Showing papers on "Coal published in 1983"
TL;DR: In this paper, a demineralized lignite has been used in a fundamental study of the role of carbon active sites in coal char gasification, where the chars were prepared in N 2 under a wide variety of conditions of heating rate (10 K min −1 to 10 4 K s −1 ), temperature (975 − 1475 K) and residence time (0.3 s-1 h).
452 citations
TL;DR: In this article, a series of peat and coal samples ranging in rank between the stages of brown coal and high-volatile bituminous A coal were studied for the relationships between vitrinite reflectance, fluorescence properties of different liptinite macerals and of huminite/vitrinite and results of elemental analyses and of the Rock-Eval pyrolysis.
327 citations
Patent•
01 Aug 1983
TL;DR: In this paper, a liquid solvent stream and a gaseous hydrogen stream are introduced into the fractured coal formation, allowing reaction and conversion of the coal to lighter, hydrogenated components.
Abstract: In-situ hydrogenation of an underground coal formation is carried out by fracturing the formation and sealing it, to provide an in-situ reactor site. Then a liquid solvent stream and a gaseous hydrogen stream are introduced into the fractured formation, allowing reaction and conversion of the coal to lighter, hydrogenated components.
274 citations
TL;DR: In this article, a new explanation for the endothermic reactions below 650 °C reported by previous workers is proposed as a consequence of the unexpectedly high specific heat predicted in this region using the above model.
209 citations
TL;DR: In this paper, an oxygen functional group analysis was performed to determine the carboxylic acid, hydroxyl and ether group content of the coal before, during and after the reaction.
200 citations
TL;DR: In this paper, a model of the chemical changes during thermal decomposition of coal is presented, which describes the kinetics of the release of the main volatile matter constituents, thereby permitting the changes in the mass and composition of the solid residue to be estimated by element balances.
198 citations
TL;DR: In this article, the use of X-ray photoelectron spectroscopy to probe the chemistry of coal surfaces is reviewed and its application to the functional group composition of bulk coals is discussed.
185 citations
TL;DR: In this article, the flotation behavior of a series of coals is described in terms of the predominant oxygen-containing functional groups, and the maximum flotation response occurs close to the isoelectric point of the demineralized coal.
184 citations
TL;DR: An integrated chemical/microbiological investigation is described, directed toward identifying the nature of direct-acting mutagens found in extracts of diesel and ambient POM, as well as those formed upon exposure of environmentally relevant PAH to simulated natural and polluted atmospheres.
Abstract: The growing use of coal for heating and electric power generation and diesel engines in light duty motor vehicles will increase not only the existing atmospheric concentrations of criteria pollutan...
174 citations
TL;DR: The pattern of sulfur transformation in peat across the Everglades basin indicates that pyrite formation in organic-rich swamps depends on the use of organic oxysulfur compounds in dissimilatory respiration by sulfur-reducing bacteria.
Abstract: The pattern of sulfur transformation in peat across the Everglades basin indicates that pyrite formation in organic-rich swamps depends on the use of organic oxysulfur compounds in dissimilatory respiration by sulfur-reducing bacteria. This paragenesis explains the primary distribution of sulfur compounds in low-sulfur coals and possibly in most coals and many organic-rich soils and sediments. It also accounts for the occurrence of framboidal pyrite bound in fossil tissue in coal and sediments.
TL;DR: In this article, basic features of the reaction kinetics of potassium-catalysed coal gasification and how small-scale data were used for the conceptual design of large fluidized-bed gasifiers are discussed.
TL;DR: In this paper, a study was made of the gasification behavior of coal chars doped with small amounts of alkali metal carbonates, and the kinetic data were consistent with catalytic mechanisms involving oxidation/reduction cycles on the char substrates.
TL;DR: The effect of traces of sulphur in the gas stream on catalysis of gasification or carbon-forming reactions by calcium, potassium, or sodium is not well understood at present as discussed by the authors.
TL;DR: In this paper, the generation of carbon fines by attrition during the fluidized combustion of a bituminous coal was studied by means of a 140mm ID fluidized-bed combustor under variable excess air factor, bed temperature, fluidizing velocity and size of bed sand and coal.
Abstract: The generation of carbon fines by attrition during the fluidized combustion of a bituminous coal has been studied by means of a 140mm ID fluidized-bed combustor under variable excess air factor, bed temperature, fluidizing velocity and size of bed sand and coal. Results indicate that rates of attrited fines are roughly proportional to excess of gas velocity above the minimum for fluidization and bed carbon exposed surface. Attrition rate constant is affected by size of sand and, to a less extent, and particularly with finer coal, by bed temperature.
TL;DR: The value of currently used bioassays for the evaluation of the role of trace metal compounds, either as major biologically active components or as modifiers of biological effects of organic compounds is assessed and some problems related to the application and interpretation of short-termBioassays are considered.
Abstract: Metallic elements contained in coal, oil and gasoline are mobilized by combustion processes and may be emitted into the atmosphere, mainly as components of submicron particles. The information abou...
TL;DR: In this paper, the mechanism and the rate of flame propagation through dust clouds of carbon, coal, aluminium and magnesium have been investigated and the results show that the burning velocity is influenced by particle size, fuel transfer number, dust concentration, volatile matter (for coal), oxygen enrichment and heat loss by radiation from the burning fuel particles.
Abstract: The mechanism and the rate of flame propagation through dust clouds of carbon, coal, aluminium and magnesium have been investigated. Any errors due to the upward buoyant motion of burnt gases and the downward settling velocity of dust particles were eliminated by conducting these experiments in a zero-gravity environment. A technique of flat-flame propagation was developed to measure the burning velocity accurately. The results show that the burning velocity is influenced by particle size, fuel transfer number, dust concentration, volatile matter (for coal), oxygen enrichment and heat loss by radiation from the burning fuel particles. A simple model to elucidate the structure and the mechanism of flame propagation is developed. Then expressions to predict the flame thickness and the burning velocity are derived. Attention is drawn to the similarity that exists between the mechanisms of flame propagation through dust clouds and through fuel mists. The importance of radiation heat loss is emphasized. It is shown that for a dust cloud of particle size 10 μ m of graphite or aluminium in oxygen, radiation loss from particles can reduce the burning velocity by as much as 40% or 25% respectively.
TL;DR: In this article, a new formula for calculating the calorific value of coal from its ultimate analysis has been obtained by regression analysis of a data bank consisting of data on 775 samples of U.S. coals of all ranks.
TL;DR: In this paper, the authors investigated the role of physico-chemical factors that control the adsorption of dextrin by coal and found that the more hydrophobic demineralized coal was found to exhibit an adaption density twice the adsoption density of natural coal.
TL;DR: In this paper, a reflection on the gasification-kinetics of alkali-doped coal was carried out and the catalytic activities of Li, Na, K, Cs were compared.
Journal Article•
TL;DR: In this article, the first stage, berl-saddle-packed anaerobic filter resulted in very limited reductions in DOC, COD, and specific organic compounds monitored, and the removal efficiencies of DOC and COD were realized in the completely mixed, expanded-bed granular activated carbon filter.
Abstract: Coal gasification has been regarded as a promising technology for the production of the gaseous fuels needed to supplement dwindling reserves of petroleum and natural gas. The organic constituents of coal gasification wastewater are 60 to 80% phenols. The first-stage, berl-saddle-packed anaerobic filter resulted in very limited reductions in DOC, COD, and the specific organic compounds monitored. Excellent removal efficiencies of DOC, COD, and the specific organic compounds were realized in the completely mixed, expanded-bed anaerobic granular activated carbon filter. The activated carbon offers a larger sheltered microbial attachment area than does the berl-saddle plastic medium. The success of the activated carbon packed filter is probably due to surface adsorption. Some of the mass of the retained COD may represent the fraction of the feed constitutents that is nonbiodegradable in and inhibitory to the anaerobic environment. 11 figures, 4 tables. (DP)
TL;DR: In this article, a review of mineral matter of German hard coal, its reactions with catalysts during gasification with steam to form new crystalline phases are dealt with by means of microscopy, XRD, XRF and microprobe analysis.
TL;DR: In this article, it was shown that coal pyrolysis rates are insensitive to rank over a wide range of conditions and that coal rank is a minor cause for these differences which must be attributed to the effects of heat and mass transfer and to the assumptions used in deriving a kinetic rate.
TL;DR: In this article, the fine structure associated with phenols and ethers in coal pyrolysis liquids has been characterized and the contributions to the liquid pyrolysates of the phenolic functional groups already existing in coal have been separated from the contributions of these same same groups generated by ether cleavage during the pyroglysis.
TL;DR: Nickel catalyst exhibited an extremely high activity in the gasification of some low rank coals at a temperature as low as 750 K as discussed by the authors, and approximately 85% of Yallourn coal was converted within 30 min in steam at 773 K. But hydrogen sulphide was strongly adsorbed on the nickel catalyst and retarded this reaction.
TL;DR: Sorption data have been obtained for a range of vapours on a Kentucky No.12 coal and the results indicate that surface areas obtained in this way are influenced by vapour-induced swelling effects as discussed by the authors.
TL;DR: In this paper, an unreactive hvC bituminous coal has been hydrogenated in a batch-stirred reactor using pyrite, hydrogen sulphide, and Pyrite+hydrogen sulphide as catalysts.
Book•
01 Jan 1983
TL;DR: In this article, the utility of electron spin resonance (ESR) studies of coal-free radicals in the study of coal hydroliquefaction has been investigated in the context of coal and coal conversion.
Abstract: If one understands and controls free radical chemistry, one could then design much more efficient synthetic fuels This book attempts to ascertain the importance of this thesis by examining the available evidence from electron spin resonance (ESR) studies of coal-free radicals Proceeding from elementary concepts to the more specialized topics, it is based primarily on the work done by the authors in their systematic investigation of the utility of ESR in the study of coal-free radicals and their relevance to coal hydroliquefaction Although dealing with coal and coal conversion, the book is also applicable to the conversion of other fossil fuels
Patent•
07 Jul 1983TL;DR: In this article, a carbonaceous material, such as crushed coal, is impregnated with an inexpensive alkali metal compound such as sodium chloride, and then pretreated with a stream containing steam at a temperature of 350° to 650° C. to enhance the catalytic activity of the mixture in subsequent gasification.
Abstract: A carbonaceous material, such as crushed coal, is admixed or impregnated with an inexpensive alkali metal compound, such as sodium chloride, and then pretreated with a stream containing steam at a temperature of 350° to 650° C. to enhance the catalytic activity of the mixture in a subsequent gasification of the mixture. The treatment may result in the transformation of the alkali metal compound into another, more catalytically active, form.
TL;DR: In this paper, the results of core drilling of near surface seams near Wakefield NSW have provided high volatile bituminous coal samples that have been subject to varying degrees of natural in situ oxidation.