fuels (derived gaseous
oxygen) in these power plants are also discussed, together with coal combined power plants with carbon monoxide conversion and absorptive carbon dioxide scrubbing, fundamentals for calculation and analysis of combined-cycle power plants with integrated coal gasification, and carbon dioxide retention.
The air blown gasification cycle 9aio2Q39 Dawes, S. G. et al. Inst. Chem. Eng. Symp. Ser., 1997, 143, 91-103. An increase of up to five-fold in global primary energy demand is projected by the year 2100 and coal is expected to account for 30% of this for the foreseeable future. Clean coal technologies (CCT) are thus being developed since they promise higher thermal efficiencies, lower electricity costs and improved environmental performance when compared with existing technologies. The Air Blown Gasification Cycle (ABGC) is an example of a gasification combined cycle CCT. The ABGC is a hybrid partial gasification cycle based an a novel, air blown pressurized fluidized bed gasifier (PFBG) coupled to a circulating fluidized bed combustor (CFBC) to burn residual char from the PFBG. Fuel gas from the PFBG is cleaned and burned to produce a gas at high temperature and pressure which is expanded through can be reused for the wastewater treatment. The system attained targets for the emission limits for activated-coke regeneration. Arc plasma reactor and method for coal gasification 98lQ2Q40 Karpenko, E. I. et al. Russ. RU 2,087,525 (Cl. ClOJ3/18), 20 Aug 1997, Appl. 94,011,507, 5 Apr 1994. From Izobreteniya 1997, (23), 271. (In Russian) Black liquor recovery by pressurized, 98102041 blown gasification
Lorson, H. et al. TappiJ., 1997, 80, (12), 111-116. The advantages over the Tomlinson recovery boiler technology offered by pressurized, oxygen-blown, entrained-flow gasification technology for black liquor recovery include better process flexibility and performance. The technology should function in black liquor service for both mill de-bottlenecking and large scale recovery projects. Applications for the mediumBTU gas produced are: a fuel for firing in gas turbines and power boilers or as a synthesis gas for chemical production. The paper provides a brief discussion of the development and features of a pressurized, oxygen-blown, entrained-flow gasification technology, descriptions of some alternative schemes for employing the technology in black liquor service and an economic assessment of mill retrofit alternatives.
Broadened pulse-step change-isotopic sharp pulse analysis of the mechanism of methane partlal oxidation to synthesis gas
Hu, Y. H. and Ruckenstein, E. J. Physical Chemical B, 1998, 102, (1). 230233. Transient response analysis of a broadened pulse, combined with either a step change or a sharp isotopic pulse, was used to study the mechanism of the partial oxidation of methane. Over the unreduced NiOiSiOz catalyst, the reaction between methane and oxygen occurs via the Eley-Rideal mechanism: methane in the gas phase reacting with oxygen in the adsorbed state. However, the reaction takes place over the reduced NiO/SiOz catalyst by a Langmuir-Hinshelwood mechanism: methane and oxygen reacting in the adsorbed states. In addition, isotopic pulses of “02 revealed that over the reduced catalyst lattice oxygen is formed and reduced by the carbon species; hence, a dynamic redox process occurs on the reduced catalyst.
Catalyst for converting methanol Into synthesis gas 98102043 Klabunovskij, E. 1. et al. Russ. RU 2,087,190 (Cl. BOlJ23/76), 20 Aug 1997, Appl. 95,118,488, 30 Ott 1995. From Izobreteniya 1997, (23). 185. (In Russian) Catalytic gasification of coal for the production of fuel cell feedstock TimDe.R. C. et al. Int. J. Hvdronen Enemv, 1997, 22, (5), 487-492. gal02044
Cat&y&c gasification of low:ra& coal yiaded hydrogkn and methane as fuels for fuel cells. Bench-scale steam gasification catalyst testing was carried out on Illinois No. 6 bituminous and North Dakota lignite coals with catalysts containing iron, nickel, calcium or potassium, and some combinations of these. In the case of both coals, all of the catalysts tested showed a modest catalytic effect, ranging from negligible to a nearly 30-fold increase in the rate of the reaction. Nickel and iron enhanced the rate slightly, while increasing methane concentration. The lignite had a 15-35 times higher catalytic semi-coke-steam gasification rate than the bituminous coal. CO hydrogenation over nanometer spinel-type Co/ Mn complex oxides prepared by sol-gel method
Liang, Q. et al. Appl. Catal., A, 1998, 166, (l), 191-199. The sol-gel method was used to prepare nanometer spinel-type Co/Mn oxides with different Co/Mn atmosphere ratios, single phase composition and large specific surface area. The formation process, structure and catalytic properties of these Co/Mn oxides were studied by XRD, TEM, FTIR, TPR, XPS and CO hydrogenation reaction tests. The complete formation temperature of nanometer spinel-type Cos_,Mn,Od (0 5 x 5 1.4) particles by sol-gel method was 350°C much lower than that by using nitrate decomposition method or solid-state reaction method. CO hydrogenation reactions tests indicated that the nanometer Co/Mn oxide catalysts
Fuel and Energy Abstracts
had much higher selectivity to light olefins and a lower catalytic activity and methane formation than the corresponding co-precipitated catalysts with the same composition. The catalytic properties were also susceptible to the effects of different heat treatments of the nanometer CoiMn oxide catalyst. With the increase of the calcination temperature, the catalytic activity decreased, while the selectivity of light olefins increased. For nanometer spinel-type COj_, Mn,Od (0 < x 5 1.4) catalysts with different Co/Mn ratios, with the increase of the Mn content, both the catalytic activity and methane formation were decreased, but the light olefins formation was enhanced.
Co-gasification of biomass and coal in a pressurized fluidlzed bed gasifler
Andries, J. and Hein, K. R. G. Dev. Thermochem. Biomass Cowers., 1997, 2, 900-906. Edited by Bridgwater, A. V. and Boocock, D. G. B., Blackie, London, UK. A three year experimental and theoretical research project will be carried out to investigate the co-gasification of biomass and coal in a pressurized fluidized bed gasifier. Delft University of Technology will determine experimentally the influence of feedstock and operating conditions on the characteristics of the gasifier. Pelletized straw and Miscanthus will be used as biomass feedstock. Experimental studies, using state of the art, laboratory scale methods will be executed by other partners in the project to detect the extent and the origins of synergistic effects and to provide background data for the assessment of the experimental results obtained from the Delft test rig. Besides the assessment of the time-averaged properties of the fuel gas, the time-dependent characteristics will be determined. The results will be compared with the acceptability range provided by, another partner, Nuovo Pignone. The results of this evaluation will be used to implement and test an optimized control strategy for operating the pressurized fluidized bed gasifier. The objectives of the project, the test rig to be used and the time schedule of the project are all described in detail.
Coal gasification apparatus, coal gasification method and integrated coal gasification combined-cycle power generation system
Morihara, A. et al. PCT Int. Appl. WO 97 44,412 (Cl. ClOJ3/46), 27 Nov 1997, JP Appl. 96/124,396, 20 May 1996, 38 pp. (In Japanese) The construction of this coal gasification apparatus means that a gasification furnace and a heat recovery unit for recovering heat obtained by a coal gasifying reaction in the coal gasification furnace without imposing load on subsequent equipment are integrally provided in a single vessel. The heat recovery unit is provided immediately above the gasification furnace and composed of heating tubes extending perpendicularly to a generated gas flow, and the gasification furnace is composed of a lower furnace portion and an upper furnace portion. An upper stage nozzle is disposed in the upper furnace portion and a lower stage nozzle is disposed in the lower furnace portion. The lower furnace portion supplies coal and a large amount of oxidizer via the lower stage nozzle to provide a temperature sufficient to melt the ash, and the upper furnace portion supplies coal and a small amount of oxidizer via the upper stage nozzle to provide a temperature insufficient to melt the ash, whereby the deposition of the ash content on furnace walls and the heat recovery unit is prevented. Also, the heating tubes constituting the heat recovery unit, are composed of two stages, which are different in surface temperature from each other, whereby the generated gas can be efficiently decreased in temperature to ease influences on constituent materials of the subsequent equipment.
98/0204a Development of coking-resistant Ni-based catalyst for partial oxidation and CO*-reforming of methane to syngas Chen, P. et al. Appl. Catal., A, 1998, 166, (2). 343-350. A small amount of trivalent-metal oxides, Cr203 and LaZOj was added to a Ni-Mg-0 catalyst for the partial oxidation of methane and the CO*reforming of methane reactions. With this addition, an improvement in the performance of the catalyst for coking-resistance has been observed.
Effect of fluorine on the gasification rate of liquid boron oxide droplets
Yetter, R. A. et al. Combustion and Flame, 1998, 112, (3). 387-403. The chemically facilitated gasification of a liquid boron oxide droplet in high temperature environments has been simulated with a recently developed model. It includes a detailed gas-phase reaction mechanism, separate steps for the adsorption and desorption of gas-phase species at the surface and multicomponent molecular diffusion. Gasification rate prediction are presented for droplets of different diameter and environments with different temperature and composition. The effect of fluorine on the gasification rate is of particular interest. Model calculations are also analysed with reaction flux and gradient sensitivity analyses to determine the fastest and rate controlling steps of the gasification process. Fluorine addition is shown to accelerate the gasification process. The degree of enhancement was found to depend upon the temperature and mixture composition of the surrounding gas and the diameter of the droplet.