Ash-related issues during combustion and gasification

Ash-related issues during combustion and gasification

04 By-products related to fuels 02lO9399 Ash-related gasification Benson, S.A., Sondreal, Cornbust.. (Proc. issues during combustion E.A. Eng. Fo...

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04 By-products

related to fuels

02lO9399 Ash-related gasification Benson, S.A., Sondreal, Cornbust..


issues during combustion E.A.

Eng. Found.

Impacl Miner. Impurities Conf. Miner. Matter Fuelsj,

and Solid Fuel 1991, l-21.

Edited by Gupta, R.P., Wall, T.F., Baxter, L. In a review with many references the effect of ash on the performance of combustion and gasification systems is described. These properties depended on the inorganic composition of the fuel and on the operating conditions. Ash caused the decrease of efficiency, unscheduled outages, equipment failures, and high cleaning costs. The detrimental effects of fuel-associated inorganic components on the combuster or the gasification process performance included slagtapping problems, fireside ash deposition, corrosion and erosion of system parts, producing fine particulates that were difficult to collect, blinding of filter media, formation of hazardous air pollutants, and production of precursors to the formation of secondary fine particulates. The variability in the chemical and physical properties were a major problem in burning and gasifying fuels in an environmentally acceptable manner. For coal there were complex problems associated with the presence or absence of major, minor, and trace elements that determined the rank of the coal. For the prediction of the ash behaviour different analytical methods were developed. 02lOO400 Carbon adsorbents from brown coal tar Pokonova, Y.V. Perspekl. Mater, 1999, 6, 102-106. (In Russian) Various carbon adsorbents with high adsorption energy (5 26 kJ/mol) and capacity with respect to argon, xenon, and other gases higher than the common adsorbents by a factor of two to three are produced from brown coal tar. The carbon adsorbents can be used in various ecological systems and shielding of nuclear reactors. 02lOO401 Carbon adsorbents from brown-coal tar containing coal Pokonova, Y.V. Khim. Tverd. Top/. fMoscow), 2000, 2, 4245. (In Russian) Microporous granular carbon adsorbents with high energy of adsorption (125.4 kJ/mol) were obtained from charge containing copolycondensate of brown-coal tar and coal additive by conventional method. According to certain indicators sorption ability of the carbon adsorbent exceeded that of industrial sorbent. 02/00402 Catalytic conversion of biomass pyrolysis vapors with zinc oxide Nokkosmaki, MI. et al. J. Arm/. Appl., 2000, 55, (l), 119-131. Conversion of pyrolysis vapours of pine sawdust was studied in micro and benach scales with zinc oxide catalyst. Three different zinc oxides were screened in a gas chromatograph system using an injection port as a fixed-bed catalytic converter in order to find appropriate reaction conditions by emphasizing a high yield of bio-oil. Catalytically treated pyrolysis oils were produced in a side stream of an atmosphere fluidized bed pyrolyser (1 kg h-i) at the catalyst temperature of 400°C. The oils with silicon carbide treatment and without any catalyst were used as references. The aim was to study the catalytic effect of zinc oxide on the composition and on the stability of the oil. The pyrolysis liquids produced were homogeneous one-phase oils. The ZnO proved to be a mild catalyst and the liquid yields were not substantially reduced. It had no effect on the water-insoluble fraction (ligninderived), but it decomposed the di-Et either-insoluble fraction (watersoluble anhydrosugars and polysaccharides). Some indications of catalyst deactivation were observed. The oil samples were aged thermally and the variation of viscosity and water content were determined. The increase in the viscosity was significantly lower for the ZnO-treated oil (55%) than for the reference oil without any catalyst (129%). The results indicated an improvement in the stability of the ZnO-treated oil.

Four commercially available coal tar pitches have been characterized through the combination of conventional techniques used for pitch characterization, like elemental analysis and solvent fractionation, and infrared spectroscopy (FTIR) and thermal analysis (thermogravimetry (TG)-differential thermal analysis (DTA)). The results obtained from this set of experiments provide suitable information to establish differences between the materials according to their industrial origin and preparation method. The differences found are a consequence of the distinct chemical composition of the pitches (determined by FTIR), as well as the dissimilar chemical interaction that exists between the molecules of different fractions of the patent pitch (evidenced from DTA). These observations are responsible for the clear differences found between a given pitch and its respective insolubles, and affect their applications, i.e. in the area of carbon fibre preparation. 02lOO405 CO2 mitigation and fuel production Steinberg, M. Prepr. - Am. chemical Sot.. Div. Pet. chemical, 2000, 45, (l), 74-76. The Carnol Process to convert COz from coal burning power plants to methanol is described. 02/00406 Coal ash utilization technology for civil industry Kozasa, K. et al. Sekitan Riyo Gijutsu Kaigi Koenshu, 1999, 9, 202-2 13. (In Japanese) A review with seven references is given on utilization of coal ash for preparation of air bubble mixing-treated soil and amendment of highwater content soil. 02/00407 Compositions of filter-vessel and cyclone ‘ash’ from pressurized fluidized bed combustion Seshadri, K.S., Smith, D.H. Energy Fuels, 2000, 14, (3), 526-532. Excessively hard filter cakes have occurred during filtration of fine particles from hot gases in pressurized fluidized bed combustion (PFBC) power plants in which dolomitic limestone was used as the SO, sorbent. These deposits forced premature plant shutdown and became a major barrier to successful development of the filtration technology. Our previous work implicated MgzCa (Sob)) as a chief cause of these excessive cake strengths, but no analytical technique was available to quantitatively relate filter-cake physical properties and operating problems to MgsCa (S04)s concentrations. Hence, a new Fourier transform IR spectroscopy technique has been developed to analyse for MgzCa (SO4)s in the presence of CaS04 and other compounds in PFBC samples. This technique was used to measure ‘chemical compositions of various samples taken from either the cyclone or the hot-gas filtration vessel of a PEBC demonstration power plant. These measurements clarify and further demonstrate the critical role played by MgzCa (SO&. Further measurements of the type described here should allow researchers to quantitatively determine how MgsCa (S04)s concentrations in filter cakes depend on various operating parameters (e.g. temperatures, pressures, and composition of the coal and sorbent), and thus solve problems that have prevented the successful development of hot-gas filtration for PFBC power plants. 02/00406 Comprehensive utilization of the solid wastes from coal in China Zhang, W., Song, H. REWAS ‘99-Global Symp. Recycl., Waste Treatomic Clean Technol., Proc., 1999, 1, 635-641. Edited by Gaballah I., Hager J., Solozabal R. In China coal constitutes 75.1% as primary energy source, representing twice that of world average Coal production in China is 1 billion tons/ year. Solid wastes gangues are >lOO million tons. This accumulated gangues over the years have reached 3 billion tons, and cover ~110 million mz land. For example, in Shanxi province there are 124 large gangue dumps. Development and exploitation of gangues in China implies both a great environmental improvement and social and economic benefits. This work shows some applications of recovering gangues in different fields: (1) power generation, (2) gas production, (3) manufacturing chemical products, and (4) recovering products to manufacture cement, fertilizers, building materials, etc.

02lOO403 Catalytic performance and carbon deposition behavior of a nio-mgo solid solution in methane reforming with carbon dioxide under pressurized conditions Tomishige, K. er al. Ind. Eng. Chem. Res., 2000, 39, (6), 1891-1897. The activity and carbon deposition behaviour were investigated on the catalyst for CO1 reforming of methane under pressurized conditions. A NiO.osMgO.p,O solid solution catalyst with low surface area (~4 m’lg) exhibited a lower carbon formation rate than other NiO-MgO solid solution and MgO-supported Pt catalysts. This decrease in carbon formation rate was attributed to the suppression of Ni aggregation. The effect of such additives as Sn, Ge, and Ca to a Nir,OsMg,,p,O solid solution was investigated. Sn was an effective component for decreasing the carbon deposition, which is especially formed by methane decomposition.

02lOO409 Convert flyash into usable high-margin products Giovando, C. Power, 2000, 144, (2), 65-66, 68. A jet mill comminution process removes the carbon in flyash to yield low- and high-carbon products. A one-step process separates unburned carbon from flyash to produce a final carbon content of c3-4% loss on ignition. A carbon product with loss on ignition 70-80% can be used as absorbent carbon, metallurgical grade carbon or fuel supplement. Shaped building products are obtained from coal ash.

02/00404 Characterisation of coal tar pitches by thermal analysis, infrared spectroscopy and solvent fractionation Alcatiiz-Monge, J. er al. Fuel, 2001, 80, (l), 41-48.

02lOO410 Detection of HNCO during the Low-Temperature Combustion of Coal Chars Nicholls, P.M., Nelson, P.F. Energy Fuels, 2000, 14, (4), 943-944.


Fuel and Energy Abstracts

January 2002