (BCI) aim to establish an alternative communication pathway for locked-in patients. In contrast to most visual BCI approaches which use event-related potentials (ERP) of the electroencephalogram, auditory BCI systems are challenged with ERP responses, which are less class-discriminant between attended and unattended stimuli. Furthermore, these auditory approaches have more complex interfaces which imposes a substantial workload on their users. Aiming for a maximally user-friendly spelling interface, this study introduces a novel auditory paradigm: “CharStreamer”. The speller can be used with an instruction as simple as “please attend to what you want to spell”. The stimuli of CharStreamer comprise 30 spoken sounds of letters and actions. As each of them is represented by the sound of itself and not by an artificial substitute, it can be selected in a one-step procedure. The mental mapping effort (sound stimuli to actions) is thus minimized. Usability is further accounted for by an alphabetical stimulus presentation: contrary to random presentation orders, the user can foresee the presentation time of the target letter sound. Healthy, normal hearing users (n = 10) of the CharStreamer paradigm displayed ERP responses that systematically differed between target and non-target sounds. Class-discriminant features, however, varied individually from the typical N1-P2 complex and P3 ERP components found in control conditions with random sequences. To fully exploit the sequential presentation structure of CharStreamer, novel data analysis approaches and classification methods were introduced. The results of online spelling tests showed that a competitive spelling speed can be achieved with CharStreamer. With respect to user rating, it clearly outperforms a control setup with random presentation sequences. PMID:24886978

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...

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.

Synthesis and characterization of poly (dihydroxybiphenyl borate) with high char yield for high-performance thermosetting resins

Science.gov (United States)

Wang, Shujuan; Xing, Xiaolong; Li, Jian; Jing, Xinli

2018-01-01

The objective of the current work is to synthesize novel boron-containing polymers with excellent thermal resistance, and reveal the structure and the reason for the high char yield. Thus, poly (dihydroxybiphenyl borate) (PDDB) with a more rigid molecular chain, was successfully synthesized using 4,4‧-dihydroxybiphenyl and boric acid. Structural characterizations of the prepared PDDB were performed via NMR, FTIR, XPS, and XRD analyses. The results reveal that PDDB consists of aromatic, Phsbnd Osbnd B and Bsbnd Osbnd B structures as well as a small number of boron hydroxyl and phenolic hydroxyl groups. PDDB shows good solubility in strong polar solvents, which is of great importance for the modification of thermosetting resins. TGA combined with DSC were employed to evaluate the thermal properties of PDDB, and increases in the glass transition temperature (Tg) and char yield were observed with increased boron content. Tg and char yield of PDDB (800 °C, nitrogen atmosphere) reached up to 219 °C and 66.5%, respectively. PDDB was extensively characterized during pyrolysis to reveal the high char yield of PDDB. As briefly discussed, the boron oxide and boron carbide that formed during pyrolysis play a crucial role in the high char yield of PDDB, which reduces the release of volatile carbon dioxide and carbon. This research suggests that PDDB has great potential as a novel modified agent for the improvement of the comprehensive performance of thermosetting resins to broaden their applicability in the field of advanced composites.

Effect of cuprous oxide with different sizes on thermal and combustion behaviors of unsaturated polyester resin.

Science.gov (United States)

Hou, Yanbei; Hu, Weizhao; Gui, Zhou; Hu, Yuan

2017-07-15

Cuprous oxide (Cu 2 O) as an effective catalyst has been applied to enhance the fire safety of unsaturated polyester resin (UPR), but the particle size influence on combustion behaviors has not been previously reported. Herein, the UPR/Cu 2 O composites (metal oxide particles with average particle-size of 10, 100, and 200nm) were successfully synthesized by thermosetting process. The effects of Cu 2 O with different sizes on thermostability and combustion behaviors of UPR were characterized by TGA, MCC, TG-IR, FTIR, and SSTF. The results revel that the addition of Cu 2 O contributes to sufficient decomposition of oxygen-containing compounds, which is beneficial to the release of nontoxic compounds. The smallest-sized Cu 2 O performs the excellent catalytic decomposition effect and promotes the complete combustion of UPR, which benefits the enhancement of fire safety. While the other additives retard pyrolysis process and yield more char residue, and thus the flame retardancy of UPR composites was improved. Therefore, catalysis plays a major role for smaller-sized particles during thermal decomposition of matrix, while flame retarded effect became gradual distinctly for the larger-sized additives. Copyright © 2017 Elsevier B.V. All rights reserved.

Biochemical stability of sewage sludge chars and their impact on soil organic matter of a Mediterranean Cambisol

Science.gov (United States)

Paneque, Marina; María De la Rosa, José; Aragón, Carlos; Kern, Jürgen; Knicker, Heike

2016-04-01

Transformation of sewage sludge (SS) into char achieves sludge hygienisation, which is necessary prior its application into agricultural soils. The pyrolysis of SS increases its stability in a degree which depends on the thermal treatment used. Thus, chars produced by using hydrothermal carbonization are typically more stable than normal soil organic matter (SOM), but less stable than chars from dry pyrolysis (Libra et al., 2011). Addition of highly-recalcitrant SS-chars to soil will likely increase its carbon sequestration potential; however the fertilizing properties of SS may be compromised due to its alteration during the pyrolysis. The main goal of this work was to investigate the biochemical recalcitrance of two 13C-enriched SS-chars once applied in a Mediterranean Cambisol as well as to evaluate their impact on the SOM quality and carbon stability. Thus, we studied the distribution of 13C between plants and soil after the addition of the 13C-enriched chars (2 atm%) to the soil. Therefore, we performed a greenhouse incubation experiment, using a Mediterranean Cambisol as matrix and tested the following treatments: control (soil alone), raw SS, SS-hydrochar, SS-pyrochar. The SS was produced in a pilot-scale waste-water plant and enriched with 13C by the addition of 13C-glucose during the treatment. The amendment was only applied to the upper 2 cm of the soil matrix where it accounted for 5% of its dry weight. Per pot, 25 seeds of Lolium perenne were sowed and incubated under controlled conditions. The biomass production as well as the concentration of 13C in leaves and roots was determined after 1, 2 and 5 months. The partitioning of the 13C between soil and plant and its transformation into bioavailable forms were monitored by stable isotopic mass spectrometry. The 13C-enrichment of the chars allowed the use of solid-state 13C NMR spectroscopy as a means for the detection of chemical alterations of the chars during their aging. Libra J., Ro K., Kammann C

Utilization of oil palm tree residues to produce bio-oil and bio-char via pyrolysis

International Nuclear Information System (INIS)

Abnisa, Faisal; Arami-Niya, Arash; Wan Daud, W.M.A.; Sahu, J.N.; Noor, I.M.

2013-01-01

Highlights: • About 14.72% of the total landmass in Malaysia was used for oil palm plantations. • Oil palm tree residues were pyrolyzed to produce bio-oil and bio-char. • The process was performed at a temperature of 500 °C and reaction time of 60 min. • Characterization of the products was performed. - Abstract: Oil palm tree residues are a rich biomass resource in Malaysia, and it is therefore very important that they be utilized for more beneficial purposes, particularly in the context of the development of biofuels. This paper described the possibility of utilizing oil palm tree residues as biofuels by producing bio-oil and bio-char via pyrolysis. The process was performed in a fixed-bed reactor at a temperature of 500 °C, a nitrogen flow rate of 2 L/min and a reaction time of 60 min. The physical and chemical properties of the products, which are important for biofuel testing, were then characterized. The results showed that the yields of the bio-oil and bio-char obtained from different residues varied within the ranges of 16.58–43.50 wt% and 28.63–36.75 wt%, respectively. The variations in the yields resulted from differences in the relative amounts of cellulose, hemicellulose, lignin, volatiles, fixed carbon, and ash in the samples. The energy density of the bio-char was found to be higher than that of the bio-oil. The highest energy density of the bio-char was obtained from a palm leaf sample (23.32 MJ/kg), while that of the bio-oil was obtained from a frond sample (15.41 MJ/kg)

Bio-oil and bio-char production from corn cobs and stover by fast pyrolysis

International Nuclear Information System (INIS)

Mullen, Charles A.; Boateng, Akwasi A.; Goldberg, Neil M.; Lima, Isabel M.; Laird, David A.; Hicks, Kevin B.

2010-01-01

Bio-oil and bio-char were produced from corn cobs and corn stover (stalks, leaves and husks) by fast pyrolysis using a pilot scale fluidized bed reactor. Yields of 60% (mass/mass) bio-oil (high heating values are ∼20 MJ kg -1 , and densities >1.0 Mg m -3 ) were realized from both corn cobs and from corn stover. The high energy density of bio-oil, ∼20-32 times on a per unit volume basis over the raw corn residues, offers potentially significant savings in transportation costs particularly for a distributed 'farm scale' bio-refinery system. Bio-char yield was 18.9% and 17.0% (mass/mass) from corn cobs and corn stover, respectively. Deploying the bio-char co-product, which contains most of the nutrient minerals from the corn residues, as well as a significant amount of carbon, to the land can enhance soil quality, sequester carbon, and alleviate environmental problems associated with removal of crop residues from fields.

SYNERGISTIC EFFECTS OF NOVOLAC-BASED CHAR FORMER WITH A PHOSPHORUS/NITROGEN-CONTAINING FLAME RETARDANT IN POLYAMIDE 6

Institute of Scientific and Technical Information of China (English)

Wei-cheng Xiong; Li Chen; De-yi Wang; Fei Song; Yu-zhong Wang

2012-01-01

The synergistic effect of phosphorus oxynitride (PON) with a novolac-based char former modified by salification (NA-metal salt) on the flame retardance of polyamide 6 (PA6) was investigated.For this purpose,various flame-retardant PA6 systems were melt-compounded with PON,PON/NA,PON/NA-V2O5 and PON/NA-Fe2O3,and their flame retardance was evaluated by measuring the limiting oxygen index (LOI) values and UL-94 vertical burning ratings.The results showed that,compared with the PA6/PON/NA system,the combination of two char formers (NA-V2O5,NA-Fe2O3) with PON could obviously improve the char formation and flame retardance of PA6.The flame retardance and cone calorimetric analyses showed the stronger synergism as well as the better flame retardant performance of PON/NA-Fe2O3 flame retardant system.The effects of different char formers on the flame retardance and thermal stability of this system were also discussed.

Cd(II) adsorption on various adsorbents obtained from charred biomaterials

International Nuclear Information System (INIS)

Li Zhenze; Katsumi, Takeshi; Imaizumi, Shigeyoshi; Tang Xiaowu; Inui, Toru

2010-01-01

Cadmium could cause severe toxicant impact to living beings and is especially mobile in the environment. Biomass is abundant and effective to adsorb heavy metals, but is easy to be decomposed biologically which affects the reliability of long-run application. Several biomasses were charred with and without additives at temperatures less than 200 deg. C in this study. The prepared adsorbents were further testified to remove Cd(II) from aqueous solution. Equilibrium and kinetic studies were performed in batch conditions. The effect of several experimental parameters on the cadmium adsorption kinetics namely: contact time, initial cadmium concentration, sorbent dose, initial pH of solution and ionic strength was evaluated. Kinetic study confirmed (1) the rapid adsorption of Cd(II) on GC within 10 min and (2) the following gradual intraparticle diffusion inwards the sorbent at neutral pH and outwards at strong acidic solution. The grass char (GC) was selected for further test according to its high adsorption capacity (115.8 mg g -1 ) and affinity (Langmuir type isotherm). The Cd(II) removal efficiency was increased with increasing solution pH while the highest achieved at sorbent dosage 10.0 g L -1 . The ionic strength affects the sorption of Cd(II) on GC to a limited extent whereas calcium resulted in larger competition to the sorption sites than potassium. Spectroscopic investigation revealed the adsorption mechanisms between Cd(II) and surface functional groups involving amine, carboxyl and iron oxide. The long-term stability of the pyrolyzed grass char and the potential application in engineering practices were discussed.

Active carbons from low temperature conversion chars

Energy Technology Data Exchange (ETDEWEB)

Adebowale, K O [Department of Chemistry, University of lbadan, lbadan (Nigeria); Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Bayer, E [Universitaet Tuebingen, Institut fuer Organische Chemie, Forschungstelle Nukleinsaeure- und Peptidchemie, Tuebingen (Germany)

2002-05-01

Hulls obtained from the fruits of five tropical biomass have been subjected to low temperature conversion process and their chars activated by partial physical gasification to produce active carbons. The biomass are T. catappa, B. nitida, L leucophylla, D. regia and O. martiana. The bulk densities of the samples ranged from 0.32 g.cm{sup 3} to 0.52 g.cm{sup 3}. Out of the samples T. catappa recorded the highest cellulose content (41.9 g.100g{sup -1}), while O. martiana contained the highest lignin content (40.7 g.100g{sup -1}). The ash of the samples were low (0.5 - 4.4%). The percentage of char obtained after conversion were high (33.7% - 38.6%). Active carbons obtained from T. catappa, D. regia and O. martiana, recorded high methylene blue numbers and iodine values. They also displayed good micro- and mesostructural characteristics. Micropore volume (V{sub micro}) was between 0.33cm{sup 3}.g{sup -1} - 0.40cm{sup 3}.g{sup -1}, while the mesopore volume(V{sub meso}) was between 0.05 cm{sup 3}.g{sup -1} - 0.07 cm{sup 3}.g{sup -1}. The BET specific surface exceeds 1000 m{sup 2}.g{sup -1}. All these values compared favourably with high grade commercial active carbons. (author)

Cow bones char as a green sorbent for fluorides removal from aqueous solutions: batch and fixed-bed studies.

Science.gov (United States)

Nigri, Elbert M; Cechinel, Maria Alice P; Mayer, Diego A; Mazur, Luciana P; Loureiro, José M; Rocha, Sônia D F; Vilar, Vítor J P

2017-01-01

Cow bone char was investigated as sorbent for the defluoridation of aqueous solutions. The cow bone char was characterized in terms of its morphology, chemical composition, and functional groups present on the bone char surface using different analytical techniques: SEM, EDS, N 2 -BET method, and FTIR. Batch equilibrium studies were performed for the bone chars prepared using different procedures. The highest sorption capacities for fluoride were obtained for the acid washed (q = 6.2 ± 0.5 mg/g) and Al-doped (q = 6.4 ± 0.3 mg/g) bone chars. Langmuir and Freundlich models fitted well the equilibrium sorption data. Fluoride removal rate in batch system is fast in the first 5 h, decreasing after this time until achieving equilibrium due to pore diffusion. The presence of carbonate and bicarbonate ions in the aqueous solution contributes to a decrease of the fluoride sorption capacity of the bone char by 79 and 31 %, respectively. Regeneration of the F-loaded bone char using 0.5 M NaOH solution leads to a sorption capacity for fluoride of 3.1 mg/g in the second loading cycle. Fluoride breakthrough curve obtained in a fixed-bed column presents an asymmetrical S-shaped form, with a slow approach of C/C 0  → 1.0 due to pore diffusion phenomena. Considering the guideline value for drinking water of 1.5 mg F - /L, as recommended by World Health Organization, the service cycle for fluoride removal was of 71.0 h ([F - ] feed  ∼ 9 mg/L; flow rate = 1 mL/min; m sorbent  = 12.6 g). A mass transfer model considering the pore diffusion was able to satisfactorily describe the experimental data obtained in batch and continuous systems.

Charring does not affect wood infestation by subterranean termites

Science.gov (United States)

C.J. Peterson; P.D. Gerard; T.L. Wagner

2007-01-01

Fire is an important part of forest ecosystems, as is the insect fauna. Changes in wood brought aboutby fire may alter the ability of termites to use the wood, interrupting the decay cycle of woody debris.The ability of termites to find, infest, and feed upon wood after it had been charred was evaluated in

Structural characteristics and gasification reactivity of chars prepared from K{sub 2}CO{sub 3} mixed HyperCoals and coals

Energy Technology Data Exchange (ETDEWEB)

Atul Sharma; Hiroyuki Kawashima; Ikuo Saito; Toshimasa Takanohashi [National Institute of Advanced Industrial Science and Technology, Ibaraki (Japan). Advanced Fuel Group

2009-04-15

HyperCoal is a clean coal with mineral matter content <0.05 wt %. Oaky Creek (C = 82%), and Pasir (C = 68%) coals were subjected to solvent extraction method to prepare Oaky Creek HyperCoal, and Pasir HyperCoal. Experiments were carried out to compare the gasification reactivity of HyperCoals and parent raw coals with 20, 40, 50 and 60% K{sub 2}CO{sub 3} as a catalyst at 600, 650, 700, and 775{sup o}C with steam. Gasification rates of coals and HyperCoals were strongly influenced by the temperature and catalyst loading. Catalytic steam gasification of HyperCoal chars was found to be chemical reaction controlled in the 600-700{sup o}C temperature range for all catalyst loadings. Gasification rates of HyperCoal chars were found to be always higher than parent coals at any given temperature for all catalyst loadings. However, X-ray diffraction results showed that the microstructures of chars prepared from coals and HyperCoals were similar. Results from nuclear magnetic resonance spectroscopy show no significant difference between the chemical compositions of the chars. Significant differences were observed from scanning electron microscopy images, which showed that the chars from HyperCoals had coral-reef like structures whereas dense chars were observed for coals. 26 refs., 8 figs., 2 tabs.

Textural properties of chars as determined by petrographic analysis: comparison between air-blown, oxygen-blown and oxygen-enriched gasification

CSIR Research Space (South Africa)

Oboirien, BO

2012-11-01

Full Text Available In this study, the textural properties of chars generated from a vitrinite, high ash coal in a fluidised bed gasifier under air-blown, oxygen-blown and oxygen-enriched conditions were determined by detailed petrographic analysis. The char samples...

Chemical, structural and combustion characteristics of carbonaceous products obtained by hydrothermal carbonization of palm empty fruit bunches.

Science.gov (United States)

Parshetti, Ganesh K; Kent Hoekman, S; Balasubramanian, Rajasekhar

2013-05-01

A carbon-rich solid product, denoted as hydrochar, was synthesized by hydrothermal carbonization (HTC) of palm oil empty fruit bunch (EFB), at different pre-treatment temperatures of 150, 250 and 350 °C. The conversion of the raw biomass to its hydrochar occurred via dehydration and decarboxylation processes. The hydrochar produced at 350 °C had the maximum energy-density (>27 MJ kg(-1)) with 68.52% of raw EFB energy retained in the char. To gain a detailed insight into the chemical and structural properties, carbonaceous hydrochar materials were characterized by FE-SEM, FT-IR, XRD and Brunauer-Emmett-Teller (BET) analyses. This work also investigated the influence of hydrothermally treated hydrochars on the co-combustion characteristics of low rank Indonesian coal. Conventional thermal gravimetric analysis (TGA) parameters, kinetics and activation energy of different hydrochar and coal blends were estimated. Our results show that solid hydrochars improve the combustion of low rank coals for energy generation. Copyright © 2012 Elsevier Ltd. All rights reserved.

AUS burnup module CHAR and the associated data pool

International Nuclear Information System (INIS)

Robinson, G.S.

1975-12-01

The CHAR module of the AUS reactor neutronics scheme solves the multiregion nuclide depletion equations using an analytic method. The module obtains cross section, flux and geometry data from AUS data pools, and uses the STATUS data pool which has been designed for the storage of nuclide compositions, spatial smearing factors and other miscellaneous information. (author)

Aerosols from biomass combustion

Energy Technology Data Exchange (ETDEWEB)

Nussbaumer, T

2001-07-01

This report is the proceedings of a seminar on biomass combustion and aerosol production organised jointly by the International Energy Agency's (IEA) Task 32 on bio energy and the Swiss Federal Office of Energy (SFOE). This collection of 16 papers discusses the production of aerosols and fine particles by the burning of biomass and their effects. Expert knowledge on the environmental impact of aerosols, formation mechanisms, measurement technologies, methods of analysis and measures to be taken to reduce such emissions is presented. The seminar, visited by 50 participants from 11 countries, shows, according to the authors, that the reduction of aerosol emissions resulting from biomass combustion will remain a challenge for the future.

Aerosols from biomass combustion

Energy Technology Data Exchange (ETDEWEB)

Nussbaumer, T.

2001-07-01

This report is the proceedings of a seminar on biomass combustion and aerosol production organised jointly by the International Energy Agency's (IEA) Task 32 on bio energy and the Swiss Federal Office of Energy (SFOE). This collection of 16 papers discusses the production of aerosols and fine particles by the burning of biomass and their effects. Expert knowledge on the environmental impact of aerosols, formation mechanisms, measurement technologies, methods of analysis and measures to be taken to reduce such emissions is presented. The seminar, visited by 50 participants from 11 countries, shows, according to the authors, that the reduction of aerosol emissions resulting from biomass combustion will remain a challenge for the future.

The hierarchical porous structure bio-char assessments produced by co-pyrolysis of municipal sewage sludge and hazelnut shell and Cu(II) adsorption kinetics.

Science.gov (United States)

Zhao, Bing; Xu, Xinyang; Zeng, Fanqiang; Li, Haibo; Chen, Xi

2018-05-04

The co-pyrolysis technology was applied to municipal sewage sludge (MSS) and hazelnut shell with alkaline activating agent K 2 CO 3 under N 2 atmosphere. The innovative bio-char produced by co-pyrolysis had significant physical and chemical characteristics. The specific surface area reached 1990.23 m 2 /g, and the iodine absorption number was 1068.22 mg/g after co-pyrolysis at 850 °C. Although hazelnut shell was a kind of solid waste, it also had abundant cellulose resource, which could contribute to porous structure of bio-char during co-pyrolysis with MSS and decrease total heavy metals contents of raw material to increase security of bio-chars. Meanwhile, the residual fractions of heavy metals in bio-char were above 92.95% after co-pyrolysis at 900 °C except Cd to prevent heavy metals digestion, and the bio-char presented significant immobilization behavior from co-pyrolysis technology. Moreover, the yield and the iodine absorption number of bio-chars under different process variables were analyzed, and it was confirmed that appropriate process variables could contribute the yield and the iodine absorption number of bio-char and prevent to etch pore structure excessively to collapse. The changes of surface functional groups and crystallographic structure before and after co-pyrolysis were analyzed by FTIR and XRD, respectively. The hierarchical porous structure of bio-char was presented by SEM and N 2 adsorption-desorption isotherm. The Cu(II) adsorption capacity of the bio-char was 42.28 mg/g after 24 h, and surface functional groups acted as active binding sites for Cu(II) adsorption. Langmuir model and pseudo-second-order model can describe process of Cu(II) adsorption well.

El Duque de San Pedro de Galatino y la azucarera de Láchar

OpenAIRE

Francisco José Sánchez Sánchez

2015-01-01

El objetivo del trabajo ha sido el estudio de la fábrica azucarera, construida en el año 1890 en la localidad de Láchar (Granada), denominada “Fábrica Conde de Benalúa”, propiedad de Julio Quesada Cañaveral y Piédrola, Señor de Láchar, Conde de Benalúa y de lasVillas, Duque de San Pedro de Galatino y Grande de España. La metodología ha sido posible gracias a la búsqueda de la documentación en los archivos públicos, nacionales, provinciales, locales y privados. Las conclusiones que presentamos...

Thermogravimetric determination of the carbon dioxide reactivity of char from some New Zealand coals and its association with the inorganic geochemistry of the parent coal

Energy Technology Data Exchange (ETDEWEB)

Beamish, B.B.; Shaw, K.J.; Rodgers, K.A.; Newman, J. [University of Auckland, Auckland (New Zealand). Dept. of Geology

1998-02-01

Thermogravimetrically-determined carbon dioxide reactivities of char formed from New Zealand coals, ranging in rank from lignite to high volatile bituminous, vary from 0.12 to 10.63 mg/h/mg on a dry, ash-free basis. The lowest rank subbituminous coal chars have similar reactivities to the lignite coal chars. Calcium content of the char shows the strongest correlation with reactivity, which increases as the calcium content increases. High calcium per se does not directly imply a high char reactivity. Organically-bound calcium catalyses the conversion of carbon to carbon monoxide in the presence of carbon dioxide, whereas calcium present as discrete minerals in the coal matrix e.g., calcite, fails to significantly affect reactivity. Catalytic effects of magnesium, iron, sodium and phosphorous are not as obvious, but can be recognised for individual chars. The thermogravimetric technique provides a fast, reliable analysis that is able to distinguish char reactivity differences between coals, which may be due to any of the above effects. 27 refs., 6 figs., 4 tabs.

Bio-oil and bio-char production from corn cobs and stover by fast pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Mullen, Charles A.; Boateng, Akwasi A.; Goldberg, Neil M.; Hicks, Kevin B. [Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 E. Mermaid Lane, Wyndmoor, PA 19038 (United States); Lima, Isabel M. [Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 1100 Robert E. Lee Blvd., New Orleans, LA 70124 (United States); Laird, David A. [National Soil Tilth Laboratory, U.S. Agricultural Research Service, U.S. Department of Agriculture, 2110 University Blvd., Ames, IA 50011 (United States)

2010-01-15

Bio-oil and bio-char were produced from corn cobs and corn stover (stalks, leaves and husks) by fast pyrolysis using a pilot scale fluidized bed reactor. Yields of 60% (mass/mass) bio-oil (high heating values are {proportional_to}20 MJ kg{sup -1}, and densities >1.0 Mg m{sup -3}) were realized from both corn cobs and from corn stover. The high energy density of bio-oil, {proportional_to}20-32 times on a per unit volume basis over the raw corn residues, offers potentially significant savings in transportation costs particularly for a distributed ''farm scale'' bio-refinery system. Bio-char yield was 18.9% and 17.0% (mass/mass) from corn cobs and corn stover, respectively. Deploying the bio-char co-product, which contains most of the nutrient minerals from the corn residues, as well as a significant amount of carbon, to the land can enhance soil quality, sequester carbon, and alleviate environmental problems associated with removal of crop residues from fields. (author)

RESULTS OF THE DIESEL COMBUSTION CHAMBER OPTIMIZED DESIGN IN THE MULTICRITERIAL TASK ENVIRONMENT

Directory of Open Access Journals (Sweden)

A. Wrublewski

2015-12-01

Full Text Available The results of optimized designing of the higi-speed vehicle diesel engine combustion chamber based on application of the method of parameters space investingation are given. The optimal form of the combustion chamber and the direction of fuel jets at adjusted pressure rate and other functional resrictions are determined according to three criteria of quality – fuel consumption, hard particles and nitric oxide emissions.

Current status, between-year comparisons and maternal transfer of organohalogenated compounds (OHCs) in Arctic char (Salvelinus alpinus) from Bjørnøya, Svalbard (Norway)

International Nuclear Information System (INIS)

Bytingsvik, J.; Frantzen, M.; Götsch, A.; Heimstad, E.S.; Christensen, G.; Evenset, A.

2015-01-01

High levels of organohalogenated compounds (OHCs) have been found in Arctic char from Lake Ellasjøen at Bjørnøya (Svalbard, Norway) compared to char from other arctic lakes. The first aim of the study was to investigate the OHC status, contaminant profile, and partitioning of OHCs between muscle and ovary tissue in spawning female char from the high-polluted Lake Ellasjøen and the low-polluted Lake Laksvatn. The second aim was to investigate if OHC levels in muscle tissue have changed over time. Between-lake comparisons show that the muscle levels (lipid weight) of hexachlorobenzene (HCB), chlordanes (∑ CHLs), mirex, dichlorodiphenyltrichloroethanes (∑ DDTs) and polychlorinated biphenyls (∑ PCBs) were up to 36 times higher in char from Ellasjøen than in Laksvatn, and confirm that the char from Ellasjøen are still heavily exposed compared to char from neighboring lake. A higher proportion of persistent OHCs were found in Ellasjøen compared to Laksvatn, while the proportion of the less persistent OHCs was highest in Laksvatn. A between-year comparison of OHC levels (i.e., HCB, DDTs, PCBs) in female and male char shows higher levels of HCB in female char from Ellasjøen in 2009/2012 compared to in 1999/2001. No other between-year differences in OHC levels were found. Due to small study groups, findings associated with between-year differences in OHC levels should be interpreted with caution. OHCs accumulate in the lipid rich ovaries of spawning females, resulting in up to six times higher levels of OHCs in ovaries compared to in muscle (wet weight). The toxic equivalent (TEQ)-value for the dioxin-like PCBs (PCB-105 and -118) in ovaries of the Ellasjøen char exceeded levels associated with increased egg mortality in rainbow trout (Oncorhynchus mykiss). Hence, we suggest that future studies should focus on the reproductive health and performance abilities of the high-exposed population of char inhabiting Lake Ellasjøen. - Highlights: • Examine levels

Current status, between-year comparisons and maternal transfer of organohalogenated compounds (OHCs) in Arctic char (Salvelinus alpinus) from Bjørnøya, Svalbard (Norway)

Energy Technology Data Exchange (ETDEWEB)

Bytingsvik, J., E-mail: jenny.bytingsvik@akvaplan.niva.no [Akvaplan-niva AS, The Fram Centre, N-9296 Tromsø Norway (Norway); Frantzen, M. [Akvaplan-niva AS, The Fram Centre, N-9296 Tromsø Norway (Norway); Götsch, A.; Heimstad, E.S. [NILU (Norwegian Institute for Air Research), The Fram Centre, N-9296 Tromsø Norway (Norway); Christensen, G. [Akvaplan-niva AS, The Fram Centre, N-9296 Tromsø Norway (Norway); Evenset, A. [Akvaplan-niva AS, The Fram Centre, N-9296 Tromsø Norway (Norway); University of Tromsø, The Arctic University of Norway, Pb 6050 Langnes, N-9037 Tromsø (Norway)

2015-07-15

High levels of organohalogenated compounds (OHCs) have been found in Arctic char from Lake Ellasjøen at Bjørnøya (Svalbard, Norway) compared to char from other arctic lakes. The first aim of the study was to investigate the OHC status, contaminant profile, and partitioning of OHCs between muscle and ovary tissue in spawning female char from the high-polluted Lake Ellasjøen and the low-polluted Lake Laksvatn. The second aim was to investigate if OHC levels in muscle tissue have changed over time. Between-lake comparisons show that the muscle levels (lipid weight) of hexachlorobenzene (HCB), chlordanes (∑ CHLs), mirex, dichlorodiphenyltrichloroethanes (∑ DDTs) and polychlorinated biphenyls (∑ PCBs) were up to 36 times higher in char from Ellasjøen than in Laksvatn, and confirm that the char from Ellasjøen are still heavily exposed compared to char from neighboring lake. A higher proportion of persistent OHCs were found in Ellasjøen compared to Laksvatn, while the proportion of the less persistent OHCs was highest in Laksvatn. A between-year comparison of OHC levels (i.e., HCB, DDTs, PCBs) in female and male char shows higher levels of HCB in female char from Ellasjøen in 2009/2012 compared to in 1999/2001. No other between-year differences in OHC levels were found. Due to small study groups, findings associated with between-year differences in OHC levels should be interpreted with caution. OHCs accumulate in the lipid rich ovaries of spawning females, resulting in up to six times higher levels of OHCs in ovaries compared to in muscle (wet weight). The toxic equivalent (TEQ)-value for the dioxin-like PCBs (PCB-105 and -118) in ovaries of the Ellasjøen char exceeded levels associated with increased egg mortality in rainbow trout (Oncorhynchus mykiss). Hence, we suggest that future studies should focus on the reproductive health and performance abilities of the high-exposed population of char inhabiting Lake Ellasjøen. - Highlights: • Examine levels

Hydrothermal carbonization and torrefaction of grape pomace: a comparative evaluation.

Science.gov (United States)

Pala, Mehmet; Kantarli, Ismail Cem; Buyukisik, Hasan Baha; Yanik, Jale

2014-06-01

Grape pomace was treated by hydrothermal carbonization (sub-critical water, 175-275°C) and torrefaction (nitrogen atmosphere, 250 and 300°C), with mass yield of solid product (char) ranging between 47% and 78%, and energy densification ratio to 1.42-1.15 of the original feedstock. The chars were characterised with respect to their fuel properties, morphological and structural properties and combustion characteristics. The hydrothermal carbonization produced the char with greater energy density than torrefaction. The chars from torrefaction were found to be more aromatic in nature than that from hydrothermal carbonization. Hydrothermal carbonization process produced the char having high combustion reactivity. Most interesting was the finding that aqueous phase from hydrothermal carbonization had antioxidant activity. The results obtained in this study showed that HTC appears to be promising process for a winery waste having high moisture content. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adsorption of copper onto char derived macro alga, Undaria pinnatifida

International Nuclear Information System (INIS)

Cho, Hye Jung; Ko, Jeong Huy; Heo, Hyeon Su; Park, Hye Jin; BAe, Yoon Ju; Kim, Jung Hwan; Park, Young-Kwon

2010-01-01

Full text: A release of heavy metals into the environment by industrial activities raises much environmental problems because they tend to remain indefinitely, circulating and eventually accumulating throughout the food chain. Copper is essential to human life and health but, like all heavy metals, is potentially toxic as well. The excessive intakes of copper result in its accumulation in the liver and produce gastrointestinal problems, kidney damage, anemia, and continued inhalation of copper-containing sprays is linked with an increase in lung cancer among exposed people. Consequently, we need to eliminate the copper in drinking water. Also, growth rates of marine macro algae far exceed those of terrestrial biomass, without water limitations, so annual primary production rates are higher for the major marine macro algae than for most terrestrial biomass. According to these reasons, we try to use the macro alga, Undaria pinnatifida. Adsorption of heavy metals is one of the possible technologies involved in the removal of toxic metals from industrial waste streams and mining waste water using low-cost adsorbents. In recent years, many low-cost adsorbents such as seaweeds, activated carbon, etc. have been investigated, but the char by macro alga, Undaria pinnatifida, have not proven to be the most effective and promising substrates. The aim of this study is to remove copper from its aqueous solution by Undaria pinnatifida char for various parameters like pH, contact time, and Cu(II) concentration. The adsorption capacity of Cu(II) by Undaria pinnatifida char was investigated as a function of pH, contact time, and Cu(II) concentration at room temperature. And it was verified using equilibrium studies. (author)

Adsorption of Escherichia coli Using Bone Char | Rezaee | Journal ...

African Journals Online (AJOL)

The aim of study was providing a novel adsorbent for the removal of Escherichia coli (E.coli) as a microbial model from contaminated air especially in hospital units using bone char (BC). The BC was prepared from cattle animal bone by pyrolysis in a furnace at 450°C for 2 h. The characteristics of BC have been determined ...

Increased combustion stability in modulating biomass boilers for district heating systems

Energy Technology Data Exchange (ETDEWEB)

Eriksson, Gunnar; Hermansson, Roger (eds.) [Lulea Univ. of Technology (Sweden)

2002-09-01

One of the problems in small district heating systems is the large load variation that must be handled by the system. If the boiler is designed to cover the needs during the coldest day in winter time in northern Europe it would have to run at loads as low as 10% of full load during summer time, when heat is needed only for tap water production. Load variations in small networks are quite fast and earlier investigations have shown that existing biomass boilers give rise to large amounts of harmful emissions at fast load variations and at low loads. The problem has been addressed in different ways: Three new boiler concepts have been realized and tested: A prototype of a 500 kW boiler with partitioned primary combustion chamber and supplied with a water heat store. A 10 kW bench scale combustor and a 500 kW prototype boiler based on pulsating combustion. Bench scale boilers to test the influence from applied sound on emissions and a 150 kW prototype boiler with a two-stage secondary vortex combustion chamber. Development of control and regulating equipment: Glow Guard, a control system using infra-red sensors to detect glowing char on the grate, has been constructed and tested. A fast prediction model that can be used in control systems has been developed. Simulation of the combustion process: Code to simulate pyrolysis/gasification of fuel on the grate has been developed. Combustion of the gas phase inside the combustion chamber has been simulated. The two models have been combined to describe the combustion process inside the primary chamber of a prototype boiler. A fast simulation code based on statistical methods that can predict the environmental performance of boilers has been developed. One of the boiler concepts matches the desired load span from 10 to 100% of full load with emissions far below the set limits for CO and THC and close to the set limits for NO{sub x}. The other boilers had a bit more narrow load range, one with very low emissions except for NO

In vitro adsorption of sodium pentobarbital by SuperChar, USP and Darco G-60 activated charcoals

International Nuclear Information System (INIS)

Curd-Sneed, C.D.; Parks, K.S.; Bordelon, J.G.; Stewart, J.J.

1987-01-01

This study was designed to examine the in vitro adsorption of sodium pentobarbital by three activated charcoals. Solutions of sodium pentobarbital (20 mM) were prepared in distilled water and in 70% sorbitol (w/v). Radiolabeled ( 14 C) sodium pentobarbital was added to each solution to serve as a concentration marker. Two ml of each drug solution was added to test tubes containing 40 mg of either Darco G-60, USP, or SuperChar activated charcoal. The drug-charcoal mixtures were incubated at 37 degrees C for O, 2.5, 5, 7.5 or 10 min. Equilibrium, indicated by a constant percentage of drug bound for two consecutive time periods, was established immediately for the aqueous mixtures and for Darco G-60 in sorbitol. The time to equilibrium was prolonged for USP (2.5 min) and SuperChar (5 min) in the presence of sorbitol. In the second series of experiments, solutions of sodium pentobarbital (1.25 to 160 mM) were prepared in either distilled water or sorbitol. Amount of drug bound by 10 to 320 mg of activated charcoal within a 10 min incubation period was determined. Scatchard analysis determined maximum binding capacity (Bmax) and dissociation constants (Kd) for each activated charcoal. In water, Bmax (mumoles/gm) was greatest for SuperChar (1141), followed by USP (580) and Darco G-60 (381), while the Kd's did not differ. Sorbitol did not change the Bmax or Kd of USP or Darco G-60, but the additive significantly decreased the Bmax (717) and increased the Kd for SuperChar (3.3 to 10.1 mM). The results suggest that relative binding capacity of activated charcoal is directly proportional to surface area, and that sorbitol significantly reduces sodium pentobarbital binding to SuperChar

Desulfurization of coal by pyrolysis and hydropyrolysis with addition of KOH/NaOH

Energy Technology Data Exchange (ETDEWEB)

Quanrun Liu; Haoquan Hu; Shengwei Zhu; Qiang Zhou; Wenying Li; Xianyong Wei; Kechang Xie [Dalian University of Technology, Dalian (China). Institute of Coal Chemical Engineering

2005-08-01

In this paper, a two-step desulfurization process for high-sulfur coal was investigated. Two Chinese coals with the addition of 10 wt % potassium hydroxide or sodium hydroxide were pyrolyzed under an atmosphere of nitrogen or hydrogen in a fixed-bed reactor at 600{sup o}C, and then the obtained chars were washed with hot water. The results indicated that, without the addition of an alkali component, the sulfur removal of these two coals by pyrolysis and hydropyrolysis is {approximately}40%-50% and the sulfur content of chars is reduced only slightly, in comparison with the original coals; with the addition of 10 wt % potassium hydroxide or sodium hydroxide into the original coals and the chars being washed with hot water, the sulfur removal is {approximately}70%-80% and the sulfur content in chars is reduced dramatically. The combustion behavior of chars was also investigated, using thermogravimetric analysis. The results showed that those chars that had an added alkali component and were subjected to water-washing were more reactive and can be burned more easily than those without added alkali, which was also confirmed by a kinetics analysis of char combustion. 21 refs., 3 figs., 6 tabs.

CharToon 2.1 extensions : expression repertoire and lip sync

NARCIS (Netherlands)

Z.M. Ruttkay; A.D.F. Lelièvre (Alban)

2000-01-01

textabstractCharToon is a modular system to design and animate 21/2D faces and other graphic al objects. This report contains the extensions made for version 2.1, effecting only the Animation Editor module. The new features allow the re-usage of a reper toire of expression snapshots and animations

Characterization of red mud-epoxy intumescent char using surface imaging and micro analysis

Energy Technology Data Exchange (ETDEWEB)

Arogundade, A. I., E-mail: ajiunolorioba@gmail.com; Megat-Yusoff, P. S. M., E-mail: puteris@petronas.com.my; Faiz, A. [Department of Mechanical Engineering, Universiti Tecknologi Petronas (Malaysia); Bhat, A. H. [Department of Fundamental and Applied Science, Universiti Tecknologi Petronas (Malaysia)

2015-07-22

In this study, red mud (RM), an oxide waste was proposed as reinforcing, synergistic filler for the traditional epoxy intumescent coating (IC). 5.5 wt% of acid-modified and unmodified red mud were introduced into the basic intumescent formulation of ammonium polyphosphate (APP), pentaerythritol (PER) and melamine (MEL). In order to predict effect of modification on its suitability, Field emission electron scanning microscopy and Fourier transform infra red were used to obtain detailed characteristics such as the cell size, pore distribution, homogeneity and chemical composition of the red mud-epoxy carbonaceous char. Both acid-modified and unmodified RM-filled ICs produced chars with smaller and more closely packed cells compared to chars from the unfilled coating. Both coating types had hard carbonaceous metal phosphate coverings that could act as heat barriers. The unmodified red mud was found to be antagonistic to the intumescent action with an expansion of only 2 times the initial thickness. The leached, low iron-red mud produced an expansion of 15 times the initial thickness, but possessed a hollow interior. From these findings, it may be deduced that while acid leaching of red mud may improve intumescent expansion, it would be necessary to optimize the percent filler loading to improve residual mass.

Pyrolysis of waste animal fats in a fixed-bed reactor: Production and characterization of bio-oil and bio-char

Energy Technology Data Exchange (ETDEWEB)

Ben Hassen-Trabelsi, A., E-mail: aidabenhassen@yahoo.fr [Centre de Recherche et de Technologies de l’Energie (CRTEn), Technopôle Borj-Cédria, B.P 95, 2050, Hammam Lif (Tunisia); Kraiem, T. [Centre de Recherche et de Technologies de l’Energie (CRTEn), Technopôle Borj-Cédria, B.P 95, 2050, Hammam Lif (Tunisia); Département de Géologie, Université de Tunis, 2092, Tunis (Tunisia); Naoui, S. [Centre de Recherche et de Technologies de l’Energie (CRTEn), Technopôle Borj-Cédria, B.P 95, 2050, Hammam Lif (Tunisia); Belayouni, H. [Département de Géologie, Université de Tunis, 2092, Tunis (Tunisia)

2014-01-15

Highlights: • Produced bio-fuels (bio-oil and bio-char) from some animal fatty wastes. • Investigated the effects of main parameters on pyrolysis products distribution. • Determined the suitable conditions for the production of the maximum of bio-oil. • Characterized bio-oils and bio-chars obtained from several animal fatty wastes. - Abstract: Several animal (lamb, poultry and swine) fatty wastes were pyrolyzed under nitrogen, in a laboratory scale fixed-bed reactor and the main products (liquid bio-oil, solid bio-char and syngas) were obtained. The purpose of this study is to produce and characterize bio-oil and bio-char obtained from pyrolysis of animal fatty wastes. The maximum production of bio-oil was achieved at a pyrolysis temperature of 500 °C and a heating rate of 5 °C/min. The chemical (GC–MS analyses) and spectroscopic analyses (FTIR analyses) of bio-oil showed that it is a complex mixture consisting of different classes of organic compounds, i.e., hydrocarbons (alkanes, alkenes, cyclic compounds…etc.), carboxylic acids, aldehydes, ketones, esters,…etc. According to fuel properties, produced bio-oils showed good properties, suitable for its use as an engine fuel or as a potential source for synthetic fuels and chemical feedstock. Obtained bio-chars had low carbon content and high ash content which make them unattractive for as renewable source energy.

Pyrolysis of waste animal fats in a fixed-bed reactor: Production and characterization of bio-oil and bio-char

International Nuclear Information System (INIS)

Ben Hassen-Trabelsi, A.; Kraiem, T.; Naoui, S.; Belayouni, H.

2014-01-01

Highlights: • Produced bio-fuels (bio-oil and bio-char) from some animal fatty wastes. • Investigated the effects of main parameters on pyrolysis products distribution. • Determined the suitable conditions for the production of the maximum of bio-oil. • Characterized bio-oils and bio-chars obtained from several animal fatty wastes. - Abstract: Several animal (lamb, poultry and swine) fatty wastes were pyrolyzed under nitrogen, in a laboratory scale fixed-bed reactor and the main products (liquid bio-oil, solid bio-char and syngas) were obtained. The purpose of this study is to produce and characterize bio-oil and bio-char obtained from pyrolysis of animal fatty wastes. The maximum production of bio-oil was achieved at a pyrolysis temperature of 500 °C and a heating rate of 5 °C/min. The chemical (GC–MS analyses) and spectroscopic analyses (FTIR analyses) of bio-oil showed that it is a complex mixture consisting of different classes of organic compounds, i.e., hydrocarbons (alkanes, alkenes, cyclic compounds…etc.), carboxylic acids, aldehydes, ketones, esters,…etc. According to fuel properties, produced bio-oils showed good properties, suitable for its use as an engine fuel or as a potential source for synthetic fuels and chemical feedstock. Obtained bio-chars had low carbon content and high ash content which make them unattractive for as renewable source energy

Coal devolatilization and char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

DEFF Research Database (Denmark)

Jensen, Anker Degn; Brix, Jacob; Jensen, Peter Arendt

2010-01-01

have been carried out in an electrically heated entrained flow reactor that is designed to simulate the conditions in a suspension fired boiler. Coal devolatilized in N2 and CO2 atmospheres provided similar results regarding char morphology, char N2-BET surface area and volatile yield. This strongly......The aim of the present investigation is to examine differences between O2/N2 and O2/CO2 atmospheres during devolatilization and char conversion of a bituminous coal at conditions covering temperatures between 1173 K and 1673 K and inlet oxygen concentrations between 5 and 28 vol.%. The experiments...

Apparatus and method for solid fuel chemical looping combustion

Science.gov (United States)

Siriwardane, Ranjani V; Weber, Justin M

2015-04-14

The disclosure provides an apparatus and method utilizing fuel reactor comprised of a fuel section, an oxygen carrier section, and a porous divider separating the fuel section and the oxygen carrier section. The porous divider allows fluid communication between the fuel section and the oxygen carrier section while preventing the migration of solids of a particular size. Maintaining particle segregation between the oxygen carrier section and the fuel section during solid fuel gasification and combustion processes allows gases generated in either section to participate in necessary reactions while greatly mitigating issues associated with mixture of the oxygen carrier with char or ash products. The apparatus and method may be utilized with an oxygen uncoupling oxygen carrier such as CuO, Mn.sub.3O.sub.4, or Co.sub.3O.sub.4, or utilized with a CO/H.sub.2 reducing oxygen carrier such as Fe.sub.2O.sub.3.

Cesium in Arctic char lakes - effects of the Chernobyl accident

International Nuclear Information System (INIS)

Hammar, J.; Notter, M.; Neumann, G.

1991-01-01

Fallout radiocesium from the Chernobyl accident caused extensive contamination in a region of previously well studied alpine lake ecosystems in northern Sweden. Levels of Cs-137 in the barren catchment basins reached 20-50 kBq/m 2 during 1986. The distribution, pathways and major transport mechanisms of radiocesium through the lake ecosystems were studied during 1986-1990. Levels of Cs-137, Cs-134 and K-40 in water, surface sediment, detritus (sediment traps) and different trophic levels of the food chains of Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) were monitored in a series of lakes forming a matrix of 4 natural lakes and 3 lake reservoirs, with or without the introduced new fish food organism, Mysis relicta. The reservoirs were found to act as sinks for radiocesium with extensive accumulation recorded in water, detritus, sediment, invertebrates and salmonids. Whereas concentrations in water and biota have declined from the extreme peak levels in 1986-1987, the levels in surface sediment increased extensively until fall of 1988. The concentration of Cs-137 in fish populations feeding on benthic invertebrates, i.e. mysids and amphipods, were significantly higher than in planktivorous fish. During the three first winters a significant increase in levels of Cs-137 in winter active Arctic char were recorded, whereas the levels declined during the succeeding summers. The introduced Mysis relicta were found to enhance the transport of Cs-137 from zooplankton and settling particles to Arctic char and brown trout. The results suggest a successive change in transport of radiocesium from water via zooplankton to planktivorous fish during the early summer of 1986 to post-depositional mobilization via benthic organisms to benthic fish in successive years. (213 refs.) (au)

CFD modeling of combustion processes using KIVA3V Code with partially stirred reactor model for turbulence-combustion interactions

International Nuclear Information System (INIS)

Jarnicki, R.; Sobiesiak, A.

2002-01-01

In order to solve the averaged conservation equations for turbulent reacting flow one is faced with a task of specifying the averaged chemical reaction rate. This is due to turbulence influence on the mean reaction rates that appear in the species concentration Reynolds-averaged equation. In order to investigate the Partially Stirred Reactor (PaSR) combustion model capabilities, a CFD modeling using KIVA3V Code with the PaSR model of two very different combustion processes, was performed. Experimental results were compared with modeling

Surface characterisation of synthetic coal chars made from model compounds

Energy Technology Data Exchange (ETDEWEB)

Arenillas, A.; Pevida, C.; Rubiera, F.; Palacios, J.M.; Navarrete, R.; Denoyel, R.; Rouquerol, J.; Pis, J.J. [Instituto Nacional del Carbon, CSIC, Oviedo (Spain)

2004-07-01

Knowledge of surface properties is essential for understanding the reaction mechanisms involved in several coal conversion processes. However, due to the complexity and heterogeneity of coal this is rather difficult and the use of known model compounds could be a valuable tool. Single model compounds have been widely used, but they give a quite simplified picture. In this work a mixture of model compounds in a phenol-formaldehyde matrix was cured in order to create cross-linked structures. The obtained synthetic coal was pyrolysed in a fixed bed reactor, under helium atmosphere. The surface composition of the chars was evaluated by XPS, adsorption gravimetry of water vapour, temperature-programmed desorption and potentiometric titration. Texture was characterised by N{sub 2} and CO{sub 2} adsorption isotherms at 77 and 273 K, respectively, and immersion calorimetry in benzene. The results obtained from the different techniques were contrasted in order to give an overview of the surface properties (chemical and physical) of the samples studied. Chars obtained under the same operating conditions from a high volatile bituminous coal were used as a reference.

ADSORPTION OF MANGANESE FROM ACID MINE DRAINAGE EFFLUENTS USING BONE CHAR: CONTINUOUS FIXED BED COLUMN AND BATCH DESORPTION STUDIES

Directory of Open Access Journals (Sweden)

D. C. Sicupira

2015-06-01

Full Text Available AbstractIn the present study, continuous fixed bed column runs were carried out in an attempt to evaluate the feasibility of using bone char for the removal of manganese from acid mine drainage (AMD. Tests using a laboratory solution of pure manganese at typical concentration levels were also performed for comparison purposes. The following operating variables were evaluated: column height, flow rate, and initial pH. Significant variations in resistance to the mass transfer of manganese into the bone char were identified using the Thomas model. A significant effect of the bed height could only be observed in tests using the laboratory solution. No significant change in the breakthrough volume could be observed with different flow rates. By increasing the initial pH from 2.96 to 5.50, the breakthrough volume was also increased. The maximum manganese loading capacity in continuous tests using bone char for AMD effluents was 6.03 mg g-1, as compared to 26.74 mg g-1 when using the laboratory solution. The present study also performed desorption tests, using solutions of HCl, H2SO4, and water, aimed at the reuse of the adsorbent; however, no promising results were obtained due to low desorption levels associated with a relatively high mass loss. Despite the desorption results, the removal of manganese from AMD effluents using bone char as an adsorbent is technically feasible and attends to environmental legislation. It is interesting to note that the use of bone char for manganese removal may avoid the need for pH corrections of effluents after treatment. Moreover, bone char can also serve to remove fluoride ions and other metals, thus representing an interesting alternative material for the treatment of AMD effluents.

Adsorption of heavy metal ions from aqueous solutions by bio-char, a by-product of pyrolysis

International Nuclear Information System (INIS)

Kılıç, Murat; Kırbıyık, Çisem; Çepelioğullar, Özge; Pütün, Ayşe E.

2013-01-01

Bio-char, a by-product of almond shell pyrolysis, was used as an alternative adsorbent precursor for the removal of heavy metal ions from aqueous solutions. The adsorption potential of almond shell bio-char for Ni(II) and Co(II) removal was investigated. Adsorption experiments were carried out by varying pH, adsorbent dosage, initial metal ion concentrations, contact time and temperature to determine the optimum conditions. To describe the equilibrium isotherms the experimental data were analyzed by the Langmuir, Freundlich, Dubinin–Radushkevich (D–R) and Temkin isotherm models. Pseudo-first order, pseudo-second order, and intraparticle diffusion kinetic models were used to find out the kinetic parameters and mechanism of adsorption process. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated for predicting the nature of adsorption. The results showed that bio-char derived from pyrolysis of biomass can be used as a low-cost and effective adsorbent for removal of heavy metal ions from aqueous solutions.

Influence of potassium hydroxide activation on characteristics and environmental risk of heavy metals in chars derived from municipal sewage sludge.

Science.gov (United States)

Li, Zhengjia; Deng, Hui; Yang, Le; Zhang, Genlin; Li, Yuqi; Ren, Yansen

2018-05-01

To investigate the influence of KOH activation on characteristics and environmental risk of heavy metals in chars, sludge was pyrolyzed with varying amount of KOH. The analyzation of characteristics and potential ecological risk evaluation of heavy metals were conducted by surface area analyzer, FTIR, XRD and BCR sequential extraction. The activated chars have higher surface area and lower content of silica compared to those without being activated. The activation of KOH promoted residual fraction of Cd, meanwhile, Zinc, Cr, Ni and Mn were converted to relatively unstable fractions (F2 and F3). The results of risk assessment indicated that the potential ecological risk level of Cd was reduced in activated chars, while risk level of Zn, Cr, Ni and Mn were increased after pyrolysis with KOH activation. The potential ecological risk of heavy metals in activated chars was further declined, and the risk level transformed from moderate to low. Copyright © 2018 Elsevier Ltd. All rights reserved.

Investigation of a process for the pyrolysis of plutonium contaminated combustible solid waste

International Nuclear Information System (INIS)

Longstaff, B.; Cains, P.W.; Elliot, M.N.; Taylor, R.F.

1981-01-01

Pyrolysis offers an attractive first-stage alternative to incineration as a means of weight and volume reduction of solide combustible waste P.C.M, if it is required to recover plutonium from the final product. The avoidance of turbulent conditions associated with incineration should lead to less carry-over of particulates, and the lower operating temperature approximately 700 0 C should be most advantageous to the choice of constructional materials and to plant life. The char product from pyrolysis may be oxidised to a final ash at similarly acceptable low temperatures by passing air over a stirred bed of materials. The recently received draft designs for a cyclone after-burner (plus associated scrubbers and filters etc) offer an attractive method of dispensing of the volatile products of pyrolysis

Determination of reactivity parameters of model carbons, cokes and flame-chars

DEFF Research Database (Denmark)

Sørensen, Lasse Holst; Gjernes, Erik; Jessen, Thomas

1996-01-01

Reactivity profiles are defined and measured with thermogravimetry for a dense metallurgical Longyear coke, a polymer-derived porous active carbon, Carboxen 1000, and three flame-chars, Illinois #6, Pittsburgh #8 and New Mexico Blue #1. For each sample it is found that the reactivity profile can...... and activation energy in oxygen are estimated for each sample over a 100 K temperature range (cases vary from 573 to 885 K) and a maximum oxygen partial pressure range of 0.01-1 bar. For the different fuel samples reaction orders range fromn =0.65 to 0.78, and global activation energies are found in the narrow...... range of 130-133 kJ/mol. For Carboxen n=0.91 and E=146 kJ/mol. The reactivity differences between the coal chars are proposed mainly due to variations in the physical structure. Over the pressure-temperature domain examined reactivity varies considerably, but the structural profile is approximately...

EFFECT OF CALCIUM ADDITION ON THE DEFLUORIDATION CAPACITY OF BONE CHAR

DEFF Research Database (Denmark)

Jacobsen, P.; Dahi, Elian

1997-01-01

Dosage of small amounts of calcium chloride to fluoride water prior to contact with bone char which has already been saturated with fluoride is shown to provide an additional fluoride removal capacity. The additionally obtained removal capacity increases with slower filtration velocities...... to be capable of reducing the fluoride concentration form 10 to about 0.5 mgF/L. The additionally saturated column is shown to be regenerated by simple adjustment of the pH of the water to 11 and allowing to flow for a few bed volumes. The useful regeneration capacity, where the fluoride concentration...... and increasing calcium dosage. A filtration velocity of 0.07 m/h, corresponding to a contact time of about 2 hours, and a dosage of 100 mgCa/L, are shown to provide an additional removal capacity of about 3 mgF/g, i.e. almost a doubling of the genuine removal capacity of the bone char. The process is shown...

Chemical Kinetics in Support of Syngas Turbine Combustion

Energy Technology Data Exchange (ETDEWEB)

Dryer, Frederick

2007-07-31

This document is the final report on an overall program formulated to extend our prior work in developing and validating kinetic models for the CO/hydrogen/oxygen reaction by carefully analyzing the individual and interactive behavior of specific elementary and subsets of elementary reactions at conditions of interest to syngas combustion in gas turbines. A summary of the tasks performed under this work are: 1. Determine experimentally the third body efficiencies in H+O{sub 2}+M = HO{sub 2}+M (R1) for CO{sub 2} and H{sub 2}O. 2. Using published literature data and the results in this program, further develop the present H{sub 2}/O{sub 2}/diluent and CO/H{sub 2}/O{sub 2}/diluent mechanisms for dilution with CO{sub 2}, H{sub 2}O and N{sub 2} through comparisons with new experimental validation targets for H{sub 2}-CO-O{sub 2}-N{sub 2} reaction kinetics in the presence of significant diluent fractions of CO{sub 2} and/or H{sub 2}O, at high pressures. (task amplified to especially address ignition delay issues, see below). 3. Analyze and demonstrate issues related to NOx interactions with syngas combustion chemistry (task amplified to include interactions of iron pentacarbonyl with syngas combustion chemistry, see below). 4. Publish results, including updated syngas kinetic model. Results are summarized in this document and its appendices. Three archival papers which contain a majority of the research results have appeared. Those results not published elsewhere are highlighted here, and will appear as part of future publications. Portions of the work appearing in the above publications were also supported in part by the Department of Energy under Grant No. DE-FG02-86ER-13503. As a result of and during the research under the present contract, we became aware of other reported results that revealed substantial differences between experimental characterizations of ignition delays for syngas mixtures and ignition delay predictions based upon homogenous kinetic modeling. We

A Study on the Applicability of Kinetic Models for Shenfu Coal Char Gasification with CO2 at Elevated Temperatures

Directory of Open Access Journals (Sweden)

Jinsheng Gao

2009-07-01

Full Text Available In this paper, measurements of the CO2 gasification kinetics for two types of Shenfu coal chars, which were respectively prepared by slow and rapid pyrolysis at temperatures of 950 °C and 1,400 °C, were performed by an isothermal thermo-gravimetric analysis under ambient pressure and elevated temperature conditions. Simultaneously, the applicability of the kinetic model for the CO2 gasification reaction of Shenfu coal chars was discussed. The results showed: (i the shrinking un-reacted core model was not appropriate to describe the gasification reaction process of Shenfu coal chars with CO2 in the whole experimental temperature range; (ii at the relatively low temperatures, the modified volumetric model was as good as the random pore model to simulate the CO2 gasification reaction of Shenfu coal chars, while at the elevated temperatures, the modified volumetric model was superior to the random pore model for this process; (iii the integral expression of the modified volumetric model was more favorable than the differential expression of that for fitting the experimental data. Moreover, by simply introducing a function: A = A★exp(ft, it was found that the extensive model of the modified volumetric model could make much better predictions than the modified volumetric model. It was recommended as a convenient empirical model for comprehensive simulation of Shenfu coal char gasification with under conditions close to those of entrained flow gasification.

Fasting augments PCB impact on liver metabolism in anadromous Arctic Char

Science.gov (United States)

Vijayan, M.M.; Aluru, N.; Maule, A.G.; Jorgensen, E.H.

2006-01-01

Anadromous arctic char (Salvelinus alpinus) undertake short feeding migrations to seawater every summer and accumulate lipids, while the rest of the year is spent in fresh water where the accumulated lipid reserves are mobilized. We tested the hypothesis that winter fasting and the associated polychlorinated biphenyls' (PCBs) redistribution from lipid depots to critical tissues impair the liver metabolic capacity in these animals. Char were administered Aroclor 1254 (0, 1, 10, and 100 mg/ kg body mass) orally and maintained for 4 months without feeding to mimic seasonal winter fasting, while fed groups (0 and 100 mg Aroclor 1254/kg) were maintained for comparison. A clear dose-related increase in PCB accumulation and cytochrome P4501A (CYP1A) protein content was observed in the livers of fasted fish. This PCB concentration and CYP1A response with the high dose of Aroclor were 1.5-fold and 3-fold greater in the fasted than in the fed fish, respectively. In fed fish, PCB exposure lowered liver glycogen content, whereas none of the other metabolic indicators were significantly affected. In fasted fish, PCB exposure depressed liver glycogen content and activities of glucose-6-phosphate dehydrogenase, alanine aminotransferase, lactate dehydrogenase, and phosphoenolpyruvate carboxykinase and elevated 3-hydroxyacylcoA dehydrogenase activity and glucocorticoid receptor protein expression. There were no significant impacts of PCB on heat shock protein 70 (hsp70) and hsp90 contents in either fed or fasted fish. Collectively, our study demonstrates that winter emaciation associated with the anadromous lifestyle predisposes arctic char to PCB impact on hepatic metabolism including disruption of the adaptive metabolic responses to extended fasting. ?? 2006 Oxford University Press.

Adsorption of heavy metals by bio-chars produced from pyrolysis of paper mulberry from simulated industrial wastewater

International Nuclear Information System (INIS)

Adil, S.; Asma, M.

2014-01-01

Paper mulberry bio-char (by-product of pyrolysis) was evaluated for the removal of heavy metals (Cd, Cr, Cu, Zn and Pb) from simulated industrial waste water. The surface properties and surface area of the bio-char was found suitable for metal adsorption. Batch sorption studies for adsorption potential of paper mulberry bio-char for Cd, Cr, Cu, Pb and Zn were investigated under different experimental conditions of pH, temperature and contact time. Maximum removal efficiency of Cd, Cu, Pb and Zn was 97.8, 76.8, 85.6, and 82.2 % respectively at pH 12 while maximum removal of Cr was recorded (98%) at pH 2. The removal efficiency showed different behaviour at different contact times. Maximum removal efficiency of Cd, Cr, Zn was 81, 86, 61.4% at contact time of 3 hr. The maximum removal of Cu was 64.2% observed at a contact time of 4 hours while the maximum removal of Pb and Zn was 85% at contact time of 2 hr. The values of the thermodynamic parameters, enthalpy delta H, Gibbs free energy delta G of sorption and entropy delta So were calculated to define endothermic or exothermic behavior of the sorbent used. Negative value of delta G for Cd, Cu, Cr and Pb indicated paper mulberry bio-char as a feasible sorbent for the efficient removal of Cd, Cu, Cr and Pb. Negative value of delta H was observed for Cd and Pb indicating that the adsorption process is exothermic while positive value of delta H was calculated for Cu, Cr and Zn showed that the adsorption is endothermic. The results obtained showed that plant residue bio-char can act as an effective sorbent for the removal of heavy metals from aqueous solutions. (author)

Basic study of charring detection at the laser catheter-tip using back scattering light measurement during therapeutic laser irradiation in blood.

Science.gov (United States)

Takahashi, Mei; Ito, Arisa; Kajihara, Takuro; Matsuo, Hiroki; Arai, Tsunenori

2010-01-01

The purpose of this study is to investigate transient process of the charring at the laser catheter-tip in blood during therapeutic laser irradiation by the back scattering light measurement to detect precursor state of the charring. We took account of using photodynamic therapy for arrhythmia in blood through the laser catheter. We observed the influence of the red laser irradiation (λ=663 nm) upon the shape of red blood cells (RBCs). The RBCs aggregation, round formation, and hemolysis were took place sequentially before charring. With a model blood sandwiched between glass plates simulated as a catheter-tip boundary, we measured diffuse-reflected-light power and transmitted-light power simultaneously and continuously by a microscopic optics during the laser irradiation. We found that measured light power changes were originated with RBCs shape change induced by temperature rise due to the laser irradiation. A gentle peak following a slow descending was observed in the diffuse-reflected-light power history. This history might indicate the precursor state of the charring, in which the hemolysis might be considered to advance rapidly. We think that the measurement of diffuse-reflected-light power history might be able to detect precursor state of charring at the catheter-tip in blood.

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

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.

Corrosive components of nutshells and their chars

OpenAIRE

Karczewski Mateusz; Marczak Marta; Burmistrz Piotr; Makowska Dorota

2016-01-01

Biomass combustion stands among various technologies pointed at fossil fuels consumption decrease. Biomass can be found in very diversified sources spread more evenly across the globe, can be burned with use of traditional combustion solutions and is more CO2 neutral in combustion than their fossil fuel counterparts. On the other hand biomass has several problems with composition that despite its potential diversity. Problem of excess moisture can be already solved by material selection or by...

Carbon conversion predictor for fluidized bed gasification of biomass fuels - from TGA measurements to char gasification particle model

Energy Technology Data Exchange (ETDEWEB)

Konttinen, J.T. [University of Jyvaeskylae, Department of Chemistry, Renewable Energy Programme, POB 35, Jyvaeskylae (Finland); Moilanen, A. [VTT Technical Research Centre of Finland, POB 1000, Espoo (Finland); Martini, N. de; Hupa, M. [Abo Akademi University, Process Chemistry Centre, Combustion and Materials Chemistry, Turku (Finland)

2012-09-15

When a solid fuel particle is injected into a hot fluidized bed, the reactivity of fuel char in gasification reactions (between char carbon and steam and CO{sub 2}) plays a significant role for reaching a good carbon conversion. In this paper, the gasification reactivity data of some solid waste recovered fuels (SRF) obtained from thermogravimetric analysis (TGA) experiments is presented. Gas mixtures (H{sub 2}O, H{sub 2}, CO{sub 2}, CO), were used in the experiments to find the inhibitive effects of CO and H{sub 2}. Average char gasification reactivity values are determined from the TGA results. Kinetic parameters for char carbon gasification reactivity correlations are determined from this data. The Uniform Conversion model is used to account for the change of gasification reaction rate as function of carbon conversion. Some discrepancies, due to complicated ash-carbon interactions, are subjects of further research. In the carbon conversion predictor, laboratory measured reactivity numbers are converted into carbon conversion numbers in a real-scale fluidized bed gasifier. The predictor is a relatively simple and transparent tool for the comparison of the gasification reactivity of different fuels in fluidized bed gasification. The residence times for solid fuels in fluidized bed gasifiers are simulated. Simulations against some pilot-scale results show reasonable agreement. (orig.)

Sulfur Release during Alternative fuels Combustion in Cement Rotary Kilns

DEFF Research Database (Denmark)

Cortada Mut, Maria del Mar

fuel with the bed material, heating up of a particle, 5 iv devolatilization, char combustion, the reactions between CaSO 4 and the different reducing agents, and the oxidation of the volatiles gases in the free board. The main reducing agents are CO, CH 4 and H 2 , which are introduced under the bed...... are of high importance for SO 2 release because it is shown that introducing the same total amount of gas, the highest reducing agent concentration fo r a short period released a higher total SO 2 amount compared to the lowest concentration during a long period. A mathematical reaction based model...... but the effect of sulfur content in the bed cannot be predicted. Further development regarding particle motion according to the rotational speed may be needed. Furthermore, a model for predicting the tendency of build-ups for a kiln system is developed based on the prediction of SO 3 and Cl concentrations...

Valorization of algal waste via pyrolysis in a fixed-bed reactor: Production and characterization of bio-oil and bio-char.

Science.gov (United States)

Aboulkas, A; Hammani, H; El Achaby, M; Bilal, E; Barakat, A; El Harfi, K

2017-11-01

The aim of the present work is to develop processes for the production of bio-oil and bio-char from algae waste using the pyrolysis at controlled conditions. The pyrolysis was carried out at different temperatures 400-600°C and different heating rates 5-50°C/min. The algal waste, bio-oil and bio-char were successfully characterized using Elemental analysis, Chemical composition, TGA, FTIR, 1 H NMR, GC-MS and SEM. At a temperature of 500°C and a heating rate of 10°C/min, the maximum yield of bio-oil and bio-char was found to be 24.10 and 44.01wt%, respectively, which was found to be strongly influenced by the temperature variation, and weakly affected by the heating rate variation. Results show that the bio-oil cannot be used as bio-fuel, but can be used as a source of value-added chemicals. On the other hand, the bio-char is a promising candidate for solid fuel applications and for the production of carbon materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

The application of carbon isotope discrimination of charred wheat grains to reconstruct Late Holocene climate change and identify water management strategy in northwest China

Science.gov (United States)

Wang, W.; An, C.; Duan, F.; Zhao, Y.; Cao, Z.

2017-12-01

The AMS 14C dating and corresponding carbon stable isotope datum of charred wheat grains from archaeological sites in northwest China especially Hexi Corridor and Xinjiang have been collected widely to study its potential roles in reconstructing past climate change and identifying water management strategies through comparison with integrated regional humidity index, carbon isotope data of wheat grown under modern irrigation environment from study area and Mediterranean charred wheat carbon isotope data. The results suggest (1) carbon isotope discrimination values of charred wheat both in Hexi corridor and Xinjiang could respond well to regional moisture change, and there are also good positive correlation relationship between them (2) in contrast to consistent relationship between decreased carbon isotope discrimination values of charred wheat and dry climate condition, increased carbon isotope discrimination values does not represent wetter regional climate completely and may also reveal effects of human irrigation activities. The higher carbon isotope discrimination value of charred wheat which occurred in the Hexi Corridor from 4000 to 3850 a BP, 2100 a BP and 550 a BP and in Tianshan area of Xinjiang from 3730 a BP could be likely to be related with human activities (3) the carbon isotope discrimination value of charred wheat may have a certain limit which is generally not beyond 19‰. And this upper limit could influence its availability in reflecting abrupt change of precipitation/humidity especially rapid wetter trend. We conclude that carbon isotope analysis of charred wheat grains could be a good tool for reconstructing past climate change and identifying ancient irrigation practices.

The potential of activated carbon derived from bio-char waste of bio-oil pyrolysis as adsorbent

Directory of Open Access Journals (Sweden)

Zulkania Ariany

2018-01-01

Full Text Available Activated carbon from bio-char waste of bio oil pyrolysis of mixed sugarcane bagasse and Rambutan twigs was investigated. Bio-char as by-product of bio-oil pyrolysis has potential to be good adsorbed by activating process. Bio-chars waste was activated in fixed bed reactor inside furnace without presenting oxygen. Gas N2 and CO2 were employed to drive out oxygen from the reactor and as activator, respectively. One of the best activation treatments is achieved by performing activation in different temperature and time to produce standard activated carbon. The experiment was performed at different temperatures and activation time, i.e. 800, 850, and 900° C and 80 and 120 minutes, respectively, to determine the optimal operating condition. Activated carbon was characterized by analysis of moisture content, ash content pH, and methylene blue test. The results showed that optimum activation was at 850°C and 80 minute, where activated carbon produced indicated the best adsorption capacity. The ash content and pH had significant role in resulting good activated carbon.

Source profiles and contributions of biofuel combustion for PM2.5, PM10 and their compositions, in a city influenced by biofuel stoves.

Science.gov (United States)

Tian, Ying-Ze; Chen, Jia-Bao; Zhang, Lin-Lin; Du, Xin; Wei, Jin-Jin; Fan, Hui; Xu, Jiao; Wang, Hai-Ting; Guan, Liao; Shi, Guo-Liang; Feng, Yin-Chang

2017-12-01

Source and ambient samples were collected in a city in China that uses considerable biofuel, to assess influence of biofuel combustion and other sources on particulate matter (PM). Profiles and size distribution of biofuel combustion were investigated. Higher levels in source profiles, a significant increase in heavy-biomass ambient and stronger correlations of K + , Cl - , OC and EC suggest that they can be tracers of biofuel combustion. And char-EC/soot-EC (8.5 for PM 2.5 and 15.8 for PM 10 of source samples) can also be used to distinguish it. In source samples, water-soluble organic carbon (WSOC) were approximately 28.0%-68.8% (PM 2.5 ) and 27.2%-43.8% (PM 10 ) of OC. For size distribution, biofuel combustion mainly produces smaller particles. OC1, OC2, EC1 and EC2 abundances showed two peaks with one below 1 μm and one above 2 μm. An advanced three-way factory analysis model was applied to quantify source contributions to ambient PM 2.5 and PM 10 . Higher contributions of coal combustion, vehicular emission, nitrate and biofuel combustion occurred during the heavy-biomass period, and higher contributions of sulfate and crustal dust were observed during the light-biomass period. Mass and percentage contributions of biofuel combustion were significantly higher in heavy-biomass period. The biofuel combustion attributed above 45% of K + and Cl - , above 30% of EC and about 20% of OC. In addition, through analysis of source profiles and contributions, they were consistently evident that biofuel combustion and crustal dust contributed more to cation than to anion, while sulfate & SOC and nitrate showed stronger influence on anion than on cation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Slash-and-char: An ancient agricultural technique holds new promise for management of soils contaminated by Cd, Pb and Zn

International Nuclear Information System (INIS)

Niu, Li-qin; Jia, Pu; Li, Shao-peng; Kuang, Jia-liang; He, Xiao-xin; Zhou, Wen-hua; Liao, Bin; Shu, Wen-sheng; Li, Jin-tian

2015-01-01

Heavy metal contamination of agricultural soils is of worldwide concern. Unfortunately, there are currently no efficient and sustainable approaches for addressing this concern. In this study, we conducted a field experiment in which an agricultural soil highly contaminated by cadmium (Cd), lead (Pb) and zinc (Zn) was treated on-site by an ancient agricultural technique, ‘slash-and-char’, that was able to convert the biomass feedstock (rice straw) into biochar in only one day. We found evidence that in comparison to the untreated soil, the treated soil was associated with decreased bioavailability of the heavy metals and increased vegetable yields. Most importantly, the treatment was also coupled with dramatic reductions in concentrations of the heavy metals in vegetables, which made it possible to produce safe crops in this highly contaminated soil. Collectively, our results support the idea that slash-and-char offers new promise for management of soils contaminated by Cd, Pb and Zn. - Highlights: • We explored the potential of slash-and-char in dealing with soil metal pollution. • Metal bioavailability in the soil treated with slash-and-char was reduced by 24–65%. • Vegetable yield in the soil treated with slash-and-char was increased by 34–67%. • Slash-and-char could reduce the metal concentration in vegetables to a safe level. - An ancient agricultural technique called ‘slash-and-char’ offers new promise for management of soils contaminated multiply by Cd, Pb and Zn

Characterization of Oxy-combustion Impacts in Existing Coal-fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Adams, Bradley [Univ. of Utah, Salt Lake City, UT (United States); Davis, Kevin [Univ. of Utah, Salt Lake City, UT (United States); Senior, Constance [Univ. of Utah, Salt Lake City, UT (United States); Shim, Hong Shim [Univ. of Utah, Salt Lake City, UT (United States); Otten, Brydger Van [Univ. of Utah, Salt Lake City, UT (United States); Fry, Andrew [Univ. of Utah, Salt Lake City, UT (United States); Wendt, Jost [Univ. of Utah, Salt Lake City, UT (United States); Eddings, Eric [Univ. of Utah, Salt Lake City, UT (United States); Paschedag, Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shaddix, Christopher [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cox, William [Brigham Young Univ., Provo, UT (United States); Tree, Dale [Brigham Young Univ., Provo, UT (United States)

2013-09-30

Reaction Engineering International (REI) managed a team of experts from University of Utah, Siemens Energy, Praxair, Vattenfall AB, Sandia National Laboratories, Brigham Young University (BYU) and Corrosion Management Ltd. to perform multi-scale experiments, coupled with mechanism development, process modeling and CFD modeling, for both applied and fundamental investigations. The primary objective of this program was to acquire data and develop tools to characterize and predict impacts of CO{sub 2} flue gas recycle and burner feed design on flame characteristics (burnout, NO{sub x}, SO{sub x}, mercury and fine particle emissions, heat transfer) and operational concerns (fouling, slagging and corrosion) inherent in the retrofit of existing coal-fired boilers for oxy-coal combustion. Experimental work was conducted at Sandia National Laboratories’ Entrained Flow Reactor, the University of Utah Industrial Combustion Research Facility, and Brigham Young University. Process modeling and computational fluid dynamics (CFD) modeling was performed at REI. Successful completion of the project objectives resulted in the following key deliverables: 1) Multi-scale test data from 0.1 kW bench-scale, 100 kW and 200 kW laboratory-scale, and 1 MW semi-industrial scale combustors that describe differences in flame characteristics, fouling, slagging and corrosion for coal combustion under air-firing and oxygen-firing conditions, including sensitivity to oxy-burner design and flue gas recycle composition. 2) Validated mechanisms developed from test data that describe fouling, slagging, waterwall corrosion, heat transfer, char burnout and sooting under coal oxy-combustion conditions. The mechanisms were presented in a form suitable for inclusion in CFD models or process models. 3) Principles to guide design of pilot-scale and full-scale coal oxy-firing systems and flue gas recycle configurations, such that boiler operational impacts from oxy-combustion retrofits are minimized. 4

CharToon 2.1 extensions : expression repertoire and lip sync

OpenAIRE

Ruttkay, Z.M.; Lelièvre, Alban

2000-01-01

textabstractCharToon is a modular system to design and animate 21/2D faces and other graphic al objects. This report contains the extensions made for version 2.1, effecting only the Animation Editor module. The new features allow the re-usage of a reper toire of expression snapshots and animations and automatic generation of lip-syn c from phoneme and/or viseme sequences.

The influence of included minerals on the intrinsic reactivity of chars prepared under N{sub 2} and CO{sub 2} environment

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hong; Li, Huan; Chen, Jiabao; Zhao, Bo; Hu, Guangzhou [China Univ. of Mining and Technology, Jiangsu (China). School of Chemical Engineering

2013-07-01

Oxy-fuel technology could be successfully used to retrofit existing coal-fired power plants or alternatively be used to design and build new coal-fired power plants with almost zero emissions. Char reactivity under oxy-fuel conditions will have a significant impact on the coal burnout. In this paper, two fractions, representing organic-rich particles and organic particles with included minerals, were separated from each of three Chinese coals of different rank. They were then devolatilized at 1,450 C in a drop tube furnace (DTF) under N{sub 2} and CO{sub 2} environment, respectively. The chars were subjected to nitrogen adsorption study, thermogravimetric analysis and XRD analysis. It was found that char reactivity of all three pairs of chars were increased under CO{sub 2} environment as compared with that under N{sub 2} environment, but with differing trend. For the organic-rich samples the reactivity difference is increased with decreasing rank. On the contrary, for the samples of organic particles with included minerals, the reactivity difference is decreased with decreasing rank. Mechanism analysis showed that they are resulted not from gasification, but from a combination of changes in surface area and in the orderness of carbon structure in the chars, both of which, in turn, are resulted from the higher heat capacity of CO{sub 2} and the interaction between metastable liquid phase and the included minerals.

Combustion instability modeling and analysis

Energy Technology Data Exchange (ETDEWEB)

Santoro, R.J.; Yang, V.; Santavicca, D.A. [Pennsylvania State Univ., University Park, PA (United States); Sheppard, E.J. [Tuskeggee Univ., Tuskegee, AL (United States). Dept. of Aerospace Engineering

1995-12-31

It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO{sub x} emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors. The present study represents a coordinated effort between industry, government and academia to investigate gas turbine combustion dynamics. Specific study areas include development of advanced diagnostics, definition of controlling phenomena, advancement of analytical and numerical modeling capabilities, and assessment of the current status of our ability to apply these tools to practical gas turbine combustors. The present work involves four tasks which address, respectively, (1) the development of a fiber-optic probe for fuel-air ratio measurements, (2) the study of combustion instability using laser-based diagnostics in a high pressure, high temperature flow reactor, (3) the development of analytical and numerical modeling capabilities for describing combustion instability which will be validated against experimental data, and (4) the preparation of a literature survey and establishment of a data base on practical experience with combustion instability.

Analysis of Porous Structure Parameters of Biomass Chars Versus Bituminous Coal and Lignite Carbonized at High Pressure and Temperature—A Chemometric Study

Directory of Open Access Journals (Sweden)

Adam Smoliński

2017-09-01

Full Text Available The characteristics of the porous structure of carbonized materials affect their physical properties, such as density or strength, their sorption capacity, and their reactivity in thermochemical processing, determining both their applicability as fuels or sorbents and their efficiency in various processes. The porous structure of chars is shaped by the combined effects of physical and chemical properties of a carbonaceous material and the operating parameters applied in the carbonization process. In the study presented, the experimental dataset covering parameters of various fuels, ranging from biomass through lignite to bituminous coal, and chars produced at 1273 K and under the pressure of 1, 2, 3, and 4 MPa was analyzed with the application of the advanced method of data exploration. The principal component analysis showed that the sample of the highest coal rank was characterized by lower values of parameters reflecting the development of the porous structure of chars. A negative correlation was also observed between the carbon content in a fuel and the evolution of the porous structure of chars at high pressure. The highest total pore volume of chars produced under 1 and 3 MPa and the highest micropore surface area under 3 MPa were reported for a carbonized fuel sample of the highest moisture content.

Improvement in char formability of phenolic resin for development of Carbon/Carbon composites

International Nuclear Information System (INIS)

Hajhosseini, M.; Payami, A.; Ghaffarian, S. R.; Rezadoust, A. M.

2008-01-01

In the processing of carbon/carbon composites using polymer resin as the matrix precursor, it is inevitable that a porous structure was formed after carbonization. As a result, densification by liquid phase impregnation followed by recarbonization is required to obtain a densified composite. Consequently, the char formability of resin is an important factor in reducing the number of densification cycles and hence the processing cost. In this study, a novel approach is adopted to improve the densification of carbon/carbon composites by using a new phenolic resin modified by pitch. For this purpose, soluble part of pitch was extracted and dispersed in resol type phenolic resin. The polymerization reaction was performed in presence of para-formaldehyde and a resol-pitch compound was obtained. The second compound was prepared by mixing novolac-furfural in 55:45 weight ratio containing 9% by weight hexamethylene tetramine. This compound was added to resol-pitch compound in 10,20,50 and 80 w %. The microstructure of carbonized resin was investigated by X-ray diffraction and char yield, and the linear and volumetric shrinkage were obtained. Results show that in 80:20 ratio of resol-pitch to novolac-furfural , the char yield would be maximized by 71% and volumetric shrinkage would be minimized at 16.4%. At the same time, XRD results indicate that the resin has a strong ability to graphitize carbon/carbon composites matrix as a necessary step for its processing

Predictions of the impurities in the CO2 stream of an oxy-coal combustion plant

International Nuclear Information System (INIS)

Liu, Hao; Shao, Yingjuan

2010-01-01

furnace by the reburning mechanism and the char-NO reactions are the main reason for a smaller amount of NO x emitted by the oxy-coal combustion plant. The concentration of SO 2 in the flue gas of an oxy-coal combustion plant can be up to six times to that of an equivalent air-coal combustion plant if the recycling flue gas is not desulphurized. The flue gas volume flow rate of an oxy-coal combustion plant is much smaller (<20%) than that of an equivalent air-coal combustion plant, which is a significant advantage for the purification of the flue gas.

JV Task 125-Mercury Measurement in Combustion Flue Gases Short Course

Energy Technology Data Exchange (ETDEWEB)

Dennis Laudal

2008-09-30

The short course, designed to train personnel who have an interest in measuring mercury in combustion flue gases, was held twice at the Drury Inn in Marion, Illinois. The short course helped to provide attendees with the knowledge necessary to avoid the many pitfalls that can and do occur when measuring mercury in combustion flue gases. The first short course, May 5-8, 2008, included both a classroom-type session and hands-on demonstration of mercury-sampling equipment. The hands-on demonstration of equipment was staged at Southern Illinois Power Cooperative. Not including the Illinois Clean Coal Institute and the U.S. Department of Energy project managers, there were 12 attendees. The second short course was conducted September 16-17, 2008, but only included the classroom portion of the course; 14 people attended. In both cases, lectures were provided on the various mercury measurement methods, and interaction between attendees and EERC research personnel to discuss specific mercury measurement problems was promoted. Overall, the response to the course was excellent.

Study on demetalization of sewage sludge by sequential extraction before liquefaction for the production of cleaner bio-oil and bio-char.

Science.gov (United States)

Leng, Lijian; Yuan, Xingzhong; Shao, Jianguang; Huang, Huajun; Wang, Hou; Li, Hui; Chen, Xiaohong; Zeng, Guangming

2016-01-01

Demetalization of sewage sludge (SS) by sequential extraction before liquefaction was implemented to produce cleaner bio-char and bio-oil. Demetalization steps 1 and 2 did not cause much organic matter loss on SS, and thus the bio-oil and bio-char yields and the compositions of bio-oils were also not affected significantly. However, the demetalization procedures resulted in the production of cleaner bio-chars and bio-oils. The total concentrations and the acid soluble/exchangeable fraction (F1 fraction, the most toxic heavy metal fraction) of heavy metals (Cu, Cr, Pb, Zn, and Cd) in these products were significantly reduced and the environmental risks of these products were also relived considerably compared with those produced from raw SS, respectively. Additionally, these bio-oils had less heavy fractions. Demetalization processes with removal of F1 and F2 fractions of heavy metals would benefit the production of cleaner bio-char and bio-oil by liquefaction of heavy metal abundant biomass like SS. Copyright © 2015 Elsevier Ltd. All rights reserved.

Morphological changes during oxidation of a single char particle. Quarterly progress report, April 30, 1992

Energy Technology Data Exchange (ETDEWEB)

d`Amore, M. [Salerno Univ. (Italy). Dept. of Chemical and Food Engineering; Tognotti, L. [Pisa Univ. (Italy). Dept. of Chemical Engineering; Sarofim, A.F. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemical Engineering

1992-12-31

In this study, the changes with conversion in morphology of a carbon char in the temperature range 500--1200 K are followed by using an electrodynamic balance (EDB) (Spjut et al., 1985; Dudek, 1988; Bar-ziv et al., 1989). This device allows one to measure in situ, over temperature range wider than in other apparatuses, mass, diameter, density, surface area, rate of reaction and temperature for a single, suspended submillimeter particle. By following with the EDB the changes in the char as it reacts, it is possible to study the influence of the porous texture on the reaction behavior and shed some light on the contribution by micropores to the reaction in the chemical kinetic controlled regime.

Reforming sewage sludge pyrolysis volatile with Fe-embedded char: Minimization of liquid product yield.

Science.gov (United States)

Yu, Guotao; Chen, Dezhen; Arena, Umberto; Huang, Zhen; Dai, Xiaohu

2018-03-01

Obtaining high quality syngas from sewage sludge (SS) means transferring a low-grade SS into a high-grade fuel or raw materials for chemical products. In this study, Fe is added to SS in form of Fe 2 (SO 4 ) 3 to produce an effective and self-sufficient catalyst in order to obtain more syngas and minimize liquid products from SS pyrolysis. The Fe-embedded sewage sludge chars (SSCs) were used as catalysts for volatile reforming at 600°C. It has been found that the gas yield increases from 15.9 to 35.8wt% of the SS and that of liquids decreases from 31.9 to 10.2wt% after volatile reforming with Fe-embedded SSC when Fe was added equal to 7 % in the dried SS. In addition, the content of nitrogen-containing compounds in the oily products decreased. After reforming with Fe-embedded SSC, the molar fractions of syngas combustible components, including H 2 , CH 4 and CO, increase, and the higher heating value of the syngas increased to 17.0MJ/Nm 3 from the original 12.5MJ/Nm 3 obtained from SS pyrolysis at 550°C. Moreover, the volatile reforming seems to reduce the level of some important syngas pollutants, like H 2 S, HCl and HCN, even though it was also observed an increase of the contents of SO 2 , NH 3 , NO 2, HCNO and N 2 O. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shea meal and cotton stalk as potential fuels for co-combustion with coal.

Science.gov (United States)

Munir, S; Nimmo, W; Gibbs, B M

2010-10-01

The efficient management of waste biomass is an important environmental problem in agricultural countries. Often land-fill is the main disposal route with ramifications including CH(4) release having 21 times greater global warming potential per molecule than CO(2). Biomasses are considered to be CO(2)-neutral fuels when combusted. Moreover, they are renewable and covered by the renewable obligation scheme and eligible for certificates in the UK. The overall objective of the investigation is to assess the performance of selected biomass and coal co-firing under two different modes of operation, air-staging and fuel-staging with the benefit of reduced-NO(x) and SO(2) emissions in power plant. The biomasses chosen for the study, shea meal (SM) and cotton stalk (CS) have very different cellulose/lignin compositions and different reported thermal behaviour. A series of experiments have been carried out in a 20 kW, down fired combustor using coal, shea meal-coal and cotton stalk-coal blends under un-staged, air-staged and fuel-staged co-combustion configurations. For air-staging, an optimum value of primary zone stoichiometry SR(1)=0.9 was found. Keeping it fixed, the shea meal and cotton stalk content in the coal-biomass blends was set to 5%, 10% and 15% on thermal basis. NO reductions of 51% and 60% were achieved using SM and CS, respectively, with an optimum thermal biomass blending ratio (BBR) of 10%. The results obtained were compared with un-staged and air-staged results for coal without the addition of biomass. Similarly for fuel-staging, keeping the length of the reburn and burnout zone fixed, SM and CS were evaluated as reductive fuel using different reburn fuel fractions (R(ff)) of 5%, 10%, 15% and 20%. NO reductions of 83% and 84% were obtained with an optimum R(ff) of 15% with an optimum reburn zone stoichiometry of SR(2)=0.8 for both SM and CS, respectively. SO(2) reduction and char burnout efficiency were also evaluated. It was found that addition of

Emissions and Char Quality of Flame-Curtain "Kon Tiki" Kilns for Farmer-Scale Charcoal/Biochar Production

Science.gov (United States)

Cornelissen, Gerard; Pandit, Naba Raj; Taylor, Paul; Pandit, Bishnu Hari; Sparrevik, Magnus; Schmidt, Hans Peter

2016-01-01

Flame Curtain Biochar Kilns Pyrolysis of organic waste or woody materials yields charcoal, a stable carbonaceous product that can be used for cooking or mixed into soil, in the latter case often termed "biochar". Traditional kiln technologies for charcoal production are slow and without treatment of the pyrolysis gases, resulting in emissions of gases (mainly methane and carbon monoxide) and aerosols that are both toxic and contribute to greenhouse gas emissions. In retort kilns pyrolysis gases are led back to a combustion chamber. This can reduce emissions substantially, but is costly and consumes a considerable amount of valuable ignition material such as wood during start-up. To overcome these problems, a novel type of technology, the Kon-Tiki flame curtain pyrolysis, is proposed. This technology combines the simplicity of the traditional kiln with the combustion of pyrolysis gases in the flame curtain (similar to retort kilns), also avoiding use of external fuel for start-up. Biochar Characteristics A field study in Nepal using various feedstocks showed char yields of 22 ± 5% on a dry weight basis and 40 ± 11% on a C basis. Biochars with high C contents (76 ± 9%; n = 57), average surface areas (11 to 215 m2 g-1), low EPA16—PAHs (2.3 to 6.6 mg kg-1) and high CECs (43 to 217 cmolc/kg)(average for all feedstocks, mainly woody shrubs) were obtained, in compliance with the European Biochar Certificate (EBC). Gas Emission Factors Mean emission factors for the flame curtain kilns were (g kg-1 biochar for all feedstocks); CO2 = 4300 ± 1700, CO = 54 ± 35, non-methane volatile organic compounds (NMVOC) = 6 ± 3, CH4 = 30 ± 60, aerosols (PM10) = 11 ± 15, total products of incomplete combustion (PIC) = 100 ± 83 and NOx = 0.4 ± 0.3. The flame curtain kilns emitted statistically significantly (p<0.05) lower amounts of CO, PIC and NOx than retort and traditional kilns, and higher amounts of CO2. Implications With benefits such as high quality biochar, low emission

Thermal characteristics and surface morphology of char during co-pyrolysis of low-rank coal blended with microalgal biomass: Effects of Nannochloropsis and Chlorella.

Science.gov (United States)

Wu, Zhiqiang; Yang, Wangcai; Yang, Bolun

2018-02-01

In this work, the influence of Nannochloropsis and Chlorella on the thermal behavior and surface morphology of char during the co-pyrolysis process were explored. Thermogravimetric and iso-conversional methods were applied to analyzing the pyrolytic and kinetic characteristics for different mass ratios of microalgae and low-rank coal (0, 3:1, 1:1, 1:3 and 1). Fractal theory was used to quantitatively determine the effect of microalgae on the morphological texture of co-pyrolysis char. The result indicated that both the Nannochloropsis and Chlorella promoted the release of volatile from low-rank coal. Different synergistic effects on the thermal parameters and yield of volatile were observed, which could be attributed to the different compositions in the Nannochloropsis and Chlorella and operating condition. The distribution of activation energies shows nonadditive characteristics. Fractal dimensions of the co-pyrolysis char were higher than the individual char, indicating the promotion of disordered degree due to the addition of microalgae. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterisation of fuels for advanced pressurized combustion

Energy Technology Data Exchange (ETDEWEB)

Zevenhoven, R.; Hupa, M.; Backman, P.; Karlsson, M.; Kullberg, M.; Sorvari, V. [Aabo Akademi, Turku (Finland); Nurk, M. [Tallinn Univ. (Estonia)

1996-12-01

After 2 of the 3 years for this EU Joule 2 extension project, a rough comparison on the devolatilisation behaviour and char reactivity of 11 fossil fuels and 4 biofuels has been obtained. The experimental plan for 1995 has been completed, the laboratory facilities appeared to be well suited for the broad range of analyses presented here. A vast amount of devolatilisation tests in nitrogen at atmospheric pressure with gas analysis and char analysis gave a lot of information on the release of carbon, sulphur, nitrogen and also sodium, chloride and some other elements. Also first-order rate parameters could be determined. Solid pyrolysis yield measurements with the pressurised grid heater show a very good reproducibility except for the fuels with high carbonate content and those with very small char yield. Problems have to be solved considering lower heating rates and the use of folded grids. Fuel pyrolysis followed by gasification (with carbon dioxide or water as oxidising agent) at various temperatures and pressures shows that in general char solid yields and gasification reactivities are higher at elevated pressure. The design and construction of a pressurized single particle reactor, to be operational early 1996 is currently being negotiated. Numerical modelling of coal devolatilisation shows that even for atmospheric pressures the results differ significantly from experimental findings. (author)

Promotion of hydrogen-rich gas and phenolic-rich bio-oil production from green macroalgae Cladophora glomerata via pyrolysis over its bio-char.

Science.gov (United States)

Norouzi, Omid; Jafarian, Sajedeh; Safari, Farid; Tavasoli, Ahmad; Nejati, Behnam

2016-11-01

Conversion of Cladophora glomerata (C. glomerata) as a Caspian Sea's green macroalgae into gaseous, liquid and solid products was carried out via pyrolysis at different temperatures to determine its potential for bio-oil and hydrogen-rich gas production for further industrial utilization. Non-catalytic tests were performed to determine the optimum condition for bio-oil production. The highest portion of bio-oil was retrieved at 500°C. The catalytic test was performed using the bio-char derived at 500°C as a catalyst. Effect of the addition of the algal bio-char on the composition of the bio-oil and also gaseous products was investigated. Pyrolysis derived bio-char was characterized by BET, FESEM and ICP method to show its surface area, porosity, and presence of inorganic metals on its surface, respectively. Phenols were increased from 8.5 to 20.76area% by the addition of bio-char. Moreover, the hydrogen concentration and hydrogen selectivity were also enhanced by the factors of 1.37, 1.59 respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combustion technology developments in power generation in response to environmental challenges

Energy Technology Data Exchange (ETDEWEB)

BeerBeer, J.M. [Massachusetts Inst. of Technology, Dept. of Chemical Engineering, Cambridge, MA (United States)

2000-07-01

Combustion system development in power generation is discussed ranging from the pre-environmental era in which the objectives were complete combustion with a minimum of excess air and the capability of scale up to increased boiler unit performances, through the environmental era (1970-), in which reduction of combustion generated pollution was gaining increasing importance, to the present and near future in which a combination of clean combustion and high thermodynamic efficiency is considered to be necessary to satisfy demands for CO{sub 2} emissions mitigation. From the 1970's on, attention has increasingly turned towards emission control technologies for the reduction of oxides of nitrogen and sulfur, the so-called acid rain precursors. By a better understanding of the NO{sub x} formation and destruction mechanisms in flames, it has become possible to reduce significantly their emissions via combustion process modifications, e.g. by maintaining sequentially fuel-rich and fuel-lean combustion zones in a burner flame or in the combustion chamber, or by injecting a hydrocarbon rich fuel into the NO{sub x} bearing combustion products of a primary fuel such as coal. Sulfur capture in the combustion process proved to be more difficult because calcium sulfate, the reaction product of SO{sub 2} and additive lime, is unstable at the high temperature of pulverised coal combustion. It is possible to retain sulfur by the application of fluidised combustion in which coal burns at much reduced combustion temperatures. Fluidised bed combustion is, however, primarily intended for the utilisation of low grade, low volatile coals in smaller capacity units, which leaves the task of sulfur capture for the majority of coal fired boilers to flue gas desulfurisation. During the last decade, several new factors emerged which influenced the development of combustion for power generation. CO{sub 2} emission control is gaining increasing acceptance as a result of the international

Adding the combination of CNTs and MoS{sub 2} into halogen-free flame retarding TPEE with enhanced the anti-dripping behavior and char forming properties

Energy Technology Data Exchange (ETDEWEB)

Zhong, Yuhua; Li, Maolin; Zhang, Luchong; Zhang, Xuewei; Zhu, Songwei; Wu, Wei, E-mail: wuwei@ecust.edu.cn

2015-08-10

Highlights: • Introduction the combination of the CNTs and MoS{sub 2} into P–N flame retarding TPEE. • Binary synergists for P–N flame retardants in TPEE. • Increase of char yield and form the stable carbonaceous char. - Abstract: In this paper, the nanocomposites thermoplastic polyester-ether elastomer (TPEE) with phosphorus–nitrogen (P–N) flame retardants, carbon nanotubes (CNTs) and molybdenum disulfide (MoS{sub 2}) was prepared by melt blending. TPEE containing P–N flame retardant, CNTs and MoS{sub 2} achieved UL94 V-0 rating due to the better barrier effect of the special structure. The structure was supported by the result of rheological properties. The thermal stability was studied by thermal gravimetric analysis (TGA) and char residue characterization was investigated by SEM–EDX measurements. The results demonstrated that the combination of CNTs and MoS{sub 2} results in the increase of char yield and the formation of the thermally stable char which can effectively prevent in the dripping behavior during the burning process.

Mineral-char interaction during gasification of high-ash coals in fluidized-bed gasification

CSIR Research Space (South Africa)

Oboirien, BO

2011-09-01

Full Text Available -enriched conditions, while X-ray spectroscopy [and energy-dispersive spectrometry (EDS)] mapping was used to determine the distribution of elements, such as Si, Al, Mg, Ca, and K, in the same chars. The higher ordered structure of the carbon around the melted minerals...

Suprasubduction volcanic rocks of the Char ophiolite belt, East Kazakhstan: new geochemical and first geochronological data

Science.gov (United States)

Safonova, Inna; Simonov, Vladimir; Seltmann, Reimar; Yamamoto, Shinji; Xiao, Wenjiao

2016-04-01

The Char ophiolite belt is located in the western Central Asian Orogenic Belt, a world largest accretionary orogen, which has evolved during more than 800 Ma. The Char belt formed during Kazakhstan - Siberia collision. It has been known for hosting fragments of Late Devonian-Early Carboniferous oceanic crust, MORB, OPB and OIB, of the Paleo-Asian Ocean (Safonova et al., 2012). The Char is surrounded by two Paleozoic island-arc terranes: Zharma-Saur in the west and Rudny Altai in the east, however, until recent times, no island-arc units have been found within it. We were the first to find island-arc units as tectonic sheets occurring adjacent to those consisting of oceanic rocks. In places, island-arc andesites cut oceanic basalts. The Char volcanic and subvolcanic rocks of a probable suprasubduction origin are basalt, microgabbro, dolerite, andesite, tonalite and dacite. The mafic to andesitic volcanics possessing low TiO2 (0.85 wt.%av.) and show MgO vs. major elements crystallization trends suggesting two magma series: tholeiitic and calc-alkaline. The tholeiitic varieties are less enriched in incompatible elements then the calc-alkaline ones. Two samples are high-Mg and low-Ti andesibasalts similar to boninites. The rocks possess moderately LREE enriched rare-earth element patterns and are characterized by negative Nb anomalies present on the multi-element spectra (Nb/Lapm = 0.14-0.47; Nb/Thpm = 0.7-1.6).The distribution of rare-earth elements (La/Smn = 0.8-2.3, Gd/Ybn = 0.7-1.9) and the results of geochemical modeling in the Nb-Yb system suggest high degrees of melting of a depleted harzburgite-bearing mantle source at spinel facies depths. Fractional crystallization of clinopyroxene, plagioclase and opaque minerals also affected the final composition of the volcanic rocks. Clinopyroxene monomineral thermometry indicates crystallization of melts at 1020-1180°C. Melt inclusion composition based numerical calculations show that primary melts were derived at 1350

Co-pyrolysis behaviour and kinetic of two typical solid wastes in China and characterisation of activated carbon prepared from pyrolytic char.

Science.gov (United States)

Ma, Yuhui; Niu, Ruxuan; Wang, Xiaona; Wang, Qunhui; Wang, Xiaoqiang; Sun, Xiaohong

2014-11-01

This is the first study on the co-pyrolysis of spent substrate of Pleurotus ostreatus and coal tar pitch, and the activated carbon prepared from the pyrolytic char. Thermogravimetry (TG) analysis was carried out taking spent substrate, coal tar pitch and spent substrate-coal tar pitch mixture. The activation energies of pyrolysis reactions were obtained via the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods. The kinetic models were determined by the master-plots method. The activated carbons were characterised by N2-adsorption, Fourier transform infrared spectroscopy and X-ray diffraction. Experimental results demonstrated a synergistic effect happened during co-pyrolysis, which was characterised by a decreased maximum decomposition rate and an enhanced char yield. The average activation energies of the pyrolysis reactions of spent substrate, coal tar pitch and the mixture were 115.94, 72.92 and 94.38 kJ mol(-1) for the Flynn-Wall-Ozawa method, and 112.17, 65.62 and 89.91 kJ mol(-1) for the Kissinger-Akahira-Sunose method. The reaction model functions were f(α) = (1-α)(3.42), (1-α)(1.72) and (1-α)(3.07) for spent substrate, coal tar pitch and the mixture, respectively. The mixture char-derived activated carbon had a Brunauer-Emmett-Teller surface area up to 1337 m(2) g(-1) and a total pore volume of 0.680 cm(3) g(-1). Mixing spent substrate with coal tar pitch led to the creation of more micropores and a higher surface area compared with the single spent substrate and coal tar pitch char. Also, the mixture char-derived activated carbon had a higher proportion of aromatic stacking. This study provides a reference for the utilisation of spent substrate and coal tar pitch via co-pyrolysis, and their pyrolytic char as a promising precursor of activated carbon. © The Author(s) 2014.

Characterisation of coal and chars in fluidised bed gasification

CSIR Research Space (South Africa)

Oboirien, BO

2009-03-01

Full Text Available impact on the physical structure of the residual char. 4 In summary, the distinct burnout characteristics of coals could be attributed to the differences in the macerals and microlithotypes compositions, and mineral matter distribution....0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 REFLECTANCE % RE LA TIV E FR EQ UE NC Y % Increasing reflectance, decreasing volatiles, expected Increase in ignition temperature and time for burn-out Figure...

Gasification in pulverized coal flames. Final report (Part I). Pulverized coal combustion and gasification in a cyclone reactor: experiment and model

Energy Technology Data Exchange (ETDEWEB)

Barnhart, J. S.; Laurendeau, N. M.

1979-05-01

A unified experimental and analytical study of pulverized coal combustion and low-BTU gasification in an atmospheric cyclone reactor was performed. Experimental results include several series of coal combustion tests and a coal gasification test carried out via fuel-rich combustion without steam addition. Reactor stability was excellent over a range of equivalence ratios from .67 to 2.4 and air flowrates from 60 to 220 lb/hr. Typical carbon efficiencies were 95% for air-rich and stoichiometric tests and 80% for gasification tests. The best gasification results were achieved at an equivalence ratio of 2.0, where the carbon, cold gas and hot gas efficiencies were 83, 45 and 75%, respectively. The corresponding product gas heating value was 70 BTU/scf. A macroscopic model of coal combustion in the cyclone has been developed. Fuel-rich gasification can also be modeled through a gas-phase equilibrium treatment. Fluid mechanics are modeled by a particle force balance and a series combination of a perfectly stirred reactor and a plug flow reactor. Kinetic treatments of coal pyrolysis, char oxidation and carbon monoxide oxidation are included. Gas composition and temperature are checked against equilibrium values. The model predicts carbon efficiency, gas composition and temperature and reactor heat loss; gasification parameters, such as cold and hot gas efficiency and make gas heating value, are calculated for fuel-rich conditions. Good agreement exists between experiment and theory for conditions of this investigation.

Control of the low-load region in partially premixed combustion

Science.gov (United States)

Ingesson, Gabriel; Yin, Lianhao; Johansson, Rolf; Tunestal, Per

2016-09-01

Partially premixed combustion (PPC) is a low temperature, direct-injection combustion concept that has shown to give promising emission levels and efficiencies over a wide operating range. In this concept, high EGR ratios, high octane-number fuels and early injection timings are used to slow down the auto-ignition reactions and to enhance the fuel and are mixing before the start of combustion. A drawback with this concept is the combustion stability in the low-load region where a high octane-number fuel might cause misfire and low combustion efficiency. This paper investigates the problem of low-load PPC controller design for increased engine efficiency. First, low-load PPC data, obtained from a multi-cylinder heavy- duty engine is presented. The data shows that combustion efficiency could be increased by using a pilot injection and that there is a non-linearity in the relation between injection and combustion timing. Furthermore, intake conditions should be set in order to avoid operating points with unfavourable global equivalence ratio and in-cylinder temperature combinations. Model predictive control simulations were used together with a calibrated engine model to find a gas-system controller that fulfilled this task. The findings are then summarized in a suggested engine controller design. Finally, an experimental performance evaluation of the suggested controller is presented.

Experimental Investigation and High Resolution Simulation of In-Situ Combustion Processes

Energy Technology Data Exchange (ETDEWEB)

Margot Gerritsen; Tony Kovscek

2008-04-30

This final technical report describes work performed for the project 'Experimental Investigation and High Resolution Numerical Simulator of In-Situ Combustion Processes', DE-FC26-03NT15405. In summary, this work improved our understanding of in-situ combustion (ISC) process physics and oil recovery. This understanding was translated into improved conceptual models and a suite of software algorithms that extended predictive capabilities. We pursued experimental, theoretical, and numerical tasks during the performance period. The specific project objectives were (i) identification, experimentally, of chemical additives/injectants that improve combustion performance and delineation of the physics of improved performance, (ii) establishment of a benchmark one-dimensional, experimental data set for verification of in-situ combustion dynamics computed by simulators, (iii) develop improved numerical methods that can be used to describe in-situ combustion more accurately, and (iv) to lay the underpinnings of a highly efficient, 3D, in-situ combustion simulator using adaptive mesh refinement techniques and parallelization. We believe that project goals were met and exceeded as discussed.

Characterization and Activation Study of Black Chars Derived from Cellulosic Biomass Pyrolyzed at Very High Temperature

Energy Technology Data Exchange (ETDEWEB)

Contescu, Cristian I. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Gallego, Nidia C. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

2017-03-01

The State of Tennessee, in partnership with the University of Tennessee (UT) and the Oak Ridge National Laboratory (ORNL), has created the RevV! Manufacturing voucher program to help Tennessee manufacturers gain access to the world-class resources at ORNL. As a part of this program, ORNL was working with Proton Power, Inc. (PPI), a rapidly growing company located in Lenoir City, Tennessee. PPI has developed a patented renewable energy system that uses biomass and waste sources to produce inexpensive hydrogen gas or synthetic fuels which are economically competitive with fossil fuels. The pyrolysis process used by PPI in their manufacturing chain generates significant amounts of black carbon char as by-product. The scope of ORNL collaboration with PPI was assessing the black carbon char as a potential feedstock for activated carbon production, as this could be a potentially new revenue stream. During 2015-2016 ORNL received eight char samples from PPI and characterized their initial properties, simulated their physical activation by carbon dioxide, prepared gram-size samples of physically activated carbons, and characterized their surface and porosity properties. This report presents a summary of the work methods employed and the results obtained in the collaborative project between ORNL and PPI.

Development and Testing of Industrial Scale Coal Fired Combustion System, Phase 3

Energy Technology Data Exchange (ETDEWEB)

Bert Zauderer

1998-09-30

Coal Tech Corp's mission is to develop, license & sell innovative, lowest cost, solid fuel fired power systems & total emission control processes using proprietary and patented technology for domestic and international markets. The present project 'DEVELOPMENT & TESTING OF INDUSTRIAL SCALE, COAL FIRED COMBUSTION SYSTEM, PHASE 3' on DOE Contract DE-AC22-91PC91162 was a key element in achieving this objective. The project consisted of five tasks that were divided into three phases. The first phase, 'Optimization of First Generation 20 MMBtu/hr Air-Cooled Slagging Coal Tech Combustor', consisted of three tasks, which are detailed in Appendix 'A' of this report. They were implemented in 1992 and 1993 at the first generation, 20 MMBtu/hour, combustor-boiler test site in Williamsport, PA. It consisted of substantial combustor modifications and coal-fired tests designed to improve the combustor's wall cooling, slag and ash management, automating of its operation, and correcting severe deficiencies in the coal feeding to the combustor. The need for these changes was indicated during the prior 900-hour test effort on this combustor that was conducted as part of the DOE Clean Coal Program. A combination of combustor changes, auxiliary equipment changes, sophisticated multi-dimensional combustion analysis, computer controlled automation, and series of single and double day shift tests totaling about 300 hours, either resolved these operational issues or indicated that further corrective changes were needed in the combustor design. The key result from both analyses and tests was that the combustor must be substantially lengthened to maximize combustion efficiency and sharply increase slag retention in the combustor. A measure of the success of these modifications was realized in the third phase of this project, consisting of task 5 entitled: 'Site Demonstration with the Second Generation 20 MMBtu/hr Air-Cooled Slagging Coal Tech

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

Efficient Air Desulfurization Catalysts Derived from Pig Manure Liquefaction Char

Directory of Open Access Journals (Sweden)

Rajiv Wallace

2017-11-01

Full Text Available Biochar from the liquefaction of pig manure was used as a precursor of H2S desulfurization adsorbents. In its inorganic matter, it contains marked quantities of calcium, magnesium and iron, which are known as hydrogen sulfide oxidation catalysts. The char was used either as-received or mixed with 10% nanographite. The latter was added to increase both the content of the carbon phase and conductivity. ZnCl2 in two different ratios of char to an activation agent (1:1 and 1:2 was used to create the porosity in the carbon phase. The content of the later was between 18–45%. The activated samples adsorbed 144 mg/g H2S. Sulfur was the predominant product of reactive adsorption. Its deposition in the pore system and blockage of the most active pores ceased the materials’ activity. The presence of the catalytic phase was necessary but not sufficient to guarantee good performance. The developed porosity, which can store oxidation products in the resulting composite, is essential for the good performance of the desulfurization process. The surface of the composite with nanographite showed the highest catalytic activity, similar to that of the commercial Midas® carbon catalyst. The results obtained indicate that a high quality reactive adsorbent/catalyst for H2S removal can be obtained from pig manure liquefaction wastes.

Use of image analysis on the prediction of coal burnout performance in a drop tube furnace

Energy Technology Data Exchange (ETDEWEB)

R. Barranco; M. Cloke; E. Lester [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, SChEME

2003-07-01

An experimental investigation in a drop-tube furnace (DTF) into the combustion burnout performance of some South American coals was carried out. The coal samples, mainly from Colombia, were crushed and screened into three size fractions: 53-75 {mu}m, 106-125 {mu}m, and 150-180 {mu}m. These samples were characterised by standard tests along with a specially developed image analysis technique (grey-scale histogram). Pyrolysis of these samples was performed at a temperature of 1300{sup o}C, in a 1% of oxygen in nitrogen atmosphere for 200 ms. The chars obtained were then re-fired in the same apparatus, at the same temperature, at various residence times, in an atmosphere containing 5% of oxygen in nitrogen. The changes in the characteristics of the chars produced were assessed using a number of different techniques including intrinsic reactivity test and automatic char analysis. Despite the fact that all the coals used in this study were vitrinite-rich, variations in char morphology were evident. This demonstrated that it was impossible to assign any one char type to a single maceral group. It was apparent that vitrinite generates a wide range of char types depending upon the rank of the parent coal and on the maceral associations within the coal. In addition, a reactivity parameter, derived from the grey-scale histogram obtained by image analysis of the coal, was found to be important in the prediction of coal combustion behaviour. Some properties of the re-fired chars were compared with morphology and intrinsic reactivity data of the pyrolysed chars. The results showed that the poor burnout of one of the coals was clearly due to the formation of some particular chars during pyrolysis. This confirms the usefulness of high temperature pyrolysis chars as a predictor of burnout performance. 18 refs., 8 figs., 2 tabs.

Dust Combustion Safety Issues for Fusion Applications

Energy Technology Data Exchange (ETDEWEB)

L. C. Cadwallader

2003-05-01

This report summarizes the results of a safety research task to identify the safety issues and phenomenology of metallic dust fires and explosions that are postulated for fusion experiments. There are a variety of metal dusts that are created by plasma erosion and disruptions within the plasma chamber, as well as normal industrial dusts generated in the more conventional equipment in the balance of plant. For fusion, in-vessel dusts are generally mixtures of several elements; that is, the constituent elements in alloys and the variety of elements used for in-vessel materials. For example, in-vessel dust could be composed of beryllium from a first wall coating, tungsten from a divertor plate, copper from a plasma heating antenna or diagnostic, and perhaps some iron and chromium from the steel vessel wall or titanium and vanadium from the vessel wall. Each of these elements has its own unique combustion characteristics, and mixtures of elements must be evaluated for the mixture’s combustion properties. Issues of particle size, dust temperature, and presence of other combustible materials (i.e., deuterium and tritium) also affect combustion in air. Combustion in other gases has also been investigated to determine if there are safety concerns with “inert” atmospheres, such as nitrogen. Several coolants have also been reviewed to determine if coolant breach into the plasma chamber would enhance the combustion threat; for example, in-vessel steam from a water coolant breach will react with metal dust. The results of this review are presented here.

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.

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 ...

Understanding how lake populations of arctic char are structured and function with special consideration of the potential effects of climate change: a multi-faceted approach.

Science.gov (United States)

Budy, Phaedra; Luecke, Chris

2014-09-01

Size dimorphism in fish populations, both its causes and consequences, has been an area of considerable focus; however, uncertainty remains whether size dimorphism is dynamic or stabilizing and about the role of exogenous factors. Here, we explored patterns among empirical vital rates, population structure, abundance and trend, and predicted the effects of climate change on populations of arctic char (Salvelinus alpinus) in two lakes. Both populations cycle dramatically between dominance by small (≤300 mm) and large (>300 mm) char. Apparent survival (Φ) and specific growth rates (SGR) were relatively high (40-96%; SGR range 0.03-1.5%) and comparable to those of conspecifics at lower latitudes. Climate change scenarios mimicked observed patterns of warming and resulted in temperatures closer to optimal for char growth (15.15 °C) and a longer growing season. An increase in consumption rates (28-34%) under climate change scenarios led to much greater growth rates (23-34%). Higher growth rates predicted under climate change resulted in an even greater predicted amplitude of cycles in population structure as well as an increase in reproductive output (Ro) and decrease in generation time (Go). Collectively, these results indicate arctic char populations (not just individuals) are extremely sensitive to small changes in the number of ice-free days. We hypothesize years with a longer growing season, predicted to occur more often under climate change, produce elevated growth rates of small char and act in a manner similar to a "resource pulse," allowing a sub-set of small char to "break through," thus setting the cycle in population structure.

Recovery and Sequestration of CO2 from Stationary Combustion Systems by Photosynthesis of Microalgae

Energy Technology Data Exchange (ETDEWEB)

T. Nakamura; C.L. Senior

2005-04-01

Most of the anthropogenic emissions of carbon dioxide result from the combustion of fossil fuels for energy production. Photosynthesis has long been recognized as a means, at least in theory, to sequester anthropogenic carbon dioxide. Aquatic microalgae have been identified as fast growing species whose carbon fixing rates are higher than those of land-based plants by one order of magnitude. Physical Sciences Inc. (PSI), Aquasearch, and the Hawaii Natural Energy Institute at the University of Hawaii are jointly developing technologies for recovery and sequestration of CO{sub 2} from stationary combustion systems by photosynthesis of microalgae. The research is aimed primarily at demonstrating the ability of selected species of microalgae to effectively fix carbon from typical power plant exhaust gases. This report covers the reporting period 1 October 2000 to 31 March 2005 in which PSI, Aquasearch and University of Hawaii conducted their tasks. This report discusses results of the work pertaining to five tasks: Task 1--Supply of CO2 from Power Plant Flue Gas to Photobioreactor; Task 2--Selection of Microalgae; Task 3--Optimization and Demonstration of Industrial Scale Photobioreactor; Task 4--Carbon Sequestration System Design; and Task 5--Economic Analysis. Based on the work conducted in each task summary conclusion is presented.

Chars from gasification of coal and pine activated with K2CO3: acetaminophen and caffeine adsorption from aqueous solutions.

Science.gov (United States)

Galhetas, Margarida; Mestre, Ana S; Pinto, Moisés L; Gulyurtlu, Ibrahim; Lopes, Helena; Carvalho, Ana P

2014-11-01

The high carbon contents and low toxicity levels of chars from coal and pine gasification provide an incentive to consider their use as precursors of porous carbons obtained by chemical activation with K2CO3. Given the chars characteristics, previous demineralization and thermal treatments were made, but no improvement on the solids properties was observed. The highest porosity development was obtained with the biomass derived char (Pi). This char sample produced porous materials with preparation yields near 50% along with high porosity development (ABET≈1500m(2)g(-1)). For calcinations at 800°C, the control of the experimental conditions allowed the preparation of samples with a micropore system formed almost exclusively by larger micropores. A mesopore network was developed only for samples calcined at 900°C. Kinetic and equilibrium acetaminophen and caffeine adsorption data, showed that the processes obey to a pseudo-second order kinetic equation and to the Langmuir model, respectively. The results of sample Pi/1:3/800/2 outperformed those of the commercial carbons. Acetaminophen adsorption process was ruled by the micropore size distribution of the carbons. The caffeine monolayer capacities suggest a very efficient packing of this molecule in samples presenting monomodal micropore size distribution. The surface chemistry seems to be the determinant factor that controls the affinity of caffeine towards the carbons. Copyright © 2014 Elsevier Inc. All rights reserved.

FLEXIBLE, HIGH CHAR YIELD HYBRIDSIL ADHESIVE MATERIALS FOR NEXT GENERATION ABLATIVE THERMAL PROTECTION SYSTEMS, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NanoSonic will create and empirically validate flexible, high char yield HybridSil adhesive nanocomposites for use within current and next generation polymer based...

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.

Black liquor combustion validated recovery boiler modeling, five-year report

Energy Technology Data Exchange (ETDEWEB)

Grace, T.M.; Frederick, W.J.; Salcudean, M.; Wessel, R.A.

1996-08-01

The objective of this project was to develop a new computer model of a recovery boiler furnace using a computational fluid dynamics (CFD) code specifically tailored to the requirements for solving recovery boiler flows, and using improved submodels for black liquor combustion based on continued laboratory fundamental studies. The project originated in October 1990 and was scheduled to run for four years. At that time, there was considerable emphasis on developing accurate predictions of the physical carryover of macroscopic particles of partially burnt black liquor and smelt droplets out of the furnace, since this was seen as the main cause of boiler plugging. This placed a major emphasis on gas flow patterns within the furnace and on the mass loss rates and swelling and shrinking rates of burning black liquor drops. As work proceeded on developing the recovery boiler furnace model, it became apparent that some recovery boilers encounter serious plugging problems even when physical carryover was minimal. After the original four-year period was completed, the project was extended to address this issue. The objective of the extended project was to improve the utility of the models by including the black liquor chemistry relevant to air emissions predictions and aerosol formation, and by developing the knowledge base and computational tools to relate furnace model outputs to fouling and plugging of the convective sections of the boilers. The work done to date includes CFD model development and validation, acquisition of information on black liquor combustion fundamentals and development of improved burning models, char bed model development, and model application and simplification.