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00522 Characterization multicomponent fuel effects during the initial stages of pulverized coal combustion
09
Combustion
(burners, combustion systems)
98/00510 Vortex combustion of solid fuel in boilers with horizontal and vertical cyclone forechambers Korchevoi, Y. P. &erg. Elekrrif 1997, (2). 7-10. (In Russian) Coals containing 35 wt% ash and 10-40 wt% volatiles can be burned in boilers with horizontal and vertical cyclone forechambers with minimum demand for supplemental fuel. Anthracite containing 4-9 wt% volatiles can be burned in these boilers without supplemental fuel.
09
COMBUSTION Burners,
Combustion
Systems
Activation energy for the oxidation of Malaysian 9810051i coal chars Haji-Sulaiman, M. Z. and Aroua, M. K. .I. Insr. Energy. 1997, 70, (483), 5256. Thermal gravimetric analysis was used to study the oxidation of two Malaysian coal chars. The Temperature Program Reaction technique, which employed the random pore model of Bhatia & Perlmutter, was used to analyse the weight-loss data. All experiments were conducted within a temperature range of 698-773 K and heating rates of 2-10 K min-’ with char samples in the size range 53-75 ,Lm. The random pore model can accurately describe the oxidation of char to yield activation energy. It is similar to that obtained from model free kinetics, provided the structural parameter ~1, which is an input to the model, is taken as an adjustable parameter.
98100512 Alkali release and adsorption by ash components and additives during the combustion of lignites Muchmore, C. B. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 1047-1050. Sodium and potassium release from lignite was studied in laboratory-scale combustion and gasification experiments. When 50% sewage sludge was added to the lignite, the alkali release decreased significantly, while kaolin addition showed no positive effect. At higher temperatures the alkali release was lower, indicating the enhanced reaction rate between the alkali metals and the ash compounds. 98100513
Analysis of combustion properties of mixed coal Qiu, S. et al. Shandong Jiancai Xueyuan Xuebao, 1997, 11, (1) 27-31, 36. (In Chinese) A study of three different kinds of coal and their blends in varying proportions used in the cement industry was performed by TGA. The combustion characteristics of these coal blends and their effects on clinkering are investigated.
98100514
Analysis of combustion properties of mixed coal Qiu, S. et al. Shandong Jiancai Xueyuon Xuebao, 1997, 11, (l), 27-31, 36. (In Chinese) TGA was used to analyse three different kinds of coal and their blends in different proportions used in the cement industry. The combustion characteristics of these coal blends and their effects on clinkering were investigated. Assessing coal quality impacts on PC [personal 9aioo5i 5 computer] combustion behaviour Niksa, S. DGMK Tugungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 947-950. A computational approach based on FLASHCHAIN for assessing coal quality impacts that achieves the accuracy of laboratory testing for a fraction of the expense is introduced. Two applications are considered here. First, the model is used to identify the parameter values in the simple devolatilization rate expressions used in coal combustor simulators that mimic the FLASHCHAIN predictions. In the second application, predicted yields for rapid heating conditions and coal-nitrogen release are used as regression variables in engineering correlations to relate coal quality to NO, emissions and unburned carbon in ash from full-scale furnaces. Carbons as models for coal devolatilization and 9aioo516 combustion DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Jones, .I. M. et al. Volume 2), 1083-1086. Coal-fuelled power generation experiences problems from fuel-NO, emissions. Consequently, the fate of fuel-nitrogen during combustion is a topic of great interest and an understanding of how the different forms of nitrogen in coal are released during devolatilization and combustion is one approach towards predicting NO, emissions. Nitrogen-containing carbons were used as models to study NO, release during coal combustion. The
44
Fuel and Energy Abstracts
January 1999
presence of impregnated catalytic metals and chelated metal species were investigated in an attempt to examine the role of trace metals on nitrogen release during pyrolysis and combustion.
98100517 Catalytic influence of ash elements on NO, formation from bound nitrogen in coal combustion Kopsel, R. and Halang, S. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 1119-l 122. NO, formation/reduction reactions are mainly catalytic. For the purpose of investigating the influence of coal ash comparative experiments were carried out with original, deashed. and impregnated lignite and hard coal. Further insight into the catalytic activity of ash components was obtained by experiments with selected gas mixtures over different bed materials in a quartz glass tube reactor. Conclusions were drawn on the proceeding reactions and the catalytic activity of the individual ash components. Many single ash components like CeO, MgO, and Fe203 are also effective as catalysts. CaS04 is largely inert iron oxide has the highest activity for NO reduction as well as NH-, oxidation to NO. 9810051a Characteristics of char combustion in a high temperature advanced furnace for the high performance power system Cho, S. M. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 233244.
Foster Wheeler Development Corporation, under the sponsorship of the United States Department of Energy-Pittsburgh Energy Technology Center, is developing a high performance power system (HIPPS) with a thermal-to-electricity conversion efficiency of more than 47%. This system is a coal-fired combined cycle system that employs a high temperature advanced furnace (HITAF) to transfer the heat to the air and steam working fluids. In the HIPPS plant, pulverized coal and sorbent are fed into the pyrolyzer where the coal is partially gasified to produce a low-Btu fuel gas and combustible char. The fuel gas is supplied to the gas turbine combustor and the char is burned in the HITAF. This paper examines char combustion in the HITAF. It presents laboratory characterization of char combustion and numerical simulation of char combustion in a subscale test combustor. The laboratory characterization tests are conducted to determine the char ignition index, relative fuel reactivity. and drop-tube furnace performance. Numerical simulation of char combustion at the Foster Wheeler CETF is performed using a state-of-the-art furnace combustion computational fluid dynamics (CFD) code. The results of the laboratory bench-scale tests to characterize the char and CFD simulation of a sub-scale test combustor are detailed in the paper. Characteristics of pulverized coal combustion with 9aioo5i 9 complex swirl jets. (1). Experiment CU. F. and Xu. J. Ranshao Kexue Yu Jiuhu, 1997, 3. (2). 190-196. (In Chinese) An experimental study into the characteristics of pulverized coal comhustion with complex swirl jets is reported. The tests used three types of coal (brown coal, bituminous coal and anthracite) and various concentrations of coal particles in the jets. The temperature distribution, several gaseous components’ distributions, heat radiation distribution and coal particle characterizations were measured. The effect of the type of coal and the concentration of coal particles in the jets on the combustion behaviours are discussed. The results show the advantages of the combustion and the study determined the properties of the combustor.
9aioo520 Characteristics of pulverized coal combustion with complex swirl jets. (2). Numerical simulation Cu, F. and Xu, J. Ranshao Kexue Yu Jishu, 1997. 3, (2), 197-205. (In Chinese) The numerical calculation of pulverized coal combustion with complex swirl jets is described. The computing process consists of several parts, including fluid turbulent flow, turbulent gaseous chemical reactions, gas-solid twophase flow, complex coal particle combustion, and flame radiation. Some advanced models and theories were applied in the simulations. The distributions of the temperature, gaseous components and concentration of particle and particle track, flame surface were computed. The results and the experiment agreed well and thus the combustion characteristics were derived. 9aioo52i
Characteristics of underground coal combustion Troshen’kin. B. A. and Markosova. V. P. Ugol’ Ukr., 1996, (2) 6-7. (In Russian) At1300 K it is controlled by diffusion. Correlations are given for gas velocity in air injection and production wells and Nusselt number under underground combustion conditions.
98100522
Characterization multicomponent fuel effects during the initial stages of pulverized coal combustion ICCS Niksa, S. and Cho, S. DGMK Tagungsber.. 1997, 9703, (Proceedings ‘97, Volume 2), 1147-1150. The paper reports the complete distributions of all major products for the oxidative pyrolysis and combustion of premixed suspensions of suhbituminous, Pit. #8 hvA bituminous, and low volatile bituminous coals after 150 ms in a one-dimensional coal flame. As inlet O2 levels were progressively increased from 0 to 15% in successive tests, the process
09
chemical moved through oxidative volatiies pyrolysis, volatiles combustion, soot combustion, and char oxidation. However, only with the low volatility coal were the different fuel components consumed sequentially. Char, soot, and non-condensable fuels burned simultaneously with the sub-bituminous coal and, to a lesser degree, with the Pit. #8. Consequently, hydrocarbon gases from these coals were present while most of the soot and char was converted into gases. Co-combustion of sewage sludge in a lignite-fired 9aloo523 industrial power station Bierbaum, K. et al. Chemical-Ing.-Tech.. 1997, 69, (7), 973-976. (In German) A summary of the operation of a large-scale test about co-combustion of mechanical dehydrated sewage sludge in a circulating fluidized-bed steam generator. A plant concept consisting of steam generator, units for sewage sludge deliverance and flue gas fine cleaning is introduced. The advantages of sewage sludge co-combustion are valued under aspects of energy balance, environmental protection, reduction of costs, and restrictions of recycle and waste orders. Co-pyrolysis of coal with waste materials 98100524 Buchtele, J. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2) 869-872. In a stationary bed, co-pyrolysis of coking coal with waste plastics was performed and the mass balance of the process was evaluated and the products’ properties characterized. Low ash and sulfur content, and a good oxyreactivity was displayed in the fine-grained coke obtained, making it suitable as a smokeless fuel. The tar produced may be used for chemical treatment as well as a low-sulfur heating oil and the gas is suitable as the heating gas for co-coke oven. Coal combustion in oxygen-recirculated flue gas in 90100525 a pressurized fluidized-bed combustor Bonn, B. et al. VDI-Eer., 1997, 1321, 179-191. (In German) The paper describes coal combustion experiments performed by DMT in a pressurized fluidized bed combustor in which dried flue gas was recirculated, and pure oxygen was added for combustion. Coal combustion in recycled flue gas and oxygen mixtures is feasible without problems. Burnout is not significantly changed by replacing Nz with COz. Temperature distribution in the combustor shows lower gradients. Only small amounts of flue gas are formed but with markedly higher concentrations of NO, NzO, SOz, and CO. The conversion rate of N to NO and NlO, of S to SO2 and C to CO is very much reduced compared to conventional combustion in air. Pressure and temperature effects on emissions shows similar trends in flue gas recycle as in conventional combustion, although at much reduced level. Coals and their solid pyrolysis products-distribu98100526 tion of ash, volatile matter, and sulfur in grain classes Czaplicki, A. and Smolka, W. Karbo-Energochemical-Ekol., 1997, 42, (8), 269-272. (In Polish) In a reactor with a circulating fluidized bed, coals from the Staszic and Myslowice coal mines were pyrolysed under constant temperature-flow conditions. The raw coals and carbonizates were fractionated into 11 grain classes. For each class the contents of ash, volatile matter, total sulfur and density were analysed. Sulfur forms and the chemical composition of ashes as well as the temperature of theirs phase changes were determined for average samples of coals and carbonizates. Combustion and inorganic emissions of ground 98100527 waste tires Levendis, Y. A. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1995, 20, 477-488. The combustion characteristics and emissions of SOz, NO, and CO> gases from ground waste tyres were assessed and results were compared with those obtained from burning pulverized coal. Laboratory bench-scale experiments were conducted in a drop-tube, laminar-flow furnace, in air at fuel-lean conditions, at gas temperatures ranging from 1300 K to 1600 K. Two particle size cuts were burned from both materials, 75-90 pm and 180212 ,Irn. Blends of coal and tyre particles, at equal weight ratios, were also burned. The experimental results are presented fully in the paper. Combustion behavior of coal-waste flames in 98100528 pulverized fuel firing systems. Inflame-measurements in a pilot scale facility with hard coal and dried sewage sludge Gerhardt, T. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22nd, 389-400. During combustion of coal mixtures with O-48 wt% sewage sludge, nitrogen oxide, carbon monoxide, oxygen and temperature profiles were measured in flames in a pilot plant at coal and sludge throughput O-25.3 and 27.3-36.4 kg/h, respectively. Combustion calorimetric and thermogravimetric 98100529 studies of graphite and coals doped with a coal-burning additive Zhang, L.-M. et al. Thermochim. Acta, 1997, 299, (l-2). 13-17. The paper studies the effect of an additive (composed mainly of Mg, Fe, Mn, Al, Si and boron oxides) on coal combustion and graphite oxidation.
Combustion
(burners, combustion
systems)
90lOO530 Combustion characteristics of intensively cleaned coal fractions. Effect of mineral matter Rubiera, F. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 1003-1006. The influence of intensive coal cleaning on the combustion behaviour of density-separated coal fractions was studied. Samples with ash contents varying from 39% for the raw coal, to 2% for the cleanest fraction were obtained and temperature-programmed combustion and isothermal gasification in air were used to measure the reactivities of the parent coal and the cleaned fractions. Coal and char reactivities increased with increasing ash content of the samples. Thermal analysis-mass spectrometry of the lowtemperature ashes was used to study the reactions of coal minerals under combustion conditions. Combustion of fluidized-bed coal and clarifier 98100531 sludge in the LCS cycloidal furnace Schrader, A. et al. VDI-Ber., 1997, 1313, (Verbrennung und Feuerungen), 169-176. (In German) LCS-type cyclone furnaces were developed by the L. & C. Steinmueller Corporation (GmbH) for low-emission combustion of low-Btu fuels and combustible wastes. The design, firing experiences, and furnace operations are described. Combustion is characterized by a high degree of burnout, completeness of combustion, and long residence time. These furnaces are especially useful in the combustion of spent activated carbon sorbents from flue gas purification, waste coke, dried pulverized brown coal, clarifier sludge, and biomass. 98100532 Combustion reactivity of chars from copyrolysis of coal with coke-oven gas Liao, H. Q. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2) 1015-1018. The pyrolysis pressure and heating rate relates to the combustion reactivity of char from pyrolysis of Xianfeng lignite with coke-oven gas (COG). Char yields and combustion reactivity are enhanced by decreasing pressure and increasing heating rate. The combustion reactivities of char from coal pyrolysis with COG nearly reach that of char from hydropyrolysis, but are lower than those of char from coal pyrolysis under N: 9aioo533 Comparison of different mechanisms for the product formation in the simulation of coal pyrolysis Petek, J. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 557-560. Different models for coal pyrolysis were studied over a wide range of operational conditions using a computer program for the simulation of the pyrolysis of solid fuels. Two models for tar formation are presented and compared to the results of experiments with thermobalances, a wire mesh apparatus, and a drop tube reactor. Good results were obtained for the simulation of the pyrolysis of large particles with a simple correlation of the tar yield with the heating rate. However, a more complex reaction scheme is required to describe the product formation at very high heating rates, since the reaction rate of the thermal break-up of the coal macromolecules becomes rate-determining. 98100534 Composition and morphology of fly ash from fluidized-bed combustion of brown coal Sykorova, I. et al. DGMK Tagungsber., 1997, 9703, 1187-l 190. The study determines the chemical composition and morphology of fly ash captured in cyclone, bottom ash, and ultrafine particles separated in the low pressure impactor produced by the two modes of combustion are determined The two type of brown coal from the North Bohemian basin is characterized by reflectance, maceral, mineralogical, and chemical composition Composition and morphology of fly ash depends on reaction conditions, coal quality, and size distribution of particles. 98loo535 Conversion of char nitrogen to N2 under incomplete combustion conditions Zhuang, Q.-L. et al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1996, 33, 237-240. (In Japanese) A batch scale quartz-made fluidized bed reactor was employed to study the combustion of a char prepared from a Chinese lignite at 1123 K to confirm the parameters affecting the conversion of char-N to N:. Almost all of the N-containing gases during combustion was NZ under 02-lean conditions, and only small amounts of NH7 and HCN. However, no NO, and NzO were detected. The formation of Nz took place in the final stage of combustion, pyridinic-N disappeared completely and pyrrolic-N decreased, while Ocontaining nitrogen complexes became the main component. A mechanism for conversion reactions of char-N in combustion was discussed. 98100536 Dependence of single coal particle ignition mechanism on the surrounding volatile matter cloud Katalambula, H. et al. Energy Fuels, 1997, 11, (5), 1033-1039. Experiments were conducted to study the effect of volatile matter cloud surrounding a single coal particle on the ignition mechanism. Three different experimental conditions that had different convection intensities were used: microgravity with negligible convection, normal gravity with natural convection, and normal gravity with forced convection. Three types of coal with mean particle sizes of 0.8, 1.0, and 1.2 mm were ignited in air by heat radiation at heating rates of 770-900 K/s. Results showed that the amount of volatiles remaining in the vicinity of the particle is significantly
Fuel and Energy Abstracts
January 1998
45
Combustion
(burners, combustion systems)
98/00510 Vortex combustion of solid fuel in boilers with horizontal and vertical cyclone forechambers Korchevoi, Y. P. &erg. Elekrrif 1997, (2). 7-10. (In Russian) Coals containing 35 wt% ash and 10-40 wt% volatiles can be burned in boilers with horizontal and vertical cyclone forechambers with minimum demand for supplemental fuel. Anthracite containing 4-9 wt% volatiles can be burned in these boilers without supplemental fuel.
09
COMBUSTION Burners,
Combustion
Systems
Activation energy for the oxidation of Malaysian 9810051i coal chars Haji-Sulaiman, M. Z. and Aroua, M. K. .I. Insr. Energy. 1997, 70, (483), 5256. Thermal gravimetric analysis was used to study the oxidation of two Malaysian coal chars. The Temperature Program Reaction technique, which employed the random pore model of Bhatia & Perlmutter, was used to analyse the weight-loss data. All experiments were conducted within a temperature range of 698-773 K and heating rates of 2-10 K min-’ with char samples in the size range 53-75 ,Lm. The random pore model can accurately describe the oxidation of char to yield activation energy. It is similar to that obtained from model free kinetics, provided the structural parameter ~1, which is an input to the model, is taken as an adjustable parameter.
98100512 Alkali release and adsorption by ash components and additives during the combustion of lignites Muchmore, C. B. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 1047-1050. Sodium and potassium release from lignite was studied in laboratory-scale combustion and gasification experiments. When 50% sewage sludge was added to the lignite, the alkali release decreased significantly, while kaolin addition showed no positive effect. At higher temperatures the alkali release was lower, indicating the enhanced reaction rate between the alkali metals and the ash compounds. 98100513
Analysis of combustion properties of mixed coal Qiu, S. et al. Shandong Jiancai Xueyuan Xuebao, 1997, 11, (1) 27-31, 36. (In Chinese) A study of three different kinds of coal and their blends in varying proportions used in the cement industry was performed by TGA. The combustion characteristics of these coal blends and their effects on clinkering are investigated.
98100514
Analysis of combustion properties of mixed coal Qiu, S. et al. Shandong Jiancai Xueyuon Xuebao, 1997, 11, (l), 27-31, 36. (In Chinese) TGA was used to analyse three different kinds of coal and their blends in different proportions used in the cement industry. The combustion characteristics of these coal blends and their effects on clinkering were investigated. Assessing coal quality impacts on PC [personal 9aioo5i 5 computer] combustion behaviour Niksa, S. DGMK Tugungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 947-950. A computational approach based on FLASHCHAIN for assessing coal quality impacts that achieves the accuracy of laboratory testing for a fraction of the expense is introduced. Two applications are considered here. First, the model is used to identify the parameter values in the simple devolatilization rate expressions used in coal combustor simulators that mimic the FLASHCHAIN predictions. In the second application, predicted yields for rapid heating conditions and coal-nitrogen release are used as regression variables in engineering correlations to relate coal quality to NO, emissions and unburned carbon in ash from full-scale furnaces. Carbons as models for coal devolatilization and 9aioo516 combustion DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Jones, .I. M. et al. Volume 2), 1083-1086. Coal-fuelled power generation experiences problems from fuel-NO, emissions. Consequently, the fate of fuel-nitrogen during combustion is a topic of great interest and an understanding of how the different forms of nitrogen in coal are released during devolatilization and combustion is one approach towards predicting NO, emissions. Nitrogen-containing carbons were used as models to study NO, release during coal combustion. The
44
Fuel and Energy Abstracts
January 1999
presence of impregnated catalytic metals and chelated metal species were investigated in an attempt to examine the role of trace metals on nitrogen release during pyrolysis and combustion.
98100517 Catalytic influence of ash elements on NO, formation from bound nitrogen in coal combustion Kopsel, R. and Halang, S. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 1119-l 122. NO, formation/reduction reactions are mainly catalytic. For the purpose of investigating the influence of coal ash comparative experiments were carried out with original, deashed. and impregnated lignite and hard coal. Further insight into the catalytic activity of ash components was obtained by experiments with selected gas mixtures over different bed materials in a quartz glass tube reactor. Conclusions were drawn on the proceeding reactions and the catalytic activity of the individual ash components. Many single ash components like CeO, MgO, and Fe203 are also effective as catalysts. CaS04 is largely inert iron oxide has the highest activity for NO reduction as well as NH-, oxidation to NO. 9810051a Characteristics of char combustion in a high temperature advanced furnace for the high performance power system Cho, S. M. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 233244.
Foster Wheeler Development Corporation, under the sponsorship of the United States Department of Energy-Pittsburgh Energy Technology Center, is developing a high performance power system (HIPPS) with a thermal-to-electricity conversion efficiency of more than 47%. This system is a coal-fired combined cycle system that employs a high temperature advanced furnace (HITAF) to transfer the heat to the air and steam working fluids. In the HIPPS plant, pulverized coal and sorbent are fed into the pyrolyzer where the coal is partially gasified to produce a low-Btu fuel gas and combustible char. The fuel gas is supplied to the gas turbine combustor and the char is burned in the HITAF. This paper examines char combustion in the HITAF. It presents laboratory characterization of char combustion and numerical simulation of char combustion in a subscale test combustor. The laboratory characterization tests are conducted to determine the char ignition index, relative fuel reactivity. and drop-tube furnace performance. Numerical simulation of char combustion at the Foster Wheeler CETF is performed using a state-of-the-art furnace combustion computational fluid dynamics (CFD) code. The results of the laboratory bench-scale tests to characterize the char and CFD simulation of a sub-scale test combustor are detailed in the paper. Characteristics of pulverized coal combustion with 9aioo5i 9 complex swirl jets. (1). Experiment CU. F. and Xu. J. Ranshao Kexue Yu Jiuhu, 1997, 3. (2). 190-196. (In Chinese) An experimental study into the characteristics of pulverized coal comhustion with complex swirl jets is reported. The tests used three types of coal (brown coal, bituminous coal and anthracite) and various concentrations of coal particles in the jets. The temperature distribution, several gaseous components’ distributions, heat radiation distribution and coal particle characterizations were measured. The effect of the type of coal and the concentration of coal particles in the jets on the combustion behaviours are discussed. The results show the advantages of the combustion and the study determined the properties of the combustor.
9aioo520 Characteristics of pulverized coal combustion with complex swirl jets. (2). Numerical simulation Cu, F. and Xu, J. Ranshao Kexue Yu Jishu, 1997. 3, (2), 197-205. (In Chinese) The numerical calculation of pulverized coal combustion with complex swirl jets is described. The computing process consists of several parts, including fluid turbulent flow, turbulent gaseous chemical reactions, gas-solid twophase flow, complex coal particle combustion, and flame radiation. Some advanced models and theories were applied in the simulations. The distributions of the temperature, gaseous components and concentration of particle and particle track, flame surface were computed. The results and the experiment agreed well and thus the combustion characteristics were derived. 9aioo52i
Characteristics of underground coal combustion Troshen’kin. B. A. and Markosova. V. P. Ugol’ Ukr., 1996, (2) 6-7. (In Russian) At
98100522
Characterization multicomponent fuel effects during the initial stages of pulverized coal combustion ICCS Niksa, S. and Cho, S. DGMK Tagungsber.. 1997, 9703, (Proceedings ‘97, Volume 2), 1147-1150. The paper reports the complete distributions of all major products for the oxidative pyrolysis and combustion of premixed suspensions of suhbituminous, Pit. #8 hvA bituminous, and low volatile bituminous coals after 150 ms in a one-dimensional coal flame. As inlet O2 levels were progressively increased from 0 to 15% in successive tests, the process
09
chemical moved through oxidative volatiies pyrolysis, volatiles combustion, soot combustion, and char oxidation. However, only with the low volatility coal were the different fuel components consumed sequentially. Char, soot, and non-condensable fuels burned simultaneously with the sub-bituminous coal and, to a lesser degree, with the Pit. #8. Consequently, hydrocarbon gases from these coals were present while most of the soot and char was converted into gases. Co-combustion of sewage sludge in a lignite-fired 9aloo523 industrial power station Bierbaum, K. et al. Chemical-Ing.-Tech.. 1997, 69, (7), 973-976. (In German) A summary of the operation of a large-scale test about co-combustion of mechanical dehydrated sewage sludge in a circulating fluidized-bed steam generator. A plant concept consisting of steam generator, units for sewage sludge deliverance and flue gas fine cleaning is introduced. The advantages of sewage sludge co-combustion are valued under aspects of energy balance, environmental protection, reduction of costs, and restrictions of recycle and waste orders. Co-pyrolysis of coal with waste materials 98100524 Buchtele, J. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2) 869-872. In a stationary bed, co-pyrolysis of coking coal with waste plastics was performed and the mass balance of the process was evaluated and the products’ properties characterized. Low ash and sulfur content, and a good oxyreactivity was displayed in the fine-grained coke obtained, making it suitable as a smokeless fuel. The tar produced may be used for chemical treatment as well as a low-sulfur heating oil and the gas is suitable as the heating gas for co-coke oven. Coal combustion in oxygen-recirculated flue gas in 90100525 a pressurized fluidized-bed combustor Bonn, B. et al. VDI-Eer., 1997, 1321, 179-191. (In German) The paper describes coal combustion experiments performed by DMT in a pressurized fluidized bed combustor in which dried flue gas was recirculated, and pure oxygen was added for combustion. Coal combustion in recycled flue gas and oxygen mixtures is feasible without problems. Burnout is not significantly changed by replacing Nz with COz. Temperature distribution in the combustor shows lower gradients. Only small amounts of flue gas are formed but with markedly higher concentrations of NO, NzO, SOz, and CO. The conversion rate of N to NO and NlO, of S to SO2 and C to CO is very much reduced compared to conventional combustion in air. Pressure and temperature effects on emissions shows similar trends in flue gas recycle as in conventional combustion, although at much reduced level. Coals and their solid pyrolysis products-distribu98100526 tion of ash, volatile matter, and sulfur in grain classes Czaplicki, A. and Smolka, W. Karbo-Energochemical-Ekol., 1997, 42, (8), 269-272. (In Polish) In a reactor with a circulating fluidized bed, coals from the Staszic and Myslowice coal mines were pyrolysed under constant temperature-flow conditions. The raw coals and carbonizates were fractionated into 11 grain classes. For each class the contents of ash, volatile matter, total sulfur and density were analysed. Sulfur forms and the chemical composition of ashes as well as the temperature of theirs phase changes were determined for average samples of coals and carbonizates. Combustion and inorganic emissions of ground 98100527 waste tires Levendis, Y. A. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1995, 20, 477-488. The combustion characteristics and emissions of SOz, NO, and CO> gases from ground waste tyres were assessed and results were compared with those obtained from burning pulverized coal. Laboratory bench-scale experiments were conducted in a drop-tube, laminar-flow furnace, in air at fuel-lean conditions, at gas temperatures ranging from 1300 K to 1600 K. Two particle size cuts were burned from both materials, 75-90 pm and 180212 ,Irn. Blends of coal and tyre particles, at equal weight ratios, were also burned. The experimental results are presented fully in the paper. Combustion behavior of coal-waste flames in 98100528 pulverized fuel firing systems. Inflame-measurements in a pilot scale facility with hard coal and dried sewage sludge Gerhardt, T. et al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22nd, 389-400. During combustion of coal mixtures with O-48 wt% sewage sludge, nitrogen oxide, carbon monoxide, oxygen and temperature profiles were measured in flames in a pilot plant at coal and sludge throughput O-25.3 and 27.3-36.4 kg/h, respectively. Combustion calorimetric and thermogravimetric 98100529 studies of graphite and coals doped with a coal-burning additive Zhang, L.-M. et al. Thermochim. Acta, 1997, 299, (l-2). 13-17. The paper studies the effect of an additive (composed mainly of Mg, Fe, Mn, Al, Si and boron oxides) on coal combustion and graphite oxidation.
Combustion
(burners, combustion
systems)
90lOO530 Combustion characteristics of intensively cleaned coal fractions. Effect of mineral matter Rubiera, F. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 1003-1006. The influence of intensive coal cleaning on the combustion behaviour of density-separated coal fractions was studied. Samples with ash contents varying from 39% for the raw coal, to 2% for the cleanest fraction were obtained and temperature-programmed combustion and isothermal gasification in air were used to measure the reactivities of the parent coal and the cleaned fractions. Coal and char reactivities increased with increasing ash content of the samples. Thermal analysis-mass spectrometry of the lowtemperature ashes was used to study the reactions of coal minerals under combustion conditions. Combustion of fluidized-bed coal and clarifier 98100531 sludge in the LCS cycloidal furnace Schrader, A. et al. VDI-Ber., 1997, 1313, (Verbrennung und Feuerungen), 169-176. (In German) LCS-type cyclone furnaces were developed by the L. & C. Steinmueller Corporation (GmbH) for low-emission combustion of low-Btu fuels and combustible wastes. The design, firing experiences, and furnace operations are described. Combustion is characterized by a high degree of burnout, completeness of combustion, and long residence time. These furnaces are especially useful in the combustion of spent activated carbon sorbents from flue gas purification, waste coke, dried pulverized brown coal, clarifier sludge, and biomass. 98100532 Combustion reactivity of chars from copyrolysis of coal with coke-oven gas Liao, H. Q. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2) 1015-1018. The pyrolysis pressure and heating rate relates to the combustion reactivity of char from pyrolysis of Xianfeng lignite with coke-oven gas (COG). Char yields and combustion reactivity are enhanced by decreasing pressure and increasing heating rate. The combustion reactivities of char from coal pyrolysis with COG nearly reach that of char from hydropyrolysis, but are lower than those of char from coal pyrolysis under N: 9aioo533 Comparison of different mechanisms for the product formation in the simulation of coal pyrolysis Petek, J. et al. DGMK Tagungsber., 1997, 9703, (Proceedings ICCS ‘97, Volume 2), 557-560. Different models for coal pyrolysis were studied over a wide range of operational conditions using a computer program for the simulation of the pyrolysis of solid fuels. Two models for tar formation are presented and compared to the results of experiments with thermobalances, a wire mesh apparatus, and a drop tube reactor. Good results were obtained for the simulation of the pyrolysis of large particles with a simple correlation of the tar yield with the heating rate. However, a more complex reaction scheme is required to describe the product formation at very high heating rates, since the reaction rate of the thermal break-up of the coal macromolecules becomes rate-determining. 98100534 Composition and morphology of fly ash from fluidized-bed combustion of brown coal Sykorova, I. et al. DGMK Tagungsber., 1997, 9703, 1187-l 190. The study determines the chemical composition and morphology of fly ash captured in cyclone, bottom ash, and ultrafine particles separated in the low pressure impactor produced by the two modes of combustion are determined The two type of brown coal from the North Bohemian basin is characterized by reflectance, maceral, mineralogical, and chemical composition Composition and morphology of fly ash depends on reaction conditions, coal quality, and size distribution of particles. 98loo535 Conversion of char nitrogen to N2 under incomplete combustion conditions Zhuang, Q.-L. et al. Sekitan Kagaku Kaigi Happy0 Ronbunshu, 1996, 33, 237-240. (In Japanese) A batch scale quartz-made fluidized bed reactor was employed to study the combustion of a char prepared from a Chinese lignite at 1123 K to confirm the parameters affecting the conversion of char-N to N:. Almost all of the N-containing gases during combustion was NZ under 02-lean conditions, and only small amounts of NH7 and HCN. However, no NO, and NzO were detected. The formation of Nz took place in the final stage of combustion, pyridinic-N disappeared completely and pyrrolic-N decreased, while Ocontaining nitrogen complexes became the main component. A mechanism for conversion reactions of char-N in combustion was discussed. 98100536 Dependence of single coal particle ignition mechanism on the surrounding volatile matter cloud Katalambula, H. et al. Energy Fuels, 1997, 11, (5), 1033-1039. Experiments were conducted to study the effect of volatile matter cloud surrounding a single coal particle on the ignition mechanism. Three different experimental conditions that had different convection intensities were used: microgravity with negligible convection, normal gravity with natural convection, and normal gravity with forced convection. Three types of coal with mean particle sizes of 0.8, 1.0, and 1.2 mm were ignited in air by heat radiation at heating rates of 770-900 K/s. Results showed that the amount of volatiles remaining in the vicinity of the particle is significantly
Fuel and Energy Abstracts
January 1998
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