02961 Vaporization of alkali and trace metal impurities in coal gasification and combustion systems

02961 Vaporization of alkali and trace metal impurities in coal gasification and combustion systems

01 terms of surface effects and by reference Laplace-Young Furthermore, this equation has been used to quantify phenomena. equation. dewatering 9910...

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01 terms of surface effects and by reference Laplace-Young Furthermore, this equation has been used to quantify phenomena.

equation. dewatering

99102957 Study on the formation mechanism of doubledensity fluidized beds Wei, L. Zhongnan Gongye Daxue Xuebao, 1998, 29, (4), 330-333. (In Chinese) An experimental and theoretical study was performed on the formation mechanism of double-density fluidized beds. The force exerted on fluidized particles and the functions of the pyramidal part were analysed. It is found that the special structure of fluidized bed strengthens the segregation between two types of particles. In addition, the proper gas velocity can homogenize the density in the same separating area. Therefore, a doubledensity fluidized bed which meets the technical needs of coal preparation is formed. Temperature programmed combustion studies of 99102958 the co-processing of coal and waste materials Ndaji, F. E. et al. Fuel, 1999, 68, (3), 301-307. Considering the need to minimize the environmental impact of sewage sludge disposal, waste materials disposal by incineration is becoming increasingly important. Temperature-programmed combustion (TPC) was employed to study the interaction between coal, polyethylene and dried sewage sludge, which are possible components in coal/waste materials coprocessing combustion systems. The TPC studies were carried out on the raw materials and 1:l mixtures of sludge/coal and sludge/polyethylene. Comparison of the gas evolution profiles of the mixtures with corresponding profiles obtained by the summation of the profiles of the component materials indicate that there were interactions between the mixtures during the combustion. Significant interactions may occur when the combustion temperature ranges of the materials overlap. 99102959 Trace element reductions in fine coal using advanced physical cleaning Mohanty, M. K. et al. Coal Prep., 1998, 19, (3-4), 195-211. Studies have shown that trace element contents of a given coal can be substantially reduced by pre-combustion physical cleaning. More specifically, using an advanced fine coal cleaning circuit comprised of an enhanced gravity separator (EGS) and a flotation column, over 80% of the mercury and selenium contents of a -250 pm Illinois no. 6 coal sample were rejected while achieving an energy recovery of 80%. This performance was achieved due to a strong affinity of the mercury and selenium with the ash forming and coal pyrite particles (which were rejected at rates of 84% and 83%, respectively). However, chromium’s rejection rate was only 62%; this is likely to be because it was found to have only a moderate affinity with the organic material. Additional reduction in total sulfur and trace element contents is provided by treatment of the pre-cleaned pulverized coal combustion boiler feed sample. Overall, the EGS-Column circuit was found to be effective in reducing the amounts of three trace elements found in coal that have been identified as potential air toxics when emitted into the air during the coal combustion process. 99102960 Use of waste metal oxides for dry scrubbing with barrier filters Zievers, J. F. et al. High Temp. Gas Clean., [Pap. Int. Symp. Exhib. Gas Clean. High Temp.], 3rd, 1996,291-301. Edited by Schmidt, E., Institut fuer Mechanische Verfahrenstechnik und Mechanik der Universitaet Karlsruhe, Karlsruhe, Germany Coal processing in the USA has to meet both Clean Air Act mandates and New Source Performance Standards (NSPS) for particulate, SO2 and NO emissions. Until technology is developed to meet the legislative requirements both effectively and economically the large coal reserves found in the USA will remain unusable. Recent breakthroughs in particulate control, specifically ceramic filtration technology, have shown that NSPS limits on particulates can be achieved at high process temperatures, thereby minimizing thermal losses and system complexity. A further avenue explored by many researchers is the use of metal oxide sorbents, particularly those of zinc, tin and iron oxide, which have resulted in promising SO1 emission reduction levels. A cost-effective alternative to traditional calcium-based sorbents or metal oxide sorbents for the removal of sulfur in hot gas streams is to use spent metal oxide materials, such as those generated by steel manufacturing and smelting processes. In this paper ongoing research into spent metal oxides in discussed and the findings of many projects are presented. Vaporization of alkali and trace metal impurities in 99102961 coal gasification and combustion systems Krishnan, G. N. et al. High Temp. Gas Clean., [Pap. In?. Symp. Exhib. Gas Clean. High Temp.], 3, 1996, 651-663. Edited by Schmidt, E., Institut fuer Mechanische Verfabrenstechnik und Mechanik der Universitaet Karlsruhe (TH), Karlsruhe, Germany Measurement techniques for vapour species from coal gasification are evaluated. The gaseous impurities, including alkali and trace metal vapours, generated by coal gasification are harmful to several components of integrated gasification combined cycle systems including particle filters and gas turbines. In this work two mass spectrometry techniques were used to identify and measure sub-ppm concentrations of alkali and other inorganic species. At temperatures of 1070-1220 K, vapour phase sodium species (Na,

Solid fuels (economics,

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NazO, NaCl, NazSO,,) concentrations were co.05 ppm under excess air combustion conditions; however, under gasification conditions, sodium vapour species were present at -14 ppm at a temperature of 1100 K. Results prove a mass spectrometer can measure trace-level vapour species in a high temperature gas produced by coal combustion or gasification. This technique provides unambiguous identification and measurement of important vapour species without interference from entrained particles (fume and fly ash) and can readily be adapted to monitor high-temperature gas streams.

Transport,

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99102962 Method for development of a forecasting model for gas outbursts hazard in mines of Chelyabinsk basin Lapin, E. S. and Lyadskii, A. V. Izv. Vyssh. Uchebn. Zaved., Corn. Zh., 1998, (5-6), 12-18. (In Russian) Based on both coal and coal bed characteristics, the propensity of coal beds for gas outbursts in mines of Chelyabinsk basin has been predicted.

Economics,

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Economic decision making for methane drainage 99102963 systems for underground coal mines Wang, A. and Mutmansky, J. M. Min. Eng., 1998,50, (3) 69-74. Defined in this work are the elements of a basic economic model for decision making when considering a methane drainage system for an underground coal mine. A drainage system entails significant capital and operating expense; hence the decision to utilize drainage must be made carefully. The model outlines the basic structure of decision making and considers the costs and benefits when the methane is marketed and when the methane is vented to the atmosphere. The effects on mine safety and the dust levels in the mine are also considered, both in a general format and as economic variables. 99102964 Environmental impact assessment and management in the mining industry Sinding, K. Natural Resources Forum, 1999, 23, (l), 57-63. Significant environmental problems have always plagued the mineral industries. In many cases, dealing with them is technically possible, but the cost is often prohibitive in an industry with uniform products and much trade. A possible solution, is to make mineral products less uniform and more distinguishable in terms of the environmental impacts involved in producing a specific shipment or volume of mineral; this could be combined with a means to identify each shipment. Such action would require identification techniques and, more particularly, clear and unequivocal evidence regarding environmental impacts at all stages of production. Global environmental problems and clean coal 99102965 technology Kawaguchi, Y. Sekitan Riyo Gijutsu Kaigi Koenshu, 1998, 8, 1-19. (In Japanese) Japan’s energy supply and coal utilization conditions, development and applications of clean coal technologies are addressed, including improving combustion efficiency, desulfurization and denitrogenation, multipurpose coal conversion and coal ash usage. International co-operation and technology transfer for clean coal technology are also described. 99102966 International cooperation activities on coal utilization Takeda, Y. Sekitan Riyo Gijutsu Kaigi Koenshu, 1998, 8, 20-25. (In Japanese) This review focuses on international co-operation activities at the Center for Coal Utilization on environment-friendly coal utilization technologies. These include fuel gas desulfurization, recirculating fluidized bed boilers, briquette manufacturing, desulfurized coal-water mixture production and integrated technical systems, in countries such as China, Thailand, India and Pakistan. 99102967 Standardized quality indexes for coal products under new conditions of raw-material coking resources in Russia Ol’shanetskii, L. G. Kok.~Khim., 1998, (8) 2-9. (In Russian) Some of the less economically viable mines in the Kuznetsk Basin, which is the basic resource (75%,) of coking coals, are facing closure. This paper discusses the effect of substitution of valuable coking coal resources with other coals. Switching to new technologies of coke manufacturing and increasing the use of open-pit mined coals are proposed. Due to the new situation in the coal and coking industries, the author considers the issues of improvement of quality parameters in coal production and, in particular, new propositions were made regarding correlations based on moisture and ash and also characterization of oxidability, classification and technological value.

Fuel and Energy Abstracts

September

1999

315