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03731 Dry desulfurization apparatus
03
product into a lighter and heavier fraction, hydrotreating, and combining the hydrotreated product with the lighter fraction that has not been hydrotreated. Thermal cracking of coal residues: kinetics of 97103724 asphaltene decomposition Martinez, M. T. et al. Fuel, 1997, 76, (9). 871-877. Thermal cracking was used to process an asphaltenic residue from a synthetic crude obtained by coal liquefaction. The formation kinetics of oil + gas and coke (toluene-insoluble) from conversion of the asphaltenic fraction were determined. A three-lump model is proposed which considers parallel reactions for oil + gas and coke formation. Conversion data fitted second-order kinetics throughout for asphaltene conversion and oil + gas and coke formation. Delplot analysis indicated that under the most severe experimental conditions, asphaltenes and oils participated in secondary coke-forming reactions which are not included in the model. Structural analysis showed lower aromaticity and higher H/C and N/C ratios in the oil from the products than from the feed. Utility applications for coal water slurry cofiring 97103725 Battista, J. J. ef al. Proc. Int. Tech. Conf: Coal Util. F[tel Syst., 1995, 20, 523-534.
The paper discusses the co-firing of low-solids coal aqueous slurries with pulverized coal in a utility scale boiler using fines directly from coal cleaning circuits. Utilization of coal pond fines as feedstock for coal97103726 water slurry fuels Miller, S. F. et ul. Proc. Int. Tech. Conf Coal WI. Fuel Sy.st., 1995. 20, 535545.
03
GASEOUS Sources,
FUELS
Properties,
Recovery,
Treatment
Analysis of gaseous fuel and air mixing in flames 97103727 and flame quenching Brasaveanu. D. Proc. ht. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 701713. Based on the ideal gas law, the energy equation, the equation of continuity and Arrhenius farm of rate equation, a model for fuel-air mixing in flames is presented and applied to study the mixing and quenching of methane-air flames. The model is valid for mixtures of low density. In the absence of preferential diffusion, chemical reactions cause an unbalanced consumption of fuel and oxygen in non-stoichiametric flames. Until the desired equivalence ratio is achieved, enhanced preferential diffusion of oxygen or fuel is required in fuel-rich or fuel-lean flames, respectively. After desired equivalence ratio is achieved, preferential diffusion of oxygen or fuel should be reduced to the exact level required to compensate the unbalanced consumption of fuel and air. In the absence of these conditions, flame chemical cannot be strictly controlled. In addition, unless the desired equivalence ratio is at a position of stable equilibrium over an extended range of operational conditions, the flame may be quenched. Net transport of fuel or oxygen due to diffusion is correlated with distributions of pressure, temperature, velocity, species mass fraciions and heat transfer through radiation and conduction. Results show that negative rates of pressure and positive rates of pressure can enhance preferential diffusion of oxygen and fuel, respectively. Negative velocity divergence also enhances diffusion of oxygen, while positive velocity divergence enhances diffusion of fuel. Recirculation of burnt gases improves the stability of all flames. For rates of pressure of
Gaseous fuels (sources, properties,
recovery, treatment)
injected into CBM reservoirs to produce more CH+ Furthermore, a simple mass balance argument, based on a two to one coal-sorption-selectivity for COz over CH4, makes the building and operating fossil-fuelled green power plants feasible. Development of a catalyst for low-temperature 97103729 hydrolysis of carbonyl sulfide in coke oven gas Yashikawa, F. et al. Kagaku Kogaku Ronhun~hu, 1997. 23, (3), 371-377. (In Japanese) It is necessary to reduce or eliminate various impurities, especially sulfur compounds, found in coke oven gas (COG), before it can be used as a chemical feedstock and/or city gas. Catalysts active at around room temperature were explored as a means of removing a sulfur compound, carbonyl sulfide (COS), through catalytic hydrolysis at low temperature. An alumina impregnated with potassium carbonate was found to show high catalytic activity. COS was hydrolysed in the low temperature range of 10 and 80°C. The reaction rate was first order with respect to COS and zero order with respect to water. However, the rate decreased rapidly as the water vapour pressure increased in the region over approximately 1.5 kPa at 40°C because the hydrolysis reaction was inhibited by a large amount of water adsorbed on the catalyst. In COG containing large amounts of hydrocarbons and carbon dioxide, the developed catalyst exhibited high long-term activity for COS hydrolysis at between 40 and 50°C under atmospheric pressure. Development of regenerable copper-based sor97103730 bents for hot gas desulfurization Abbasian, J. et al. Proc. Int. Tech. Conf. Coal Util. FL(el Syst., 1996, 21, 1% 26. In integrated gasification combined cycle (IGCC) processes, solid fuels such as coal are gasified and the fuel gas produced is cleaned and combusted in a gas turbine. IGCC plants with hot fuel gas cleanup systems are superior to conventional pulverized coal-fired power plants because they offer higher power generation efficiency, higher power-to-heat ratio for cogeneration, superior environmental performance, and simpler plant configuration and modularity. The implementation of hot gas cleanup systems heavily depends on the development of regenerable sorbents for removal of sulfur-containing species from the fuel gas stream at elevated temperature from levels of several thousand ppm down to a few ppm. over many sulfidationiregeneration cycles. In addition, these sorbents must have high sulfur capacity, good sulfidation kinetics, good mechanical strength. and good chemical and structural stability over multicycle testing. Zincbased sorbents. the leading contenders for hot gas desulfurization, have been shown to suffer from zinc volatilization at elevated temperature, resulting in sorbent deterioration and losses through attrition and loss of reactivity. This leads to increasing sorbent replacement costs and overall cost of electricity. Copper-based sorbents do not suffer from volatilization problems. but bulk copper oxide is easily reduced to elemental copper in a reducing fuel gas environment, which in turn results in insufficient level of desulfurization. Fortunately, its performance can be greatly enhanced by combining copper oxide with other oxides to minimize or prevent sorbent reduction during the sulfidation stage. This paper reports on research conducted on the development of copper-based sorbents for hot coal gas desulfurization. The results of packed-bed experiments are presented and discussed. 97103731 Dry desulfurization apparatus Hashimoto, K. Jpn. Kokai Tokkyo Koho JP 09,132,785 [97,132,785] (Cl. ClOJ3/46), 20 May 1997, Appl. 95/292,541, 10 Nov 1995, 6 pp. (In Japanese) Sulfur compounds removal from a crude gas dry desulfurization apparatus is used. It operates at high-temperature and high-pressure in a fluidized desulfurization tower equipped with an ambient-pressure regeneration tower, a makeup drum for regeneration tower, a regenerated desulfurizer drum, a makeup drum for desulfurization tower (A), a sulfided desulfurizer drum (B), and desulfurizer conveying apparatus. (A) and (B) can be operated at varying pressures by controlling the up and down valves of each drum such that the desulfurization tower is operated at high pressure and the desulfurizer can be recycled between the desulfurization tower and the regeneration tower. Low-pressure air generated by an air blower can be used as regenerating gas and offgas from the regeneration tower is introduced to a flue gas treatment apparatus without further recycle. 97103732 Gas refining system Tatani, A. et al. Eur. Pat. Appl. EP 768,364 (Cl. ClOKl/26), 16 Apr 1997, JP Appl. 95/263,105,11 Ott 1995, 18 pp. This paper presents a gas refining system wherein a high-temperature and high-pressure reducing gas is introduced into a fixed-bed desulfurizer packed with an adsorbent by which sulfur compounds contained in the reducing gas are adsorbed and removed in the form of a sulfide. The adsorbent having the sulfide adsorbed thereon is regenerated by roasting with a regenerating gas containing oxygen. The gas refining system is equipped with oxygen concentration control means for controlling the oxygen concentration in the regenerating gas introduced into the desulfurizer to keep the internal temperature of the desulfurizer during the regeneration reaction suitable for the adsorbent. This invention includes an embodiment in which the exhaust gas obtained after the regeneration reaction gas is brought into contact with a calcium compoundcontaining slurry is recycled to the desulfurizer for use as the regenerating
Fuel and Energy Abstracts
September
1997
313
product into a lighter and heavier fraction, hydrotreating, and combining the hydrotreated product with the lighter fraction that has not been hydrotreated. Thermal cracking of coal residues: kinetics of 97103724 asphaltene decomposition Martinez, M. T. et al. Fuel, 1997, 76, (9). 871-877. Thermal cracking was used to process an asphaltenic residue from a synthetic crude obtained by coal liquefaction. The formation kinetics of oil + gas and coke (toluene-insoluble) from conversion of the asphaltenic fraction were determined. A three-lump model is proposed which considers parallel reactions for oil + gas and coke formation. Conversion data fitted second-order kinetics throughout for asphaltene conversion and oil + gas and coke formation. Delplot analysis indicated that under the most severe experimental conditions, asphaltenes and oils participated in secondary coke-forming reactions which are not included in the model. Structural analysis showed lower aromaticity and higher H/C and N/C ratios in the oil from the products than from the feed. Utility applications for coal water slurry cofiring 97103725 Battista, J. J. ef al. Proc. Int. Tech. Conf: Coal Util. F[tel Syst., 1995, 20, 523-534.
The paper discusses the co-firing of low-solids coal aqueous slurries with pulverized coal in a utility scale boiler using fines directly from coal cleaning circuits. Utilization of coal pond fines as feedstock for coal97103726 water slurry fuels Miller, S. F. et ul. Proc. Int. Tech. Conf Coal WI. Fuel Sy.st., 1995. 20, 535545.
03
GASEOUS Sources,
FUELS
Properties,
Recovery,
Treatment
Analysis of gaseous fuel and air mixing in flames 97103727 and flame quenching Brasaveanu. D. Proc. ht. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 701713. Based on the ideal gas law, the energy equation, the equation of continuity and Arrhenius farm of rate equation, a model for fuel-air mixing in flames is presented and applied to study the mixing and quenching of methane-air flames. The model is valid for mixtures of low density. In the absence of preferential diffusion, chemical reactions cause an unbalanced consumption of fuel and oxygen in non-stoichiametric flames. Until the desired equivalence ratio is achieved, enhanced preferential diffusion of oxygen or fuel is required in fuel-rich or fuel-lean flames, respectively. After desired equivalence ratio is achieved, preferential diffusion of oxygen or fuel should be reduced to the exact level required to compensate the unbalanced consumption of fuel and air. In the absence of these conditions, flame chemical cannot be strictly controlled. In addition, unless the desired equivalence ratio is at a position of stable equilibrium over an extended range of operational conditions, the flame may be quenched. Net transport of fuel or oxygen due to diffusion is correlated with distributions of pressure, temperature, velocity, species mass fraciions and heat transfer through radiation and conduction. Results show that negative rates of pressure and positive rates of pressure can enhance preferential diffusion of oxygen and fuel, respectively. Negative velocity divergence also enhances diffusion of oxygen, while positive velocity divergence enhances diffusion of fuel. Recirculation of burnt gases improves the stability of all flames. For rates of pressure of
Gaseous fuels (sources, properties,
recovery, treatment)
injected into CBM reservoirs to produce more CH+ Furthermore, a simple mass balance argument, based on a two to one coal-sorption-selectivity for COz over CH4, makes the building and operating fossil-fuelled green power plants feasible. Development of a catalyst for low-temperature 97103729 hydrolysis of carbonyl sulfide in coke oven gas Yashikawa, F. et al. Kagaku Kogaku Ronhun~hu, 1997. 23, (3), 371-377. (In Japanese) It is necessary to reduce or eliminate various impurities, especially sulfur compounds, found in coke oven gas (COG), before it can be used as a chemical feedstock and/or city gas. Catalysts active at around room temperature were explored as a means of removing a sulfur compound, carbonyl sulfide (COS), through catalytic hydrolysis at low temperature. An alumina impregnated with potassium carbonate was found to show high catalytic activity. COS was hydrolysed in the low temperature range of 10 and 80°C. The reaction rate was first order with respect to COS and zero order with respect to water. However, the rate decreased rapidly as the water vapour pressure increased in the region over approximately 1.5 kPa at 40°C because the hydrolysis reaction was inhibited by a large amount of water adsorbed on the catalyst. In COG containing large amounts of hydrocarbons and carbon dioxide, the developed catalyst exhibited high long-term activity for COS hydrolysis at between 40 and 50°C under atmospheric pressure. Development of regenerable copper-based sor97103730 bents for hot gas desulfurization Abbasian, J. et al. Proc. Int. Tech. Conf. Coal Util. FL(el Syst., 1996, 21, 1% 26. In integrated gasification combined cycle (IGCC) processes, solid fuels such as coal are gasified and the fuel gas produced is cleaned and combusted in a gas turbine. IGCC plants with hot fuel gas cleanup systems are superior to conventional pulverized coal-fired power plants because they offer higher power generation efficiency, higher power-to-heat ratio for cogeneration, superior environmental performance, and simpler plant configuration and modularity. The implementation of hot gas cleanup systems heavily depends on the development of regenerable sorbents for removal of sulfur-containing species from the fuel gas stream at elevated temperature from levels of several thousand ppm down to a few ppm. over many sulfidationiregeneration cycles. In addition, these sorbents must have high sulfur capacity, good sulfidation kinetics, good mechanical strength. and good chemical and structural stability over multicycle testing. Zincbased sorbents. the leading contenders for hot gas desulfurization, have been shown to suffer from zinc volatilization at elevated temperature, resulting in sorbent deterioration and losses through attrition and loss of reactivity. This leads to increasing sorbent replacement costs and overall cost of electricity. Copper-based sorbents do not suffer from volatilization problems. but bulk copper oxide is easily reduced to elemental copper in a reducing fuel gas environment, which in turn results in insufficient level of desulfurization. Fortunately, its performance can be greatly enhanced by combining copper oxide with other oxides to minimize or prevent sorbent reduction during the sulfidation stage. This paper reports on research conducted on the development of copper-based sorbents for hot coal gas desulfurization. The results of packed-bed experiments are presented and discussed. 97103731 Dry desulfurization apparatus Hashimoto, K. Jpn. Kokai Tokkyo Koho JP 09,132,785 [97,132,785] (Cl. ClOJ3/46), 20 May 1997, Appl. 95/292,541, 10 Nov 1995, 6 pp. (In Japanese) Sulfur compounds removal from a crude gas dry desulfurization apparatus is used. It operates at high-temperature and high-pressure in a fluidized desulfurization tower equipped with an ambient-pressure regeneration tower, a makeup drum for regeneration tower, a regenerated desulfurizer drum, a makeup drum for desulfurization tower (A), a sulfided desulfurizer drum (B), and desulfurizer conveying apparatus. (A) and (B) can be operated at varying pressures by controlling the up and down valves of each drum such that the desulfurization tower is operated at high pressure and the desulfurizer can be recycled between the desulfurization tower and the regeneration tower. Low-pressure air generated by an air blower can be used as regenerating gas and offgas from the regeneration tower is introduced to a flue gas treatment apparatus without further recycle. 97103732 Gas refining system Tatani, A. et al. Eur. Pat. Appl. EP 768,364 (Cl. ClOKl/26), 16 Apr 1997, JP Appl. 95/263,105,11 Ott 1995, 18 pp. This paper presents a gas refining system wherein a high-temperature and high-pressure reducing gas is introduced into a fixed-bed desulfurizer packed with an adsorbent by which sulfur compounds contained in the reducing gas are adsorbed and removed in the form of a sulfide. The adsorbent having the sulfide adsorbed thereon is regenerated by roasting with a regenerating gas containing oxygen. The gas refining system is equipped with oxygen concentration control means for controlling the oxygen concentration in the regenerating gas introduced into the desulfurizer to keep the internal temperature of the desulfurizer during the regeneration reaction suitable for the adsorbent. This invention includes an embodiment in which the exhaust gas obtained after the regeneration reaction gas is brought into contact with a calcium compoundcontaining slurry is recycled to the desulfurizer for use as the regenerating
Fuel and Energy Abstracts
September
1997
313