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Effect of metal-containing additives on NOx reduction in combustion and reburning
04 By-products related to fuels between the bimodal gamma pore size distribution and DFT-cumregularization based pore size distribution is also observed, supporting the validity of the proposed model.
02/01435 Chemical and physical activation of olive-mill waste water to produce activated carbons Moreno-Castilla, C. et al. Carbon, 2001, 39, (9), 1415-1420. Olive-mill waste water is produced in large quantities during the manufacture process of the olive oil in mills. This by-product has been used as raw material to produce activated carbons by both chemical and physical activation methods. In the first case, KOH and H3PO4 w e r e used as activating agent, and in the second ease, CO2 at 840°C for different periods of time. Results obtained indicate that the chemical activation with KOH at 800°C, in an inert atmosphere, yielded activated carbons with the highest surface area and more developed micro, meso and macroporosity.
02/01436 Comparative studies of petroleum residues and coal tar by air blowing Zhang, H. et aL Meitan Zhuanhua, 2001, 24, (3), 79-82. (In Chinese) Coal tar pitch and petroleum pitch were prepared from petroleum residues and coal tar by air blowing respectively. Raw material and modified pitches were characterized by 1H-NMR, 13C-NMR, softening point, elemental analysis, solubility, and polarized microscope. T h e study of the pitches showed that the air blowing effectively increases softening point, insoluble contents, coke yield through dehydrogenating polymerization. Both series of pitches were carbonized at 480 = under 1.6 MPa. The optical texture of coke obtained from coal tar pitches varied according to the oxidation condition. But the optical texture of coke obtained from petroleum pitches all showed small domains.
02/01437 Ecological issues in storing and treatment of mineral fraction from solid fuels at thermal power plants Madoyan, A.A. Ekol. Prom. Proizvod., 2001, 2, 44-46. (In Russian) Disposal of coal-burning power plant ashes is discussed. Recultivation of landfills with grasses and shrubs is considered.
02/01438 Effect of metal-containing additives on NOx reduction in combustion and reburning Lissianski, V.V. et al. Combust. Flame, 2001, 125, (3), 1118-1127. This paper describes experimental and modelling studies on the effect of metal-containing compounds on NOx reduction. Sodium and potassium carbonates, calcium acetate, and fly ash were injected into a 300 kW combustor in one of the following configurations: with the main fuel, with the reburning fuel, or into the reburning zone. Natural gas was used as the main fuel and the reburning fuel. Tests showed that co-injection of Na-, K-, and Ca- containing compounds with the main fuel reduced NOx emissions with and without reburning. Co-injection of Na-, K-, and Ca-containing additives along with the reburning fuel and into the reburning zone downstream of the reburning fuel had a smaller effect than co-injection with the main fuel. Fly ash showed a minimal effect on NOx reduction. A potential benefit of using calciumcontaining additives in reburning is reduced SO2 emissions during coal combustion. About 50% SO2 reduction was achieved with injection of 1000 ppm of Ca(OH)2 with the main fuel. Modelling was used to determine the mechanism of the effect of Na-containing additives on NOx reduction. The model combined a detailed description of the reburning chemical with a simplified representation of mixing. Modelling suggested that reduction of NOx emissions in the presence of sodium-containing compounds was due to the inhibition of the combustion process by sodium. Because NOx formation via thermal and fuel-NO mechanisms strongly depends on the local combustion environment, NOx formation in the main combustion zone was inhibited because H, OH, and O concentrations in the combustion zone decreased in the presence of Na. The increase in NOx reduction in the reburning zone was due to slower oxidation of the reburning fuel in the presence of Na.
02/01439 Effect of the composition and properties of raw materials on the yield of solid product in thermolysis of coal with a low degree of metamorphism Shui'ga, I.V. Koks Khim., 2001, 7, 6-9. (In Russian) Experimental and modelling studies of thermoiysis of low rank coals w e r e carried out, indicating different mechanisms of formation of solid combustibles. The solid combustibles obtained from brown coals w e r e formed by thermal decomposition of coal organic matter. An increase in the mineral matter content of coal results in separation of active sites of organic matter which decreases the yield of the solid combustibles. In the thermolysis of somewhat caking long flame coals, the yield of the solid combustibles depended on the decomposition and, to some d e g r e e , on polycondensation processes. Increase in the thickness of the plastic layer and the amount of formed liquid substances led to intensification of the polycondensation, increasing the yield of the combustible mass of the solid product.
02/01440 Electrochemical properties of PAN-based carbon fibers as anodes for rechargesble lithium ion batteries Lee, J.K. et al. Carbon, 2001, 39, (9), 1299-1305. Polyacryionitrile(PAN)-based carbon fibres were tested as anodes for lithium ion rechargeabie batteries. PAN-based fibres were first stabilized under tension in air at about 200°C (stabilization tension) and then carbonized in different gas environments (carbonization atmospheres) at heat treatment temperatures (HTT) between 700 and 1500°C. The carbon fibre electrodes were prepared at various conditions using the stabilized PAN fibres and then their electrochemical characteristics were investigated. The PAN-based carbon fibre prepared at an oxidative stabilization tension of ca. 10 MPa showed the highest discharge capacity in our experimental range. We found that the effective diffusion coefficient of lithium in the carbon fibre electrode was influenced by the carbonization environment employed. The electrochemical intercalation process depended on mass transfer of lithium into carbon layer which is rate-determining during the electrode charge-discharge process. The effect of HTT on discharge capacity varied depending on the combined effect of both the amount of intercalation sites available and the electric conductivity of the carbon fibre used.
02/01441 Evolution characteristics of gases during pyrolysis of mecerel concentrates of Russian coklng coals Das, T.K. Fuel, 2001, 80, (4), 489-500. The major constituents that control the properties of coking coals are vitrinite and fusinite. Thus, for better understanding of the thermochemical reactions during the carbonization of coking coals, the evolution characteristics of gaseous products during pyrolysis were studied with four samples of vitrinite-richand four samples of fusiniterich concentrates of Russian coking coals of rank (Ro) varying from 0.80 to 1.54. Maceral concentrates were generated by repeated cycles of float-sink separation under centrifugal force. The gases evolved during themogravimetric analysis of the maceral concentrates were analysed by gas chromatography for the content of methane, hydrogen, carbon dioxide and carbon monoxide. The major constituents of gaseous products were methane, carbon monoxide and hydrogen. The amount of carbon dioxide evolved was observed to be insignificantcompared to the amounts of hydrogen, methane and carbon monoxide. Graphs were plotted between the rates of evolution of the above gaseous components and temperature for different macerai concentrates to study their evolution characteristics. A clear difference in yields of methane, carbon monoxide and hydrogen in vitrinite-and fusinite-rich concentrates could be observed from the study. Content of hydrogen, methane and carbon monoxide varied from 55 to 65, 29 to 37 and 6 to 12%, respectively,in vitrinite-richconcentrates and from 57 to 70, 19 to 22 and 11 to 22%, respectively, in fusinite-rich concentrates. The evolution behaviour of gaseous products during primary devolatilization (260-550°C) and secondary devoiatiiization(550--850°C) was also discussed. Mathematical analysis was carried out to identify the significant factors and regression equations for prediction of the yield and composition of the gaseous products. Some of the most distinguishing features of this study are: (a) use of a broad range of coking coals; (b) study of the gas evolution pattern for bothI vitriniteand fusinite-richconcentrates at a heating rate of 5°C min- . which is very close to the standard carbonization practice of 3°C min-I, and the temperature range of heating was from room temperature to 900°C, which is close to the high-temperature carbonization of I000°C, and (d) the study of the gas evolution behaviour during primary and secondary devolatilization.
02/01442 Formation and use of coal combustion residues from three types of power plants burning Illinois coals Demir, I. et al. Fuel, 2001, 80, (11), 1659-1673. Coal, ash, and limestone samples from a fluidized bed combustion (FBC) plant, a pulverized coal combustion (PC) plant, and a cyclone (CYC) plant in Illinois were analysed to determine the combustion behaviour of mineral matter, and to propose beneficial uses for the power plant ashes. Pyrite and marcasite in coal were converted during combustion to glass, hematite and magnetite. Calcite was converted to lime and anhydrite. The clay minerals were altered to muliite and glass. Quartz was partially altered to glass. Trace elements in coal w e r e partially mobilized during combustion and, as a result, emitted into the atmosphere or adsorbed on fly ash or on hardware on the cool side of the power plants. Overall, the mobilities of 15 trace elements investigated were lower at the FBC plant than at the other plants. Only F and Mn at the FBC plant, F, Hg, and Se at the PC plant and Be, F, Hg, and Se at the CYC plant had over 50% of their concentrations mobilized. Se and Ge could be commercially recovered from some of the combustion ashes. The FBC ashes could be used as acid neutralizing agents in agriculture and waste treatment, and to produce sulfate fertilizers, gypsum wall boards, concrete, and cement. The PC and CYC fly ashes can potentially be used in the production of cement,
Fuel end Energy Abstracts May 2002 185
02/01435 Chemical and physical activation of olive-mill waste water to produce activated carbons Moreno-Castilla, C. et al. Carbon, 2001, 39, (9), 1415-1420. Olive-mill waste water is produced in large quantities during the manufacture process of the olive oil in mills. This by-product has been used as raw material to produce activated carbons by both chemical and physical activation methods. In the first case, KOH and H3PO4 w e r e used as activating agent, and in the second ease, CO2 at 840°C for different periods of time. Results obtained indicate that the chemical activation with KOH at 800°C, in an inert atmosphere, yielded activated carbons with the highest surface area and more developed micro, meso and macroporosity.
02/01436 Comparative studies of petroleum residues and coal tar by air blowing Zhang, H. et aL Meitan Zhuanhua, 2001, 24, (3), 79-82. (In Chinese) Coal tar pitch and petroleum pitch were prepared from petroleum residues and coal tar by air blowing respectively. Raw material and modified pitches were characterized by 1H-NMR, 13C-NMR, softening point, elemental analysis, solubility, and polarized microscope. T h e study of the pitches showed that the air blowing effectively increases softening point, insoluble contents, coke yield through dehydrogenating polymerization. Both series of pitches were carbonized at 480 = under 1.6 MPa. The optical texture of coke obtained from coal tar pitches varied according to the oxidation condition. But the optical texture of coke obtained from petroleum pitches all showed small domains.
02/01437 Ecological issues in storing and treatment of mineral fraction from solid fuels at thermal power plants Madoyan, A.A. Ekol. Prom. Proizvod., 2001, 2, 44-46. (In Russian) Disposal of coal-burning power plant ashes is discussed. Recultivation of landfills with grasses and shrubs is considered.
02/01438 Effect of metal-containing additives on NOx reduction in combustion and reburning Lissianski, V.V. et al. Combust. Flame, 2001, 125, (3), 1118-1127. This paper describes experimental and modelling studies on the effect of metal-containing compounds on NOx reduction. Sodium and potassium carbonates, calcium acetate, and fly ash were injected into a 300 kW combustor in one of the following configurations: with the main fuel, with the reburning fuel, or into the reburning zone. Natural gas was used as the main fuel and the reburning fuel. Tests showed that co-injection of Na-, K-, and Ca- containing compounds with the main fuel reduced NOx emissions with and without reburning. Co-injection of Na-, K-, and Ca-containing additives along with the reburning fuel and into the reburning zone downstream of the reburning fuel had a smaller effect than co-injection with the main fuel. Fly ash showed a minimal effect on NOx reduction. A potential benefit of using calciumcontaining additives in reburning is reduced SO2 emissions during coal combustion. About 50% SO2 reduction was achieved with injection of 1000 ppm of Ca(OH)2 with the main fuel. Modelling was used to determine the mechanism of the effect of Na-containing additives on NOx reduction. The model combined a detailed description of the reburning chemical with a simplified representation of mixing. Modelling suggested that reduction of NOx emissions in the presence of sodium-containing compounds was due to the inhibition of the combustion process by sodium. Because NOx formation via thermal and fuel-NO mechanisms strongly depends on the local combustion environment, NOx formation in the main combustion zone was inhibited because H, OH, and O concentrations in the combustion zone decreased in the presence of Na. The increase in NOx reduction in the reburning zone was due to slower oxidation of the reburning fuel in the presence of Na.
02/01439 Effect of the composition and properties of raw materials on the yield of solid product in thermolysis of coal with a low degree of metamorphism Shui'ga, I.V. Koks Khim., 2001, 7, 6-9. (In Russian) Experimental and modelling studies of thermoiysis of low rank coals w e r e carried out, indicating different mechanisms of formation of solid combustibles. The solid combustibles obtained from brown coals w e r e formed by thermal decomposition of coal organic matter. An increase in the mineral matter content of coal results in separation of active sites of organic matter which decreases the yield of the solid combustibles. In the thermolysis of somewhat caking long flame coals, the yield of the solid combustibles depended on the decomposition and, to some d e g r e e , on polycondensation processes. Increase in the thickness of the plastic layer and the amount of formed liquid substances led to intensification of the polycondensation, increasing the yield of the combustible mass of the solid product.
02/01440 Electrochemical properties of PAN-based carbon fibers as anodes for rechargesble lithium ion batteries Lee, J.K. et al. Carbon, 2001, 39, (9), 1299-1305. Polyacryionitrile(PAN)-based carbon fibres were tested as anodes for lithium ion rechargeabie batteries. PAN-based fibres were first stabilized under tension in air at about 200°C (stabilization tension) and then carbonized in different gas environments (carbonization atmospheres) at heat treatment temperatures (HTT) between 700 and 1500°C. The carbon fibre electrodes were prepared at various conditions using the stabilized PAN fibres and then their electrochemical characteristics were investigated. The PAN-based carbon fibre prepared at an oxidative stabilization tension of ca. 10 MPa showed the highest discharge capacity in our experimental range. We found that the effective diffusion coefficient of lithium in the carbon fibre electrode was influenced by the carbonization environment employed. The electrochemical intercalation process depended on mass transfer of lithium into carbon layer which is rate-determining during the electrode charge-discharge process. The effect of HTT on discharge capacity varied depending on the combined effect of both the amount of intercalation sites available and the electric conductivity of the carbon fibre used.
02/01441 Evolution characteristics of gases during pyrolysis of mecerel concentrates of Russian coklng coals Das, T.K. Fuel, 2001, 80, (4), 489-500. The major constituents that control the properties of coking coals are vitrinite and fusinite. Thus, for better understanding of the thermochemical reactions during the carbonization of coking coals, the evolution characteristics of gaseous products during pyrolysis were studied with four samples of vitrinite-richand four samples of fusiniterich concentrates of Russian coking coals of rank (Ro) varying from 0.80 to 1.54. Maceral concentrates were generated by repeated cycles of float-sink separation under centrifugal force. The gases evolved during themogravimetric analysis of the maceral concentrates were analysed by gas chromatography for the content of methane, hydrogen, carbon dioxide and carbon monoxide. The major constituents of gaseous products were methane, carbon monoxide and hydrogen. The amount of carbon dioxide evolved was observed to be insignificantcompared to the amounts of hydrogen, methane and carbon monoxide. Graphs were plotted between the rates of evolution of the above gaseous components and temperature for different macerai concentrates to study their evolution characteristics. A clear difference in yields of methane, carbon monoxide and hydrogen in vitrinite-and fusinite-rich concentrates could be observed from the study. Content of hydrogen, methane and carbon monoxide varied from 55 to 65, 29 to 37 and 6 to 12%, respectively,in vitrinite-richconcentrates and from 57 to 70, 19 to 22 and 11 to 22%, respectively, in fusinite-rich concentrates. The evolution behaviour of gaseous products during primary devolatilization (260-550°C) and secondary devoiatiiization(550--850°C) was also discussed. Mathematical analysis was carried out to identify the significant factors and regression equations for prediction of the yield and composition of the gaseous products. Some of the most distinguishing features of this study are: (a) use of a broad range of coking coals; (b) study of the gas evolution pattern for bothI vitriniteand fusinite-richconcentrates at a heating rate of 5°C min- . which is very close to the standard carbonization practice of 3°C min-I, and the temperature range of heating was from room temperature to 900°C, which is close to the high-temperature carbonization of I000°C, and (d) the study of the gas evolution behaviour during primary and secondary devolatilization.
02/01442 Formation and use of coal combustion residues from three types of power plants burning Illinois coals Demir, I. et al. Fuel, 2001, 80, (11), 1659-1673. Coal, ash, and limestone samples from a fluidized bed combustion (FBC) plant, a pulverized coal combustion (PC) plant, and a cyclone (CYC) plant in Illinois were analysed to determine the combustion behaviour of mineral matter, and to propose beneficial uses for the power plant ashes. Pyrite and marcasite in coal were converted during combustion to glass, hematite and magnetite. Calcite was converted to lime and anhydrite. The clay minerals were altered to muliite and glass. Quartz was partially altered to glass. Trace elements in coal w e r e partially mobilized during combustion and, as a result, emitted into the atmosphere or adsorbed on fly ash or on hardware on the cool side of the power plants. Overall, the mobilities of 15 trace elements investigated were lower at the FBC plant than at the other plants. Only F and Mn at the FBC plant, F, Hg, and Se at the PC plant and Be, F, Hg, and Se at the CYC plant had over 50% of their concentrations mobilized. Se and Ge could be commercially recovered from some of the combustion ashes. The FBC ashes could be used as acid neutralizing agents in agriculture and waste treatment, and to produce sulfate fertilizers, gypsum wall boards, concrete, and cement. The PC and CYC fly ashes can potentially be used in the production of cement,
Fuel end Energy Abstracts May 2002 185