- Email: [email protected]
Effective conversion of CO2 to valuable compounds by using multi-functional catalysts
03 Gaseous fuels (derived gaseous fuels) Simulation of a spouted-bed coal gasifier based on the code ‘FLUENT’ is described, and especially, the development of particle adhesion model is discussed. By comparing with the experimental results of a 50 ton/day coal gasifier HYCOL, it is shown that the ash-viscosity-based particle adhesion model is effective in predicting the performance inside a slag-tap coal gasifier. 02/00317 Devolatiliration rate of Nigerian bituminous coal particles in shallow beds Adeyinka, J.S., Akimbode, F.O. Indian J. Eng. Mater. Sci, 2000, 7, (1) 47-50. Coal gasification studies were carried out on Lafia Obi bituminous coal (LOB) by using varying coal particle sizes to determine devolatilization rate. Particle size and coal chemistry affected devolatilization while fluidizing velocity and bed temperature play no significant role on devolatilization, between 800-900°C. Reduction in coal size increases devolatilization and burning rate at increased temperature nut with a decrease in devolatilization rate at increased mass charge leads to lower rate of in-bed-burning rate. Volatile emission was used to evaluate energy-mass balance of an adiabatic gasification. 02/00319 Direct conversion of methane and carbon dioxide to higher hydrocarbons by using catalytic dielectric-barrier discharges with reolites Eliasson, B. Ed al. 2nd. Eng. Chem. Res., 2000, 39, (5). 1221-1227. Direct higher hydrocarbon formation from the greenhouse gases methane and carbon dioxide by using a dielectric-barrier discharge (DBD) with zeolite catalysts is presented. This catalytic DBD can be operated at ambient conditions and leads to direct hydrocarbon formation. The products include alkanes, alkenes, oxygenates, and syngas (CO + Hz). The product distribution depends on the pressure, the input power, the flow rate, the CHJCOs feed ratio, and the catalyst used. It is not sensitive to gas temperature in the range from room temperature to 150°C. From the experiments it can be concluded that a cogeneration of syngas and higher hydrocarbons can be achieved by using the catalytic DBD. The optimum CHJCOz ratio in the feed for such cogeneration is in the range 2/l to 3/l. The energy efficiency of CO* and CH4 conversion increases substantially at higher discharge powers. 02/00319 Distribution and catalytic activity of eutectic salts in steam gasification of coal Godavarty, A., Aganval, A. Energy Fuels, 2000, 14, (3), 558-565. The reactivity of coal char in steam is enhanced by the addition of binary and ternary eutectic alkali salts due to their reduced melting points. The cataytic steam gasification of Illinois No. 6 coal was carried out using binary (NasCOs-Kz-COs) and ternary (LizCOs-NaaCOsKsCOs) eutectic salt mixtures in a fixed bed reactor at different catalyst loadings. For the same catalyst loading, the ternary catalyst showed higher carbon conversions compared to the binary catalyst. The physical distribution of both catalyst systems on the coal char surface was examined using a scanning electron microscope. Both catalysts showed uniform dispersion on the coal matrix indicating homogeneous physical mixing. An attempt has been made to establish a qualitative correlation between the type of catalyst, its distribution, and effect on the overall carbon conversions. Gasified chars were highly porous in nature and coalesce in the case of the binary catalyst whereas the ternary catalyst showed highly porous and crystallographic morphology X-ray diffraction spectra showed the formation of potassium polysulphides (KxSy) in the gasified chars of the eutectic catalyst systems. 02/00320 Dynamic behavior of stratified downdraft gasifiers Blasi, C.D. Chem. Eng. Sci., 2000, 55, (15), 2931-2944. A one-dimensional unsteady model is formulated for biomass gasification in a stratified concurrent (downdraft) reactor. Heat and mass transfer across the bed are coupled with moisture evaporation, biomass pyrolysis, char combustion and gasification, gas-phase combustion and thermal cracking of tars. Numerical simulation has allowed to predict the influence of model parameters, kinetic constants and operational variables on process dynamics, structure of the reaction front and quality of the producer gas. In particular, two different stabilization modes of the reaction front have been determined. For high values of the air-to-fuel ratio and of the primary pyrolysis rate, the process is top-stabilized, resulting in a high conversion efficiency and good gas quality. As the air flow is decreased below a critical limit value, the reaction front becomes grate-stabilized. The two different configurations are largely determined by the gas-phase combustion of volatile pyrolysis products. Finally, the predictions of the gas composition and the axial temperature profiles are in agreement with experimental data. 03/00321 Effect of chemical pre-treatment of market wastes in biogas production Amathussalam, A., Abubacker, M.N. Asian J. Microhiol., BiorechnoL. Environ. Sci., 1999, 1, (l-2), 93-96. 32
Fuel and Energy Abstracts
January 2002
A current topic of interest in waste management is the bioconversion of cellulosic waste materials to a readily usable fuel product namely, methane (biogas). Experiments to produce methane using vegetable and fruit wastes of market in Tiruchirapalli were conducted. Wastes were mixed with cow-dung and water (w/v) and loaded into the laboratory-scale fermentors to produce methane. Biogas produced in 30 days of fermentation was 820 cm3 per 250 g of market waste with 52% methane at 35%” & 1”. Effect of various chemical pre-treatment on the market wastes revealed that sodium bicarbonate (NaHC03) enhanced biogas production to 1240 cm3 per 250 g of market waste with 57% methane in 30 days at 35” i 1” with increase in bacterial population of Closrridium buryricum and Methanobacrerium ruminatum. Anaerobic fermentation of these market waste materials with effective chemical pre-treatment can serve the dual purpose of reducing environmental pollution as well a source of renewable energy. 03/00322 Effective conversion of CO* to valuable compounds by using multi-functional catalysts Inui, T. Prepr. - Am. Chem. SW., Div. Per. Chem., 2000, 45, (I), 113117. A review with 20 references on catalyst developments in the effective reduction of COz by Hz or CHd to synthesize highly valuable major building products for the petrochemical industries. Products like ethylene, propylene, MeOH, EtOH, and high gaseous and liquid fuels such as substituted natural gas and high-octane no. gasoline partly compensate the cost of the reducing agents (Hz, CHI). 03lOO323 Energy efficient conversion of methane to syngas over NiO-MgO solid solution Choudhary, V.R., Mamman, AS. Appf. Energy, 2000.66, (2). 161-175. Methane to CO and Ha conversion reactions, involving partial oxidation by Oz, oxy-steam reforming, oxy-COz reforming, COz reforming, simultaneous steam and COz reforming, over a NiO-MgO solid solution (Ni/Mg = 0.5) have been investigated. The calcination (up to 1200°C) temperature of the catalyst has a small but significant effect on its activity/selectivity in the oxidative conversion of methane to syngas. The reduction (by Ha) temperature of the catalyst has no significant effect on the catalyst’s performance. The catalyst shows high activity and selectivity in the oxy-steam reforming and oxy-COz reforming reactions, at SOO-850°C and high space velocity [(4050) x lo3 cm3 g-’ h-l]. These two processes involve coupling of the exothermic oxidative conversion and endothermic steam or CO2 reforming reactions, making both the processes highly energy efficient and also safe to operate. The catalyst also shows high methane conversion activity (nearly 95% conversion) with 100% selectivity for both CO and Hz in the simultaneous steam and CO2 reforming of methane at (800-850°C) at a high space velocity (3.6 x lo3 cm3 g- h-i). 03/00324 Equilibrium modeling of gasification: a free energy minimization approach and its application to a circulating fluidized bed coal gasifier Li, X. et al. Fuel, 2001, 80, (2), 195-207. A non-stoichimetric equilibrium model based on free energy minimization is developed to predict the performance of gasifiers. The model considers five elements and 44 species in both the gas and solid phases. The gas composition and heating values vary primarily, with temperature and the relative abundance of key elements, especially carbon, hydrogen and oxygen. Pressure only influences the result significantly over a limited temperature range. The model predicts the onset of formation of solid carbon where the gas composition becomes insensitive to additional carbon. The carbon formation boundary is plotted in C-H-O ternary diagrams as a function of temperature and pressure. When the experimental carbon conversion is introduced, the kinetically modified equilibrium model gives good predictions of the gas composition from an air-blown pressurized circulating fluidized bed gasifier for two coals. The role of water, including both fuel moisture and steam injection, is examined based on a water balance on the feed and product gas to evaluate the steam demand. 02/00325 Evaluation of the effectiveness of the preliminary auto thermal conversion of methane for use in power plants Kundo, N.N. et al. Khim. Inreresnkh Ustoich. Razvir., 1998, 6, (5-6), 431-438. (In Russian) The overall efficiency of methane-fuelled power plants is increased by 4-11% by using partial oxidation with air (O&0.7:1 O-CH,,) and expansion of the gas in a turbine which drives a generator. The exhaust gas is then used as fuel in a regular steam power generation unit. 02/00326 Examination of gasification characteristics of pressurized two-stage entrained flow coal gasifier (comparison of basic performance with 2 T/D and 200 T/D coal gasifier) Hara, S. et al. Nippon Kikai Gukkai Ronhunshu, B-hen, 2000, 66, (644), 1198-1204. (In Japanese)
Fuel and Energy Abstracts
January 2002
A current topic of interest in waste management is the bioconversion of cellulosic waste materials to a readily usable fuel product namely, methane (biogas). Experiments to produce methane using vegetable and fruit wastes of market in Tiruchirapalli were conducted. Wastes were mixed with cow-dung and water (w/v) and loaded into the laboratory-scale fermentors to produce methane. Biogas produced in 30 days of fermentation was 820 cm3 per 250 g of market waste with 52% methane at 35%” & 1”. Effect of various chemical pre-treatment on the market wastes revealed that sodium bicarbonate (NaHC03) enhanced biogas production to 1240 cm3 per 250 g of market waste with 57% methane in 30 days at 35” i 1” with increase in bacterial population of Closrridium buryricum and Methanobacrerium ruminatum. Anaerobic fermentation of these market waste materials with effective chemical pre-treatment can serve the dual purpose of reducing environmental pollution as well a source of renewable energy. 03/00322 Effective conversion of CO* to valuable compounds by using multi-functional catalysts Inui, T. Prepr. - Am. Chem. SW., Div. Per. Chem., 2000, 45, (I), 113117. A review with 20 references on catalyst developments in the effective reduction of COz by Hz or CHd to synthesize highly valuable major building products for the petrochemical industries. Products like ethylene, propylene, MeOH, EtOH, and high gaseous and liquid fuels such as substituted natural gas and high-octane no. gasoline partly compensate the cost of the reducing agents (Hz, CHI). 03lOO323 Energy efficient conversion of methane to syngas over NiO-MgO solid solution Choudhary, V.R., Mamman, AS. Appf. Energy, 2000.66, (2). 161-175. Methane to CO and Ha conversion reactions, involving partial oxidation by Oz, oxy-steam reforming, oxy-COz reforming, COz reforming, simultaneous steam and COz reforming, over a NiO-MgO solid solution (Ni/Mg = 0.5) have been investigated. The calcination (up to 1200°C) temperature of the catalyst has a small but significant effect on its activity/selectivity in the oxidative conversion of methane to syngas. The reduction (by Ha) temperature of the catalyst has no significant effect on the catalyst’s performance. The catalyst shows high activity and selectivity in the oxy-steam reforming and oxy-COz reforming reactions, at SOO-850°C and high space velocity [(4050) x lo3 cm3 g-’ h-l]. These two processes involve coupling of the exothermic oxidative conversion and endothermic steam or CO2 reforming reactions, making both the processes highly energy efficient and also safe to operate. The catalyst also shows high methane conversion activity (nearly 95% conversion) with 100% selectivity for both CO and Hz in the simultaneous steam and CO2 reforming of methane at (800-850°C) at a high space velocity (3.6 x lo3 cm3 g- h-i). 03/00324 Equilibrium modeling of gasification: a free energy minimization approach and its application to a circulating fluidized bed coal gasifier Li, X. et al. Fuel, 2001, 80, (2), 195-207. A non-stoichimetric equilibrium model based on free energy minimization is developed to predict the performance of gasifiers. The model considers five elements and 44 species in both the gas and solid phases. The gas composition and heating values vary primarily, with temperature and the relative abundance of key elements, especially carbon, hydrogen and oxygen. Pressure only influences the result significantly over a limited temperature range. The model predicts the onset of formation of solid carbon where the gas composition becomes insensitive to additional carbon. The carbon formation boundary is plotted in C-H-O ternary diagrams as a function of temperature and pressure. When the experimental carbon conversion is introduced, the kinetically modified equilibrium model gives good predictions of the gas composition from an air-blown pressurized circulating fluidized bed gasifier for two coals. The role of water, including both fuel moisture and steam injection, is examined based on a water balance on the feed and product gas to evaluate the steam demand. 02/00325 Evaluation of the effectiveness of the preliminary auto thermal conversion of methane for use in power plants Kundo, N.N. et al. Khim. Inreresnkh Ustoich. Razvir., 1998, 6, (5-6), 431-438. (In Russian) The overall efficiency of methane-fuelled power plants is increased by 4-11% by using partial oxidation with air (O&0.7:1 O-CH,,) and expansion of the gas in a turbine which drives a generator. The exhaust gas is then used as fuel in a regular steam power generation unit. 02/00326 Examination of gasification characteristics of pressurized two-stage entrained flow coal gasifier (comparison of basic performance with 2 T/D and 200 T/D coal gasifier) Hara, S. et al. Nippon Kikai Gukkai Ronhunshu, B-hen, 2000, 66, (644), 1198-1204. (In Japanese)