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01488 A pressurized drop-tube furnace for coal reactivity studies
09
Combustion (burners, combustion systems)
Oxygen supply and safety control technology for 99101484 blast furnace oxy-coal injection process Liu, Y. et al. Gangtie, 1997,32, (7), 17-20. (In Chinese) For blast furnace oxy-coal injection, the requirements of oxygen supply and safety control were analysed. The general-pipe and sub-pipe oxygen supply systems and their safety control were compared and analysed. An integrated oxygen supply and safety control system were then derived.
Partitioning of potentially 99101485 ments In coal combustion
hazardous trace ele-
Davidson, R. M. Combust. Can. ‘96 Conf.: Future Changing Role Combust. Can. Effic. Environ., 1996, Paper23/1_Paper23/17. Of the various products arising from coal combustion, recent studies of the distribution of eleven trace elements identified as potentially hazardous are reviewed. In general, more then 99% of these trace elements with the exception of mercury and selenium can be captured in electrostatic precipitators. However, the concentrations of trace elements will be considered as a function of particle size, because the efficiency of ESPs is generally lowest in the 0.1-1.5 pm particle size range. There is evidence that the major minerals within coal can capture trace elements and prevent them from vapourizing. The speciation and affinities of trace elements in fly ash are also important: until recently, the procedures used could only reveal where the trace elements reside in the combustion products. There have been some developments in identifying the chemical state of the trace element compounds. A better knowledge of the behaviour and chemistry of trace elements should permit better modelling and prediction of their behaviour. Most of the models use mainly thermodynamic data and their shortcomings may be due to the formation of complex slags and glasses which are not taken into account. On the whole though, the models are quite successful and provide reasonable starting points for describing the behaviour of trace elements in coal combustion.
Practice of high-rate pulverized coal injection in 99101488 300 m3 blast furnaces at Ma’anshan iron & Steel Co. Xian, W. et al. Gun&e, 1997, 32, (12), 9-11. (In Chinese) A vanadium-titanium ore with a sinter rate of 90% was fed into a 300 m3 blast furnace at Ma’anshan Iron & Steel Co., China to achieve a high-rate (120-150 kg/ton) injection of pulverized coal. The blast temperature of 1070°C was obtained by average oxygen enrichment < 1% and by the highrate injection of pulverized coal containing 16% fines.
Preliminary analysts of the second generation coalfired atmospheric fluidized bed combined cycle (AFBC) Zhang, N. et al. Gongcheng Rewuli Xuebao, 1996, 17, (4), 385-388. (In
99101487
Chinese) An analysis of second generation coal-fired atmospheric fluidized bed combined cycle (AFBC) including the determination of common values of efficiency and power output ratio between gas turbine side and steam turbine side and an investigation into the effect of the main thermal parameters on performances. 99101488
A pressurized drop-tube furnace for coal reactivity
studies
Ouyang, S. et al. Rev. Sci. Instrum., 1998, 69, (8). 3036-3041. In this paper, the design and characterization of a pressurized drop-tube furnace for investigation of coal devolatilization, gasification and combustion are presented. The furnace is designed for high-temperature, isothermal operation in a developing laminar flow regime. It can be operated at pressures up to 1600 kPa and temperatures up to 1673 K, with variable reaction time, particle feeding rate and with inert and various oxidizing atmospheres. Particle residence times can be varied between -0.02 and -10 s depending upon operating conditions and positions of injection and sampling probes. Observations ports are available for sample collections and for optical investigation of the reactions or temperature measurements. Characterization of gas temperature in the furnace shows that, although the gas temperature profile in the furnace is affected by the water-cooled injection probe, the furnace is able to achieve isothermal operation in a developing laminar flow regime. The suitability of the furnace for experiments in coal research was demonstrated by results from a series of brown coal devolatilization tests.
Proceedings of the 14th international conference 99101489 on fluidized bed combustion, volume 2, held 11-14 May 1997, in Vancouver, Canada Preto, F. D. S.
Editor
(ASME: New York),
1997, 663 pp.
A process simulation model for a 2 ton h-’ Incinerator (a combined bed combustion and furnace heat transfer model)
99101490
Yang, W. et al. Int. 1. Energy Res., 1998, 22, (ll), 943-951. For a 2 ton h-’ Incinerator a process simulation model was constructed. The simulation model was designed to provide system performance parameters according to various operating conditions. In accommodating the wide variation of quality and composition of input wastes, the plant operating parameters such as amount of excess air, pre-heated air temperature, waste feed rate and primary air distribution over the stoker etc., must be carefully controlled. The proposed model calculates operating variables of each submodule, by employing steady-state thermal and material balance equations. Combustion of waste bed and its radiative
150
Fuel and Energy Abstnrcts
March 1999
heat transfer in the combustion chamber are considered. The calculated results of the combustion chamber performance are evaluated, in terms of temperature, locations and width of the flame band and mean residence time in the secondary combustion chamber. These results are compared with a limited set of field test measurements for verification of the model. 99101491 Pyrolysis of sewage sludge as treatment process for the thermal utilization in firing places Storm,C. ef al. DGMK Tagungsber, 1998, 9802, 303-310. (In German) In a pilot plant, the utilization of pyrolysis gas from sewage sludge as secondary fuel for NO, reduction in a coal dust firing was studied. Entrained gasification was performed at 500-1100°C and the obtained gas was used for NO, reduction at various air ratios. The release of NO, could be decreased to ~200 mg/m3. The influence of the gasification temperature on gas yield and composition and on the properties of the solid residue was also determined. Of heavy metals in the solid matrix elution experiments of the solid residues revealed the strong bonding. 99101492 Research on agglomeration in coal gasifier with twin fluidized beds
Xiong, Y. et al. Meitan Zhuanhua, 1997, 20, (2). 75-79. (In Chinese) Studied was the mechanism of agglomeration and defluidization process in a coal gasifier with twin fluidized beds. Optical microscope, X-ray diffraction (XRD) and thermogravimetric analysis were carried out on the samples of agglomerates which caused the defluidization in a coal gasifier with twin fluidized beds. The results showed that molten alkali and alkaline earth sulfates in coal were formed on the char’s surface and that the molten ash matrix on the char transferred to the surface of bed particles, caused them to form agglomerates as the result of random collisions between the bed particles coated with low-temperature compounds and caused the defluidization in the coal gasifier. Some suggestions were made on how to prevent the gasifier from defluidization and agglomeration.
Research on NO. formation characteristics 99101493 pulverized burner with boat-shaped flame stabilizer
Zhong, B. and Xu, X. Gongcheng Rewuli Xuebao. (In Chinese) A study of the characteristics of NO, formation in a with a boat-shaped flame stabilizer. A ‘three-zone’ sible for NO, reduction in the burner and enhanced coal flames.
in
1996, 17, (4). 497-500. pulverized coal burner structure was responstability of pulverized
99101494 Restraining NO, formation during coal combustion in packed bed Wu, S. et al. J. Univ. Sci. Technol. Beijing, 1998, 5, (2), 70-74. This paper studied the effects of various combustion conditions on reducing conversion of NO, during coal combustion. Under these conditions, coals with smaller particle size gave a lower conversion to NO,, as expected with a decrease in overall stoichiometric ratio. Either a decrease in 02 content in combustion gas or an increase in coal content in the fuel bed would lead to a lower conversion of NO,. In order to investigate the effect of metallic oxide layers on the inhibition of NO, formation, combustion experiments on coal granules with a layer of various metallic oxides, including Fe203, Ni203 and mixed iron-nickel oxides, were conducted in a packed-bed combustor. These experiments have shown that during coal combustion, most of the metal oxide layers had a considerable effect on reduction of NO, emissions.
99101495 Results of using technical grade nitrogen in blast furnace blowing to enhance efficient use of coke Dyshlevich,I. I. et al. Stal’, 1998, (2), 5-8. (In Russian) There was a decrease in coke consumption of 5.1% when the nitrogen content was increased by 1.6% in the blast and the hot blast temperature was increased by 95°C of ironmaking blast furnaces. The overall economic effect of increasing the nitrogen concentration in the blast is dependent of local conditions and relationship between the electric energy and coke costs and their availability.
99101498 Reversed air staging - a method for reduction of N20 emlssions from fluidized bed combustion of coal Lyngfelt,A. et al. Fuel, 1998, 77, (9/10), 953-959. Reversed air staging is a method for reducing NzO emissions from coal combustion. This paper investigates reversed air staging in a 12 MW circulating fluidized bed boiler and looks at the effect of combustor airratio, bed temperature, load and limestone addition ratio. At a temperature of 850°C and with maintained low emissions of NO, SO* and CO, N20 emissions can be decreased to one quarter compared to normal air staging by only changing the air distribution. With increased bed temperature, 870°C. in combination with increased limestone addition, from calcium/ sulfur molar ratio = 3 to 4, it was possible to reduce NzO by 90 ~01% with low emissions of NO, SOz and CO. The method was less efficient at low load, because of the lower cyclone temperature. The effect of redistribution of some of the air added in the cyclone outlet to the cyclone inlet was studied and found not to give any improvement in the boiler used compared to adding all of the air in the cyclone outlet. There was no significant difference in combustion efficiency between reversed air staging and normal air staging.
Combustion (burners, combustion systems)
Oxygen supply and safety control technology for 99101484 blast furnace oxy-coal injection process Liu, Y. et al. Gangtie, 1997,32, (7), 17-20. (In Chinese) For blast furnace oxy-coal injection, the requirements of oxygen supply and safety control were analysed. The general-pipe and sub-pipe oxygen supply systems and their safety control were compared and analysed. An integrated oxygen supply and safety control system were then derived.
Partitioning of potentially 99101485 ments In coal combustion
hazardous trace ele-
Davidson, R. M. Combust. Can. ‘96 Conf.: Future Changing Role Combust. Can. Effic. Environ., 1996, Paper23/1_Paper23/17. Of the various products arising from coal combustion, recent studies of the distribution of eleven trace elements identified as potentially hazardous are reviewed. In general, more then 99% of these trace elements with the exception of mercury and selenium can be captured in electrostatic precipitators. However, the concentrations of trace elements will be considered as a function of particle size, because the efficiency of ESPs is generally lowest in the 0.1-1.5 pm particle size range. There is evidence that the major minerals within coal can capture trace elements and prevent them from vapourizing. The speciation and affinities of trace elements in fly ash are also important: until recently, the procedures used could only reveal where the trace elements reside in the combustion products. There have been some developments in identifying the chemical state of the trace element compounds. A better knowledge of the behaviour and chemistry of trace elements should permit better modelling and prediction of their behaviour. Most of the models use mainly thermodynamic data and their shortcomings may be due to the formation of complex slags and glasses which are not taken into account. On the whole though, the models are quite successful and provide reasonable starting points for describing the behaviour of trace elements in coal combustion.
Practice of high-rate pulverized coal injection in 99101488 300 m3 blast furnaces at Ma’anshan iron & Steel Co. Xian, W. et al. Gun&e, 1997, 32, (12), 9-11. (In Chinese) A vanadium-titanium ore with a sinter rate of 90% was fed into a 300 m3 blast furnace at Ma’anshan Iron & Steel Co., China to achieve a high-rate (120-150 kg/ton) injection of pulverized coal. The blast temperature of 1070°C was obtained by average oxygen enrichment < 1% and by the highrate injection of pulverized coal containing 16% fines.
Preliminary analysts of the second generation coalfired atmospheric fluidized bed combined cycle (AFBC) Zhang, N. et al. Gongcheng Rewuli Xuebao, 1996, 17, (4), 385-388. (In
99101487
Chinese) An analysis of second generation coal-fired atmospheric fluidized bed combined cycle (AFBC) including the determination of common values of efficiency and power output ratio between gas turbine side and steam turbine side and an investigation into the effect of the main thermal parameters on performances. 99101488
A pressurized drop-tube furnace for coal reactivity
studies
Ouyang, S. et al. Rev. Sci. Instrum., 1998, 69, (8). 3036-3041. In this paper, the design and characterization of a pressurized drop-tube furnace for investigation of coal devolatilization, gasification and combustion are presented. The furnace is designed for high-temperature, isothermal operation in a developing laminar flow regime. It can be operated at pressures up to 1600 kPa and temperatures up to 1673 K, with variable reaction time, particle feeding rate and with inert and various oxidizing atmospheres. Particle residence times can be varied between -0.02 and -10 s depending upon operating conditions and positions of injection and sampling probes. Observations ports are available for sample collections and for optical investigation of the reactions or temperature measurements. Characterization of gas temperature in the furnace shows that, although the gas temperature profile in the furnace is affected by the water-cooled injection probe, the furnace is able to achieve isothermal operation in a developing laminar flow regime. The suitability of the furnace for experiments in coal research was demonstrated by results from a series of brown coal devolatilization tests.
Proceedings of the 14th international conference 99101489 on fluidized bed combustion, volume 2, held 11-14 May 1997, in Vancouver, Canada Preto, F. D. S.
Editor
(ASME: New York),
1997, 663 pp.
A process simulation model for a 2 ton h-’ Incinerator (a combined bed combustion and furnace heat transfer model)
99101490
Yang, W. et al. Int. 1. Energy Res., 1998, 22, (ll), 943-951. For a 2 ton h-’ Incinerator a process simulation model was constructed. The simulation model was designed to provide system performance parameters according to various operating conditions. In accommodating the wide variation of quality and composition of input wastes, the plant operating parameters such as amount of excess air, pre-heated air temperature, waste feed rate and primary air distribution over the stoker etc., must be carefully controlled. The proposed model calculates operating variables of each submodule, by employing steady-state thermal and material balance equations. Combustion of waste bed and its radiative
150
Fuel and Energy Abstnrcts
March 1999
heat transfer in the combustion chamber are considered. The calculated results of the combustion chamber performance are evaluated, in terms of temperature, locations and width of the flame band and mean residence time in the secondary combustion chamber. These results are compared with a limited set of field test measurements for verification of the model. 99101491 Pyrolysis of sewage sludge as treatment process for the thermal utilization in firing places Storm,C. ef al. DGMK Tagungsber, 1998, 9802, 303-310. (In German) In a pilot plant, the utilization of pyrolysis gas from sewage sludge as secondary fuel for NO, reduction in a coal dust firing was studied. Entrained gasification was performed at 500-1100°C and the obtained gas was used for NO, reduction at various air ratios. The release of NO, could be decreased to ~200 mg/m3. The influence of the gasification temperature on gas yield and composition and on the properties of the solid residue was also determined. Of heavy metals in the solid matrix elution experiments of the solid residues revealed the strong bonding. 99101492 Research on agglomeration in coal gasifier with twin fluidized beds
Xiong, Y. et al. Meitan Zhuanhua, 1997, 20, (2). 75-79. (In Chinese) Studied was the mechanism of agglomeration and defluidization process in a coal gasifier with twin fluidized beds. Optical microscope, X-ray diffraction (XRD) and thermogravimetric analysis were carried out on the samples of agglomerates which caused the defluidization in a coal gasifier with twin fluidized beds. The results showed that molten alkali and alkaline earth sulfates in coal were formed on the char’s surface and that the molten ash matrix on the char transferred to the surface of bed particles, caused them to form agglomerates as the result of random collisions between the bed particles coated with low-temperature compounds and caused the defluidization in the coal gasifier. Some suggestions were made on how to prevent the gasifier from defluidization and agglomeration.
Research on NO. formation characteristics 99101493 pulverized burner with boat-shaped flame stabilizer
Zhong, B. and Xu, X. Gongcheng Rewuli Xuebao. (In Chinese) A study of the characteristics of NO, formation in a with a boat-shaped flame stabilizer. A ‘three-zone’ sible for NO, reduction in the burner and enhanced coal flames.
in
1996, 17, (4). 497-500. pulverized coal burner structure was responstability of pulverized
99101494 Restraining NO, formation during coal combustion in packed bed Wu, S. et al. J. Univ. Sci. Technol. Beijing, 1998, 5, (2), 70-74. This paper studied the effects of various combustion conditions on reducing conversion of NO, during coal combustion. Under these conditions, coals with smaller particle size gave a lower conversion to NO,, as expected with a decrease in overall stoichiometric ratio. Either a decrease in 02 content in combustion gas or an increase in coal content in the fuel bed would lead to a lower conversion of NO,. In order to investigate the effect of metallic oxide layers on the inhibition of NO, formation, combustion experiments on coal granules with a layer of various metallic oxides, including Fe203, Ni203 and mixed iron-nickel oxides, were conducted in a packed-bed combustor. These experiments have shown that during coal combustion, most of the metal oxide layers had a considerable effect on reduction of NO, emissions.
99101495 Results of using technical grade nitrogen in blast furnace blowing to enhance efficient use of coke Dyshlevich,I. I. et al. Stal’, 1998, (2), 5-8. (In Russian) There was a decrease in coke consumption of 5.1% when the nitrogen content was increased by 1.6% in the blast and the hot blast temperature was increased by 95°C of ironmaking blast furnaces. The overall economic effect of increasing the nitrogen concentration in the blast is dependent of local conditions and relationship between the electric energy and coke costs and their availability.
99101498 Reversed air staging - a method for reduction of N20 emlssions from fluidized bed combustion of coal Lyngfelt,A. et al. Fuel, 1998, 77, (9/10), 953-959. Reversed air staging is a method for reducing NzO emissions from coal combustion. This paper investigates reversed air staging in a 12 MW circulating fluidized bed boiler and looks at the effect of combustor airratio, bed temperature, load and limestone addition ratio. At a temperature of 850°C and with maintained low emissions of NO, SO* and CO, N20 emissions can be decreased to one quarter compared to normal air staging by only changing the air distribution. With increased bed temperature, 870°C. in combination with increased limestone addition, from calcium/ sulfur molar ratio = 3 to 4, it was possible to reduce NzO by 90 ~01% with low emissions of NO, SOz and CO. The method was less efficient at low load, because of the lower cyclone temperature. The effect of redistribution of some of the air added in the cyclone outlet to the cyclone inlet was studied and found not to give any improvement in the boiler used compared to adding all of the air in the cyclone outlet. There was no significant difference in combustion efficiency between reversed air staging and normal air staging.