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Deposit Formation in a 150 MWe Utility PF-Boiler during Co-combustion of Coal and Straw
08 Steam raising (boiler operation/design) achieve a specific emission reduction. Policies to ensure a more intensive use of such relatively expensive renewable energy sources as biomass could be implemented with only small taxes and subsidies. 02/00536 Technoeconomic assessment of four biomass-tohydrogen conversion technologies Spath, P.L., Mann, M.K. Hydrogen Energy Prog. XII, Proc. World Hydrogen Energy Cons., IZfh, 1998, 3, 2057-2067. Edited by Bolcich, J.C., Veziroglu, T.N. Different technologies to convert biomass feedstocks to hydrogen were comparatively studied to determine their economic potential and to provide insight into where each technology is in its development cycle. This work is funded by the US Department of Energy’s Hydrogen Program, to provide support to the development and introduction of renewable hydrogen through the evaluation of the technical and economic aspects of various technologies. The cost of biomass-derived hydrogen, produced from four thermochemical conversion systems, was determined. The gasifier systems considered in these studies were the Texaco gasifier, the BCWFERCO indirectly-heated gasifier, and the Institute of Gas Technology direct-fired gasifier. Additionally, a generic fluid bed pyrolysis reactor was studied. Different combinations of the following operations were included in the system designs: biomass pyrolysis, biomass gasification, conventional steam reforming, and air separation. For each of the systems studied, the downstream process steps include shift conversion followed by hydrogen purification. A series of sensitivity analyses were conducted to determine the conditions under which each process is most feasible and to guide experimental efforts toward the areas that could result in the largest cost reductions. 02/00537 Thermochemical characterization of pigeon pea stalk for its efficient utilization as an energy source Katyal, SK., Iyer, P.V.R. Energy Sources, 2000, 22, (4) 363-375. Pigeon pea stalk is a widely available biomass species in India. In this article the potential use of pigeon pea stalk as a fuel source through thermochemical conversion methods such as combustion, gasification, and pyrolysis have been investigated through experimentation using a thermogravimetric analyser and pilot plant-scale equipment. It has been proposed that pigeon pea stalks can be effectively utilized in two ways. The first is to pyrolyse the material to produce value-added products such as char, tar, and fuel gas. The second alternative is to partially pyrolyse the material to remove tar-forming volatiles, followed by gasification of reactive char to generate producer gas. 02/00536 Treatment of sludges containing pulverized coal Asano, T. er al. Jpn. Kokai Tokkyo Koho JP 2000 176,490 (Cl. C02Fll/OO), 27 Jun 2000, Appl. 1998/353,640, 11 Dee 1998. 8. (In Japanese) Sludge cakes obtained by filtering and dewatering organic sludges containing pulverized coal are mixed with oils and wet-ground to give crude fuel mixtures. The process is useful for recycling of wastewater treatment sludges into fuel emulsions. 02/00539 Use of beet cassettes for biogas production. II. Pilot plant Hutnan, M. er al. Listy Cukrov. Reparske, 1999, 115, (12) 348-352. (In Slovenska) Use of waste beet cuttings from sugar production for biogas manufacture was investigated. A pilot plant was developed for anaerobic processing of the cuttings. The apparatus consisted of two stages: (1) a hydrolysation-acidification reactor and (2) a methanization reactor. Optimum process parameters were evaluated. 02/00540 Use of gasification of scrap tires in the fluidized bed for the production of energy sources Goulart, E.A. ef al. Polim.: Cienc. Tecnol., 1999, 9, (4) 123-128. (In Portuguese) The growth of the big cities, industrialization and goods consumption have forced the civilization to live with more intensive environmental degradation, threatening both nature and energy resources, besides the bigger production of gas, liquid and solid wastes. Energy planning aims to minimize wastes production as well as to stimulate both waste and sub-products re-utilization in industrial processes. To contribute to the solution of these problems, a proposal is presented of a reactor which uses scrap tyres to produce fuel oil by gasification. 02lOO541 Waste to energy activities for the surface coating industry Davern, P. surf. Coar. Ausr., 1999, 36, (8), 30-33. A review with no references discussed the current and short terms future waste disposal options available to the industry in Victoria. It reviews some of the modifications to the Prescribed Waste Regulations
in Victoria and suggests the likely future treatment requirements. The paper summarizes the advantages and some of the problems observed in supplying waste derived fuel to cement kilns.
08
STEAM RAISING Boiler operation/design
02lOO542 Boiler flue gas desulfurization system Ohtsubo, K., Matsumoto, A. Jpn. Kokai Tokkyo Koho JP 2000 84,353 (Cl. BOlD53/50), 28 Mar 2000, Appl. 1998/263,146, 17 Sep 1998. 4. (In Japanese) Induced draft fan is placed at the up- or the downstream of a desulphurization apparatus, in a system for treatment of boiler flue gas with a gas-gas heater, an electroprecipitator, a desulphurization apparatus, and a reheating gas-gas heater. The system is manufactured at low cost. 02/00543 Deposit Formation in a 150 MW, Utility PF-Boiler during Co-combustion of Coal and Straw Andersen, K.H. er al. Energy Fuels, 2000, 14, (4) 765-780. A conventional pc-fired boiler at the Danish energy company I/S Midtkraft has been converted to coal-straw co-combustion, and a 2 year demonstration programme was initiated in January 1996, addressing several aspects of coal-straw co-combustion. Deposition trials were performed as part of the demonstration programme. A maximum straw share of approximately 20% (energy base) was used in the experiments. For the deposit samples collected, a visual analysis procedure was developed and each sample evaluated according to this. In addition, a number of samples were analysed by SEM combined with energy dispersive X-ray analyses (SEM-EDX) and bulk chemical analyses. In the visual analysis, a significant increase in the amount and tenacity of the upstream deposits was observed as a function of increased straw share, exposure time, and boiler load. The chemical analyses of the deposits show increased amounts of K and S during coLcombustion, and the Fe-dominated upstream deposits formed during coal combustion are shifted toward more Ca- and Si-rich deposits during coal-straw co-combustion. However, the major part of K is observed to form K-AI silicates, which do not form problematic deposits. Co-firing straw also caused a change in the structure of the upstream deposits. During coal combustion an ordered, ‘finger’ structure of the larger particles with small particles between was observed, whereas during co-combustion a more random deposition of the larger particles among the small ones was observed. No chlorine species was observed in the deposits collected, and selective chlorine corrosion is therefore not expected to constitute a problem in co-combustion of coal and straw up to 20% straw share, for the coal types utilized in the tests. However, deposition problems could arise when burning other coals, particularly coals with a high S or alkali metal content or a low content of ash. The behaviour of K, Ca, S, and Cl was evaluated by use of thermodynamic calculations. The thermodynamically stable species agree with the observed behaviour in the experiments, i.e. formation of stable K-AI silicate species as well as KzS04 is predicted. The calculations also emphasize that the mixing between the coal and straw species is essential for the deposition behaviour, primarily by affecting the split between K-AI silicates and KzSO+ 02/00544 Ecological characteristics of TP-14A boiler redesigned for low temperature vortex combustion of brown coal Fatkullin, R.M. et al. Elektr. Sfn., 2000, 5, 18-22. (In Russian) The ecological Characteristics is studied of low-temperature, vertical, brown coal fired boiler. The aerodynamic variation of the combustionchamber scheme significantly affects the ecological characteristics of the boiler. The feeding of fraction of the air into the combustion chamber through a nozzle with bottom blowing enables to decrease the release of nitrogen oxides by 35% and maintain uniform low temperature compared to the common cocurrent boilers. The temperature of the flame tongue in the combustion chamber is =llOo”, the maximum temperature in the vortex region is 1200”, in the combustion chamber the temperature of the combustion products is 950-1000”, and the temperature at the outlet is -900”. The effect of excess air and fraction of air in bottom blowing on the concentration of nitrogen oxides is presented graphically and analysed. The efficiency of removal of sulphur dioxide from ash is significantly improved. Fuel and Energy Abstracts
January 2002
55
in Victoria and suggests the likely future treatment requirements. The paper summarizes the advantages and some of the problems observed in supplying waste derived fuel to cement kilns.
08
STEAM RAISING Boiler operation/design
02lOO542 Boiler flue gas desulfurization system Ohtsubo, K., Matsumoto, A. Jpn. Kokai Tokkyo Koho JP 2000 84,353 (Cl. BOlD53/50), 28 Mar 2000, Appl. 1998/263,146, 17 Sep 1998. 4. (In Japanese) Induced draft fan is placed at the up- or the downstream of a desulphurization apparatus, in a system for treatment of boiler flue gas with a gas-gas heater, an electroprecipitator, a desulphurization apparatus, and a reheating gas-gas heater. The system is manufactured at low cost. 02/00543 Deposit Formation in a 150 MW, Utility PF-Boiler during Co-combustion of Coal and Straw Andersen, K.H. er al. Energy Fuels, 2000, 14, (4) 765-780. A conventional pc-fired boiler at the Danish energy company I/S Midtkraft has been converted to coal-straw co-combustion, and a 2 year demonstration programme was initiated in January 1996, addressing several aspects of coal-straw co-combustion. Deposition trials were performed as part of the demonstration programme. A maximum straw share of approximately 20% (energy base) was used in the experiments. For the deposit samples collected, a visual analysis procedure was developed and each sample evaluated according to this. In addition, a number of samples were analysed by SEM combined with energy dispersive X-ray analyses (SEM-EDX) and bulk chemical analyses. In the visual analysis, a significant increase in the amount and tenacity of the upstream deposits was observed as a function of increased straw share, exposure time, and boiler load. The chemical analyses of the deposits show increased amounts of K and S during coLcombustion, and the Fe-dominated upstream deposits formed during coal combustion are shifted toward more Ca- and Si-rich deposits during coal-straw co-combustion. However, the major part of K is observed to form K-AI silicates, which do not form problematic deposits. Co-firing straw also caused a change in the structure of the upstream deposits. During coal combustion an ordered, ‘finger’ structure of the larger particles with small particles between was observed, whereas during co-combustion a more random deposition of the larger particles among the small ones was observed. No chlorine species was observed in the deposits collected, and selective chlorine corrosion is therefore not expected to constitute a problem in co-combustion of coal and straw up to 20% straw share, for the coal types utilized in the tests. However, deposition problems could arise when burning other coals, particularly coals with a high S or alkali metal content or a low content of ash. The behaviour of K, Ca, S, and Cl was evaluated by use of thermodynamic calculations. The thermodynamically stable species agree with the observed behaviour in the experiments, i.e. formation of stable K-AI silicate species as well as KzS04 is predicted. The calculations also emphasize that the mixing between the coal and straw species is essential for the deposition behaviour, primarily by affecting the split between K-AI silicates and KzSO+ 02/00544 Ecological characteristics of TP-14A boiler redesigned for low temperature vortex combustion of brown coal Fatkullin, R.M. et al. Elektr. Sfn., 2000, 5, 18-22. (In Russian) The ecological Characteristics is studied of low-temperature, vertical, brown coal fired boiler. The aerodynamic variation of the combustionchamber scheme significantly affects the ecological characteristics of the boiler. The feeding of fraction of the air into the combustion chamber through a nozzle with bottom blowing enables to decrease the release of nitrogen oxides by 35% and maintain uniform low temperature compared to the common cocurrent boilers. The temperature of the flame tongue in the combustion chamber is =llOo”, the maximum temperature in the vortex region is 1200”, in the combustion chamber the temperature of the combustion products is 950-1000”, and the temperature at the outlet is -900”. The effect of excess air and fraction of air in bottom blowing on the concentration of nitrogen oxides is presented graphically and analysed. The efficiency of removal of sulphur dioxide from ash is significantly improved. Fuel and Energy Abstracts
January 2002
55