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Sample records for circulating fluidised bed

  1. Optimum diameter of a circulating fluidised bed combustor with negative wall heat flux

    CSIR Research Space (South Africa)

    Baloyi, J

    2015-07-01

    Full Text Available on irreversibilities in a 7 m circulating fluidised bed combustor with a negative wall heat flux, firing a mixture of air and solid pitch pine wood, was investigated. An analytical expression was derived that predicts the entropy generation rate, thereby...

  2. Bed-To-Wall Heat Transfer in a Supercritical Circulating Fluidised Bed Boiler

    Directory of Open Access Journals (Sweden)

    Błaszczuk Artur

    2014-06-01

    Full Text Available The purpose of this work is to find a correlation for heat transfer to walls in a 1296 t/h supercritical circulating fluidised bed (CFB boiler. The effect of bed-to-wall heat transfer coefficient in a long active heat transfer surface was discussed, excluding the radiation component. Experiments for four different unit loads (i.e. 100% MCR, 80% MCR, 60% MCR and 40% MCR were conducted at a constant excess air ratio and high level of bed pressure (ca. 6 kPa in each test run. The empirical correlation of the heat transfer coefficient in a large-scale CFB boiler was mainly determined by two key operating parameters, suspension density and bed temperature. Furthermore, data processing was used in order to develop empirical correlation ranges between 3.05 to 5.35 m·s-1 for gas superficial velocity, 0.25 to 0.51 for the ratio of the secondary to the primary air, 1028 to 1137K for bed temperature inside the furnace chamber of a commercial CFB boiler, and 1.20 to 553 kg·m-3 for suspension density. The suspension density was specified on the base of pressure measurements inside the boiler’s combustion chamber using pressure sensors. Pressure measurements were collected at the measuring ports situated on the front wall of the combustion chamber. The obtained correlation of the heat transfer coefficient is in agreement with the data obtained from typical industrial CFB boilers.

  3. Advanced circulating fluidised bed technology (CFB) for large-scale solid biomass fuel firing power plants

    Energy Technology Data Exchange (ETDEWEB)

    Jaentti, Timo; Zabetta, Edgardo Coda; Nuortimo, Kalle [Foster Wheeler Energia Oy, Varkaus (Finland)

    2013-04-01

    Worldwide the nations are taking initiatives to counteract global warming by reducing their greenhouse gas emissions. Efforts to increase boiler efficiency and the use of biomass and other solid renewable fuels are well in line with these objectives. Circulating fluidised bed boilers (CFB) are ideal for efficient power generation, capable to fire a broad variety of solid biomass fuels from small CHP plants to large utility power plants. Relevant boiler references in commercial operation are made for Finland and Poland.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-07-01

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

  5. A technical pilot plant assessment of flue gas desulfurisation in a circulating fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, F.J.; Ollero, P. [Universidad de Sevilla (Spain). Dept. de Ingenieria Quimica y Ambiental; Cabanillas, A.; Otero, J. [Centro de Investigaciones Energeticas y Medioambientales, (CIEMAT), Madrid (Spain)

    2002-11-01

    Flue gas desulfurisation in a circulating fluidised bed absorber (CFBA) is quite a novel dry desulfurisation technology [6th International Conference on Circulating Fluidised Beds (1999) 601] that shows significant advantages in comparison with other dry technologies and that could also be competitive with the widely-used wet FGD technology. This experimental study analyses the performance of a flue gas treatment plant comprising a CFBA and an electrostatic precipitator (ESP). The most significant aspects considered in this study are: the effect of precollecting the fly ash, the effect of the SO{sub 2} inlet concentration, the effect of power plant load changes, the contribution of the final particulate control equipment to the overall SO{sub 2} removal efficiency and the impact of the desulfurisation unit on the ESP behaviour and its final dust emissions. In addition, the behaviour of the integrated CFBA-ESP system with respect to the main operating parameters was studied by means of a fractional factorial design of experiments. All this experimental work was carried out in a 3-MWe equivalent pilot plant that processes real gases withdrawn from the Los Barrios Power Plant. Processing a flue gas with up to 2000 ppm SO{sub 2} concentration, a sulfur removal of 95-97% with a lime utilisation of 75% was achieved. A simple regression model to evaluate the efficiency of the whole system is also proposed.(author)

  6. Fluidised bed heat exchangers

    International Nuclear Information System (INIS)

    Elliott, D.E.; Healey, E.M.; Roberts, A.G.

    1974-01-01

    Problems that have arisen during the initial stages of development of fluidised bed boilers in which heat transfer surfaces are immersed in fluidised solids are discussed. The very high heat transfer coefficients that are obtained under these conditions can be exploited to reduce the total heat transfer surface to a fraction of that in normal boilers. However, with the high heat flux levels involved, tube stressing becomes more important and it is advantageous to use smaller diameter tubes. One of the initial problems was that the pumping power absorbed by the fluidised bed appeared to be high. The relative influence of the fluidising velocity (and the corresponding bed area), tube diameter, tube spacing, heat transfer coefficient and bed temperature on pumping power and overall cost was determined. This showed the importance of close tube packing and research was undertaken to see if this would adversely affect the heat transfer coefficient. Pressure operation also reduces the pumping power. Fouling and corrosion tests in beds burning coal suggest that higher temperatures could be reached reliably and cost studies show that, provided the better refractory metals are used, the cost of achieving higher temperatures is not unduly high. It now remains to demonstrate at large scale that the proposed systems are viable and that the methods incorporated to overcome start up and part lead running problems are satisfactory. The promising role of these heat transfer techniques in other applications is briefly discussed

  7. Fluidised bed cereal cooking

    International Nuclear Information System (INIS)

    Jenkins, Simon Anthony

    2002-01-01

    Man has been cooking food for thousands of years for a number of reasons: to improve flavour and palatability, sterilise, increase digestibility, improve texture and colour. Increasingly more advanced techniques are employed today in food production plants to engineer foods with many different properties. With this in mind manufacturers are constantly seeking to improve processing techniques and apply new or different technologies (such as microwaves, RF and extrusion) to develop foods with new properties (like puffed texture starches) and to increase process efficiencies (energy efficiency, water reduction). This thesis reports on work undertaken to demonstrate the potential to achieve high temperature starch conversion of whole wheat grains in a fluidised bed, thereby reducing the amount of water required and processing time. Specifically, wheat from the farm at 14% water content is cooked in a fluidised bed. The fluidised bed heats the wheat quickly by convective heating. In addition, energy can be delivered directly to the grain by microwave heating during fluidisation. Degree of starch conversion is determined by measuring the reduction in size of endotherm of reaction as observed by Differential Scanning Calorimetry. The fluidising gas, processing temperature and starting moisture content were varied in order to investigate their effect on the cooking process. A mathematical model based on energy and species concentration equations was developed to help understand the internal grain processes. The model coupled the thermal energy equation with water diffusion. The effect of water evaporation was represented as a thermal sink in the energy equation. Popular kinetic models from literature were adapted to predict the degree of starch conversion. The model gives solutions consistent with experimental data and physical intuition. A commercial computational fluid dynamics package was used to study simple airflow and particle tracks in the fluidisation column. A

  8. Sulphation of calcium-based sorbents in circulating fluidised beds under oxy-fuel combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Francisco Garcia-Labiano; Luis F. de Diego; Alberto Abad; Pilar Gayan; Margarita de las Obras-Loscertales; Aranzazu Rufas; Juan Adanez [Instituto de Carboquimica (CSIC), Zaragoza (Spain). Dept. Energy and Environment

    2009-07-01

    Sulphur Retention (SR) by calcium-based sorbents is a process highly dependent on the temperature and CO{sub 2} concentration. In circulating fluidised beds combustors (CFBC's) operating under oxy-fuel conditions, the sulphation process takes place in atmospheres enriched in CO{sub 2} with bed concentrations that can vary from 40 to 95%. Under so high CO{sub 2} concentrations, very different from that in conventional coal combustion atmosphere with air, the calcination and sulphation behaviour of the sorbent must be defined to optimise the SR process in the combustor. The objective of this work was to determine the SO{sub 2} retention capacity of a Spanish limestone at typical oxy-fuel conditions in CFBC's. Long term duration tests of sulphation (up to 24 h), to simulate the residence time of sorbents in CFBC's, were carried out by thermogravimetric analysis (TGA). Clear behaviour differences were found under calcining and non-calcining conditions. Especially relevant was the result obtained at calcining conditions but close to the thermodynamic temperature given for sorbent calcination. This situation must be avoided in CFBC's because the CO{sub 2} produced inside the particle during calcination can destroy the particles if a non-porous sulphate product layer has been formed around the particle. The effect of the main variables on the sorbent sulphation such as SO{sub 2} concentration, temperature, and particle size were analysed in the long term TGA tests. These data were also used to determine the kinetic parameters for the sulphation under oxy-fuel combustion conditions, which were able to adequately predict the sulphation conversion values in a wide range of operating conditions. 20 refs., 5 figs., 2 tabs.

  9. Fluidised bed combustion system

    International Nuclear Information System (INIS)

    McKenzie, E.C.

    1976-01-01

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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  11. Leaching Behavior of Circulating Fluidised Bed MSWI Air Pollution Control Residue in Washing Process

    Directory of Open Access Journals (Sweden)

    Zhiliang Chen

    2016-09-01

    Full Text Available In this study, air pollution control (APC residue is conducted with water washing process to reduce its chloride content. A novel electrical conductivily (EC measurement method is proposed to monitor the dynamic change of chloride concentrations in leachate as well as the chloride content of the residue. The method equally applies to various washing processes with different washing time, liquid/solid ratio and washing frequency. The results show that washing effectively extracts chloride salts from APC residues, including those from circulating fluidized bed (CFB municipal solid waste incineration (MSWI. The most appropriate liquid/solid ratio and washing time in the first washing are found to be around 4 L water per kg of APC residue and 30 min, respectively, and washing twice is required to obtain maximum dissolution. The pH value is the major controlling factor of the heavy metals speciation in leachate, while chloride concentration also affects the speciation of Cd. Water washing causes no perceptible transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs from the APC residue to leachate. The chloride concentration is strongly related with electrical conductivity (EC, as well as with the concentrations of calcium, sodium and potassium of washing water. Their regression analyses specify that soluble chloride salts and EC could act as an indirect indicator to monitor the change of chloride concentration and remaining chloride content, thus, contributing to the selection of the optimal washing conditions.

  12. Characterising boiler ash from a circulating fluidised bed municipal solid waste incinerator and distribution of PCDD/F and PCB.

    Science.gov (United States)

    Zhang, Mengmei; Buekens, Alfons; Li, Xiaodong

    2018-05-31

    In this study, ash samples were collected from five locations situated in the boiler of a circulating fluidised bed municipal solid waste incinerator (high- and low-temperature superheater, evaporator tubes and upper and lower economiser). These samples represent a huge range of flue gas temperatures and were characterised for their particle size distribution, surface characteristics, elemental composition, chemical forms of carbon and chlorine and distribution of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and biphenyls (PCB). Enrichment of chlorine, one of the main elements of organochlorinated pollutants, and copper, zinc and lead, major catalytic metals for dioxin-like compounds, was observed in lower-temperature ash deposits. The speciation of carbon and chlorine on ash surfaces was established, showing a positive correlation between organic chlorine and oxygen-containing carbon functional groups. The load of PCDD/F and PCB (especially dioxin-like PCB) tends to rise rapidly with falling temperature of flue gas, reaching their highest value in economiser ashes. The formation of PCDD/F congeners through the chlorophenol precursor route apparently was enhanced downstream the boiler. Principal component analysis (PCA) was applied to study the links between the ash characteristics and distribution of chloro-aromatics. The primary purpose of this study is improving the understanding of any links between the characteristics of ash from waste heat systems and its potential to form PCDD/F and PCB. The question is raised whether further characterisation of fly ash may assist to establish a diagnosis of poor plant operation, inclusive the generation, destruction and eventual emission of persistent organic pollutants (POPs).

  13. Fluidised-bed combustion of gasification residue

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  14. Solid phase transport in series fluidised bed reactors

    International Nuclear Information System (INIS)

    Hayes, M.R.

    1980-01-01

    In a multistage counter-current fluidised bed column, fluidised bed material is recycled within each stage and a fraction is continuously withdrawn to the next lower stage at a rate dependent only on the rate of removal of the fluidised bed material from the base of the column. It has a particular application to the ion exchange treatment of liquids containing suspended solids, for example leach solutions from uranium ores. (author)

  15. Thermodynamic optimisation and computational analysis of irreversibilities in a small-scale wood-fired circulating fluidised bed adiabatic combustor

    CSIR Research Space (South Africa)

    Baloyi, J

    2014-06-01

    Full Text Available parameters on energy and exergy characteristics and exergy losses. International Journal of Energy Research 2006; 30: 203-219. [24] Ziebik A, stanek W. Energy and exergy system analysis of thermal improvements of blast-furnace plants. International... in the riser column of a pressurized circulating fluidized bed. International Journal of Energy Research 2006; 30: 149-162. [27] Cihan A, Hacihafizoglu O, Kahveci K. Energy-exergy analysis and modenization suggestions for a combined-cycle power plant...

  16. Fungi solubilisation of low rank coal: performances of stirred tank, fluidised bed and packed bed reactors

    CSIR Research Space (South Africa)

    Oboirien, BO

    2013-02-01

    Full Text Available Coal biosolubilisation was investigated in stirred tank reactor, fluidised bed and fixed bed bioreactors with a view to highlight the advantages and shortcomings of each of these reactor configurations. The stirred aerated bioreactor and fluidised...

  17. A Three-Dimensional Numerical Study of Gas-Particle Flow and Chemical Reactions in Circulating Fluidised Bed Reactors

    DEFF Research Database (Denmark)

    Hansen, Kim Granly

    Three-dimensional Computational Fluid Dynamics (CFD) simulations of Circulating Fluidized Beds (CFB's) have been performed. The computations are performed using a 3D multiphase computational fluid dynamics code with an Eulerian description of both gas and particle phases. The turbulent motion...... implemented in the CFD code FLOTRACS-MP-3D. The decomposition reaction is studied in a 3D representation of a 0.254 m i.d. riser, which has been studied experimentally by Ouyang et al. (1993). Comparison between measured and simulated time-averaged ozone concentration at different elevations in the riser...

  18. Ruedersdorf cement works substitutes raw material and fuel by means of a circulating fluidised bed; Roh- und Brennstoffsubstitution mit einer Zirkulierenden Wirbelschicht im Zementwerk Ruedersdorf

    Energy Technology Data Exchange (ETDEWEB)

    Scur, P. [Ruedersdorfer Zement GmbH, Ruedersdorf (Germany)

    1998-09-01

    The purpose of the present paper is to point out the great potential the cement industry holds for the utilisation of waste materials. There are meanwhile sufficient studies and measuring results to demonstrate the environmental acceptability of the processes and products involved. The solution found for Ruedersdorf cement kiln of using a circulating a fluidised bed for waste utilisation is a good example of the potential still available for conserving natural resources and landfill area. Efficient industrial applications of this kind should become a future mainstay of the waste industry. [Deutsch] In dem vorliegenden Beitrag sollte gezeigt werden, dass die Zementindustrie ueber ein hohes Potential zur thermischen und stofflichen Verwertung von Abfallstoffen verfuegt. Es liegen ausreichende Untersuchungen und konkrete Messergebnisse vor, mit denen die Umweltvertraeglichkeit von Prozess und Produkt nachgewiesen werden kann. Die Loesung zur Abfallverwertung an der Ruedersdorfer Zementofenanlage mit Hilfe einer Zirkulierenden Wirbelschicht ist ein Beispiel fuer die Reserven zur Schonung natuerlicher Ressourcen und zur Einsparung von Deponieraeumen. Derartige sinnvolle industrielle Einsatzmoeglichkeiten sollten ein wichtiges Standbein fuer die zukuenftige Abfallwirtschaft sein. (orig.)

  19. VOC emission control by circulating fluidized bed adsorption; Controle de l'emission de composes organiques volatils par adsorption en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Song, W.

    2003-12-15

    This work deals with the circulating fluidized bed technology, applied to the elimination by adsorption of volatile organic compounds (VOCs), like toluene, in a gas flow. In the process, the adsorbent (millimetric spherical grains of micro-porous carbon) is moved by a strong flow rate of gas inside a vertical tube without lining. Mass and heat transfers are very important and important volumes of compounds can be processed. This work presents the determination of the adsorption equilibrium, the description of the experimental facility and of the results of experiments, the development of an original model of the process which combines a flow model and a mass transfer model, a parametric study of this model, and finally, some extensions of the process principle to staged operations with pressure variation or temperature variation cycles. (J.S.)

  20. Fluidised bed gasification of low grade South African coals

    CSIR Research Space (South Africa)

    North, BC

    2006-09-01

    Full Text Available gasifiers. Fluidised bed Entrained flow Coal particle size 0.5 mm – 5 mm 0 – 0.5 mm Coal moisture Dry Dry/slurry Coal type Non-caking coals Any coal Ash in coal < 60% < 30% Gasification agents Air/steam/oxygen Steam/oxygen Gasification... properties important for fluidised bed gasification are: square4 Coal reactivity in atmospheres of CO2 and H2O square4 Caking index and free swelling index (FSI) square4 Ash fusion temperature (AFT) 5.1 Coal reactivity The gasifcation reactions (1...

  1. Biofluid process: fluidised-bed gasification of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Dittrich, A. [ATEKO a.s., Hradec Kralove (Czech Republic)

    1996-12-31

    Fluidised-bed gasification of biomass was developed by ATEKO by using long-term experience from coal gasification. An experimental unit was built and a number of tests, first with sawdust gasification, were carried out. A gas combustion engine combined with a power generator was installed and operated in power production. (orig.)

  2. Biofluid process: fluidised-bed gasification of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Dittrich, A [ATEKO a.s., Hradec Kralove (Czech Republic)

    1997-12-31

    Fluidised-bed gasification of biomass was developed by ATEKO by using long-term experience from coal gasification. An experimental unit was built and a number of tests, first with sawdust gasification, were carried out. A gas combustion engine combined with a power generator was installed and operated in power production. (orig.)

  3. Coal. Fluidized bed, a world record; Charbon. Lit fluidise: record mondial

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    In April 1996, the `Societe Provencale du Lit Fluidise`, a subsidiary of Electricite de France (EDF) has put into service in Gardanne, the most powerful circulating fluidized bed boiler in the world, producing 600 MWt; it was constructed by GEC Alsthom Stein Industrie, and will strongly reduce the SO{sub 2} emissions from the coal power plant of Gardanne, which use a highly sulfurous coal. New regulations concerning the French coal industry are also introduced

  4. Coal. Fluidized bed, a world record; Charbon. Lit fluidise: record mondial

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    In April 1996, the `Societe Provencale du Lit Fluidise`, a subsidiary of Electricite de France (EDF) has put into service in Gardanne, the most powerful circulating fluidized bed boiler in the world, producing 600 MWt; it was constructed by GEC Alsthom Stein Industrie, and will strongly reduce the SO{sub 2} emissions from the coal power plant of Gardanne, which use a highly sulfurous coal. New regulations concerning the French coal industry are also introduced

  5. Modeling and Simulation of a lab-scale Fluidised Bed

    Directory of Open Access Journals (Sweden)

    Britt Halvorsen

    2002-04-01

    Full Text Available The flow behaviour of a lab-scale fluidised bed with a central jet has been simulated. The study has been performed with an in-house computational fluid dynamics (CFD model named FLOTRACS-MP-3D. The CFD model is based on a multi-fluid Eulerian description of the phases, where the kinetic theory for granular flow forms the basis for turbulence modelling of the solid phases. A two-dimensional Cartesian co-ordinate system is used to describe the geometry. This paper discusses whether bubble formation and bed height are influenced by coefficient of restitution, drag model and number of solid phases. Measurements of the same fluidised bed with a digital video camera are performed. Computational results are compared with the experimental results, and the discrepancies are discussed.

  6. Coal-char combustion in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-12-01

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

  7. 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

  8. 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

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

    CSIR Research Space (South Africa)

    Oboirien, BO

    2013-09-01

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

  10. Combustion of poultry litter in a fluidised bed combustor

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-04-01

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

  11. Experimental study of the mechanisms of CO{sub 2} capture by calcium cycle under circulating fluidized bed conditions; Etude experimentale des mecanismes de capture du CO{sub 2} par cycle calcium en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Hoteit, A

    2006-06-15

    The work undertaken in this Thesis in partnership with department R and D of ALSTOM Power Boilers, CEMEX and the ADEME, relates to the experimental study of various phenomena associated to CO{sub 2} capture under circulating fluidized bed conditions. The size of particles, temperature and the CO{sub 2} concentration have an influence on the limestone calcination reaction. The reaction of carbonation of lime is not total. During successive cycles of calcination/carbonation, the rate of carbonation obtained with hydrated lime is increasingly higher than that obtained with the lime. Under continuously reducing conditions, the decomposition of sulphates present in the bed ashes is not total. This decomposition is total under reduction/oxidation cycles. A modeling of calcination allowed to determine the intrinsic kinetic constants of calcination and carbonation. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-01

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

  13. Simulations of a Circulating Fluidized Bed Chemical Looping Combustion System Utilizing Gaseous Fuel; Simulation de la combustion en boucle chimique d'une charge gazeuse dans un lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Mahalatkar, K.; Kuhlman, J. [West Virginia University, Dept. of Mechanical and Aerospace Engineering, Morgantown, WV, 26506 (United States); Mahalatkar, K. [ANSYS Inc., 3647 Collins Ferry Road Suite A, Morgantown, WV, 26505 (United States); Kuhlman, J.; Huckaby, E.D.; O' Brien, T. [National Energy Technology Laboratory, 3610 Collins Ferry Road, Morgantown, WV, 26507 (United States)

    2011-03-15

    Numerical studies using Computational Fluid Dynamics (CFD) have been carried out for a complete circulating fluidized bed chemical looping combustor described in the literature (Abad et al., 2006 Fuel 85, 1174-1185). There have been extensive experimental studies in Chemical Looping Combustion (CLC), however CFD simulations of this concept are quite limited. The CLC experiments that were simulated used methane as fuel. A 2-D continuum model was used to describe both the gas and solid phases. Detailed sub-models to account for fluid-particle and particle-particle interaction forces were included. Global models of fuel and carrier chemistry were utilized. The results obtained from CFD were compared with experimental outlet species concentrations, solid circulation rates, solid mass distribution in the reactors, and leakage and dilution rates. The transient CFD simulations provided a reasonable match with the reported experimental data. (authors)

  14. Experimental measurement of variation of heat transfer coefficient and temperature gradients in 16'' deep fluidised beds

    International Nuclear Information System (INIS)

    Blacker, P.T.; McLain, D.R.

    1962-04-01

    The object of the experiments was to choose suitable particulate materials for a fluidised bed cooler, to test a deep fluidised bed for uniformity of heat transfer coefficient, and to explore the temperature distribution in a centrally heated annular fluidised bed. This memorandum records the techniques used and some of the practical aspects involved, together with the performance results obtained, for the assistance of other experimenters who may wish to use fluidised beds as a laboratory technique. Mathematical correlation of the results has not been attempted since some of the properties of the bed material were not known and to determine them was beyond the scope of the work programme. Rather, we have compared our results with those of other experimenters. Graphite tubes, for use in steady state thermal stress experiments, are to be heated by a graphite radiant heater situated in the bore and cooled on the outer surface. The tubes are 2 cm. bore, 8 cm. outside diameter and 48 cm. long. The outside temperature of the tubes is to be between 500 deg. C. and 1500 deg. C. It is estimated that the heat transfer rate required for fracture at the outer surface is 30 watts/cm 2 . This could readily be achieved by cooling with liquid metals, water or high velocity gas. However, serious problems of either materials compatibility or mechanical complexity make these undesirable. A water-cooled fluidised bed of compatible solids fluidised with nitrogen gas can overcome most of these problems and give heat transfer coefficients close to that required, vis. about 0.1 w/cm C . A coolant bed about 20'' long would be required and an annulus of about 2'' radial width round the specimen was considered to be practicable

  15. Experimental measurement of variation of heat transfer coefficient and temperature gradients in 16'' deep fluidised beds

    Energy Technology Data Exchange (ETDEWEB)

    Blacker, P T; McLain, D R [Reactor Development Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1962-04-15

    The object of the experiments was to choose suitable particulate materials for a fluidised bed cooler, to test a deep fluidised bed for uniformity of heat transfer coefficient, and to explore the temperature distribution in a centrally heated annular fluidised bed. This memorandum records the techniques used and some of the practical aspects involved, together with the performance results obtained, for the assistance of other experimenters who may wish to use fluidised beds as a laboratory technique. Mathematical correlation of the results has not been attempted since some of the properties of the bed material were not known and to determine them was beyond the scope of the work programme. Rather, we have compared our results with those of other experimenters. Graphite tubes, for use in steady state thermal stress experiments, are to be heated by a graphite radiant heater situated in the bore and cooled on the outer surface. The tubes are 2 cm. bore, 8 cm. outside diameter and 48 cm. long. The outside temperature of the tubes is to be between 500 deg. C. and 1500 deg. C. It is estimated that the heat transfer rate required for fracture at the outer surface is 30 watts/cm{sup 2}. This could readily be achieved by cooling with liquid metals, water or high velocity gas. However, serious problems of either materials compatibility or mechanical complexity make these undesirable. A water-cooled fluidised bed of compatible solids fluidised with nitrogen gas can overcome most of these problems and give heat transfer coefficients close to that required, vis. about 0.1 w/cm C . A coolant bed about 20'' long would be required and an annulus of about 2'' radial width round the specimen was considered to be practicable.

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

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  17. Numerical modelling 2 D and 3 D of circulating fluidized bed: application to the realization of regime diagrams; Modelisation numerique 2D et 3D de lit fluidise circulant: application a la realisation du diagramme des regimes

    Energy Technology Data Exchange (ETDEWEB)

    Begis, J.; Balzer, G.

    1997-02-01

    The numerical modelling of internal CFB boilers flows faced with complex phenomenons due to the flows un-stationariness, the heterogeneousness of the particle size distribution, and interactions between the two phases and the walls. Our study consisted in applying numerical models to the experimental configuration of cold circulating fluidized bed studied at the Cerchar. Special attention was given to the analysis of particles - wall interactions models, stemming from Jenkins (1992) and Louge`s (1994) theories, as well as the influence of the particles on fluid turbulence. In order to realize numerical simulations, we have used Eulerian two-phases flow codes developed at NHL medolif(2D), ESTET-ASTRID(3D). From different tests we have deducted that the most appropriate model for the realization of CFB`s prediction is the model taking in account the influence of particles on fluid turbulence. Then, to evaluate the validity limits of this model, we have built the regime diagram, and we have compared it with the experimental diagram. We have concluded that the simulation allows to describe the different CFB`s working regimes, and especially transitions. We have also noticed the importance of the choice of the mean diameter of the simulated particles. In this way, making a correction of the simulated particles` diameter in comparison with Sauter mean particle diameter, we obtained numerical results in good agreement with experimental data. (authors) 13 refs.

  18. Study of the behaviour of gaseous pollutants during the incineration of municipal solid waste in a circulating fluidized bed; Etude du devenir des polluants gazeux lors de l`incineration d`ordures menageres en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Desroches-Ducarne, E

    1997-09-30

    The Circulating Fluidized Bed (CFB) combustor seems to be a promising tool, being able to burn a variety of fuels whilst maintaining low emissions levels. The present work describes an experimental and theoretical investigation into the formation and destruction of acid gases (HCl and SO{sub 2}) and nitrogen oxides (NO and N{sub 2}O) during Municipal Solid Waste incineration. Experiments were conducted on six different fuels (namely MSW, mixtures of wood, paper, plastics, polyethylene...). The effect of five parameters (temperature, excess air, air staging, calcium addition and moisture) on the emissions levels was investigated. A statistical study on the experimental data allowed us to quantify the impact of the operating conditions and the influence of the fuel characteristics. A mathematical model has been developed which includes the main physical and chemical steps of combustion in CFB and which predicts the pollutant emissions under various operating conditions. A parametric study of the influence of operating conditions on emissions showed that in most cases the trends predicted by the model are in agreement with the experimental observations. (author) 175 refs.

  19. Experience gained in bench scale and pilot scale fluidised bed processing

    CSIR Research Space (South Africa)

    Hadley, TD

    2005-01-01

    Full Text Available of titanium dioxide. Expertise in the design and commissioning of industrial-scale plants has led to the supply (through licensees) of a biomass sludge incinerator/boiler generating 26t/h steam, a 20 MW high-sulphur pitch incinerator and a 12 MW fluidised bed...

  20. Granular dynamics simulation of segregation phenomena in bubbling gas-fluidised beds

    NARCIS (Netherlands)

    Hoomans, B.P.B.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2000-01-01

    A hard-sphere discrete particle model of a gas-fluidised bed was used in order to simulate segregation phenomena in systems consisting of particles of different sizes. In the model, the gas-phase hydrodynamics is described by the spatially averaged Navier¿Stokes equations for two-phase flow. For

  1. Heat transfer in a membrane assisted fluidised bed with immersed horizontal tubes

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; Volkers, S.; van Sint Annaland, M.; Kuipers, J.A.M.

    2004-01-01

    The effect of gas permeation through horizontally immersed membrane tubes on the heat transfer characteristics in a membrane assisted fluidised bed was investigated experimentally. Local time-averaged heat transfer coefficients from copper tubes arranged in a staggered formation with the membrane

  2. 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.

  3. Performance of entrained flow and fluidised bed biomass gasifiers on different scales

    International Nuclear Information System (INIS)

    Tremel, Alexander; Becherer, Dominik; Fendt, Sebastian; Gaderer, Matthias; Spliethoff, Hartmut

    2013-01-01

    Highlights: ► Gasification of biomass in fluidised bed and entrained flow reactors is modelled. ► The systems are evaluated for a thermal input from 10 MW to 500 MW. ► Special attention is given to the preconditioning methods for biomass. ► Fluidised bed and entrained flow gasifiers are compared in terms of efficiency and costs. - Abstract: This biomass gasification process study compares the energetic and economic efficiencies of a dual fluidised bed and an oxygen-blown entrained flow gasifier from 10 MW th to 500 MW th . While fluidised bed gasification became the most applied technology for biomass in small and medium scale facilities, entrained flow gasification technology is still used exclusively for industrial scale coal gasification. Therefore, it is analysed whether and for which capacity the entrained flow technology is an energetically and economically efficient option for the thermo-chemical conversion of biomass. Special attention is given to the pre-conditioning methods for biomass to enable the application in an entrained flow gasifier. Process chains are selected for the two gasifier types and subsequently transformed to simulation models. The simulation results show that the performance of both gasifier types is similar for the production of a pressurised product gas (2.5 MPa). The cold gas efficiency of the fluidised bed is 76–79% and about 0.5–2 percentage points higher than for the entrained flow reactor. The net efficiencies of both technologies are similar and between 64% and 71% depending on scale. The auxiliary power consumption of the entrained flow reactor is caused mainly by the air separation unit, the oxygen compression, and the fuel pulverisation, whereas the fluidised bed requires additional power mainly for gas compression. The costs for the product gas are determined as between €4.2 cent/kWh (500 MW th ) and €7.4 cent/kWh (10 MW th ) in the economic analysis of both technologies. The study indicates that the

  4. Kinetic evaluation of an anaerobic fluidised-bed reactor treating slaughterhouse wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Borja, R. [Consejo Superior de Investigaciones Cientificas, Seville (Spain). Inst. de la Grasa; Banks, C.J.; Zhengjian Wang [Manchester Univ. (United Kingdom). Inst. of Science and Technology

    1995-09-01

    An anaerobic fluidised-bed reactor for purification of slaughterhouse wastewater was modelled as a continuous-flow, completely-mixed homogeneous microbial system, with the feed COD as the limiting-substrate concentration. The average microbial residence time in the reactor was defined in terms of conventional sludge-retention-time. The experimental data obtained indicated that the Michaelis-Menten expression was applicable to a description of substrate utilisation (i.e. COD removal) in the anaerobic fluidised-bed system. The maximum substrate utilisation rate, k, and the Michaelis constant, K{sub s}, were determined to be 1.2/day and 0.039 g/l. The observed biomass yield in the reactor decreased with increasing sludge-retention-time. The specific methane production rate observed was a linear function of the specific substrate-utilisation rate. (Author)

  5. Gasification of Biomass with CO2 and H2O Mixtures in a Catalytic Fluidised Bed.

    Czech Academy of Sciences Publication Activity Database

    Jeremiáš, Michal; Pohořelý, Michael; Svoboda, Karel; Manovic, V.; Anthony, E.J.; Skoblia, S.; Beňo, Z.; Šyc, Michal

    2017-01-01

    Roč. 210, DEC 15 (2017), s. 605-610 ISSN 0016-2361 R&D Projects: GA ČR GC14-09692J Grant - others:NSC(TW) 103-2923-E-042A-001-MY3 Institutional support: RVO:67985858 Keywords : fluidised bed * gasification * catalyst Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use OBOR OECD: Energy and fuels Impact factor: 4.601, year: 2016

  6. Fluidisation and dispersion behaviour of small high density pellicular expanded bed adsorbents

    DEFF Research Database (Denmark)

    Theodossiou, Irini; Elsner, H.D.; Thomas, Owen R. T.

    2002-01-01

    correlation for characterisation of expanded bed systems is questioned. Residence time distribution studies using acetone tracers, demonstrated that in comparison to existing commercial supports, the small pellicular prototype materials generally possessed far superior hydrodynamic properties, which augurs......, fluidisation behaviour was poorly predicted from the Richardson-Zaki correlation, with experimentally determined values of the expansion index being considerably higher than the theoretical values. The reasons for these discrepancies are discussed in detail and the validity of applying this widely used...

  7. Gasification of Biomass with CO2 and H2O Mixtures in a Catalytic Fluidised Bed.

    Czech Academy of Sciences Publication Activity Database

    Jeremiáš, Michal; Pohořelý, Michael; Svoboda, Karel; Manovic, V.; Anthony, E.J.; Skoblia, S.; Beňo, Z.; Šyc, Michal

    2017-01-01

    Roč. 210, DEC 15 (2017), s. 605-610 ISSN 0016-2361 R&D Projects: GA ČR GC14-09692J Grant - others:NSC(TW) 103-2923-E-042A-001-MY3 Institutional support: RVO:67985858 Keywords : fluidised bed * gasification * catalyst Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use OBOR OECD: Energy and fuel s Impact factor: 4.601, year: 2016

  8. Model of fragmentation of limestone particles during thermal shock and calcination in fluidised beds

    Energy Technology Data Exchange (ETDEWEB)

    Saastamoinen, J.; Pikkarainen, T.; Tourunen, A.; Rasanen, M.; Jantti, T. [VTT Technical Research Center, Jyvaskyla (Finland)

    2008-11-15

    Fragmentation of limestone due to thermal shock and calcination in a fluidised bed was studied through experiments and modelling. The time for heating was estimated by model calculations and the time for calcination by measurements. Fragmentation due to thermal shock was carried out by experiments in a CO{sub 2} atmosphere in order to prevent the effect of calcination. It was found to be much less than fragmentation due to calcination. Average particle sizes before and after fragmentation are presented for several types of limestone. The effects of particle size and gas composition on the primary fragmentation were studied through experiments. Increasing the fluidisation velocity increased the tendency to fragment. The evolution of the particle size distribution (PSD) of limestone particles due to thermal shock and during calcination (or simultaneous calcination and sulphation) were calculated using a population balance model. Fragmentation due to thermal shock is treated as an instantaneous process. The fragmentation frequency during calcination is presented as exponentially decaying over time. In addition to the final PSD, this model also predicts the PSD during the calcination process. The fragmentation was practically found to end after 10 min. Furthermore. a population balance method to calculate the particle size distribution and amount of limestone in fluidised beds in dynamic and steady state, when feeding history is known, is presented.

  9. Local total and radiative heat-transfer coefficients during the heat treatment of a workpiece in a fluidised bed

    International Nuclear Information System (INIS)

    Gao, W.M.; Kong, L.X.; Hodgson, P.D.

    2006-01-01

    The heat-transfer coefficients around a workpiece immersed in an electrically heated heat treatment fluidised bed were studied. A suspension probe designed to simulate a workpiece of complex geometry was developed to measure local total and radiative heat-transfer coefficients at a high bed temperature. The probe consisted of an energy-storage region separated by insulation from the fluidised bed, except for the measuring surface, and a multi-thermocouple measurement system. Experiments in the fluidised bed were performed for a fluidising medium of 120-mesh alumina, a wide temperature range of 110-1050 deg. C and a fluidising number range of 1.18-4.24. It was found that the workpiece surface temperature has a more significant effect on heat transfer than the bed temperature. The total heat-transfer coefficient at the upper surface of the workpiece sharply decreased at the start of heating, and then steadily increased as heating progressed, while a sharp decrease became a rapid increase and then a slow increase for the radiative heat-transfer coefficient. A great difference in the heat-transfer coefficients around the workpiece was observed

  10. Dynamical and technological consequences of multiple isolas of steady states in a catalytic fluidised-bed reactor

    Directory of Open Access Journals (Sweden)

    Bizon Katarzyna

    2017-09-01

    Full Text Available Steady-state characteristics of a catalytic fluidised bed reactor and its dynamical consequences are analyzed. The occurrence of an untypical steady-state structure manifesting in a form of multiple isolas is described. A two-phase bubbling bed model is used for a quantitative description of the bed of catalyst. The influence of heat exchange intensity and a fluidisation ratio onto the generation of isolated solution branches is presented for two kinetic schemes. Dynamical consequences of the coexistence of such untypical branches of steady states are presented. The impact of linear growth of the fluidisation ratio and step change of the cooling medium temperature onto the desired product yield is analyzed. The results presented in this study confirm that the identification of a region of the occurrence of multiple isolas is important due to their strong impact both on the process start-up and its control.

  11. Validation of the flux number as scaling parameter for top-spray fluidised bed systems

    DEFF Research Database (Denmark)

    Hede, Peter Dybdahl; Bach, P.; Jensen, Anker Degn

    2008-01-01

    2SO4 using Dextrin as binder in three top-spray fluidised bed scales, i.e. a small-scale (type: GEA Aeromatic-Fielder Strea-1), medium-scale (type: Niro MP-1) and large-scale (type: GEA MP-2/3). Following the parameter guidelines adapted from the original patent description, the flux number....... Coating conditions with flux number values of 4.5 and 4.7 were however successful in terms of agglomeration tendency and match of particle size fractions, but indicated in addition a strong influence of nozzle pressure. The present paper suggests even narrower boundaries for the flux number compared...

  12. A multi-biofuel, fluidised-bed district heating plant in Sweden

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    At the end of 1984, the city of Haessleholm in Sweden started up a 65 MW district heating plant which included a 14 MW solid fuel plant. The plant included a specially-designed fluidised-bed boiler, capable of burning all grades of solid fuel, including organic fuel of such low grade that no other boilers around Haessleholm could use it. By 1992, the district heating system served some 250 detached houses and 6,000 flats as well as several schools and industrial premises. The biofuel boiler provides almost 60% of the energy required. (UK)

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

    CSIR Research Space (South Africa)

    Engelbrecht, AS

    2011-11-01

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

  14. Gasification of biomass and coal in a pressurised fluidised bed gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Andries, J; Jong, W de; Hein, K R.G. [Technische Univ. Delft (Netherlands)

    1998-09-01

    During a 3 year (1996-1998) multinational JOULE project, partly funded by the EU, experimental and theoretical research is being done on co-gasification of biomass (pelletised straw and Miscanthus) and coal in a pressurised fluidised bed reactor. The influence of feedstock and operating conditions on gasification characteristics has been studied using a 1.5 MW{sub th} gasifier, which has been operated at a pressure of 5 bar and temperatures up to 900 C. The project and the test rig are described and results obtained in the first part of the project are presented and analysed. (orig.)

  15. Gas-particle interactions in dense gas-fluidised beds

    NARCIS (Netherlands)

    Li, J.; Kuipers, J.A.M.

    2003-01-01

    The occurrence of heterogeneous flow structures in gas-particle flows seriously affects gas¿solid contacting and transport processes in dense gas-fluidized beds. A computational study, using a discrete particle method based on Molecular Dynamics techniques, has been carried out to explore the

  16. Energy recovery from sewage sludge by means of fluidised bed gasification

    International Nuclear Information System (INIS)

    Gross, Bodo; Eder, Christian; Grziwa, Peter; Horst, Juri; Kimmerle, Klaus

    2008-01-01

    Because of its potential harmful impact on the environment, disposal of sewage sludge is becoming a major problem all over the world. Today the available disposal measures are at the crossroads. One alternative would be to continue its usage as fertiliser or to abandon it. Due to the discussions about soil contamination caused by sewage sludge, some countries have already prohibited its application in agriculture. In these countries, thermal treatment is now presenting the most common alternative. This report describes two suitable methods to directly convert sewage sludge into useful energy on-site at the wastewater treatment plant. Both processes consist mainly of four devices: dewatering and drying of the sewage sludge, gasification by means of fluidised bed technology (followed by a gas cleaning step) and production of useful energy via CHP units as the final step. The process described first (ETVS-Process) is using a high pressure technique for the initial dewatering and a fluidised bed technology utilising waste heat from the overall process for drying. In the second process (NTVS-Process) in addition to the waste heat, solar radiation is utilised. The subsequent measures - gasification, gas cleaning and electric and thermal power generation - are identical in both processes. The ETVS-Process and the NTVS-Process are self-sustaining in terms of energy use; actually a surplus of heat and electricity is generated in both processes

  17. Recommendations for conversions of grate fired boilers to fluidising beds; Anvisningar foer konvertering av rosterpannor till fluidiserad baeddteknik

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Lars; Ingman, Rolf [AaF Energikonsult AB, Stockholm (Sweden)

    2001-03-01

    This report gives advice and recommendations for retrofitting of grate fired boilers to fluidising beds. Nine plants have been visited and experiences from these conversion projects have been gathered and analysed. Among the important points planning, fuel specification, heat balance calculations and clarifying of delivery limits can be mentioned. It is also important not to underestimate the need for education of the operational staff.

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

    Czech Academy of Sciences Publication Activity Database

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

    2017-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2017-01-01

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

  20. On suitability of novel fluidised bed technique for separation of metallic powders during commercial powder metallurgical processing

    NARCIS (Netherlands)

    Ritherdon, J; Dechsiri, C; Jones, AR; Hoffmann, AC; Wright, IG

    Experiments have been performed to test the efficiency with which a novel fluidised bed technique could separate different metallic powders in terms of size and density. The overall aim was to assess the potential of this technique for the commercial separation of defective powder fractions from

  1. Application of process tomography in gas-solid fluidised beds in different scales and structures

    Science.gov (United States)

    Wang, H. G.; Che, H. Q.; Ye, J. M.; Tu, Q. Y.; Wu, Z. P.; Yang, W. Q.; Ocone, R.

    2018-04-01

    Gas-solid fluidised beds are commonly used in particle-related processes, e.g. for coal combustion and gasification in the power industry, and the coating and granulation process in the pharmaceutical industry. Because the operation efficiency depends on the gas-solid flow characteristics, it is necessary to investigate the flow behaviour. This paper is about the application of process tomography, including electrical capacitance tomography (ECT) and microwave tomography (MWT), in multi-scale gas-solid fluidisation processes in the pharmaceutical and power industries. This is the first time that both ECT and MWT have been applied for this purpose in multi-scale and complex structure. To evaluate the sensor design and image reconstruction and to investigate the effects of sensor structure and dimension on the image quality, a normalised sensitivity coefficient is introduced. In the meantime, computational fluid dynamic (CFD) analysis based on a computational particle fluid dynamic (CPFD) model and a two-phase fluid model (TFM) is used. Part of the CPFD-TFM simulation results are compared and validated by experimental results from ECT and/or MWT. By both simulation and experiment, the complex flow hydrodynamic behaviour in different scales is analysed. Time-series capacitance data are analysed both in time and frequency domains to reveal the flow characteristics.

  2. Potential of synthesis gas production from rubber wood chip gasification in a bubbling fluidised bed gasifier

    International Nuclear Information System (INIS)

    Kaewluan, Sommas; Pipatmanomai, Suneerat

    2011-01-01

    Experiments of rubber wood chip gasification were carried out in a 100-kW th bubbling fluidised bed gasifier to investigate the effect of air to fuel ratio (represented as equivalence ratio - ER) on the yield and properties of synthesis gas. For all experiments, the flow rate of ambient air was fixed, while the feed rate of rubber wood chip was adjusted to vary ER in the range of 0.32-0.43. Increasing ER continuously raised the bed temperature, which resulted in higher synthesis gas yield and lower yield of ash and tar. However, higher ER generally gave synthesis gas of lower heating value, partly due to the dilution of N 2 . Considering the energy efficiency of the process, the optimum operation was achieved at ER = 0.38, which yielded 2.33 Nm 3 of synthesis gas per kg of dry biomass at the heating value of 4.94 MJ/Nm 3 . The calculated carbon conversion efficiency and gasification efficiency were 97.3% and 80.2%, respectively. The mass and energy balance of the gasification process showed that the mass and energy distribution was significantly affected by ER and that the energy losses accounted for ∼25% of the total output energy. The economical assessment of synthesis gas utilisation for heat and electricity production based on a 1-MW th bubbling fluidised bed gasifier and the operational data resulting from the rubber wood chip gasification experiments in this study clearly demonstrated the attractiveness of replacing heavy fuel oil and natural gas by the synthesis gas for heat applications in terms of 70% and 50% annual saving of fuel cost, respectively. However, the case of electricity production does not seem a preferable option due to its current technical and non-technical barriers.

  3. A new process control strategy for aqueous film coating of pellets in fluidised bed

    DEFF Research Database (Denmark)

    Larsen, C.C.; Sonnergaard, Jørn; Bertelsen, Pernille Scholdan

    2003-01-01

    The parameters with effect on maximum spray rate and maximum relative outlet air humidity when coating pellets in a fluidised bed were investigated. The tested variables include type of water based modified release film coating (Eudragit® NE 30D, Eudragit® RS 30D, Aquacoat ECD®) coating principle...... (top spray, bottom spray), inlet air humidity and type of pellets (sugar spheres, microcrystalline cellulose pellets). The maximum spray rate was not influenced by the coating principles. The highest spray rate was obtained for the film polymer with the lowest tackiness which is assumed...... to be the controlling factor. The type of pellets affected the maximum spray rate. A thermodynamic model for the coating process is employed throughout the process and not just during steady state. The thermodynamic model is incorporated into a new process control strategy. The process control strategy is based on in...

  4. 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.)

  5. Comparative simulation of a fluidised bed reformer using industrial process simulators

    Science.gov (United States)

    Bashiri, Hamed; Sotudeh-Gharebagh, Rahmat; Sarvar-Amini, Amin; Haghtalab, Ali; Mostoufi, Navid

    2016-08-01

    A simulation model is developed by commercial simulators in order to predict the performance of a fluidised bed reformer. As many physical and chemical phenomena take place in the reformer, two sub-models (hydrodynamic and reaction sub-models) are needed. The hydrodynamic sub-model is based on the dynamic two-phase model and the reaction sub-model is derived from the literature. In the overall model, the bed is divided into several sections. In each section, the flow of the gas is considered as plug flow through the bubble phase and perfectly mixed through the emulsion phase. Experimental data from the literature were used to validate the model. Close agreement was found between the model of both ASPEN Plus (ASPEN PLUS 2004 ©) and HYSYS (ASPEN HYSYS 2004 ©) and the experimental data using various sectioning of the reactor ranged from one to four. The experimental conversion lies between one and four sections as expected. The model proposed in this work can be used as a framework in developing the complicated models for non-ideal reactors inside of the process simulators.

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

    Energy Technology Data Exchange (ETDEWEB)

    Vainikka, P.

    2011-12-15

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

  7. Reactive Gas Solids Flow in Circulating Fluidised Beds

    DEFF Research Database (Denmark)

    Hjertager, Bjørn Helge; Solberg, Tron; Hansen, Kim Granly

    2005-01-01

    Progress in modelling and simulation of flow processes in gas/particle systems carried out at the authors? research group are presented. Emphasis is given to computational fluid dynamics (CFD) models that use the multi-dimensional multi fluid techniques. Turbulence modelling strategies for gas...

  8. Measurements of dioxin emissions during co-firing in a fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    I. Gulyurtlu; A.T. Crujeira; P. Abelha; I. Cabrita [INETI, Lisbon (Portugal). Departamento de Engenharia Energetica e Controle Ambiental

    2007-09-15

    The emissions of dioxins could be considerable when fuels with high chlorine content are used, particularly in fluidised beds due to constraints to use temperatures in the range 800-900{sup o}C for other considerations. However, mixing of fuels with different characteristics may lead to a reduction in dioxin emissions. Studies are currently being undertaken at the above-mentioned department in mixing fuels of varying chlorine and sulphur contents to monitor the emissions of dioxins both in the gas and solid phases. Furthermore, the influence of certain elements like Cu in the ash in the emissions of dioxins is also studied to verify the catalytic effect. The INETI pilot-scale test facility is used for the combustion work. Two different coals, namely Colombian and Polish, are used as the base fuel. The supplementary fuels for co-firing include MBM and straw pellets. The combustion temperature is maintained at about 800-830{sup o}C range without any limestone addition. The residence time of over 2 s is respected. Results obtained by far suggest that the presence of sulphur in both fuels have a very strong effect on the eventual emissions of dioxins and the synergy regarding to reduce the dioxins below the levels permitted is possible by mixing fuels based on their characteristics. The paper reports the results obtained and evaluates the effect of fuel nature and operating conditions on the emissions of dioxins. 34 refs., 8 figs., 12 tabs.

  9. Nutrients removal in hybrid fluidised bed bioreactors operated with aeration cycles.

    Science.gov (United States)

    Martin, Martin; Enríquez, L López; Fernández-Polanco, M; Villaverde, S; Garcia-Encina, P A

    2007-01-01

    Abstract Two hybrid fluidised bed reactors filled with sepiolite and granular activated carbon (GAC) were operated with short cycled aeration for removing organic matter, total nitrogen and phosphorous, respectively. Both reactors were continuously operated with synthetic and/or industrial wastewater containing 350-500 mg COD/L, 110-130 mg NKT/L, 90-100 mg NH3-N/L and 12-15 mg P/L for 8 months. The reactor filled with sepiolite, treating only synthetic wastewater, removed COD, ammonia, total nitrogen and phosphorous up to 88, 91, 55 and 80% with a hydraulic retention time (HRT) of 10 h, respectively. These efficiencies correspond to removal rates of 0.95 kgCODm(-3)d(-1) and 0.16 kg total N m(-3)d(-1). The reactor filled with GAC was operated for 4 months with synthetic wastewater and 4 months with industrial wastewater, removing 98% of COD, 96% of ammonia, and 66% of total nitrogen, with an HRT of 13.6 h. No significant phosphorous removing activity was observed in this reactor. Microbial communities growing with both reactors were followed using polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) techniques. The microbial fingerprints, i.e. DGGE profiles, indicated that biological communities in both reactors were stable along the operational period even when the operating conditions were changed.

  10. Co-gasification of meat and bone meal with coal in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    E. Cascarosa; L. Gasco; G. Gea; J.L. Sanchez; J. Arauzo [Universidad de Zaragoza (Spain). Thermochemical Processes Group

    2011-08-15

    After the Bovine Spongiform Encephalopathy illness appeared, the meat and bone meat (MBM) produced from animal residues became an important waste. In spite of being a possible fuel due to its heating value (around 21.4 MJ/kg), an important fraction of the meat and bone meal is being sent to landfills. The aim of this work is to evaluate the co-gasification of low percentages of meat and bone meal with coal in a fluidised bed reactor as a potential waste management alternative. The effect of the bed temperature (800-900{sup o}C), the equivalence ratio (0.25-0.35) and the percentage of MBM in the solid fed (0-1 wt.%) on the co-gasification product yields and properties is evaluated. The results show the addition of 1 wt.% of MBM in a coal gasification process increases the gas and the liquid yield and decreases the solid yield at 900{sup o}C and 0.35 of temperature and equivalence ratio operational conditions. At operational conditions of 900{sup o}C and equivalence ratio of 0.35, the specific yield to gas (y{sub gas}) increases from 3.18 m{sup 3}(STP)/kg to 4.47 m{sup 3}(STP)/kg. The gas energy yield decreased 24.1% and the lower heating value of the gas decreases from 3.36 MJ/m{sup 3}(STP) to 2.16 MJ/m{sup 3}(STP). The concentration of the main gas components (H{sub 2}, CO and CO{sub 2}) hardly varies with the addition of MBM, however the light hydrocarbon concentrations decrease and the H{sub 2}S concentration increases at the higher temperature (900{sup o}C). 32 refs., 9 figs., 7 tabs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-01

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

  12. Liquid transportation fuels via large-scale fluidised-bed gasification of lignocellulosic biomass

    Energy Technology Data Exchange (ETDEWEB)

    Hannula, I.; Kurkela, E.

    2013-04-15

    With the objective of gaining a better understanding of the system design trade-offs and economics that pertain to biomass-to-liquids processes, 20 individual BTL plant designs were evaluated based on their technical and economic performance. The investigation was focused on gasification-based processes that enable the conversion of biomass to methanol, dimethyl ether, Fischer-Tropsch liquids or synthetic gasoline at a large (300 MWth of biomass) scale. The biomass conversion technology was based on pressurised steam/O2-blown fluidised-bed gasification, followed by hot-gas filtration and catalytic conversion of hydrocarbons and tars. This technology has seen extensive development and demonstration activities in Finland during the recent years and newly generated experimental data has also been used in our simulation models. Our study included conceptual design issues, process descriptions, mass and energy balances and production cost estimates. Several studies exist that discuss the overall efficiency and economics of biomass conversion to transportation liquids, but very few studies have presented a detailed comparison between various syntheses using consistent process designs and uniform cost database. In addition, no studies exist that examine and compare BTL plant designs using the same front-end configuration as described in this work. Our analysis shows that it is possible to produce sustainable low-carbon fuels from lignocellulosic biomass with first-law efficiency in the range of 49.6-66.7% depending on the end-product and process conditions. Production cost estimates were calculated assuming Nth plant economics and without public investment support, CO2 credits or tax assumptions. They are 58-65 euro/MWh for methanol, 58-66 euro/MWh for DME, 64-75 euro/MWh for Fischer-Tropsch liquids and 68-78 euro/MWh for synthetic gasoline. (orig.)

  13. Thermal disposal of sewage sludges by fluidised bed combustion with low emissions of pollutants. Thermische Entsorgung kommunaler Klaerschlaemme durch schadstoffarme Verbrennung in der Wirbelschicht

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, B. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik); Lindau, S. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik); Busse, U. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik)

    1992-04-01

    The volume of sludge from the sewage treatment represents the largest problem in the waste management in Germany recently. The thermal treatment is inevitable for the solution of the problem. The fluidised bed combustion is suitable for a very good usability of sewage sludge. Experimental investigations carried out in a stationary fluidised bed in laboratory scale. The emissions of gaseous air pollutants are influenced by the properties of the sludge and the parameters of the process. The dependence of the formation and the reactions of the pollutants from various parameters are analysed and judged. (orig.)

  14. Results concerning a clean co-combustion technology of waste biomass with fossil fuel, in a pilot fluidised bed combustion facility

    Energy Technology Data Exchange (ETDEWEB)

    Ionel, Ioana; Trif-Tordai, Gavril; Ungureanu, Corneliu; Popescu, Francisc; Lontis, Nicolae [Politehnica Univ. Timisoara (Romania). Faculty for Mechanical Engineering

    2008-07-01

    The research focuses on a facility, the experimental results, interpretation and future plans concerning a new developed technology of using waste renewable energy by applying the cocombustion of waste biomass with coal, in a fluidised bed system. The experimental facility is working entirely in accordance to the allowed limits for the exhaust flue gas concentration, with special concern for typical pollutants. The experiments conclude that the technology is cleaner, has as main advantage the possibility to reduce both the SO{sub 2} and CO{sub 2} exhaust in comparison to standard fossil fuel combustion, under comparable circumstances. The combustion is occurring in a stable fluidised bed. (orig.)

  15. Gaseous emissions in pressurised fluidised-bed combustion. Analysis and summary of the pilot experiments; Kaasumaiset paeaestoet paineistetussa leijukerrospoltossa. Koetulosten kaesittely ja yhteenveto

    Energy Technology Data Exchange (ETDEWEB)

    Korpela, T.; Hippinen, I.; Konkola, M. [Helsinki Univ. of Technology, Espoo (Finland)

    1996-12-01

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

  16. Effect of organic loading rate on anaerobic treatment of slaughterhouse wastewater in a fluidised-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Borja, R. [Consejo Superior de Investigaciones Cientificas, Seville (Spain). Inst. de la Grasa; Banks, C.J.; Zhengjian Wang [Manchester Univ. (United Kingdom). Inst. of Science and Technology

    1995-09-01

    COD removal efficiencies in the range 75.0-98.9% were achieved in an aerobic fluidised-bed reactor treating slaughterhouse wastewater, when evaluated at organic loading rates (OLR) of between 2.9 and 54.0 g COD/l.d, hydraulic retention times (HRT) of between 0.5 and 8 h and feed COD concentrations of between 250 and 4500 mg/l. More than 94% of feed COD could be removed up to OLR of about 27 g COD/l.d. Up to 0.320 litres of methane were produced per gram of COD removed and this methane production rate was independent of the OLR applied in this investigation. Volatile fatty acid (VFA) concentration in the reactor increased sharply at an OLR of about 30 g COD/l.d and, therefore, sufficient alkalinity should be provided to prevent pH from dropping to an undesirable level. The anaerobic fluidised-bed system can be operated at a significantly higher liquid throughput than other previously reported systems while maintaining its excellent efficiency. (Author)

  17. Mathematical modelling of sewage sludge incineration in a bubbling fluidised bed with special consideration for thermally-thick fuel particles.

    Science.gov (United States)

    Yang, Yao Bin; Sharifi, Vida; Swithenbank, Jim

    2008-11-01

    Fluidised bed combustor (FBC) is one of the key technologies for sewage sludge incineration. In this paper, a mathematical model is developed for the simulation of a large-scale sewage sludge incineration plant. The model assumes the bed consisting of a fast-gas phase, an emulsion phase and a fuel particle phase with specific consideration for thermally-thick fuel particles. The model further improves over previous works by taking into account throughflow inside the bubbles as well as the floating and random movement of the fuel particles inside the bed. Validation against both previous lab-scale experiments and operational data of a large-scale industrial plant was made. Calculation results indicate that combustion split between the bed and the freeboard can range from 60/40 to 90/10 depending on the fuel particle distribution across the bed height under the specific conditions. The bed performance is heavily affected by the variation in sludge moisture level. The response time to variation in feeding rate is different for different parameters, from 6 min for outlet H2O, 10 min for O2, to 34 min for bed temperature.

  18. Discrete particle simulation of bubble and slug formation in a two-dimensional gas-fluidised bed: A hard-sphere approach.

    NARCIS (Netherlands)

    Hoomans, B.P.B.; Kuipers, J.A.M.; Briels, Willem J.; van Swaaij, Willibrordus Petrus Maria

    1996-01-01

    A discrete particle model of a gas-fluidised bed has been developed and in this the two-dimensional motion of the individual, spherical particles was directly calculated from the forces acting on them, accounting for the interaction between the particles and the interstitial gas phase. Our collision

  19. Making the most of South Africa’s low-quality coal: Converting high-ash coal to fuel gas using bubbling fluidised bed gasifiers

    CSIR Research Space (South Africa)

    Engelbrecht, AD

    2010-08-31

    Full Text Available for process heating or for power generation using the IGCC (Integrated Gasification Combined Cycle) process. A high-ash coal from the Waterberg coalfield was tested in a bubbling fluidised bed gasifier using various gasification agents and operating conditions...

  20. Co-combustion of coal and non-recyclable paper & plastic waste in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-07-01

    Co-combustion of waste with coal was carried out using a fluidised bed combustor with the aim of achieving a fuel mixture with little variations in its heating value and simultaneously reducing the accumulation of non-toxic waste material by upgrading them for energy purposes. Results obtained indicate that the feeding of waste materials could present serious problems which could render conditions for a stable combustion difficult to achieve. The waste was fed mixed with coal and there was some difference observed in results regarding the combustion efficiency and emissions. Part of the combustion of waste material, contrary to that of coal, was observed to take place in the freeboard where the temperature was as much as 150{degree}C above that of the bed. 6 refs., 8 figs., 8 tabs.

  1. Co-combustion of coal and non-recyclable paper and plastic waste in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-10-01

    Co-combustion of waste with coal was carried out using a fluidised bed combustor with the aim of achieving a fuel mixture with little variations in its heating value and simultaneously reducing the accumulation of non-toxic waste material by upgrading them for energy purposes. Results obtained indicate that the feeding of waste materials plays an important role to achieve conditions for a stable combustion. The form in which the fuel is fed to the combustor makes a significant contribution to achieve desirable combustion performance and differences were observed in results regarding the combustion efficiency and emissions when waste was fed densified or in a fluffy state when it was burned mixed with coal. Part of the combustion of waste material, contrary to that of coal, was observed to take place in the freeboard where the temperature was as much as 150{sup o}C above that of the bed. 15 refs., 8 figs., 8 tabs.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kassman, Haakan

    2012-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-06-01

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

  4. Nano particle fluidisation in model 2-D and 3-D beds using high speed X-ray imaging and microtomography

    International Nuclear Information System (INIS)

    Gundogdu, O.; Jenneson, P. M.; Tuzun, U.

    2007-01-01

    Nanoparticles and nanocomposites have become a major focus of interest in science and technology due to exceptional properties they provide. However, handling and processing of ultra-fine powders is very challenging because they are extremely cohesive. Fluidization is one of techniques available to process powders. It has become increasingly important to understand how these nanoparticles can be handled and processed to benefit from their favourable properties. A high spatial (down to 400 nm) and temporal resolution (down to 1 ms) X-ray imaging apparatus has been designed to study nanoparticles in fluidized beds under different gas flow velocities. The mean volume distribution of the nanoparticle agglomerates was determined with X-ray microtomography. The X-ray microtomography technique provides valuable in situ, non-destructive structural information on the morphological changes that take place during fluidisation of powder samples

  5. Nano particle fluidisation in model 2-D and 3-D beds using high speed X-ray imaging and microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Gundogdu, O. [University of Surrey, Chemical and Process Engineering, School of Engineering (United Kingdom)], E-mail: o.gundogdu@surrey.ac.uk; Jenneson, P. M. [University of Surrey, Department of Physics, School of Electronics and Physical Sciences (United Kingdom); Tuzun, U. [University of Surrey, Chemical and Process Engineering, School of Engineering (United Kingdom)

    2007-04-15

    Nanoparticles and nanocomposites have become a major focus of interest in science and technology due to exceptional properties they provide. However, handling and processing of ultra-fine powders is very challenging because they are extremely cohesive. Fluidization is one of techniques available to process powders. It has become increasingly important to understand how these nanoparticles can be handled and processed to benefit from their favourable properties. A high spatial (down to 400 nm) and temporal resolution (down to 1 ms) X-ray imaging apparatus has been designed to study nanoparticles in fluidized beds under different gas flow velocities. The mean volume distribution of the nanoparticle agglomerates was determined with X-ray microtomography. The X-ray microtomography technique provides valuable in situ, non-destructive structural information on the morphological changes that take place during fluidisation of powder samples.

  6. Axial concentration profiles and N{sub 2}O flue gas in a pilot scale bubbling fluidised bed coal combustor

    Energy Technology Data Exchange (ETDEWEB)

    Tarelho, L.A.C.; Matos, M.A.A.; Pereira, F.J.M.A. [Environment and Planning Department, University of Aveiro, 3810-193 Aveiro (Portugal)

    2005-05-15

    Atmospheric Bubbling Fluidised Bed Coal Combustion (ABFBCC) of a bituminous coal and anthracite with particle diameters in the range 500-4000 {mu}m was investigated in a pilot-plant facility (circular section with 0.25 m internal diameter and 3 m height). The experiments were conducted at steady-state conditions using three excess air levels (10%, 25% and 50%) and bed temperatures in the 750-900 {sup o}C range. Combustion air was staged, with primary air accounting for 100%, 80% and 60% of total combustion air. For both types of coal, virtually no N{sub 2}O was found in significant amounts inside the bed. However, just above the bed-freeboard interface, the N{sub 2}O concentration increased monotonically along the freeboard and towards the exit flue. The N{sub 2}O concentrations in the reactor ranged between 0-90 ppm during bituminous coal combustion and 0-30 ppm for anthracite. For both coals, the lowest values occurred at the higher bed temperature (900 {sup o}C) with low excess air (10%) and high air staging (60% primary air), whereas the highest occurred at the lower bed temperature (750 {sup o}C for bituminous, 825 {sup o}C for anthracite) with high excess air (50%) and single stage combustion. Most of the observed results could be qualitatively interpreted in terms of a set of homogeneous and heterogeneous reactions, where catalytic surfaces (such as char, sand and coal ash) can play an important role in the formation and destruction of N{sub 2}O and its precursors (such as HCN, NH{sub 3} and HCNO) by free radicals (O, H, OH) and reducing species (H{sub 2}, CO, HCs)

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

    Science.gov (United States)

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

    2017-04-01

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

  8. Testing of downstream catalysts for tar destruction with a guard bed in a fluidised bed biomass gasifier at pilot plant scale

    Energy Technology Data Exchange (ETDEWEB)

    Aznar, M.P.; Frances, E.; Campos, I.J.; Martin, J.A.; Gil, J. [Saragossa Univ. (Spain). Dept. of Chemistry and Environment Engineering; Corella, J. [Complutense Univ. of Madrid (Spain). Dept. of Chemical Engineering

    1996-12-31

    A new pilot plant for advanced gasification of biomass in a fast fluidised bed is now fully operative at University of Saragossa, Spain. It is a `3rd generation` pilot plant. It has been built up after having used two previous pilot plants for biomass gasification. The main characteristic of this pilot plant is that it has two catalytic reactors connected in series, downstream the biomass gasifier. Such reactors, of 4 cm i.d., are placed in a slip stream in a by-pass from the main gasifier exit gas. The gasification is made at atmospheric pressure, with flow rates of 3-50 kg/in, using steam + O{sub 2} mixtures as the gasifying agent. Several commercial Ni steam-reforming catalyst are being tested under a realistic raw gas composition. Tar eliminations or destructions higher than 99 % are easily achieved. (orig.) 2 refs.

  9. Testing of downstream catalysts for tar destruction with a guard bed in a fluidised bed biomass gasifier at pilot plant scale

    Energy Technology Data Exchange (ETDEWEB)

    Aznar, M P; Frances, E; Campos, I J; Martin, J A; Gil, J [Saragossa Univ. (Spain). Dept. of Chemistry and Environment Engineering; Corella, J [Complutense Univ. of Madrid (Spain). Dept. of Chemical Engineering

    1997-12-31

    A new pilot plant for advanced gasification of biomass in a fast fluidised bed is now fully operative at University of Saragossa, Spain. It is a `3rd generation` pilot plant. It has been built up after having used two previous pilot plants for biomass gasification. The main characteristic of this pilot plant is that it has two catalytic reactors connected in series, downstream the biomass gasifier. Such reactors, of 4 cm i.d., are placed in a slip stream in a by-pass from the main gasifier exit gas. The gasification is made at atmospheric pressure, with flow rates of 3-50 kg/in, using steam + O{sub 2} mixtures as the gasifying agent. Several commercial Ni steam-reforming catalyst are being tested under a realistic raw gas composition. Tar eliminations or destructions higher than 99 % are easily achieved. (orig.) 2 refs.

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

    Science.gov (United States)

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

    2007-08-17

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-08-17

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

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  13. Co-firing of biomass and other wastes in fluidised bed systems

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, I.; Lopes, H.; Boavida, D.; Abelha, P. [INETI/DEECA, Lisboa (Portugal); Werther, J.; Hartge, E.-U.; Wischnewski, R. [TU Hamburg-Harburg (Georgia); Leckner, B.; Amand, L.-E.; Davidsson, K. [Chalmers Univ. of Technology (Sweden); Salatino, P.; Chirone, R.; Scala, F.; Urciuolo, M. [Dipartimento di Ingegneria Chimica, Universita di Napoli Frederico II and Istituto di Ricerche sulla Combustione (Italy); Oliveira, J.F.; Lapa, N.

    2006-07-01

    A project on co-firing in large-scale power plants burning coal is currently funded by the European Commission. It is called COPOWER. The project involves 10 organisations from 6 countries. The project involves combustion studies over the full spectrum of equipment size, ranging from small laboratory-scale reactors and pilot plants, to investigate fundamentals and operating parameters, to proving trials on a commercial power plant in Duisburg. The power plant uses a circulating fluidized bed boiler. The results to be obtained are to be compared as function of scale-up. There are two different coals, 3 types of biomass and 2 kinds of waste materials are to be used for blending with coal for co-firing tests. The baseline values are obtained during a campaign of one month at the power station and the results are used for comparison with those to be obtained in other units of various sizes. Future tests will be implemented with the objective to achieve improvement on baseline values. The fuels to be used are already characterized. There are ongoing studies to determine reactivities of fuels and chars produced from the fuels. Reactivities are determined not only for individual fuels but also for blends to be used. Presently pilot-scale combustion tests are also undertaken to study the effect of blending coal with different types of biomass and waste materials. The potential for synergy to improve combustion is investigated. Simultaneously, studies to verify the availability of biomass and waste materials in Portugal, Turkey and Italy have been undertaken. Techno-economic barriers for the future use of biomass and other waste materials are identified. The potential of using these materials in coal fired power stations has been assessed. The conclusions will also be reported.

  14. Comparison of coal/solid recovered fuel (SRF) with coal/refuse derived fuel (RDF) in a fluidised bed reactor

    International Nuclear Information System (INIS)

    Wagland, S.T.; Kilgallon, P.; Coveney, R.; Garg, A.; Smith, R.; Longhurst, P.J.; Pollard, S.J.T.; Simms, N.

    2011-01-01

    An experimental study was undertaken to compare the differences between municipal solid waste (MSW) derived solid recovered fuel (SRF) (complying with CEN standards) and refuse derived fuel (RDF). Both fuels were co-combusted with coal in a 50 kW fluidised bed combustor and the metal emissions were compared. Synthetic SRF was prepared in the laboratory by grinding major constituents of MSW such as paper, plastic, textile and wood. RDF was obtained from a local mechanical treatment plant. Heavy metal emissions in flue gas and ash samples from the (coal + 10% SRF) fuel mixture were found to be within the acceptable range and were generally lower than that obtained for coal + 10% RDF fuel mixture. The relative distribution of heavy metals in ash components and the flue gas stream shows the presence of a large fraction (up to 98%) of most of the metals in the ash (except Hg and As). Thermo-gravimetric (TG) analysis of SRF constituents was performed to understand the behaviour of fuel mixtures in the absence and presence of air. The results obtained from the experimental study will enhance the confidence of fuel users towards using MSW-derived SRF as an alternative fuel.

  15. Effects of droplet size and type of binder on the agglomerate growth mechanisms by melt agglomeration in a fluidised bed.

    Science.gov (United States)

    Seo, Anette; Holm, Per; Schaefer, Torben

    2002-08-01

    This study was performed in order to evaluate the effects of binder droplet size and type of binder on the agglomerate growth mechanisms by melt agglomeration in a fluidised bed granulator. Lactose monohydrate was agglomerated with melted polyethylene glycol (PEG) 3000 or Gelucire 50/13 (esters of polyethylene glycol and glycerol), which was atomised at different nozzle air flow rates giving rise to median droplet sizes of 40, 60, and 80 microm. Different product temperatures were investigated, below the melting range, in the middle of the melting range, and above the melting range for each binder. The agglomerates were found to be formed by initial nucleation of lactose particles immersed in the melted binder droplets. Agglomerate growth occurred by coalescence between nuclei followed by coalescence between agglomerates. Complex effects of binder droplet size and type of binder were seen at low product temperatures. Low product temperatures resulted in smaller agglomerate sizes, because the agglomerate growth was counteracted by very high binder viscosity or solidification of the binder. At higher product temperatures, neither the binder droplet size nor the type of binder had a clear effect on the final agglomerate size.

  16. Fluidised bed combustion: a new route to power and heat from coal

    Energy Technology Data Exchange (ETDEWEB)

    Schilling, H D [Bergbau-Forschung G.m.b.H., Essen (Germany, F.R.)

    1978-02-01

    The functioning of fluidized-bed firings and their advantages with regard to SO/sub 2/ emissions are described. The principle of design of a fluidized-bed boiler and a gas/steam turbine power plant with fluidized-bed firing under pressure is outlined. The application and their economics in heat and power generation and marketing potential of fluidized-bed firings and their economics in heat and power generation is pointed out. The construction of waste-fired incinerators has already become possible, but there is still a lot of development work to be done until fluidized-bed firings can be used in central heatings, combined-cycle power plants, and large power plants.

  17. Wear oxidation of evaporator coils in fluidised bed captive power plants

    International Nuclear Information System (INIS)

    Ghosal, S.K.; De, P.K.

    2000-01-01

    Combustion of pulverised coal or gas to form steam in thermal power plants is a common practice. Corrosion of water-wall, superheater and reheater tubes is the typical problem faced in these power plants. Modification of process conditions, redesigning of equipment and selection of more corrosion resistant materials are few methods which have been tried to combat corrosion to a certain extent. Restricted heat transfer efficiency is another problem associated with these power plants. In order to bring upon improvements, fluidized bed combustors are being used in some advanced thermal power plants at present because of excellent combustion and heat transfer efficiencies. Even with low grade coals, higher combustion efficiency could be achieved in these combustors due to excellent gas/solid chemical reactivity at relatively low reaction temperatures. Further improvements in in-bed heat transfer and bed temperature uniformity have been possible with the use of sand in bed. However, erosion, corrosion and combined erosion/corrosion are some of the major modes of material degradation associated with these fluidized bed combustors using sand. Recently in a captive power unit using bubbling fluidized bed combustors containing sand, evaporator coils made of carbon steel were seen to be severely affected by erosion corrosion. The directional nature of metal removal from the studs, tube OD and ultimately the rupture of the thinned tube wall confirmed the above observation. Microstructural examinations showed loss of carbon at certain places including those near the leaked/punctured regions at the prevailing bed temperature of 850 deg C. This paper describes the detailed investigations carried out on wear oxidation phenomenon occurred in a captive thermal power plant using advanced bubbling fluidized bed combustors. (author)

  18. Particulate and PCDD/F emissions from coal co-firing with solid biofuels in a bubbling fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    H. Lopes; I. Gulyurtlu; P. Abelha; T. Crujeira; D. Salema; M. Freire; R. Pereira; I. Cabrita [INETI, Lisbon (Portugal). DEECA

    2009-12-15

    In the scope of the COPOWER project SES6-CT-2004 to investigate potential synergies of co-combustion of different biofuels with coal, a study of emissions of particulate matter and PCDD/F was carried out. The biofuels tested were meat and bone meal (MBM), sewage sludge biopellets (BP), straw pellets (SP), olive bagasse (OB) and wood pellets (WP). The tests performed include co-firing of 5%, 15% and 25% by weight of biofuels with coals of different origin. Both monocombustion and co-firing were carried out. Combustion tests were performed on a pilot fluidised bed, equipped with cyclones and air staging was used in order to achieve almost complete combustion of fuels with high volatile contents and to control gaseous emissions. Particulate matter emissions were isokinetically sampled in the stack and their particle size analysis was performed with a cascade impactor (Mark III). The results showed that most particles emitted were below 10 {mu}m (PM10) for all the tests, however, with the increasing share of biofuels and also during combustion of pure biofuels, especially olive bagasse, straw and MBM, very fine particles, below about 1 {mu}m were present. With the exception of sewage sludge, greater amounts of biofuels appeared to give rise to the decrease in particulate mean diameters and increase in PM percentages below 1 {mu}m. The formation of very fine particles could be related with the presence of aerosol forming elements such as K, Na (in the case of MBM) and Cl in biofuels, which even resulted in higher PM emissions when the ash content of fuels decreased. A correlation wasverified between the increase of PCDD/F with the decrease of PM mean diameter. This may be due to higher specific surface area and greater Cu concentration in the fly ashes. 33 refs., 11 figs., 4 tabs.

  19. Cofiring of difficult fuels: The effect of Ca-based sorbents on the gas chemistry in fluidised bed combustion; Kalsiumpohjaisten lisaeaineiden vaikutus leijukerrospolton kaasukemiaan vaikeiden polttoaineiden sekapoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Aeijaelae, M.; Partanen, J.; Fabritius, M.; Elo, T.; Virta, A.K. [Imatran Voima Oy, Vantaa (Finland)

    1997-10-01

    The objective of this project is to establish the effects of Ca-based sorbents on sulphur, halogen and alkaline chemistry in fluidised bed combustion of difficult fuels, and to find out any restrictions on the use of these sorbents. The aim is to acquire sufficient knowledge to ensure the operational reliability of power plants and to minimise the emissions and costs of flue gas cleaning. The results enable the owner to anticipate necessary changes associated with slagging, fouling and emission control in the existing power plants, when there are plans to increase the range of fuels used. (orig.)

  20. Fluidised bed technology – Applications and R&D in Southern Africa

    CSIR Research Space (South Africa)

    North, BC

    2007-06-28

    Full Text Available Bed area : 25 m2 Plant purpose : A 10 MW plant for the combustion of duff coal at greater than 98 % burnout to provide hot gases for drying slag. Subsequently also used for organic waste incineration. Project duration : 1988 to 1989 Current...

  1. Experience gained in pilot-scale and bench-scale fluidised beds processing

    CSIR Research Space (South Africa)

    Hadley, TD

    2006-02-01

    Full Text Available for clean coal technology thrust COMMISSIONED PLANTS Slagment Hot Gas Generator Client : Slagment Bed area : 25 m2 Plant purpose : A 10 MW plant for the combustion of duff coal at greater than 98% burnout to provide hot gases for the drying...

  2. Hydrodynamics of circulating and bubbling fluidized beds

    International Nuclear Information System (INIS)

    Gidaspow, D.P.; Tsuo, Y.P.; Ding, J.

    1991-01-01

    This paper reports that a review of modeling of the hydrodynamics of fluidization of bubbling beds showed that inviscid two-fluid models were able to predict a great deal of the behavior of bubbling beds because the dominant mechanism of energy dissipation is the drag between the particles and the fluid. The formation, the growth and the bursting of bubbles were predicted. Predicted wall-to-bed heat transfer coefficients and velocity profiles of jets agreed with measurements. Time average porosity distributions agreed with measurements done using gamma-ray densitometers without the use of any adjustable parameters. However, inviscid models could not correctly predict rates of erosion around tubes immersed into fluidized beds. To correctly model such behavior, granular stresses involving solids viscosity were added into the computer model. This viscosity arises due to random collision of particles. Several models fro this viscosity were investigated and the results compared to measurements of solids distributions in two-dimensional beds and to particle velocities reported in the literature. While in the case of bubbling beds the solids viscosity plays the role of a correction, modeling of a circulating fluidized bed (CFB) without a viscosity is not possible. Recent experimental data obtained at IIT and at IGT show that in CFB the solids viscous dissipation is responsible for as much as half of the pressure drop. From such measurement, solids viscosities were computed. These were used in the two fluid hydrodynamic model, to predict radial solids distributions and solids velocities which matched the experimental distributions. Most important, the model predicted cluster formation and transient internal circulation which is responsible for the favorable characteristics of CFBs, such as good wall-to-bed heat transfer. Video tape movies of computations compared favorably with high speed movies of the experiments

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

    Directory of Open Access Journals (Sweden)

    W. A. WAN AB KARIM GHANI

    2009-03-01

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

  4. Carbonation of Mg(OH){sub 2} in a pressurised fluidised bed for CO{sub 2} sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Fagerlund, J.

    2012-07-01

    To date, a number of methods to accelerate natural weathering or in other words increase the CO{sub 2} uptake rate of various minerals have been suggested; commonly this is known as mineral carbonation or CO{sub 2} mineralisation. A brief literature review of recently published articles in this field is presented, showing that the interest in mineral carbonation is increasing. However, it should be noted that mineral carbonation is only one option in a larger portfolio of various carbon dioxide capture and storage (CCS) alternatives. Unlike many other options, the CO{sub 2} mineralisation option considered in this thesis is largely founded on the possibility to utilise the exothermic nature of magnesium carbonation and based on this notion, it has been divided into three steps. The first two steps are energy demanding, while the third step is energy 'negative', and in theory, the source of the energy required in the first two steps. Unfortunately, however, the energy demanded by the first two steps, Mg extraction and Mg(OH){sub 2} production, is (currently) much higher than what could be generated by the subsequent Mg(OH){sub 2} carbonation step. Nevertheless, opportunities to reduce the energy intensity of the process in question are still being investigated, and while an energy-neutral carbonation process might be difficult to achieve, energy requirements can still be rendered industrially acceptable (and comparable to or even better than for other CCS methods). The main focus of this thesis lies with the third step, Mg(OH){sub 2} carbonation, which is performed using a pressurised fluidised bed (PFB). The elevated CO{sub 2} pressure conditions (typically approx 20 bar) allow for the carbonation reaction to take place at higher temperatures (typically approx 500 deg C) than otherwise due to thermodynamic constraints on carbonate stability. The increase in reaction rate as a function of temperature follows the Arrhenius equation of exponential increase

  5. Feasibility study - Lowered bed temperature in Fluidised Bed boilers for waste; Foerstudie - Saenkt baeddtemperatur i FB-pannor foer avfallsfoerbraenning

    Energy Technology Data Exchange (ETDEWEB)

    Niklasson, Fredrik

    2009-01-15

    Waste incineration generally serves two purposes; 1) dispose of waste and 2) generation of heat and power. In the process of power production from waste fuels, the steam temperatures in super heaters are generally limited by the severe fouling and corrosion that occurs at elevated material temperatures, caused by high concentrations of alkali metals and chloride in the flue gas and fly ash. The overall aim of a continuation of present project is to determine if a reduced temperature of the bed zone in a fluidized bed waste incinerator reduces the amount of alkali chlorides in the flue gas. If so, a reduced bed temperature might enable increased steam temperature in super heaters, or, at unchanged steam temperature, improve the lifespan of the super heaters. The results from the project are of interest for plant owners wishing to improve performance of existing plants. The results may also be used to modify the design of future plants by boiler manufacturers. The aim of present pre-study was to determine how far the bed temperature can be reduced in a waste fired fluidized bed boiler in Boraas while maintaining a stable operation with sufficient combustion temperature in the freeboard to fulfil the directives of waste incineration. A continuation of the project will be based on the results from present study. The work is based on experiments at the test boiler. During the present study, no other measurements were performed apart from some sampling of bed material and ashes at different modes of operation. The experiments show that it is possible to alter the air and recycled flue gas in such a manner that the bed temperature is reduced from about 870 deg C to 700 deg C at 100% load and normal fuel mixture, while fulfilling the directive of 850 deg C at 2 seconds. Within normal variations of the fuel properties, however, the bed temperature increases to somewhat above 700 deg C if the fuel turns dry, while it falls below 650 deg C when the fuel turns wet. With

  6. Dry formulations of the biocontrol agent Candida sake CPA-1 using fluidised bed drying to control the main postharvest diseases on fruits.

    Science.gov (United States)

    Carbó, Anna; Torres, Rosario; Usall, Josep; Fons, Estanislau; Teixidó, Neus

    2017-08-01

    The biocontrol agent Candida sake CPA-1 is effective against several diseases. Consequently, the optimisation of a dry formulation of C. sake to improve its shelf life and manipulability is essential for increasing its potential with respect to future commercial applications. The present study aimed to optimise the conditions for making a dry formulation of C. sake using a fluidised bed drying system and then to determine the shelf life of the optimised formulation and its efficacy against Penicillium expansum on apples. The optimal conditions for the drying process were found to be 40 °C for 45 min and the use of potato starch as the carrier significantly enhanced the viability. However, none of the protective compounds tested increased the viability of the dried cells. A temperature of 25 °C for 10 min in phosphate buffer was considered as the optimum condition to recover the dried formulations. The dried formulations should be stored at 4 °C and air-packaged; moreover, shelf life assays indicated good results after 12 months of storage. The formulated products maintained their biocontrol efficacy. A fluidised bed drying system is a suitable process for dehydrating C. sake cells; moreover, the C. sake formulation is easy to pack, store and transport, and is a cost-effective process. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  7. Pressurised fluidised-bed gasification experiments with biomass, peat and coal at VTT in 1991-1994. Gasification of Danish wheat, straw and coal

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E; Laatikainen-Luntama, J; Staahlberg, P; Moilanen, A [VTT Energy, Espoo (Finland). Energy Production Technologies

    1997-12-31

    Fluidised-bed air gasification of three different Danish straw feedstocks and Colombian bituminous coal was studied in the PDU-scale test facilities of VTT. The test programme was divided into two different modes of operation. First, the usability of straw as the only feedstock was investigated by operating the gasifier at relatively low temperature normally used in biomass gasifiers. In this operation mode the main aim was to find out the limits for gasification temperatures, set by the sintering behaviour of the straw. Secondly, the use of straw as an additional feedstock in a fluidised-bed coal gasifier was examined by operating the gasifier at about 1 000 deg C with different ratings of straw and coal feeding. The gasifier was operated at 5 bar pressure and at 80 990 deg C. The product gas was cleaned by ceramic candle filters operated at 465-540 deg C. Concentrations of tars, nitrogen com- pounds, sulphur gases, vapour-phase alkali metals as well as chlorine were determined in different operating conditions. (12 refs.)

  8. Circulating fluidized bed boilers design and operations

    CERN Document Server

    Basu, Prabir

    1991-01-01

    This book provides practicing engineers and students with insight into the design and operation of circulating fluidized bed (CFB) boilers. Through a combination of theoretical concepts and practical experience, this book gives the reader a basic understanding of the many aspects of this subject.Important environmental considerations, including solid waste disposal and predicted emissions, are addressed individually in separate chapters. This book places an emphasis on combustion, hydrodynamics, heat transfer, and material issues, and illustrates these concepts with numerous examples of pres

  9. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    The objective of this DOE Cooperative Agreement is to conduct a cost-shared clean coal technology project to demonstrate the feasibility of circulating fluidized bed combustion technology and to evaluate economic, environmental, and operational benefits of CFB steam generators on a utility scale. At the conclusion of the Phase 2 program, testing related to satisfying these objectives was completed. Data analysis and reporting are scheduled for completion by October 1991. (VC)

  10. Hydrodynamic study of the turbulent fluidized beds; Etude hydrodynamique des lits fluidises turbulents

    Energy Technology Data Exchange (ETDEWEB)

    Taxil, I.

    1996-12-20

    Gas-solid turbulent fluidization has already been widely studied in the literature. However, its definition and specificities remain controversial and confused. Most of the studies focussed on the turbulent transition velocities are based on wall pressure drop fluctuations studies. In this work, we first characterize the turbulent regime with the classical study of pressure drop signals with standard deviation analysis, completed with a more specific frequency analysis and also by a stochastic analysis. Then, we evaluate bubble flow properties. Experimental results have been obtained in a 0.2 m I.D. fluidized bed expanding to 0.4 m I.D. in the freeboard in order to limit entrainment at high fluidization velocities. The so lid used was FCC catalyst. It was fluidized by air at ambient conditions. The superficial fluidization velocity ranged 0.2 to 2 m/s. Fast response transducers recorded pressure drop at the wall and bubble flow properties (bubble size, bubble velocity and bubble frequency) could be deduced from a light reflected signal at various bed locations with optical fibers. It has been shown the turbulent regime is delimited by two velocities: Uc (onset of turbulent regime) and Utr (onset of transport regime), which can be determined based on standard deviations, dominant frequencies and width of wave land of pressure signals. The stochastic analysis confirms that the signal enriches in frequencies in the turbulent regime. Bubble size and bubble velocity could be correlated to the main superficial gas velocity. The main change in bubble flow in the turbulent regime was shown to be the stagnation of the bubble frequency at its maximum value. It was also shown that the bubble flow properties in the turbulent regime imply a strong aeration of the emulsion phase. (authors) 76 refs.

  11. Bed system performance in helium circulation mode

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yean Jin; Jung, Kwang Jin; Ahn, Do Hee; Chung, Hong Suk [UST, Daejeon (Korea, Republic of); Kang, Hee Suk [KAERI, Daejeon (Korea, Republic of); Yun, Sei Hun [NFRI, Deajeon (Korea, Republic of)

    2016-05-15

    As a part of the International Thermonuclear Experimental Reactor (ITER) Project, We have conducted an experiment for storing hydrogen to depleted uranium and zirconium cobalt. The helium blanket effect has been observed in experiments using metal hydrides. The collapse of the hydrogen isotopes are accompanied by the decay heat and helium-3. Helium-3 dramatically reduces the hydrogen isotope storage capacity by surrounding the metal. This phenomenon is called a helium blanket effect. In addition the authors are working on the recovery and removal techniques of helium-3. In this paper, we discuss the equipment used to test the helium blanket effect and the results of a helium circulation experiment. The helium-3 produced surrounds the storage material surface and thus disturbs the reaction of the storage material and the hydrogen isotope. Even if the amount of helium-3 is small, the storage capacity of the SDS bed significantly drops. This phenomenon is the helium blanket effect. To resolve this phenomenon, a circulating loop was introduced. Using a circulating system, helium can be separated from the storage material. We made a helium loop that includes a ZrCo bed. Then using a metal bellows pump, we tested the helium circulation.

  12. CIRCULATING MOVING BED COMBUSTION PROOF OF CONCEPT

    Energy Technology Data Exchange (ETDEWEB)

    Jukkola, Glen

    2010-06-30

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

  13. Nucla circulating atmospheric fluidized bed demonstration project

    Energy Technology Data Exchange (ETDEWEB)

    Keith, Raymond E.

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute's decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  14. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Keith, Raymond E.; Heller, Thomas J.; Bush, Stuart A.

    1991-01-01

    This Annual Report on Colorado-Ute Electric Association's NUCLA Circulating Fluidized Bed (CFB) Demonstration Program covers the period from February 1987 through December 1988. The outline for presentation in this report includes a summary of unit operations along with individual sections covering progress in study plan areas that commenced during this reporting period. These include cold-mode shakedown and calibration, plant commercial performance statistics, unit start-up (cold), coal and limestone preparation and handling, ash handling system performance and operating experience, tubular air heater, baghouse operation and performance, materials monitoring, and reliability monitoring. During this reporting period, the coal-mode shakedown and calibration plan was completed. (VC)

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

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Gaston

    2011-07-15

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

  16. Single particle behaviour in circulating fluidized bed combustors

    DEFF Research Database (Denmark)

    Erik Weinell, Claus

    1994-01-01

    An investigation of single particle behaviour in a circulating fluidized bed combustor is described, relating to sulphur capture reactions by limestone under alternate oxidizing and reducing conditions present in a circulating fluidized bed combustor, and to the devolatilization and burn out...

  17. Wall heat flux influence on the thermodynamic optimisation of irreversibilities of a circulating fluidised bed combustor

    CSIR Research Space (South Africa)

    Baloyi, J

    2016-07-01

    Full Text Available . The irreversibilities generated were arrived at by computing the entropy generation rates due to the combustion and frictional pressure drop processes. For the combustor where the wall condition was changed from adiabatic to negative heat flux (that is heat leaving...

  18. Control of the Bed Temperature of a Circulating Fluidized Bed Boiler by using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    AYGUN, H.

    2012-05-01

    Full Text Available Circulating fluidized bed boilers are increasingly used in the power generation due to their higher combustion efficiency and lower pollutant emissions. Such boilers require an effective control of the bed temperature, because it influences the boiler combustion efficiency and the rate of harmful emissions. A Particle-Swarm-Optimization-Proportional-Integrative-Derivative (PSO-PID controller for the bed temperature of a circulating fluidized bed boiler is presented. In order to prove the capability of the proposed controller, its performances are compared at different boiler loads with those of a Fuzzy Logic (FL controller. The simulation results demonstrate some advantages of the proposed controller.

  19. Refractory experience in circulating fluidized bed combustors, Task 7

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, R.Q.

    1989-11-01

    This report describes the results of an investigation into the status of the design and selection of refractory materials for coal-fueled circulating fluidized-bed combustors. The survey concentrated on operating units in the United States manufactured by six different boiler vendors: Babcock and Wilcox, Combustion Engineering, Foster Wheeler, Keeler Dorr-Oliver, Pyropower, and Riley Stoker. Information was obtained from the boiler vendors, refractory suppliers and installers, and the owners/operators of over forty units. This work is in support of DOE's Clean Coal Technology program, which includes circulating fluidized-bed technology as one of the selected concepts being evaluated.

  20. Multi-stage circulating fluidized bed syngas cooling

    Science.gov (United States)

    Liu, Guohai; Vimalchand, Pannalal; Guan, Xiaofeng; Peng, WanWang

    2016-10-11

    A method and apparatus for cooling hot gas streams in the temperature range 800.degree. C. to 1600.degree. C. using multi-stage circulating fluid bed (CFB) coolers is disclosed. The invention relates to cooling the hot syngas from coal gasifiers in which the hot syngas entrains substances that foul, erode and corrode heat transfer surfaces upon contact in conventional coolers. The hot syngas is cooled by extracting and indirectly transferring heat to heat transfer surfaces with circulating inert solid particles in CFB syngas coolers. The CFB syngas coolers are staged to facilitate generation of steam at multiple conditions and hot boiler feed water that are necessary for power generation in an IGCC process. The multi-stage syngas cooler can include internally circulating fluid bed coolers, externally circulating fluid bed coolers and hybrid coolers that incorporate features of both internally and externally circulating fluid bed coolers. Higher process efficiencies can be realized as the invention can handle hot syngas from various types of gasifiers without the need for a less efficient precooling step.

  1. Investigation of coalescence kinetics of microcristalline cellulose in fluidised bed spray agglomeration: experimental studies and modelling approach

    Directory of Open Access Journals (Sweden)

    M. Peglow

    2005-06-01

    Full Text Available In this paper a model for fluidized bed spray agglomeration is presented. To describe the processes of heat and mass transfer, a physical based model is derived. The model takes evaporation process from the wetted particles as well as the effects of transfer phenomena between suspension gas and bypass gas into account. The change of particle size distribution during agglomeration, modeled by population balances, is linked to the heat and mass transfer model. A new technique is derived to extract agglomeration and nucleation rates from experimental data. Comparisons of experiments and simulations are presented.

  2. Single-particle behaviour in circulating fluidized beds

    DEFF Research Database (Denmark)

    Erik Weinell, Claus; Dam-Johansen, Kim; Johnsson, Jan Erik

    1997-01-01

    This paper describes an experimental investigation of single-particle behaviour in a cold pilot-scale model of a circulating fluidized bed combustor (CFBC). In the system, sand is recirculated by means of air. Pressure measurements along the riser are used to determine the suspension density...

  3. Investigation on catalytic gasification of high-ash coal with mixing-gas in a small-scale fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.; Zhang, J.; Lin, J. [Fuzhou University, Fuzhou (China)

    2005-10-15

    The experimental study on the Yangquan high-ash coal catalytic gasification with mixing gas by using solid alkali or waste liquid of viscose fiber as the catalyst in a small-scale fluidized bed with 28 mm i.d. was carried out. The loading saturation levels of two catalysts in Yangquan high-ash coal are about 6%. Under the gasification temperature ranging from 830 to 900{sup o}C and from 900 to 920{sup o}C, the apparent reaction order of Yangquan high-ash coal with respect to the unreacted carbon fraction approximates to 2.3 and 1/3 for the non-catalyst case, respectively. Also, the different values of apparent reaction order in the two temperature ranges are presented for the case with 3% solid alkali catalyst loaded. At the low temperature ranging from 830 to 860{sup o}C, the apparent reaction order of catalytic gasification is 1 since enough active carbon sites on the coal surface are formed during the catalytic gasification by solid alkali. But at the high temperature ranging from 860 to 920{sup o}C, the sodium carbonate produced by the reaction of solid alkali with carbon dioxide can be easily fused, transferred and re-distributed, which affects the gasification reaction rate, and the apparent reaction order of catalytic gasification is reduced to 1.3. 10 refs., 9 figs., 4 tab s.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

  5. Pulverized coal vs. circulating fluidized bed: An economic comparison

    International Nuclear Information System (INIS)

    Johns, R.F.

    1991-01-01

    As the power industry looks to the 1990s for expanded steam generation capacity, boiler owners will continue on their long-standing assignment to evaluate and select the best, lowest cost alternative to meet their energy needs. For coal-fired plants, this evaluation process includes pulverized coal-fired boilers (PC) and circulating fluidized bed boilers (CFB). The cost difference between these products is site specific and depends on several variables, including: Boiler size, pressure, and temperature; Operating variables, such as the cost for fuel, auxiliary power, SO 2 reagent, and ash disposal; Capital cost; and Financial variables, such as evaluation period and interest rate. This paper provides a technical and economic comparison between a pulverized coal-fired boiler and circulating fluidized bed boiler

  6. Combustion of Jordanian oil shale using circulating fluidized bed

    International Nuclear Information System (INIS)

    Hamdan, M.; Al-Azzam, S.

    1998-11-01

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

  7. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project. 1990 Annual report

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    The objective of this DOE Cooperative Agreement is to conduct a cost-shared clean coal technology project to demonstrate the feasibility of circulating fluidized bed combustion technology and to evaluate economic, environmental, and operational benefits of CFB steam generators on a utility scale. At the conclusion of the Phase 2 program, testing related to satisfying these objectives was completed. Data analysis and reporting are scheduled for completion by October 1991. (VC)

  8. Chemical looping reactor system design double loop circulating fluidized bed (DLCFB)

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    Chemical looping combustion (CLC) is continuously gaining more importance among the carbon capture and storage (CCS) technologies. It is an unmixed combustion process which takes place in two steps. An effective way to realize CLC is to use two interconnected fluidized beds and a metallic powder circulating among them, acting as oxygen carrier. The metallic powder oxidizes at high temperature in one of the two reactors, the air reactor (AR). It reacts in a highly exothermic reaction with the oxygen of the injected fluidising air. Afterwards the particles are sent to the other reactor where the fuel is injected, the fuel reactor (FR). There, they transport heat and oxygen necessary for the reaction with the injected fuel to take place. At high temperatures, the particle's oxygen reacts with the fuel producing Co2 and steam, and the particles are ready to start the loop again. The overall reaction, the sum of the enthalpy changes of the oxygen carrier oxidation and reduction reactions, is the same as for the conventional combustion. Two are the key features, which make CLC promising both for costs and capture efficiency. First, the high inherent irreversibility of the conventional combustion is avoided because the energy is utilized stepwise. Second, the Co2 is intrinsically separated within the process; so there is in principle no need either of extra carbon capture devices or of expensive air separation units to produce oxygen for oxy-combustion. A lot of effort is taking place worldwide on the development of new chemical looping oxygen carrier particles, reactor systems and processes. The current work is focused on the reactor system: a new design is presented, for the construction of an atmospheric 150kWth prototype working with gaseous fuel and possibly with inexpensive oxygen carriers derived from industrial by-products or natural minerals. It consists of two circulating fluidized beds capable to operate in fast fluidization regime; this will increase the

  9. Gasification of sawdust in pressurised internally circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Maartensson, R.; Lindblom, M. [Lund Univ. (Sweden). Dept. of Chemical Engineering

    1996-12-31

    A test plant for pressurised gasification of biofuels in a internally circulating fluidized bed has been built at the department of Chemical Engineering II at the University of Lund. The design performance is set to maximum 20 bar and 1 050 deg C at a thermal input of 100 kW or a maximum fuel input of 18 kg/in. The primary task is to study pressurised gasification of biofuels in relation to process requirements of the IGCC concept (integrated gasification combined cycle processes), which includes studies in different areas of hot gas clean-up in reducing atmosphere for gas turbine applications. (orig.)

  10. Gasification of sawdust in pressurised internally circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Maartensson, R; Lindblom, M [Lund Univ. (Sweden). Dept. of Chemical Engineering

    1997-12-31

    A test plant for pressurised gasification of biofuels in a internally circulating fluidized bed has been built at the department of Chemical Engineering II at the University of Lund. The design performance is set to maximum 20 bar and 1 050 deg C at a thermal input of 100 kW or a maximum fuel input of 18 kg/in. The primary task is to study pressurised gasification of biofuels in relation to process requirements of the IGCC concept (integrated gasification combined cycle processes), which includes studies in different areas of hot gas clean-up in reducing atmosphere for gas turbine applications. (orig.)

  11. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project. Annual report, 1988

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    This Annual Report on Colorado-Ute Electric Association`s NUCLA Circulating Fluidized Bed (CFB) Demonstration Program covers the period from February 1987 through December 1988. The outline for presentation in this report includes a summary of unit operations along with individual sections covering progress in study plan areas that commenced during this reporting period. These include cold-mode shakedown and calibration, plant commercial performance statistics, unit start-up (cold), coal and limestone preparation and handling, ash handling system performance and operating experience, tubular air heater, baghouse operation and performance, materials monitoring, and reliability monitoring. During this reporting period, the coal-mode shakedown and calibration plan was completed. (VC)

  12. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    International Nuclear Information System (INIS)

    Unknown

    2001-01-01

    Foster Wheeler Development Corporation is working under DOE contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% while producing near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The unique aspect of the process is that it utilizes a pressurized circulating fluidized bed partial gasifier and does not attempt to consume the coal in a single step. To convert all the coal to syngas in a single step requires extremely high temperatures ((approx)2500 to 2800F) that melt and vaporize the coal and essentially drive all coal ash contaminants into the syngas. Since these contaminants can be corrosive to power generating equipment, the syngas must be cooled to near room temperature to enable a series of chemical processes to clean the syngas. Foster Wheeler's process operates at much lower temperatures that control/minimize the release of contaminants; this eliminates/minimizes the need for the expensive, complicated syngas heat exchangers and chemical cleanup systems typical of high temperature gasification. By performing the gasification in a circulating bed, a significant amount of syngas can still be produced despite the reduced temperature and the circulating bed allows easy scale up to large size plants. Rather than air, it can also operate with oxygen to facilitate

  13. Ten residual biomass fuels for circulating fluidized-bed gasification

    Energy Technology Data Exchange (ETDEWEB)

    Drift, A. van der; Doorn, J. van [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Vermeulen, J.W. [NV Afvalzorg, Haarlem (Netherlands)

    2001-07-01

    In co-operation with a Dutch company (NV Afvalzorg) and the Dutch agency for energy and environment (Novem), ECN has successfully tested 10 different biomass residues in its 500 kW{sub th} circulating fluidized-bed gasification facility. Among the fuels used as demolition wood (both puree and mixed with sewage sludge and paper sludge), verge grass, railroad ties, cacao shells and different woody fuels. Railroad ties turn out to contain very little (heavy) metals. Initially, fuel feeding problems often impeded smooth operation. Contrary to feeding systems, the circulating fluidized-bed gasification process itself seems very flexible concerning the conversion of different kinds of biomass fuels. The fuel moisture content is one of the most important fuel characteristics. More moisture means that more air is needed to maintain the process temperature resulting in better carbon conversion and lower tar emission but also lower product gas heating value and lower cold gas efficiency. So, for a good comparison of the gasification behaviour of different fuels, the moisture content should be similar. However, the moisture content should be defined on an ash-free basis rather than on total mass (the usual way). Some of the ashes produced and retained in the second cyclone were analysed both for elemental composition and leaching behaviour. It turned out that the leaching rate of Mo and Br, elements only present in small concentrations, are preventing the ash to be considered as inert material according to the Dutch legislation for dumping on landfill sites. (Author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

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

  15. Nucla circulating atmospheric fluidized bed demonstration project. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute`s decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  16. Attempts on cardoon gasification in two different circulating fluidized beds

    Directory of Open Access Journals (Sweden)

    Chr. Christodoulou

    2014-11-01

    Full Text Available Few tests have been carried out in order to evaluate the use of cardoon in gasification and combustion applications most of the researchers dealt with agglomeration problems. The aim of this work is to deal with the agglomeration problem and to present a solution for the utilization of this biofuel at a near industrial application scale. For this reason, two experiments were conducted, one in TU Delft and one in Centre for Research and Technology Hellas (CERTH, using fuel cardoon and 50% w/w cardoon blended with 50% w/w giant reed respectively. Both experimental campaigns were carried out in similar atmospheric circulating fluidized bed gasifiers. Apart from the feedstock, the other differences were the gasification medium and the bed material used in each trial. The oxidizing agent at TUD׳s run was O2/steam, whereas CERTH׳s tests used air. When experiments with the cardoon 50% w/w–giant reed 50% w/w blend were performed no agglomeration problems were presented. Consequently, gasification could be achieved in higher temperature than that of pure cardoon which led to the reduction of tar concentration.

  17. Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars-Erik; Dam-Johansen, Kim

    1996-01-01

    The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O in the comb......The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O...... in the combustion chamber and the cyclone was calculated taking three mechanisms into account: Reduction by char, catalytic decomposition over bed material and thermal decomposition. The calculated destruction rate was in good agreement with the measured destruction of N2O injected at different levels in the boiler...

  18. Integrated drying and incineration of wet sewage sludge in combined bubbling and circulating fluidized bed units.

    Science.gov (United States)

    Li, Shiyuan; Li, Yunyu; Lu, Qinggang; Zhu, Jianguo; Yao, Yao; Bao, Shaolin

    2014-12-01

    An original integrated drying and incineration technique is proposed to dispose of sewage sludge with moisture content of about 80% in a circulating fluidized bed. This system combines a bubbling fluidized bed dryer with a circulating fluidized bed incinerator. After drying, sewage sludge with moisture less than 20% is transported directly and continuously from the fluidized bed dryer into a circulating fluidized bed incinerator. Pilot plant results showed that integrated drying and incineration is feasible in a unique single system. A 100 t/d Sewage Sludge Incineration Demonstration Project was constructed at the Qige sewage treatment plant in Hangzhou City in China. The operational performance showed that the main operation results conformed to the design values, from which it can be concluded that the scale-up of this technique is deemed both feasible and successful. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Model-free adaptive control of supercritical circulating fluidized-bed boilers

    Science.gov (United States)

    Cheng, George Shu-Xing; Mulkey, Steven L

    2014-12-16

    A novel 3-Input-3-Output (3.times.3) Fuel-Air Ratio Model-Free Adaptive (MFA) controller is introduced, which can effectively control key process variables including Bed Temperature, Excess O2, and Furnace Negative Pressure of combustion processes of advanced boilers. A novel 7-input-7-output (7.times.7) MFA control system is also described for controlling a combined 3-Input-3-Output (3.times.3) process of Boiler-Turbine-Generator (BTG) units and a 5.times.5 CFB combustion process of advanced boilers. Those boilers include Circulating Fluidized-Bed (CFB) Boilers and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.

  20. Numerical simulation of a full-loop circulating fluidized bed under different operating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yupeng [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Musser, Jordan M. [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Li, Tingwen [National Energy Technology Lab. (NETL), Morgantown, WV (United States); AECOM, Morgantown, WV (United States); Rogers, William A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

    2017-10-17

    Both experimental and computational studies of the fluidization of high-density polyethylene (HDPE) particles in a small-scale full-loop circulating fluidized bed are conducted. Experimental measurements of pressure drop are taken at different locations along the bed. The solids circulation rate is measured with an advanced Particle Image Velocimetry (PIV) technique. The bed height of the quasi-static region in the standpipe is also measured. Comparative numerical simulations are performed with a Computational Fluid Dynamics solver utilizing a Discrete Element Method (CFD-DEM). This paper reports a detailed and direct comparison between CFD-DEM results and experimental data for realistic gas-solid fluidization in a full-loop circulating fluidized bed system. The comparison reveals good agreement with respect to system component pressure drop and inventory height in the standpipe. In addition, the effect of different drag laws applied within the CFD simulation is examined and compared with experimental results.

  1. Design and simulation of a circulating fluidized bed to clean the products of biomass gasification

    Energy Technology Data Exchange (ETDEWEB)

    Uchoa Neto, Moises; Carvalho, Yuri de Araujo [Dept. de Engenharia Mecanica. Faculdade de Tecnologia. Universidade de Brasilia, DF (Brazil); Oliveira, Taygoara Felamingo de; Barcelos, Manuel [Faculdade do Gama. Universidade de Brasilia, Gama, DF (Brazil)], e-mail: taygoara@unb.br

    2010-07-01

    The main goal of this work is to design a workbench circulating fluidized bed to study the cracking of tar in gases from the processes of biomass gasification. For this, a design methodology based on analytical results and empirical correlations for fluidized beds was employed. In parallel, a numerical code of open source technology (MFIX) for the solution of the transport equations of the multiphase flow in the column of a fluidized bed was used to give support to the choice of the design elements. The whole project of the workbench fluidized bed was completely developed, whose operation parameters such as bed geometry, gas velocity, circulating ratio and void fraction characterize a fast fluidization process. A preliminary mesh convergence study was executed with the numerical tool, that was validated comparing with analytical results. Among the most important results, the code computed the predicted value for the minimum fluidization. (author)

  2. Circulating hyaluronate: concentration in different vascular beds in man

    DEFF Research Database (Denmark)

    Bentsen, K D; Henriksen, Jens Henrik Sahl; Laurent, T C

    1986-01-01

    The plasma concentration of hyaluronate (hyaluronic acid; HA) was measured in different vascular beds in order to determine regional kinetics of endogenous HA in fasting, supine subjects with normal (n = 6) or moderately decreased kidney function (n = 9). In both groups hepatic venous HA was sign......The plasma concentration of hyaluronate (hyaluronic acid; HA) was measured in different vascular beds in order to determine regional kinetics of endogenous HA in fasting, supine subjects with normal (n = 6) or moderately decreased kidney function (n = 9). In both groups hepatic venous HA...

  3. Fluidization behavior in a circulating slugging fluidized bed reactor. Part II: Plug characteristics

    NARCIS (Netherlands)

    van Putten, I.C.; van Sint Annaland, M.; Weickert, G.

    2007-01-01

    In the transporting square nosed slugging fluidization regime (0.4 < u0 < 1.0m/s) a bed of polyethylene powder with a low density (ρ = 900/kg/m3) and a large particle size distribution (70 < dρ < 1600µm) was operated in two circulating fluidized bed systems (riser diameters 0.044 and 0.105 m). A

  4. Refractory experience in circulating fluidized bed combustors, Task 7. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, R.Q.

    1989-11-01

    This report describes the results of an investigation into the status of the design and selection of refractory materials for coal-fueled circulating fluidized-bed combustors. The survey concentrated on operating units in the United States manufactured by six different boiler vendors: Babcock and Wilcox, Combustion Engineering, Foster Wheeler, Keeler Dorr-Oliver, Pyropower, and Riley Stoker. Information was obtained from the boiler vendors, refractory suppliers and installers, and the owners/operators of over forty units. This work is in support of DOE`s Clean Coal Technology program, which includes circulating fluidized-bed technology as one of the selected concepts being evaluated.

  5. Steam gasification of coal using a pressurized circulating fluidized bed

    International Nuclear Information System (INIS)

    Werner, K.F.J.

    1989-09-01

    Subject of this investigation is the process engineering of a coal gasification using nuclear heat. A special aspect is the efficiency. To this purpose a new method for calculating the kinetics of hard coal steam gasification in a fluidized bed is presented. It is used for evaluations of gasification kinetics in a large-scale process on the basis of laboratory-scale experiments. The method is verified by experimental data from a large-scale gasifier. The investment costs and the operating costs of the designed process are estimated. (orig.) [de

  6. Hydrodynamics of a hybrid circulating fluidized bed reactor with a partitioned loop seal system

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Dal-Hee; Moon, Jong-Ho; Jin, Gyoung Tae; Shun, Dowon [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Yun, Minyoung; Park, Chan Seung; Norbeck, Joseph M. [University of California, Riverside (United States)

    2015-07-15

    A circulating fluidized bed (CFB) with a hybrid design has been developed and optimized for steam hydrogasification. The hybrid CFB is composed of a bubbling fluidized bed (BFB) type combustor and a fast fluidized bed (FB) type gasifier. Char is burnt in the combustor and the generated heat is supplied to the gasifier along with the bed materials. Two different types of fluidized beds are connected to each other with a newly developed partitioned loop seal to avoid direct contact between two separate gas streams flowing in each fluidized bed. Gas mixing tests were carried out with Air and Argon in a cold model hybrid CFB to test the loop seal efficiency. Increase in solid inventory in the loop seal can improve the gas separation efficiency. It can be realized at higher gas velocity in fast bed and with higher solid inventory in the loop seal system. In addition, bed hydrodynamics was investigated with varying gas flow conditions and particle sizes in order to obtain a full understanding of changes of solid holdup in the FB. The solid holdup in the FB increased with increasing gas velocity in the BFB. Conversely, increase in gas velocity in the FB contributed to reducing the solid holdup in the FB. It was observed that changing the particle size of bed material does not have a big impact on hydrodynamic parameters.

  7. Hydrodynamics of a hybrid circulating fluidized bed reactor with a partitioned loop seal system

    International Nuclear Information System (INIS)

    Bae, Dal-Hee; Moon, Jong-Ho; Jin, Gyoung Tae; Shun, Dowon; Yun, Minyoung; Park, Chan Seung; Norbeck, Joseph M.

    2015-01-01

    A circulating fluidized bed (CFB) with a hybrid design has been developed and optimized for steam hydrogasification. The hybrid CFB is composed of a bubbling fluidized bed (BFB) type combustor and a fast fluidized bed (FB) type gasifier. Char is burnt in the combustor and the generated heat is supplied to the gasifier along with the bed materials. Two different types of fluidized beds are connected to each other with a newly developed partitioned loop seal to avoid direct contact between two separate gas streams flowing in each fluidized bed. Gas mixing tests were carried out with Air and Argon in a cold model hybrid CFB to test the loop seal efficiency. Increase in solid inventory in the loop seal can improve the gas separation efficiency. It can be realized at higher gas velocity in fast bed and with higher solid inventory in the loop seal system. In addition, bed hydrodynamics was investigated with varying gas flow conditions and particle sizes in order to obtain a full understanding of changes of solid holdup in the FB. The solid holdup in the FB increased with increasing gas velocity in the BFB. Conversely, increase in gas velocity in the FB contributed to reducing the solid holdup in the FB. It was observed that changing the particle size of bed material does not have a big impact on hydrodynamic parameters

  8. Identification and MPC control of a circulation fluidized bed boiler using an LPV model

    NARCIS (Netherlands)

    Huang, J.; Ji, G.; Zhu, Y.; Lin, W.; Kothare, M.; Tade, M.; Vande Wouwer, A.; Smets, I.

    2010-01-01

    This work studies the identification and control of circulation fluidized bed (CFB) boilers. The CFB boiler under investigation shows strong nonlinearity due to big changes of steam load. A linear parameter varying (LPV) model is used to represent the process dynamics and used in control. The steam

  9. Exergy analysis of a circulating fluidized bed boiler cogeneration power plant

    International Nuclear Information System (INIS)

    Gürtürk, Mert; Oztop, Hakan F.

    2016-01-01

    Highlights: • Analysis of energy and exergy for a cogeneration power plant have been performed. • This plant has circulating fluidized bed boiler. • Energy and exergy efficiencies of the boiler are obtained as 84.65% and 29.43%, respectively. • Exergy efficiency of the plant was calculated as 20%. - Abstract: In this study, energy and exergy analysis of a cogeneration power plant have been performed. The steam which is produced by the cogeneration power plant is used for salt production and most important part of the cogeneration power plant is the circulation fluidized bed boiler. Energy and exergy efficiency of the circulation fluidized bed boiler were found as 84.65% and 29.43%, respectively. Exergy destruction of the circulation fluidized bed boiler was calculated as 21789.39 kW and 85.89% of exergy destruction in the plant. The automation system of the cogeneration power plant is insufficient. Exergy efficiency of the plant was calculated as 20%. Also, some design parameters increasing energy losses were determined.

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

    Czech Academy of Sciences Publication Activity Database

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

    2008-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-10-30

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

  12. Validation of a two-fluid model used for the simulation of dense fluidized beds; Validation d`un modele a deux fluides applique a la simulation des lits fluidises denses

    Energy Technology Data Exchange (ETDEWEB)

    Boelle, A.

    1997-02-17

    A two-fluid model applied to the simulation of gas-solid dense fluidized beds is validated on micro scale and on macro scale. Phase coupling is carried out in the momentum and energy transport equation of both phases. The modeling is built on the kinetic theory of granular media in which the gas action has been taken into account in order to get correct expressions of transport coefficients. A description of hydrodynamic interactions between particles in high Stokes number flow is also incorporated in the model. The micro scale validation uses Lagrangian numerical simulations viewed as numerical experiments. The first validation case refers to a gas particle simple shear flow. It allows to validate the competition between two dissipation mechanisms: drag and particle collisions. The second validation case is concerted with sedimenting particles in high Stokes number flow. It allows to validate our approach of hydrodynamic interactions. This last case had led us to develop an original Lagrangian simulation with a two-way coupling between the fluid and the particles. The macro scale validation uses the results of Eulerian simulations of dense fluidized bed. Bed height, particles circulation and spontaneous created bubbles characteristics are studied and compared to experimental measurement, both looking at physical and numerical parameters. (author) 159 refs.

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

    OpenAIRE

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

    2015-01-01

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

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

    DEFF Research Database (Denmark)

    Narayan, Vikas

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

  15. Effect of flue gas recirculation on heat transfer in a supercritical circulating fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    Błaszczuk Artur

    2015-09-01

    Full Text Available This paper focuses on assessment of the effect of flue gas recirculation (FGR on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB combustor. The performance test in supercritical CFB combustor with capacity 966 MWth was performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-04-30

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-09-01

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

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

    International Nuclear Information System (INIS)

    Su, Mingze; Zhao, Haibo; Ma, Jinchen

    2015-01-01

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

  19. Experimental investigation on a 0.35 MWth coal-fired horizontal circulating fluidized bed boiler

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Aihong; Li, Qinghai; Zhang, Yanguo; Wang, Zhaojun; Dang, Wenda [Tsinghua Univ., Beijing (China); Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering

    2013-07-01

    The capacities of industrial coal-fired boilers are normally less than 20-30 MWe. And these coal-fired boilers of low capacity are facing the severe situation of low efficiency and heavy environmental pollution. Hence, an innovative horizontal circulating fluidized bed (HCFB) boiler was developed to enhance heat efficiency and reduce pollutant emission of industrial boilers in China. The chamber in the HCFB boiler consists of primary combustion chamber, secondary combustion chamber and burnout chamber, which were combined horizontally side by side. To verify the conception of horizontal fluidized circulation and to obtain the characteristic data, a 0.35 MWth coal-combustion HCFB boiler was designed and installed to perform some experiments of combustion and mass circulation. In the boiler there were two mass circulating paths, one is inner circulating through the inertia separator and another was external circulating through the cyclone separator. The connection bottom of the secondary chamber and the burnout chamber was designed as an inertia separator, in which separated and collected solid materials were returned to the primary combustion. In fact the secondary separator was a small cyclone separator connecting to the exit of the burnout chamber. Heat efficiency and separating efficiency of the experimental boiler were measured and analyzed. Furthermore, mass and temperature distribution along the chambers height were also investigated. The results showed that the heat efficiency of the bare boiler was 82%. The mass balance based on ash content was measured and analyzed. Separating efficiency of the inertia separator and cyclone separator was 60 and 99.9%, respectively. It showed that the two stage material separation and circulation enhanced coal combustion in the HCFB boiler and help to minimize the height of the furnace.

  20. Influence of Bubble-Bubble interactions on the macroscale circulation patterns in a bubbling gas-solid fluidized bed

    NARCIS (Netherlands)

    Laverman, J.A.; van Sint Annaland, M.; Kuipers, J.A.M.

    2007-01-01

    The macro-scale circulation patterns in the emulsion phase of a gas-solid fluidized bed in the bubbling regime have been studied with a 3D Discrete Bubble Model. It has been shown that bubble-bubble interactions strongly influence the extent of the solids circulation and the bubble size

  1. Controlling thermal properties of dense gas fluidized beds for concentrated solar power by internal and external solids circulation

    Science.gov (United States)

    Ammendola, Paola; Bareschino, Piero; Chirone, Riccardo; Salatino, Piero; Solimene, Roberto

    2017-06-01

    Fluidization technology displays a long record of success stories, mostly related to applications to thermal and thermochemical processes, which are fostering extension to novel and relatively unexplored fields. Application of fluidized beds to collection and thermal storage of solar radiation in Concentrated Solar Power (CSP) is one of the most promising, a field which poses challenging issues and great opportunities to fluidization scientists and technologists. The potential of this growing field calls for reconsideration of some of the typical design and operation guidelines and criteria, with the goal of exploiting the inherently good thermal performances of gas-fluidized beds at their best. "Creative" and non-conventional design and operation of fluidized beds, like those based on internal and external solids circulation, may be beneficial to the enhancement of thermal diffusivity and surface-to-bed heat transfer, improving the potential for application in the very demanding context of CSP with thermal energy storage. This paper investigated: i) a fluidized bed configuration with an uneven distribution of the fluidizing gas to promote vortices in the scale of bed height (internal solids circulation); ii) a dual fluidized bed configuration characterized by an external solids circulation achieved by the operation of a riser and a bubbling fluidized bed. CFD simulations showed the hydrodynamics conditions under which the internal solids circulation was established. The hydrodynamic characterization of the external solids circulation was achieved by an experimental study carried out with different cold models. The dual fluidized bed system was optimized in terms of operating conditions and geometrical features of the connections between two fluidized beds.

  2. The study of solid circulation rate in a compartmented fluidized bed gasifier (CFBG)

    Science.gov (United States)

    Wee, S. K.; Pok, Y. W.; Law, M. C.; Lee, V. C. C.

    2016-06-01

    Biomass waste has been abundantly available in Malaysia since the booming of palm oil industry. In order to tackle this issue, gasification is seen a promising technology to convert waste into energy. In view of the heat requirement for endothermic gasification reaction as well as the complex design and operation of multiple fluidized beds, compartmented fluidized bed gasifier (CFBG) with the combustor and the gasifier as separate compartments is proposed. As such, solid circulation rate (SCR) is one of the essential parameters for steady gasification and combustion to be realized in their respective compartments. Experimental and numerical studies (CFD) on the effect of static bed height, main bed aeration, riser aeration and v-valve aeration on SCR have been conducted in a cold- flow CFBG model with only river sand as the fluidizing medium. At lower operating range, the numerical simulations under-predict the SCR as compared to that of the experimental results. Also, it predicts slightly different trends over the range. On the other hand, at higher operating range, the numerical simulations are able to capture those trends as observed in the experimental results at the lower operating range. Overall, the numerical results compare reasonably well with that of the experimental works.

  3. Prospects for using the technology of circulating fluidized bed for technically refitting Russian thermal power stations

    Science.gov (United States)

    Ryabov, G. A.; Folomeev, O. M.; Litun, D. S.; Sankin, D. A.; Dmitryukova, I. G.

    2009-01-01

    The present state and development of circulating fluidized bed (CFB) technology around the world are briefly reviewed. Questions of increasing the capacity of single boiler units and raising the parameters of steam are discussed. CFB boilers for 225- and 330-MW power units are described and their parameters are estimated as applied to the conditions of firing different Russian fuels. Indicators characterizing CFB boilers and pulverized-coal boilers are given. Capital outlays and operational costs for new coal-fired units are compared, and the results from this comparison are used to show the field of the most promising use of the CFB technology during technical refitting of Russian thermal power stations.

  4. Circulating fluidized-bed technologies for the conversion of biomass into energy

    International Nuclear Information System (INIS)

    Greil, C.; Hirschfelder, H.

    1995-01-01

    The paper introduces circulating fluidized-bed (CFB) combustion and CFB gasification. CFB combustion units are state-of-the-art and have proven their ability to convert biomass into power and/or steam. The existing units and projects in developing countries are discussed as examples of conventional technology. To illustrate advanced technologies, CFB gasification is discussed. Important process parameters of plants already in operation or under construction in developed countries are shown, Criteria for the selection of CFB combustion or gasification based on available feedstocks and products required are discussed. Finally, a procedure for implementing Lurgi's CFB technology in developing countries is proposed. (author)

  5. PIV Visualization of Bubble Induced Flow Circulation in 2-D Rectangular Pool for Ex-Vessel Debris Bed Coolability

    Energy Technology Data Exchange (ETDEWEB)

    Han, Teayang; Kim, Eunho; Park, Hyun Sun; Moriyama, Kiyofumi [POSTECH, Pohang (Korea, Republic of)

    2015-10-15

    The previous research works demonstrated the debris bed formation on the flooded cavity floor in experiments. Even in the cases the core melt is once solidified, the debris bed can be re-melted due to the decay heat. If the debris bed is not cooled enough by the coolant, the re-melted debris bed will react with the concrete base mat. This situation is called the molten core-concrete interaction (MCCI) which threatens the integrity of the containment by generated gases which pressurize the containment. Therefore securing the long term coolability of the debris bed in the cavity is crucial. According to the previous research works, the natural convection driven by the rising bubbles affects the coolability and the formation of the debris bed. Therefore, clarification of the natural convection characteristics in and around the debris bed is important for evaluation of the coolability of the debris bed. In this study, two-phase flow around the debris bed in a 2D slice geometry is visualized by PIV method to obtain the velocity map of the flow. The DAVINCI-PIV was developed to investigate the flow around the debris bed. In order to simulate the boiling phenomena induced by the decay heat of the debris bed, the air was injected separately by the air chamber system which consists of the 14 air-flowmeters. The circulation flow developed by the rising bubbles was visualized by PIV method.

  6. Predictive models of circulating fluidized bed combustors: SO[sub 2] sorption in the CFB loop

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D.; Therdthianwong, A. (Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering)

    1993-02-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Sorption of S0[sub 2] with calcined limestone was studied in a PYROFLOW type CFB loop at conditions approximating those found in a CFB combustor. Initially the CFB loop contained 150 micron CaO particles of a density of 3.3 g/cm[sup 3] and air at 1143[degrees]K and 3.25 atm. Atzero time, air containing 600 ppm SO[sub 2], was introduced into the riser bottom at 1143[degrees]K. The effect of gas velocity, sorbent inventory and inlet pressure on the sorption of SO[sub 2], were studied isothermally by running our hydrodynamic code with the S0[sub 2] sorption conservation of species equation. At a velocity of 5m/sec., reported to be a typical velocity by PYROPOWER, there is reasonably good S0[sub 2] removal. At 10 m/sec the S0[sub 2] removal is poor. The best SO[sub 2], removal is for a velocity of 5 m/s and a high bed inventory, initial bed height, H = 9m. Most of the S0[sub 2] is removed in the first two meters of the reactor. However, the S0[sub 2] removal is not complete at the bed outlet. This is due to mixing. At the left wall of the reactor (wall opposite the solids inlet) the S0[sub 2] removal was poor due to gas bypassing caused by the asymmetrical solids inlet. Simulation of the PYROPOWER loop with a symmetrical inlet gave us an order of magnitude improvement over the conventional PYROPOWER system. These results demonstrate the practical utility of the predictive model that we have developed over the last three years.

  7. Experimental study of gas–liquid two-phase flow through packed bed under natural circulation conditions

    International Nuclear Information System (INIS)

    Chen, Shao-Wen; Miwa, Shuichiro; Griffiths, Matt

    2016-01-01

    Dry-out phenomena in packed beds or porous media may cause a significant digression of cooling/reaction performance in heat transfer/chemical reactor systems. One of the phenomena responsible for the dry-out in packed beds is known as the counter-current flow limitation (CCFL). In order to investigate the CCFL phenomena induced by gas–liquid two-phase flow in packed beds inside a pool, a natural circulation packed bed test facility was designed and constructed. A total of 27 experimental conditions covering various packing media sizes (sphere diameters: 3.0, 6.4 and 9.5 mm), packed bed heights (15, 35 and 50 cm) and water level heights (1.0, 1.5 and 2.0 m) were tested to examine the CCFL criteria with adiabatic air–water two-phase flow under natural circulation conditions. Both CCFL and flow reversal phenomena were observed, and the experimental data including instantaneous and time-averaged void fraction, differential pressure and superficial gas–liquid velocities were collected. The CCFL criteria were determined when periodical oscillations of void fraction and differential pressure appear. In addition, the Wallis correlation for CCFL was utilized for data analysis, and the Wallis coefficient, C, was determined experimentally from the packed bed CCFL tests. Compared to the existing data-sets in literature, the higher C values obtained in the present experiment suggest a possibly higher dry-out heat flux for natural circulation debris systems, which may be due to the water supply from both top and bottom surfaces of the packed beds. Considering the effects of bed height and hydraulic diameter of the packing media, a newly developed model for the Wallis coefficient, C, under natural circulation CCFL is presented. The present model can predict the experimental data with an averaged absolute error of ±7.9%. (author)

  8. Occurrence of polycyclic aromatic hydrocarbons in dust emitted from circulating fluidized bed boilers.

    Science.gov (United States)

    Kozielska, B; Konieczyńiski, J

    2008-11-01

    Occurrence of polycyclic aromatic hydrocarbons (PAHs) in granulometric fractions of dust emitted from a hard coal fired circulating fluidized bed (CFB) boiler was investigated. The dust was sampled with the use of a Mark III impactor. In each fraction of dust, by using gas chromatography (GC), 16 selected PAHs and total PAHs were determined and the toxic equivalent B(a)P (TE B(a)P) was computed. The results, recalculated for the standard granulometric fractions, are presented as concentrations and content of the determined PAHs in dust. Distributions of PAHs and their profiles in the granulometric dust fractions were studied also. The PAHs in dust emitted from the CFB boiler were compared with those emitted from mechanical grate boilers; a distinctly lower content of PAHs was found in dust emitted from the former.

  9. The prediction of heat transfer coefficient in circulating fluidized bed combustors

    International Nuclear Information System (INIS)

    Hamdan, M.A.; Al-qaq, A.M.

    2008-01-01

    In the present work, a theoretical study is performed to modify an existing model that is used to predict the heat transfer coefficient in circulating fluidized bed combustors. In the model, certain parameters were used as being of constant values, which leads to an error in the obtained value of the heat transfer coefficient. In this study and as a first step, the model is thoroughly studied and then the variation of the coefficient with these parameters is presented. Having done that, correlation for these parameters are obtained and then used in the model. Finally the modified model was tested against previously experimental and theoretical data that is available in literature. It was found that the accuracy of the model has been improved after it has been modified

  10. The prediction of heat transfer coefficient in circulating fluidized bed combustors

    Energy Technology Data Exchange (ETDEWEB)

    Hamdan, M.A.; Al-qaq, A.M. [Department of Mechanical Engineering, University of Jordan Amman, Qween Rania Street, Amman, AL Jbeeha 11942 (Jordan)

    2008-11-15

    In the present work, a theoretical study is performed to modify an existing model that is used to predict the heat transfer coefficient in circulating fluidized bed combustors. In the model, certain parameters were used as being of constant values, which leads to an error in the obtained value of the heat transfer coefficient. In this study and as a first step, the model is thoroughly studied and then the variation of the coefficient with these parameters is presented. Having done that, correlation for these parameters are obtained and then used in the model. Finally the modified model was tested against previously experimental and theoretical data that is available in literature. It was found that the accuracy of the model has been improved after it has been modified. (author)

  11. Analysis of microalgae pellets combustion in a circulating fluidized-bed

    Directory of Open Access Journals (Sweden)

    Kosowska-Golachowska Monika

    2017-01-01

    Full Text Available Microalgae are expected to become an important source of highvalue products with several applications in a large number of areas of biotechnology and, especially, in biofuels production. The increasing interest in microalgae as a source of biofuel (so-called third generation biofuel is due to the several advantages. The objective of this study was to investigate combustion characteristics of microalgae (Oscillatoria sp. pellets burnt in a circulating fluidized-bed (CFB in terms of sample temperature profiles, ignition time, ignition temperature, devolatilization time and the burnout time. Spherical 10-mm microalgae pellets were tested at temperature of 850°C in a 12-kW bench-scale CFB combustor.

  12. Circulating fluidized-bed technologies for the conversion of biomass into energy

    Energy Technology Data Exchange (ETDEWEB)

    Greil, C; Hirschfelder, H [Lurgi Energid und Umwelt GmbH, Frankfurt am Main (Germany)

    1995-12-01

    The paper introduces circulating fluidized-bed (CFB) combustion and CFB gasification. CFB combustion units are state-of-the-art and have proven their ability to convert biomass into power and/or steam. The existing units and projects in developing countries are discussed as examples of conventional technology. To illustrate advanced technologies, CFB gasification is discussed. Important process parameters of plants already in operation or under construction in developed countries are shown, Criteria for the selection of CFB combustion or gasification based on available feedstocks and products required are discussed. Finally, a procedure for implementing Lurgi`s CFB technology in developing countries is proposed. (author) 7 refs, 4 figs, 3 tabs

  13. Circulating fluidized bed hydrodynamics experiments for the multiphase fluid dynamics research consortium (MFDRC).

    Energy Technology Data Exchange (ETDEWEB)

    Oelfke, John Barry; Torczynski, John Robert; O' Hern, Timothy John; Tortora, Paul Richard; Bhusarapu, Satish (; ); Trujillo, Steven Mathew

    2006-08-01

    An experimental program was conducted to study the multiphase gas-solid flow in a pilot-scale circulating fluidized bed (CFB). This report describes the CFB experimental facility assembled for this program, the diagnostics developed and/or applied to make measurements in the riser section of the CFB, and the data acquired for several different flow conditions. Primary data acquired included pressures around the flow loop and solids loadings at selected locations in the riser. Tomographic techniques using gamma radiation and electrical capacitance were used to determine radial profiles of solids volume fraction in the riser, and axial profiles of the integrated solids volume fraction were produced. Computer Aided Radioactive Particle Tracking was used to measure solids velocities, fluxes, and residence time distributions. In addition, a series of computational fluid dynamics simulations was performed using the commercial code Arenaflow{trademark}.

  14. Operating experience - electrostatic precipitators as deduster for circulating fluidized bed boilers

    Energy Technology Data Exchange (ETDEWEB)

    Frank, M.J.; Bork, G. [Lurgi Lentjes Bischoff GmbH (Germany)

    1999-07-01

    Electrostatic precipitators (ESPs) are widely used for dedusting flue gases generated by steam generators with circulating fluidized bed (CFB) furnaces. In such applications, limestone is used as a desulphurisation additive in the furnace, eliminating the need for further desulphurisation systems downstream. However, the additive changes the physical properties of the particulate matter to be removed by the ESP, mostly unfavourably as regards ash resistivity. In this paper, design criteria and operating experiences are discussed, showing the main influences attributable to the additive and the CFB operating regime. Specific reference is made to the Heizkraftwerk 1 CFB power plant (Germany). Designed for domestic coals, on switching to import coals boiler output at the plant had to be limited due to unacceptably high dust emissions. ESP efficiency was optimised in two ways: (1) flow distribution was improved; and (2) new microprocessor controllers installed. Results of the modifications are discussed.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  16. Biomass gasification in a circulating fluidized bed; Vergasung von Biomasse in der zirkulierenden Wirbelschicht

    Energy Technology Data Exchange (ETDEWEB)

    Ising, M; Hoelder, D; Backhaus, C; Althaus, W [Fraunhofer Inst. fuer Umwelt-, Sicherheits- und Energietechnik UMSICHT, Oberhausen (Germany)

    1998-09-01

    Biomass gasification in a circulating fluidized bed, in combination with a gas engine or gas burner, is a promising option for energetic use of biomass. Economic efficiency analyses on the basis of the UMSICHT plant show that this technology for combined heat and power generation from biomass is promising also for the range below 10 MW. The economic situation of any plant must be considered for the specific boundary conditions imposed by the power supply industry. The feasibility of the process was tested in a demonstration plant at Oberhausen. The plant was optimized further in extensive test series, and a number of tar reduction processes were investigated and improved on. The authors now intend to prove that gasification in a circulating fluidized bed combined with a gas engine cogeneration plant is feasible in continuous operation. (orig./SR) [Deutsch] Die Vergasung von Biomasse in der zirkulierenden Wirbelschicht ist in Kombination mit einem Gasmotor oder einem Gasbrenner eine vielversprechende Option fuer die energetische Biomassenutzung. Wirtschaftlichkeitsbetrachtungen auf Basis der UMSICHT-Anlage zeigen, dass diese Technologie fuer die gekoppelte Strom- und Waermeerzeugung aus Biomasse auch im Leistungsbereich unter 10 MW grosse Chancen verspricht. Dabei ist die oekonomische Situation einer Anlage im Einzelfall unter Beachtung der energiewirtschaftlichen Randbedingungen zu beurteilen. Durch den Betrieb einer Demonstrationsanlage in Oberhausen konnte die Funktion des Verfahrens nachgewiesen werden. In weiteren umfangreichen Versuchsreihen werden die Anlage weiter optimiert und verschiedene Konzepte zur Teerminderung untersucht und weiterentwickelt. Angestrebt ist der Nachweis des Dauerbetriebs von ZWS-Vergasung zusammen mit dem Gasmotoren-BHKW. (orig./SR)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

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

  18. Comparative modeling of biological nutrient removal from landfill leachate using a circulating fluidized bed bioreactor (CFBBR).

    Science.gov (United States)

    Eldyasti, Ahmed; Andalib, Mehran; Hafez, Hisham; Nakhla, George; Zhu, Jesse

    2011-03-15

    Steady state operational data from a pilot scale circulating fluidized bed bioreactor (CFBBR) during biological treatment of landfill leachate, at empty bed contact times (EBCTs) of 0.49, and 0.41 d and volumetric nutrients loading rates of 2.2-2.6 kg COD/(m(3)d), 0.7-0.8 kg N/(m(3)d), and 0.014-0.016 kg P/(m(3)d), was used to calibrate and compare developed process models in BioWin(®) and AQUIFAS(®). BioWin(®) and AQUIFAS(®) were both capable of predicting most of the performance parameters such as effluent TKN, NH(4)-N, NO(3)-N, TP, PO(4)-P, TSS, and VSS with an average percentage error (APE) of 0-20%. BioWin(®) underpredicted the effluent BOD and SBOD values for various runs by 80% while AQUIFAS(®) predicted effluent BOD and SBOD with an APE of 50%. Although both calibrated models, confirmed the advantages of the CFBBR technology in treating the leachate of high volumetric loading and low biomass yields due to the long solid retention time (SRT), both BioWin(®) and AQUIFAS(®) predicted the total biomass and SRT of CFBBR based on active biomass only, whereas in the CFBBR runs both active as well as inactive biomass accumulated. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Modeling of NO and N2O emissions from biomass circulating fluidized bed combustors

    International Nuclear Information System (INIS)

    Liu, H.; Gibbs, B.M.

    2002-01-01

    In order to correctly model biomass combustion in a circulating fluidized bed (CFB) combustor, it is necessary to examine the four main stages in the combustion of biomass particles. These include drying, devolatilization, volatile combustion and char combustion in a CFB combustor. This paper presents a newly developed model for nitric oxide (NO) and nitrous oxide (N 2 O) emissions from biomass-fired CFB combustors. A typical woody biomass of pinewood chips was selected for the model parameters. The drying and devolatilization of biomass particles was modeled with limited rates according to woody biomass fuels. The partition of fuel nitrogen between volatiles and char was chosen for pinewood based on available data from literature. It was assumed that the volatile nitrogen was composed of ammonia (NH 3 ), hydrogen cyanide (HCN) and nitrogen (N 2 ). The model included 25 chemical reactions, of which 20 belonged to global fuel-nitrogen reaction kinetics. A 12 MW CFB boiler was used to apply the model. Results were compared with experimental values as well as data from literature. The reaction between NO and char was found to be the key reaction that determines NO emissions. The catalytic effect of bed materials on the oxidation of NH 3 and the the homogeneous reaction of NH 3 with nitric oxide was also significant. 25 refs., 2 tabs., 5 figs

  20. 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.

  1. Influence of additives on selective noncatalytic reduction of nitric oxide with ammonia in circulating fluidized bed boilers

    DEFF Research Database (Denmark)

    Leckner, Bo; Karlsson, Maria; Dam-Johansen, Kim

    1991-01-01

    The application of selective noncatalytic reduction of nitric oxide with ammonia in circulating fluidized bed boilers is investigated. Special attention is directed to the use of additives to the ammonia so that the efficiency of the NO reduction at lower temperatures can be increased. Tests under...

  2. Fluidization behavior in a circulating slugging fluidized bed reactor. Part I : residence time and residence time distribution of polyethylene solids

    NARCIS (Netherlands)

    Putten, van I.C.; Sint Annaland, van M.; Weickert, G.

    2007-01-01

    Square nosed slugging fluidization behavior in a circulating fluidized bed riser using a polyethylene powder with a very wide particle size distribution was studied. In square nosed slugging fluidization the extent of mixing of particles of different size depends on the riser diameter, gas velocity,

  3. Fluidization behavior in a circulating slugging fluidized bed reactor. Part I: Residence time and residence time distribution of polyethylene solids

    NARCIS (Netherlands)

    van Putten, I.C.; van Sint Annaland, M.; Weickert, G.

    2007-01-01

    Square nosed slugging fluidization behavior in a circulating fluidized bed riser using a polyethylene powder with a very wide particle size distribution was studied. In square nosed slugging fluidization the extent of mixing of particles of different size depends on the riser diameter, gas velocity,

  4. Oxygen Carrier Aided Combustion (OCAC of Wood Chips in a Semi-Commercial Circulating Fluidized Bed Boiler Using Manganese Ore as Bed Material

    Directory of Open Access Journals (Sweden)

    Magnus Rydén

    2016-11-01

    Full Text Available Oxygen Carrier Aided Combustion (OCAC is realized by using an active oxygen-carrying bed material in fluidized bed boilers. The active material is reduced in fuel rich parts of the boiler and oxidized in air rich parts. Advantages could be achieved such as new mechanisms for oxygen transport in space and time. Here calcined manganese ore has been used as active bed material in a 12 MWth circulating fluidized bed boiler. The fuel was wood chips and the campaign lasted more than two weeks. From an operational point of view, manganese ore worked excellently. From the temperature profile of the boiler it can be concluded that fuel conversion was facilitated, especially in the dense bottom bed. The effect did not always translate to reduced emissions, which suggests that final combustion in the cyclone outlet was also influenced. Substituting 10% of the sand bed with manganese ore made it possible to reduce the air to fuel ratio without generating large amounts of CO. The use of 100% manganese ore resulted in higher emissions of CO than the sand reference, but, when combined sulphur feeding, dramatic reductions in CO emissions, up to 90% compared to sand reference, was achieved.

  5. Characterization of fluidization regime in circulating fluidized bed reactor with high solid particle concentration using computational fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chalermsinsuwan, Benjapon; Thummakul, Theeranan; Piumsomboon, Pornpote [Chulalongkorn University, Bangkok (Thailand); Gidaspow, Dimitri [Armour College of Engineering, Chicago (United States)

    2014-02-15

    The hydrodynamics inside a high solid particle concentration circulating fluidized bed reactor was investigated using computational fluid dynamics simulation. Compared to a low solid particle reactor, all the conventional fluidization regimes were observed. In addition, two unconventional fluidization regimes, circulating-turbulent and dense suspension bypassing regimes, were found with only primary gas injection. The circulating-turbulent fluidization regime showed uniformly dense solid particle distribution in all the system directions, while the dense suspension bypassing fluidization regime exhibited the flow of solid particles at only one side system wall. Then, comprehensive fluidization regime clarification and mapping were evaluated using in-depth system parameters. In the circulating-turbulent fluidization regime, the total granular temperature was low compared to the adjacent fluidization regimes. In the dense suspension bypassing fluidization regime, the highest total granular temperature was obtained. The circulating-turbulent and dense suspension bypassing fluidization regimes are suitable for sorption and transportation applications, respectively.

  6. Application of digital image processing methods on the cluster structure at the wall of a circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hai-guang; Zhao, Zeng-wu; Li, Bao-wei; Wu, Wen-fei [Inner Mongolia Univ. of Science and Technology, Baotou (China). School of Environment and Energy

    2013-07-01

    This paper describes experiments to investigate the cluster structure of gas-particle flow at the wall region of a circulating fluidized bed (CFB). The setup is in a cold scale-model circulating fluidized bed with a riser that has a 0.30 m 0.28 m cross-section and is 2.9 m tall. A video camera was utilized to visualize the cluster structure through a transparent Plexiglas wall. An image processing system was used to analyze images, which were obtained under different superficial gas velocities and solid circulating rates. The results show that distinctly different cluster structures exist in the different operating conditions, which the number, shape and size of the clusters are affected by main air flow.

  7. GREENHOUSE GAS EMISSIONS CONTROL BY OXYGEN FIRING IN CIRCULATING FLUIDIZED BED BOILERS

    Energy Technology Data Exchange (ETDEWEB)

    Nsakala ya Nsakala; Gregory N. Liljedahl

    2003-05-15

    Given that fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic CO{sub 2} emissions. In this study, ALSTOM Power Inc. (ALSTOM) has investigated several coal fired power plant configurations designed to capture CO{sub 2} from effluent gas streams for use or sequestration. Burning fossil fuels in mixtures of oxygen and recirculated flue gas (made principally of CO{sub 2}) essentially eliminates the presence of atmospheric nitrogen in the flue gas. The resulting flue gas is comprised primarily of CO{sub 2}. Oxygen firing in utility scale Pulverized Coal (PC) fired boilers has been shown to be a more economical method for CO{sub 2} capture than amine scrubbing (Bozzuto, et al., 2001). Additionally, oxygen firing in Circulating Fluid Bed Boilers (CFB's) can be more economical than in PC or Stoker firing, because recirculated gas flow can be reduced significantly. Oxygen-fired PC and Stoker units require large quantities of recirculated flue gas to maintain acceptable furnace temperatures. Oxygen-fired CFB units, on the other hand, can accomplish this by additional cooling of recirculated solids. The reduced recirculated gas flow with CFB units results in significant Boiler Island cost savings. Additionally, ALSTOM has identified several advanced/novel plant configurations, which improve the efficiency and cost of the CO{sub 2} product cleanup and compression process. These advanced/novel concepts require long development efforts. An economic analysis indicates that the proposed oxygen-firing technology in circulating fluidized boilers could be developed and deployed economically in the near future in enhanced oil recovery (EOR) applications or enhanced gas recovery (EGR), such as coal bed methane recovery. ALSTOM received a Cooperative Agreement from the US

  8. Effect of operating conditions on performance of silica gel-water air-fluidised desiccant cooler

    Directory of Open Access Journals (Sweden)

    Rogala Zbigniew

    2017-01-01

    Full Text Available Fluidised desiccant cooling is reported in the literature as an efficient way to provide cooling for air-conditioning purposes. The performance of this technology can be described by electric and thermal Coefficients of Performance (COP and Specific Cooling Power (SCP. In this paper comprehensive theoretical study was carried out in order to assess the effect of operating conditions such as: superficial air velocity, desiccant particle diameter, bed switching time and desiccant filling height on the performance of fluidised desiccant cooler (FDC. It was concluded that FDC should be filled with as small as possible desiccant particles featuring diameters and should not be operated with shorter switching times than optimum. Moreover in order to efficiently run such systems superficial air velocities during adsorption and desorption should be similar. At last substantial effect of desiccant filling height on performance of FDC was presented.

  9. Modelling transient 3D multi-phase criticality in fluidised granular materials - the FETCH code

    International Nuclear Information System (INIS)

    Pain, C.C.; Gomes, J.L.M.A.; Eaton, M.D.; Ziver, A.K.; Umpleby, A.P.; Oliveira, C.R.E. de; Goddard, A.J.H.

    2003-01-01

    The development and application of a generic model for modelling criticality in fluidised granular materials is described within the Finite Element Transient Criticality (FETCH) code - which models criticality transients in spatial and temporal detail from fundamental principles, as far as is currently possible. The neutronics model in FETCH solves the neutron transport in full phase space with a spherical harmonics angle of travel representation, multi-group in neutron energy, Crank Nicholson based in time stepping, and finite elements in space. The fluids representation coupled with the neutronics model is a two-fluid-granular-temperature model, also finite element fased. A separate fluid is used to represent the liquid/vapour gas and the solid fuel particle phases, respectively. Particle-particle, particle-wall interactions are modelled using a kinetic theory approach on an analogy between the motion of gas molecules subject to binary collisions and granular flows. This model has been extensively validated by comparison with fluidised bed experimental results. Gas-fluidised beds involve particles that are often extremely agitated (measured by granular temperature) and can thus be viewed as a particularly demanding application of the two-fluid model. Liquid fluidised systems are of criticality interest, but these can become demanding with the production of gases (e.g. radiolytic and water vapour) and large fluid/particle velocities in energetic transients. We present results from a test transient model in which fissile material ( 239 Pu) is presented as spherical granules subsiding in water, located in a tank initially at constant temperature and at two alternative over-pressures in order to verify the theoretical model implemented in FETCH. (author)

  10. Limestone particle attrition and size distribution in a small circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Zhongxiang Chen; John R. Grace; C. Jim Lim [University of British Columbia, Vancouver, BC (Canada). Department of Chemical and Biological Engineering

    2008-06-15

    Limestone particle attrition was investigated in a small circulating fluidized bed reactor at temperatures from 25 to 850{sup o}C, 1 atm pressure and superficial gas velocities from 4.8 to 6.2 m/s. The effects of operating time, superficial gas velocity and temperature were studied with fresh limestone. No calcination or sulfation occurred at temperatures {le} 580{sup o}C, whereas calcination and sulfation affected attrition at 850{sup o}C. Increasing the temperature (while maintaining the same superficial gas velocity) reduced attrition if there was negligible calcination. Attrition was high initially, but after about 24 h, the rate of mass change became constant. The ratio of initial mean particle diameter to that at later times increased linearly with time and with (U{sub g} - U{sub mf}){sup 2}, while decreasing exponentially with temperature, with an activation energy for fresh limestone of -4.3 kJ/mol. The attrition followed Rittinger's surface theory. The change of surface area of limestone particles was proportional to the total excess kinetic energy consumed and to the total attrition time, whereas the change of surface area decreased exponentially with increasing temperature. At 850{sup o}C, the attrition rate of calcined lime was highest, whereas the attrition rate was lowest for sulfated particles. When online impact attrition was introduced, the attrition rate was about an order of magnitude higher than without impacts. 25 refs., 14 figs., 4 tabs.

  11. Investigation on energy storage and quick load change control of subcritical circulating fluidized bed boiler units

    International Nuclear Information System (INIS)

    Gao, Mingming; Hong, Feng; Liu, Jizhen

    2017-01-01

    Highlights: • The model of energy storage of subcritical CFB boilers is established. • The capacity and increment rate of heat storage are quantified. • A novel load control strategy is proposed to improve the quick load change ability. • An application on the 300 MW CFB unit proves the load change rate to 5–8 MW/min. - Abstract: The energy storage of circulating fluidized bed (CFB) boilers on fuel side cannot be ignored due to the special combustion type different from pulverized coal boilers. The sizable energy storage makes it possible for CFB units to enhance the quick load change ability and to increase the scale of new energy power connected into grid. Through mechanism analysis, the model of energy storage of subcritical CFB boilers has been established for the first time. Then by the project practice, the quantitative analysis is demonstrated for the capacity and control characteristics of energy storage on fuel side and steam water side. Based on the control characteristics and the transformation of the energy storage, a coordinated control system (CCS) control strategy named advanced energy balance (AEB) is designed to shorten the response time through the use of energy storage and to accelerate the load change speed of subcritical CFB units. Finally, a case study on a 300 MW CFB unit proves the feasibility of the proposed control strategy.

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

    Science.gov (United States)

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

    2018-01-01

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

  13. Characteristics modeling for supercritical circulating fluidized bed boiler working in oxy-combustion technology

    Directory of Open Access Journals (Sweden)

    Balicki Adrian

    2014-06-01

    Full Text Available Among the technologies which allow to reduce greenhouse gas emission, mainly carbon dioxide, special attention deserves the idea of ‘zeroemission’ technology based on boilers working in oxy-combustion technology. In the paper the results of analyses of the influence of changing two quantities, namely oxygen share in oxidant produced in the air separation unit, and oxygen share in oxidant supplied to the furnace chamber on the selected characteristics of a steam boiler including the degree of exhaust gas recirculation, boiler efficiency and adiabatic flame temperature, was examined. Due to the possibility of the integration of boiler model with carbon dioxide capture, separation and storage installation, the subject of the analysis was also to determine composition of the flue gas at the outlet of a moisture condensation installation. Required calculations were made using a model of a supercritical circulating fluidized bed boiler working in oxy-combustion technology, which was built in a commercial software and in-house codes.

  14. Rapid pyrolysis of wheat straw in a Bench-Scale circulating Fluidized-Bed downer reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ding, T. [State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing (China); Graduate School of Chinese Academy of Sciences, Beijing (China); Li, S.; Xie, J.; Song, W.; Yao, J.; Lin, W. [State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing (China)

    2012-12-15

    The effects of acid washing treatment on the pyrolysis product distribution and product properties were investigated in a bench-scale circulating fluidized-bed (CFB) downer reactor with wheat straw as feedstock. The acid treatment not only removes most of the inorganic species present in the biomass but also alters the distribution of the remaining organic constituents. It was found that the removal of the inorganic species increases the yield of liquid product and reduces char formation and gas yield. CO and CO{sub 2} are the dominant components in the gaseous product, accounting for over 90 %. The concentration of CO in the gaseous product increases after acid treatment, while the CO{sub 2} concentration decreases. The oxygen and water contents in the liquid product are decreased on acid treatment, leading to a relatively high heating value and viscosity. More volatiles can be found in the char derived from the acid-treated wheat straw than from the raw wheat straw. This may suggest that a longer residence time is needed for pyrolysis of the acid-treated wheat straw in order to obtain the maximal yield of volatile matter. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-30

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

  17. Electrochemical Recovery of Gold from Waste Electric and Electronic Equipment Using Circulating Particulate Bed Reactor (CPBE)

    Science.gov (United States)

    Ravinder, T.; Ali, U. F. M.; Ridwan, F. M.; Ibrahim, N.; Azmi, N. H.

    2017-06-01

    The utilization of electrochemical process recovery involving low reactant concentrations of metal requires electrodes with high mass transport rates and specific surface areas. This is essential to increase cross-sectional current densities whilst optimizing the capital and operating costs. Experimental results demonstrated that Circulating Particulate Bed Reactor (CPBE) is suitable for the recovery of low concentrations of gold from aqueous chloride solution containing {{AuCl}}4- and {{AuCl}}2- of less than 0.5 mol m-3(< 102 g m-3). Elemental gold was successfully obtained on 0.5-1 mm gr particles in an electrochemical reactor incorporating a cation- permeable membrane and operated in bath recycle mode. Depletion to concentration < 5 × 10-3 mol m-3 (< 1 g m-3) appeared to be mass transport controlled at an applied potential of +0.20 V (SCE), specific electrical energy consumption (SEEC) of ca. 800-1300 kWh h (tonne Au)-1 for cell voltages (U) of 2.0-3.0 V, and fractional current efficiencies of ca. 0.95. However, atomic absorption and UV spectrophotometry established that as the ([{{AuCl}}4-+[{{AuCl}}2-]) concentration decayed, the [{{AuCl}}4-]:[{{AuCl}}2-] molar ratio changed. A multi-step mechanism for reduction of {{AuCl}}4- ions explained this behavior in terms of changing overpotentials for {{AuCl}}4- and {{AuCl}}2- reduction as total dissolved gold concentration decreased. In addition, SEM images confirmed that adherent and coherent Au deposits were achieved with CPBE for Au deposition under mass transport control at 0.20 V (SCE).

  18. Influence of dissolved oxygen on the nitrification kinetics in a circulating bed biofilm reactor

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, R.; Melo, L.F. [University of Minho, Braga (Portugal). Dept. Bioengineering; Lazarova, V.; Manem, J. [Centre of International Research for Water and Environment (CIRSEE), Lyonnaise des Eaux, Le Pecq (France)

    1998-12-01

    The influence of dissolved oxygen concentration on the nitrification kinetics was studied in the circulating bed reactor (CBR). The study was partly performed at laboratory scale with synthetic water, and partly at pilot scale with secondary effluent as feed water. The nitrification kinetics of the laboratory CBR as a function of the oxygen concentration can be described according to the half order and zero order rate equations of the diffusion-reaction model applied to porous catalysts. When oxygen was the rate limiting substrate, the nitrification rate was close to a half order function of the oxygen concentration. The average oxygen diffusion coefficient estimated by fitting the diffusion-reaction model to the experimental results was around 66% of the respective value in water. The experimental results showed that either the ammonia or the oxygen concentration could be limiting for the nitrification kinetics. The latter occurred for an oxygen to ammonia concentration ratio below 1.5-2 gO{sub 2}/gN-NH{sub 4}{sup +} for both laboratory and pilot scale reactors. The volumetric oxygen mass transfer coefficient (k{sub L}a) determined in the laboratory scale reactor was 0.017 s{sup -1} for a superficial air velocity of 0.02 m s{sup -1}, and the one determined in the pilot scale reactor was 0.040 s{sup -1} for a superficial air velocity of 0.031 m s{sup -1}. The k{sub L}a for the pilot scale reactor did not change significantly after biofilm development, compared to the value measured without biofilm. (orig.) With 7 figs., 5 tabs., 24 refs.

  19. Co-firing coal and hospital waste in a circulating fluidized bed boiler

    International Nuclear Information System (INIS)

    Coulthard, E.J.; Korenberg, J.; Oswald, K.D.

    1991-01-01

    The Department of Energy - Morgantown Energy Technology Center and the Pennsylvania Energy Development Authority are co-funding a project which will demonstrate the reduction of infectious hospital waste to an environmentally safe disposable ash by cofiring the waste with coal in a circulating fluidized bed (CFB). The main objective of this paper is increased utilization of coal but the project also provides a solution to a problem which has grown rapidly and become very visible in recent years (e.g., hospital waste washed up on beaches). The application of CFB boilers in hospitals introduces an economical clean coal technology into a size range and market dominated by gas and oil combustion systems. The use of CFB represents the utilization of state-of-the-art technology for burning coal in an environmentally benign manner. SO 2 , NO x , CO and particulate emissions lower than the latest New Source Performance Standards have proven to be achievable in CFB combustion systems. By processing the infectious waste in a steam generation system which operates continuously, the problem of creating excessive gaseous emissions during repeated start-ups (as is the case with current incinerator technology) is avoided. The operating conditions with respect to residence time, temperature and turbulence that are inherent to a CFB combustion system, provide an excellent environment for complete combustion and destruction of potentially hazardous solid and gaseous emissions (e.g., dioxins). The limestone, which is injected into the combustion system to reduce SO 2 emissions, will also react with chlorine. Thus chlorine compound emissions and the corrosive nature of the flue gas are reduced. The work efforts to date indicate that infectious waste thermal processing in a coal-fired CFB is a technically and economically viable on-site disposal option

  20. CO-PRODUCTION OF HYDROGEN AND ELECTRICITY USING PRESSURIZED CIRCULATING FLUIDIZED BED GASIFICATION TECHNOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Zhen Fan

    2006-05-30

    Foster Wheeler has completed work under a U.S. Department of Energy cooperative agreement to develop a gasification equipment module that can serve as a building block for a variety of advanced, coal-fueled plants. When linked with other equipment blocks also under development, studies have shown that Foster Wheeler's gasification module can enable an electric generating plant to operate with an efficiency exceeding 60 percent (coal higher heating value basis) while producing near zero emissions of traditional stack gas pollutants. The heart of the equipment module is a pressurized circulating fluidized bed (PCFB) that is used to gasify the coal; it can operate with either air or oxygen and produces a coal-derived syngas without the formation of corrosive slag or sticky ash that can reduce plant availabilities. Rather than fuel a gas turbine for combined cycle power generation, the syngas can alternatively be processed to produce clean fuels and or chemicals. As a result, the study described herein was conducted to determine the performance and economics of using the syngas to produce hydrogen for sale to a nearby refinery in a hydrogen-electricity co-production plant setting. The plant is fueled with Pittsburgh No. 8 coal, produces 99.95 percent pure hydrogen at a rate of 260 tons per day and generates 255 MWe of power for sale. Based on an electricity sell price of $45/MWhr, the hydrogen has a 10-year levelized production cost of $6.75 per million Btu; this price is competitive with hydrogen produced by steam methane reforming at a natural gas price of $4/MMBtu. Hence, coal-fueled, PCFB gasifier-based plants appear to be a viable means for either high efficiency power generation or co-production of hydrogen and electricity. This report describes the PCFB gasifier-based plant, presents its performance and economics, and compares it to other coal-based and natural gas based hydrogen production technologies.

  1. CFD-DEM Simulation of Minimum Fluidisation Velocity in Two Phase Medium

    Directory of Open Access Journals (Sweden)

    H Khawaja

    2016-09-01

    Full Text Available In this work, CFD-DEM (computational fluid dynamics - discrete element method has been used to model the 2 phase flow composed of solid particle and gas in the fluidised bed. This technique uses the Eulerian and the Langrangian methods to solve fluid and particles respectively. Each particle is treated as a discrete entity whose motion is governed by Newton's laws of motion. The particle-particle and particle-wall interaction is modelled using the classical contact mechanics. The particles motion is coupled with the volume averaged equations of the fluid dynamics using drag law. In fluidised bed, particles start experiencing drag once the fluid is passing through. The solid particles response to it once drag experienced is just equal to the weight of the particles. At this moment pressure drop across the bed is just equal to the weight of particles divide by the cross-section area. This is the first regime of fluidization, also referred as ‘the regime of minimum fluidization’. In this study, phenomenon of minimum fluidization is studied using CFD-DEM simulation with 4 different sizes of particles 0.15 mm, 0.3 mm, 0.6 mm, and 1.2 mm diameters. The results are presented in the form of pressure drop across the bed with the fluid superficial velocity. The achieved results are found in good agreement with the experimental and theoretical data available in literature.

  2. Desulphurization in peat-fired circulating and bubbling fluidized bed boilers

    Energy Technology Data Exchange (ETDEWEB)

    Kouvo, P. [Imatran Voima Oy, Vantaa (Finland); Salmenoja, K. [Kvaerner Pulping Oy, Tampere (Finland)

    1997-12-31

    The new emission limit values for large combustion plants are under consideration both at the EU level and in Finland. Peat and wood are the only indigenous fuels of Finland. In 1995 appr. 8 % of electricity was produced with peat. The lower heating value of peat is around 10 MJ/kg. The moisture content varies between 35-55 % and sulphur content in dry solids between 0.15-0.35 %. The total peat power capacity of Finland in 1995 was 1400 MW. Because there was not enough information available about the desulphurization of the flue gases from peat-fired fluidized bed boilers, a group of Finnish companies and Ministry of Trade and Industry decided to carry out the full-scale desulphurisation study. In the project the desulphurization with limestone injection into the furnace of two types of peat-fired boilers were studied. The goal of the project was to investigate: what the technically and economically feasible emission level is by limestone injection in the fluidized bed combustion; how the limestone injection affects the other flue gas emissions and the fouling of the boiler and, what the economy of desulphurisation is. The tests were carried out at Kokkola and Kemi power plants in Finland. At Kokkola (108 MW{sub f}) circulating fluidized bed boiler, the emission limit of 200 mg/m{sup 3}n was leached at a Ca/S-molar ratio of appr. 10, with limestone containing 92 % of calcium carbonate, CaCO{sub 3}. At Kemi (267 MW{sub f}) bubbling fluidized bed boiler, the emission limit of 280 mg/m{sup 3}n with limestone containing appr. 95 % of CaCO{sub 3} was reached at a Ca/S-molar ratio of appr. 7.0. Emissions of NO{sub x}, N{sub 2}O, NH{sub 3} and dust after the ESP were not elevated due to the limestone feed. At the Kokkola power plant the NO{sub x} emissions varied from 300 to 400 mg/m{sup 3}n, and, at the Kemi power station the NO{sub x} emissions were around 200 mg/m{sup 3}n. The fouling of the Kemi boiler was found to be significant in the scheduled outage after the test

  3. Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

    Energy Technology Data Exchange (ETDEWEB)

    Wei-Ping Pan; Yan Cao; John Smith

    2008-05-31

    On February 14, 2002, President Bush announced the Clear Skies Initiative, a legislative proposal to control the emissions of nitrogen oxides (NO{sub x}), sulfur dioxide (SO{sub 2}), and mercury from power plants. In response to this initiative, the National Energy Technology Laboratory organized a Combustion Technology University Alliance and hosted a Solid Fuel Combustion Technology Alliance Workshop. The workshop identified multi-pollutant control; improved sorbents and catalysts; mercury monitoring and capture; and improved understanding of the underlying reaction chemistry occurring during combustion as the most pressing research needs related to controlling environmental emissions from fossil-fueled power plants. The Environmental Control Technology Laboratory will help meet these challenges and offer solutions for problems associated with emissions from fossil-fueled power plants. The goal of this project was to develop the capability and technology database needed to support municipal, regional, and national electric power generating facilities to improve the efficiency of operation and solve operational and environmental problems. In order to effectively provide the scientific data and the methodologies required to address these issues, the project included the following aspects: (1) Establishing an Environmental Control Technology Laboratory using a laboratory-scale, simulated fluidized-bed combustion (FBC) system; (2) Designing, constructing, and operating a bench-scale (0.6 MW{sub th}), circulating fluidized-bed combustion (CFBC) system as the main component of the Environmental Control Technology Laboratory; (3) Developing a combustion technology for co-firing municipal solid waste (MSW), agricultural waste, and refuse-derived fuel (RDF) with high sulfur coals; (4) Developing a control strategy for gaseous emissions, including NO{sub x}, SO{sub 2}, organic compounds, and heavy metals; and (5) Developing new mercury capturing sorbents and new

  4. Modelling of N2O Reduction in a Circulating Fluidized Bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars Erik; Dam-Johansen, Kim

    1996-01-01

    The addition of limestone for sulphur retention in Fluidized Bed Combustion (FBC) has been observed to influence the emission of N2O, and in many cases a lower emission was observed. The catalytic activity of a Danish limestone (Stevns Chalk) for decomposition of N2O in a laboratory fixed bed qua...

  5. Biomass Gasification in Internal Circulating Fluidized Beds: a Thermodynamic Predictive Tool

    Czech Academy of Sciences Publication Activity Database

    Miccio, F.; Svoboda, Karel; Schosger, J.-P.; Baxter, D.

    2008-01-01

    Roč. 25, č. 4 (2008), s. 721-726 ISSN 0256-1115 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidized bed * gasification * fluidized bed Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.830, year: 2008

  6. Circulating fluidized bed reformer-regenerator system for hydrogen production from methane. Paper no. IGEC-1-092

    International Nuclear Information System (INIS)

    Prasad, P.; Elnashaie, S.S.E.H.

    2005-01-01

    Steam reforming is presently the principal route for large-scale hydrogen production from natural gas. This paper proposes a novel concept of a reactor-regenerator type circulating fluidized bed (Prasad and Elnashaie, 2002) for efficient production of hydrogen. Carbon is optimally allowed to form on the catalyst in the reactor section through methane cracking and Boudouard coking reactions, and the deactivated catalyst is regenerated in the regenerator by burning off the carbon. This concept of carbon formation and burning cannot be used in a fixed bed configuration but is possible in the proposed novel Circulating Fluidized Bed (CFB) configuration, which employs a reactor-regenerator type of configuration. Allowing both carbon formation and steam reforming to occur simultaneously by introducing steam as part of the feed, gives more than 3 moles hydrogen per mole of methane at almost zero energy consumption. The steam can be fed as water at room temperature, and the hot catalyst returning from the regenerator can be used to vaporize it into steam. This route is the most efficient from both hydrogen yield and energy consumption points of view. This CFB configuration exhibits the bifurcation behavior and the present paper reports an investigation of its static bifurcation characteristics through a rigorous mathematical model. (author)

  7. Large-diameter boring of rock bed by a reveres circulation drill; Ribasu sakyureshon doriru ni yoru daikokei ganban sakko

    Energy Technology Data Exchange (ETDEWEB)

    Sakae, S.; Torii, K. [Kajima Corp., Tokyo (Japan); Hoshino, S.; Motoyama, M.

    1995-09-25

    The Itojima Large Bridge is a road bridge of 675 m in the total length connecting together the Nagashima Island and the Itojima Island in the northwest district of Kagoshima Prefecture, having a central span of 260 m and comprising a 5-span-continuous PC cable stayed bridges and PC box girder bridges. The foundation of this bridge employs a multi-pillar type pile structure. The piling work was started in July, 1991 by a hole inset method in a severe working environment where the depth of water is 20 m, the range of the tides is 4 m, the speed of tidal current is 2 kt, the rock bed structure is complicated and the steep seabed is steeply inclined. This report describes the results of the execution of the reverse circulation drilling, which has a high general versatility in rock bed boring, using self-lifting barges and large working boats during the rock bed boring for the foundation piling for the construction of the Itojima Large Bridge. The report, especially, also introduces the details of the work that casing pipes were driven into a stable rock bed by a vibrojet method for the measure against the collapse of a bore wall which occurred during the boring work. 24 figs., 14 tabs.

  8. Numerical simulation of the gas-solid flow in a square circulating fluidized bed with secondary air injection

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhengyang [Harbin Institute of Technology, Harbin (China). Post-doctor Station of Civil Engineering; Harbin Institute of Technology, Harbin (China). Combustion Engineering Research Inst.; Sun, Shaozeng; Zhao, Ningbo; Wu, Shaohua [Harbin Institute of Technology, Harbin (China). Combustion Engineering Research Inst.; Tan, Yufei [Harbin Institute of Technology, Harbin (China). School of Municipal and Environmental Engineering

    2013-07-01

    The dynamic behavior of gas-solid flow in an experimental square circulating fluidized bed setup (0.25 m x 0.25 m x 6.07 m) is predicted with numerical simulation based on the theory of Euler-Euler gas-solid two-phase flow and the kinetic theory of granular flows. The simulation includes the operation cases with secondary injection and without air-staging. The pressure drop profile, local solids concentration and particle velocity was compared with experimental results. Both simulation and experimental results show that solids concentration increases significantly below the secondary air injection ports when air-staging is adopted. Furthermore, the flow asymmetry in the solid entrance region of the bed was investigated based on the particle concentration/velocity profile. The simulation results are in agreement with the experimental results qualitatively.

  9. Experimental study of the mechanisms of CO2 capture by calcium cycle under circulating fluidized bed conditions

    International Nuclear Information System (INIS)

    Hoteit, A.

    2006-06-01

    The work undertaken in this Thesis in partnership with department R and D of ALSTOM Power Boilers, CEMEX and the ADEME, relates to the experimental study of various phenomena associated to CO 2 capture under circulating fluidized bed conditions. The size of particles, temperature and the CO 2 concentration have an influence on the limestone calcination reaction. The reaction of carbonation of lime is not total. During successive cycles of calcination/carbonation, the rate of carbonation obtained with hydrated lime is increasingly higher than that obtained with the lime. Under continuously reducing conditions, the decomposition of sulphates present in the bed ashes is not total. This decomposition is total under reduction/oxidation cycles. A modeling of calcination allowed to determine the intrinsic kinetic constants of calcination and carbonation. (author)

  10. Three-stage steady-state model for biomass gasification in a dual circulating fluidized-bed

    International Nuclear Information System (INIS)

    Nguyen, Thanh D.B.; Ngo, Son Ich; Lim, Young-Il; Lee, Jeong Woo; Lee, Uen-Do; Song, Byung-Ho

    2012-01-01

    Highlights: ► Steam gasification of woodchips is examined in dual circulating fluidized-bed (DFB). ► We develop a three-stage model (TSM) for process performance evaluation. ► Effect of gasification temperature and steam to fuel ratio is investigated. ► Several effective operating conditions are found by parametric study. - Abstract: A three-stage steady state model (TSM) was developed for biomass steam gasification in a dual circulating fluidized-bed (DFB) to calculate the composition of producer gas, carbon conversion, heat recovery, cost efficiency, and heat demand needed for the endothermic gasification reactions. The model was divided into three stages including biomass pyrolysis, char–gas reactions, and gas–phase reaction. At each stage, an empirical equation was estimated from experimental data. It was assumed that both unconverted char and additional fuel were completely combusted at 950 °C in the combustor (riser) and the heat required for gasification reactions was provided by the bed material (silica sand). The model was validated with experimental data taken from the literature. The parametric study of the gasification temperature (T) and the steam to fuel ratio (γ) was then carried out to evaluate performance criteria of a 1.8 MW DFB gasifier using woodchips as a feedstock for the electric power generation. Effective operating conditions of the DFB gasifier were proposed by means of the contour of the solid circulation ratio, the heat recovery, the additional fuel ratio and the cost efficiency with respect to T and γ.

  11. Bottom ash from fluidising bed boilers as filler material in district heating pipe culverts. Chemical and geotechnical characterisation; Pannsand som kringfyllnadsmaterial foer fjaerrvaermeroergravar. Kemisk och geoteknisk karaktaerisering av fluidbaeddsand

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Roger; Rogbeck, Jan; Suer, Pascal

    2004-01-01

    Bottom ashes from fluid bed boilers have been characterised, both geotechnically and chemically, in order to investigate the possibility to use them as filler material in district heating pipe culverts. Bottom ashes from both biofuel boilers and waste boilers are represented in this project. The companies which ashes have been characterised are Sundsvall Energi AB, Sydkraft OestVaerme AB, Sydkraft MaelarVaerme AB, Eskilstuna Miljoe och Energi, Stora Enso Fors, Soederenergi and Fortum Vaerme. A total of ten ashes have been analysed where three ashes originates from Sundsvall Energi AB, two from Sydkraft OestVaerme AB and one from the each of the remaining companies. The chemical analyses have been performed both on fresh ashes and on ashes aged for three months. The geotechnical analyses performed are grain size distribution, packing abilities and permeability. Chemical analyses performed are total content, available content, leaching tests (leaching both by shaking method and column procedure) and organic analyses (PAH, EOX, TOC, dioxin and fenol). The geotechnical analyses show that the ashes fulfils the demands that are put on the filler material used in district heating pipe culverts. When using the ashes in applications, light compaction should be performed due to the risk of crushing the material which may cause an increased amount of fine material. The leachability of fine material is larger than for coarse material. The ashes are relatively insensitive to precipitation. Bio fuel based bottom ashes have a lower content of environmental affecting substances than waste fuel based ashes. This is also shown in the leaching analyses. The leaching water from fresh ashes contains a higher concentration of leachable components than aged ashes. When aged the pH in the ashes decreases due to carbon uptake and hydration and this makes metals as Pb, Cu, Cr and Zn less mobile. On the other hand, an increase in leachability of Sb, Mo and SO{sub 4} is shown when the ashes

  12. Fluid-bed methane proposed

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    The first full scale plant for the production of methane from organic waste could be built in the next few years believes M.J. Nyns of the University of Louvain, Belgium, utilizing either expanded bed or fluidised bed systems, with more than one stage, in a continuous flow arrangement. Up to 8.0 m cubed gas/m cubed digester/day could be produced with residence times reduced to 34 hours.

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

    Science.gov (United States)

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

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

  14. Final Environmental Impact Statement for the JEA Circulating Fluidized Bed Combustor Project

    Energy Technology Data Exchange (ETDEWEB)

    N/A

    2000-06-30

    This EIS assesses environmental issues associated with constructing and demonstrating a project that would be cost-shared by DOE and JEA (formerly the Jacksonville Electric Authority) under the Clean Coal Technology Program. The project would demonstrate circulating fluidized bed (CFB) combustion technology at JEA's existing Northside Generating Station in Jacksonville, Florida, about 9 miles northeast of the downtown area of Jacksonville. The new CFB combustor would use coal and petroleum coke to generate nearly 300 MW of electricity by repowering the existing Unit 2 steam turbine, a 297.5-MW unit that has been out of service since 1983. The proposed project is expected to demonstrate emission levels of sulfur dioxide (SO{sub 2}), oxides of nitrogen (NO{sub x}), and particulate matter that would be lower than Clean Air Act limits while at the same time producing power more efficiently and at less cost than conventional coal utilization technologies. At their own risk, JEA has begun initial construction activities without DOE funding. Construction would take approximately two years and, consistent with the original JEA schedule, would be completed in December 2001. Demonstration of the proposed project would be conducted during a 2-year period from March 2002 until March 2004. In addition, JEA plans to repower the currently operating Unit 1 steam turbine about 6 to 12 months after the Unit 2 repowering without cost-shared funding from DOE. Although the proposed project consists of only the Unit 2 repowering, this EIS analyzes the Unit 1 repowering as a related action. The EIS also considers three reasonably foreseeable scenarios that could result from the no-action alternative in which DOE would not provide cost-shared funding for the proposed project. The proposed action, in which DOE would provide cost-shared finding for the proposed project, is DOE's preferred alternative. The EIS evaluates the principal environmental issues, including air quality

  15. 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.

  16. Predictive models of circulating fluidized bed combustors: SO{sub 2} sorption in the CFB loop. Fourteenth technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Gidaspow, D.; Therdthianwong, A. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering

    1993-02-01

    The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Sorption of S0{sub 2} with calcined limestone was studied in a PYROFLOW type CFB loop at conditions approximating those found in a CFB combustor. Initially the CFB loop contained 150 micron CaO particles of a density of 3.3 g/cm{sup 3} and air at 1143{degrees}K and 3.25 atm. Atzero time, air containing 600 ppm SO{sub 2}, was introduced into the riser bottom at 1143{degrees}K. The effect of gas velocity, sorbent inventory and inlet pressure on the sorption of SO{sub 2}, were studied isothermally by running our hydrodynamic code with the S0{sub 2} sorption conservation of species equation. At a velocity of 5m/sec., reported to be a typical velocity by PYROPOWER, there is reasonably good S0{sub 2} removal. At 10 m/sec the S0{sub 2} removal is poor. The best SO{sub 2}, removal is for a velocity of 5 m/s and a high bed inventory, initial bed height, H = 9m. Most of the S0{sub 2} is removed in the first two meters of the reactor. However, the S0{sub 2} removal is not complete at the bed outlet. This is due to mixing. At the left wall of the reactor (wall opposite the solids inlet) the S0{sub 2} removal was poor due to gas bypassing caused by the asymmetrical solids inlet. Simulation of the PYROPOWER loop with a symmetrical inlet gave us an order of magnitude improvement over the conventional PYROPOWER system. These results demonstrate the practical utility of the predictive model that we have developed over the last three years.

  17. Chemical Processes Related to Combustion in Fluidised Bed

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-12-01

    This report covers work that has been carried out in the combustion chemistry group at the Dept. of Environmental Inorganic Chemistry, Chalmers, within the STEM project 12859-1, during the period 2000-07-01 to 2002-06-30. The work was comprised of the following parts: Sulphur chemistry under pressurised and atmospheric conditions; Gas/solid reactions related to sintering and fouling; Chemistry of volatile metals in combustion; Ash leaching properties; Theoretical modelling of the interactions between ions in a solution and mineral surfaces; Some related issues and co-operations with other departments. The work on sulphur chemistry has been a central issue in our group and it has now been finalised with a PhD thesis discussing some aspects of the sulphation of limestone under pressurised conditions. The influence of a number of parameters on the sulphation efficiency was investigated and compared with similar studies under atmospheric conditions. In a special study it was shown that the influence of alternating calcining - non-calcining conditions on the conversion was substantial. In addition, the oxidation of CaS and sulphided limestone was studied and a regeneration method for the sulphide sorbent was proposed. In the project part concerning gas - solid reactions that are relevant to sintering and fouling, the application of an on-line measurement technique for the study of alkali metal capture by kaolin or other sorbents is described. A new reactor set-up has been constructed and the initial results from this set up are promising. The chemistry of cadmium in combustion of MSW and biomass is the object of a PhD project. This work has been concentrated on the task of identifying Cd-compounds in fly ash samples. It has now come to a point where enough data has been collected to make it possible to give an indication about the Cd speciation in some ash types. In MSW ash particles, cadmium seem to occur mainly as chloride, oxide and sulphate. The work will continue with evaluation of other biomass ash particles and, as an extension, the speciation of Cu and Zn will be studied as well. Ash fractions from combustion of MSW in a BFB boiler have been investigated regarding composition and leaching properties, i.e. environmental impact risks. The release of salts from the cyclone ash fraction can be minimised by the application of a simple washing process, thus securing that the leaching of soluble substances stays within the regulative limits. The MSW ash - water systems contain some interesting chemical issues, such as the interactions between Cr(VI) and reducing substances like Al-metal. The understanding of such chemical processes is important since it gives a possibility to predict effects of a change in ash composition. An even more detailed understanding of interactions between a solution containing ions and particle surfaces can be gained by theoretical modelling. In this project (and with additional unding from Aangpannefoereningens Forskningsstiftelse) a theoretical description of ion-ion interactions and the solid-liquid-interface has been developed. Some related issues are also included in this report. The publication of a paper on the reactions of ammonia in the presence of a calcining limestone surface is one of them. A review paper on the influence of combustion conditions on the properties of fly ash and its applicability as a cement replacement in concrete is another. The licentiate thesis describing the sampling and measurement of Cd in flue gas is also included since it was finalised during the present period. A co-operation project involving the Geology Dept. at Goeteborg Univ. and our group is briefly discussed. This project concerns the utilisation of granules produced from wood ash and dolomite as nutrient source for forest soil. Finally, the plans for our flue gas simulator facility are discussed.

  18. 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...

  19. Sustainable nitrification in fluidised bed reactor with immobilised ...

    African Journals Online (AJOL)

    2012-02-01

    Feb 1, 2012 ... polyacrylamide, polystyrene, polyurethane and polyethylene glycol, have been .... and photographed under ultraviolet light. The representative ..... ited NOB population in immobilised pellets, the degradation of NH4. +-N by ...

  20. Sustainable nitrification in fluidised bed reactor with immobilised ...

    African Journals Online (AJOL)

    TOC concentration above 800 mg·ℓ-1 was not able to cause the inhibition of the heterotrophs over the nitrifiers. PCR-DGGE results indicated the presence of Nitrosomonas (ammonia-oxidising bacteria) and Nitrobacter (nitrite-oxidising bacteria) in the immobilised pellets. Keywords: bioimmobilisation, ammonium, partial ...

  1. Application of Scaling-Law and CFD Modeling to Hydrodynamics of Circulating Biomass Fluidized Bed Gasifier

    Directory of Open Access Journals (Sweden)

    Mazda Biglari

    2016-06-01

    Full Text Available Two modeling approaches, the scaling-law and CFD (Computational Fluid Dynamics approaches, are presented in this paper. To save on experimental cost of the pilot plant, the scaling-law approach as a low-computational-cost method was adopted and a small scale column operating under ambient temperature and pressure was built. A series of laboratory tests and computer simulations were carried out to evaluate the hydrodynamic characteristics of a pilot fluidized-bed biomass gasifier. In the small scale column solids were fluidized. The pressure and other hydrodynamic properties were monitored for the validation of the scaling-law application. In addition to the scaling-law modeling method, the CFD approach was presented to simulate the gas-particle system in the small column. 2D CFD models were developed to simulate the hydrodynamic regime. The simulation results were validated with the experimental data from the small column. It was proved that the CFD model was able to accurately predict the hydrodynamics of the small column. The outcomes of this research present both the scaling law with the lower computational cost and the CFD modeling as a more robust method to suit various needs for the design of fluidized-bed gasifiers.

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

    Science.gov (United States)

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

    2015-12-01

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

  3. Effects of the updated national emission regulation in China on circulating fluidized bed boilers and the solutions to meet them.

    Science.gov (United States)

    Li, Jingji; Yang, Hairui; Wu, Yuxin; Lv, Junfu; Yue, Guangxi

    2013-06-18

    The advantage of circulating fluidized bed (CFB) boilers in China is their ability to utilize low rank coal with low cost emission control. However, the new National Emission Regulation (NER) issued in early 2012 brings much more stringent challenges on the CFB industries, which also causes much attention from other countries. Based on the principle of a CFB boiler and previous operating experience, it is possible for the CFB boilers to meet the new NER and maintain the advantage of low cost emission control, while, more influences should be considered in their design and operation. To meet the requirement of the new NER, the fly ash collector should adopt a bag house or combination of electrostatic precipitator and bag filter to ensure dust emissions of less than 30 mg · Nm(-3). For SO2 emission control, the bed temperature should be strictly lower than 900 °C to maintain high reactivity and pores. The limestone particle size distribution should be ranged within a special scope to optimize the residence time and gas-solid reaction. At the same time, the injecting point should be optimized to ensure fast contact of lime with oxygen. In such conditions, the desulfurization efficiency could be increased more than 90%. For lower sulfur content fuels (emissions lower than that of the new NER, 100 mg · Nm(-3). For fuels with sulfur content higher than 1.5%, some simplified systems for flue gas desulfurization, such as flash dryer absorber (FDA), are needed. And the NOx emissions of a CFB can be controlled to less than 100 mg · Nm(-3) without any equipment at a bed temperature lower than 900 °C for fuels with low volatiles content (emission of CFB is very low for the new NER due to its innate property.

  4. Fluidized bed gasification of selected South African coals

    CSIR Research Space (South Africa)

    Engelbrecht, AD

    2010-05-01

    Full Text Available that due to the good heat and mass transfer properties of fluidised beds, coal with ash contents up to 70% can be utilised. The CSIR’s research and development work resulted in the installation of five bubbling fluidised bed combustors (BFBCs) between... 1989 and 1999. Other companies, such as Babcock and Scientific Design, also installed a number of BFBC plants during this time. It was realised during the development of BFBC technology that due to the low lateral dispersion coefficient of coal...

  5. Thermal–hydraulic calculation and analysis of a 600 MW supercritical circulating fluidized bed boiler with annular furnace

    International Nuclear Information System (INIS)

    Wang, Long; Yang, Dong; Shen, Zhi; Mao, Kaiyuan; Long, Jun

    2016-01-01

    Highlights: • Non-linear model of supercritical CFB boiler with annular furnace is developed. • Many empirical correlations are used to solve the model. • The thermal–hydraulic characteristics of boiler are analyzed. • The results show that the design of the annular furnace is reasonable. - Abstract: The development of supercritical Circulating Fluidized Bed (CFB) boiler has great economic and environmental value. An entirely new annular furnace structure with outer and inner ring sidewalls for supercritical CFB boiler has been put forward by Institute of Engineering Thermophysics (IET), Chinese Academy of Sciences and Dongfang Boiler Group Co., Ltd. (DBC). Its outer and inner ring furnace structure makes more water walls arranged and reduces furnace height availably. In addition, compared with other additional evaporating heating surface structures such as mid-partition and water-cooled panels, the integrative structure can effectively avoid the bed-inventory overturn and improve the penetrability of secondary air. The conditions of the 600 MW supercritical CFB boiler including capability, pressure and mass flux are harsh. In order to insure the safety of boiler operation, it is very necessary to analyze the thermal–hydraulic characteristics of water-wall system. The water-wall system with complicated pipe arrangement is regarded as a network consisting of series-parallel circuits, pressure nodes and linking circuits, which represent vertical water-wall tubes, different headers and linking tubes, respectively. Based on the mass, momentum and energy conservation, a mathematical model is built, which consists of some simultaneous nonlinear equations. The mass flux in circuits, pressure drop between headers, outer vapor temperature of water-wall system and metal temperature data of tubes at the boiler maximum continuous rating (BMCR), 75% BMCR and 30% BMCR loads are obtained by solving the mathematical model. The results show that the vertical water

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  7. Bifurcation behavior during the hydrogen production in two compatible configurations of a novel circulating fluidized bed membrane reformer

    International Nuclear Information System (INIS)

    Chen, Z.; Elnashaie, S.S.

    2004-01-01

    'Full text:' Multiplicity of steady states (Static Bifurcation Behavior, SBB) in a novel Circulating Fluidized Bed (CFB) membrane reformer for the efficient production of hydrogen by steam reforming of heptane (model component of heavy hydrocarbons and renewable bio-oils) is investigated. The present paper highlights the practical implications of this phenomenon on the behavior of this novel reformer with special focusing on hydrogen production. Two configurations are considered and compared. One is with the catalyst regeneration before the gas-solid separation and the other one is with the catalyst regeneration after the gas-solid separation. Multiplicity of the steady states prevails over a number of design and operating parameters with important impact on the reformer performance. The basis of process evaluation is focused on the net hydrogen production. The dependence of the behavior of this autothermal CFB is shown to be quite complex and defy the simple logic of non-autothermal processes. The unit can be a very efficient hydrogen producer provided its bifurcation behavior is well understood and correctly exploited. (author)

  8. Investigation of gas–solids flow in a circulating fluidized bed using 3D electrical capacitance tomography

    International Nuclear Information System (INIS)

    Mao, Mingxu; Ye, Jiamin; Wang, Haigang; Yang, Wuqiang

    2016-01-01

    The hydrodynamics of gas–solids flow in the bottom of a circulating fluidized bed (CFB) are complicated. Three-dimensional (3D) electrical capacitance tomography (ECT) has been used to investigate the hydrodynamics in risers of different shapes. Four different ECT sensors with 12 electrodes each are designed according to the dimension of risers, including two circular ECT sensors, a square ECT sensor and a rectangular ECT sensor. The electrodes are evenly arranged in three planes to obtain capacitance in different heights and to reconstruct the 3D images by linear back projection (LBP) algorithm. Experiments were carried out on the four risers using sands as the solids material. The capacitance and differential pressure are measured under the gas superficial velocity from 0.6 m s −1 to 3.0 m s −1 with a step of 0.2 m s −1 . The flow regime is investigated according to the solids concentration and differential pressure. The dynamic property of bubbling flows is analyzed theoretically and the performance of the 3D ECT sensors is evaluated. The experimental results show that 3D ECT can be used in the CFB with different risers to predict the hydrodynamics of gas–solids bubbling flows. (paper)

  9. Experimental findings on thermal use of residues and biofuels in circulating fluidized bed combustion systems; Experimentelle Ergebnisse zur thermischen Nutzung von Rest- und Biobrennstoffen in zirkulierenden Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W.; Brunne, T.; Girndt, H. [Technische Univ. Dresden (Germany); Albrecht, J. [Lurgi Lentjes Babcock, Frankfurt am Main (Germany); Youssef, M. [Minia Univ. (Egypt)

    1996-12-31

    The energy Engineering Institute of Dresden Technical University investigated the combustion and emission characteristics of a number of combustion systems, including a circulating fluidized bed system with a capacity of 0.3 MW{sub th}. Egypt`s sugar cane industry produces large volumes of bagasse. The conbustion and emission characteristics of this biofuel in a circulating fludized bed combustion systems were investigated in a joint research project of the University of Minia and Dresden Technical University. (orig.) [Deutsch] Am Institut fuer Energietechnik der TU Dresden wird das Verbrennungs- und Emissionsverhalten verschiedenster Brennstoffe in unterschiedlichen Feuerungssystemen untersucht. Neben anderen Pilotanlagen steht eine zirkulierende Wirbelschichtfeuerung (ZWFS) mit einer Leistung von 0.3 MW{sub th} zur Verfuegung. In der Zuckerrohrindustrie Aegyptens fallen grosse Mengen von Bagasse an. In einer gemeinsamen Forschungsarbeit zwischen der Universitaet Minia und der TU Dresden sollte das Verbrennungs- und Emissionsverhalten dieses Biobrennstoffes in einer ZWSF untersucht werden. (orig)

  10. Experimental findings on thermal use of residues and biofuels in circulating fluidized bed combustion systems; Experimentelle Ergebnisse zur thermischen Nutzung von Rest- und Biobrennstoffen in zirkulierenden Wirbelschichtfeuerungen

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W; Brunne, T; Girndt, H [Technische Univ. Dresden (Germany); Albrecht, J [Lurgi Lentjes Babcock, Frankfurt am Main (Germany); Youssef, M [Minia Univ. (Egypt)

    1997-12-31

    The energy Engineering Institute of Dresden Technical University investigated the combustion and emission characteristics of a number of combustion systems, including a circulating fluidized bed system with a capacity of 0.3 MW{sub th}. Egypt`s sugar cane industry produces large volumes of bagasse. The conbustion and emission characteristics of this biofuel in a circulating fludized bed combustion systems were investigated in a joint research project of the University of Minia and Dresden Technical University. (orig.) [Deutsch] Am Institut fuer Energietechnik der TU Dresden wird das Verbrennungs- und Emissionsverhalten verschiedenster Brennstoffe in unterschiedlichen Feuerungssystemen untersucht. Neben anderen Pilotanlagen steht eine zirkulierende Wirbelschichtfeuerung (ZWFS) mit einer Leistung von 0.3 MW{sub th} zur Verfuegung. In der Zuckerrohrindustrie Aegyptens fallen grosse Mengen von Bagasse an. In einer gemeinsamen Forschungsarbeit zwischen der Universitaet Minia und der TU Dresden sollte das Verbrennungs- und Emissionsverhalten dieses Biobrennstoffes in einer ZWSF untersucht werden. (orig)

  11. Experimental study on fuel oil combustion in circulating fluidized bed; Estudio experimental sobre la combustion de combustoleo en lecho fluidizado circulante

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Rangel, Ricardo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    The Instituto de Investigaciones Electricas (IIE) developed a circulating fluidized bed combustor of 0.5 thermal MW unique in its type in Latin America. The Bachelor`s thesis entitled ``Experimental Study on Fuel Oil Combustion in Circulating Fluidized Bed`` was performed operating this combustor with the purpose of determining the feasibility of burning heavy fuel oil in a stable and sustained form, as well as the effect of the addition of calcium carbonate to the combustor. The results of the experimental trials showed heavy fuel oil can be burned in a circulating fluidized bed, with low sulfur dioxide emissions. During the conduction of the experiments a sulfur retention of 43% was achieved with a Ca/S relationship of 4.5. [Espanol] El Instituto de Investigaciones Electricas (IIE) desarrollo un combustor de lecho fluidizado circulante de 0.5 MW termicos de potencia, unico en su tipo en Latinoamerica. La tesis de licenciatura titulada Estudio Experimental sobre la Combustion de Combustoleo en Lecho Fluidizado Circulante se realizo operando dicho combustor, con el proposito de determinar la factibilidad de quemar combustoleo pesado en forma estable y autosostenida, asi como la influencia que tiene la adicion de carbonato de calcio al lecho. Los resultados de los ensayos experimentales mostraron que se puede quemar combustoleo pesado en un lecho fluidizado circulante, con bajas emisiones de bioxido de azufre. Durante la experimentacion se logro una retencion de azufre del 43%, con una relacion Ca/S de 4.5.

  12. Experimental study on fuel oil combustion in circulating fluidized bed; Estudio experimental sobre la combustion de combustoleo en lecho fluidizado circulante

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Rangel, Ricardo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1997-12-31

    The Instituto de Investigaciones Electricas (IIE) developed a circulating fluidized bed combustor of 0.5 thermal MW unique in its type in Latin America. The Bachelor`s thesis entitled ``Experimental Study on Fuel Oil Combustion in Circulating Fluidized Bed`` was performed operating this combustor with the purpose of determining the feasibility of burning heavy fuel oil in a stable and sustained form, as well as the effect of the addition of calcium carbonate to the combustor. The results of the experimental trials showed heavy fuel oil can be burned in a circulating fluidized bed, with low sulfur dioxide emissions. During the conduction of the experiments a sulfur retention of 43% was achieved with a Ca/S relationship of 4.5. [Espanol] El Instituto de Investigaciones Electricas (IIE) desarrollo un combustor de lecho fluidizado circulante de 0.5 MW termicos de potencia, unico en su tipo en Latinoamerica. La tesis de licenciatura titulada Estudio Experimental sobre la Combustion de Combustoleo en Lecho Fluidizado Circulante se realizo operando dicho combustor, con el proposito de determinar la factibilidad de quemar combustoleo pesado en forma estable y autosostenida, asi como la influencia que tiene la adicion de carbonato de calcio al lecho. Los resultados de los ensayos experimentales mostraron que se puede quemar combustoleo pesado en un lecho fluidizado circulante, con bajas emisiones de bioxido de azufre. Durante la experimentacion se logro una retencion de azufre del 43%, con una relacion Ca/S de 4.5.

  13. Comparison of ANN (MLP), ANFIS, SVM, and RF models for the online classification of heating value of burning municipal solid waste in circulating fluidized bed incinerators.

    Science.gov (United States)

    You, Haihui; Ma, Zengyi; Tang, Yijun; Wang, Yuelan; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa; Huang, Qunxing

    2017-10-01

    The heating values, particularly lower heating values of burning municipal solid waste are critically important parameters in operating circulating fluidized bed incineration systems. However, the heating values change widely and frequently, while there is no reliable real-time instrument to measure heating values in the process of incinerating municipal solid waste. A rapid, cost-effective, and comparative methodology was proposed to evaluate the heating values of burning MSW online based on prior knowledge, expert experience, and data-mining techniques. First, selecting the input variables of the model by analyzing the operational mechanism of circulating fluidized bed incinerators, and the corresponding heating value was classified into one of nine fuzzy expressions according to expert advice. Development of prediction models by employing four different nonlinear models was undertaken, including a multilayer perceptron neural network, a support vector machine, an adaptive neuro-fuzzy inference system, and a random forest; a series of optimization schemes were implemented simultaneously in order to improve the performance of each model. Finally, a comprehensive comparison study was carried out to evaluate the performance of the models. Results indicate that the adaptive neuro-fuzzy inference system model outperforms the other three models, with the random forest model performing second-best, and the multilayer perceptron model performing at the worst level. A model with sufficient accuracy would contribute adequately to the control of circulating fluidized bed incinerator operation and provide reliable heating value signals for an automatic combustion control system. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-15

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

  15. Co-firing option of palm shell waste and Malaysian coal blends in a circulating fluidized bed

    International Nuclear Information System (INIS)

    Ahmad Hussain; Farid Nasir Ani

    2010-01-01

    Palm oil shell waste is one of the main agriculture wastes in Malaysia. In order to utilize these wastes efficiently, pyrolysis of oil-palm shell waste was first carried out using Thermogravimetric analysis (TGA). The effects of heating rate on the pyrolytic properties were investigated to evaluate its suitability for co-firing. The TGA analyses of oil palm shell waste and Malaysian coal blends suggests that there is an obvious lateral shift in the thermo grams for different heating rate. Kinetics calculations were also done using integral method. For palm shell waste powder it was found that the activation energies ranged from 112-119 kJ/mole and for the Mukah coal blends it ranged from 93.3 -100.8 kJ/mole. Combustion studies for palm shell wastes and coal blends were done in a hot circulating fluidized-bed (CFB) test rig. This is the first practical experience of using this type of rig in Malaysia. The temperature dependence on the combustion and emission behaviour were identified. The effects of variation of primary air and feed rate have also been analyzed and their influence on emissions has been established. The combustion studies of palm shell wastes were done and it was found that the emission of NO x ranged from 20-164 ppm while the CO emissions were high for some operating conditions. For the co-firing studies, the NO x and CO deceased with the percentage increase in the blending ratio of coal with palm shell waste.. The optimum blending ratio was found to be in a ratio of 40 percent coal and 60 percent Mukah coal. It was also found that Mukah coal show agglomeration behaviour with when it is blended in 80% ratio. (author)

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  17. Climate effect of an integrated wheat production and bioenergy system with Low Temperature Circulating Fluidized Bed gasifier

    International Nuclear Information System (INIS)

    Sigurjonsson, Hafthor Ægir; Elmegaard, Brian; Clausen, Lasse Røngaard; Ahrenfeldt, Jesper

    2015-01-01

    Highlights: • Wheat straw removal from agricultural system has considerable GWP effect. • Changing the carbon conv. in the gasifier to 0.8–0.86 mitigates those effects. • Considerable difference is between sequestration potential of straw and biochar. • Lowering the carbon conversion improves GWP, but depends on subst. technology. - Abstract: When removing biomass residues from the agriculture for bioenergy utilization, the nutrients and carbon stored within these “residual resources” are removed as-well. To mitigate these issues the energy industry must try to conserve and not destroy the nutrients. The paper analyses a novel integration between the agricultural system and the energy system through the Low Temperature Circulating Fluidized Bed (LT-CFB) gasifier from the perspective of wheat grain production and electricity generation using wheat straw, where the effects of removing the straw from the agricultural system are assessed along with the effects of recycling the nutrients and carbon back to the agricultural system. The methods used to assess the integration was Life Cycle Assessment (LCA) with IPCC’s 2013 100 year global warming potential (GWP) as impact assessment method. The boundary was set from cradle to gate with two different functional units, kg grain and kW h electricity produced in Zealand, Denmark. Two cases were used in the analysis: 1. nutrient balances are regulated by mineral fertilization and 2. the nutrient balances are regulated by yield. The analysis compare three scenarios of gasifier operation based on carbon conversion to two references, no straw removal and straw combustion. The results show that the climate effect of removing the straws are mitigated by the carbon soil sequestration with biochar, and electricity and district heat substitution. Maximum biochar production outperforms maximum heat and power generation for most substituted electricity and district heating scenarios. Irrespective of the substituted

  18. Selective phenol methylation to 2,6-dimethylphenol in a fluidized bed of iron-chromium mixed oxide catalyst with o-cresol circulation.

    Science.gov (United States)

    Zukowski, Witold; Berkowicz, Gabriela; Baron, Jerzy; Kandefer, Stanisław; Jamanek, Dariusz; Szarlik, Stefan; Wielgosz, Zbigniew; Zielecka, Maria

    2014-01-01

    2,6-dimethylphenol (2,6-DMP) is a product of phenol methylation, especially important for the plastics industry. The process of phenol methylation in the gas phase is strongly exothermic. In order to ensure good temperature equalization in the catalyst bed, the process was carried out using a catalyst in the form of a fluidized bed - in particular, the commercial iron-chromium catalyst TZC-3/1. Synthesis of 2,6-dimethylphenol from phenol and methanol in fluidized bed of iron-chromium catalyst was carried out and the fluidization of the catalyst was examined. Stable state of fluidized bed of iron-chromium catalyst was achieved. The measured velocities allowed to determine the minimum flow of reactants, ensuring introduction of the catalyst bed in the reactor into the state of fluidization. Due to a high content of o-cresol in products of 2,6-dimethylphenol synthesis, circulation in the technological node was proposed. A series of syntheses with variable amount of o-cresol in the feedstock allowed to determine the parameters of stationary states. A stable work of technological node with o-cresol circulation is possible in the temperature range of350-380°C, and o-cresolin/phenolin molar ratio of more than 0.48. Synthesis of 2,6-DMP over the iron-chromium catalyst is characterized by more than 90% degree of phenol conversion. Moreover, the O-alkylation did not occur (which was confirmed by GC-MS analysis). By applying o-cresol circulation in the 2,6-DMP process, selectivity of more than 85% degree of 2,6-DMP was achieved. The participation levels of by-products: 2,4-DMP and 2,4,6-TMP were low. In the optimal conditions based on the highest yield of 2,6-DMP achieved in the technological node applying o-cresol circulation, there are 2%mol. of 2,4-DMP and 6%mol. of 2,4,6-TMP in the final mixture, whereas 2,4,6-TMP can be useful as a chain stopper and polymer's molar mass regulator during the polymerization of 2,6-DMP.

  19. Contribution to the knowledge of spouted beds, including in particular an experimental study on the void fraction of the dense phase

    International Nuclear Information System (INIS)

    Eljas, Yves.

    1975-10-01

    The spouted bed is a gas-solid contact technique used to replace fluidisation when the solid particles are too large and too dense. Part one gives a bibliographical study on the aerodynamic aspect of spouted beds. Part two describes an experimental study of the void fraction distribution in a two-dimensional bed [fr

  20. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 1: Process performance and gas product characterization

    DEFF Research Database (Denmark)

    Thomsen, Tobias Pape; Sárossy, Zsuzsa; Gøbel, Benny

    2017-01-01

    Results from five experimental campaigns with Low Temperature Circulating Fluidized Bed (LT-CFB) gasification of straw and/or municipal sewage sludge (MSS) from three different Danish municipal waste water treatment plants in pilot and demonstration scale are analyzed and compared. The gasification...... process is characterized with respect to process stability, process performance and gas product characteristics. All experimental campaigns were conducted at maximum temperatures below 750°C, with air equivalence ratios around 0.12 and with pure silica sand as start-up bed material. A total of 8600kg...... particles in the system. Co-gasification of MSS with sufficient amounts of cereal straw was found to be an effective way to mitigate these issues as well as eliminate thermal MSS drying requirements. Characterization of gas products and process performance showed that even though gas composition varied...

  1. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    Energy Technology Data Exchange (ETDEWEB)

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; John Gaudlip; Matthew Lapinsky; Rhett McLaren; William Serencsits; Neil Raskin; Tom Steitz; Joseph J. Battista

    2003-03-26

    The Pennsylvania State University, utilizing funds furnished by the U.S. Department of Energy's Biomass Power Program, investigated the installation of a state-of-the-art circulating fluidized bed boiler at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring biofuels and coal-based feedstocks. The study was performed using a team that included personnel from Penn State's Energy Institute, Office of Physical Plant, and College of Agricultural Sciences; Foster Wheeler Energy Services, Inc.; Foster Wheeler Energy Corporation; Parsons Energy and Chemicals Group, Inc.; and Cofiring Alternatives. The activities included assessing potential feedstocks at the University Park campus and surrounding region with an emphasis on biomass materials, collecting and analyzing potential feedstocks, assessing agglomeration, deposition, and corrosion tendencies, identifying the optimum location for the boiler system through an internal site selection process, performing a three circulating fluidized bed (CFB) boiler design and a 15-year boiler plant transition plan, determining the costs associated with installing the boiler system, developing a preliminary test program, determining the associated costs for the test program, and exploring potential emissions credits when using the biomass CFB boiler.

  2. Improvement of Combustion Characteristics in Fluidized Bed

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  3. Gas fluidized bed reactor

    International Nuclear Information System (INIS)

    Bernardelli, H. da C.

    1976-03-01

    The equations of motion for both gas and particles in a gas fluidised system are stablished through general assumptions which are generally accepted on physical grounds. The resulting model is used to study the velocity fields of each phase in the case of an isolated bubble rising close to the flat distributor plate. A well posed problem results for the solution of Laplace's equation of the potential flow of the particles when consideration is given to the presence of the distributor as a boundary condition. The corresponding stream functions are also obtained which enable the drawing of the motion patterns using numerical techniques. The following two dimensional cases are analysed: S/b=1; S/b=1,5; S/b=2,5; S/b=5 and the limiting case S/b→αinfinite. The results for the interphase exchange between bubbles and particulate phases are applied to a gas fluidised bed reactor and its effect on the chemical conversion is studied for the simplest cases of piston flow and perfect mixing in the particulate phase [pt

  4. The stability of CaS in circulating fluidized bed boiler residue and the possible release of H2S gas to the atmosphere

    International Nuclear Information System (INIS)

    Mattisson, T.; Lyngfelt, A.

    1995-01-01

    During the combustion of coal, SO 2 is released to the atmosphere. Because of environmental concerns with acid rain, the capture of SO 2 is an important issue. In fluidized bed combustion SO 2 is captured in-situ by limestone or dolomite to form CaSO 4 . This product is stable and can be disposed of or reused as gypsum. In order to capture the sulphur as CaSO 4 oxidizing conditions are necessary. In a fluidized bed boiler (FBB) CaS may form in regions with reducing conditions, and FBB ashes sampled under irregular operating conditions may contain as much as 50 % of the captured sulphur as CaS. The stability of CaS in a landfill environment is thus very important. It is possible that the sulphide decomposes in the presence of moisture or runoff leachate with the subsequent release of H 2 S gas. This re-release of captured sulphur could have a substantial effect on the overall sulphur capture efficiency, with more sulphur released to the atmosphere than previously thought. In this study the stability of CaS in bed ashes from a 12 MW circulating FBB combusting coal has been investigated, with focus on the release of H 2 S gas. (orig.)

  5. Pyrolysis of high-ash sewage sludge in a circulating fluidized bed reactor for production of liquids rich in heterocyclic nitrogenated compounds.

    Science.gov (United States)

    Zuo, Wu; Jin, Baosheng; Huang, Yaji; Sun, Yu; Li, Rui; Jia, Jiqiang

    2013-01-01

    A circulating fluidized bed reactor was used for pyrolyzing sewage sludge with a high ash content to produce liquids rich in heterocyclic nitrogenated compounds. GC/MS and FTIR analyses showed that heterocyclic nitrogenated compounds and hydrocarbons made up 38.5-61.21% and 2.24-17.48% of the pyrolysis liquids, respectively. A fluidized gas velocity of 1.13 m/s, a sludge feed rate of 10.78 kg/h and a particle size of 1-2mm promoted heterocyclic nitrogenated compound production. Utilizing heterocyclic nitrogenated compounds as chemical feedstock could be a way for offsetting the cost of sewage sludge treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. On natural circulation in High Temperature Gas-Cooled Reactors and pebble bed reactors for different flow regimes and various coolant gases

    International Nuclear Information System (INIS)

    Melesed'Hospital, G.

    1983-01-01

    The use of CO 2 or N 2 (heavy gas) instead of helium during natural circulation leads to improved performance in both High Temperature Gas-Cooled Reactors (HTGR) and in Pebble Bed Reactors (PBR). For instance, the coolant temperature rise corresponding to a coolant pressure level and a rate of afterheat removal could be only 18% with CO 2 as compared to He, for laminar flow in HTGR; this value would be 40% in PBR. There is less difference between HTGR and PBR for turbulent flows; CO 2 is found to be always better than N 2 . These types of results derived from relationships between coolant properties, coolant flow, temperature rise, pressure, afterheat levels and core geometry, are obtained for HTGR and PBR for various flow regimes, both within the core and in the primary loop

  7. Survey of radionuclide emissions from coal-fired power plants and examination of impacts from a proposed circulating fluidized bed boiler power plant

    International Nuclear Information System (INIS)

    Steiner, C.P.; Militana, L.M.; Harvey, K.A.; Kinsey, G.D.

    1995-01-01

    This paper presents the results of a literature survey that examined radionuclide emissions from coal-fired power plants. Literature references from both the US and foreign countries are presented. Emphasis is placed on references from the US because the radionuclide emissions from coal-fired power plants are related to radionuclide concentrations in the coal, which vary widely throughout the world. The radionuclides were identified and quantified for various existing power plants reported in the literature. Applicable radionuclide emissions criteria discovered in the literature search were then applied to a proposed circulating fluidized bed boiler power plant. Based upon the derived radionuclide emission rates applied to the proposed power plant, an air quality modeling analysis was performed. The estimated ambient concentrations were compared to the most relevant existing regulatory ambient levels for radionuclides

  8. Co-firing of oil sludge with coal-water slurry in an industrial internal circulating fluidized bed boiler.

    Science.gov (United States)

    Liu, Jianguo; Jiang, Xiumin; Zhou, Lingsheng; Wang, Hui; Han, Xiangxin

    2009-08-15

    Incineration has been proven to be an alternative for disposal of sludge with its unique characteristics to minimize the volume and recover energy. In this paper, a new fluidized bed (FB) incineration system for treating oil sludge is presented. Co-firing of oil sludge with coal-water slurry (CWS) was investigated in the new incineration system to study combustion characteristics, gaseous pollutant emissions and ash management. The study results show the co-firing of oil sludge with CWS in FB has good operating characteristic. CWS as an auxiliary fuel can flexibly control the dense bed temperatures by adjusting its feeding rate. All emissions met the local environmental requirements. The CO emission was less than 1 ppm or essentially zero; the emissions of SO(2) and NO(x) were 120-220 and 120-160 mg/Nm(3), respectively. The heavy metal analyses of the bottom ash and the fly ash by ICP/AES show that the combustion ashes could be recycled as soil for farming.

  9. Boiler plants completed in record time

    International Nuclear Information System (INIS)

    Anon.

    2001-01-01

    Bubbling fluidised bed (BFB) combustion has steadily increased its share of the boiler market in recent years, particularly in the Nordic region, where it is particularly well-suited to handling the high moisture content biofuels produced and used by the forest products industry. Foster Wheeler is the world's leading supplier of fluidised bed combustion technology. Over 200 of the more than 300 fluidised bed boilers supplied by the company are circulating fluidised bed (CFB) designs, a market in which Foster Wheeler has more than a 40% share. Foster Wheeler Energia Oy supplied the Myllykoski project at Anjalankoski with a fluidised bed boiler, auxiliary steam boilers, and flue gas scrubber systems

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

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

  11. FEASIBILITY ANALYSIS FOR INSTALLING A CIRCULATING FLUIDIZED BED BOILER FOR COFIRING MULTIPLE BIOFUELS AND OTHER WASTES WITH COAL AT PENN STATE UNIVERSITY

    International Nuclear Information System (INIS)

    Bruce G. Miller; Sharon Falcone Miller; Robert Cooper; Douglas Donovan; John Gaudlip; Matthew Lapinsky; William Serencsits; Neil Raskin; Dale Lamke; Joseph J. Battista

    2001-01-01

    The Pennsylvania State University, under contract to the U.S. Department of Energy (DOE), National Energy Technology Laboratory (NETL) is performing a feasibility analysis on installing a state-of-the-art circulating fluidized bed (CFB) boiler and ceramic filter emission control device at Penn State's University Park campus for cofiring multiple biofuels and other wastes with coal, and developing a test program to evaluate cofiring multiple biofuels and coal-based feedstocks. Penn State currently operates an aging stoker-fired steam plant at its University Park campus and has spent considerable resources over the last ten to fifteen years investigating boiler replacements and performing life extension studies. This effort, in combination with a variety of agricultural and other wastes generated at the agricultural-based university and the surrounding rural community, has led Penn State to assemble a team of fluidized bed and cofiring experts to assess the feasibility of installing a CFB boiler for cofiring biomass and other wastes along with coal-based fuels. The objective of the project is being accomplished using a team that includes personnel from Penn State's Energy Institute and the Office of Physical Plant, Foster Wheeler Energy Services, Inc., and Cofiring Alternatives

  12. CFD simulation of CO_2 sorption on K_2CO_3 solid sorbent in novel high flux circulating-turbulent fluidized bed riser: Parametric statistical experimental design study

    International Nuclear Information System (INIS)

    Thummakul, Theeranan; Gidaspow, Dimitri; Piumsomboon, Pornpote; Chalermsinsuwan, Benjapon

    2017-01-01

    Highlights: • Circulating-turbulent fluidization was proved to be advantage on CO_2 sorption. • The novel regime was proven to capture CO_2 higher than the conventional regimes. • Uniform solid particle distribution was observed in the novel fluidization regime. • The system continuity had more effect in the system than the process system mixing. • Parametric experimental design analysis was studied to evaluate significant factor. - Abstract: In this study a high flux circulating-turbulent fluidized bed (CTFB) riser was confirmed to be advantageous for carbon dioxide (CO_2) sorption on a potassium carbonate solid sorbent. The effect of various parameters on the CO_2 removal level was evaluated using a statistical experimental design. The most appropriate fluidization regime was found to occur between the turbulent and fast fluidization regimes, which was shown to capture CO_2 more efficiently than conventional fluidization regimes. The highest CO_2 sorption level was 93.4% under optimized CTFB operating conditions. The important parameters for CO_2 capture were the inlet gas velocity and the interactions between the CO_2 concentration and the inlet gas velocity and water vapor concentration. The CTFB regime had a high and uniform solid particle distribution in both the axial and radial system directions and could transport the solid sorbent to the regeneration reactor. In addition, the process system continuity had a stronger effect on the CO_2 removal level in the system than the process system mixing.

  13. Fiscal 1995 survey report on the environmentally friendly type coal utilization system introduction support project. Verification project on the circulating fluidized bed boiler; Kankyo chowagata sekitan riyo system donyu shien jigyo. Junkan ryudosho boiler ni kakawaru jissho jigyo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    In relation to the circulating fluidized bed boiler which reduces the amount of sulfur oxides emitted in coal utilization, a verification project was carried out on installation of the equipment and spread activity in China and the Philippines contributing to the control of environmental pollutant associated with coal utilization and the effective use of energy. At the Fanshan area, installed was a 10t/h internal circulating fluidized bed boiler. At the performance test, coal includes around 7% of impurities such as stone, and the impurities should be excluded continuously at the time of actual run. Therefore, the boiler efficiency had to be changed from 89.5% to 85.8%. Further, power generation facilities have not yet been finished, and the overall operation of boiler turbine has not been executed. At the Zibo area, a 30t/h external circulating fluidized bed boiler was installed. The boiler efficiency reached 86.1%, over the targeted value. At the Batangas area in the Philippines, a 10t/h internal circulating fluidized bed boiler was installed. The boiler efficiency reached 85.8%, over the designed value. About the coal produced in the Philippines, slagging was feared, but the combustion state was favorable. 82 figs., 21 tabs.

  14. Measurement of Gas Velocities in the Presence of Solids in the Riser of a Cold Flow Circulating Fluidized Bed

    International Nuclear Information System (INIS)

    Spenik, J.; Ludlow, J.C.; Compston, R.; Breault, R.W.

    2007-01-01

    The local gas velocity and the intensity of the gas turbulence in a gas/solid flow are a required measurement in validating the gas and solids flow structure predicted by computational fluid dynamic (CFD) models in fluid bed and transport reactors. The high concentration and velocities of solids, however, make the use of traditional gas velocity measurement devices such as pitot tubes, hot wire anemometers and other such devices difficult. A method of determining these velocities has been devised at the National Energy Technology Laboratory employing tracer gas. The technique developed measures the time average local axial velocity gas component of a gas/solid flow using an injected tracer gas which induces changes in the heat transfer characteristics of the gas mixture. A small amount of helium is injected upstream a known distance from a self-heated thermistor. The thermistor, protected from the solids by means of a filter, is exposed to gases that are continuously extracted from the flow. Changes in the convective heat transfer characteristics of the gas are indicated by voltage variations across a Wheatstone bridge. When pulsed injections of helium are introduced to the riser flow the change in convective heat transfer coefficient of the gas can be rapidly and accurately determined with this instrument. By knowing the separation distance between the helium injection point and the thermistor extraction location as well as the time delay between injection and detection, the gas velocity can easily be calculated. Variations in the measured gas velocities also allow the turbulence intensity of the gas to be estimated

  15. Biodegradation of 2,4,6-trichlorophenol in a packed-bed biofilm reactor equipped with an internal net draft tube riser for aeration and liquid circulation

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-De Jesus, A.; Romano-Baez, F.J.; Leyva-Amezcua, L.; Juarez-Ramirez, C.; Ruiz-Ordaz, N. [Departamento de Ingenieria Bioquimica, Escuela Nacional de Ciencias Biologicas, IPN. Prol. Carpio y Plan de Ayala, Colonia Santo Tomas, s/n. CP 11340, Mexico, D.F. (Mexico); Galindez-Mayer, J. [Departamento de Ingenieria Bioquimica, Escuela Nacional de Ciencias Biologicas, IPN. Prol. Carpio y Plan de Ayala, Colonia Santo Tomas, s/n. CP 11340, Mexico, D.F. (Mexico)], E-mail: cmayer@encb.ipn.mx

    2009-01-30

    For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for liquid circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high A{sub D}/A{sub R} ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values {epsilon}{sub G}, and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies ({approx}95%), and by the stoichiometric release of chloride ions from the halogenated compound ({approx}80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions)

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  17. Development and Implementation of 3-D, High Speed Capacitance Tomography for Imaging Large-Scale, Cold-Flow Circulating Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Marashdeh, Qussai [Tech4imaging LLC, Columbus, OH (United States)

    2013-02-01

    A detailed understanding of multiphase flow behavior inside a Circulating Fluidized Bed (CFB) requires a 3-D technique capable of visualizing the flow field in real-time. Electrical Capacitance Volume Tomography (ECVT) is a newly developed technique that can provide such measurements. The attractiveness of the technique is in its low profile sensors, fast imaging speed and scalability to different section sizes, low operating cost, and safety. Moreover, the flexibility of ECVT sensors enable them to be designed around virtually any geometry, rendering them suitable to be used for measurement of solid flows in exit regions of the CFB. Tech4Imaging LLC has worked under contract with the U.S. Department of Energy's National Energy Technology Laboratory (DOE NETL) to develop an ECVT system for cold flow visualization and install it on a 12 inch ID circulating fluidized bed. The objective of this project was to help advance multi-phase flow science through implementation of an ECVT system on a cold flow model at DOE NETL. This project has responded to multi-phase community and industry needs of developing a tool that can be used to develop flow models, validate computational fluid dynamics simulations, provide detailed real-time feedback of process variables, and provide a comprehensive understating of multi-phase flow behavior. In this project, a complete ECVT system was successfully developed after considering different potential electronics and sensor designs. The system was tested at various flow conditions and with different materials, yielding real-time images of flow interaction in a gas-solid flow system. The system was installed on a 12 inch ID CFB of the US Department of Energy, Morgantown Labs. Technical and economic assessment of Scale-up and Commercialization of ECVT was also conducted. Experiments conducted with larger sensors in conditions similar to industrial settings are very promising. ECVT has also the potential to be developed for imaging multi

  18. Advanced treatment of biologically pretreated coal chemical industry wastewater using the catalytic ozonation process combined with a gas-liquid-solid internal circulating fluidized bed reactor.

    Science.gov (United States)

    Li, Zhipeng; Liu, Feng; You, Hong; Ding, Yi; Yao, Jie; Jin, Chao

    2018-04-01

    This paper investigated the performance of the combined system of catalytic ozonation and the gas-liquid-solid internal circulating fluidized bed reactor for the advanced treatment of biologically pretreated coal chemical industry wastewater (CCIW). The results indicated that with ozonation alone for 60min, the removal efficiency of chemical oxygen demand (COD) could reach 34%. The introduction of activated carbon, pumice, γ-Al 2 O 3 carriers improved the removal performance of COD, and the removal efficiency was increased by 8.6%, 4.2%, 2%, respectively. Supported with Mn, the catalytic performance of activated carbon and γ-Al 2 O 3 were improved significantly with COD removal efficiencies of 46.5% and 41.3%, respectively; however, the promotion effect of pumice supported with Mn was insignificant. Activated carbon supported with Mn had the best catalytic performance. The catalytic ozonation combined system of MnO X /activated carbon could keep ozone concentration at a lower level in the liquid phase, and promote the transfer of ozone from the gas phase to the liquid phase to improve ozonation efficiency.

  19. Experimental study on dew point corrosion characteristics of the heating surface in a 65 t/h biomass-fired circulating fluidized bed boiler

    International Nuclear Information System (INIS)

    Wang, Yungang; Ma, Haidong; Liang, Zhiyuan; Chen, Heng; Zhao, Qinxin; Jin, Xin

    2016-01-01

    Highlights: • Dew point corrosion and ash deposit tests in a biomass-fired boiler were performed. • The XRD, XRF and SEM methods were used to analyze corrosion samples. • The deposits were made up of ash deposit layer, coupling layer and corrosion layer. • The metal matrix simultaneously confronted chlorine corrosion and oxygen corrosion. - Abstract: The dew point corrosion characteristics of the heating surface in a 65 t/h biomass-fired circulating fluidized bed (CFB) boiler were experimentally studied. The cross-sectional morphology and composition of the ash deposition were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray fluorescence spectrum (XRF), respectively. The results showed that the test tube surface was covered by ash deposit layer, coupling layer and corrosion layer. The ash deposit layer and the coupling layer were prone to spall off together. The coupling layer consists of partial ash and corrosion products. The corrosion layer was mainly composed of chlorides (FeCl_3, FeCl_2, and FeOCl) and oxides (FeOOH, Fe_2O_3). With the increase of the tube wall temperature, the corrosion depth decreased dramatically and the dew point corrosion was alleviated efficiently. The metal matrix simultaneously suffered from chlorine corrosion and oxygen corrosion. As the tube wall temperature was above water dew point, the main corrosion mode was oxygen corrosion. As the tube wall temperature was below water dew point, the main corrosion mode was chlorine corrosion.

  20. Gasification of algal biomass (Cladophora glomerata L.) with CO2/H2O/O2 in a circulating fluidized bed.

    Science.gov (United States)

    Ebadi, Abdol Ghaffar; Hisoriev, Hikmat

    2017-11-28

    Gasification is one of the most important thermochemical routes to produce both synthesis gas (syngas) and chars. The quality of produced syngas wieldy depends on the operating conditions (temperature, residence time, heating rate, and gasifying agent), hydrodynamic properties of gasifier (particle size, minimum fluidization velocity, and gasifier size), and type of feedstock (coal, biomass, oil, and municipal solid wastes). In the present study, simulation of syngas production via circulating fluidized bed (CFB) gasification of algal biomass (Cladophora glomerata L.) at different gasifying agents and particle sizes was carried out, using Aspen Plus simulator. The model which has been validated by using experimental data of the technical literature was used to evaluate the influence of operating conditions on gas composition and performance parameters. The results show that biomass gasification using pure oxygen as the gasification agent has great potential to improve the caloric value of produced gas and performance indicators. It was also found that the produced gas caloric value, syngas yield, and performance parameters (CCE and CGE) increase with reaction temperature but are inversely proportional to the biomass particle size.

  1. Simulations of a Circulating Fluidized Bed Chemical Looping Combustion System Utilizing Gaseous Fuel Simulation de la combustion en boucle chimique d’une charge gazeuse dans un lit fluidisé circulant

    Directory of Open Access Journals (Sweden)

    Mahalatkar K.

    2011-05-01

    Full Text Available Numerical studies using Computational Fluid Dynamics (CFD have been carried out for a complete circulating fluidized bed chemical looping combustor described in the literature (Abad et al., 2006 Fuel 85, 1174-1185. There have been extensive experimental studies in Chemical Looping Combustion (CLC, however CFD simulations of this concept are quite limited. The CLC experiments that were simulated used methane as fuel. A 2-D continuum model was used to describe both the gas and solid phases. Detailed sub-models to account for fluid-particle and particleparticle interaction forces were included. Global models of fuel and carrier chemistry were utilized. The results obtained from CFD were compared with experimental outlet species concentrations, solid circulation rates, solid mass distribution in the reactors, and leakage and dilution rates. The transient CFD simulations provided a reasonable match with the reported experimental data. Des études numériques de simulation des écoulements (CFD ont été réalisées sur un lit fluidisé circulant opérant en combustion par boucle chimique (CLC décrit dans la littérature (Abad et al., 2006 Fuel 85, 1174-1185. Si de nombreuses études expérimentales ont été conduites pour étudier le procédé CLC, les études concernant la simulation des écoulements par CFD de ce concept sont très limitées. Le système de combustion en boucle chimique simulé dans cette étude concerne la combustion d’une charge gazeuse (méthane. Un modèle 2-D à deux phases continues a été utilisé pour décrire les phases gaz et solide avec des sous-modèles détaillés pour décrire les forces d’interactions entre fluideparticule et particule-particule. Des modèles cinétiques globaux ont été intégrés pour décrire les réactions de combustion et de transformation du matériau transporteur d’oxygène. Les résultats obtenus par CFD ont été comparés aux concentrations expérimentales mesurées des diff

  2. Technical and economical optimization of wood gasification in a circulating fluidized bed. Final report; Technische und wirtschaftliche Optimierung der Vergasung von Holz in der zirkulierenden Wirbelschicht. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Ising, M.; Unger, C.; Heunemann, F.; Dinkelbach, L.

    2002-12-01

    The project's objective was the optimization of a novel process for high efficient combined heat and power production from solid biomass. The processed air blown wood gasification in a pilot scale circulating fluidized bed was added by a catalytic tar reformer which would yield a tar-free gas quality suitable for IC-engine operation. Major efforts were taken for technical improvement of the tar reformer, especially concerning temperature control and cleaning devices which is important for keeping constantly a high activity. Pure natural timber did not yield chemical deactivation at the catalyst whereas the gasification of waste wood yielded decreasing activity which could be partly reversed by special measures taken. Further optimization of the process considered a better automation and improvement of the engine's flue gas emissions. Also a detailed economic consideration and evaluation of the entire process has been carried out. As a result the novel process should have economic advantages compared with conventional technology. (orig.) [German] Gegenstand des Vorhabens war die Weiterentwicklung eines Verfahrens zur effizienteren Strom- und Waermegewinnung aus festen Biobrennstoffen. Durch luftgeblasene Vergasung von Holz im Pilotmassstab in einer zirkulierenden Wirbelschicht und anschliessender katalytischer Teerspaltung konnte ein niederkalorisches Brenngas erzeugt werden, welches zum Betrieb eines Motoren-Blockheizkraftwerks geeignet war. Im Rahmen der Verfahrensoptimierung wurde der katalytische Teer-Reformer, insbesondere in Bezug auf Temperaturfuehrung und die zum Aktivitaetserhalt wichtige Abreinigungsvorrichtung, verbessert. Bei der Vergasung von Naturholz wurde keine chemische Desaktivierung festgestellt. Beim Altholzeinsatz wurde ein ueberwiegend reversibler Aktivitaetsverlust verzeichnet und begruendet. Geeignete Gegenmassnahmen wurden untersucht und beschrieben. Weitere Optimierungen betrafen die Anlagensteuerungstechnik im Hinblick auf die

  3. Adaptive monitoring of emissions in energy boilers using self-organizing maps: An application to a biomass-fired CFB (circulating fluidized bed)

    International Nuclear Information System (INIS)

    Liukkonen, M.; Hiltunen, T.

    2014-01-01

    Improvement of energy efficiency, reduction of operating costs, and reduction of harmful emissions released into the atmosphere are issues of major concern in modern energy plants. While air emissions have to be restricted due to tightening environmental legislation, at the same time it is ever more important to be able to respond quickly to any changes in the load demand or fuel quality. As unpredictability increases with changing fuel quality and more complex operational strategies, undesired phenomena such as increased emission release rates may become more likely. Therefore, it is crucial that emission monitoring systems are able to adapt to varying conditions, and advanced methodologies are needed for monitoring and decision-support. In this paper a novel approach for advanced monitoring of emissions in CFB (circulating fluidized bed) boilers is described. In this approach a model based on SOM (self-organizing maps) is updated regularly to respond to the prevailing condition of the boiler. After creating each model a new set of measurements is input to the system, and the current state of the process is determined using vector distance calculation. Finally, the system evaluates the current condition and may alert if a preset limit defined for each emission component is exceeded. - Highlights: • An adaptive monitoring approach based on self-organizing maps is presented. • The system can monitor the current state of a combustion process and its emissions. • The system is designed to alert when the preset limits defined for emissions are exceeded. • Due to regular updating routine the system is able to adapt to changing conditions. • The application is demonstrated using data from a biomass-fired energy boiler

  4. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 2: Evaluation of ash materials as phosphorus fertilizer.

    Science.gov (United States)

    Thomsen, Tobias Pape; Hauggaard-Nielsen, Henrik; Gøbel, Benny; Stoholm, Peder; Ahrenfeldt, Jesper; Henriksen, Ulrik B; Müller-Stöver, Dorette Sophie

    2017-08-01

    The study is part 2 of 2 in an investigation of gasification and co-gasification of municipal sewage sludge in low temperature gasifiers. In this work, solid residuals from thermal gasification and co-gasification of municipal sewage sludge were investigated for their potential use as fertilizer. Ashes from five different low temperature circulating fluidized bed (LT-CFB) gasification campaigns including two mono-sludge campaigns, two sludge/straw mixed fuels campaigns and a straw reference campaign were compared. Experiments were conducted on two different LT-CFBs with thermal capacities of 100kW and 6MW, respectively. The assessment included: (i) Elemental composition and recovery of key elements and heavy metals; (ii) content of total carbon (C) and total nitrogen (N); (iii) pH; (iv) water extractability of phosphorus after incubation in soil; and (v) plant phosphorus response measured in a pot experiment with the most promising ash material. Co-gasification of straw and sludge in LT-CFB gasifiers produced ashes with a high content of recalcitrant C, phosphorus (P) and potassium (K), a low content of heavy metals (especially cadmium) and an improved plant P availability compared to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottom ashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded that LT-CFB gasification and co-gasification is a highly effective way to purify and sanitize sewage sludge for subsequent use in agricultural systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Gasification of secondary fuels in a circulating fluidized bed for energetic use in cement production; Vergasung von Sekundaerbrennstoffen in der zirkulierenden Wirbelschicht zur energetischen Nutzung fuer die Zementherstellung

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, J; Gafron, B [Lurgi Umwelt GmbH, Frankfurt am Main (Germany); Scur, P; Wirthwein, R [Ruedersdorfer Zement GmbH (Germany)

    1998-09-01

    Ruedersforf cement factory was commissioned a century ago as one of the first in Germany. After the plant was taken over by Readymix AG, a comprehensive sanitation concept was carried through. The plant has a production capacity of 8000 t/d of cement clinkers which are produced in a new kiln with a capacity of 6000 t/d and two modernized kilns each with a capacity of 1000 t/d. Reduction of energy consumption was the main goal of modernisation, with fuel gas generation in a circulating fluidized bed as a key element. The unit provides 40 % of the energy consumed by the clinker production process and is also used for selective ash production up to 25 t/h. The ash is used as a raw material for cement production. (orig./SR) [Deutsch] Bereits vor 100 Jahren wurde eine der ersten Zementfabriken in Deutschland am Standort Ruedersdorf in Betrieb genommen. Zum Erhalt der Wettbewerbsfaehigkeit wurde nach der Uebernahme des Werkes Ruedersdorf durch die Readymix AG ein umfangreiches Sanierungskonzept in die Wege geleitet. Bei einer Produktionskapazitaet von ca. 8 000 t Klinker pro Tag werden eine neue Ofenanlage mit einer Kapazitaet von 6 000 t/Tag sowie 2 sanierte kleine Anlagen zu je 1000 t/Tag betrieben. In der neuen Ofenanlage werden alle Moeglichkeiten genutzt, den Energiebedarf fuer die Klinkerproduktion zu senken. Eine wesentliche neue innovative Komponente ist dabei eine Brenngaserzeugung in einer Zirkulierenden Wirbelschicht, ueber die im folgenden berichtet werden soll. Die Anlage kann bis zu 40% des Energiebedarfes des Zementprozesses liefern. Weiterhin wird mit der ZWS eine gezielte Ascheproduktion, bis zu 25 t/h, betrieben. Diese Aschen sind Teil der Rohstoffrezeptur an der Rohmuehle. (orig./SR)

  6. FY 1999 report on the potential survey of the environmental friendly type coal utilization system. Survey on the spread/promotion of circulating fluidized bed boilers in China; 1999 nendo chosa hokoksho. Kankyo chowagata sekitan riyo system kanosei chosa. Chugoku ni okeru junkan yukaboira no fukyu sokushin ni kakawaru chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    For the purpose of contributing to the spread/promotion of Japanese-make circulating fluidized bed boilers with desulfurization function, survey was conducted of the state of utilization of circulating fluidized bed boilers, the needs, etc. in China. In the survey, field survey was made at two boiler manufacturers and four companies using boilers in Beijing city, Fujian province, Hubei province, etc. to grasp the state of utilization and study conditions for the spread/promotion of circulating fluidized bed boilers. The Chinese government is making efforts for the spread of circulating fluidized bed boilers. The number of the domestically existing circulating fluidized bed boilers is estimated at approximately 800, but almost none of them conducts furnace desulfurization. Further, the operating rate of boiler is not always high. The reasons are as follows: desulfurization costs high without connecting to the production; environmental regulation is still mild in China; reliability and maintenance technique are still at low levels. It is urgently desirable to spread highly reliable circulating fluidized bed boilers with desulfurization function, and accordingly, it is necessary to reduce the cost of Japanese-make boilers. (NEDO)

  7. Emission characteristics for gaseous- and size-segregated particulate PAHs in coal combustion flue gas from circulating fluidized bed (CFB) boiler.

    Science.gov (United States)

    Wang, Ruwei; Liu, Guijian; Sun, Ruoyu; Yousaf, Balal; Wang, Jizhong; Liu, Rongqiong; Zhang, Hong

    2018-07-01

    The partitioning behavior of polycyclic aromatic hydrocarbons (PAHs) between gaseous and particulate phases from coal-fired power plants (CFPPs) is critically important to predict PAH removal by dust control devices. In this study, 16 US-EPA priority PAHs in gaseous and size-segregated particulate phases at the inlet and outlet of the fabric filter unit (FFs) of a circulating fluidized bed (CFB) boiler were analyzed. The partitioning mechanisms of PAHs between gaseous and particulate phases and in particles of different size classes were investigated. We found that the removal efficiencies of PAHs are 45.59% and 70.67-89.06% for gaseous and particulate phases, respectively. The gaseous phase mainly contains low molecular weight (LMW) PAHs (2- and 3-ring PAHs), which is quite different from the particulate phase that mainly contains medium and high molecular weight (MMW and HMW) PAHs (4- to 6-ring PAHs). The fractions of LMW PAHs show a declining trend with the decrease of particle size. The gas-particle partitioning of PAHs is primarily controlled by organic carbon absorption, in addition, it has a clear dependence on the particle sizes. Plot of log (TPAH/PM) against logD p shows that all slope values were below -1, suggesting that PAHs were mainly adsorbed to particulates. The adsorption effect of PAHs in size-segregated PMs for HMW PAHs is more evident than LMW PAHs. The particle size distributions (PSDs) of individual PAHs show that most of PAHs exhibit bi-model structures, with one mode peaking in the accumulation size range (2.1-1.1 μm) and another mode peaking in coarse size range (5.8-4.7 μm). The intensities of these two peaks vary in function of ring number of PAHs, which is likely attributed to Kelvin effect that the less volatile HMW PAH species preferentially condense onto the finer particulates. The emission factor of PAHs was calculated as 3.53 mg/kg of coal burned, with overall mean EF PAH of 0.55 and 2.98 mg/kg for gaseous and particulate

  8. The enrichment of natural radionuclides in oil shale-fired power plants in Estonia – The impact of new circulating fluidized bed technology

    International Nuclear Information System (INIS)

    Vaasma, Taavi; Kiisk, Madis; Meriste, Tõnis; Tkaczyk, Alan Henry

    2014-01-01

    Burning oil shale to produce electricity has a dominant position in Estonia's energy sector. Around 90% of the overall electric energy production originates from the Narva Power Plants. The technology in use has been significantly renovated – two older types of pulverized fuel burning (PF) energy production units were replaced with new circulating fluidized bed (CFB) technology. Additional filter systems have been added to PF boilers to reduce emissions. Oil shale contains various amounts of natural radionuclides. These radionuclides concentrate and become enriched in different boiler ash fractions. More volatile isotopes will be partially emitted to the atmosphere via flue gases and fly ash. To our knowledge, there has been no previous study for CFB boiler systems on natural radionuclide enrichment and their atmospheric emissions. Ash samples were collected from Eesti Power Plant's CFB boiler. These samples were processed and analyzed with gamma spectrometry. Activity concentrations (Bq/kg) and enrichment factors were calculated for the 238 U ( 238 U, 226 Ra, 210 Pb) and 232 Th ( 232 Th, 228 Ra) family radionuclides and for 40 K in different CFB boiler ash fractions. Results from the CFB boiler ash sample analysis showed an increase in the activity concentrations and enrichment factors (up to 4.5) from the furnace toward the electrostatic precipitator block. The volatile radionuclide ( 210 Pb and 40 K) activity concentrations in CFB boilers were evenly distributed in finer ash fractions. Activity balance calculations showed discrepancies between input (via oil shale) and output (via ash fractions) activities for some radionuclides ( 238 U, 226 Ra, 210 Pb). This refers to a situation where the missing part of the activity (around 20% for these radionuclides) is emitted to the atmosphere. Also different behavior patterns were detected for the two Ra isotopes, 226 Ra and 228 Ra. A part of 226 Ra input activity, unlike 228 Ra, was undetectable in the solid

  9. Particulate Emissions from Fluidised Bed Combustion of Ligite with Mineral Sorbents

    Czech Academy of Sciences Publication Activity Database

    Smolík, Jiří; Schwarz, Jaroslav; Ondráčková, Lucie; Veselý, Václav; Sýkorová, Ivana; Kučera, Jan; Havránek, Vladimír

    2000-01-01

    Roč. 31, Suppl. 1 (2000), s. S670-S671 ISSN 0021-8502. [European Aerosol Conference 2000. Dublin, 03.09.2000-08.09.2000] R&D Projects: GA ČR GA104/00/1297; GA AV ČR IAA2046904 Institutional research plan: CEZ:AV0Z4072921; CEZ:AV0Z3046908 Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.071, year: 2000

  10. Co-gasification of biomass and coal in a pressurised fluidised bed gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Andries, L.; Hein, K.R.G. [Lab. for Thermal Power Engineering, Dept. of Mechanical Engineering and Marine Technology, Delft Univ. of Technology (Netherlands)

    1996-12-31

    The Laboratory for Thermal Power Engineering of the Delft University of Technology is participating in an EU funded, international, R + D project which is designed to aid European industry in addressing issues regarding co-utilisation of biomass and/or waste in advanced coal conversion processes. The project comprises three main programmes, each of which includes a number of smaller subprogrammes. The three main programmes are: Coal-biomass systems component development and design; Coal-biomass environmental studies; Techno-economic assessment studies. (orig)

  11. Utilization of post-reclamation dusts by combustion and oxidising in a pulsating, fluidised bed

    Directory of Open Access Journals (Sweden)

    J. Dańko

    2008-03-01

    Full Text Available Invcaigations of thc urilization process of durn. originated from thc mcchanical scclamatbn of uscd moulding sands with Furfury1 alcohol.werc pcrformcd. Colnbustion and oxidat ion processes of pulvcriscd and scparatetl in cycloncs binding agcnts and othcr organiccomponents wcrc carricd out in thc thcrmal mlairncr wherc a grain hcd ~mdcnvent pulsating fluidisat ion cithcs by thc atmnsphcric air orhy oxypcn cnriched air. Factors dclcrmining an effective pcrlormancc of dusls utilization by oxidising in rhc oxygcn cncichcd air wcreindicated and thc plan for thc Furthcr rcscwch was outlined.

  12. Mathematical Determination of Thermal Load for Fluidised Bed Furnaces Using Sawdust

    Directory of Open Access Journals (Sweden)

    Antonescu Nicolae

    2014-06-01

    Full Text Available For technical applications, a physical model capable of predicting the particle evolution in the burning process along its trajectory through the furnace is very useful. There are two major demands: all the thermo-dynamic processes that describe the particle burning process must be accounted and the model must be written in such equation terms to allow the intervention for parameter settings and particle definition. The computations were performed for the following parameters: furnace average temperature between 700 and 1200 °C, size of the sawdust particle from 4 to 6 mm and fix carbon ignition between 500 and 900 °C. The values obtained for the characteristic parameters of the burning process ranged from 30 to 60 [kg/(h·m3] for the gravimetrical burning speed WGh and from 150 to 280 [kW/m3] for the volumetric thermal load of the furnace QV. The main conclusion was that the calculus results are in good agreement with the experimental data from the pilot installations and the real-case measurements in the sawdust working boiler furnaces or pre-burning chambers. Another very important conclusion is that the process speed variation, when the furnace temperature changes, confirms the thermo-kinetic predictions, namely that the burning process speed decreases when the furnace temperature increases.

  13. Co-gasification of biomass and coal in a pressurised fluidised bed gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Andries, L; Hein, K R.G. [Lab. for Thermal Power Engineering, Dept. of Mechanical Engineering and Marine Technology, Delft Univ. of Technology (Netherlands)

    1997-12-31

    The Laboratory for Thermal Power Engineering of the Delft University of Technology is participating in an EU funded, international, R + D project which is designed to aid European industry in addressing issues regarding co-utilisation of biomass and/or waste in advanced coal conversion processes. The project comprises three main programmes, each of which includes a number of smaller subprogrammes. The three main programmes are: Coal-biomass systems component development and design; Coal-biomass environmental studies; Techno-economic assessment studies. (orig)

  14. Fluidised bed gasification of South African coals – experimental results and process integration

    CSIR Research Space (South Africa)

    Engelbrecht, A

    2011-06-01

    Full Text Available % to 51.6%. The new design however requires a significantly larger heat exchange area to exchange the extra energy that was not exchanged in the preliminary design. It is therefore recommended that a cost analysis should be done to determine whether...

  15. Co-firing coal and biomass in a fluidised bed boiler

    CSIR Research Space (South Africa)

    North, BC

    2005-11-01

    Full Text Available ) Nozzle performance trials iv) Large scale combustion trials (including further pumping trials). These phases are covered in greater detail below. Theoretical Studies The first step was to draw up a composite fuel table, where the relative feed.... An example is given in Table 2C. Deviations from theoretical behaviour were investigated, reasons postulated and solutions proposed. Nozzle Performance Trials Trials were carried out at the client’s premises and at the CSIR in order to determine...

  16. Nitrogen compounds in pressurised fluidised bed gasification of biomass and fossil fuels

    NARCIS (Netherlands)

    De Jong, W.

    2005-01-01

    Fossil fuels still dominate the energy supply in modern societies. The resources, however, are depleting. Therefore, other energy sources are to be exploited further within this century. Biomass is one of the practically CO2 neutral, renewable contributors to the future energy production. Nowadays

  17. Reactions homogenes en phase gazeuse dans les lits fluidises

    Science.gov (United States)

    Laviolette, Jean-Philippe

    This thesis presents a study on homogeneous gas-phase reactions in fluidized beds. The main objective is to develop new tools to model and characterize homogeneous gas-phase reactions in this type of reactor. In the first part of this work, the non-premixed combustion of C 1 to C4 n-alkanes with air was investigated inside a bubbling fluidized bed of inert sand particles at intermediate temperatures: 923 K ≤ TB ≤ 1123 K. For ethane, propane and n-butane, combustion occurred mainly in the freeboard region at bed temperatures below T1 = 923 K. On the other hand, complete conversion occurred within 0.2 m of the injector at: T2 = 1073 K. For methane, the measured values of T1 and T2 were significantly higher at 1023 K and above 1123 K, respectively. The fluidized bed combustion was accurately modeled with first-order global kinetics and two one-phase PFR models in series: one PFR to model the region close to the injector and another to represent the main fluidized bed body. The measured global reaction rates for C2 to C4 n-alkanes were characterized by a uniform Arrhenius expression, while the global reaction rate for methane was significantly slower. Reactions in the injector region either led to significant conversion in that zone or an autoignition delay inside the main fluidized bed body. The conversion in the injector region increased with rising fluidized bed temperature and decreased with increasing jet velocity. To account for the promoting and inhibiting effects, an analogy was made with the concept of induction time: the PFR length (bi) of the injector region was correlated to the fluidized bed temperature and jet velocity using an Arrhenius expression. In the second part of this work, propane combustion experiments were conducted in the freeboard of a fluidized bed of sand particles at temperatures between 818 K and 923 K and at superficial gas velocity twice the minimum fluidization velocity. The freeboard region was characterized by simultaneous

  18. Bed Bugs

    Science.gov (United States)

    Prevent, identify, and treat bed bug infestations using EPA’s step-by-step guides, based on IPM principles. Find pesticides approved for bed bug control, check out the information clearinghouse, and dispel bed bug myths.

  19. Dynamic simulation of a circulating fluidized bed boiler system part I: Description of the dynamic system and transient behavior of sub-models

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Il; Choi, Sang Min; Yang, Jong In [Dept. of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-12-15

    Dynamic performance simulation of a CFB boiler in a commercial-scale power plant is reported. The boiler system was modeled by a finite number of heat exchanger units, which are sub-grouped into the gas-solid circulation loop, the water-steam circulation loop, and the inter-connected heat exchangers blocks of the boiler. This dynamic model is an extension from the previously reported performance simulation model, which was designed to simulate static performance of the same power plant, where heat and mass for each of the heat exchanger units were balanced for the inter-connected heat exchanger network among the fuel combustion system and the water-steam system. Dynamic performance simulation was achieved by calculating the incremental difference from the previous time step, and progressing for the next time step. Additional discretization of the heat exchanger blocks was necessary to accommodate the dynamic response of the water evaporation and natural circulation as well as the transient response of the metal temperature of the heat exchanger elements. Presentation of the simulation modeling is organized into two parts; system configuration of the model plant and the general approach of the simulation are presented along with the transient behavior of the sub-models in Part I. Dynamic sub-models were integrated in terms of the mass flow and the heat transfer for simulating the CFB boiler system. Dynamic simulation for the open loop response was performed to check the integrated system of the water-steam loop and the solid-gas loop of the total boiler system. Simulation of the total boiler system which includes the closed-loop control system blocks is presented in the following Part II.

  20. Dynamic simulation of a circulating fluidized bed boiler system part I: Description of the dynamic system and transient behavior of sub-models

    International Nuclear Information System (INIS)

    Kim, Seong Il; Choi, Sang Min; Yang, Jong In

    2016-01-01

    Dynamic performance simulation of a CFB boiler in a commercial-scale power plant is reported. The boiler system was modeled by a finite number of heat exchanger units, which are sub-grouped into the gas-solid circulation loop, the water-steam circulation loop, and the inter-connected heat exchangers blocks of the boiler. This dynamic model is an extension from the previously reported performance simulation model, which was designed to simulate static performance of the same power plant, where heat and mass for each of the heat exchanger units were balanced for the inter-connected heat exchanger network among the fuel combustion system and the water-steam system. Dynamic performance simulation was achieved by calculating the incremental difference from the previous time step, and progressing for the next time step. Additional discretization of the heat exchanger blocks was necessary to accommodate the dynamic response of the water evaporation and natural circulation as well as the transient response of the metal temperature of the heat exchanger elements. Presentation of the simulation modeling is organized into two parts; system configuration of the model plant and the general approach of the simulation are presented along with the transient behavior of the sub-models in Part I. Dynamic sub-models were integrated in terms of the mass flow and the heat transfer for simulating the CFB boiler system. Dynamic simulation for the open loop response was performed to check the integrated system of the water-steam loop and the solid-gas loop of the total boiler system. Simulation of the total boiler system which includes the closed-loop control system blocks is presented in the following Part II

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

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

  2. Aggregation capability of a fluidised layer of granular material during treatment of water with high DOC and low alkalinity

    Czech Academy of Sciences Publication Activity Database

    Pivokonský, Martin; Pivokonská, Lenka; Tomášková, Hana

    2008-01-01

    Roč. 8, č. 1 (2008), s. 9-17 ISSN 1606-9749 R&D Projects: GA ČR GA103/07/1016 Institutional research plan: CEZ:AV0Z20600510 Keywords : water treatment * aggregation * fluidised layer * agitation Subject RIV: BK - Fluid Dynamics

  3. CFD-DEM Simulation of Propagation of Sound Waves in Fluid Particles Fluidised Medium

    Directory of Open Access Journals (Sweden)

    H Khawaja

    2016-09-01

    Full Text Available In this work, speed of sound in 2 phase mixture has been explored using CFD-DEM (Computational Fluid Dynamcis - Discrete Element Modelling. In this method volume averaged Navier Stokes, continuity and energy equations are solved for fluid. Particles are simulated as individual entities; their behaviour is captured by Newton's laws of motion and classical contact mechanics. Particle-fluid interaction is captured using drag laws given in literature. The speed of sound in a medium depends on physical properties. It has been found experimentally that speed of sound drops significantly in 2 phase mixture of fluidised particles because of its increased density relative to gas while maintaining its compressibility. Due to the high rate of heat transfer within 2 phase medium as given in Roy et al. (1990, it has been assumed that the fluidised gas-particle medium is isothermal. The similar phenomenon has been tried to be captured using CFD-DEM numerical simulation. The disturbance is introduced and fundamental frequency in the medium is noted to measure the speed of sound for e.g. organ pipe. It has been found that speed of sound is in agreement with the relationship given in Roy et al. (1990. Their assumption that the system is isothermal also appears to be valid.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-01

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

  5. Batch top-spray fluid bed coating: Scale-up insight using dynamic heat- and mass-transfer modelling

    DEFF Research Database (Denmark)

    Hede, Peter Dybdahl; Bach, P.; Jensen, Anker Degn

    2009-01-01

    A mathematical model was developed for batch top-spray fluid bed coating processes based on Ronsse et al. [2007a.b. Combined population balance and thermodynamic modelling of the batch top-spray fluidised bed coating process. Part I-model development and validation. journal of Food Engineering 78......, 296-307; Combined population balance and thermodynamic modelling of the batch top-spray fluidised bed coating process. Part II-model and process analysis. journal of Food Engineering 78, 308-322]. The model is based on one-dimensional discretisation of the fluid bed into a number of well-mixed control......-up principles by comparing simulation results with experimental temperature and humidity data obtained from inorganic salt coating of placebo cores in three pilot fluid bed scales being a 0.5kg small-scale (GEA Aeromatic-Fielder Strea-1), 4kg medium-scale (GEA Niro MP-1) and 24kg large-scale (GEA MP-2...

  6. Lagisza, world's largest CFB boiler, begins commercial operation

    Energy Technology Data Exchange (ETDEWEB)

    Nuortimo, K. [Foster Wheeler, Varkaus (Finland)

    2010-04-15

    Early operating experience with the Lagisza circulating fluidised bed (CFB) boiler in Poland - the world's largest such boiler to date, and also the first one with supercritical steam conditions - has been positive. 3 figs., 4 tabs.

  7. Research report of FY 1997 on the environmentally acceptable coal utilization system introduction support project. Demonstration project of circulating fluidized bed boiler (Jinzhou Coal-Thermal Power Corporation); 1997 nendo seika hokokusho (kankyo chowagata sekitan riyo system donyu shien jigyo). Junkan ryudosho boiler ni kakawaru jissho jigyo (Jinzhou netsuden sokoji)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    To verify the clean coal technology to be diffused in China and consolidate its diffusion basis, demonstration project of circulating fluidized bed boiler was conducted through the cooperation with China which is positive in its introduction. This report describes its characteristics. Coal and limestone are supplied in a lower part of combustion chamber, and are mixed with circulating ash by fluidized air for combustion. Densely fluidized bed the same as the bubbling fluidized bed is formed in the lower part of combustion chamber, which provides excellent stability in ignition and combustion. Particles including ash, char and limestone formed during the combustion are discharged into the cyclone through the convection heat transfer part at the outlet of combustion chamber with the combustion gas flow. Since the gas temperature is lowered to 400 to 500degC at the convection heat transfer part, troubles of the ash circulating system can be prevented. The combustion gas separated from ash at the cyclone is discharged through the heat exchanger and precipitator, and the collected ash is returned to the lower part of combustion chamber. In FY 1997, design, fabrication, procurement/inspection, field survey/meeting, survey of visitors/meeting, and education were carried out. 4 figs., 4 tabs.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  9. Study on the structure and gasification characteristics of selected South African bituminous coals in fluidised bed gasification

    CSIR Research Space (South Africa)

    Oboirien, BO

    2011-04-01

    Full Text Available . The microstructural characteristics of the parent coals and their resultant chars were determined using XRD, FT-IR, Raman and petrographic analysis. The microstructural changes that occurred in the organic (maceral) and the inorganic (mineral) fractions...

  10. Fluidised bed membrane reactor for ultrapure hydrogen production via methane steam reforming: Experimental demonstration and model validation

    NARCIS (Netherlands)

    Patil, C.S.; van Sint Annaland, M.; Kuipers, J.A.M.

    2007-01-01

    Hydrogen is emerging as a future alternative for mobile and stationary energy carriers in addition to its use in chemical and petrochemical applications. A novel multifunctional reactor concept has been developed for the production of ultrapure hydrogen View the MathML source from light hydrocarbons

  11. Fluidised bed membrane reactor for ultrapure hydrogen production via methane steam reforming: Experimental demonstration and model validation

    NARCIS (Netherlands)

    Patil, C.S.; Sint Annaland, van M.; Kuipers, J.A.M.

    2007-01-01

    Hydrogen is emerging as a future alternative for mobile and stationary energy carriers in addition to its use in chemical and petrochemical applications. A novel multifunctional reactor concept has been developed for the production of ultrapure hydrogen (<10 ppm CO) from light hydrocarbons such as

  12. Study on the structure and gasification characteristics of selected South African bituminous coal in fluidised bed gasification

    CSIR Research Space (South Africa)

    Oboirien, BO

    2009-10-01

    Full Text Available that contributed to the higher aromaticity and high burnout level, while for Matla and Duhva with 0.64% and 0.76% Rov values, both the rank and inertinite content playing a role in the carbon conversion with the rank reducing the level of burnout. Table 3...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-01

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

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

    Science.gov (United States)

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

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  17. Fluidized bed reactor for processing particles coated with carbon

    International Nuclear Information System (INIS)

    Marschollek, M.; Simon, W.; Walter, C.

    1978-01-01

    The carbon coating of production returns of these particles first has to be removed before the heavy metal core released can be reprocessed. For reasons of criticality, removal of burnt-up particles downwards must be possible in the fluidized bed reactor even if the reactor diameter is greater than 800 mm, and the material temperatures must not exceed 650 0 C. It consists of an upper cylindrical and a lower conical part, where, according to the invention, the gas distributor heads in the conical part are situated in several planes above one another for the fluidisation and combustion gas and where they are evently distributed over the reactor crossection, so that an even flow profile is achieved over the reactor cross section. (HP) [de

  18. GREENHOUSE GAS EMISSIONS CONTROL BY OXYGEN FIRING IN CIRCULATING FLUIDIZED BED BOILERS: PHASE II--PILOT SCALE TESTING AND UPDATED PERFORMANCE AND ECONOMICS FOR OXYGEN FIRED CFB WITH CO2 CAPTURE

    Energy Technology Data Exchange (ETDEWEB)

    Nsakala ya Nsakala; Gregory N. Liljedahl; David G. Turek

    2004-10-27

    Because fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic CO{sub 2} emissions. In this Phase II study, ALSTOM Power Inc. (ALSTOM) has investigated one promising near-term coal fired power plant configuration designed to capture CO{sub 2} from effluent gas streams for sequestration. Burning fossil fuels in mixtures of oxygen and recirculated flue gas (made principally of CO{sub 2}) essentially eliminates the presence of atmospheric nitrogen in the flue gas. The resulting flue gas is comprised primarily of CO{sub 2}, along with some moisture, nitrogen, oxygen, and trace gases like SO{sub 2} and NO{sub x}. Oxygen firing in utility scale Pulverized Coal (PC) fired boilers has been shown to be a more economical method for CO{sub 2} capture than amine scrubbing (Bozzuto, et al., 2001). Additionally, oxygen firing in Circulating Fluid Bed Boilers (CFB's) can be more economical than in PC or Stoker firing, because recirculated gas flow can be reduced significantly. Oxygen-fired PC and Stoker units require large quantities of recirculated flue gas to maintain acceptable furnace temperatures. Oxygen-fired CFB units, on the other hand, can accomplish this by additional cooling of recirculated solids. The reduced recirculated gas flow with CFB plants results in significant Boiler Island cost savings resulting from reduced component The overall objective of the Phase II workscope, which is the subject of this report, is to generate a refined technical and economic evaluation of the Oxygen fired CFB case (Case-2 from Phase I) utilizing the information learned from pilot-scale testing of this concept. The objective of the pilot-scale testing was to generate detailed technical data needed to establish advanced CFB design requirements and performance when firing coals and

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

    Energy Technology Data Exchange (ETDEWEB)

    Hofbauer, Gerrit Arne

    2017-03-16

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

  20. Heat transfer to immersed horizontal tubes in gas fluidized bed dryers

    Energy Technology Data Exchange (ETDEWEB)

    Jonassen, Ola

    1999-10-01

    The main objective of this study was to construct heat pump fluidized bed dryers of the FHT type with improved dewatering capacity for a given size of the dryer. The use of heat exchangers immersed in the fluidized bed drying chambers is an important part of the FHT (Fluidized Bed High Temperature Heat Pump Dryer) concept. A pilot plant FHT dryer was built and successfully tested on fish meal raw material and seaweed. The plant included two fluidized bed drying chambers with immersed heat exchangers. The gain in water vapor of the drying air through the chambers was increased up to four times that of adiabatic drying. The energy saving concept was retained as a SMER ratio of 3.5 to 4.7 was measured in the same tests. Therefore optimization of the immersed heat exchangers was considered the most important single objective for this work. The optimization study of the heat exchangers was confined to the actual operating conditions for the dryers using: (1) Bubbling gas fluidized beds were used, (2) air as the only type of fluidising gas, (3) beds at atmospheric pressure, (4) bed temperatures below 100 {sup o}C, (5) fluidized particles of Geldart classes B and D, (6) horizontal tube banks for the immersed heat exchanger, and the influence of radiation heat transfer was ignored. The heat transfer study was confined to the fluidized bed side of the heat exchanger surface. It was concluded early in this work that the bubbles play a major role in generating the particle circulation inside the bed and hence also in heat transfer. Publications describing the most important bubble induced mechanisms contributing to high rates of heat transfer were found to be limited. Therefore the first part of this study was aimed at establishing a method for locating and measuring the size and rise velocity of bubbles inside the bed. The method established through this work using differential pressure measurements from two static pressure probes was used later in the study of heat transfer

  1. Heat exchanger support apparatus in a fluidized bed

    Science.gov (United States)

    Lawton, Carl W.

    1982-01-01

    A heat exchanger is mounted in the upper portion of a fluidized combusting bed for the control of the temperature of the bed. A support, made up of tubes, is extended from the perforated plate of the fluidized bed up to the heat exchanger. The tubular support framework for the heat exchanger has liquid circulated therethrough to prevent deterioration of the support.

  2. Fluidized bed heat exchanger utilizing angularly extending heat exchange tubes

    Science.gov (United States)

    Talmud, Fred M.; Garcia-Mallol, Juan-Antonio

    1980-01-01

    A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided and includes a steam drum disposed adjacent the fluidized bed and a series of tubes connected at one end to the steam drum. A portion of the tubes are connected to a water drum and in the path of the air and the gaseous products of combustion exiting from the bed. Another portion of the tubes pass through the bed and extend at an angle to the upper surface of the bed.

  3. Internal dust recirculation system for a fluidized bed heat exchanger

    Science.gov (United States)

    Gamble, Robert L.; Garcia-Mallol, Juan A.

    1981-01-01

    A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided in a heat exchange relation to the bed and includes a steam drum disposed adjacent the bed and a tube bank extending between the steam drum and a water drum. The tube bank is located in the path of the effluent gases exiting from the bed and a baffle system is provided to separate the solid particulate matter from the effluent gases. The particulate matter is collected and injected back into the fluidized bed.

  4. FY 2000 report on the potential survey of the environmental friendly type coal utilization system. Survey for digging up items for the model project on spread type circulating fluid bed boilers in China; 2000 nendo chosa hokokusho. Kankyo chowagata sekitan riyo system kanosei chosa. Chugoku ni okeru fukyugata junkan ryudo yukaboira setsubi model jigyo no anken hakkutsu chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-09-01

    For the purpose of spreading/promoting circulating fluidized bed boilers in China, survey was conducted on the confirmation of effectiveness of implementation of the model project on spread type circulating fluidized bed boilers and the appropriateness of the sites proposed for implementation. As to the model of spread type 35t/h-CFB boilers, local products are more integrated into it, taking cost reduction of equipment and secure performance/quality into consideration, and the wider-ranging technical guidance/transfer are conducted also in design/production. In China, where environmental regulations are not strict, and there are many restrictions on funds, the size of the initial investment is an important element for selection of type. Further, the market is very big, about 200 units/year. It is highly possible to realize the competitive cost level by the quantity production effect by increasing local production. Two companies, Southeast Electrochemical Co. and Fujian Prime Pharmaceutical Group Co., which were proposed as sites are financially good and are achieving substantial results. Both companies are located in the urban area, and therefore, environmental measures should urgently be taken, and PR activities for spread are highly effective. It was confirmed that the companies were fully appropriate as sites proposed for the spread type model project. (NEDO)

  5. Research report of FY 1997 on the environmentally acceptable coal utilization system introduction support project. Follow-up project on circulating fluidized bed boiler introduction (Calaca Batangas Thermal Power Station); 1997 nendo chosa hokokusho. Kankyo chowagata sekitan riyo system donyu shien jigyo (junkan ryudosho boiler ni kakawaru follow up jigyo (Calaca Batangas karyoku hatsudensho))

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    For the follow-up project, to promote the diffusion of results of the clean coal technology (CCT) model projects, experts of circulating fluidized bed boilers were dispatched, to guide and advise for the operation of facilities introduced in these projects. The purpose of these projects is to diffuse the CCTs, and to support the promotion of environmental measures. Some guidance and advice about operation processes, data processing, operation regulation, maintenance, and boiler maintenance works were provided to the Ministry of Energy and Electric Power Corporation of the Philippines. Semirara, Malangas, and Samar coals in the Philippines were used for the tests. The boiler facilities could be operated by Philippine operators themselves. Based on the guidance and advice about operation processes, combustion tests using various Philippine coals were also planned and conducted by themselves. The maintenance techniques were transferred to Philippine operators through the inspection, repair and advice. The Philippine side understood the technologies well, and the circulating fluidized bed boiler technology was independently educated in the Philippines. 23 figs., 16 tabs.

  6. Fluidized-bed nuclear reactor

    International Nuclear Information System (INIS)

    Grimmett, E.S.; Kunze, J.F.

    1975-01-01

    A reactor vessel containing a fluidized-bed region of particulate material including both a neutron-moderating and a fertile substance is described. A gas flow including fissile material passes through the vessel at a sufficient rate to fluidize the particulate material and at a sufficient density to support a thermal fission reaction within the fluidized-bed region. The high-temperature portion of a heat transfer system is located within the fluidized-bed region of the reactor vessel in direct contact with the fluidized particles. Heat released by fission is thereby transferred at an enhanced rate to a coolant circulating within the heat transfer system. Fission products are continuously removed from the gas flow and supplemental fissile material added during the reactor operation. (U.S.)

  7. Fuel gas production from renewable biomass in a circulating fluidized bed as a bases for zero-CO{sub 2} power generation in a combined-cycle power plant; Brenngaserzeugung aus nachwachsenden Biomassen in der zirkulierenden Wirbelschicht als Grundlage fuer eine CO{sub 2}-neutrale Stromerzeugung in einem GUD Kraftwerk

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, J.; Loeffler, J.; Hirschfelder, H. [Lurgi Energie und Umwelt GmbH, Frankfurt am Main (Germany)

    1996-12-31

    A pilot circulating fluidized bed plant in the range of 1.7 MW{sub th} has been operated successfully with fossil fuels, residues, wood bark and wood chips, reet grass and sorghum pellets. Depending on the specifications for product gas and fuel quality, air, oxygen-enriched air or oxygen/steam mixtures are used as gasification agents in the gas generator. (orig) [Deutsch] In einer ZWS-Pilotanlage mit ca. 1.7 MW thermischer Leistung wurden bisher ausser fossilen und Abfallbrennstoffen auch Rindenabfaelle, Holzschnitzel, Schilfgras und Sorghumpellets erfolgreich zur Brenngaserzeugung eingesetzt. Entsprechend den Anforderungen an das Produktgas und der Brennstoffqualitaet wird Luft, sauerstoffangereicherte Luft oder Sauerstoff/Dampfgemische als Vergasungsmittel im ZWS-Gaserzeuger eingesetzt. (orig)

  8. Fuel gas production from renewable biomass in a circulating fluidized bed as a bases for zero-CO{sub 2} power generation in a combined-cycle power plant; Brenngaserzeugung aus nachwachsenden Biomassen in der zirkulierenden Wirbelschicht als Grundlage fuer eine CO{sub 2}-neutrale Stromerzeugung in einem GUD Kraftwerk

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, J; Loeffler, J; Hirschfelder, H [Lurgi Energie und Umwelt GmbH, Frankfurt am Main (Germany)

    1997-12-31

    A pilot circulating fluidized bed plant in the range of 1.7 MW{sub th} has been operated successfully with fossil fuels, residues, wood bark and wood chips, reet grass and sorghum pellets. Depending on the specifications for product gas and fuel quality, air, oxygen-enriched air or oxygen/steam mixtures are used as gasification agents in the gas generator. (orig) [Deutsch] In einer ZWS-Pilotanlage mit ca. 1.7 MW thermischer Leistung wurden bisher ausser fossilen und Abfallbrennstoffen auch Rindenabfaelle, Holzschnitzel, Schilfgras und Sorghumpellets erfolgreich zur Brenngaserzeugung eingesetzt. Entsprechend den Anforderungen an das Produktgas und der Brennstoffqualitaet wird Luft, sauerstoffangereicherte Luft oder Sauerstoff/Dampfgemische als Vergasungsmittel im ZWS-Gaserzeuger eingesetzt. (orig)

  9. FY 2000 report on the survey project on potentiality of the environmental harmony coal utilization system. Potential study of the circulating fluidized bed boiler model project in Vietnam; 2000 nendo kankyo chowagata sekitan riyo system kanosei chosa jigyo hokokusho. Vietnam ni okeru junkan ryudosho boiler model jigyo jisshi kanosei chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    In Vietnam, survey was conducted of the project in which the adoption of circulating fluidized bed boiler (CFB) makes energy conservation and greenhouse effect gas reduction possible. CFB makes a marked decrease in SOx emission possible by using limestone as combustion bed material. As a result of the survey, the thermal power plant was not suitable for the model project due to its large size. However, it was found that two cement plants and one fiber plant having coal-fired boiler were suitable for survey. Nghi Son and Bim Son cement plants are typical cement plants in Vietnam. As a result of the hearing, they were eager to adopt CFB equipment. As to environmental improvement effects, in the thermal power plant with power source loads, emissions of SOx and NOx can be reduced by 79.0% and 72.5%, respectively. Further, in Nam Dinh Textile Company, emissions of SOx and NOx can be reduced by 79.8% and 84.6%, respectively, in case of converting boiler from the existing stoker boiler to CFB boiler. (NEDO)

  10. Investigation of combustion of coal briquettes in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-01

    This paper discusses the results obtained from an experimental combustion work undertaken to investigate the behaviour of multicomponent briquettes, prepared by mixing two different particle sizes of coal and two different types of binder species. single briquettes were burned over a wide range of temperatures in a laboratory scale fluidised bed combustor facility. Nitrogen (NO{sub x}, and N{sub 2}O) and Sulphur (SO{sub 2}) oxides emissions resulting from the combustion of these briquettes were constantly monitored during the time of burning. The levels of O{sub 2}, CO{sub 2} and CO were also recorded during the same period. Experimental results showed that coal particle size influenced burn-out times and emissions levels of some of gaseous species. The hinder type was also found to have a major influence on the emissions of different pollutants.The temperature was observed to significantly influence the extent of the effects of the other operating parameters studied.

  11. Modelling of Devolatilization in Fluidized Bed Combustion

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  12. Process and technological wastes compaction through a fluidized bed incineration process

    International Nuclear Information System (INIS)

    Guiroy, J.J.

    1993-01-01

    The various fluidized bed systems (dense or circulating) are reviewed and the advantages of the circulation fluidized bed are highlighted (excellent combustion performance, clean combustion, large operating range, poly-functionality with regards to waste type, ...). Applications to contaminated graphite (with the problem of ash management) and to plant process wastes (ion exchangers, technological wastes, aqueous effluents); study of the neutralization and chlorine emission

  13. Bioenergy originating from biomass combustion in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

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

  14. Artificial neural network models for biomass gasification in fluidized bed gasifiers

    DEFF Research Database (Denmark)

    Puig Arnavat, Maria; Hernández, J. Alfredo; Bruno, Joan Carles

    2013-01-01

    Artificial neural networks (ANNs) have been applied for modeling biomass gasification process in fluidized bed reactors. Two architectures of ANNs models are presented; one for circulating fluidized bed gasifiers (CFB) and the other for bubbling fluidized bed gasifiers (BFB). Both models determine...

  15. Tests of Bed Agglomeration Tendency Using a Rotating Furnace; Roterugn foer bedoemning av sintringsbenaegenhet

    Energy Technology Data Exchange (ETDEWEB)

    Larfeldt, Jenny; Zintl, Frank [TPS Termiska Processer AB, Nykoeping (Sweden)

    2003-08-01

    Bed sintering is a well known problem in fluidised bed boilers. In order to avoid bed sintering the bed material turn over ratio is high which leads a high consumption of bed material. This work aims at developing and evaluating a method for testing the bed agglomeration tendency of a FB bed material by using a rotating furnace. A rotating furnace has been designed and tests have shown that three temperatures describing the increasing agglomeration tendency can be evaluated; TA when several particles stick to each other and to the crucible wall, TB when half of the material sticks to the wall and TC when almost all the material forms a ball in the crucible. Comparison with bed agglomeration tests has shown that TA is between 80 deg C to 130 deg C lower than the bed agglomeration temperature from fluid bed tests. It is shown that TB is closer to the bed agglomeration temperature and finally that the temperature TC is higher than the bed agglomeration temperature. It is concluded that in the rotating furnace sticking of particles is visualised early, and that this sticking will not cause defluidisation of the bed until more than half of the material in the crucible is sticky. Repeated tests has been performed at a heating rate of 5 deg/minute and a rotating speed of 12 rpm and a furnace inclination of 20 deg was found to give distinct results in the evaluation. The evaluation has shown to be reproducible at lower temperatures. At higher temperatures, around 1,000 deg C, the evaluation was complicated by a poor picture quality which probably can be improved by proper cooling of the camera. It has also been shown that sticking of material in the rotating furnace could be detected at relatively low temperatures of 750 deg C that disappeared at higher temperatures. This is likely to be explained by melting salts that evaporates as temperature increase. At even higher temperatures the sticking reappeared until a ball was formed in the crucible. The latter sticking is

  16. Experimental investigation and mathematical modelling of the combustion of brown coal, refuse and mixed fuels in a circulating fluidized bed combustor; Experimentelle Untersuchung und mathematische Modellierung der Verbrennung von Braunkohle, Abfallstoffen und Mischbrennstoffen in einer zirkulierenden Wirbelschichtfeuerung

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W; Brunne, T; Hiller, A [Technische Univ. Dresden (Germany). Inst. fuer Energietechnik; Albrecht, J [Lurgi Umwelt GmbH, Frankfurt am Main (Germany); Quang, N [Polytechnic Inst., Danang (Viet Nam)

    1998-09-01

    Extensive experiments on combustion of biological materials and residues in fluidized bed combustors and dust combustors have been carried out at the Department of Power Plant Engineering of Dresden University since the early nineties. Particular interest was taken in mixing brown coal with sewage sludge, sugar pulp and waste wood. The experiments were supplemented by modelling in a research project funded jointly by the BMBF and Messrs. Lurgi since early 1997. A combustion cell model designed by Siegen University is being modified for the new mixed fuels, and preliminary investigations were carried out on a batch reactor while the modelling work was continued. (orig.) [Deutsch] An dem Lehrstuhl fuer Kraftwerkstechnik der TU Dresden werden seit Anfang der 90-iger Jahre umfangreiche experimentelle Untersuchungen zur Verbrennung von Bio- und Reststoffen in Wirbelschicht- und Staubfeuerungen durchgefuehrt. Dabei war vor allem die Zufeuerung dieser Stoffe in Waermeerzeugeranlagen auf Braunkohlenbasis von besonderem Interesse. Experimentell konnte nachgewiesen werden, dass sowohl Biobrennstoffe als auch Abfaelle in zirkulierenden Wirbelschichtfeuerungen umweltschonend zur Waermeerzeugung eingesetzt werden koennen. Als Beispiel wird das an Hand von Braunkohle-Klaerschlammgemischen sowie Bagasse- und Holz-Braunkohlegemischen gezeigt. Neben den experimentellen Untersuchungen bietet die Modellierung der Verbrennungsvorgaenge ein geeignetes Mittel um Voraussagen zu anderen Mischungsanteilen sowie anderen geometrischen Abmessungen machen zu koennen. Seit Anfang 1997 wird dazu ein vom BMBF und der Firma Lurgi gefoerdertes Forschungsvorhaben bearbeitet. Ein von der Universitaet Gesamthochschule Siegen fuer die Braunkohleverbrennung konzipiertes Zellenmodell wird auf die neuen Brennstoffgemische erweitert. Da grundsaetzlich andere Stoffzusammensetzungen vorliegen, wurden an einem Batch-Reaktor Voruntersuchungen zum Pyrolyseverhalten der Brennstoffe durchgefuehrt. Erste

  17. Tests with blast furnace slag as bed material in a 12 MW waste fired BFB boiler; Fullskalefoersoek med Hyttsand som baeddmaterial i 12 MW avfallseldad BFB-panna

    Energy Technology Data Exchange (ETDEWEB)

    Eklund, Anders; Oehman, Marcus

    2004-11-01

    A full-scale trial has been performed at Saeverstaverket twin 12 MWth BFB boilers in Bollnaes using Hyttsand (a proprietary blast furnace slag) as bed material. The purpose has been to investigate if Hyttsand can be used as bed material in FB boilers for difficult types of fuels. Used fuel has been municipal waste, recovered wood fuel and different types of bio fuels. The test period was 19 days and nearly 100 tons of Hyttsand was used. The most important conclusions are: Good fluidisation can be achieved with Hyttsand as bed material. Hyttsand can fluidise without any changes in boiler settings. Hyttsand can also be mixed with Baskarpsand (a natural sand with over 90% SiO{sub 2}) and used as bed material without any negative changes to the boiler performance. Bed material make-up rate is reduced with up to 30 % when using Hyttsand compared to using Baskarpsand. Other conclusions are: Bed temperature increased slightly and bed temperature deviation decreased. Emissions was in general not affected, however emissions of SO{sub 2} increased slightly. More deposit containing more sulphur was formed on superheater surfaces when using Hyttsand. The increased amount of sulphur when using Hyttsand could be an effect of higher content of sulphur in the fuel or, which is more likely, that sulphur is released from Hyttsand and forms gaseous sulphurous gases. No significant change in produced amounts of fly-, cyclone- or bottom ash. Hyttsand and Baskarpsand had both similar coatings on their particles and similar agglomeration tendencies. There have been some start-up problems during the trials, including two more severe boiler disturbances, but most of these disturbances can be explained and avoided in the future. Previous investigations in laboratory scale using Hyttsand as bed material when firing different bio fuels have shown the advantage of Hyttsand with its higher resistance against a chemical reaction with alkali in the fuel ash compared to conventional bed materials

  18. Practice Hospital Bed Safety

    Science.gov (United States)

    ... Home For Consumers Consumer Updates Practice Hospital Bed Safety Share Tweet Linkedin Pin it More sharing options ... It depends on the complexity of the bed." Safety Tips CDRH offers the following safety tips for ...

  19. Bed Bugs and Schools

    Science.gov (United States)

    Bed bugs have long been a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. They are successful hitchhikers, and can move from an infested site to furniture, bedding, baggage, boxes, and clothing.

  20. FY 1999 Feasibility study on the environmentally-friendly coal utilization systems. Green Helmet Project (Circulating fluidized bed boiler Zaozhuang, Shangdong Province, China); 1999 nendo kankyo chowagata sekitan riyo system kanosei chosa jigyo seika hokokusho. Green helmet jigyo (junkan ryudosho boiler Chugoku Shangdong sho Zaozhuang)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    The demonstration project is carried out in at Chaili coal mine in Shangdong Province, China for installation of and dissemination activities for circulating fluidized bed boilers to abate sulfur oxide emissions associated with utilization of coal, and the FY 1999 results are reported. The operating conditions were reviewed, and some recommendations were made for improving the operation procedures. Limestone was not used for desulfurization, and furnace temperature tended to increase due to increased size of the fluidizing particles. Therefore, it was recommended to use limestone at the design rate. The boiler was operated at a load exceeding the design level, and it was recommended to limit the load viewed from extending serviceability. The boiler start-up procedure was concretely proposed to use a mixed fuel of wood and coal instead of distillate oil, in order to reduce the start-up cost. The recommendations and design support activities for improving facilities included early stage repair of the damaged refractories. For build up of the ashes in the horizontal heat transfer section, the investigated design charts for improvement by installation of ash-discharging hopper were drawn and proposed. Maintenance-related information was given, including Chinese agencies for obtaining auxiliary facilities. (NEDO)

  1. Combustion of mixed fuels (lignite and sewage sludge) in a pilot model of a circulated fluidized bed - a contribution to the waste disposal and to a combustion with low emissions. Final report; Verbrennung von Mischbrennstoffen (Braunkohle und Klaerschlamm) in einer zirkulierenden Wirbelschichtfeuerung - ein Beitrag zur Abfallentsorgung und zu einer schadstoffarmen Verbrennung. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, W.; Brunne, T.; Girndt, H.; Richter, B.; Kaplonek, M.

    1997-04-01

    Mixed fuels based on dried lignite and sewage sludge were burned in a pilot model with circulated fluidized bed technology. The part of sewage sludge has been varied in the fuel, the different reaction and emission conditions were investigated. In the report were laid emphasis on the primary influence of the waste gas components (CO, NO{sub x}, N{sub 2}O). The author started first searchs to the ash composition and to where about of the heavy metals. In the report are recommendation for the industriel effective combustion with low emissions with sewage sludge/lignite mixded fuel. (orig.) [Deutsch] In einer Pilotanlage mit zirkulierender Wirbelschichtfeuerung wurden unterschiedliche Brennstoffgemsiche aus Trockenbraunkohle und Klaerschlamm verbrannt. Die Anteile am Klaerschlamm wurden variiert und die sich aendernden Reaktions- und Emissionsverhaeltnisse aufgenommen. Schwerpunkt dieser Arbeit war die primaere Beeinflussung der Gasschadstoffe (CO, NO{sub x}, N{sub 2}O). Erste Untersuchungen zur Aschenzusammensetzung und zum Verbleib der Schwermetalle wurden vorgenommen. Empfehlungen fuer die grosstechnische, effektive, schadstoffarme Verbrennung von Klaerschlamm/Braunkohle-Gemischen wurden erarbeitet. (orig.)

  2. Apparatus and method for determining solids circulation rate

    Science.gov (United States)

    Ludlow, J Christopher [Morgantown, WV; Spenik, James L [Morgantown, WV

    2012-02-14

    The invention relates to a method of determining bed velocity and solids circulation rate in a standpipe experiencing a moving packed bed flow, such as the in the standpipe section of a circulating bed fluidized reactor The method utilizes in-situ measurement of differential pressure over known axial lengths of the standpipe in conjunction with in-situ gas velocity measurement for a novel application of Ergun equations allowing determination of standpipe void fraction and moving packed bed velocity. The method takes advantage of the moving packed bed property of constant void fraction in order to integrate measured parameters into simultaneous solution of Ergun-based equations and conservation of mass equations across multiple sections of the standpipe.

  3. Fluidized bed volume reduction of diverse radwastes

    International Nuclear Information System (INIS)

    McFee, J.N.; McConnell, J.W.; Waddoups, D.A.; Gray, M.F.; Harwood, L.E.; Clayton, N.J.; Drown, D.C.

    1981-01-01

    Method and apparatus for a fluidized bed radwaste volume reduction system are claimed. Low level radioactive wastes, combustible solids, ion exchange resins and filter sludges, and liquids, emanating from a reactor facility are introduced separately through an integrated waste influent system into a common fluidized bed vessel where volume reduction either through incineration or calcination occurs. Addition of a substance to the ion exchange resin before incineration inhibits the formation of low-melting point materials which tend to form clinkers in the bed. Solid particles are scrubbed or otherwise removed from the gaseous effluent of the vessel in an off-gas system, before the cooled and cleaned off-gas is released to the atmosphere. Iodine is chemically or physically removed from the off-gas. Otherwise, the only egress materials from the volume reduction system are containerized dry solids and tramp material. The bed material used during each mode may be circulated, cleaned, stored and exchanged from within the bed vessel by use of a bed material handling system. An instrumentation and control system provides operator information, monitors performance characteristics, implements start up and shut down procedures, and initiates alarms and emergency procedures during abnormal conditions

  4. 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)

  5. Chemical Processes Related to Combustion in Fluidised Bed. Report for the period 2002-07-01 to 2004-06-30

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-02-01

    One part of the project was an investigation of the mechanism and kinetics of the absorption of potassium and cadmium in kaolin. Addition of kaolin has been suggested as a method to decrease problems like ash sintering, fouling and corrosion. The results showed that kaolin binds potassium effectively, especially if it is present as chloride or hydroxide. Reducing atmosphere and the presence of water vapour favours the absorption. The products are mainly silicates with low solubility. Cadmium is also absorbed by kaolin in a similar way. In the second part of the project, the chemical forms of some metals present in fly ash from combustion of MSW and bio fuels were studied. The most common Cd-compounds found were sulphate, oxide, chloride and silicate. It was also shown that Cd often is incorporated in calcium minerals, such as calcium silicates, CaO and CaC0{sub 3}, due to the fact that the ions Ca{sup 2+} and Cd{sup 2+} are almost similar in size and charge.

  6. Fluid-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, G.; Schoebotham, N.

    1981-02-01

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

  7. Air gasification of agricultural waste in a fluidized bed gasifier: hydrogen production performance

    Energy Technology Data Exchange (ETDEWEB)

    Wan Ab Karim Ghani, W. A.; Moghadam, R. A.; Mohd Salleh, M. A. [Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Alias, A. B. [Chemical Engineering, Universiti Teknologi MARA Malaysia, 54500 Shah Alam, Selangor (Malaysia)

    2009-07-01

    Recently, hydrogen production from biomass has become an attractive technology for power generation. The main objective pursued in this work is to investigate the hydrogen production potential from agricultural wastes (coconut coir and palm kernel shell) by applying the air gasification technique. An experimental study was conducted using a bench-scale fluidized bed gasifier with 60 mm diameter and 425 mm height. During the experiments, the fuel properties and the effects of operating parameters such as gasification temperatures (700 to 900 {sup o}C), fluidization ratio (2 to 3.33 m/s), static bed height (10 to 30 mm) and equivalence ratio (0.16 to 0.46) were studied. It was concluded that substantial amounts of hydrogen gas (up to 67 mol%) could be produced utilizing agricultural residues such as coconut and palm kernel shell by applying this fluidization technique. For both samples, the rise of temperature till 900 {sup o}C favored further hydrocarbon reactions and allowed an increase of almost 67 mol% in the release of hydrogen. However, other parameters such as fluidising velocity and feed load showed only minor effects on hydrogen yield. In conclusion, agricultural waste can be assumed as an alternative renewable energy source to the fossil fuels, and the environmental pollution originating from the disposal of agricultural residues can be partially reduced. (author)

  8. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    Archie Robertson

    2003-10-29

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the July 1--September 30, 2003 time period.

  9. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2003-01-30

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1--December 31, 2002 time period.

  10. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    Archie Robertson

    2003-07-23

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the April 1--June 30, 2003 time period.

  11. Development of Pressurized Circulating Fluidized Bed Partial Gasification Module (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    A. Robertson

    2003-12-31

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1 - December 31, 2003 time period.

  12. Fluidized bed incinerator development

    International Nuclear Information System (INIS)

    Ziegler, D.L.; Johnson, A.J.

    1976-01-01

    A fluidized bed incinerator is being developed for burning rad contaminated solid and liquid waste materials. In situ neutralization of acid gases by the bed material, catalytic afterburning, and gas filtration are used to produce a clean flue gas without the use of aqueous scrubbing

  13. Design of gamma radiation equipment for studying a bubbling gas fluidized bed. Determination of a radial void fraction profile and bubble velocities in a 0.40 m column

    Energy Technology Data Exchange (ETDEWEB)

    Hoogeveen, M O [Technische Univ. Delft (Netherlands). Lab. voor Fysische Technologie

    1993-12-01

    In this work the possibility of the use of gamma radiation in investigating bubbles in a large three dimensional gas-fluidised bed was examined. A measuring system was designed based upon the absorption of gamma radiation. As high energy (>100 keV) gamma radiation penetrates deeply into matter, it can be used to scan through a gas-solid fluidised bed. The attenuation of a beam of mono-energetic photons is related to the amount of solid particles in the path of the beam. With the gamma absorption technique two parameters can be determined: The void fraction and the bubble velocity. With one narrow beam of gamma radiation a chordal void fraction can be measured in the homogeneous part of the bed. An optimalisation procedure for the void fraction determination led to the choice of Cs-137 as radiation source. This optimalisation procedure concerned minimizing of the standard deviation in the determined chordal void fraction as a function of the energy of gamma radiation. With two narrow parallel beams placed at a distance of 12 cm above each other a bubble velocity can be obtained. A cross-correlation between the two detector responses gives the time shift between the two responses. The system was designed for velocity measurements in the non-homogeneous part of the column. A simulation of the two beam measurement method for an air fluidized bed, 0.40 m in diameter, of polystyrene particles led to the choice of 100 mCi for the source strength for each of the two Cs-137 sources. For a 100 mCi Cs-137 source a shielding of 8 cm of lead is necessary to comply with safety regulations, concerning the use of radioactive materials. A source holder was designed, containing two encapsulated 100 mCi Cs-137 sources, in accordance with the regulations in the licence of the Delft University of Technology for the use of encapsulated sources. (orig.).

  14. Design of gamma radiation equipment for studying a bubbling gas fluidized bed. Determination of a radial void fraction profile and bubble velocities in a 0.40 m column

    International Nuclear Information System (INIS)

    Hoogeveen, M.O.

    1993-12-01

    In this work the possibility of the use of gamma radiation in investigating bubbles in a large three dimensional gas-fluidised bed was examined. A measuring system was designed based upon the absorption of gamma radiation. As high energy (>100 keV) gamma radiation penetrates deeply into matter, it can be used to scan through a gas-solid fluidised bed. The attenuation of a beam of mono-energetic photons is related to the amount of solid particles in the path of the beam. With the gamma absorption technique two parameters can be determined: The void fraction and the bubble velocity. With one narrow beam of gamma radiation a chordal void fraction can be measured in the homogeneous part of the bed. An optimalisation procedure for the void fraction determination led to the choice of Cs-137 as radiation source. This optimalisation procedure concerned minimizing of the standard deviation in the determined chordal void fraction as a function of the energy of gamma radiation. With two narrow parallel beams placed at a distance of 12 cm above each other a bubble velocity can be obtained. A cross-correlation between the two detector responses gives the time shift between the two responses. The system was designed for velocity measurements in the non-homogeneous part of the column. A simulation of the two beam measurement method for an air fluidized bed, 0.40 m in diameter, of polystyrene particles led to the choice of 100 mCi for the source strength for each of the two Cs-137 sources. For a 100 mCi Cs-137 source a shielding of 8 cm of lead is necessary to comply with safety regulations, concerning the use of radioactive materials. A source holder was designed, containing two encapsulated 100 mCi Cs-137 sources, in accordance with the regulations in the licence of the Delft University of Technology for the use of encapsulated sources. (orig.)

  15. Final stage of first super-critical 460 MW CFB boiler construction. First experience

    Energy Technology Data Exchange (ETDEWEB)

    Ostrowski, Waldemar [PKE, Lagisza Power Plant (Poland); Goral, Damian [Foster Wheeler Energia Polska, Sosnowiec (Poland)

    2010-07-01

    Steam boilers with circulating fluidised bed combustion have been advanced in the past years and proved well as large-scale technology. A further step was the development and construction of a boiler with super-critical steam parameters and increased output. In 2002 the Polish utility Poludniowy Koncern Energetyczny SA awarded a contract to Foster Wheeler Energia Oy to erect a fluidised bed boiler for the Lagisza power plant. Construction of the 460 MW plant was started in 2006. The plant has been in commercial operation since 2009. (orig.)

  16. Bed Bugs FAQs

    Science.gov (United States)

    ... Europe. Bed bugs have been found in five-star hotels and resorts and their presence is not ... Health – Division of Parasitic Diseases Email Recommend Tweet YouTube Instagram Listen Watch RSS ABOUT About CDC Jobs ...

  17. Bed Bug Information Clearinghouse

    Science.gov (United States)

    Its purpose is to help states, communities, and consumers in efforts to prevent and control bed bug infestations. Currently includes only reviewed material from federal/state/local government agencies, extension services, and universities.

  18. Particle fuel bed tests

    International Nuclear Information System (INIS)

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H 2 for 12 hours with no visible reaction or weight loss

  19. An experimental study on coolability of a particulate bed with radial stratification or triangular shape

    International Nuclear Information System (INIS)

    Thakre, Sachin; Li, Liangxing; Ma, Weimin

    2014-01-01

    Highlights: • Dryout heat flux of a particulate bed with radial stratification is obtained. • It was found to be dominated by hydrodynamics in the bigger size of particle layer. • Coolability of a particulate bed with triangular shape is investigated. • The coolability is improved in the triangular bed due to lateral ingression of coolant. • Coolability of both beds is enhanced by a downcomer. - Abstract: This paper deals with the results of an experimental study on the coolability of particulate beds with radial stratification and triangular shape, respectively. The study is intended to get an idea on how the coolability is affected by the different features of a debris bed formed in a severe accident of light water reactors. The experiments were performed on the POMECO-HT facility which was constructed to investigate two-phase flow and heat transfer in particulate beds under either top-flooding or bottom-fed condition. A downcomer is designed to enable investigation of the effectiveness of natural circulation driven coolability. Two homogenous beds were also employed in the present study to compare their dryout power densities with those of the radially stratified bed and the triangular bed. The results show that the dryout heat fluxes of the homogeneous beds at top-flooding condition can be predicted by the Reed model. For the radially stratified bed, the dryout heat flux is dominated by two-phase flow in the columns packed with larger particles, and the dryout occurred initially near the boundary between the middle column and a side column. Given the same volume of particles under top-flooding condition, the dryout power density of the triangular bed is about 69% higher than that of the homogenous bed. The coolability of all the beds is enhanced by bottom-fed coolant driven by either forced injection or downcomer-induced natural circulation

  20. An experimental study on coolability of a particulate bed with radial stratification or triangular shape

    Energy Technology Data Exchange (ETDEWEB)

    Thakre, Sachin; Li, Liangxing; Ma, Weimin, E-mail: ma@safety.sci.kth.se

    2014-09-15

    Highlights: • Dryout heat flux of a particulate bed with radial stratification is obtained. • It was found to be dominated by hydrodynamics in the bigger size of particle layer. • Coolability of a particulate bed with triangular shape is investigated. • The coolability is improved in the triangular bed due to lateral ingression of coolant. • Coolability of both beds is enhanced by a downcomer. - Abstract: This paper deals with the results of an experimental study on the coolability of particulate beds with radial stratification and triangular shape, respectively. The study is intended to get an idea on how the coolability is affected by the different features of a debris bed formed in a severe accident of light water reactors. The experiments were performed on the POMECO-HT facility which was constructed to investigate two-phase flow and heat transfer in particulate beds under either top-flooding or bottom-fed condition. A downcomer is designed to enable investigation of the effectiveness of natural circulation driven coolability. Two homogenous beds were also employed in the present study to compare their dryout power densities with those of the radially stratified bed and the triangular bed. The results show that the dryout heat fluxes of the homogeneous beds at top-flooding condition can be predicted by the Reed model. For the radially stratified bed, the dryout heat flux is dominated by two-phase flow in the columns packed with larger particles, and the dryout occurred initially near the boundary between the middle column and a side column. Given the same volume of particles under top-flooding condition, the dryout power density of the triangular bed is about 69% higher than that of the homogenous bed. The coolability of all the beds is enhanced by bottom-fed coolant driven by either forced injection or downcomer-induced natural circulation.

  1. Intestinal circulation during inhalation anesthesia

    International Nuclear Information System (INIS)

    Tverskoy, M.; Gelman, S.; Fowler, K.C.; Bradley, E.L.

    1985-01-01

    This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of 86 Rb and 9-microns spheres labeled with 141 Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001). Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO 2 ) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines

  2. Roadmap for cardiovascular circulation model

    Science.gov (United States)

    Bradley, Christopher P.; Suresh, Vinod; Mithraratne, Kumar; Muller, Alexandre; Ho, Harvey; Ladd, David; Hellevik, Leif R.; Omholt, Stig W.; Chase, J. Geoffrey; Müller, Lucas O.; Watanabe, Sansuke M.; Blanco, Pablo J.; de Bono, Bernard; Hunter, Peter J.

    2016-01-01

    Abstract Computational models of many aspects of the mammalian cardiovascular circulation have been developed. Indeed, along with orthopaedics, this area of physiology is one that has attracted much interest from engineers, presumably because the equations governing blood flow in the vascular system are well understood and can be solved with well‐established numerical techniques. Unfortunately, there have been only a few attempts to create a comprehensive public domain resource for cardiovascular researchers. In this paper we propose a roadmap for developing an open source cardiovascular circulation model. The model should be registered to the musculo‐skeletal system. The computational infrastructure for the cardiovascular model should provide for near real‐time computation of blood flow and pressure in all parts of the body. The model should deal with vascular beds in all tissues, and the computational infrastructure for the model should provide links into CellML models of cell function and tissue function. In this work we review the literature associated with 1D blood flow modelling in the cardiovascular system, discuss model encoding standards, software and a model repository. We then describe the coordinate systems used to define the vascular geometry, derive the equations and discuss the implementation of these coupled equations in the open source computational software OpenCMISS. Finally, some preliminary results are presented and plans outlined for the next steps in the development of the model, the computational software and the graphical user interface for accessing the model. PMID:27506597

  3. Pulsed atmospheric fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

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

  4. Boiler for combustion fuel in a fluidized bed

    Directory of Open Access Journals (Sweden)

    Laković Mirjana S.

    2015-01-01

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

  5. Pebble-bed reactor

    International Nuclear Information System (INIS)

    Lohnert, G.; Mueller-Frank, U.; Heil, J.

    1976-01-01

    A pebble-bed nuclear reactor of large power rating comprises a container having a funnel-shaped bottom forming a pebble run-out having a centrally positioned outlet. A bed of downwardly-flowing substantially spherical nuclear fuel pebbles is positioned in the container and forms a reactive nuclear core maintained by feeding unused pebbles to the bed's top surface while used or burned-out pebbles run out and discharge through the outlet. A substantially conical body with its apex pointing upwardly and its periphery spaced from the periphery of the container spreads the bottom of the bed outwardly to provide an annular flow down the funnel-shaped bottom forming the runout, to the discharge outlet. This provides a largely constant downward velocity of the spheres throughout the diameter of the bed throughout a substantial portion of the down travel, so that all spheres reach about the same burned-out condition when they leave the core, after a single pass through the core area

  6. Microwave circulator design

    CERN Document Server

    Linkhart, Douglas K

    2014-01-01

    Circulator design has advanced significantly since the first edition of this book was published 25 years ago. The objective of this second edition is to present theory, information, and design procedures that will enable microwave engineers and technicians to design and build circulators successfully. This resource contains a discussion of the various units used in the circulator design computations, as well as covers the theory of operation. This book presents numerous applications, giving microwave engineers new ideas about how to solve problems using circulators. Design examples are provided, which demonstrate how to apply the information to real-world design tasks.

  7. The burning of automotive shredder residue (ASR) using fluidized bed technology

    Energy Technology Data Exchange (ETDEWEB)

    Abelha, Pedro; Gulyurtlu, Ibrahim; Lopes, H.; Cabrita, I. [INETI/DEECA, Lisboa (Portugal)

    2005-07-01

    The objective of this work was to demonstrate the feasibility and the environmental performance of FBC technology to burn a fluff fraction of an ASR from a Portuguese vehicle dismantling plant. The combustion studies were carried out on the pilot installation at INETI. The results obtained suggest that the Portuguese ASR has a very high mineral content (70%) and the combustion had to be sustained with the use of an auxiliary fuel (propane); the combustion efficiency was very high; the gaseous pollutants could easily be controlled below the permitted limits and sulphur and chlorine emissions were low. ASR could give rise to fluidising problems due to the accumulation of ashes in the bed; therefore, it is essential that a more efficient metal separation method be used during dismantling process; there was an enrichment of heavy metals (Pb, Cu, Mn and Zn) on ashes retained in the cyclones, specially in the smaller particle size range (less than 10 m); however, the ashes did not have a tendency for leaching.

  8. in Spouted Bed

    Directory of Open Access Journals (Sweden)

    Bronislaw Buczek

    2013-01-01

    Full Text Available Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases.

  9. The Safety of Hospital Beds

    Science.gov (United States)

    Gervais, Pierre; Pooler, Charlotte; Merryweather, Andrew; Doig, Alexa K.; Bloswick, Donald

    2015-01-01

    To explore the safety of the standard and the low hospital bed, we report on a microanalysis of 15 patients’ ability to ingress, move about the bed, and egress. The 15 participants were purposefully selected with various disabilities. Bed conditions were randomized with side rails up or down and one low bed with side rails down. We explored the patients’ use of the side rails, bed height, ability to lift their legs onto the mattress, and ability to turn, egress, and walk back to the chair. The standard bed was too high for some participants, both for ingress and egress. Side rails were used by most participants when entering, turning in bed, and exiting. We recommend that side rails be reconsidered as a means to facilitate in-bed movement, ingress, and egress. Furthermore, single deck height settings for all patients are not optimal. Low beds as a safety measure must be re-evaluated. PMID:28462302

  10. Lagrangian Approach to Study Catalytic Fluidized Bed Reactors

    Science.gov (United States)

    Madi, Hossein; Hossein Madi Team; Marcelo Kaufman Rechulski Collaboration; Christian Ludwig Collaboration; Tilman Schildhauer Collaboration

    2013-03-01

    Lagrangian approach of fluidized bed reactors is a method, which simulates the movement of catalyst particles (caused by the fluidization) by changing the gas composition around them. Application of such an investigation is in the analysis of the state of catalysts and surface reactions under quasi-operando conditions. The hydrodynamics of catalyst particles within a fluidized bed reactor was studied to improve a Lagrangian approach. A fluidized bed methanation employed in the production of Synthetic Natural Gas from wood was chosen as the case study. The Lagrangian perspective was modified and improved to include different particle circulation patterns, which were investigated through this study. Experiments were designed to evaluate the concepts of the model. The results indicate that the setup is able to perform the designed experiments and a good agreement between the simulation and the experimental results were observed. It has been shown that fluidized bed reactors, as opposed to fixed beds, can be used to avoid the deactivation of the methanation catalyst due to carbon deposits. Carbon deposition on the catalysts tested with the Lagrangian approach was investigated by temperature programmed oxidation (TPO) analysis of ex-situ catalyst samples. This investigation was done to identify the effects of particles velocity and their circulation patterns on the amount and type of deposited carbon on the catalyst surface. Ecole Polytechnique Federale de Lausanne(EPFL), Paul Scherrer Institute (PSI)

  11. Apparatus for controlling fluidized beds

    Science.gov (United States)

    Rehmat, A.G.; Patel, J.G.

    1987-05-12

    An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

  12. Fluidized bed calciner

    International Nuclear Information System (INIS)

    Sheely, W.F.

    1986-01-01

    A unique way to convert radioactive scrap into useful nuclear fuel products was developed for the Department of Energy at Hanford. An advanced, fluidized bed calciner is used to convert metallic nitrate scrap or waste solutions into benign, solid and gaseous products. There are broad potential applications of this concept beyond those in the nuclear industry

  13. Nail Bed Injuries

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Nail Bed Injuries Email to a friend * required ...

  14. Bed Bug Myths

    Science.gov (United States)

    Learn the truth about bed bugs, such as how easy they are to see with the naked eye, their preferred habitat, whether they transmit diseases, their public health effects, and whether pesticides are the best way to deal with an infestation.

  15. Pulsed atmospheric fluidized-bed combustor development

    International Nuclear Information System (INIS)

    1992-05-01

    Pulsed atmospheric fluidized-bed combustion (PAFBC) is a unique and innovative coal-fueled technology that has the potential to meet these conditions and provide heat and/or process steam to small industrial, commercial, institutional and residential complexes. The potential of Pulse Atmospheric Fluidized Bed Combustion (PAFBC) technology has been amply demonstrated under the sponsorship of a previous DOE/METC contract (DE-AC21-88MC25069). The environmental performance of a coal-fired laboratory-scale system (1.5 million British Thermal Units per hour) (MMBtu/hr) significantly surpassed that of conventional bubbling and circulating fluidized-bed combustion units (see Table 1 for performance comparison). Prompted by these encouraging results in combustion, sulfur capture, emissions control, and enhanced heat transfer, Island Creek Coal Company (ICC) and Baltimore Thermal Energy Corporation expressed interest in the technology and offered to participate by providing host sites for field testing. EA's have been submitted independently for each of these field test sites. This submission addresses the preliminary testing of the PAFBC unit at Manufacturing and Technology Conversion International's (MTCI) Baltimore, MD facility

  16. Circulation pump mounting

    International Nuclear Information System (INIS)

    Skalicky, A.

    1976-01-01

    The suspension is described of nuclear reactor circulating pumps enabling their dilatation with a minimum reverse force consisting of spacing rods supported with one end in the anchor joints and provided with springs and screw joints engaging the circulating pump shoes. The spacing rods are equipped with side vibration dampers anchored in the shaft side wall and on the body of the circulating pump drive body. The negative reverse force F of the spacing rods is given by the relation F=Q/l.y, where Q is the weight of the circulating pump, l is the spatial distance between the shoe joints and anchor joints, and y is the deflection of the circulating pump vertical axis from the mean equilibrium position. The described suspension is advantageous in that that the reverse force for the deflection from the mean equilibrium position is minimal, dynamic behaviour is better, and construction costs are lower compared to suspension design used so far. (J.B.)

  17. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Science.gov (United States)

    2010-01-01

    ... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that... minimum biobased content is 12 percent and shall be based on the amount of qualifying biobased carbon in..., and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of...

  18. VA National Bed Control System

    Data.gov (United States)

    Department of Veterans Affairs — The VA National Bed Control System records the levels of operating, unavailable and authorized beds at each VAMC, and it tracks requests for changes in these levels....

  19. Getting Rid of Bed Bugs

    Science.gov (United States)

    ... Directory Planning, Budget and Results Jobs and Internships Headquarters Offices Regional Offices Labs and Research Centers Bed ... to be careful in how you select a company. Related Information Collaborative Strategy on Bed Bugs - highlights ...

  20. Seasonal overturning circulation in the Red Sea: 2. Winter circulation

    KAUST Repository

    Yao, Fengchao; Hoteit, Ibrahim; Pratt, Lawrence J.; Bower, Amy S.; Kö hl, Armin; Gopalakrishnan, Ganesh; Rivas, David

    2014-01-01

    The shallow winter overturning circulation in the Red Sea is studied using a 50 year high-resolution MITgcm (MIT general circulation model) simulation with realistic atmospheric forcing. The overturning circulation for a typical year, represented

  1. Pebble Bed Reactor Dust Production Model

    Energy Technology Data Exchange (ETDEWEB)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-09-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.

  2. Pebble Bed Reactor Dust Production Model

    International Nuclear Information System (INIS)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-01-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production

  3. Geomechanics of bedded salt

    International Nuclear Information System (INIS)

    Serata, S.; Milnor, S.W.

    1979-01-01

    Creep data from the literature search is reinterpreted by SGI, resulting in a better understanding of the temperature and stress state dependence of the octahedral creep rate and the octahedral shear strength. The concept of a transition strength between the elastic and the plastic states is in agreement with the data. The elastic and rheological properties of salt are described, and a set of constitutive equations is presented. The dependence of material properties on parameters such as temperature is considered. Findings on the permeability of salt are summarized, and the in-situ behavior of openings in bedded salt is described based on extensive engineering experience. A stress measuring system utilizing a finite element computer code is discussed. Geological factors affecting the stability of salt openings are considered, and the Stress Control Technique for designing stable openings in bedded salt formations is explained

  4. Experimental investigation of an active magnetic regenerative heat circulator applied to self-heat recuperation technology

    International Nuclear Information System (INIS)

    Kotani, Yui; Kansha, Yasuki; Ishizuka, Masanori; Tsutsumi, Atsushi

    2014-01-01

    An experimental investigation into an active magnetic regenerative (AMR) heat circulator based on self-heat recuperation technology, was conducted to evaluate its energy saving potential in heat circulation. In an AMR heat circulator, magnetocaloric effect is applied to recuperate the heat exergy of the process fluid. The recuperated heat can be reused to heat the feed process fluid and realize self-heat recuperation. In this paper, AMR heat circulator has newly been constructed to determine the amount of heat circulated when applied to self-heat recuperation and the energy consumption of the heat circulator. Gadolinium and water was used as the magnetocaloric working material and the process fluid, respectively. The heat circulated amount was determined by measuring the temperature of the process fluid and gadolinium. The net work input for heat circulation was obtained from the magnetizing and demagnetizing forces and the distance travelled by the magnetocaloric bed. The results were compared with the minimum work input needed for heat circulation derived from exergy loss during heat exchange. It was seen that the experimentally obtained value was close to the minimum work input needed for heat circulation. - Highlights: • AMR heat circulator has newly been constructed for experimental evaluation. • Heat circulation in the vicinity of Curie temperature was observed. • Energy consumption of an AMR heat circulator has been measured. • Energy saving for processes near Curie temperature of working material was seen

  5. Bed mixing dryer for high moisture content fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hulkkonen, S; Heinonen, O. [Imatran Voima Oy, Vantaa (Finland)

    1998-12-31

    Bed mixing dryer is a new type of fuel drying technology for fluidized bed combustion. The idea is to extract hot bed material from the fluidized bed and use it as a heat source for drying the fuel. Drying occurs at steam atmosphere which makes it possible to recover the latent heat of evaporation to process. This improves the thermal efficiency of the power plant process considerably, especially in combined heat and power applications. Imatran Voima Oy (IVO) has developed the Bed Mixing Dryer technology since early 1990s. The first pilot plant was built in 1994 to IVO`s Kuusamo peat and wood fired power plant. The capacity of the plant is 6 MW{sub e} and 20 MW of district heat. In Kuusamo the dryer is connected to a bubbling fluidized bed. Since it`s commissioning the dryer has been used successfully for about 3000 hours during the heating season in wintertime. The second application of the technology will be a demonstration project in Oerebro (S). IVO Power Engineering Ltd will supply in 1997 a dryer to Oerebro Energi`s peat, wood and coal fired CHP plant equipped with circulating fluidized bed boiler. The fuel to be dried is sawdust with fuel input of about 60 MW. In Kuusamo the dryer produces 3 MW of additional district heat and in Oerebro 6 MW. The fuels in Kuusamo are peat, saw dust and bark. In addition to the municipal heat production this type of drying technology has its benefits in pulp and paper industry processes. Disposal of paper mill sludges is becoming more difficult and costly which has resulted in need of alternative treatment. Drying of the sludge before combustion in a boiler for power production is an attractive option. At the moment IVO is carrying out several studies to apply the Bed Mixing Dryer in pulp and paper industry processes. Economy of drying the sludge looks promising

  6. Bed mixing dryer for high moisture content fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hulkkonen, S.; Heinonen, O. [Imatran Voima Oy, Vantaa (Finland)

    1997-12-31

    Bed mixing dryer is a new type of fuel drying technology for fluidized bed combustion. The idea is to extract hot bed material from the fluidized bed and use it as a heat source for drying the fuel. Drying occurs at steam atmosphere which makes it possible to recover the latent heat of evaporation to process. This improves the thermal efficiency of the power plant process considerably, especially in combined heat and power applications. Imatran Voima Oy (IVO) has developed the Bed Mixing Dryer technology since early 1990s. The first pilot plant was built in 1994 to IVO`s Kuusamo peat and wood fired power plant. The capacity of the plant is 6 MW{sub e} and 20 MW of district heat. In Kuusamo the dryer is connected to a bubbling fluidized bed. Since it`s commissioning the dryer has been used successfully for about 3000 hours during the heating season in wintertime. The second application of the technology will be a demonstration project in Oerebro (S). IVO Power Engineering Ltd will supply in 1997 a dryer to Oerebro Energi`s peat, wood and coal fired CHP plant equipped with circulating fluidized bed boiler. The fuel to be dried is sawdust with fuel input of about 60 MW. In Kuusamo the dryer produces 3 MW of additional district heat and in Oerebro 6 MW. The fuels in Kuusamo are peat, saw dust and bark. In addition to the municipal heat production this type of drying technology has its benefits in pulp and paper industry processes. Disposal of paper mill sludges is becoming more difficult and costly which has resulted in need of alternative treatment. Drying of the sludge before combustion in a boiler for power production is an attractive option. At the moment IVO is carrying out several studies to apply the Bed Mixing Dryer in pulp and paper industry processes. Economy of drying the sludge looks promising

  7. Coal Bed Methane Primer

    Energy Technology Data Exchange (ETDEWEB)

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  8. Infant's bed climate and bedding in the Japanese home.

    Science.gov (United States)

    Nakamura Ikeda, Rie; Fukai, Kiyoko; Okamoto Mizuno, Kazue

    2012-06-01

    to assess the bed climate of infants in their homes in Japan. descriptive, exploratory, non-experimental research design. the data were collected at the participants' homes under normal circumstances. nineteen healthy infants between the ages of two and five months. Their mothers, who joined a parenting class organised by a maternity clinic in Okayama, Japan, consented to participate in this study. we visited the infants' homes and interviewed their mothers concerning the types and use of bedding. The temperature and relative humidity of the bed climate at the back and foot of the bedding, and in the room were measured every minute for four consecutive days. Differences among the bed climates measured during three seasons (spring, summer, and autumn) were assessed by one-way analysis of variance. The bed temperature was higher for infants than for adults. No significant difference in temperature was noted among the three seasons. The bed temperature was about 36.0°C when waterproof sheets and futon mattresses for children or adult were used. The average relative humidity of the bed climate at the back was highest in summer, followed by that in spring and autumn; the differences were significant. The use of waterproof sheets and futon mattresses for children in summer increased the relative humidity to 80% or more. The use of infant beds, sunoko drainboards, and cotton futon mattresses in summer was effective in reducing the bed humidity. these results suggest that nurse-midwives should advise the parents on comfortable bed climates for their infants, as well as how to select and use bedding for them. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. Particle bed reactor modeling

    Science.gov (United States)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  10. The dynamics of the coronary collateral circulation.

    Science.gov (United States)

    Zimarino, Marco; D'Andreamatteo, Mariangela; Waksman, Ron; Epstein, Stephen E; De Caterina, Raffaele

    2014-04-01

    Coronary collaterals are present at birth, with wide interindividual variation in their functional capacity. These vessels protect jeopardized myocardium, and the number of collaterals and the extent of their coverage are associated with improved survival in patients with coronary heart disease. The collateral circulation is not a permanent set of structures, but undergoes dynamic changes with important consequences for cardioprotection. If a severe atherosclerotic lesion develops in an artery supplying tissue downstream of a total occlusion through collateral blood flow, pressure gradients across the collateral bed change. The result is that some of the collateral flow previously supplying the perfusion territory of the totally occluded artery is redirected to the perfusion territory of the donor artery, thus producing a 'collateral steal'. The collateral circulation can regress once antegrade flow in the main dependent artery is re-established, as occurs following the recanalization of a chronic total occlusion. The clinical benefits of coronary revascularization must be cautiously weighed against the risk of reducing the protective support derived from coronary collaterals. Consequently, pharmacological, gene-based, and cell-based therapeutic attempts have been made to enhance collateral function. Although such approaches have so far yielded no, or modest, beneficial results, the rapidly accruing data on coronary collateral circulation will hopefully lead to new effective therapeutic strategies.

  11. Fluid bed solids heater. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Preuit, L. C.

    1980-01-01

    A solids heater which operates at up to 2000 F was designed, fabricated, installed and operated through checkout at the Morgantown Energy Technology Center at Morgantown, West Virginia. The system, designated the 2000 F Fluid Bed Solids Heater (FBSH) uses a fluidized bed to heat limestone to 600 F and aluminium oxide or silicon carbide to 2000 F and discharges heated solids upon demand. The FBSH with added valve handling and pressurization equipment is known as the Valve Hot Solids Test Unit and is intended for use by the US Department of Energy for testing of valves for severe service applications in coal conversion and utilization processes. The FBSH as designed and supplied by Combustion Power Company includes process equipment, controls, the enclosing building and other associated equipment. In the 600 F range of operation it can circulate limestone through two valve test trains simultaneously on a continuous basis. Only one valve test train is used for 2000 F solids and operation in that range is also continuous. Limestone, crushed to minus 5/16 size, is heated, discharged, and recycled at a maximum average rate of 250 lb/min while aluminum oxide or silicon carbide, No. 8 grit, is circulated at rates up to 167 lb/min. The FBSH control system is designed for automatic operation, and capability is included for external computerized data acquisition and/or supervisory control. An operating and maintenance manual and as-built drawings have been submitted. This report describes the FBSH equipment, its design basis, and its operation. It has been prepared and submitted in fulfillment of Contract Number DIAC05-77ET10499.

  12. Fluidized bed boiler feed system

    Science.gov (United States)

    Jones, Brian C.

    1981-01-01

    A fluidized bed boiler feed system for the combustion of pulverized coal. Coal is first screened to separate large from small particles. Large particles of coal are fed directly to the top of the fluidized bed while fine particles are first mixed with recycled char, preheated, and then fed into the interior of the fluidized bed to promote char burnout and to avoid elutriation and carryover.

  13. The heat transfer mechanisms in fluidized beds; Laemmoensiirtomekanismit leijukerroksessa

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Blomster, A.M.; Kojola, H. [Helsinki Univ. of Technology, Espoo (Finland)

    1996-12-01

    The goal of the research project is to improve the accuracy of the heat transfer correlation in circulating fluidized beds and to define how the heat transfer is distributed in radiation and convection in the different parts of the fluidized bed. This will be carried out by studying the behaviour and heat transfer of the fluidized bed in the boundary layer near the wall. The total and radiative heat transfer as well as the particle concentration will be measured. Based on the data a correlation will be created. Two different measurement systems are used. The particle concentration is measured by a image-analysis system. A video camera and a Super VHS recorder are used to capture live images from the bed. The images are digitized and stored on a PC. The system has been used in previous research projects at our laboratory. In earlier projects all measurements have been carried out in cold environments. In this project the system will be modified for hot environments. The radiative heat transfer is measured by a radiative heat transfer probe connected to a PC via an A/D converter. The probe consists of a heat flow detector which is isolated from the bed by a sapphire window so that only the radiative part of the heat transfer is detected. The probe will be calibrated in a black body oven so that the effect of the conduction and the sapphire window can be separated. (author)

  14. Fluidized bed combustion: mixing and pollutant limitation

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

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

  15. Dryout heat flux and flooding phenomena in debris beds consisting of homogeneous diameter particles

    International Nuclear Information System (INIS)

    Maruyama, Yu; Abe, Yutaka; Yamano, Norihiro; Soda, Kunihisa

    1988-08-01

    Since the TMI-2 accident, which occurred in 1979, necessity of understanding phenomena associated with a severe accident have been recognized and researches have been conducted in many countries. During a severe accident of a light water reactor, a debris bed consisting of the degraded core materials would be formed. Because the debris bed continues to release decay heat, the debris bed would remelt when the coolable geometry is not maintained. Thus the degraded core coolability experiments to investigate the influence of the debris particle diameter and coolant flow conditions on the coolability of the debris bed and the flooding experiments to investigate the dependence of flooding phenomena on the configuration of the debris bed have been conducted in JAERI. From the degraded core coolability experiments, the following conclusions were derived; the coolability of debris beds would be improved by coolant supply into the beds, Lipinski's 1-dimensional model shows good agreement with the measured dryout heat flux for the beds under stagnant and forced flow conditions from the bottom of the beds, and the analytical model used for the case that coolant is fed by natural circulation through the downcomer reproduces the experimental results. And the following conclusions were given from the flooding experiments ; no dependence between bed height and the flooding constant exists for the beds lower than the critical bed height, flooding phenomena of the stratified beds would be dominated by the layer consisting of smaller particles, and the predicted dryout heat flux by the analytical model based on the flooding theory gives underestimation under stagnant condition. (author)

  16. Management bedding : vrijloopstal met composterende bedding van houtsnippers

    NARCIS (Netherlands)

    Boer, de H.C.; Wiersma, M.; Galama, P.J.; Szanto, G.L.

    2015-01-01

    In de vrijloopstal liggen de koeien meestal op een organische bedding en scheiden daar mest (feces en urine) uit. Om de bedding voldoende droog en schoon te houden wordt er regelmatig nieuw strooisel aangevoerd en wordt de toplaag bewerkt. Op basis van onderzoek- en praktijkervaringen tot nu toe

  17. Comparative study between fluidized bed and fixed bed reactors in methane reforming with CO2 and O2 to produce syngas

    International Nuclear Information System (INIS)

    Jing Qiangshan; Lou Hui; Mo Liuye; Zheng Xiaoming

    2006-01-01

    Reforming of methane with carbon dioxide and oxygen was investigated over Ni/MgO-SiO 2 catalysts using fixed bed and fluidized bed reactors. The conversions of CH 4 and CO 2 in a fluidized bed reactor were close to thermodynamic equilibrium. The activity and stability of the catalyst in the fixed bed reactor were lower than that in the fluidized bed reactor due to carbon deposition and nickel sintering. TGA and TEM techniques were used to characterize the spent catalysts. The results showed that a lot of whisker carbon was found on the catalyst in the rear of the fixed bed reactor, and no deposited carbon was observed on the catalysts in the fluidized bed reactor after reaction. It is suggested that this phenomenon is related to a permanent circulation of catalyst particles between the oxygen rich and oxygen free zones. That is, fluidization of the catalysts in the fluidized bed reactor favors inhibiting deposited carbon and thermal uniformity in the reactor

  18. Arctic circulation regimes.

    Science.gov (United States)

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L

    2015-10-13

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. © 2015 The Authors.

  19. Effectiveness of Bed Bug Pesticides

    Science.gov (United States)

    Before EPA allows a bed bug claim on a label, the product must be supported by data showing it will kill bed bugs when applied according to the label. Also consider factors such as extent of infestation, site preparation, and insect life stages.

  20. Design and study of Engineering Test Facility - Helium Circulator

    International Nuclear Information System (INIS)

    Jiang Huijing; Ye Ping; Zhao Gang; Geng Yinan; Wang Jie

    2015-01-01

    Helium circulator is one of the key equipment of High-temperature Gas-cooled Reactor Pebble-bed Module (HTR-PM). In order to simulate most normal and accident operating conditions of helium circulator in HTR-PM, a full scale, rated flow rate and power, engineering test loop, which was called Engineering Test Facility - Helium Circulator (ETF-HC), was designed and established. Two prototypes of helium circulator, which was supported by Active Magnetic Bearing (AMB) or sealed by dry gas seals, would be tested on ETF-HC. Therefore, special interchangeable design was under consideration. ETF-HC was constructed compactly, which consisted of eleven sub-systems. In order to reduce the flow resistance of the circuit, special ducts, elbows, valves and flowmeters were selected. Two stages of heat exchange loops were designed and a helium - high pressure pure water heat exchanger was applied to ensure water wouldn't be vaporized while simulating accident conditions. Commissioning tests were carried out and operation results showed that ETF-HC meets the requirement of helium circulator operation. On this test facility, different kinds of experiments were supposed to be held, including mechanical and aerodynamic performance tests, durability tests and so on. These tests would provide the features and performance of helium circulator and verify its feasibility, availability and reliability. (author)

  1. Empirical closures for particulate debris bed spreading induced by gas–liquid flow

    Energy Technology Data Exchange (ETDEWEB)

    Basso, S., E-mail: simoneb@kth.se; Konovalenko, A.; Kudinov, P.

    2016-02-15

    Highlights: • Experimental study of the debris bed self-leveling phenomenon. • A scaling approach and a non-dimensional model to describe particle flow rate are proposed. • The model is validated against experiments with particles of different properties and at different gas injection conditions. - Abstract: Efficient removal of decay heat from the nuclear reactor core debris is paramount for termination of severe accident progression. One of the strategies is based on melt fragmentation, quenching and cooling in a deep pool of water under the reactor vessel. Geometrical configuration of the debris bed is among the important factors which determine possibility of removing the decay heat from the debris bed by natural circulation of the coolant. For instance, a tall mound-shape debris bed can be non-coolable, while the same debris can be coolable if spread uniformly. Decay heat generates a significant amount of thermal energy which goes to production of steam inside the debris bed. Two-phase flow escaping through the top layer of the bed becomes a source of mechanical energy which can move the particulate debris along the slope of the bed. The motion of the debris will lead to flattening of the bed. Such process is often called “self-leveling” phenomenon. Spreading of the debris bed by the self-leveling process can take significant time, depending on the initial debris bed configuration and other parameters. There is a competition between the time scales for reaching (i) a coolable configuration of the bed, and (ii) onset of dryout and re-melting of the debris. In the previous work we have demonstrated that the rate of particulate debris spreading is determined by local gas velocity and local slope angle of the bed. In this work we develop a scaling approach and a closure for prediction of debris spreading rate based on generalization of available experimental data. We demonstrate that introduced scaling criteria are universal for particles of different

  2. Changes in markers of bone formation and resorption in a bed rest model of weightlessness

    Science.gov (United States)

    Lueken, S. A.; Arnaud, S. B.; Taylor, A. K.; Baylink, D. J.

    1993-01-01

    To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

  3. Corn Drying with Zeolite in The Fluidized Bed Dryer under Medium Temperature

    Directory of Open Access Journals (Sweden)

    Mohamad Djaeni

    2013-08-01

    Full Text Available Drying is an important step to find high quality of corn. Based on Standard of National Industry, populer as SNI, number 01-3920-1995, the corn was well stored at moisture content 14% or below (wet basis. However, conventional corn drying dealed with in-efficient energy process and corn quality degradation. This research evaluated the performance of corn drying assisted by zeolite as moisture adsorbent. In this process, the zeolite and corn were placed in the dryer fluidized by warm air as drying medium under 40 - 50oC. The air evaporated water product from corn, and at same time the zeolite adsorbed moisture in air. So, the relative humidity of air in dryer can be kept low in which enhanced the driving force for drying. Beside that, the moisture adsoprtion by zeolite was exothermic process that can supply the energy for drying or keep the dryer temperature. Thus, the drying rate can be faster. This work foccussed to observe the effect of drying temperature, air velocity, and corn to zeolite ratio on drying time as well as corn quality. As indicators, the drying rate was estimated and the proxymates content such as protein, fat, and carbohydrate content were analyzed. The results showed that compared with conventional fluidised bed dryer, corn drying with zeolite, can speed up drying time as well as improving the constant of drying rate. In addition, the corn proximate nutrition content can be well retained. At operating temperature 40oC, air velocity 9 m.s-1, and zeolite to corn ratio 1:2, the drying time can be 60 minutes shorter compared to that without zeolite.

  4. Protecting Your Home from Bed Bugs

    Science.gov (United States)

    ... your home: Inspect the luggage rack in your hotel room for bed bugs. Check secondhand furniture, beds, ... with Bed Bug Problems Discover. Accessibility EPA Administrator Budget & Performance Contracting Grants January 19, 2017 Web Snapshot ...

  5. Controlled humidity gas circulators

    International Nuclear Information System (INIS)

    Gruner, S.M.

    1981-01-01

    A programmable circulator capable of regulating the humidity of a gas stream over a wide range of humidity is described. An optical dew-point hygrometer is used as a feedback element to control the addition or removal of water vapor. Typical regulation of the gas is to a dew-point temperature of +- 0.2 0 C and to an accuracy limited by the dew-point hygrometer

  6. Fluid circulation control device

    International Nuclear Information System (INIS)

    Benard, Henri; Henocque, Jean.

    1982-01-01

    Horizontal fluid circulation control device, of the type having a pivoting flap. This device is intended for being fitted in the pipes of hydraulic installation, particularly in a bleed and venting system of a nuclear power station shifting radioactive or contaminated liquids. The characteristic of this device is the cut-out at the top of the flap to allow the air contained in the pipes to flow freely [fr

  7. Chaotic hydrodynamics of fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Van der Stappen, M.L.M. [Unit Process and Systems Engineering, Advanced Manufacturing Technology Group, Unilever Research Laboratorium, Vlaardingen (Netherlands)

    1996-12-31

    The major goals of this thesis are: (1) to develop and evaluate an analysis method based on techniques from non-linear chaos theory to characterize the nonlinear hydrodynamics of gas-solids fluidized beds quantitatively; and (2) to determine the dependence of the chaotic invariants on the operating conditions and investigate how the chaos analysis method can be profitably applied to improve scale-up and design of gas-solids fluidized bed reactors. Chaos theory is introduced in chapter 2 with emphasis on analysis techniques for (experimental) time series, known from literature at the start of this work (1990-1991). In chapter 3, the testing of existing and newly developed techniques on both model and fluidized bed data is described. This leads to the development of the chaos analysis method to analyze measured pressure fluctuations time series of a fluidized bed. Following, in chapter 4, this method is tested and all choices for the parameters are evaluated. The influence of the experimental parameters and external disturbances on the measurements and analysis results is discussed and quantified. The result is a chaos measurement and analysis protocol, which is further used in this work. In chapter 5, the applications to fluidized beds are discussed. It is shown that the entropy is a good measure for the characterization of the dynamical behavior of gas-solids bubbling/slugging fluidized beds. Entropy is applied to characterize the influence of the operating conditions, to assess regime transitions and to analyze dimensionless similar beds of different scale. Quantitative design correlations that relate entropy to the operating parameters (including the bed diameter) are described. Finally, it is discussed how the results of this work might be used in scaling up the chaotic dynamics of fluidized beds. The overall conclusions and outlook from this work are presented in chapter 6. 182 refs.

  8. Bed retained products in swept fixed bed (SFB) coal hydropyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Mastral, A.M.; Perez-Surio, M.J. [CSIC, Zaragosa (Spain). Inst. de Carboquimica

    1997-12-31

    The hydropyrolysis of a low rank coal in a swept fixed bed (SFB) reactor is carried out by fixing the hydrogen pressure (40 kg/cm{sup 2}), the hydrogen flow (2 l/min) and the residence time (10 min) at increasing temperatures (400 C, 500 C and 600 C) and coal bed heights (h, 1.5h, 2h, 2.5h and 3h). It is shown that the percentages of tars and char directly depend on the coal bed height and that there is not only a quantitative dependence, but also the height of the coal bed is very important and plays a relevant role on the nature of the conversion products. (orig.)

  9. Bed diameter effects and incipient slugging in gas fluidized beds

    International Nuclear Information System (INIS)

    Agarwal, P.K.

    1986-01-01

    The coalescence and growth of bubble swarms formed at the distributor of a fluidized bed gives rise to lateral as well as vertical distributions of bubble properties. However, existing models employ average bubble properties obtained largely from semi-empirical considerations. In a recent Paper, the author developed a bubble growth model based on a population balance approach. Analytical expressions were derived for the bubble characteristic distributions and averages. However, the model, developed for unconstrained growth, did not take into account the effect of the bed diameter and the possibility of slugging. In this Paper, the model is extended to take these aspects into account. A slugging criterion is also developed which is expected to be valid for the regime where incipient slugging depends on the bed height as well as the region where bed height does not significantly affect minimum slugging conditions

  10. Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

    Science.gov (United States)

    Marquis, G. A.; Roy, A. G.

    2012-02-01

    This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

  11. An experimental study on quenching of a radially stratified heated porous bed

    International Nuclear Information System (INIS)

    Nayak, Arun K.; Sehgal, Bal Raj; Stepanyan, Armen V.

    2006-01-01

    The quenching characteristics of a volumetrically-heated particulate bed composed of radially stratified sand layers were investigated experimentally in the POMECO facility. The sand bed simulates the corium particulate debris bed which is formed when the molten corium released from the vessel fragments in water and deposits on the cavity floor during a postulated severe accident in a light water reactor (LWR). The electrically-heated bed was quenched by water from a water column established over top of it, and later also with water coming from its bottom, which was circulating from the water overlayer through downcomers. A series of experiments were conducted to reveal the effects of the size of downcomers, and their locations in the bed, on the quenching characteristics of the radially stratified debris beds. The downcomers were found to significantly increase the bed quenching rate. To simulate the non-condensable gases generated during the MCCI, air and argon were injected from the bottom of the bed at different flow rates. The effects of gas flow rate and its properties on the quenching behaviour were observed. The results indicate that the non-condensable gas flows reduce the quenching rate significantly. The gas properties also affect the quenching characteristics

  12. The heat transfer mechanisms in fluidized beds; Laemmoensiirtomekanismit leijukerroksessa

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Blomster, A.M.; Kojola, H. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Energy Technology and Environmental Protection

    1997-10-01

    The goal of the research project is to improve the accuracy of the heat transfer correlation in circulating fluidized beds and to define how the heat transfer is distributed in radiation and convection in the different parts of the fluidized bed. This will be carried out by studying the behaviour and the heat transfer of the fluidized bed in the boundary layer near the wall. During the project the concentration and the velocity of the sand particles are measured. The particle concentration and the particle velocity are measured by an image analysis system. A video camera and a Super VHS recorder are used to capture live images from the bed. The images are digitized and stored on a PC. The measured particle concentration was at highest slightly over 20 % on the straight wall. As expected, the velocity of the fluidizing gas had the most important role on the particle concentration. The experimental studies of the particle velocity were started last autumn 1996. The velocities of the particles were measured by using a multiple exposure technique. Afterwards the images captured were analyzed by performing a Fourier transform analysis. So far the results have been encouraging and the analyzing work will be ended this spring. (orig.)

  13. Preliminary results from initial in-pile debris bed experiments

    International Nuclear Information System (INIS)

    Rivard, J.B.

    1977-01-01

    An accident in a liquid metal fast breeder reactor (LMFBR) in which molten core material is suddenly quenched with subcooled liquid sodium could result in extensive fragmentation and dispersal of fuel as subcritical beds of frozen particulate debris within the reactor vessel. Since this debris will continue to generate power due to decay of retained fission products, containment of the debris is threatened if the generated heat is not removed. Therefore, the initial safety question is the capacity which debris beds may have for transfer of the decay heat to overlying liquid sodium by natural processes--i.e., without the aid of forced circulation of the coolant. Up to the present time, all experiments on debris bed behavior either have used substitute materials (e.g., sand and water) or have employed actual materials, but atypical heating methods. Increased confidence in the applicability of debris bed simulations is afforded if the heat is generated within the fuel component of the appropriate fast reactor materials. The initial series of in-pile tests reported on herein constitutes the first experiments in which the internal heating mode has been produced in particulate oxide fuel immersed in liquid sodium. Fission heating of the fully-enriched UO 2 in the experiment while it is contained within Sandia Laboratories Annular Core Pulse Reactor (ACPR), operating in its steady-state mode, approximates the decay heating of debris. Preliminary results are discussed

  14. Simulation of biomass-steam gasification in fluidized bed reactors: Model setup, comparisons and preliminary predictions.

    Science.gov (United States)

    Yan, Linbo; Lim, C Jim; Yue, Guangxi; He, Boshu; Grace, John R

    2016-12-01

    A user-defined solver integrating the solid-gas surface reactions and the multi-phase particle-in-cell (MP-PIC) approach is built based on the OpenFOAM software. The solver is tested against experiments. Then, biomass-steam gasification in a dual fluidized bed (DFB) gasifier is preliminarily predicted. It is found that the predictions agree well with the experimental results. The bed material circulation loop in the DFB can form automatically and the bed height is about 1m. The voidage gradually increases along the height of the bed zone in the bubbling fluidized bed (BFB) of the DFB. The U-bend and cyclone can separate the syngas in the BFB and the flue gas in the circulating fluidized bed. The concentration of the gasification products is relatively higher in the conical transition section, and the dry and nitrogen-free syngas at the BFB outlet is predicted to be composed of 55% H 2 , 20% CO, 20% CO 2 and 5% CH 4 . Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Better backs by better beds?

    DEFF Research Database (Denmark)

    Bergholdt, Kim; Fabricius, Rasmus N; Bendix, Tom

    2008-01-01

    mattresses have a positive effect on LBP, and especially a hard mattress is commonly believed to have a positive effect. METHODS: One hundred sixty CLBP patients were randomized to 1 of 3 groups, having a mattress/bed mounted in their sleeping room for 1 month. The beds were: (1) waterbed (Akva), (2) body......-conforming foam mattress (Tempur), and (3) a hard mattress (Innovation Futon). At baseline and after 4 weeks, a blinded observer interviewed the patients on LBP levels (0-10), daily function (activities of daily living, 0-30), and on the amount of sleeping hours/night. RESULTS: Because of dropout of 19 patients...... using the probably most relevant "worst case" data. There were no relevant difference between the effects of the water bed and the foam bed. CONCLUSION: The Waterbed and foam mattress' did influence back symptoms, function and sleep more positively as apposed to the hard mattress, but the differences...

  16. Top Ten Bed Bug Tips

    Science.gov (United States)

    ... Directory Planning, Budget and Results Jobs and Internships Headquarters Offices Regional Offices Labs and Research Centers Bed ... you hire an expert, be sure it’s a company with a good reputation and request that it ...

  17. Torsion testing of bed joints

    DEFF Research Database (Denmark)

    Hansen, Klavs Feilberg; Pedersen, Carsten Mørk

    2008-01-01

    This paper describes a simple test method for determining the torsion strength of a single bed joint between two bricks and presents results from testing using this test method. The setup for the torsion test is well defined, require minimal preparation of the test specimen and the test can...... be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....

  18. Sea bed mapping and inspection

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The conference has 24 presentations on the topics: Sea bed mapping, inspection, positioning, hydrography, marine archaeology, remote operation vehicles and computerized simulation technologies, oil field activities and plans, technological experiences and problems. (tk)

  19. Pipe Decontamination Involving String-Foam Circulation

    International Nuclear Information System (INIS)

    Turchet, J.P.; Estienne, G.; Fournel, B.

    2002-01-01

    Foam applications number for nuclear decontamination purposes has recently increased. The major advantage of foam decontamination is the reduction of secondary liquid wastes volumes. Among foam applications, we focus on foam circulation in contaminated equipment. Dynamic properties of the system ensures an homogeneous and rapid effect of the foam bed-drifted chemical reagents present in the liquid phase. This paper describes a new approach of foam decontamination for pipes. It is based on an alternated air and foam injections. We called it 'string-foam circulation'. A further reduction of liquid wastes is achieved compared to continuous foam. Secondly, total pressure loss along the pipe is controlled by the total foam length in the pipe. It is thus possible to clean longer pipes keeping the pressure under atmospheric pressure value. This ensures the non dispersion of contamination. This study describes experimental results obtained with a neutral foam as well with an acid foam on a 130 m long loop. Finally, the decontamination of a 44 meters pipe is presented. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  1. Dispersion of Bed Load Particles

    OpenAIRE

    SAWAI, Kenji

    1987-01-01

    The motion of bed load particles is so irregular that they disperse remarkably with time.In this study, some flume tests using painted tracer particles were carried out, in which thedispersive property of tracers changed variously with sediment feed rate.In analysing this process, a stochastic simulation model is proposed where it is discussedabout the degree of exposure of individual particle near the bed surface and about the variationof its pick up rate. The exponential distribution of ste...

  2. Graphite beds for coolant filtration at high temperature

    International Nuclear Information System (INIS)

    Heathcock, R.E.; Lacy, C.S.

    1978-01-01

    High temperature filtration will be provided for new Ontario Hydro CANDU heat transport systems. Filtration has been shown to effectively reduce the concentration of circulating corrosion products in our heat transport systems, hence, minimizing the processes of activity transport. This paper will present one option we have for this application; Deep Bed Granular Graphite Filters. The filter system is described by discussing pertinent aspects of its development programme. The compatibility of the filter and the heat transport coolant are demonstrated by results from loop tests, both out- and in-reactor, and by subsequent results from a large filter installation in the NPD NGS heat transport system. (author)

  3. Pulsed atmospheric fluidized bed combustion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

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

  4. Graphite waste incineration in a fluidized bed

    International Nuclear Information System (INIS)

    Guiroy, J.J.

    1996-01-01

    French gas-cooled reactors belonging to the Atomic Energy Commission (CEA), Electricite de France (EDF), Hifrensa (Spain), etc., commissioned between the 1950s and 1970s, have generated large quantities of graphite wastes, mainly in the form of spent fuel sleeves. Furthermore, some of these reactors scheduled for dismantling in the near future (such as the G2 and G3 reactors at Marcoule) have cores consisting of graphite blocks. Consequently, a fraction of the contaminated graphite, amounting to 6000 t in France for example, must be processed in the coming years. For this processing, incineration using a circulating fluidized bed combustor has been selected as a possible solution and validated. However, the first operation to be performed involves recovering this graphite waste, and particularly, first of all, the spent fuel sleeves that were stored in silos during the years of reactor operation. Subsequent to the final shutdown of the Spanish gas-cooled reactor unit, Vandellos 1, the operating utility Hifrensa awarded contracts to a Framatome Iberica SA/ENSA consortium for removing, sorting, and prepackaging of the waste stored in three silos on the Vandellos site, essentially graphite sleeves. On the other hand, a program to validate the Framatome fluidized bed incineration process was carried out using a prototype incinerator installed at Le Creusot, France. The validation program included 22 twelve-hour tests and one 120-hour test. Particular attention was paid to the safety aspects of this project. During the performance of the validation program, a preliminary safety assessment was carried out. An impact assessment was performed with the help of the French Institute for Protection and Nuclear Safety, taking into account the preliminary spectra supplied by the CEA and EDF, and the activities of the radionuclides susceptible of being released into the atmosphere during the incineration. (author). 4 refs, 11 figs, 1 tab

  5. Radiology of liver circulation

    International Nuclear Information System (INIS)

    Hermine, C.L.

    1985-01-01

    This book proposes that careful evaluation of the arterioportogram is the cornerstone in assessing portal flow obstruction, being the most consistent of all observations including liver histology, portal venous pressure, size and number of portosystemic collaterals, and wedged hepatic venous pressure. Very brief chapters cover normal hepatic circulation and angiographic methods. Contrast volumes and flow rates for celiac, hepatic, and superior mesenteric injection are given, with the timing for venous phase radiographs. In the main body of the text, portal obstruction is divided very simply into presinusoidal (all proximal causes) and postsinusoidal (all distal causes, including Budd-Chiari). Changes are discussed regarding the splenic artery and spleen; hepatic artery and its branches; portal flow rate and direction; and arterioportal shunting and portosystemic collateral circulation in minimal, moderate, severe, and very severe portal obstruction and in recognizable entities such as prehepatic portal and hepatic venous obstructions. The major emphasis in this section is the recognition and understanding of flow changes by which level and severity of obstruction are assessed (not simply the anatomy of portosystemic collateral venous flow). Excellent final chapters discuss the question of portal hypertension without obstruction, and the contribution of arterioportography to the treatment of portal hypertension, again with an emphasis on hemodynamics before and after shunt surgery. There is a fascinating final chapter on segmental intrahepatic obstruction without portal hypertension that explains much of the unusual contrast enhancement sometimes seen in CT scanning of hepatic mass lesions

  6. Circulation of Stars

    Science.gov (United States)

    Boitani, P.

    2016-01-01

    Since the dawn of man, contemplation of the stars has been a primary impulse in human beings, who proliferated their knowledge of the stars all over the world. Aristotle sees this as the product of primeval and perennial “wonder” which gives rise to what we call science, philosophy, and poetry. Astronomy, astrology, and star art (painting, architecture, literature, and music) go hand in hand through millennia in all cultures of the planet (and all use catasterisms to explain certain phenomena). Some of these developments are independent of each other, i.e., they take place in one culture independently of others. Some, on the other hand, are the product of the “circulation of stars.” There are two ways of looking at this. One seeks out forms, the other concentrates on the passing of specific lore from one area to another through time. The former relies on archetypes (for instance, with catasterism), the latter constitutes a historical process. In this paper I present some of the surprising ways in which the circulation of stars has occurred—from East to West, from East to the Far East, and from West to East, at times simultaneously.

  7. Development of environmental friendly lost circulation material from banana peel

    Science.gov (United States)

    Sauki, Arina; Hasan, Nur â.€˜Izzati; Naimi, Fardelen Binti Md; Othman, Nur Hidayati

    2017-12-01

    Loss of expensive mud could lead to major financial problem in executing a drilling project and is one of the biggest problems that need to be tackled during drilling. Synthetic Based Mud (SBM) is the most stable state of the art drilling mud used in current drilling technologies. However, the problem with lost circulation is still inevitable. The focus of this project is to develop a new potential waste material from banana peel in order to combat lost circulation in SBM. Standard industrial Lost Circulation Material (LCM) is used to compare the performance of banana peel as LCM in SBM. The effects of different sizing of banana peels (600 micron, 300 micron and 100 micron) were studied on the rheological and filtration properties of SBM and the bridging performance of banana peel as LCM additive. The tests were conducted using viscometer, HTHP filter press and sand bed tester. Thermal analysis of banana peel was also studied using TGA. According to the results obtained, 300 and 100 micron size of banana peel LCM exhibited an improved bridging performance by 65% as compared to industrial LCM. However, banana peel LCM with the size of 600 micron failed to act as LCM due to the total invasion of mud into the sand bed.

  8. Utility of Recycled Bedding for Laboratory Rodents

    OpenAIRE

    Miyamoto, Toru; Li, Zhixia; Kibushi, Tomomi; Okano, Shinya; Yamasaki, Nakamichi; Kasai, Noriyuki

    2009-01-01

    Animal facilities generate a large amount of used bedding containing excrement as medical waste. We developed a recycling system for used bedding that involves soft hydrothermal processing. In this study, we examined the effects of bedding type on growth, hematologic and serum biochemical values, and organ weights of female and male mice reared on either recycled or fresh bedding from 3 to 33 wk of age. Neither growth nor physiology differed between mice housed on recycled bedding compared wi...

  9. Fluid bed porosity equation for an inverse fluidized bed bioreactor with particles growing biofilm

    International Nuclear Information System (INIS)

    Campos-Diaz, K. E.; Limas-Ballesteros, R.

    2009-01-01

    Fluid Bed Bioreactor performance is strongly affected by bed void fraction or bed porosity fluctuations. Particle size enlargement due to biofilm growth is an important factor that is involved in these variations and until now there are no mathematical equations that consider biofilm growth. In this work a mathematical equation is proposed to calculate bed void fraction in an inverse fluid bed bioreactor. (Author)

  10. Circulation Systems Past and Present

    Directory of Open Access Journals (Sweden)

    Maurice J. Freedman

    1981-01-01

    Full Text Available A review of the development of circulation systems shows two areas of change. The librarian's perception of circulation control has shifted from a broad service orientation to a narrow record-keeping approach and recently back again. The technological development of circulation sys-tems has evolved from manual systems to the online systems of today. The trade-offs and deficiencies of earlier systems in relation to the comprehensive services made possible by the online computer are detailed.

  11. Experimental study of the drying in dense fluidized beds of a synthetic mud coated with support particulates; Etude experimentale du sechage en lit fluidise dense d'une boue synthetique enrobee sur des particules supports

    Energy Technology Data Exchange (ETDEWEB)

    Gode, C.; Shakourzadeh, K. [Universite de Technologie de Compiegne, L.G.P.I., 60 (France)

    2001-07-01

    This article presents the results of an experimental study of a new drying process for muddy materials and based on the fluidization technique. The granular phase has been obtained by the coating with mud of a porous mineral support, inert and recyclable in the process. Activated porous particulates of alumina (2-5 mm) have been chosen because of their heat transfer properties. A first part of the experimental study concerns the drying process. The second part concerns the attrition and elutriation mechanisms. The experimental measurements have been performed with a laboratory fluidized column (internal diameter = 150 mm) and with a fluidized column (internal diameter = 400 mm) from a semi-industrial facility. The air velocity and the drying temperature are the main adjustment parameters. The working temperatures have been fixed between 20 and 150 deg. C. (J.S.)

  12. Clinical physiology of bed rest

    Science.gov (United States)

    Greenleaf, John E.

    1993-01-01

    Maintenance of optimal health in humans requires the proper balance between exercise, rest, and sleep as well as time in the upright position. About one-third of a lifetime is spent sleeping; and it is no coincidence that sleeping is performed in the horizontal position, the position in which gravitational influence on the body is minimal. Although enforced bed rest is necessary for the treatment of some ailments, in some cases it has probably been used unwisely. In addition to the lower hydrostatic pressure with the normally dependent regions of the cardiovascular system, body fuid compartments during bed rest in the horizontal body position, and virtual elimination of compression on the long bones of the skeletal system during bed rest (hypogravia), there is often reduction in energy metabolism due to the relative confinement (hypodynamia) and alteration of ambulatory circadian variations in metabolism, body temperature, and many hormonal systems. If patients are also moved to unfamiliar surroundings, they probably experience some feelings of anxiety and some sociopsychological problems. Adaptive physiological responses during bed rest are normal for that environment. They are attempts by the body to reduce unnecessary energy expenditure, to optimize its function, and to enhance its survival potential. Many of the deconditioning responses begin within the first day or two of bed rest; these early responses have prompted physicians to insist upon early resumption of the upright posture and ambulation of bedridden patients.

  13. The ocean circulation inverse problem

    National Research Council Canada - National Science Library

    Wunsch, C

    1996-01-01

    .... This book addresses the problem of inferring the state of the ocean circulation, understanding it dynamically, and even forecasting it through a quantitative combination of theory and observation...

  14. Particle Bed Reactor scaling relationships

    International Nuclear Information System (INIS)

    Slovik, G.; Araj, K.; Horn, F.L.; Ludewig, H.; Benenati, R.

    1987-01-01

    Scaling relationships for Particle Bed Reactors (PBRs) are discussed. The particular applications are short duration systems, i.e., for propulsion or burst power. Particle Bed Reactors can use a wide selection of different moderators and reflectors and be designed for such a wide range of power and bed power densities. Additional design considerations include the effect of varying the number of fuel elements, outlet Mach number in hot gas channel, etc. All of these variables and options result in a wide range of reactor weights and performance. Extremely light weight reactors (approximately 1 kg/MW) are possible with the appropriate choice of moderator/reflector and power density. Such systems are very attractive for propulsion systems where parasitic weight has to be minimized

  15. Lignite air-steam gasification in the fluidized bed of iron-containing slag catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, B.N.; Shchipko, M.L.; Golovin, Yu. [Inst. of Chemistry of Natural Organic Materials, Academgorodok, Krasnoyarsk (Russian Federation)

    1995-12-01

    The influence of fluidized bed of iron-containing slag particles on air-steam gasification of powdered Kansk-Achinsk lignite in entrained flow was studied in pilot installation with productivity about 60 kg per hour. Slag of Martin process and boiler slag were used as catalytic active materials until their complete mechanical attrition. Two following methods of catalytic gasification of lignite were compared: the partial gasification in stationary fluidized bed of slag particles with degree of fuel conversion 40-70% and complete gasification in circulating bed of slag particles. In the first case only the most reactive part of fuel is gasified with the simultaneously formation of porous carbon residue with good sorption ability. It was found the catalytic fluidized bed improves heat transfer from combustion to reduction zone of gas-generator and increases the rate of fuel conversion at the temperature range 900-1000{degrees}C. At these temperatures the degree of conversion is depended considerably on the duration time of fuel particles in the catalytic fluidized bed. The influence of catalytic fluidized bed height and velocity of reaction mixture on the temperature profiles in the gas-generator was studied. The optimal relationship was found between the fluidized bed height and velocity of flow which makes possible to produce the gas with higher calorific value at maximum degree of fuel conversion.

  16. Prediction of bed level variations in nonuniform sediment bed channel

    Indian Academy of Sciences (India)

    B R Andharia

    2018-04-12

    Apr 12, 2018 ... A fully-coupled 1D mobile-bed model (CAR-. ICHAR) was introduced ...... for sediment trap, water level sensor, tail gate operated by lever arm at .... materials were brought back to upstream to feed the same through sediment ...

  17. The fixed bed nuclear reactor concept

    International Nuclear Information System (INIS)

    Sahin, S.; Sefidvash, F.

    2007-01-01

    The core of a water moderated Fixed Bed Nuclear Reactor (FBNR), possessing, for instance, an electrical power of 40 MW, consists of 1.35 million fuel pellets (9.5 t) with a diameter of 1.5 cm each. The low enriched uranium fuel is made of TRISO type microspheres used in the HTGR, embedded in a graphite matrix and cladded by a shell of 1 mm SiC. Under any thinkable operational condition the fuel temperature will be below 400 C whereas its stability limit is at about 1600 C. The first characteristic of the FBNR is, therefore, its robust fuel under relatively 'cold' operating conditions and - due to the outer SiC - shell layer - the freedom from any hydrogen production. To operate the reactor the fuel pellets are pumped by a flow of water from below into the core regions where they form a stable fixed bed of about 4 cubic meter and become critical for energy production heating the outlet water to about 330 C (at 160 bar) which feeds a steam generator. The new safety feature is now the following: In case of any abnormity (e.g. external power failure, overheating etc.) the circulating pump stops and - due to gravity - the fuel pellets fall automatically out of the core region into a helical 'fuel chamber' underneath the core where their decay heat is transferred passively by natural circulation to a water tank housing the fuel chamber. The safety principle, applied here, is: The loss of an active component (circulating pump) induces a self-controlled, passively working shut-down manoeuvre accompanied by a foolproof decay heat removal without any emergency power system or any human interaction. The fuel chamber is sealed and is transported as the only reactor component to and from the reactor site. There is no possibility to irradiate fertile fuel, too. For a long-life core (larger than a 10 years cycle time) the fuel can either be poisoned by gadolinium-oxide or by a piston type core limiter adjusting the height and controlling thereby the number of the fuel pellets in

  18. Sino-Danish Brain Circulation

    DEFF Research Database (Denmark)

    Bertelsen, Rasmus Gjedssø; Du, Xiangyun; Søndergaard, Morten Karnøe

    2014-01-01

    China is faced with urgent needs to develop an economically and environmentally sustainable economy based on innovation and knowledge. Brain circulation and research and business investments from the outside are central for this development. Sino-American brain circulation and research...... and investment by overseas researchers and entrepreneurs are well described. In that case, the US is the center of global R&D and S&T. However, the brain circulation and research and investments between a small open Scandinavian economy, such as Denmark, and the huge developing economy of China are not well...... understood. In this case, Denmark is very highly developed, but a satellite in the global R&D and S&T system. With time and the growth of China as a R&D and S&T power house, both Denmark and China will benefit from brain circulation between them. Such brain circulation is likely to play a key role in flows...

  19. Apparatus and process for controlling fluidized beds

    Science.gov (United States)

    Rehmat, Amirali G.; Patel, Jitendra G.

    1985-10-01

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  20. Bed erosion control at 60 degree river confluence using vanes

    Science.gov (United States)

    Wuppukondur, Ananth; Chandra, Venu

    2017-04-01

    Confluences are common occurrences along natural rivers. Hydrodynamics at the confluence is complex due to merging of main and lateral flows with different characteristics. Bed erosion occurs at the confluence due to turbulence and also secondary circulation induced by centrifugal action of the lateral flow. The eroded sediment poses various problems in the river ecosystem including river bank failure. Reservoirs are majorly affected due to sediment deposition which reduces storage capacity. The bed erosion also endangers stability of pipeline crossings and bridge piers. The aim of this experimental study is to check the performance of vanes in controlling bed erosion at the confluence. Experiments are performed in a 600 confluence mobile bed model with a non-uniform sediment of mean particle size d50 = 0.28mm. Discharge ratio (q=ratio of lateral flow discharge to main flow discharge) is maintained as 0.5 and 0.75 with a constant average main flow depth (h) of 5cm. Vanes of width 0.3h (1.5cm) and thickness of 1 mm are placed along the mixing layer at an angle of 150, 300 and 600(with respect to main flow) to perform the experiments. Also, two different spacing of 2h and 3h (10cm and 15cm) between the vanes are used for conducting the experiments. A digital point gauge with an accuracy of ±0.1mm is used to measure bed levels and flow depths at the confluence. An Acoustic Doppler Velocitimeter (ADV) with a frequency of 25Hz and accuracy of ±1mm/s is used to measure flow velocities. Maximum scour depth ratio Rmax, which is ratio between maximum scour depth (Ds) and flow depth (h), is used to present the experimental results.From the experiments without vanes, it is observed that the velocities are increasing along the mixing layer and Rmax=0.82 and 1.06, for q=0.5 and 0.75, respectively. The velocities reduce with vanes since roughness increases along the mixing layer. For q=0.5 and 0.75, Rmax reduces to 0.62 and 0.7 with vanes at 2h spacing, respectively. Similarly

  1. Natural Circulation with Boiling

    Energy Technology Data Exchange (ETDEWEB)

    Mathisen, R P

    1967-09-15

    A number of parameters with dominant influence on the power level at hydrodynamic instability in natural circulation, two-phase flow, have been studied experimentally. The geometrical dependent quantities were: the system driving head, the boiling channel and riser dimensions, the single-phase as well as the two phase flow restrictions. The parameters influencing the liquid properties were the system pressure and the test section inlet subcooling. The threshold of instability was determined by plotting the noise characteristics in the mass flow records against power. The flow responses to artificially obtained power disturbances at instability conditions were also measured in order to study the nature of hydrodynamic instability. The results presented give a review over relatively wide ranges of the main parameters, mainly concerning the coolant performance in both single and parallel boiling channel flow. With regard to the power limits the experimental results verified that the single boiling channel performance was intimately related to that of the parallel channels. In the latter case the additional inter-channel factors with attenuating effects were studied. Some optimum values of the parameters were observed.

  2. Physiology Of Prolonged Bed Rest

    Science.gov (United States)

    Greenleaf, John E.

    1991-01-01

    Report describes physiological effects of prolonged bed rest. Rest for periods of 24 hours or longer deconditions body to some extent; healing proceeds simultaneously with deconditioning. Report provides details on shifts in fluid electrolytes and loss of lean body mass, which comprises everything in body besides fat - that is, water, muscle, and bone. Based on published research.

  3. How to Find Bed Bugs

    Science.gov (United States)

    Find and correctly identify an infestation early before it becomes widespread. Look for rusty or reddish stains and pinpoint dark spots on bed sheets or mattresses, and search for bugs near the piping, seams and tags of the mattress and box spring.

  4. Numerical simulation of gas-solid flow in an interconnected fluidized bed

    Directory of Open Access Journals (Sweden)

    Canneto Giuseppe

    2015-01-01

    Full Text Available The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed.

  5. Advanced sorbent development progam; development of sorbents for moving-bed and fluidized-bed applications

    International Nuclear Information System (INIS)

    Ayala, R.E.; Venkataramani, V.S.

    1998-01-01

    The integrated gasification combined cycle (IGCC) power system using high-temperature coal gas cleanup is one of the most promising advanced technologies for the production of electric power from coal in an environmentally acceptable manner. Unlike conventional low-temperature cleanup systems that require costly heat exchangers, high-temperature coal gas cleanup systems can be operated near 482-538 C (900-1000F) or higher, conditions that are a closer match with the gasifier and turbine components in the IGCC system, thus resulting is a more efficient overall system. GE is developing a moving-bed, high-temperature desulfurization system for the IGCC power cycle in which zinc-based regenerable sorbents are currently being used as desulfurization sorbents. Zinc titanate and other proprietary zinc-based oxides are being considered as sorbents for use in the Clean Coal Technology Demonstration Program at Tampa Electric Co.s (TECo) Polk Power Station. Under cold startup conditions at TECo, desulfurization and regeneration may be carried out at temperatures as low as 343 C (650 F), hence a versatile sorbent is desirable to perform over this wide temperature range. A key to success in the development of high-temperature desulfurization systems is the matching of sorbent properties for the selected process operating conditions, namely, sustainable desulfurization kinetics, high sulfur capacity, and mechanical durability over multiple cycles. Additionally, the sulfur species produced during regeneration of the sorbent must be in a form compatible with sulfur recovery systems, such as sulfuric acid or elemental sulfur processes. The overall objective of this program is to develop regenerable sorbents for hydrogen sulfide removal from coal-derived fuel gases in the temperature range 343-538 C (650-1000 F). Two categories of reactor configurations are being considered: moving-bed reactors and fluidized-bed (bubbling and circulating) reactors. In addition, a cost assessment and

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

    Directory of Open Access Journals (Sweden)

    Kakaras Emmanuel

    2003-01-01

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

  7. The NASA Bed Rest Project

    Science.gov (United States)

    Rhodes, Bradley; Meck, Janice

    2005-01-01

    NASA s National Vision for Space Exploration includes human travel beyond low earth orbit and the ultimate safe return of the crews. Crucial to fulfilling the vision is the successful and timely development of countermeasures for the adverse physiological effects on human systems caused by long term exposure to the microgravity environment. Limited access to in-flight resources for the foreseeable future increases NASA s reliance on ground-based analogs to simulate these effects of microgravity. The primary analog for human based research will be head-down bed rest. By this approach NASA will be able to evaluate countermeasures in large sample sizes, perform preliminary evaluations of proposed in-flight protocols and assess the utility of individual or combined strategies before flight resources are requested. In response to this critical need, NASA has created the Bed Rest Project at the Johnson Space Center. The Project establishes the infrastructure and processes to provide a long term capability for standardized domestic bed rest studies and countermeasure development. The Bed Rest Project design takes a comprehensive, interdisciplinary, integrated approach that reduces the resource overhead of one investigator for one campaign. In addition to integrating studies operationally relevant for exploration, the Project addresses other new Vision objectives, namely: 1) interagency cooperation with the NIH allows for Clinical Research Center (CRC) facility sharing to the benefit of both agencies, 2) collaboration with our International Partners expands countermeasure development opportunities for foreign and domestic investigators as well as promotes consistency in approach and results, 3) to the greatest degree possible, the Project also advances research by clinicians and academia alike to encourage return to earth benefits. This paper will describe the Project s top level goals, organization and relationship to other Exploration Vision Projects, implementation

  8. Adult Bed-Wetting: A Concern?

    Science.gov (United States)

    Adult bed-wetting: A concern? My 24-year-old husband has started to wet the bed at ... of Privacy Practices Notice of Nondiscrimination Manage Cookies Advertising Mayo Clinic is a not-for-profit organization ...

  9. Find a Bed Bug Pesticide Product

    Science.gov (United States)

    Introduces the Bed Bug Product Search Tool, to help consumers find EPA-registered pesticides for bed bug infestation control. Inclusion in this database is not an endorsement. Always follow label directions carefully.

  10. EPA-Registered Bed Bug Products

    Science.gov (United States)

    ... rest or hide in hampers, bed frames, even furniture); Failing to treat adjacent areas where bed bugs ... to work (some pesticides, such as desiccators or growth regulators, may be very effective but take some ...

  11. Bed Bug Guidance for School Nurses

    Science.gov (United States)

    School nurses are often called upon to provide vital information to students, parents, teachers, and administrators. These tips on identifying, managing and preventing bed bugs will help you to effectively respond if bed bugs appear in your school.

  12. Bacillus cereus in free-stall bedding.

    Science.gov (United States)

    Magnusson, M; Svensson, B; Kolstrup, C; Christiansson, A

    2007-12-01

    To increase the understanding of how different factors affect the bacterial growth in deep sawdust beds for dairy cattle, the microbiological status of Bacillus cereus and coliforms in deep sawdust-bedded free stalls was investigated over two 14-d periods on one farm. High counts of B. cereus and coliforms were found in the entire beds. On average, 4.1 log(10) B. cereus spores, 5.5 log(10) B. cereus, and 6.7 log(10) coliforms per gram of bedding could be found in the upper layers of the sawdust likely to be in contact with the cows' udders. The highest counts of B. cereus spores, B. cereus, and coliforms were found in the bedding before fresh bedding was added, and the lowest immediately afterwards. Different factors of importance for the growth of B. cereus in the bedding material were explored in laboratory tests. These were found to be the type of bedding, pH, and the type and availability of nutrients. Alternative bedding material such as peat and mixtures of peat and sawdust inhibited the bacterial growth of B. cereus. The extent of growth of B. cereus in the sawdust was increased in a dose-dependent manner by the availability of feces. Urine added to different bedding material raised the pH and also led to bacterial growth of B. cereus in the peat. In sawdust, a dry matter content greater than 70% was needed to lower the water activity to 0.95, which is needed to inhibit the growth of B. cereus. In an attempt to reduce the bacterial growth of B. cereus and coliforms in deep sawdust beds on the farm, the effect of giving bedding daily or a full replacement of the beds was studied. The spore count of B. cereus in the back part of the free stalls before fresh bedding was added was 0.9 log units lower in stalls given daily bedding than in stalls given bedding twice weekly. No effect on coliform counts was found. Replacement of the entire sawdust bedding had an effect for a short period, but by 1 to 2 mo after replacement, the counts of B. cereus spores in the

  13. Experimental investigation of a draft tube spouted bed for effects of geometric parameters on operation

    DEFF Research Database (Denmark)

    Azizaddini, Seyednezamaddin; Lin, Weigang; Dam-Johansen, Kim

    2016-01-01

    Experiments are performed in a draft tube spouted bed (DTSB) to investigate effects of the operating conditions and the geometric parameters on the hydrodynamics. Geometry parameters, such as heights of the entrained zone, draft tube inner diameter, inner angle of the conical section were studied....... Increasing the draft tube inner diameter, sharper inner angle of the conical section and higher height of entrained zone increase the internal solid circulation rate and the pressure drop. Even though, for all different configurations, higher gas feeding rate leads to higher internal solid circulation rate...

  14. Seasonal overturning circulation in the Red Sea: 2. Winter circulation

    Science.gov (United States)

    Yao, Fengchao; Hoteit, Ibrahim; Pratt, Larry J.; Bower, Amy S.; Köhl, Armin; Gopalakrishnan, Ganesh; Rivas, David

    2014-04-01

    The shallow winter overturning circulation in the Red Sea is studied using a 50 year high-resolution MITgcm (MIT general circulation model) simulation with realistic atmospheric forcing. The overturning circulation for a typical year, represented by 1980, and the climatological mean are analyzed using model output to delineate the three-dimensional structure and to investigate the underlying dynamical mechanisms. The horizontal model circulation in the winter of 1980 is dominated by energetic eddies. The climatological model mean results suggest that the surface inflow intensifies in a western boundary current in the southern Red Sea that switches to an eastern boundary current north of 24°N. The overturning is accomplished through a cyclonic recirculation and a cross-basin overturning circulation in the northern Red Sea, with major sinking occurring along a narrow band of width about 20 km along the eastern boundary and weaker upwelling along the western boundary. The northward pressure gradient force, strong vertical mixing, and horizontal mixing near the boundary are the essential dynamical components in the model's winter overturning circulation. The simulated water exchange is not hydraulically controlled in the Strait of Bab el Mandeb; instead, the exchange is limited by bottom and lateral boundary friction and, to a lesser extent, by interfacial friction due to the vertical viscosity at the interface between the inflow and the outflow.

  15. Modelling tidal current-induced bed shear stress and palaeocirculation in an epicontinental seaway: the Bohemian Cretaceous Basin, Central Europe

    Czech Academy of Sciences Publication Activity Database

    Mitchell, A. J.; Uličný, David; Hampson, G. J.; Allison, P. A.; Gorman, G. J.; Piggott, M. D.; Wells, M. R.; Pain, C. C.

    2010-01-01

    Roč. 57, č. 2 (2010), s. 359-388 ISSN 0037-0746 R&D Projects: GA AV ČR(CZ) IAA300120609 Institutional research plan: CEZ:AV0Z30120515 Keywords : bed shear stress * Bohemian Cretaceous Basin * epicontinental sea * tidal circulation * Turonian Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.229, year: 2010

  16. Fluidization quality analyzer for fluidized beds

    Science.gov (United States)

    Daw, C.S.; Hawk, J.A.

    1995-07-25

    A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.

  17. Fluidized bed dry dense medium coal beneficiation

    CSIR Research Space (South Africa)

    North, Brian C

    2017-10-01

    Full Text Available medium beneficiation using a fluidized bed was investigated. Bed materials of sand, magnetite and ilmenite were used in a laboratory sized cylindrical fluidized bed. The materials were individually tested, as were mixes of sand and heavy minerals. Coal...

  18. Review of acute cancer beds.

    LENUS (Irish Health Repository)

    Evans, D S

    2012-01-01

    A review of admissions to cancer services at University Hospital Galway (UHG) was undertaken to assess the appropriateness of hospital usage. All cancer specialty patients admitted from 26-28 May 2009 were reviewed (n = 82). Chi square tests, Exact tests, and One-way ANOVA were utilised to analyse key issues emerging from the data. Fifty (61%) were classified as emergencies. Twenty three (67%) occupied a designated cancer bed with 24 (30%) in outlying non-oncology wards. The mean length of stay was 29.3 days. Possible alternatives to admission were identified for 15 (19%) patients. There was no evidence of discharge planning for 50 (60%) admissions. There is considerable potential to make more appropriate utilisation of UHG for cancer patients, particularly in terms of reducing bed days and length of stay and the proportion of emergency cancer admissions, and further developing integrated systems of discharge planning.

  19. Designing a CR Test bed

    DEFF Research Database (Denmark)

    Cattoni, Andrea Fabio; Buthler, Jakob Lindbjerg; Tonelli, Oscar

    2014-01-01

    with their own set up, since the potential costs and efforts could not pay back in term of expected research results. Software Defined Radio solutions offer an easy way to communication researchers for the development of customized research test beds. While several hardware products are commercially available......, an overview on common research-oriented software products for SDR development, namely GNU Radio, Iris, and ASGARD, will be provided, including how to practically start the software development of simple applications. Finally, best practices and examples of all the software platforms will be provided, giving...... they are up and running in generating results. With this chapter we would like to provide a tutorial guide, based on direct experience, on how to enter in the world of test bed-based research, providing both insight on the issues encountered in every day development, and practical solutions. Finally...

  20. THE BAUXITES AND JELAR - BEDS

    Directory of Open Access Journals (Sweden)

    Krešimir Sakač

    1993-12-01

    Full Text Available Minor bauxite deposits and occurrences were formed in technically disturbed environments in the middle part of the Adriatic geotectonic unit in Dinarides, contemporary with the clastic Jelar-beds in the Late Lutetian time. Uneven chemical composition of these Eocene bauxites, their sporadic occurrences in developed paleorelief as well as characteristic petrographic composition of the immediate overlying rocks point out at different genetical conditions (the paper is published in Croatian.

  1. The Low temperature CFB gasifier

    DEFF Research Database (Denmark)

    Stoholm, P.; Nielsen, Rasmus Glar; Fock, Martin W.

    2003-01-01

    %) particle separation by the hot secondary cyclone. The next LT-CFB experiment, currently under preparation, is expected to be on either municipal/industrial waste or animal manure. Eventually a 500 kW LT-CFB test plant scheduled for commission during summer 2003, and the anticipated primary LT......The Low Temperature Circulating Fluidised Bed (LT-CFB) gasification process aims at avoiding problems due to ash deposition and agglomeration when using difficult fuels such as agricultural biomass and many waste materials. This, as well as very simple gas cleaning, is achieved by pyrolysing...... the fuel at around 650?C in a CFB reaction chamber and subsequently gasifying the char at around 730oC in a slowly fluidised bubbling bed chamber located in the CFB particle recirculation path. In this paper the novel LT-CFB concept is further described together with the latest test results from the 50 k...

  2. Plasma assisted measurements of alkali metal concentrations in pressurised combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R; Haeyrinen, V [Tampere Univ. of Technology (Finland)

    1997-10-01

    In this project the continuous alkali measurement method plasma excited alkali resonance line spectroscopy (PEARLS) was developed, tested and demonstrated in pressurised combustion facilities. The PEARLS method has been developed at Tampere University of Technology (TUT). During 1994-1996 the PEARLS method was developed from the laboratory level to an industrial prototype. The alkali measuring instrument has been tested and used for regular measurements in four different pressurised combustion installations ranging up to industrial pilot scale. The installations are: (1) a pressurised entrained flow reactor (PEFR) at VTT Energy in Jyvaeskylae, Finland (2) a pressurised fluidised bed combustion facility, called FRED, at DMT in Essen, Germany. (3) a 10 MW pressurised circulating fluidised bed combustion pilot plant at Foster Wheeler Energia Oy in Karhula, Finland (4) PFBC Research Facility at ABB Carbon in Finspaang, Sweden

  3. Advances in fluidized bed technologies

    International Nuclear Information System (INIS)

    Mutanen, K.

    1992-01-01

    Atmospheric fluidized bed combustion (AFBC) has advanced into industrial cogeneration and utility-scale electric generation. During the 1980's AFBC became the dominant technology in the United States for power generation systems fired with solid fuels. Development of pressurized fluidized bed combustion/gasification (PFB/G) has grown rapidly from small bench-scale rigs to large pilot and demonstration plants. AFBC as large as 160 MWe in capacity are now in operation, while pressurized combustion systems generating 80 MWe have started up two years ago. The major driving forces behind development of fluidized bed technologies are all the time strictening emission control regulations, need for fuel flexibility, repowering of older power plants and need for higher efficiency in electricity generation. Independent power producers (IPP) and cogenerators were the first ones in the United States who accepted AFBC for wide commercial use. Their role will be dominant in the markets of the 1990's also. Developers of AFBC systems are working on designs that reduce investment costs, decrease emissions and offer even higher reliability and availability in utility-scale applications while developers of PFBC/G work on designs that increase plant efficiencies, allow modular construction, decrease emissions further and reduce the cost of generating power. This paper presents technological background, commercial status, boiler performance, emissions and future developments for both AFBC and PFBC/G systems

  4. 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

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

    International Nuclear Information System (INIS)

    Chaivatamaset, Pawin; Tia, Suvit

    2015-01-01

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

  6. Method and apparatus for a combination moving bed thermal treatment reactor and moving bed filter

    Energy Technology Data Exchange (ETDEWEB)

    Badger, Phillip C.; Dunn, Jr., Kenneth J.

    2015-09-01

    A moving bed gasification/thermal treatment reactor includes a geometry in which moving bed reactor particles serve as both a moving bed filter and a heat carrier to provide thermal energy for thermal treatment reactions, such that the moving bed filter and the heat carrier are one and the same to remove solid particulates or droplets generated by thermal treatment processes or injected into the moving bed filter from other sources.

  7. Clinical evaluation of an automated turning bed.

    Science.gov (United States)

    Melland, H I; Langemo, D; Hanson, D; Olson, B; Hunter, S

    1999-01-01

    The purposes of this study were to assess client comfort and sleep quality, client physiologic response (skin and respiratory status), the effect on the need for caregiver assistance, and cost when using an automated turning bed. Nonexperimental, evaluative study. Twenty-four adult home or long-term care resident subjects who had a degenerative disease, spinal cord injury, stroke, cerebral palsy, or back surgery. Each subject agreed to use the automated turning bed for four weeks. Researchers completed a demographic survey and skin assessment, and assessed each subject for pressure ulcer risk and for the need of assistance of a care giver for turning before and after the four weeks of using the turning bed. Subjects rated the turning bed in terms of comfort and sleep quality. Subjects rated the turning bed as more comfortable than their own bed and expressed satisfaction at the pain relief attained when on the turning bed. While using the turning bed, there was a significant improvement in sleep quality. No skin breakdown or deterioration in respiratory status occurred. Fewer subjects required the assistance of a caregiver for turning when on the turning bed. This automated turning bed shows great promise in meeting a need for patients with limited mobility whether they are homebound or in a residential community. Future studies that further investigate use of the turning bed for postoperative back patients while still in the acute care setting are indicated. Replicative studies with a larger sample size are also indicated.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-31

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

  9. Executive function on the 16-day of bed rest in young healthy men

    Science.gov (United States)

    Ishizaki, Yuko; Fukuoka, Hideoki; Tanaka, Hidetaka; Ishizaki, Tatsuro; Fujii, Yuri; Hattori-Uchida, Yuko; Nakamura, Minako; Ohkawa, Kaoru; Kobayashi, Hodaka; Taniuchi, Shoichiro; Kaneko, Kazunari

    2009-05-01

    Microgravity due to prolonged bed rest may cause changes in cerebral circulation, which is related to brain function. We evaluate the effect of simulated microgravity due to a 6° head-down tilt bed rest experiment on executive function among 12 healthy young men. Four kinds of psychoneurological tests—the table tapping test, the trail making test, the pointing test and losing at rock-paper-scissors—were performed on the baseline and on day 16 of the experiment. There was no significant difference in the results between the baseline and day 16 on all tests, which indicated that executive function was not impaired by the 16-day 6° head-down tilting bed rest. However, we cannot conclude that microgravity did not affect executive function because of the possible contribution of the following factors: (1) the timing of tests, (2) the learning effect, or (3) changes in psychophysiology that were too small to affect higher brain function.

  10. The influence of sediment transport rate on the development of structure in gravel bed rivers

    Science.gov (United States)

    Ockelford, Annie; Rice, Steve; Powell, Mark; Reid, Ian; Nguyen, Thao; Tate, Nick; Wood, Jo

    2013-04-01

    Although adjustments of surface grain size are known to be strongly influenced by sediment transport rate little work has systematically explored how different transport rates can affect the development of surface structure in gravel bed rivers. Specifically, it has been well established that the transport of mixed sized sediments leads to the development of a coarser surface or armour layer which occurs over larger areas of the gravel bed. Armour layer development is known to moderate overall sediment transport rate as well as being extremely sensitive to changes in applied shear stress. However, during this armouring process a bed is created where, smaller gain scale changes, to the bed surface are also apparent such as the development of pebble clusters and imbricate structures. Although these smaller scale changes affect the overall surface grain size distribution very little their presence has the ability to significantly increase the surface stability and hence alter overall sediment transport rates. Consequently, the interplay between the moderation of transport rate as a function of surface coarsening at a larger scale and moderation of transport rate as a function of the development of structure on the bed surface at the smaller scale is complicated and warrants further investigation. During experiments a unimodal grain size distribution (σg = 1.30, D50 = 8.8mm) was exposed to 3 different levels of constant discharge that produced sediment transport conditions ranging from marginal transport to conditions approaching full mobility of all size fractions. Sediment was re-circulated during the experiments surface grain size distribution bed load and fractional transport rates were measured at a high temporal resolution such that the time evolution of the beds could be fully described. Discussion concentrates on analysing the effects of the evolving bed condition sediment transport rate (capacity) and transported grain size (competence). The outcome of this

  11. Secondary circulation in river junctions even at very low flow momentum ratios : The legacy effects of point bar formation

    NARCIS (Netherlands)

    Moradi, Gelare; Rennie, Colin; Vermeulen, Bart; Cardot, Romain; Lane, Stuart

    2018-01-01

    River confluences remain a challenging subject because of their 3D geometry which leads to a complex, three-dimensional mean and turbulent velocity processes. Since secondary circulation plays an important role in flow hydrodynamics and the development of bank erosion, bed scour and bar formation,

  12. Energetic, ecologic and fluid-dynamic analysis of a fluidized bed gasifier operating with sugar cane bagasse

    International Nuclear Information System (INIS)

    Diniz Filho, Paulo Tasso; Silveira, Jose Luz; Tuna, Celso Eduardo; Lamas, Wendell de Queiroz

    2013-01-01

    This work aims to study the thermodynamic, ecological and fluid-dynamic aspects of a circulating fluidized bed gasifier using sugar cane bagasse as biomass, in order to estimate a model of its normal operation. In the initial stage was analysed the composition of biomass selected (sugar cane bagasse) and its lower heating value (LHV) was calculated. The energy balance of the gasifier was done, being the volumetric flow of air, synthesis gas and biomass estimated. Also the power produced by this gasifier was theoretically estimated. Then the circulating fluidized bed gasifier was designed for operation with approximately 100 kg/h of processed biomass. Cross-sectional area of the reactor, feeder size, diameter of the exit zone of the gases and minimum height of the expanded bed were selected. Some bed gasifier hydrodynamic factors were also studied. The minimum fluidization velocity, fluidization terminal velocity, and average fluidizing velocity were calculated, in order to understand the fluid-dynamic behaviour of gasification of this fuel. It was obtained a theoretical model that can support a possible prototype of circulating fluidized bed gasifier biomass. Finally, there were studied the ecological aspects of the gasifier, through an overall methodology. Ecological efficiencies were estimated for two scenarios: first considering the carbon cycle and thereafter disregarding the carbon cycle. In both cases, it can be proved the ecological viability of the project. -- Highlights: • we develop a methodology to size a fluidized bed gasifier. • we validate this methodology comparing to a fixed bed gasifier values. • we aggregate ecological efficiency to this methodology

  13. Seasonal overturning circulation in the Red Sea: 2. Winter circulation

    KAUST Repository

    Yao, Fengchao

    2014-04-01

    The shallow winter overturning circulation in the Red Sea is studied using a 50 year high-resolution MITgcm (MIT general circulation model) simulation with realistic atmospheric forcing. The overturning circulation for a typical year, represented by 1980, and the climatological mean are analyzed using model output to delineate the three-dimensional structure and to investigate the underlying dynamical mechanisms. The horizontal model circulation in the winter of 1980 is dominated by energetic eddies. The climatological model mean results suggest that the surface inflow intensifies in a western boundary current in the southern Red Sea that switches to an eastern boundary current north of 24N. The overturning is accomplished through a cyclonic recirculation and a cross-basin overturning circulation in the northern Red Sea, with major sinking occurring along a narrow band of width about 20 km along the eastern boundary and weaker upwelling along the western boundary. The northward pressure gradient force, strong vertical mixing, and horizontal mixing near the boundary are the essential dynamical components in the model\\'s winter overturning circulation. The simulated water exchange is not hydraulically controlled in the Strait of Bab el Mandeb; instead, the exchange is limited by bottom and lateral boundary friction and, to a lesser extent, by interfacial friction due to the vertical viscosity at the interface between the inflow and the outflow. Key Points Sinking occurs in a narrow boundary layer along the eastern boundary Surface western boundary current switches into an eastern boundary current Water exchange in the Strait of Bab el Mandeb is not hydraulically controlled © 2014. American Geophysical Union. All Rights Reserved.

  14. The Safety of Hospital Beds: Ingress, Egress, and In-Bed Mobility.

    Science.gov (United States)

    Morse, Janice M; Gervais, Pierre; Pooler, Charlotte; Merryweather, Andrew; Doig, Alexa K; Bloswick, Donald

    2015-01-01

    To explore the safety of the standard and the low hospital bed, we report on a microanalysis of 15 patients' ability to ingress, move about the bed, and egress. The 15 participants were purposefully selected with various disabilities. Bed conditions were randomized with side rails up or down and one low bed with side rails down. We explored the patients' use of the side rails, bed height, ability to lift their legs onto the mattress, and ability to turn, egress, and walk back to the chair. The standard bed was too high for some participants, both for ingress and egress. Side rails were used by most participants when entering, turning in bed, and exiting. We recommend that side rails be reconsidered as a means to facilitate in-bed movement, ingress, and egress. Furthermore, single deck height settings for all patients are not optimal. Low beds as a safety measure must be re-evaluated.

  15. Conceptual design of an active magnetic regenerative heat circulator based on self-heat recuperation technology

    International Nuclear Information System (INIS)

    Kotani, Yui; Kansha, Yasuki; Tsutsumi, Atsushi

    2013-01-01

    A conceptual design of an active magnetic regenerative (AMR) heat circulator for self-heat recuperation to realize energy savings in thermal processes is proposed. The process fluid heat is recuperated by the magnetocaloric effect of ferromagnetic material through the AMR heat circulation cycle. In an AMR heat circulator, all the process fluid heat is circulated and no make-up heat is added to raise the process fluid to its set temperature. A one-dimensional mathematical model of the AMR heat circulator was constructed to understand its behavior and verify its energy-saving potential. From the constructed one-dimensional mathematical model, it is seen that AMR heat circulator has potential to drastically reduce the total energy consumption in a thermal process. The temperature–entropy diagram shows that in order to gain the maximum energy saving, optimization of the parameters such as the flow rate and geometry of the ferromagnetic working material beds is needed. - Highlights: • Self-heat recuperative active magnetic regenerative heat circulator is introduced. • One-dimensional model is constructed to verify its energy-saving potential. • Total energy consumption in thermal process is drastically reduced. • Further energy can be saved by reducing the overlapping of thermodynamic cycles

  16. The Invertibility, Explicit Determinants, and Inverses of Circulant and Left Circulant and g-Circulant Matrices Involving Any Continuous Fibonacci and Lucas Numbers

    Directory of Open Access Journals (Sweden)

    Zhaolin Jiang

    2014-01-01

    Full Text Available Circulant matrices play an important role in solving delay differential equations. In this paper, circulant type matrices including the circulant and left circulant and g-circulant matrices with any continuous Fibonacci and Lucas numbers are considered. Firstly, the invertibility of the circulant matrix is discussed and the explicit determinant and the inverse matrices by constructing the transformation matrices are presented. Furthermore, the invertibility of the left circulant and g-circulant matrices is also studied. We obtain the explicit determinants and the inverse matrices of the left circulant and g-circulant matrices by utilizing the relationship between left circulant, g-circulant matrices and circulant matrix, respectively.

  17. [Special beds. Pulmonary therapy system].

    Science.gov (United States)

    Calixto Rodríguez, Joaquín; Rodríguez Martínez, Xavier; Marín i Vivó, Gemma; Paunellas Albert, Josep

    2008-10-01

    To be bedridden reduces one's capacity to move and produces muscular debility that affects the respiratory system leading to a decreased effectiveness in expectoration, the ability to spit up sputum. The pulmonary therapy system integrated in a bed is the result of applying motorized elements to the articulation points of the bad in order to achieve safe positions at therapeutic angles, which improve the breathing-perfusion (blood flow) relationship. This system also makes it possible to apply vibration waves to the patient which favor the elimination of bronchial-pulmonary secretions, the rehabilitation of the bedridden patient and decrease the work load for nursing personnel.

  18. Particle bed reactor scaling relationships

    Science.gov (United States)

    Slovik, G.; Araj, K.; Horn, F. L.; Ludewig, H.; Benenati, R.

    The Particle Bed Reactor (PBR) concept can be used in several applications both as part of a power generating system or as a direct propulsion unit. In order to carry out optimization studies of systems involving a PBR, it is necessary to know the variation of the critical mass with pertinent system parameters such as weight, size, power level and thrust level. A parametric study is presented for all the practical combinations of fuel and moderating material. The PBR is described, the practical combinations of materials and dimensions are discussed, and an example is presented.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-03-15

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

  20. Conversion of ammonium uranyl carbonate to UO2 in a fluidized bed

    International Nuclear Information System (INIS)

    Zhao Jun; Qiu Lufu; Zhong Xing; Xu Heqing

    1989-11-01

    The conversion of AUC (Ammonium Uranyl Carbonate) to UO 2 was studied in a fluidized bed of 60 mm inner diameter based on the thermodynamics and kinetics data of decomposition-reduction of AUC. The influence of the reaction temperature, composition of fluidization gas and fluidization velocity on conversion were investigated by using N 2 , Ar and circulation gas (mixing gas of H 2 and CO obtained from the exhaust gas of the decomposition of AUC by catalyst crack-conversion) as the fluidization gas. The throughput is up to the high levels (3.32 kg(wet)/h·L) by using circulation gas or mixing of circulation gas and Ar (< 21%) as the fluidization gas when the reaction temperature exceeds 570 deg C

  1. Proper Sizing of Circulation Pumps

    DEFF Research Database (Denmark)

    Tommerup, Henrik M.; Nørgaard, Jørgen

    2007-01-01

    The paper describes the preliminary results from field tests of replacing various types of old pumps used for circulating water in heating systems in single- and double-family houses with new types of pumps. The tests were carried out in Denmark for the Danish Electricity Savings Trust, but the r......The paper describes the preliminary results from field tests of replacing various types of old pumps used for circulating water in heating systems in single- and double-family houses with new types of pumps. The tests were carried out in Denmark for the Danish Electricity Savings Trust...

  2. Fluid-bed process for SYNROC production

    International Nuclear Information System (INIS)

    Ackerman, F.J.; Grens, J.Z.; Ryerson, F.J.; Hoenig, C.L.; Bazan, F.; Peters, P.E.; Smith, R.; Campbell, J.H.

    1983-01-01

    SYNROC is a titanate-based ceramic waste developed for the immobilization of high-level nuclear reactor waste. Lawrence Livermore National Laboratory (LLNL) has investigated a fluid-bed technique for the large-scale production of SYNROC precursor powders. Making SYNROC in a fluid bed permits slurry drying, calcination and reduction-oxidation reactions to be carried out in a single unit. We present the results of SYNROC fluid-bed studies from two fluid-bed units 10 cm in diameter: an internally heated fluid-bed unit developed by Exxon Idaho and an externally heated unit constructed at LLNL. Bed operation over a range of temperatures, feed rates, fluidizing rates, and redox conditions indicate that SYNROC powders of a high density and a uniform particle size can be produced. These powders facilitate the densification step and yield dense ceramics (greater than 95% theoretical density) with well-developed phases and low leaching rates

  3. On partial fluidization in rotating fluidized beds

    International Nuclear Information System (INIS)

    Kao, J.; Pfeffer, R.; Tardos, G.I.

    1987-01-01

    In a rotating fluidized bed, unlike in a conventional fluidized bed, the granules are fluidized layer by layer from the (inner) free surface outward at increasing radius as the gas velocity is increased. This is a very significant and interesting phenomenon and is extremely important in the design of these fluidized beds. The phenomenon was first suggested in a theoretical analysis and recently verified experimentally in the authors' laboratory. However, in the first paper, the equations presented are too cumbersome and the influence of bed thickness is not clearly stated. In this note the authors present simplified equations, based on that paper, for the pressure drop and the minimum fluidizing velocities in a rotating fluidized bed. Experimental data are also shown and compared with the theoretical model, and the effect of bed thickness is shown. Furthermore, an explanation for the observation of a maximum in the pressure drop vs. velocity curve instead of the plateau derived by Chen is proposed

  4. MIT pebble bed reactor project

    Energy Technology Data Exchange (ETDEWEB)

    Kadak, Andrew C. [Massachusetts Institute of Technology, Cambridge (United States)

    2007-03-15

    The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis.

  5. MIT pebble bed reactor project

    International Nuclear Information System (INIS)

    Kadak, Andrew C.

    2007-01-01

    The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis

  6. SPOUTED BED DESIGN CONSIDERATIONS FOR COATED NUCLEAR FUEL PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Douglas W.

    2017-07-01

    High Temperature Gas Cooled Reactors (HTGRs) are fueled with tristructural isotropic (TRISO) coated nuclear fuel particles embedded in a carbon-graphite fuel body. TRISO coatings consist of four layers of pyrolytic carbon and silicon carbide that are deposited on uranium ceramic fuel kernels (350µm – 500µm diameters) in a concatenated series of batch depositions. Each layer has dedicated functions such that the finished fuel particle has its own integral containment to minimize and control the release of fission products into the fuel body and reactor core. The TRISO coatings are the primary containment structure in the HTGR reactor and must have very high uniformity and integrity. To ensure high quality TRISO coatings, the four layers are deposited by chemical vapor deposition (CVD) using high purity precursors and are applied in a concatenated succession of batch operations before the finished product is unloaded from the coating furnace. These depositions take place at temperatures ranging from 1230°C to 1550°C and use three different gas compositions, while the fuel particle diameters double, their density drops from 11.1 g/cm3 to 3.0 g/cm3, and the bed volume increases more than 8-fold. All this is accomplished without the aid of sight ports or internal instrumentation that could cause chemical contamination within the layers or mechanical damage to thin layers in the early stages of each layer deposition. The converging section of the furnace retort was specifically designed to prevent bed stagnation that would lead to unacceptably high defect fractions and facilitate bed circulation to avoid large variability in coating layer dimensions and properties. The gas injection nozzle was designed to protect precursor gases from becoming overheated prior to injection, to induce bed spouting and preclude bed stagnation in the bottom of the retort. Furthermore, the retort and injection nozzle designs minimize buildup of pyrocarbon and silicon carbide on the

  7. The effect of self-leveling on debris bed coolability under severe accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Basso, S.; Konovalenko, A. [Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Roslagstullsbacken 21, D5, Stockholm 106 91 (Sweden); Yakush, S.E. [Institute for Problems in Mechanics of the Russian Academy of Sciences, Ave. Vernadskogo 101 Bldg 1, Moscow 119526 (Russian Federation); Kudinov, P. [Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Roslagstullsbacken 21, D5, Stockholm 106 91 (Sweden)

    2016-08-15

    Highlights: • A model for coolability of a self-leveling, variable-shape debris bed is proposed. • Sensitivity analysis is performed to screen out the less influential input parameters. • A small fraction of scenarios has initially a non-coolable debris bed configuration. • The fraction of non-coolable scenarios decreases with time due to self-leveling. - Abstract: Nordic-type boiling water reactors employ melt fragmentation, quenching, and long term cooling of the debris bed in a deep pool of water under the reactor vessel as a severe accident (SA) mitigation strategy. The height and shape of the bed are among the most important factors that determine if decay heat can be removed from the porous debris bed by natural circulation of water. The debris bed geometry depends on its formation process (melt release, fragmentation, sedimentation and settlement on the containment basemat), but it also changes with time afterwards, due to particle redistribution promoted by coolant flow (self-leveling). The ultimate goal of this work is to develop an approach to the assessment of the probability that debris in such a variable-shape bed can reach re-melting (which means failure of SA mitigation strategy), i.e. the time necessary for the slumping debris bed to reach a coolable configuration is larger than the time necessary for the debris to reach the re-melting temperature. For this purpose, previously developed models for particulate debris spreading by self-leveling and debris bed dryout are combined to assess the time necessary to reach a coolable state and evaluate its uncertainty. Sensitivity analysis was performed to screen out less important input parameters, after which Monte Carlo simulation was carried out in order to collect statistical characteristics of the coolability time. The obtained results suggest that, given the parameters ranges typical of Nordic BWRs, only a small fraction of debris beds configurations exhibits the occurrence of dryout. Of the

  8. Gas distributor for fluidized bed coal gasifier

    Science.gov (United States)

    Worley, Arthur C.; Zboray, James A.

    1980-01-01

    A gas distributor for distributing high temperature reaction gases to a fluidized bed of coal particles in a coal gasification process. The distributor includes a pipe with a refractory reinforced lining and a plurality of openings in the lining through which gas is fed into the bed. These feed openings have an expanding tapered shape in the downstream or exhaust direction which aids in reducing the velocity of the gas jets as they enter the bed.

  9. Circulating fluidized-bed technology - toward zero CO{sub 2} emissions

    Energy Technology Data Exchange (ETDEWEB)

    Timo Jaentti; Timo Eriksson; Arto Hotta; Timo Hyppaenen; Kalle Nuortimo [Foster Wheeler Energia Oy, Varkaus (Finland)

    2006-07-01

    This paper presents the existing status of CFB technology in respect of boiler efficiency and fuel flexibility. Examples of the high efficiency repowering CFB projects both with sub and supercritical steam parameters from Estonia (Narva) and Poland (Turow and Lagisza) are presented. The paper also describes experiences from one utility CFB project in Thailand (NPS) with high biofuel and coal cocombustion capability. The main advantages of the CFB technology for oxycombustion and a development plan for the Oxy CFB is presented. 11 refs., 11 figs., 3 tabs.

  10. A study of dilute to dense flow in a circulating fluidized bed

    DEFF Research Database (Denmark)

    Ibsen, Claus Hübbe; Solberg, Tron; Hjertager, Bjørn H.

    2001-01-01

    are based on a Multiphase Computational Fluid Dynamics code, where the conservation equations for the solid phases are based on the kinetic theory of granular flow. The experimental data is used to evaluate the multiphase CFD code with alternative gas-solid drag models, which showed an improved agreement...

  11. Clean utilization of high sulphur petroleum coke by circulating fluidized bed combustion (CFBC) in Romania

    International Nuclear Information System (INIS)

    Dragos, L.; Flueraru, C.; Girjoaba, M.

    1996-01-01

    The economic and environmental problems caused by inefficient utilization of residual high-sulphur petroleum coke resulted from oil cracking in Romania is discussed. A special research programme applying CFBC technology has been carried out in the Institute for Power Equipment, Bucharest. The results from both laboratory facilities and pilot plant are presented. The main operating conditions and parameters are pointed out. Data on quality and composition of petroleum coke, combustion efficiency, temperature range in different zones and flue gas composition at distinct operating loads are given. The results obtained will be used for innovative design of CFBC boilers based on petroleum coke. A project for implementing a CFBC boiler in one of the Romanian oil refineries is being developed. An analysis of technical and economic advantages of these boilers for energy generation is presented

  12. Simulation of gas and particle flow in a circulating fluidized bed; Kaasu- ja kiintoainevirtauksen simulointi kiertoleijukattilassa

    Energy Technology Data Exchange (ETDEWEB)

    Kallio, S. [Aabo Akademi, Turku (Finland). Inst. of Heat Engineering

    1996-12-01

    The aim of this work was to study the effects of different parameters on the flow behaviour in a CFB riser by means of empirical models based on measurement data and a computer code based on macroscopic equations for multiphase flow. The effects of primary air velocity and riser geometry have been observed in the results. Simulation of secondary air flow proved to be problematic with the software used. In the project, also analyses of measurement data from cold model experiments has been performed. Moreover, the possibilities to use commercial CFD codes for simulation of gas-solids flow were investigated. The code FLUENT seemed promising. (author)

  13. Co-circulation of Usutu virus and West Nile virus in a reed bed ecosystem

    Czech Academy of Sciences Publication Activity Database

    Rudolf, Ivo; Bakonyi, T.; Šebesta, Oldřich; Mendel, Jan; Peško, Juraj; Betášová, Lenka; Blažejová, Hana; Venclíková, Kristýna; Straková, Petra; Nowotny, N.; Hubálek, Zdeněk

    2015-01-01

    Roč. 8, č. 520 (2015), s. 520 ISSN 1756-3305 EU Projects: European Commission(XE) 261504 - EDENEXT Institutional support: RVO:68081766 Keywords : Culex modestus * Usutu virus * West Nile virus * Flavivirus * Arbovirus * Surveillance * Mosquitoes Subject RIV: EE - Microbiology, Virology Impact factor: 3.234, year: 2015

  14. Behavior of Alkali Metals and Ash in a Low-Temperature Circulating Fluidized Bed (LTCFB) Gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas; Jensen, Peter Arendt; Henriksen, Ulrik Birk

    2016-01-01

    W and a 6 MW LTCFBgasifier. Of the total fuel ash entering the system, the largest fraction (40−50%) was retained in the secondary cyclone bottoms,while a lower amount (8−10%) was released as dust in the exit gas. Most of the alkali and alkaline earth metals were retained inthe solid ash, along with Si...... by the particle size and the cut size ofthe primary and secondary cyclones. A model accounting for the ash collection by the plant cyclones was shown to predict theproduct gas ash particle release reasonably well....

  15. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge

    DEFF Research Database (Denmark)

    Thomsen, Tobias Pape; Hauggaard-Nielsen, Henrik; Gøbel, Benny

    2017-01-01

    to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottom ashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded that LT-CFB gasification and co-gasification is a highly effective way to purify...

  16. Fluidized Bed Reactor as Solid State Fermenter

    Directory of Open Access Journals (Sweden)

    Krishnaiah, K.

    2005-01-01

    Full Text Available Various reactors such as tray, packed bed, rotating drum can be used for solid-state fermentation. In this paper the possibility of fluidized bed reactor as solid-state fermenter is considered. The design parameters, which affect the performances are identified and discussed. This information, in general can be used in the design and the development of an efficient fluidized bed solid-state fermenter. However, the objective here is to develop fluidized bed solid-state fermenter for palm kernel cake conversion into enriched animal and poultry feed.

  17. Studies on air ingress for pebble bed reactors

    International Nuclear Information System (INIS)

    Moore, R.L.; Oh, C.H.; Merrill, B.J.; Petti, D.A.

    2002-01-01

    A loss-of-coolant accident (LOCA) has been considered a critical event for helium-cooled pebbled bed reactors. Following helium depressurization, it is anticipated that unless countermeasures are taken air will enter the core through the break and then by molecular diffusion and ultimately by natural convection leading to oxidation of the in-core graphite structure and graphite pebbles. Thus, without any mitigating features a LOCA will lead to an air ingress event. The INEEL is studying such an event with two well-respected light water reactor transient response codes: RELAP5/ATHENA and MELCOR. To study the degree of graphite oxidation occurring due to an air ingress event, a MELCOR model of a reference pebble bed design was constructed. A modified version of MELCOR developed at INEEL, which includes graphite oxidation capabilities, and molecular diffusion of air into helium was used for these calculations. Results show that the lower reflector graphite consumes all of the oxygen before reaching the core. The results also show a long time delay between the time that the depressurization phase of the accident is over and the time that natural circulation air through the core occurs. (author)

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  19. Near-Bed Turbulent Kinetic Energy Budget Under a Large-Scale Plunging Breaking Wave Over a Fixed Bar

    Science.gov (United States)

    van der Zanden, Joep; van der A, Dominic A.; Cáceres, Iván.; Hurther, David; McLelland, Stuart J.; Ribberink, Jan S.; O'Donoghue, Tom

    2018-02-01

    Hydrodynamics under regular plunging breaking waves over a fixed breaker bar were studied in a large-scale wave flume. A previous paper reported on the outer flow hydrodynamics; the present paper focuses on the turbulence dynamics near the bed (up to 0.10 m from the bed). Velocities were measured with high spatial and temporal resolution using a two component laser Doppler anemometer. The results show that even at close distance from the bed (1 mm), the turbulent kinetic energy (TKE) increases by a factor five between the shoaling, and breaking regions because of invasion of wave breaking turbulence. The sign and phase behavior of the time-dependent Reynolds shear stresses at elevations up to approximately 0.02 m from the bed (roughly twice the elevation of the boundary layer overshoot) are mainly controlled by local bed-shear-generated turbulence, but at higher elevations Reynolds stresses are controlled by wave breaking turbulence. The measurements are subsequently analyzed to investigate the TKE budget at wave-averaged and intrawave time scales. Horizontal and vertical turbulence advection, production, and dissipation are the major terms. A two-dimensional wave-averaged circulation drives advection of wave breaking turbulence through the near-bed layer, resulting in a net downward influx in the bar trough region, followed by seaward advection along the bar's shoreward slope, and an upward outflux above the bar crest. The strongly nonuniform flow across the bar combined with the presence of anisotropic turbulence enhances turbulent production rates near the bed.

  20. Visualization of bed material movement in a simulated fluidized bed heat exchanger by neutron radiography

    International Nuclear Information System (INIS)

    Umekawa, Hisashi; Ozawa, Mamoru; Takenaka, Nobuyuki; Matsubayashi, Masahito

    1999-01-01

    The bulk movement of fluidized bed material was visualized by neutron radiography by introducing tracers into the bed materials. The simulated fluidized bed consisted of aluminum plates, and the bed material was sand of 99.7% SiO 2 (mean diameter: 0.218 mm, density: 2555 kg/m 3 ). Both materials were almost transparent to neutrons. Then the sand was colored by the contamination of the sand coated by CdSO 4 . Tracer particles of about 2 mm diameter were made by the B 4 C, bonded by the vinyl resin. The tracer was about ten times as large as the particle of fluidized bed material, but the traceability was enough to observe the bed-material bulk movement owing to the large effective viscosity of the fluidized bed. The visualized images indicated that the bubbles and/or wakes were important mechanism of the behavior of the fluidized bed movement

  1. VanderLaan Circulant Type Matrices

    Directory of Open Access Journals (Sweden)

    Hongyan Pan

    2015-01-01

    Full Text Available Circulant matrices have become a satisfactory tools in control methods for modern complex systems. In the paper, VanderLaan circulant type matrices are presented, which include VanderLaan circulant, left circulant, and g-circulant matrices. The nonsingularity of these special matrices is discussed by the surprising properties of VanderLaan numbers. The exact determinants of VanderLaan circulant type matrices are given by structuring transformation matrices, determinants of well-known tridiagonal matrices, and tridiagonal-like matrices. The explicit inverse matrices of these special matrices are obtained by structuring transformation matrices, inverses of known tridiagonal matrices, and quasi-tridiagonal matrices. Three kinds of norms and lower bound for the spread of VanderLaan circulant and left circulant matrix are given separately. And we gain the spectral norm of VanderLaan g-circulant matrix.

  2. Metabolic Resistance in Bed Bugs

    Directory of Open Access Journals (Sweden)

    Omprakash Mittapalli

    2011-03-01

    Full Text Available Blood-feeding insects have evolved resistance to various insecticides (organochlorines, pyrethroids, carbamates, etc. through gene mutations and increased metabolism. Bed bugs (Cimex lectularius are hematophagous ectoparasites that are poised to become one of the major pests in households throughout the United States. Currently, C. lectularius has attained a high global impact status due to its sudden and rampant resurgence. Resistance to pesticides is one factor implicated in this phenomenon. Although much emphasis has been placed on target sensitivity, little to no knowledge is available on the role of key metabolic players (e.g., cytochrome P450s and glutathione S-transferases towards pesticide resistance in C. lectularius. In this review, we discuss different modes of resistance (target sensitivity, penetration resistance, behavioral resistance, and metabolic resistance with more emphasis on metabolic resistance.

  3. Debridement and wound bed preparation.

    Science.gov (United States)

    Falabella, Anna F

    2006-01-01

    Debridement can play a vital role in wound bed preparation and the removal of barriers that impair wound healing. In accordance with the TIME principles, debridement can help remove nonviable tissue, control inflammation or infection, decrease excess moisture, and stimulate a nonadvancing wound edge. There are many types of debridement, each with a set of advantages and disadvantages that must be clearly understood by the healthcare team. Failure to use the correct debridement method for a given type of wound may lead to further delays in healing, increase patient suffering, and unnecessarily increase the cost of care. This review article discusses the various methods of debridement, describes currently available debriding agents, evaluates the clinical data regarding their efficacy and safety, and describes strategies for the management of problematic nonhealing wounds.

  4. Particle Bed Reactor engine technology

    Science.gov (United States)

    Sandler, S.; Feddersen, R.

    1992-03-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology.

  5. Particle Bed Reactor engine technology

    International Nuclear Information System (INIS)

    Sandler, S.; Feddersen, R.

    1992-01-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology. 4 refs

  6. Bedømmelsesformer inden for AMU

    DEFF Research Database (Denmark)

    Helms, Niels Henrik; Løfgreen, Lars Bo

    Sigtet med denne rapport om bedømmelse i AMU-regi er dels at indsamle dokumentation fra praksiserfaringer baseret på udvalgte TUP-projekter, og dels at beskrive national og international forskning på bedømmelses- og evalueringsområdet. Denne indsamling og beskrivelse vil lægge op til en diskussio...

  7. Bed-levelling experiments with suspended load

    NARCIS (Netherlands)

    Talmon, A.M.; De Graaff, J.

    1991-01-01

    Bed-levelling experiments are conducted in a straight laboratory channel. The experiments involve a significant fraction of suspended sediment transport. The purpose of the experiments is to provide data for modelling of the direction of sediment transport on a transverse sloping alluvial river bed,

  8. Flue Gas Emissions from Fluidized Bed Combustion

    NARCIS (Netherlands)

    Bramer, E.A.; Valk, M.

    1995-01-01

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

  9. Multiphase flow in spout fluidized bed granulators

    NARCIS (Netherlands)

    Buijtenen, van M.S.

    2011-01-01

    Spout fluidized beds are frequently used for the production of granules or particles through granulation, which are widely applied, for example, in the production of detergents, pharmaceuticals, food and fertilizers (M¨orl et al. 2007). Spout fluidized beds have a number of advantageous properties,

  10. 1 The Effect of Camber Bed Drainage

    African Journals Online (AJOL)

    User

    The Effect of Camber Bed Drainage Landforms on Soil. Nutrient Distribution and Grain Yield of Maize on the Vertisols ... The Vertisols of the Accra Plains of Ghana are water logged after significant rainfall ... Excess application of 15-15-15 NPK and sulphate of ammonia fertilizers (150% .... beds, before planting and nutrient.

  11. Print a Bed Bug Card - (Single Cards)

    Science.gov (United States)

    Two sets of business-card-sized lists of tips for recognizing bed bugs and the signs of an infestation, including a photo of bed bugs to assist identification. One card is for general use around home or office, the other for travelers.

  12. Uranium bed oxidation vacuum process system

    International Nuclear Information System (INIS)

    McLeland, H.L.

    1977-01-01

    Deuterium and tritium gases are occluded in uranium powder for release into neutron generator tubes. The uranium powder is contained in stainless steel bottles, termed ''beds.'' If these beds become damaged, the gases must be removed and the uranium oxidized in order not to be flammable before shipment to ERDA disposal grounds. This paper describes the system and methods designed for the controlled degassing and oxidation process. The system utilizes sputter-ion, cryo-sorption and bellows pumps for removing the gases from the heated source bed. Removing the tritium gas is complicated by the shielding effect of helium-3, a byproduct of tritium decay. This effect is minimized by incremental pressure changes, or ''batch'' processing. To prevent runaway exothermic reaction, oxidation of the uranium bed is also done incrementally, or by ''batch'' processing, rather than by continuous flow. The paper discusses in detail the helium-3 shielding effect, leak checks that must be made during processing, bed oxidation, degree of gas depletion, purity of gases sorbed from beds, radioactivity of beds, bed disposal and system renovation

  13. Bond Graph Model of Cerebral Circulation: Toward Clinically Feasible Systemic Blood Flow Simulations

    Science.gov (United States)

    Safaei, Soroush; Blanco, Pablo J.; Müller, Lucas O.; Hellevik, Leif R.; Hunter, Peter J.

    2018-01-01

    We propose a detailed CellML model of the human cerebral circulation that runs faster than real time on a desktop computer and is designed for use in clinical settings when the speed of response is important. A lumped parameter mathematical model, which is based on a one-dimensional formulation of the flow of an incompressible fluid in distensible vessels, is constructed using a bond graph formulation to ensure mass conservation and energy conservation. The model includes arterial vessels with geometric and anatomical data based on the ADAN circulation model. The peripheral beds are represented by lumped parameter compartments. We compare the hemodynamics predicted by the bond graph formulation of the cerebral circulation with that given by a classical one-dimensional Navier-Stokes model working on top of the whole-body ADAN model. Outputs from the bond graph model, including the pressure and flow signatures and blood volumes, are compared with physiological data. PMID:29551979

  14. Measurement of the bed material of gravel-bed rivers

    Science.gov (United States)

    Milhous, R.T.; ,

    2002-01-01

    The measurement of the physical properties of a gravel-bed river is important in the calculation of sediment transport and physical habitat values for aquatic animals. These properties are not always easy to measure. One recent report on flushing of fines from the Klamath River did not contain information on one location because the grain size distribution of the armour could not be measured on a dry river bar. The grain size distribution could have been measured using a barrel sampler and converting the measurements to the same as would have been measured if a dry bar existed at the site. In another recent paper the porosity was calculated from an average value relation from the literature. The results of that paper may be sensitive to the actual value of porosity. Using the bulk density sampling technique based on a water displacement process presented in this paper the porosity could have been calculated from the measured bulk density. The principle topics of this paper are the measurement of the size distribution of the armour, and measurement of the porosity of the substrate. The 'standard' method of sampling of the armour is to do a Wolman-type count of the armour on a dry section of the river bed. When a dry bar does not exist the armour in an area of the wet streambed is to sample and the measurements transformed analytically to the same type of results that would have been obtained from the standard Wolman procedure. A comparison of the results for the San Miguel River in Colorado shows significant differences in the median size of the armour. The method use to determine the porosity is not 'high-tech' and there is a need improve knowledge of the porosity because of the importance of porosity in the aquatic ecosystem. The technique is to measure the in-situ volume of a substrate sample by measuring the volume of a frame over the substrate and then repeated the volume measurement after the sample is obtained from within the frame. The difference in the

  15. Continuous austempering fluidized bed furnace. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, M.N. [Lamar Univ., Beaumont, TX (United States). Dept. of Mechanical Engineering

    1997-09-23

    The intended objective of this project was to show the benefits of using a fluidized bed furnace for austenitizing and austempering of steel castings in a continuous manner. The division of responsibilities was as follows: (1) design of the fluidized bed furnace--Kemp Development Corporation; (2) fabrication of the fluidized bed furnace--Quality Electric Steel, Inc.; (3) procedure for austempering of steel castings, analysis of the results after austempering--Texas A and M University (Texas Engineering Experiment Station). The Department of Energy provided funding to Texas A and M University and Kemp Development Corporation. The responsibility of Quality Electric Steel was to fabricate the fluidized bed, make test castings and perform austempering of the steel castings in the fluidized bed, at their own expense. The project goals had to be reviewed several times due to financial constraints and technical difficulties encountered during the course of the project. The modifications made and the associated events are listed in chronological order.

  16. Does Bedding Affect the Airway and Allergy?

    Directory of Open Access Journals (Sweden)

    RW Siebers

    2011-03-01

    Full Text Available Various cross-sectional and longitudinal studies have suggested that synthetic bedding is associated with asthma, allergic rhinitis and eczema while feather bedding seems to be protective. Synthetic bedding items have higher house dust mite allergen levels than feather bedding items. This is possibly the mechanism involved although fungal and bacterial proinflammatory compounds and volatile organic compounds may play a role. In this review we present and discuss the epidemiological evidence and suggest possible mechanisms. Primary intervention studies are required to show whether feather bedding is protective for the development of childhood asthma and allergic diseases while secondary intervention studies are required to potentially reduce symptoms and medication use in subjects with established disease.

  17. Does bedding affect the airway and allergy?

    Science.gov (United States)

    Siebers, R W; Crane, J

    2011-04-01

    Various cross-sectional and longitudinal studies have suggested that synthetic bedding is associated with asthma, allergic rhinitis and eczema while feather bedding seems to be protective. Synthetic bedding items have higher house dust mite allergen levels than feather bedding items. This is possibly the mechanism involved although fungal and bacterial proinflammatory compounds and volatile organic compounds may play a role. In this review we present and discuss the epidemiological evidence and suggest possible mechanisms. Primary intervention studies are required to show whether feather bedding is protective for the development of childhood asthma and allergic diseases while secondary intervention studies are required to potentially reduce symptoms and medication use in subjects with established disease.

  18. Journalism as Cultures of Circulation

    DEFF Research Database (Denmark)

    Bødker, Henrik

    2013-01-01

    The universe of journalism has always consisted of interspersed texts, meanings and practices. Yet, much journalism research has often isolated either texts and/or contexts and as such assumed relations between professional practices, informed (rational) readers and (conceived) core texts...... of journalism. It is, however, more important than ever to shift attention away from texts to the processes through which they are circulated. This is partly because the many cultural forms of journalism (textual, institutional, technological, material, behavioural and imagined) are undergoing significant......, likes, comments, searches, journalist roles, writing and reading positions and identities etc. Such forms will be traced within the mediation of a specific event with the overall aim of beginning a theorization of the landscape of journalism as highly interrelated cultures of circulation....

  19. Radioisotopic evaluation of portal circulation

    International Nuclear Information System (INIS)

    Maliska, C.; Rosenthal, D.

    1986-01-01

    The use of a radio-tracer of portal circulation through the intestine, should prevent cruel punctures in the portal-vein or spleen as it is usually the case with traditional methods in the study of portal-system. The absorption of I-131 and Tc-99m, previously cheked in rabbits presented similar results in dogs. The time of circulation between terminal large-intestine and the liver (t-RF) was determined by external counting at hepatic level by recording radioactivity variation-time. In healthy animals the t-RF was from 20to 60 seconds, with average time of 42 seconds. In 2 animals with partial binding of portal-vein the t-RF went up to 110 and 120 seconds. (Author) [pt

  20. Ocean circulation generated magnetic signals

    DEFF Research Database (Denmark)

    Manoj, C.; Kuvshinov, A.; Maus, S.

    2006-01-01

    Conducting ocean water, as it flows through the Earth's magnetic field, generates secondary electric and magnetic fields. An assessment of the ocean-generated magnetic fields and their detectability may be of importance for geomagnetism and oceanography. Motivated by the clear identification...... of ocean tidal signatures in the CHAMP magnetic field data we estimate the ocean magnetic signals of steady flow using a global 3-D EM numerical solution. The required velocity data are from the ECCO ocean circulation experiment and alternatively from the OCCAM model for higher resolution. We assume...... of the magnetic field, as compared to the ECCO simulation. Besides the expected signatures of the global circulation patterns, we find significant seasonal variability of ocean magnetic signals in the Indian and Western Pacific Oceans. Compared to seasonal variation, interannual variations produce weaker signals....