The effects of pressure on coal reactions during pulverised coal combustion and gastification

The effects of pressure on coal reactions during pulverised coal combustion and gastification

01 03/00467 Geochemical features of hazardous elements and cleaning potential of coal from Xinzhouyao Coal Mine Wang, W.-F. et al. Zhongguo Kuangye Da...

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01 03/00467 Geochemical features of hazardous elements and cleaning potential of coal from Xinzhouyao Coal Mine Wang, W.-F. et al. Zhongguo Kuangye Daxue Xuehao, 2002, 3 I, (3). 28 l-284. (In Chinese) Based on the analysis and test of 41 elements, the occurrence, mechanism and environmental effect of 19 potentially hazardous elements in samples of coal seam 9 from the Xinzhouyao Coal Mine were discussed. The results show that the hazardous elements S, As, Sb, Se, Co, MO, Pb, Ni, Br, Mn and Be are notably enriched in the seam, and As, Sb, Se, Co, Pb and Ni tend to increase toward the seam roof. The occurrence of As, Sb, Se, MO, Co and inorganic S is mainly related to pyrite, most of which may be removed through physical washing methods. The Br occurs in organic matter and is hard to remove. Organic S has a high content and is potentially hazardous to the environment, so should be removed before use. The potentially hazardous elements in coal seam 9 might be derived from the superposition of the various geochemical origins in which the paracontemporaneous origin might play a leading role. 03/00468 Grey clustering prediction for slagging potential of coal blends combustion Qiu, J. et al. Combustion Science and Technolog~~, 2002. 114, (3), 5 l-70. The ash behaviour and slagging characteristics of several individual coals, different in rank and ash content, and of their two-component blends, were studied by measuring chemical composition, ash fusion temperature, viscosity, and mineral transformation. The experimental results indicate that ash fusion temperatures for various percentages of two different coal blends illustr&e non-arithmetic aieraeiner The fusion slag of base coals affects the viscosity of coa”l vblends. Temperature and atmosphere affect mineral species vaporization. Considering the limitation of single slagging index for prediction, an overall grey clustering model that takes into account the main related parameters such as ash characteristics, mineral transformation, and combustion parameters is proposed to predict the slagging propensity of the blends. The results suggest that the slagging propensity of coal blends from two coals of similar reactivity and slagging potential was similar to that of the individual coals. However, when one coal was blended with another coal with widely different reactivity or slagging potential, the slagging grade of the coal blends changed significantly. The results of slagging experiments in a combustion test furnace were in agreement with those from model prediction. It implies that the proposed overall grey clustering model can predict slagging tendency more accurately than conventional index. Moreover, the predicted results are comparable with that from a practical boiler slagging test. Preliminary study of tectono-thermal evolution 03/00469 characteristics and coalbed methane resource in Huainan coalfield Li, X. el ul. Kuangw Xuehao. 2002, 22, (I), 85-91. (In Chinese) This paper studies tectono-thermal evolution characteristics and coalbed methane resource in the Huainan coalfield by fission track analysis. The results show that: (1) at least three thermal events have occurred since late Paleozoic at ~240 140 and 80 Ma, respectively; (2) paleo-geothermal gradient was higher than that at the present. The study estimated that denudation thickness of the area was >2000 m. On the basis of the characteristics of tectono-thermal evolution of the Huainan coalfield, the preliminary conclusions will be drawn as follows: the first and second tectono-thermal events happened at 240-140 Ma during the Mesozoic, so that most of the coal formed in late Paleozoic was gradually metamorphosed into gaseous one and a minor amount of it into fat coal. Production of coalbed methane was not too much, and the tectono-thermal events in the late Cretaceous led to the release of coalbed methane into the atmosphere. In general, more gas will release from the regions where structures are better developed than that from the regions lacking structures, which may be suitable for the development of coalbed methane. This method may be applicable to coalbed methane exploration and development. Product analysis of catalytic multi-stage hydro03/00470 pyrolysis of coal Li, W. et al. Zhongguo Kuongw Dcluuc Xuehao, 2002, 3 1, (3). 246-25 I. (In Chinese) Multi-stage hydropyrolysis (MHyPy) and hydropyrolysis (HyPy) of Xundian lignite, with MO& as the catalyst, were performed in a fixed bed reactor. The product distribution and property were investigated in detail. The results show that the tar yield increases to 63.9% during MHyPy compared with that of 51.8% in HyPy, while the gas yield decreases by a half. The tar composition does not make big difference between MHyPy and HyPy. However, the light aromatics in the tar from MHyPy increase remarkably by 42%, 37.8% and 115.4% for BTX, PCX and naphthalenes respectively. The specific surface area of char from MHyPy is larger than that from HyPy. The average pore diameter of char from MHyPy is smaller than that from HyPy, while the pore volume increases by 100% compared with that from HyPy. The catalytic MHyPy has an obvious advantage over HyPy.

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Relationship between coal powder and its 03/00471 combustibility Xie, J-L. et al. Journal of Wuhan Universit,, of Tecirnolo,g.v, Matuials Science Edition, 2002, 17, (l), 72-75. Coal’s volatile component, ash and fixed carbon content have different functions in different stages of a combustion process, but the traditional coal classification can precisely show its combustion property. In this experiment coal’s evaluation indexes (ignition index D,, burn off index Df) were used to quality show the ignition property and combustion ending property of coal samples. Meanwhile, considering actual heating circumstances in calciner (in cement plants), this study established the relation among the ignition index, burn off index and coal’s industrial analysis value, which makes it possible for the user to predict the quality of coal before using. 03/00472 Spontaneous ignition of brown coal dust. Experiment, determination of kinetic parameters, and mathematical modeling Amel’chugov, S. P. et ul. Fiziko Goreni1.o I I ‘zrl w. 3003, 38, (3). 48-54. (In Russian) An apparatus and a study of self-ignition and explosion of brown coal dust are described. The kinetic parameters (activation energy and preexponential factor) for Irsha-Borodino brown coal were detected. It was shown that at certain coal/oxidant ratios a two-stage explosion is observed. The repeated explosion is due to the thermal activation of coal at the first stage of explosion. Mathematical models describing spontaneous ignition of brown coal dust were developed. Status and prospects of the use of Ukrainian salty 03/00473 coal in power generation. Review Dunaevs’ka, N. I. et al. Ekotekhrzologii i Re.\l~r\otber lc~:iwtzic~. 2002. (3), 29-33. (In Ukrainian) The estimated salty coal deposits of Bogdanovsk, Novomoskovsk, and Petrikovsk are in the range of 10 billion tons. The characteristics of this bituminous coal are suitable for use in thermal powj,:r plants. 03/00474 The effect of coal type in dry-sorbent/coal injection for control of SOa and NO, emissions Levendis, Y. A, and Ergut, A. Proceedings of the International Technical Conference on Coal Utilization & Fuel ‘Y.l.\trmj, 2002, 2, (27), 875-885. (In Japanese) Simultaneous reduction of NO,, SO?, and particulate emissions from power plants is achieved by a method combining injection of sorbent/ coal blends with a ceramic honeycomb filter. The filter is mounted in an elevated temperature region where it retains sorbent particles for prolonged periods of time and facilitates their utilization until it is eventually regenerated (cleaned). This filter also captures and oxidizes particulate C, which otherwise might contribute to the formation of air toxics, e.g. dioxins, as the effluent cools further Performance of composite sorbents, such as CaC03 and NaHCO;. and the porous sorbent calcium formate was evaluated in the laboratory. Sorbent powders were blended with three types of pulverized coal to achieve NO, reduction, i.e. bituminous, sub-bituminous, anti lignite. Sorbent/ coal blends were injected in a simulated effluent gas containing SO2 and NO at a gas temperature of 1150” (1423 K), upstream from a ceramic filter, which was maintained at 600 (X73 KI. The molar Ca:S ratio was -2, and the fuel:air equivalence ratio. (.>,was also ~2 (fuelrich) for all tests. Emphasis was placed on differentiating the effect of coal type on reducing SO2 and NO, emission concentrations. Results showed SOZ removal efficiency of 35-80% was achieved, depending on coal type and sorbent used. NO, reduction efficiency of 45-55% was obtained, depending on coal type. Particulate removal efficiency by the filter was measured at 97-99%. The effects of pressure on coal reactions during 03/00475 pulverised coal combustion and gasification Wall, T. F. et al. Progress in Energy und Comhustiol? s’(icww. 2002, 28, (5), 405-433. Advanced clean coal technologies, e.g. power generation from integrated gasification combined cycle (IGCC) and pressurized fluidized bed combustor, have attracted increased Interest from the scientific and technological communities over the last few decades. Pressures up to 40 atm have been applied to these technologies, which inherently result in an increase in coal throughput, a reduction in pollutant emissions and an enhancement in the intr:n5ity of reaction. Therefore, fundamental understanding of the eftect of operating pressure on coal reactions is essential to the development of these technologies. In this paper, the pressure effect on a variety of aspects of coal reactions reported in the open literature has been reviewed. Major emphasis of the paper is given to experimental observations, although some theoretical modelling is reviewed. The pressure has been found to significantly influence the volatiles yield and coal swelling during devolatilization, hence the structure and morphology of the char generated. More char particles of high porosity are formed at higher pressures. Char structure appears to play a significant role in burnout Fuel and Energy Abstracts

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0 1 Solid fuels (preparation) of residual char and ash formation. In general, at higher pressures, coal particles burn quicker and form finer ash particles. Increasing reactant pressure enhances char combustion and gasification reaction rate, which can be understood by an adsorption-desorption mechanism. These factors have been applied to the understanding of a practical high-pressure gasifier. Most of the work published has been at the lower temperatures (typically
Preparation 03/00477 Biodesulfurization of coal in stirred reactor. Kinetic models Cara, J. et al. Zngenieria Quimica (Madrid, Spuin), 2002, 34, (386), 231242. (In Spanish) Biodesulfurization of coal using Thiobacillus ferroxidans was studied in stirred reactors to detect reaction kinetics. The specific biodesulfurization velocity is dependent on initial inoculum and on coal type treated and was 0.299 day-‘. 03/00478 Coal drying improves performance and reduces emissions Bullinger, C. et al. Proceedings qf’ the International Technical Conference on Coal Utilization & Fuel Systems, 2002, 2, (27), 639-650. Lignite and subbituminous coals from the western USA are attractive fuels for power plants due their low cost and emissions; however, lignite and PRB coals typically contain high amounts of moisture and/ or ash. When high moisture coals are burned in utility boilers, ~7% of the fuel heat input is used to evaporate fuel moisture. This results in higher fuel flow, higher stack flue gas flow, higher parasitic power, lower plant efficiency, and higher mill maintenance costs vs. lowmoisture coal. Efforts are underway in Europe and Australia to develop efficient coal dewatering and drying processes. Thermal drying and dewatering and mechanical dewatering are used. Thermal processes typically used depend on a high-grade heat to evaporate or remove moisture from coal. Field test results, conducted with dried lignite coal at a 550 MW unit in North Dakota, and a coal drying process that uses a low-grade waste heat to evaporate a portion of fuel moisture from the lignite feedstock, are presented. Process layout, coal drying equipment, and fuel moisture impact, on plant performance and emissions are discussed. Improved boiler and unit performance, achieved during this test by removing 6% of fuel moisture was in 2.6-2.8%. This performance improvement was primarily due to a reduction in moisture evaporation loss, lower stack loss, and decrease in auxiliary power requirements. Assuming a capacity factor of 0.8, this 6% reduction in fuel moisture represents annual savings of $1.3 million for both units at the Coal Creek Station, North Dakota. If implemented on all US lignite and PRB units, it would represent annual savings of 134

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$19 million for lignite-fired plants, and $90 million for PRB-tired plants. Field test results were for 6.1% moisture reduction. Future work will include test burns with lower moisture content to detect the impact on boiler operations. This will also make it possible to detect the optimal coal moisture content. 03/00479 Deep cleaning of coal-derived fuel gases at high temperature in the ultra-clean process Slimane, R. B. et al. Proceedings of the International Technical Corzference on Coal Utilization & Fuel S\,stems, 2002. 2, (27). 1033. 1044. The Siemens Westinghouse Power Corporation and the gas Technological Institute are developing an innovative process for hot syngas cleanup, the ‘Ultra-Clean Process’, to meet the needs of advanced IGCC-based co-production of electrical power and chemical or fuel products. This process has two cleanup stages integrated in series and relies on the injection of dry sulfur and halide sorbent fines to accomplish contaminant removal to parts-per-billion levels. This paper reports on the work GTI recently completed to identify and evaluate suitable materials for each stage, their feed rates, and the operating temperature for each stage to satisfy the gas cleaning requirements. 03/00480 Desulfurization of peroxyacid treated Indonesian coals by organic base Ishak, M. A. M. et (11.ACGC Chemical Research Cornmunic,ution,v, 2002, 14, 14-25. Combustion of high sulfur coals is one of the fundamental reasons for problems with sulfur dioxide emissions. In order for high and medium sulfur coals to be utilized as clean fuel, the desulfurization techniques have to effectively remove both the inorganic and organic sulfur forms. Subsequent reaction on the mildly oxidized peroxyacetic acid treated Banjarmasin Haji Ali-Aliansar and Banjarmasin A coals with sodium benzoxide, which is a strong organic base, showed a further organic sulfur removal in both coals of approximately 46% and 30% respectively. The additional organic sulfur removal by the organic base strengthen the assumption that the C-S bonds have been broken due to the weakening of the bonds during the pretreatment oxidation by the formation of sulfones, sulfoxides and sulfonic acid from the divalent sulfur species that are present in the coals. The effect of organic base treatment on the pretreated coals showed that the coals micro-structures were not severely affected, as revealed by scanning electron microscope with energy dispersive X-ray (SEM-EDX). 03/00481 Detailed characterization of heteroatomcontaining molecules in light distillates derived from Tanito Harum coal and its hydrotreated oil Sumbogo Murti, S. D. et ul. Fuel, 2002, 81, (17), 2241-2248. Heteroatom-containing compounds in as-prepared and hydrotreated distillates produced from Tanito Harum coal were identified by the aid of gas chromatography with atomic emission detector (GC-AED) which can detect all the elements (C, H, N, S, 0) contained in the molecules. Alkylated benzothiophenes and dibenzothiophenes were found to be the major sulfur compounds in the original fraction, all of them being completely removed by the hydrotreatment at 350°C 10 MPa, and 60 min. Alkylated anilines, quinoline, indoles, and carbazoles were found in the original oil as nitrogen compounds. Two specific nitrogen compounds survived through the hydrotreatment, being identified as CllHzoN and Ci4H2sN, respectively, according to the calibrated elemental ratios by GC-AED and molecular weights measured by GC-MS (mass spectrometry). Such empirical formulae were quite similar to CiiHigN and C14H23N, respectively, which were detected by high MS and NMR after the concentration by extraction. Some sulfur compounds were observed in the non-aromatic fraction, while all the nitrogen compounds were completely concentrated in the aromatic fraction by the conventional column chromatographic separation. It is also noted that alkylated phenols, benzofurans and dibenzofurans were found as typical oxygen compounds in the distillate. Thus, GC-AED can identify the hetero-atom containing compounds based on the simultaneous multi-element analysis. 03/00482 Fluorine mineralisation from burning coal spoilheaps in the Russian Urals Sokol, E. V. et al. Mineralogy und Petrology, 2002, 75, (l-2), 23-40. Anhydrous iron, aluminum and fluorine-rich paralavas were found in the burned spoil-heaps of the Chelyabinsk coal basin, Russia. The rocks contain tridymite, anorthite, ferroan fluorine-bearing cordierite, fluorine-bearing mullite, periclase, fluorapatite, micas of the F-biotiteF-phlogopite series, fluortopaz, fluorite, and sellaite. The fluorine-rich minerals formed as a result of local thermal reactions of sedimentary carbonates and silicates with gaseous fluorine. During coal combustion fluorine concentrates in the annealed ankeritic marls where the increase of F is hundreds of times over its concentration in the initial sedimentary rocks. The formation of MgF:! and CaF2 promotes local melting at relatively low temperatures (T < 1OOO’C) with the residuum consisting of two immiscible liquids. One crystallizes as fluorides, the