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The implication of mineral coalescence behaviour on ash formation and ash deposition during pulverised coal combustion
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02/01451 wall
Method for reducing carbon deposit on coke oven
Konda, T. Jpn. Kokai Tokkyo Koho JP 2001 294,869 (CI. C10B43/14), 23 Oct 2001, Appl. 2000/109,284, 11 Apr 2000. 4. (In Japanese) The method is carried out by charging O-containing plastic (e.g. PET) into the coke oven on the top of the coal charge.
02/01452 Microwave induced reactions of sulfur dioxide and nitrogen oxides in char and anthracite bed Chang, Y.C. and Dong, S.K. Carbon, 2001, 39, (8), 1159-1166. Microwaves applied to a pyrolytic carbon matrix enhance the chemical reactions of nitric oxide (NO) and sulfur dioxide (SO2) with carbon to produce nitrogen, sulfur, and carbon dioxide. These microwaveinduced reactions were investigated to find the feasibility of applying microwaves to directly destroy NO and SO2 in the combustion product gases or to minimize the formation of these pollutants during combustion process. The char produced from Wyoming subbituminous coal by the FMC Coke Plant in Kemmerer, Wyoming and Korean anthracite coal are an excellent microwave absorber and were used in this investigation as pyrolytic carbon sources. A complete destruction of NO and SO2 was achieved by microwaves in both char and anthracite bed. An addition of oxygen to the inlet nitrogen stream up to 10% did n o t affect NO and SO2 reactions with carbon•
02/01453 Nitrogen transformations during secondary coal pyrolysis Zhang, H. and Fletcher, T.H. Prepr. Syrup. - Am. Chem. Soc., Div. Fuel Chem., 2001, 46, (1), 138-140. Nitrogen release and transformations during air-staged coal combustion is studied. Nitrogen release is inherently related to mass release during the early stage of devolatilization. In addition, a strong rank dependence of the total N release on coal rank is also observed. During secondary pyrolysis, and enrichment of N in tar was 1st observed, followed by subsequently rapid N release, and finally a much lower rate of N release from soot. The reactivity of the nitrogen functionalities in tar was nearly coal independent during secondary reaction. A special type Of quaternary N may be responsible for the earlier release of NH3 than HCN at low temperatures for low tank coals. However, significant quantities of NH3 at higher temperatures seem to be formed from secondary reactions of HCN and tar.
02/01454 Parametric study of the column oil agglomeration of fly ash Gray, M.L. et al. Fuel, 2001, 80, (6), 867-871~ A promising oil agglomeration process has been developed for the beneficiation of fly ash using a 6-ft agglomeration column. Carbon concentrates have been isolated in recoveries greater than 60% and purities of 55-70%. The parameters studied include agitation speeds, airflow rates, slurry feed rates, solvent/ash ratios, and the use of various solvents as agglomerating agents. The effects of these variables on the quality of separation are discussed.
02/01455 Power station fly ash - a review of value-added utilization outside of the construction industry lyer, R.S. and Scott, J.A. Resources, Conservation and Recycling, 2001, 31, (3), 217-228. The disposal of fly ash from coal-fired power stations causes significant economic and environmental problems. A relatively small percentage of the material finds application as an ingredient in cement and other construction products, but the vast majority of material generated each year is held in ash dams or similar dumps. This unproductive use of land and the associated long-term financial burden of maintenance has led to realization that alternative uses for fly ash as a value-added product beyond incorporation in construction materials are needed. Utilization of fly ash in such areas as novel materials, waste management, recovery of metals and agriculture is reviewed in this article with the aim of looking at new areas that will expand the positive reuse of fly ash, thereby helping to reduce the environmental and economic impacts of disposal.
02/01456 SO= adsorption by activated carbons with various burnoffs obtained from a bituminous coal Davini, P. Carbon, 2001, 39, (9), 1387-1393. Activated carbons, obtained from pyrolysis and COz activation of both a bituminous coal and its reduced ash content derivative produced by HCI and HF treatment, were used to show that SO2 sorbent characteristics are improved by increasing their degree of burnoff and are related to their content of surface sites with acidic and basic features, their surface area, and their pore size distribution. Active carbons with reduced ash content also show better SO2 sorption properties at lower burnoff values and a better retention of their initial SO2 sorbent activity after ten adsorption--desorption cycles. Their improved behaviour is related to be presence of pores with larger dimensions and to a redistribution of the metals in the original mineral matter on the carbonaceous matrices induced by acid washing.
By-products related to fuels
02/01457 Study on solvent extraction experiments of bituminous coal with cracking by-product of petroleum Yu, H. et al. Shandong Keji Daxue Xuebao, Ziran Kexueban, 2001, 20, (1), 37--40, 60. (In Chinese) •Solvent extraction of Yanzhou bituminous coal with split byproducts of petroleum was investigated under mild conditions on the basis of general solvent extraction experiments. The main influencing factors of extraction yield, such as temperature, time of extraction and solventcoal ratio and the effect on additives, solvent extraction of pretreatmerit coal and second-extraction of extracted coal have been studied. The results show: (1) the split byproduct of petroleum is an efficient solvent for coal extraction: (2) the suitable conditions of extraction are that temperature is 150°C, solvent-coal ratio is 2:1, extraction time is 1.5h; (3) additives of hydrochloric acid or nitric acid added during extraction could improve extraction yield of coal; (4) the pretreatment of coal with dilutent HNO3 before extraction could greatly increase the yield of coal extraction; (5) the higher total extraction yield could be obtained with two times extraction. This study can help development of coal liquefaction and pure coal preparation.
02/01458 The fate of trace elements in a large coal-fired power plant Llorens, J.F. et al. Environ. Geol. (Berlin, Get.), 2001, 40, (4/5), 409416. A quick approach is proposed to evaluate the environmental fate of trace elements in coal-fired power plants. It is based on the analysis of feed coal and solid combustion byproducts, together with the leachates of the latter. The application of this method in a 1050 MW power plant from NE Spain shows that: (1) Ba, Ce, Co, Cs, Cu, Dy, Ga, Ge, La, Lu, Mn, Ni, Rb, Sr, Tb, Th, Y, Yb, Zn and Zr were retained in the solid wastes; (2) As, B, Be, Cd, Cr, Li, Mo, Pb, Sb, Sn, Ta, TI, U, V and W were only partially retained in the solid wastes; and (3) Hg and Se were primarily emitted to the atmosphere.
02/01459 The implication of mineral coalescence behaviour on ash formation and ash deposition during puIverised coal combustion Yah, L. et al. Fuel, 2001, 80, (9), 1333-1340. In modelling the fate of minerals of pulverized coal in coal-fired boilers, ash formation is a primary step that decides ash particle size distribution and composition. Frequently, two extreme schemes have been used regarding mineral coalescence behaviour within individual char particles, i.e. no coalescence and full coalescence. However, their implications on ash deposition and thermal performance have not been investigated. In the present paper, the implications of coalescence of included minerals on ash character and subsequent ash deposition are demonstrated by means of an ash formation model and an ash deposition model. The simulated results in a cylindrical furnace for an Australian bituminous coal indicate that ash deposition and thermal performance are significantly influenced by the coalescence behaviour of included minerals.
02/01460 The influence of calcined limestone on NOx and N20 emissions from char combustion in fluidized bed combustors Liu, H. and Gibbs, B.M. Fuel, 2001, 80, (9), 1211-1215. Limestone addition to a coal-fired fluidized bed combustor usually results in an increase in NO/NO.,. emissions and a decrease in N20 emissions. This observation has been explained in the literature by the effect of limestone on: (i) the conversion of coal volatile-N to NO/NO~ and N20; (ii) the decomposition of N20: and (iii) the pool of H, OH and/or O radicals due to sulphur capture. Since char-N is also an important source of N O / N O , and N 2 0 under fluidized bed combustion conditions, any effect of calcined limestone on the conversion of charN to NO/NOx and N20 can also contribute to the above observation. The effect of calcined limestone on the conversion of volatile-N species, i.e. NH3 and HCN has been well documented. However, so far few studies have studied the effect of limestone on the conversion of char-N under fluidized bed combustion conditions. In this study, a series of batch-type char combustion tests was carried out in a bench-scale bubbling fluidized bed combustor with different bed materials. These tests reveal that in addition to reducing N20 emissions from char combustion, calcined limestone also enhances the conversion o f c h a r - N to NO/NOx similar to the case of volatile-N. Possible reaction mechanisms to explain the experimental results of char combustion tests have been discussed.
02/01461 The influence of SO2 level and operating conditions on NOx and N=O emissions during fluidised bed combustion of coals Miecio, F. et al. Fuel, 2001, 80, (11), 1555-1566. An experimental study on interactions between tiitrogen oxides emissions in the presence of SO2 is proposed. Two different coals were burnt in a laboratory-scale fluidized bed (FB) unit in air and in an artificial atmosphere of O2/N2/SO2. The change of operating variables
Fuel and Energy Abstracts May 2002
187
02/01451 wall
Method for reducing carbon deposit on coke oven
Konda, T. Jpn. Kokai Tokkyo Koho JP 2001 294,869 (CI. C10B43/14), 23 Oct 2001, Appl. 2000/109,284, 11 Apr 2000. 4. (In Japanese) The method is carried out by charging O-containing plastic (e.g. PET) into the coke oven on the top of the coal charge.
02/01452 Microwave induced reactions of sulfur dioxide and nitrogen oxides in char and anthracite bed Chang, Y.C. and Dong, S.K. Carbon, 2001, 39, (8), 1159-1166. Microwaves applied to a pyrolytic carbon matrix enhance the chemical reactions of nitric oxide (NO) and sulfur dioxide (SO2) with carbon to produce nitrogen, sulfur, and carbon dioxide. These microwaveinduced reactions were investigated to find the feasibility of applying microwaves to directly destroy NO and SO2 in the combustion product gases or to minimize the formation of these pollutants during combustion process. The char produced from Wyoming subbituminous coal by the FMC Coke Plant in Kemmerer, Wyoming and Korean anthracite coal are an excellent microwave absorber and were used in this investigation as pyrolytic carbon sources. A complete destruction of NO and SO2 was achieved by microwaves in both char and anthracite bed. An addition of oxygen to the inlet nitrogen stream up to 10% did n o t affect NO and SO2 reactions with carbon•
02/01453 Nitrogen transformations during secondary coal pyrolysis Zhang, H. and Fletcher, T.H. Prepr. Syrup. - Am. Chem. Soc., Div. Fuel Chem., 2001, 46, (1), 138-140. Nitrogen release and transformations during air-staged coal combustion is studied. Nitrogen release is inherently related to mass release during the early stage of devolatilization. In addition, a strong rank dependence of the total N release on coal rank is also observed. During secondary pyrolysis, and enrichment of N in tar was 1st observed, followed by subsequently rapid N release, and finally a much lower rate of N release from soot. The reactivity of the nitrogen functionalities in tar was nearly coal independent during secondary reaction. A special type Of quaternary N may be responsible for the earlier release of NH3 than HCN at low temperatures for low tank coals. However, significant quantities of NH3 at higher temperatures seem to be formed from secondary reactions of HCN and tar.
02/01454 Parametric study of the column oil agglomeration of fly ash Gray, M.L. et al. Fuel, 2001, 80, (6), 867-871~ A promising oil agglomeration process has been developed for the beneficiation of fly ash using a 6-ft agglomeration column. Carbon concentrates have been isolated in recoveries greater than 60% and purities of 55-70%. The parameters studied include agitation speeds, airflow rates, slurry feed rates, solvent/ash ratios, and the use of various solvents as agglomerating agents. The effects of these variables on the quality of separation are discussed.
02/01455 Power station fly ash - a review of value-added utilization outside of the construction industry lyer, R.S. and Scott, J.A. Resources, Conservation and Recycling, 2001, 31, (3), 217-228. The disposal of fly ash from coal-fired power stations causes significant economic and environmental problems. A relatively small percentage of the material finds application as an ingredient in cement and other construction products, but the vast majority of material generated each year is held in ash dams or similar dumps. This unproductive use of land and the associated long-term financial burden of maintenance has led to realization that alternative uses for fly ash as a value-added product beyond incorporation in construction materials are needed. Utilization of fly ash in such areas as novel materials, waste management, recovery of metals and agriculture is reviewed in this article with the aim of looking at new areas that will expand the positive reuse of fly ash, thereby helping to reduce the environmental and economic impacts of disposal.
02/01456 SO= adsorption by activated carbons with various burnoffs obtained from a bituminous coal Davini, P. Carbon, 2001, 39, (9), 1387-1393. Activated carbons, obtained from pyrolysis and COz activation of both a bituminous coal and its reduced ash content derivative produced by HCI and HF treatment, were used to show that SO2 sorbent characteristics are improved by increasing their degree of burnoff and are related to their content of surface sites with acidic and basic features, their surface area, and their pore size distribution. Active carbons with reduced ash content also show better SO2 sorption properties at lower burnoff values and a better retention of their initial SO2 sorbent activity after ten adsorption--desorption cycles. Their improved behaviour is related to be presence of pores with larger dimensions and to a redistribution of the metals in the original mineral matter on the carbonaceous matrices induced by acid washing.
By-products related to fuels
02/01457 Study on solvent extraction experiments of bituminous coal with cracking by-product of petroleum Yu, H. et al. Shandong Keji Daxue Xuebao, Ziran Kexueban, 2001, 20, (1), 37--40, 60. (In Chinese) •Solvent extraction of Yanzhou bituminous coal with split byproducts of petroleum was investigated under mild conditions on the basis of general solvent extraction experiments. The main influencing factors of extraction yield, such as temperature, time of extraction and solventcoal ratio and the effect on additives, solvent extraction of pretreatmerit coal and second-extraction of extracted coal have been studied. The results show: (1) the split byproduct of petroleum is an efficient solvent for coal extraction: (2) the suitable conditions of extraction are that temperature is 150°C, solvent-coal ratio is 2:1, extraction time is 1.5h; (3) additives of hydrochloric acid or nitric acid added during extraction could improve extraction yield of coal; (4) the pretreatment of coal with dilutent HNO3 before extraction could greatly increase the yield of coal extraction; (5) the higher total extraction yield could be obtained with two times extraction. This study can help development of coal liquefaction and pure coal preparation.
02/01458 The fate of trace elements in a large coal-fired power plant Llorens, J.F. et al. Environ. Geol. (Berlin, Get.), 2001, 40, (4/5), 409416. A quick approach is proposed to evaluate the environmental fate of trace elements in coal-fired power plants. It is based on the analysis of feed coal and solid combustion byproducts, together with the leachates of the latter. The application of this method in a 1050 MW power plant from NE Spain shows that: (1) Ba, Ce, Co, Cs, Cu, Dy, Ga, Ge, La, Lu, Mn, Ni, Rb, Sr, Tb, Th, Y, Yb, Zn and Zr were retained in the solid wastes; (2) As, B, Be, Cd, Cr, Li, Mo, Pb, Sb, Sn, Ta, TI, U, V and W were only partially retained in the solid wastes; and (3) Hg and Se were primarily emitted to the atmosphere.
02/01459 The implication of mineral coalescence behaviour on ash formation and ash deposition during puIverised coal combustion Yah, L. et al. Fuel, 2001, 80, (9), 1333-1340. In modelling the fate of minerals of pulverized coal in coal-fired boilers, ash formation is a primary step that decides ash particle size distribution and composition. Frequently, two extreme schemes have been used regarding mineral coalescence behaviour within individual char particles, i.e. no coalescence and full coalescence. However, their implications on ash deposition and thermal performance have not been investigated. In the present paper, the implications of coalescence of included minerals on ash character and subsequent ash deposition are demonstrated by means of an ash formation model and an ash deposition model. The simulated results in a cylindrical furnace for an Australian bituminous coal indicate that ash deposition and thermal performance are significantly influenced by the coalescence behaviour of included minerals.
02/01460 The influence of calcined limestone on NOx and N20 emissions from char combustion in fluidized bed combustors Liu, H. and Gibbs, B.M. Fuel, 2001, 80, (9), 1211-1215. Limestone addition to a coal-fired fluidized bed combustor usually results in an increase in NO/NO.,. emissions and a decrease in N20 emissions. This observation has been explained in the literature by the effect of limestone on: (i) the conversion of coal volatile-N to NO/NO~ and N20; (ii) the decomposition of N20: and (iii) the pool of H, OH and/or O radicals due to sulphur capture. Since char-N is also an important source of N O / N O , and N 2 0 under fluidized bed combustion conditions, any effect of calcined limestone on the conversion of charN to NO/NOx and N20 can also contribute to the above observation. The effect of calcined limestone on the conversion of volatile-N species, i.e. NH3 and HCN has been well documented. However, so far few studies have studied the effect of limestone on the conversion of char-N under fluidized bed combustion conditions. In this study, a series of batch-type char combustion tests was carried out in a bench-scale bubbling fluidized bed combustor with different bed materials. These tests reveal that in addition to reducing N20 emissions from char combustion, calcined limestone also enhances the conversion o f c h a r - N to NO/NOx similar to the case of volatile-N. Possible reaction mechanisms to explain the experimental results of char combustion tests have been discussed.
02/01461 The influence of SO2 level and operating conditions on NOx and N=O emissions during fluidised bed combustion of coals Miecio, F. et al. Fuel, 2001, 80, (11), 1555-1566. An experimental study on interactions between tiitrogen oxides emissions in the presence of SO2 is proposed. Two different coals were burnt in a laboratory-scale fluidized bed (FB) unit in air and in an artificial atmosphere of O2/N2/SO2. The change of operating variables
Fuel and Energy Abstracts May 2002
187