Showing papers on "Coal published in 1980"
TL;DR: The physical and chemical properties of coal ashes are dependent on the coal's geological origin, combustion condition, efficiency of particulate removal, and degree of weathering before final disposal as discussed by the authors.
Abstract: Impacts of land-oriented utilization and disposal of various coal combustion residues are summarized. The physical and chemical properties of coal ashes are dependent on the coal's geological origin, combustion condition, efficiency of particulate removal, and degree of weathering before final disposal. Coal residues, applied on cropland, are not practical sources of essential plant nutrients N, P, and K; however, they can effectively serve as a supplementary supply of Ca, S, B, Mo, and Se to soils. Fly ash could also be an effective amendment in neutralizing soil acidity. Many of the observed chemical and biological effects of fly ash applications to soils resulted from the increased activities of Ca/sup 2 +/ and OH/sup -/ ions. Most unweathered fly ashes, especially those coming from the subbituminous and lignite coals of the western US, are high in these constituents and usually will cause high soil salinity. The accumulation of B, Mo, Se, and soluble salts in fly ash-amended soils appear to be the most serious constraints associated with land application of fly ash to soil.
753 citations
Patent•
23 May 1980
TL;DR: In this paper, an in situ coal gasification process adapted for large scale commercial projects is provided, where techniques and standards for avoiding or controlling subsidence and for conducting gasification operations in free water laden seams and in coal seams subject to spontaneous combustion.
Abstract: An in situ coal gasification process adapted for large scale commercial projects is provided. Techniques are provided to insure establishment of a gasification front over the full seam thickness as each successive injection well in the array is brought on line. This is accomplished by controlling the oxidant introduction in a prescribed manner during the early stages of injection after pneumatic communication between well pairs has been established. Also provided are techniques and standards for avoiding or controlling subsidence and for conducting gasification operations in free water laden seams and in coal seams subject to spontaneous combustion.
260 citations
Patent•
21 Jul 1980
TL;DR: In the underground gasification of a swelling coal, the high gas-flow link between the injection and the production wells is produced by introducing hot air into the injection well at a pressure sufficient to fracture the coal.
Abstract: In the underground gasification of a swelling coal the high gas-flow link between the injection and the production wells is produced by introducing hot air into the injection well at a pressure sufficient to fracture the coal. The bulk permeability of the coal proximate to the link is increased and the plugging of the link during the subsequent in situ combustion and gasification procedure is suppressed by continuing the injection of the hot air, heated to a temperature below the softening point of the coal, into the injection well, through the link to the production well without combustion of the coal.
252 citations
01 Jan 1980
TL;DR: In this article, the authors used catalytic gasification of coal is an old technology with patents dating back to at least 1884 [1] and it was used to gasify charcoal, lignite, or subbituminous coals.
Abstract: Catalytic gasification of coal is an old technology with patents dating back to at least 1884 [1]. To gasify charcoal, lignite, or subbituminous coals, these materials were mixed with the oxides, hydroxides, or carbonates of alkali metals or alkaline-earth metals, Considerably higher gasification rates or lower gasification temperatures were realized by these additives.
201 citations
TL;DR: X-ray diffraction, Fourier transform infrared, and chemical-phase analyses were performed to determine elemental compositions of samples, and water-soluble sulfates are the predominant species present in oil-fired particulate emissions.
Abstract: A methodology for determining inorganic compounds present in particulate emissions from fossil fuel combustion processes is described Samples collected from power plants burning oil and coal fuels of different composition provided a typical range of flyashes for the investigation X-ray diffraction, Fourier transform infrared, and chemical-phase analyses were performed to determine elemental compositions of samples Water-soluble sulfates are the predominant species present in oil-fired particulate emissions (2 photos, 7 references, 9 tables)
175 citations
170 citations
TL;DR: In this paper, a comprehensive model for the simulation of fluidized bed coal combustors is developed, capable of predicting the combustion efficiency, char and limestone elutriation and the corresponding particle size distribution in the bed and in the entrained materials.
Abstract: A comprehensive model for the simulation of fluidized bed coal combustors (FBC) is developed, capable of predicting the combustion efficiency, char and limestone elutriation and the corresponding particle size distribution in the bed and in the entrained materials, solids withdrawal rate from the bed, bed temperature profile, sulfur dioxide retention, sulfur dioxide and NOx emissions, concentrations of oxygen, carbon monoxide, carbon dioxide, volatiles, sulfur dioxide and NOx along the combustor height. The model can also simulate combustors with varying cross section along the bed height. The performance of the model is compared with the data obtained from four different combustors. Agreement between the computed results and the data is good. The salient features in the model which need further investigation are pointed out.
143 citations
TL;DR: In this article, coal, activated carbon, coke and a mixture of coal and biomass were gasified using direct solar irradiation in a 23kW solar furnace located at the U.S. Army White Sands Missile Range, White Sands, New Mexico.
141 citations
TL;DR: In this article, the authors investigated the devolatilization behavior of ten bituminous coals under rapid heating conditions using a small-scale fluidized-bed pyrolyser.
132 citations
TL;DR: In this paper, a coal extract was analyzed by combined gas chromatography-mass spectrometry using glass capillary columns and a sulfur specific flame photometric detection was used to identify the sulfur-containing aromatic compounds.
130 citations
TL;DR: In this paper, the influence of cations on the pyrolysis behavior of brown coals under flash heating conditions was investigated by means of a small fluidized-bed Pyrolyser.
TL;DR: In this paper, the ratio of the thicknesses of a layer of peat and the coal bed formed from that peat has been calculated for a bituminous coal bed in central Utah.
Abstract: The ratio of the thicknesses of a layer of peat and the coal bed formed from that peat has been calculated for a bituminous coal bed in central Utah. The method used involves comparison of the thickness of peat eroded by a laterally migrating channel system with the thickness of coal now absent from the outcrop. The peat:coal thickness ratio calculated by this method is approximately 11:1.
TL;DR: In this article, the specific heat, enthalpy, and entropy of coal, char, tar, and ash as a function of temperature and material composition are presented. But the standard entropy for coal is approximated by comparing the behavior of the standard entropies of a number of aliphatic and aromatic hydrocarbons.
TL;DR: The effects of pollutants from the coal industry on the macroinvertebrate fauna of a small river in the South Wales coalfield were investigated during 1972 and 1973 as discussed by the authors.
Abstract: SUMMARY. The effects of pollutants from the coal industry on the macroinvertebrate fauna of a small river in the South Wales coalfield were investigated during 1972 and 1973.
Three major types of pollution, each spatially separate, affected the river and its tributaries. The upper reaches received acidic drainage from coal stockpiles. The lower reaches received a discharge from a drift mine, bearing high loads of suspended coal particles which caused siltation of the river bed downstream to its confluence with the R. Taff (3.5 km). The largest tributary was subjected, under neutral pH, to siltation by ferric hydroxide, derived from seepage from an abandoned mine.
In the upper reaches, a few acid-tolerant invertebrate species survived in low numbers. Downstream recovery was not complete before the discharge of coal particles. In the reaches silted by ferric hydroxide or coal there was a pronounced reduction (80–90%) in faunal abundance. Clear differences in sensitivity of invertebrate groups to these types of siltation were apparent.
The data are used to assess the various methods of biological surveillance involving invertebrates.
TL;DR: The 309 organic compounds reported in the literature as emissions from selected combustion processes are tabulated, with 109 originating from coal combustion, 213 from waste incineration and 69 from coal/refuse combustion as mentioned in this paper.
20 May 1980
TL;DR: In this paper, the results from the Hoe Creek No. 3 underground coal gasification test are described, where the experiment employed a drilled channel between process wells spaced 130' apart.
Abstract: A major objective of the US Energy Program is the development of processes to produce clean fuels from coal. Underground coal gasification is one of the most promising of these processes. If successful, underground coal gasification (UCG) would quadruple the proven reserves of the US coal. Cost for products produced from UCG are projected to be 65 to 75% of those from conventional coal conversion. Finally, UCG appears to possess environmental advantages since no mining is involved and there are less solid wastes produced. In this paper we describe results from the Hoe Creek No. 3 underground coal gasification test. The experiment employed a drilled channel between process wells spaced 130' apart. The drilled channel was enlarged by reverse combustion prior to forward gasification. The first week of forward gasification was carried out using air injection, during which 250 tons of coal were consumed yielding an average dry product gas heating value of 114 Btu/scf. Following this phase, steam and oxygen were injected (generally a 50-50 mixture) for 47 days, during which 3945 tons of coal were consumed at an average rate of 84 tons of coal per day and an average dry gas heating value of 217 Btu/scf. Themore » average gas composition during the steam-oxygen phase was 37% H/sub 2/, 5% CH/sub 4/, 11% CO, and 44% CO/sub 2/. Gas recovery was approximately 82% during the test, and the average thermochemical efficiency was near 65%.« less
TL;DR: In this article, coal and fly ash were analyzed for major ash elements by fusing with lithium tetraborate in an automatic fusion device, the Claisse Fluxer.
Abstract: The coal sample is first ashed with high temperature ashing or with RF plasma low temperature ashing. The coal ash or fly ash can be analyzed for major ash elements by fusing with lithium tetraborate in an automatic fusion device, the Claisse Fluxer. The ash samples are also dissolved in a Parr bomb in a mixture of aqua regia and HF. Subsequently, the solutions are analyzed for eight major (Al, Ca, Fe, K, Mg, Na, Si, and Ti) and 20 trace elements (As, B, Ba, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Sr, U, V, and Zn) by inductively coupled plasma emission spectroscopy. Mercury in coal and fly ash is determined on a separate aliquot by the cold vapor atomic absorption technique. Fluorine and chlorine in the samples are determined by fusing with Na/sub 2/CO/sub 3/ and Eschka mixture, respectively, and then measuring the two ions in solution with specific ion electrodes. Oxygen in the samples can be determined rapidly and nondestructively by 14-MeV neutron activation analysis. These methods have been tested by analyzing several NBS coal and fly ash standards with good accuracy and reproducibility. 10 tables.
TL;DR: In this paper, a ternary diffusion and viscous flow model was used to predict the concentration profiles for gases and tar in coal pyrolysis, showing that at low pressures, product yields depend on particle size only, while at high pressures they depend on pressure and particle size.
Abstract: Intraparticle mass transfer in coal pyrolysis is described by ternary diffusion and viscous flow, in conjunction with a simple pore model to predict concentration profiles for gases and tar. At low pressures, product yields depend on particle size only, while at high pressures they depend on pressure and particle size. Limited experimental data from a subbituminous coal confirm these trends. Data from a bituminous coal show different trends, as expected from the drastic changes the pore structure undergoes during pyrolysis.
TL;DR: The catalytic coal gasification (CCG) as discussed by the authors was developed for the production of substitute natural gas (SNG) from bituminous coal in the early 1970s by the Exxon Research and Engineering Company.
Abstract: Exxon Research and Engineering Company is engaged in research and development on catalytic coal gasification (CCG) for the production of substitute natural gas (SNG). the catalysts being studied are the basic and weak acid salts of potassium. the use of a gasification catalyst allows the gasifier temperature to be reduced, reduces the tendency for swelling and agglomeration of caking coals and promotes gas phase methanation equilibrium. These features of the catalyst are utilized in a novel processing sequence which involves separation of product gas into methane (SNG) and a CO/H2 stream which is recycled to the gasifier. the predevelopment phase of research on this process concept was completed in early 1978 and included bench-scale research on catalyst recovery and kinetics, the operation of a 6 in diameter × 30 ft long fluid bed gasifier and supporting engineering studies.
As part of the engineering programme, a conceptual design has been developed for a pioneer commercial CCG plant producing SNG from Illinois No. 6 bituminous coal. the paper reviews the status of research and development on the CCG programme and describes the conceptual design and economics for the commercial scale CCG plant.
TL;DR: In this article, the processes of coal liquefaction and co-carbonization of coal/pitch blends in terms of physical and chemical properties of the fluid phases found in both pyrolysis systems are outlined.
TL;DR: In this paper, the concentration of 51 elements in the recently issued NBS bituminous coal (SRM 1632a) and 43 elements in Subbituminous Coal ( SRM 1635) have been measured mainly with the use of instrumental neutron activation analysis and neutron-capture prompt gamma-ray activation analysis.
Abstract: Concentrations of 51 elements in the recently issued NBS bituminous Coal (SRM 1632a) and 43 elements in Subbituminous Coal (SRM 1635) have been measured mainly with the use of instrumental neutron activation analysis and neutron-capture prompt ..gamma..-ray activation analysis. The results are in good agreement with values reported for some of the elements in the standards by NBS. Concentration values for many elements in addition to those given by NBS are presented for comparison with results that may be obtained by other laboratories. 4 talbes.
TL;DR: A number of adsorbed polycyclic aromatic hydrocarbons will spontaneously oxidize in the absence of light, with those compounds containing a benzylic carbon being particularly susceptible.
Abstract: Polycyclic aromatic hydrocarbons adsorbed onto coal fly ash were found to be stabilized against photochemical decomposition. However, a number of adsorbed polycyclic aromatic hydrocarbons will spontaneously oxidize in the absence of light, with those compounds containing a benzylic carbon being particularly susceptible. The decomposition rate appears to be fly ash-dependent.
Journal Article•
TL;DR: In this article, the authors pointed out that bord-and-pillar mining is the most important method of coal extraction in South American underground coal mines, and advocates that pillar design procedures should be refined to make more rational allowance for the differences in strength properties between various coal seams and roof and floor strata.
Abstract: The paper points out that bord-and-pillar mining is the most important method of coal extraction in South Af~ican underground coal mines, and advocates that pillar design procedures should be refined to make more rational allowance for the differences in strength properties between various coal seams and roof and floor strata. However, any deviations from well-established design procedures must be based on sound engineering principles and reliable data on the strength properties of the seams and strata concerned. Recent information indicates that practices for the protection of surface structures against underground mining should be revised.
TL;DR: In this article, the pyrolysis phase cannot be treated separately from the hydropyrolyse phase, and three key process variables, hydrogen pressure, temperature, and particle diameter, are seen to have major effects on the total yields of products.
Patent•
28 Jul 1980
TL;DR: An integrated process for the gasification of coal alone or with other carbon-containing materials such as solid municipal wastes, biomass and sewage sludges, wherein the endothermic heat required by a gasification reaction is supplied at least in a significant part by the exothermic reaction of CaO in the form of calcined lime or dolomite with carbon dioxide is presented in this article.
Abstract: An integrated process for the gasification of coal alone or with other carbon-containing materials such as solid municipal wastes, biomass and sewage sludges, wherein the endothermic heat required by the gasification reaction is supplied at least in a significant part by the exothermic reaction of CaO in the form of calcined lime or dolomite with carbon dioxide The CO 2 is recycled to provide a high CO 2 vapor pressure for the exothermic reaction The calcium carbonate formed in the reaction is decomposed in a combustor to produce the CaO which is recycled to the gasification stage
TL;DR: In this paper, a method was presented of evaluating the kinetic parameters for the ignition reaction of coal based on the Semenov's thermal ignition theory adopted to coal particle ignition, which was made by comparing the measured induction periods for the coal particles with those calculated numerically.
TL;DR: In this article, the maximum degree of benzene and tetralin-induced swelling occurred in a coal of 75 wt% carbon content and the size and/or flexibility of the chain segments between crosslinks in coal are at a maximum.