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00051 Change in surface characteristics of coal in upgrading of low-rank coals
01
Solid fuels (preparation)
molecular products is provided by subversion of the assimilation pathways by genetic manipulation. Reports on anaerobic conversion of coal to methane are controversial and are not yet published in detail. Bioremoval of organic and inorganic sulfur in coal 98/00050 samples Gomez, F. et al. DGMK Tagungsber., 1997, 9704, (Proceedings ICCS ‘97, Volume 3), 1663-1666. The authors detail an attempt to characterize the microbial ecology of different Spanish coal samples by enrichment cultures at different growth conditions. Using their phenotypic and genotypic properties, several isolated bacteria were identified as members of the Xantomunas, Pseudomonas, Bacillus, and Thiobacillus geni. Different isolates were tested in desulfurization column experiments. The analysis of their capacity for metabolizing organic as well as inorganic S has shown their potential for industrial coal desulfurization processes. Change in surface characteristics of coal in 98/00051 upgrading of low-rank coals Ohki, A. et al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1996, 33, 181184. (In Japanese) Low-rank coals, such as Loy Yang and Yallourn coals, were upgraded by use of ‘Hot Water Drying’ (HWD) method. The effect of temperature such as hygroscopicity, functional group variation on coal properties, content, and specific surface area, was investigated. As the treatment temperature was elevated, the hygroscopicity of coal decreased along with the content of hydrophilic groups, such as hydroxyl and carbonyl groups. Coal pond fines cleaning with classifying cyclones, 98100052 spirals, and column flotation Carson, W. R. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 585-596.
Illinois Basin is the source of large reserves of coal pond fines. If these fines are used to produce coal-water slurry (CWS), fuel costs, NO, emissions and pond closure costs can be reduced. Coal fines from this region that are used to produce CWS for co-fire or re-burn may require processing, however, to attain proper particle size distribution and fuel quality. To evaluate the effectiveness of using coal cleaning technologies to control these CWS quality parameters, a simple flowsheet for recovering and processing coal pond fines was designed and tested. Coal fines processing consisted of using classifying cyclones to size at nominal minus 200 mesh, cleaning the classifying cyclone underflow using spirals, and cleaning the overflow using column froth flotation. Ash content of the clean coal from the spiral was reduced to lo%, satisfactory for use in CWS co-firing in a cyclone-fired boiler. The clean coal from column flotation may be used for re-burn in a cyclone-fired boiler or as co-fire fuel in a wall-fired or tangentially-fired boiler. Heating value recovery during laboratory-scale, pilot-scale, and commercial-scale coal cleaning testing was 80%. Degradation of Yallourn coal by mild oxidation with 98100053 hydrogen peroxide in alcohols and flash pyrolysis of the treated coals Isoda, T. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 581-584. Oxidation of Yallourn brown coal was performed at 70°C for 6-12 h with aqueous HzOz in the presence of lower alcohols. It was subsequently subjected to flash pyrolysis using an entrained-flow pyrolyser at 800°C and a Curie-point pyrolyser at 764°C. The H20Z level and alcohol added to the initial coal had a strong influence on the yield of MeOH extraction and product distributions. In the presence of alcohols, the carbon loss as CO and COz during oxidation was decreased to < 6%, with the exception oftBuOH. The MeOH-soluble of the coal was increased by oxidation. Oxalic, acetic, formic, and malonic acid were the major acids formed by oxidation. Char yield was greatly decreased and tar and BTX yields of the pyrolysis were increased by the oxidation. ‘“NMR structural analysis indicated that oxidation did not change the aromatic ring structure, but decreased the number of bridges. Depolymerization of coal by O2 oxidation followed 98100054 by acid hydrolysis Aizawa, S. et al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1996, 33, 145148. (In Japanese) In a Na2C07 aqueous solution, four low-rank coals were oxidized at a temperature of 85”C, into which oxygen gas was bubbled. The coal peroxides formed were decomposed by an acid hydrolysis. The maximum carbon conversion to volatiles was 4%. The oxidation-hydrolysis depolymerized the coals and introduced oxygen functionalities into them. The treatment also dramatically increased the extraction yield of the coals with DMF, DMSO and THFimethanol mixture up to 90% or more. The extractability was correlated to the solubility parameters of the solvents much better than to their donor numbers. The extent of C-C and C-O bond breaking had a strong influence on the increment of the extractability per amount of consumed oxygen. Development in biodesulfuriration of coal 98iOOO55 Li, G. and Hu, .I. Huaxue Jinzhan, 1997, 9, (l), 79-89. (In Chinese) Topics include bacteria used for this process, reaction mechanisms typical technological processes, and the major problems.
6
Fuel and Energy Abstracts
January 1998
and
Dewatering of fine clean coal using a high pressure 98100056 filter-a pilot plant study Parekh, B. K. and Groppo, J. G. Fluid/fart. Separate I., 1997, 10, (I), 5760. Evaluation of the Andritz Ruthner Inc. hyperbaric filter took place at the pilot-plant scale for dewatering fine coal cleaned by froth flotation. The pilot-plant scale dewatering test was conducted at solid feed rates of IOO200 Ibsih-ft* at two of Consol Inc. preparation plants. The effect of hyperbaric operating parameters and addition of various surfactants and flocculants were evaluated for dewatering of fine coal. Although addition of a flocculant increased the moisture content of the filter cake, addition of a cationic surfactant decreased the moisture content of the filter cake from 22.8 wt% to 21.4 wt%, at 3.5 bar filter pressure. Effect of heat treatment changes on swelling 98100057 treatment of coal Satsuka, T. et al. Sekitan Kagaku Kmgi Happy0 Rortbunshu, 1996, 33. 185188. (In Japanese) This work examines the effect of pre-heat treatment of Taiheiyo coal on the solvent swelling and the hydrogenolysis reaction. The coal was treated at 200°C for 1 h at different heating and cooling rates. The swelling on the treated coal and the liquefaction yield obtained from the hydrogenolysis were dependent on these heating and cooling rates. 98lOOO58 Effect of magnetite size on the coal purification process in a fluidized bed Kozanoglu, B. U. and Ramos, M. Y. Int. Technol., 1997, 8. (5). 79-85. (In Spanish) The influence of magnetite size on coal cleaning in a bubbling fluidized hed was studied. A computational model was used to predict the axial concentrations of particles in the bed. Three sizes of coal were simulated and, computer calculations with different sizes of magnetite were carried out for each. The efficiency of the process was a strong function of magnetite size. The coal-magnetite size ratio 1.80:1.45 produced the highest impurity reduction. 98100059 Effect of preheating of coal on product distributions in flash pyrolysis Morouka, S. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 577-580. Prior to pyrolysis in a Curie point pyrolyser, Illinois No. 6 and Beulah Zap lignite were preheated to SO-380°C at a rate of 5 K/min. Preheating to 200250°C increased the tar yield of Illinois No. 6 coal, while decreasing yields of inorganic and hydrocarbon gases. This is explained by an increase in local mobility of macromolecular chains by breaking H bonds. For the lignite, tar yield was decreased by the formation of covalent cross-links accompanied by decomposition of tightly H-bonded OH groups during heat treatment. At >3OO”C, tar yield increased by the mobilization of macromolecular chains. 98lOOO60 Effect of preoxidation of a semianthracite on its textural evolution to char Ruiz, B. et al. DGMK Tagungsber., 1997, 9704, (Proceedings ICCS ‘97, Volume 3). 1855-1858. The paper examines the effect of preoxidation and subsequent pyrolysis of a semianthracite on its textural development properties. A substantial increase in 0 content was displayed by the oxidized coals with a rise in true density and surface area, SCoZ_oR. Nitrogen adsorption at 77 K was not significant. The pyrolysis of the oxidized coals produced a significant decrease in the 0 content of the chars. With reference to the true density values of the chars, preoxidation seemed to have a positive effect on densification. The increase in surface areas obtained from CO2 and NZ isotherms confirmed the benefits of preoxidation. Electrolytic desulfurization of Xiaoyi coals. II. 98lOOO61 Desulfurization by electroreduction Liu, X. et al. Ranliao Huaxue Xuebao, 1997,25, (4), 363-367. (In Chinese) A Xiaoyi coal with high sulfur content was electrolytically desulfurized in an undivided batch cell. The effects of proton donor, supporting electrolyte, coal content, potential and temperature on desulfurization conversion were investigated. The optimum conditions were as follows: CzH50H:HzO = 1.8:1 (volume), BuaNBr = 0.25 molil, coal = 0.045 g/ml, E = -2.5 V (vs. SCE), and T = 310 K. During desulfurization, mild hydrogenation was observed. Enzymic depolymeriration of low-rank coal (lignite) 98100062 Hofrichter, M. et al. DGMK Tagungsber., 1997, 9704. (Proceedings ICCS ‘97, Volume 3), 1595-1598. Ligninolytic basidiomycetes can degrade low-rank coal (lignite). Extracellular Mn peroxidase (MOP) is the decisive enzyme in the depolymerization process both of coal-derived humic substances and native coal. The depolymerization of coal occurred via Mn”+ ions acting as primary mediator and can be considerably enhanced by certain thiols acting as secondary mediators. The depolymerization process leads finally to complex mixtures of fulvic acid-like compounds.
Solid fuels (preparation)
molecular products is provided by subversion of the assimilation pathways by genetic manipulation. Reports on anaerobic conversion of coal to methane are controversial and are not yet published in detail. Bioremoval of organic and inorganic sulfur in coal 98/00050 samples Gomez, F. et al. DGMK Tagungsber., 1997, 9704, (Proceedings ICCS ‘97, Volume 3), 1663-1666. The authors detail an attempt to characterize the microbial ecology of different Spanish coal samples by enrichment cultures at different growth conditions. Using their phenotypic and genotypic properties, several isolated bacteria were identified as members of the Xantomunas, Pseudomonas, Bacillus, and Thiobacillus geni. Different isolates were tested in desulfurization column experiments. The analysis of their capacity for metabolizing organic as well as inorganic S has shown their potential for industrial coal desulfurization processes. Change in surface characteristics of coal in 98/00051 upgrading of low-rank coals Ohki, A. et al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1996, 33, 181184. (In Japanese) Low-rank coals, such as Loy Yang and Yallourn coals, were upgraded by use of ‘Hot Water Drying’ (HWD) method. The effect of temperature such as hygroscopicity, functional group variation on coal properties, content, and specific surface area, was investigated. As the treatment temperature was elevated, the hygroscopicity of coal decreased along with the content of hydrophilic groups, such as hydroxyl and carbonyl groups. Coal pond fines cleaning with classifying cyclones, 98100052 spirals, and column flotation Carson, W. R. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 585-596.
Illinois Basin is the source of large reserves of coal pond fines. If these fines are used to produce coal-water slurry (CWS), fuel costs, NO, emissions and pond closure costs can be reduced. Coal fines from this region that are used to produce CWS for co-fire or re-burn may require processing, however, to attain proper particle size distribution and fuel quality. To evaluate the effectiveness of using coal cleaning technologies to control these CWS quality parameters, a simple flowsheet for recovering and processing coal pond fines was designed and tested. Coal fines processing consisted of using classifying cyclones to size at nominal minus 200 mesh, cleaning the classifying cyclone underflow using spirals, and cleaning the overflow using column froth flotation. Ash content of the clean coal from the spiral was reduced to lo%, satisfactory for use in CWS co-firing in a cyclone-fired boiler. The clean coal from column flotation may be used for re-burn in a cyclone-fired boiler or as co-fire fuel in a wall-fired or tangentially-fired boiler. Heating value recovery during laboratory-scale, pilot-scale, and commercial-scale coal cleaning testing was 80%. Degradation of Yallourn coal by mild oxidation with 98100053 hydrogen peroxide in alcohols and flash pyrolysis of the treated coals Isoda, T. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 581-584. Oxidation of Yallourn brown coal was performed at 70°C for 6-12 h with aqueous HzOz in the presence of lower alcohols. It was subsequently subjected to flash pyrolysis using an entrained-flow pyrolyser at 800°C and a Curie-point pyrolyser at 764°C. The H20Z level and alcohol added to the initial coal had a strong influence on the yield of MeOH extraction and product distributions. In the presence of alcohols, the carbon loss as CO and COz during oxidation was decreased to < 6%, with the exception oftBuOH. The MeOH-soluble of the coal was increased by oxidation. Oxalic, acetic, formic, and malonic acid were the major acids formed by oxidation. Char yield was greatly decreased and tar and BTX yields of the pyrolysis were increased by the oxidation. ‘“NMR structural analysis indicated that oxidation did not change the aromatic ring structure, but decreased the number of bridges. Depolymerization of coal by O2 oxidation followed 98100054 by acid hydrolysis Aizawa, S. et al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1996, 33, 145148. (In Japanese) In a Na2C07 aqueous solution, four low-rank coals were oxidized at a temperature of 85”C, into which oxygen gas was bubbled. The coal peroxides formed were decomposed by an acid hydrolysis. The maximum carbon conversion to volatiles was 4%. The oxidation-hydrolysis depolymerized the coals and introduced oxygen functionalities into them. The treatment also dramatically increased the extraction yield of the coals with DMF, DMSO and THFimethanol mixture up to 90% or more. The extractability was correlated to the solubility parameters of the solvents much better than to their donor numbers. The extent of C-C and C-O bond breaking had a strong influence on the increment of the extractability per amount of consumed oxygen. Development in biodesulfuriration of coal 98iOOO55 Li, G. and Hu, .I. Huaxue Jinzhan, 1997, 9, (l), 79-89. (In Chinese) Topics include bacteria used for this process, reaction mechanisms typical technological processes, and the major problems.
6
Fuel and Energy Abstracts
January 1998
and
Dewatering of fine clean coal using a high pressure 98100056 filter-a pilot plant study Parekh, B. K. and Groppo, J. G. Fluid/fart. Separate I., 1997, 10, (I), 5760. Evaluation of the Andritz Ruthner Inc. hyperbaric filter took place at the pilot-plant scale for dewatering fine coal cleaned by froth flotation. The pilot-plant scale dewatering test was conducted at solid feed rates of IOO200 Ibsih-ft* at two of Consol Inc. preparation plants. The effect of hyperbaric operating parameters and addition of various surfactants and flocculants were evaluated for dewatering of fine coal. Although addition of a flocculant increased the moisture content of the filter cake, addition of a cationic surfactant decreased the moisture content of the filter cake from 22.8 wt% to 21.4 wt%, at 3.5 bar filter pressure. Effect of heat treatment changes on swelling 98100057 treatment of coal Satsuka, T. et al. Sekitan Kagaku Kmgi Happy0 Rortbunshu, 1996, 33. 185188. (In Japanese) This work examines the effect of pre-heat treatment of Taiheiyo coal on the solvent swelling and the hydrogenolysis reaction. The coal was treated at 200°C for 1 h at different heating and cooling rates. The swelling on the treated coal and the liquefaction yield obtained from the hydrogenolysis were dependent on these heating and cooling rates. 98lOOO58 Effect of magnetite size on the coal purification process in a fluidized bed Kozanoglu, B. U. and Ramos, M. Y. Int. Technol., 1997, 8. (5). 79-85. (In Spanish) The influence of magnetite size on coal cleaning in a bubbling fluidized hed was studied. A computational model was used to predict the axial concentrations of particles in the bed. Three sizes of coal were simulated and, computer calculations with different sizes of magnetite were carried out for each. The efficiency of the process was a strong function of magnetite size. The coal-magnetite size ratio 1.80:1.45 produced the highest impurity reduction. 98100059 Effect of preheating of coal on product distributions in flash pyrolysis Morouka, S. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 577-580. Prior to pyrolysis in a Curie point pyrolyser, Illinois No. 6 and Beulah Zap lignite were preheated to SO-380°C at a rate of 5 K/min. Preheating to 200250°C increased the tar yield of Illinois No. 6 coal, while decreasing yields of inorganic and hydrocarbon gases. This is explained by an increase in local mobility of macromolecular chains by breaking H bonds. For the lignite, tar yield was decreased by the formation of covalent cross-links accompanied by decomposition of tightly H-bonded OH groups during heat treatment. At >3OO”C, tar yield increased by the mobilization of macromolecular chains. 98lOOO60 Effect of preoxidation of a semianthracite on its textural evolution to char Ruiz, B. et al. DGMK Tagungsber., 1997, 9704, (Proceedings ICCS ‘97, Volume 3). 1855-1858. The paper examines the effect of preoxidation and subsequent pyrolysis of a semianthracite on its textural development properties. A substantial increase in 0 content was displayed by the oxidized coals with a rise in true density and surface area, SCoZ_oR. Nitrogen adsorption at 77 K was not significant. The pyrolysis of the oxidized coals produced a significant decrease in the 0 content of the chars. With reference to the true density values of the chars, preoxidation seemed to have a positive effect on densification. The increase in surface areas obtained from CO2 and NZ isotherms confirmed the benefits of preoxidation. Electrolytic desulfurization of Xiaoyi coals. II. 98lOOO61 Desulfurization by electroreduction Liu, X. et al. Ranliao Huaxue Xuebao, 1997,25, (4), 363-367. (In Chinese) A Xiaoyi coal with high sulfur content was electrolytically desulfurized in an undivided batch cell. The effects of proton donor, supporting electrolyte, coal content, potential and temperature on desulfurization conversion were investigated. The optimum conditions were as follows: CzH50H:HzO = 1.8:1 (volume), BuaNBr = 0.25 molil, coal = 0.045 g/ml, E = -2.5 V (vs. SCE), and T = 310 K. During desulfurization, mild hydrogenation was observed. Enzymic depolymeriration of low-rank coal (lignite) 98100062 Hofrichter, M. et al. DGMK Tagungsber., 1997, 9704. (Proceedings ICCS ‘97, Volume 3), 1595-1598. Ligninolytic basidiomycetes can degrade low-rank coal (lignite). Extracellular Mn peroxidase (MOP) is the decisive enzyme in the depolymerization process both of coal-derived humic substances and native coal. The depolymerization of coal occurred via Mn”+ ions acting as primary mediator and can be considerably enhanced by certain thiols acting as secondary mediators. The depolymerization process leads finally to complex mixtures of fulvic acid-like compounds.