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00280 Performance of natural gas cofiring on a coal-fired spreader stoker
03
Gaseous fuels
(sources,
properties,
recovery, treatment)
99lW280 Performance of natural gas cofirlng on a coalflred spreader stoker
99100285 A research of some problems of the exploration and exploitation of gas-bearing coal seam in Shanxi Province
Mason, H. B. et al. PWR (Am. Sot. Mechanical Eng.), 1996, 30, (2) 805821. Special challenges are created by a tightening of environmental regulations with coal fired stoker boilers where the moving bed firing configuration greatly limits operational flexibility. For stokers, gas cofiring is an efficient way to achieve compliance, enhance performance and treat operational problems. Firing from 5 to 30 percent of total heat input through side-wall gas burners offers a spectrum of benefits including faster and cleaner warmup and light-off, reduced opacity, recovered derate, coal flexibility, and improved turndown and load following. In this project, the 165,000 lb/h Babcock & Wilcox spreader stoker boiler at Dover Light & Power was retrofitted with dual Coen gas fired burners rated at 37 MMBtu/h each. A high-pressure drop burner design with a small throat opening was used to increase flame penetration into the combustion gases and minimize pressure part modifications. The gas burners in this staggered configuration promote better mixing and heat distribution and reduce the load per unit area on the grate. Test results show significant improvement in emissions efficiency and operability. Particulate emissions at the electrostatic precipitator inlet were reduced by an average of 25 percent with 10 percent cofire. Due to improved carbon utilization and reduced excess air firing from 8 to 10 percent of total heat input from gas increased boiler efficiency 2 to 3 percent. Carbon in fly ash was reduced by 35 to 40 percent by cofiring. Excess oxygen was a function of coal quality and was reduced up to 2 to 3 percent with gas cofiring. Operational improvements with cofire include ability to fire at loads above 145,000 to 150,000 lb/h which had previously been precluded by opacity emissions or fan limitations. Warm-up with gas from a cold start gave low opacity episodes compared to coal startup. To avoid opacity episodes, problematic coals, including fines up to 45 percent, were fired without reducing load or increasing excess air.
Zhang, H.-Y. and Liu, K. Proc. Annu. Int. Pittsburgh Cool Conf., 1997, 14, (4) 14-30. In this paper the problems concerning the formation of the Shanxi gasbearing coalbed are explored, its long-range analyses and the exploration and exploitation of the gas-bearing coalbed there. In the section about ‘The formation of Shanxi gas-bearing coalbed and its long-range analyses’ the following problems about coal field quality are explained: coal seam thickness, the permeability of the gas-bearing coalbed, overburden, the structure fracture, the seam mechanism of shear, the geological structure location etc. and under the premise of the long-range analyses, it is pointed out that the middle section of Hedong coal field (HCF), Qingsui coal field (QCF) and Xishan coal field (XCF) are the most favourable areas. In the section of ‘The exploration and its exploitation’ the chief works in each work stage are described as is the application of the means of exploration and the lay-out method of the exploration project, thus providing a reliable foundation for the reference of the gas-bearing exploration.
99/00281 Procedure and catalysts for the production of methanol from natural gas Boll, W. and Goehna, H. Appl., 19, 644, 216, 8 pp. (In German) A natural gas is catalytically reacted with steam and molar oxygen to give a synthesis gas mixture containing CO, Hz, and COz, which is mixed with a Ha-rich recycle gas and the mixture fed into a Copper catalyst-containing methanol-production reactor at with the methanol being removed from the product stream as a condensible vapour and the residual gas recycled in a specified manner.
Process and apparatus for catalytic partial oxldatlon of hydrocarbon for hydrogen and carbon monoxide manufacture
99/00282
Primdahl, I. I. Eur. Pat. Appl. EP 842,894 (Cl. COlB3/38), 20 May 1998, US Appl. 30,847, 15 Nov 1996; 5 pp. By catalytic partial oxidation of a hydrocarbon feed gas in a number of separate steps hydrogen and carbon monoxide containing-synthesis gas is manufactured. In each step only a small fraction of the stoichiometric amount of oxygen is added to the reaction and the feed gas is passed through a catalytic zone arranged in each step, so that complete conversion of the added amount of oxygen is obtained in each step.
Production of hot gas by the Fuerst Leopold/ Wulfen mlne drying plant using sewage sludge
99100283
Latsch, H. et al. Aujbereir. -Tech., 1998, 39, (4), 180-188. Reported are the experiences of a drying plant for coal washings with an atmospheric fluidized-bed furnace at the Forst LeopoldWulfen Mine (Germany) in which the raw washings (500 g/l) were replaced as fuel by activated presettled sludge. A new bag filter was integrated into the induced drought ventilator and chimney prior to operation with activated presettled sludge. The change of fuel required a license, which took into account the fact that the emission conditions and the emission levels could also be improved on the basis of the new technology. Six emission limits, the observance of which was not yet state-of-the-art, were permitted until 1996. In the meantime, only four emission limits are being exceeded for reasons of operational improvement work.
Removal electron attachment
99100284
of
aromatic
compounds
in gas
by
Tamon, H. et al. Ind. Eng Chemical Res., 1998, 37, (7), 2770-2774. In order to remove benzene and p-dichlorobenzene from nitrogen and a nitrogen+xygen mixture, a corona-discharge reactor was applied. Although benzene was not effectively removed from nitrogen by electron attachment, the removal efficiency was improved greatly by mixing oxygen. On the other hand, the high removal efficiencies of p-dichlorobenzene were obtained in nitrogen or a nitrogen-oxygen mixture. Based on the contribution of the ozone reaction and the analysis of the deposit on the anode of the reactor the removal mechanism was studied. As a result, the ozone reaction does not contribute to the removals. An FTIR measurement and thermogravimetry suggest that benzene or p-dichlorobenzene is decomposed by dissociative electron attachment and deposits as polycyclic aromatic compounds of a high boiling point on the anode surface.
28
Fuel and Energy Abstracts
January 1999
99lOO286 Stratigraphy and structure of coalbed methane reservoirs in the United States: An overview Pashin, J. C. Int. J. Cool Geol., 1998, 35, (l-4) 209-240. The shape, continuity and permeability of coal is determined by stratigraphy and geological structure which are therefore critical considerations for designing exploration and production strategies for coalbed methane. Coal in the USA is dominantly of Pennsylvanian, Cretaceous and Tertiary age, and to date, more than 90% of the coalbed methane produced is from Pennsylvanian and Cretaceous strata of the Black Warrior and San Juan Basins. Investigations of these basins establish that sequence stratigraphy is a promising approach for regional characterization of coalbed methane reservoirs. Coalbed methane production in the USA is mainly from foreland and intermontane basins containing diverse compressional and extensional structures. Balanced structural models can be used to construct and validate cross sections as well as to quantify layer-parallel strain and predict the distribution of fractures. Folds and faults influence gas and water production in diverse ways. However, the performance of individual wells is made difficult to predict by the interwell heterogeneity related to fractures and shear structures.
Structure and acoustic-pressure response hydrogen-oxygen diffusion flames at high pressure
99100287
of
Sohn, C. H. et al. Combustion and Flame, 1998, 115, (3) 299-312. Numerically studied are the flame structures and extinction characteristics of undiluted hydrogen-oxygen strained diffusion flames at high pressures with detailed and reduced chemistry and with an intention of application to acoustic instabilities of rocket engines. The numerical results of extinction strain rate for undiluted hydrogen-oxygen flames are found to be qualitatively different from those for hydrogen-air flames in that extinction strain rate for undiluted hydrogen-oxygen flames increases linearly with pressure up to 100 atm whereas extinction strain rate for hydrogen-air flames saturates around 50 atm. When the characteristic flow time is compared with the characteristic chemical time it reveals that extinction strain rate varies linearly with pressure for flames controlled by two-body chain-branching reactions that are found to be dominant up to 100 atm. Based on these results, the asymptotic methods, previously used in lowpressure hydrogen-air flames, can be extended to predict the asymptotic structure of hydrogen-oxygen flames at high pressures. On the other hand, the fall-off effect and real-gas effect are found to be minimal on extinction characteristics. Since the characteristic flow time is estimated to be several orders of magnitude shorter than the characteristic acoustic time in rocket engines, acoustic responses are satisfactorily reproduced from the quasisteady flame structures. 99lW288 Study of ammonia removal from coal-gasified fuel Hasegawa, T. and Sato, M. Combust. Flame, 1998, 114, (l/2), 246-258. Ammonia in gasified fuel, in integrated coal gasification combined-cycle power-generation (IGCC) systems, is passed through a hot/dry type gas clean-up facility into a gas turbine. The ammonia is converted to nitrogen oxides in the gas turbine combustion process. Therefore, ammonia removal from coal-gasified fuel effectively reduces NO, emissions in IGCC systems. The optimum NO/NH, ratio, the optimum concentration of added Oz. and the influence of CO, Hz. and CH4 in the coal-gasified fuel on NH3 decomposition and NO reduction were clarified through experiments using a tubular flow reactor and numerical analysis based on reaction kinetics. The main results were as follows. (1) The optimum NO/NH3 ratio for maximizing NH3 decomposition and NO reduction was about one. (2) The NH2 decomposition ratio depended only on Hz. and decreased rapidly with increasing H2 concentration. (3) The NO reduction ratio decreased with an increasing Hz concentration. (4) The remaining CHI, which was not decomposed by pyrolysis, increased with an increasing CH,, concentration and caused the reaction temperature to rise, as opposed to cases of CO and Hz. (5) In air-blown, coal-gasified fuel, the method was effective in decreasing total fixed nitrogen (TFN) by up to 40% and minimizing the total concentration of remaining NH2 and NO in air-blown.
Gaseous fuels
(sources,
properties,
recovery, treatment)
99lW280 Performance of natural gas cofirlng on a coalflred spreader stoker
99100285 A research of some problems of the exploration and exploitation of gas-bearing coal seam in Shanxi Province
Mason, H. B. et al. PWR (Am. Sot. Mechanical Eng.), 1996, 30, (2) 805821. Special challenges are created by a tightening of environmental regulations with coal fired stoker boilers where the moving bed firing configuration greatly limits operational flexibility. For stokers, gas cofiring is an efficient way to achieve compliance, enhance performance and treat operational problems. Firing from 5 to 30 percent of total heat input through side-wall gas burners offers a spectrum of benefits including faster and cleaner warmup and light-off, reduced opacity, recovered derate, coal flexibility, and improved turndown and load following. In this project, the 165,000 lb/h Babcock & Wilcox spreader stoker boiler at Dover Light & Power was retrofitted with dual Coen gas fired burners rated at 37 MMBtu/h each. A high-pressure drop burner design with a small throat opening was used to increase flame penetration into the combustion gases and minimize pressure part modifications. The gas burners in this staggered configuration promote better mixing and heat distribution and reduce the load per unit area on the grate. Test results show significant improvement in emissions efficiency and operability. Particulate emissions at the electrostatic precipitator inlet were reduced by an average of 25 percent with 10 percent cofire. Due to improved carbon utilization and reduced excess air firing from 8 to 10 percent of total heat input from gas increased boiler efficiency 2 to 3 percent. Carbon in fly ash was reduced by 35 to 40 percent by cofiring. Excess oxygen was a function of coal quality and was reduced up to 2 to 3 percent with gas cofiring. Operational improvements with cofire include ability to fire at loads above 145,000 to 150,000 lb/h which had previously been precluded by opacity emissions or fan limitations. Warm-up with gas from a cold start gave low opacity episodes compared to coal startup. To avoid opacity episodes, problematic coals, including fines up to 45 percent, were fired without reducing load or increasing excess air.
Zhang, H.-Y. and Liu, K. Proc. Annu. Int. Pittsburgh Cool Conf., 1997, 14, (4) 14-30. In this paper the problems concerning the formation of the Shanxi gasbearing coalbed are explored, its long-range analyses and the exploration and exploitation of the gas-bearing coalbed there. In the section about ‘The formation of Shanxi gas-bearing coalbed and its long-range analyses’ the following problems about coal field quality are explained: coal seam thickness, the permeability of the gas-bearing coalbed, overburden, the structure fracture, the seam mechanism of shear, the geological structure location etc. and under the premise of the long-range analyses, it is pointed out that the middle section of Hedong coal field (HCF), Qingsui coal field (QCF) and Xishan coal field (XCF) are the most favourable areas. In the section of ‘The exploration and its exploitation’ the chief works in each work stage are described as is the application of the means of exploration and the lay-out method of the exploration project, thus providing a reliable foundation for the reference of the gas-bearing exploration.
99/00281 Procedure and catalysts for the production of methanol from natural gas Boll, W. and Goehna, H. Appl., 19, 644, 216, 8 pp. (In German) A natural gas is catalytically reacted with steam and molar oxygen to give a synthesis gas mixture containing CO, Hz, and COz, which is mixed with a Ha-rich recycle gas and the mixture fed into a Copper catalyst-containing methanol-production reactor at with the methanol being removed from the product stream as a condensible vapour and the residual gas recycled in a specified manner.
Process and apparatus for catalytic partial oxldatlon of hydrocarbon for hydrogen and carbon monoxide manufacture
99/00282
Primdahl, I. I. Eur. Pat. Appl. EP 842,894 (Cl. COlB3/38), 20 May 1998, US Appl. 30,847, 15 Nov 1996; 5 pp. By catalytic partial oxidation of a hydrocarbon feed gas in a number of separate steps hydrogen and carbon monoxide containing-synthesis gas is manufactured. In each step only a small fraction of the stoichiometric amount of oxygen is added to the reaction and the feed gas is passed through a catalytic zone arranged in each step, so that complete conversion of the added amount of oxygen is obtained in each step.
Production of hot gas by the Fuerst Leopold/ Wulfen mlne drying plant using sewage sludge
99100283
Latsch, H. et al. Aujbereir. -Tech., 1998, 39, (4), 180-188. Reported are the experiences of a drying plant for coal washings with an atmospheric fluidized-bed furnace at the Forst LeopoldWulfen Mine (Germany) in which the raw washings (500 g/l) were replaced as fuel by activated presettled sludge. A new bag filter was integrated into the induced drought ventilator and chimney prior to operation with activated presettled sludge. The change of fuel required a license, which took into account the fact that the emission conditions and the emission levels could also be improved on the basis of the new technology. Six emission limits, the observance of which was not yet state-of-the-art, were permitted until 1996. In the meantime, only four emission limits are being exceeded for reasons of operational improvement work.
Removal electron attachment
99100284
of
aromatic
compounds
in gas
by
Tamon, H. et al. Ind. Eng Chemical Res., 1998, 37, (7), 2770-2774. In order to remove benzene and p-dichlorobenzene from nitrogen and a nitrogen+xygen mixture, a corona-discharge reactor was applied. Although benzene was not effectively removed from nitrogen by electron attachment, the removal efficiency was improved greatly by mixing oxygen. On the other hand, the high removal efficiencies of p-dichlorobenzene were obtained in nitrogen or a nitrogen-oxygen mixture. Based on the contribution of the ozone reaction and the analysis of the deposit on the anode of the reactor the removal mechanism was studied. As a result, the ozone reaction does not contribute to the removals. An FTIR measurement and thermogravimetry suggest that benzene or p-dichlorobenzene is decomposed by dissociative electron attachment and deposits as polycyclic aromatic compounds of a high boiling point on the anode surface.
28
Fuel and Energy Abstracts
January 1999
99lOO286 Stratigraphy and structure of coalbed methane reservoirs in the United States: An overview Pashin, J. C. Int. J. Cool Geol., 1998, 35, (l-4) 209-240. The shape, continuity and permeability of coal is determined by stratigraphy and geological structure which are therefore critical considerations for designing exploration and production strategies for coalbed methane. Coal in the USA is dominantly of Pennsylvanian, Cretaceous and Tertiary age, and to date, more than 90% of the coalbed methane produced is from Pennsylvanian and Cretaceous strata of the Black Warrior and San Juan Basins. Investigations of these basins establish that sequence stratigraphy is a promising approach for regional characterization of coalbed methane reservoirs. Coalbed methane production in the USA is mainly from foreland and intermontane basins containing diverse compressional and extensional structures. Balanced structural models can be used to construct and validate cross sections as well as to quantify layer-parallel strain and predict the distribution of fractures. Folds and faults influence gas and water production in diverse ways. However, the performance of individual wells is made difficult to predict by the interwell heterogeneity related to fractures and shear structures.
Structure and acoustic-pressure response hydrogen-oxygen diffusion flames at high pressure
99100287
of
Sohn, C. H. et al. Combustion and Flame, 1998, 115, (3) 299-312. Numerically studied are the flame structures and extinction characteristics of undiluted hydrogen-oxygen strained diffusion flames at high pressures with detailed and reduced chemistry and with an intention of application to acoustic instabilities of rocket engines. The numerical results of extinction strain rate for undiluted hydrogen-oxygen flames are found to be qualitatively different from those for hydrogen-air flames in that extinction strain rate for undiluted hydrogen-oxygen flames increases linearly with pressure up to 100 atm whereas extinction strain rate for hydrogen-air flames saturates around 50 atm. When the characteristic flow time is compared with the characteristic chemical time it reveals that extinction strain rate varies linearly with pressure for flames controlled by two-body chain-branching reactions that are found to be dominant up to 100 atm. Based on these results, the asymptotic methods, previously used in lowpressure hydrogen-air flames, can be extended to predict the asymptotic structure of hydrogen-oxygen flames at high pressures. On the other hand, the fall-off effect and real-gas effect are found to be minimal on extinction characteristics. Since the characteristic flow time is estimated to be several orders of magnitude shorter than the characteristic acoustic time in rocket engines, acoustic responses are satisfactorily reproduced from the quasisteady flame structures. 99lW288 Study of ammonia removal from coal-gasified fuel Hasegawa, T. and Sato, M. Combust. Flame, 1998, 114, (l/2), 246-258. Ammonia in gasified fuel, in integrated coal gasification combined-cycle power-generation (IGCC) systems, is passed through a hot/dry type gas clean-up facility into a gas turbine. The ammonia is converted to nitrogen oxides in the gas turbine combustion process. Therefore, ammonia removal from coal-gasified fuel effectively reduces NO, emissions in IGCC systems. The optimum NO/NH, ratio, the optimum concentration of added Oz. and the influence of CO, Hz. and CH4 in the coal-gasified fuel on NH3 decomposition and NO reduction were clarified through experiments using a tubular flow reactor and numerical analysis based on reaction kinetics. The main results were as follows. (1) The optimum NO/NH3 ratio for maximizing NH3 decomposition and NO reduction was about one. (2) The NH2 decomposition ratio depended only on Hz. and decreased rapidly with increasing H2 concentration. (3) The NO reduction ratio decreased with an increasing Hz concentration. (4) The remaining CHI, which was not decomposed by pyrolysis, increased with an increasing CH,, concentration and caused the reaction temperature to rise, as opposed to cases of CO and Hz. (5) In air-blown, coal-gasified fuel, the method was effective in decreasing total fixed nitrogen (TFN) by up to 40% and minimizing the total concentration of remaining NH2 and NO in air-blown.