Showing papers on "Coal published in 1978"

Coal mine ground control

Abstract: Mine Layouts and Ground Control Practices in Underground Coal Mines Common Ground Control Problems in Underground Coal Mines Rock Properties and in situ Stresses Geological Effects and Roof Stability Classification and Investigation Roof Bolting Coal Pillars Ground Control in Longwall Mining Ground Control in Multiple-Seam Mining Bumps Instrumentation Special Supports and Problems Surface Subsidence Appendixes.

Coal gasification method

Abstract: A method for underground gasification of coal or brown coal, in which a substantially uniform gasification or combustion front is maintained by filling the cavity generated by gasification of coal with a filler so as to drive said front in an upward direction through the coal layer, the gases for maintaining the gasification being introduced through a first borehole and the combustion gases being discharged through a second borehole, one of these boreholes being used for introducing the filler, said boreholes extending at an inclination corresponding to the general inclination of the coal layer, and preferably converging towards one another.

Process for in situ coal gasification

Abstract: In situ coal gasification to form a methane rich gas is carried out by injecting a lower aliphatic alcohol such as methanol into a coal seam, raising the temperature to cause dissociation of the alcohol and injecting water into the same. Nascent hydrogen is produced which reacts with the coal to form methane. The product gas may also contain hydrogen and carbon monoxide which can be separated and reacted to form methanol.

Product Composition and Kinetics of Lignite Pyrolysis

Abstract: Previous research at M.I.T. on coal pyrolysis in inert gas and in hydrogen was based on the measurement of coal weight loss, referred to as volatiles yield. The work is now being extended to include volatiles composition measurements and elemental analysis of the char for the same ranges of experimental conditions covered in the previous study. To this end, the previous apparatus has been modified to permit the collection and analysis of volatiles. This paper presents the first set of composition data, for lignite pyrolysis, and some initial interpretations of pyrolysis behavior in the light of the products formed. The pyrolysis of pulverized Montana lignite by time-resolved measurement of the yields and compositions of products formed under controlled temperature-time histories was studied in a captive sample apparatus. The yields of water, carbon monoxide, carbon dioxide, hydrogen, and hydrocarbon gases and light liquids were determined by gas chromatography. The yields of all the volatile products increase monotonically with temperature and approach asymptotic values at the higher temperatures.

Depositional Models in Coal Exploration and Mine Planning in Appalachian Region

Abstract: Geologic studies in the Appalachian region have shown that many parameters of coal beds (thickness, continuity, roof and floor rock, sulfur and trace-element content, and ash) can be attributed to the depositional environment in which the peat beds formed and to the tectonic setting at the time of deposition. With an understanding of the depositional setting of the coal seam and contemporaneous tectonic influences, the characteristics and variability of many of these parameters can be predicted. Coals formed in "back-barrier" environments tend to be thin, laterally discontinuous, high in sulfur, and to exhibit severe roof problems. Therefore, they are not generally important as minable coals. Coal beds deposited in the "lower delta-plain" environment are relatively widespread with fewer roof problems but generally are thin and show a highly irregular pattern of sulfur and trace-element distribution. Conversely, "upper delta plain-fluvial" coals are low in sulfur, are thick locally, but are commonly discontinuous laterally. Despite these problems, some "lower delta-plain" and "upper delta plain-fluvial" coals are successfully mined. However, most important seams in the Appalachian area are in the transitional zone between these two environmental facies. In this transition zone thick coals attain a relatively high degree of lateral continuity and are usually low in sulfur. Contemporaneous tectonic influences are superposed on changes in seam character attributed to variations in environments of deposition. Rapid subsidence during sedimentation generally results in abrupt variations in coal seams but favors lower sulfur and trace-element content, whereas slower subsidence favors greater lateral continuity but higher content of chemically precipitated material.

A model for moving‐bed coal gasification reactors

Abstract: A steady state model of moving-bed coal gasification reactors has been developed. Model predictions are in agreement with published commercial plant data for Lurgi pressurized gasification reactors and a pilot plant slagging gasifier. The dependence of reactor performance on operating variables has been studied for Illinois and Wyoming coals. For a given coal, maximum efficiency is determined by the coal-to-oxygen feed ratio. The location of the maximum temperature, which defines the combustion zone, is an important operating variable. Efficient operation of the dry ash reactor cannot be carried out below a critical feed gas temperature because of insufficient gasification and excessive carbon loss in the ash.

Underground coal gasification

Abstract: Underground coal gasification (UCG) is a method whereby the mining and conversion of coal are accomplished in a single step. Many field tests of UCG have been operated worldwide since the 1930's with varying degrees of success; based on this experience (especially in the USSR and US), a field design which is applicable to a wide range of geological conditions and coal properties has evolved. This review discusses the rationale of this design and provides a physicochemical interpretation for the operation of a UCG system. Pertinent field and laboratory results as well as formal mathematical models of an in-situ gasifer are evaluated as part of the analysis. 158 references.

Method of underground fuel gasification

Abstract: For mining combustible minerals a plurality of boreholes are drilled in a gasifiable seam, e.g., in a coal bed, said boreholes 1 through 4 being intercommunicated by a number of gasification ducts. Then the combustible mineral is initiated to fire, and an oxygen-containing blast gas is blown through some of said boreholes into the gasification ducts, with the result that the generator gas is formed. Simultaneously a carbon- and/or hydrogen-containing blast gas is blown through other boreholes situated along the flow of the generator gas to enrich the latter with combustible ingredients. As a result some chemical reactions proceed under the effect of heat produced by the generator gas, whereby additional amounts of combustible elements are formed which add to the calorific value of the generator gas being withdrawn. The method is instrumental also in controlling the composition of the generator gas withdrawn by varying the ratio of the components of the blast gas enriching the generator gas.

Underground linkage of wells for production of coal in situ

Abstract: In preparation for producing coal in situ two or more production wells are linked together through the coal seam by burned channels created by one or more blind hole burns.

Fuel injection staged sectoral combustor for burning low-BTU fuel gas

Abstract: A high-temperature combustor for burning low-BTU coal gas in a gas turbine is described. The combustor comprises a plurality of individual combustor chambers. Each combustor chamber has a main burning zone and a pilot burning zone. A pipe for the low-BTU coal gas is connected to the upstream end of the pilot burning zone: this pipe surrounds a liquid fuel source and is in turn surrounded by an air supply pipe: swirling means are provided between the liquid fuel source and the coal gas pipe and between the gas pipe and the air pipe. Additional preheated air is provided by counter-current coolant air in passages formed by a double wall arrangement of the walls of the main burning zone communicating with passages of a double wall arrangement of the pilot burning zone: this preheated air is turned at the upstream end of the pilot burning zone through swirlers to mix with the original gas and air input (and the liquid fuel input when used) to provide more efficient combustion. One or more fuel injection stages (second stages) are provided for direct input of coal gas into the main burning zone. The countercurrent air coolant passages are connected to swirlers surrounding the input from each second stage to provide additional oxidant.

Radiological impact of airborne effluents of coal and nuclear plants.

Abstract: Radiation doses from airborne effluents of model coal-fired and nuclear power plants (1000 megawatts electric) are compared. Assuming a 1 percent ash release to the atmosphere (Environmental Protection Agency regulation) and 1 part per million of uranium and 2 parts per million of thorium in the coal (approximately the U.S. average), population doses from the coal plant are typically higher than those from pressurized-water or boiling-water reactors that meet government regulations. Higher radionuclide contents and ash releases are common and would result in increased doses from the coal plant. The study does not assess the impact of non-radiological pollutants or the total radiological impacts of a coal versus a nuclear economy.

Laboratory measurements of ground water leaching and transport of pollutants produced during underground coal gasification

Abstract: Two series of laboratory experiments dealing with release and migration of pollutants produced during underground coal gasification are discussed. In the first series of experiments coal ash samples prepared by heat treatment to 1000, 1100, and 1200/sup 0/C have been subjected to water leaching at 23/sup 0/C. The leachate, was analyzed for concentrations of Ca, K, Al, Ba, Fe, SO/sub 4/, OH, Mg, and Na ions likely to be present. The data provide a quantitative picture of the amount and rate of release of these various elements from coal ash left underground. Furthermore, the measured concentrations of the various elements studied in the laboratory experiments are generally in good agreement with results from ground water measurements conducted at the LLL Hoe Creek 1 coal gasification site. A second set of experiments deals with transport of pollutants away from a gasification site by the natural ground water flow through the coal seam. Two idealized cases have been studied: transport of NaBr and transport of phenol. The experiments were carried out by flowing solutions of these materials through a 1.5 m packed column of coal and measuring the breakthrough curves at various points along the column. The results are analyzed using amore » simple one-dimensional transport model. The results show the strong adsorption of phenol by the coal (K/sub d/ = 40). These results are compared with recent measurements of the cocentration of phenolic material left near an underground gasifier.« less

Microbial desulfurization of coal

Abstract: A process for the removal of pyrite from coal wherein an aqueous slurry containing finely-divided coal particles is subjected to the action of iron and sulfur oxidizing microorganisms selected from the Thiobacillus ferrooxidans group in a concentration range of between about 3×10 10 and 1×10 12 cells per gram of pyrite present in the coal slurry.

Hoe Creek II field experiment on underground coal gasification, preliminary results

Abstract: A second in-situ coal gasification experiment was performed by Lawrence Livermore Laboratory at Hoe Creek in Wyoming. The Linked Vertical Wells scheme for in-situ coal gasification was used. The experiment took 100 days for air flow testing, reverse combustion linking, forward combustion gasification, and post-burn steam flow. Air was used for gasification except for a 2-day test with oxygen and steam. Reverse combustion linking took 14 days at 1.6 m/day. Air requirements for linking were 0.398 Mgmol per meter of link assuming a single direct link. The coal pyrolysed during linking was 17 m/sup 3/, which corresponds to a single link 1.0 m in diameter. There was, however, strong evidence of at least two linkage paths. The detected links stayed below the 3 m level in the 7.6 coal seam; however, the product flow from the forward-burn gasification probably followed the coal-overburden interface not the reverse burn channels at the 3 m level. A total of 232 Mgmols (194 Mscf) of gas was produced with heating value above 125 kJ/mol (140 Btu/scf) for significant time periods and an average of 96 kJ/mol (108 Btu/scf). During the oxygen-steam test the heating value was above 270 kJ/gmol (300 Btu/scf) twice and averagedmore » 235 kJ/gmol (265 Btu/scf). The coal recovery was 1310 m/sup 3/ (1950 ton). Gasification was terminated because of decreasing product quality not because of burn through. The product quality decreased because of increasing underground heat loss.« less

Use of tracers in laboratory and field tests of underground coal gasification and oil shale retorting. [35 references]

Abstract: Tracers have recently been suggested for laboratory and field experiments of simulated and actual underground retorting of coal and oil shale The intended use of laboratory and field retort testing is examined and found to be mainly for estimation of properties of the flow field The field implementation, data reduction procedure and preliminary results of helium tracer work at Hoe Creek II coal gasification experiment are presented It was found that the active void volume calculated from the tracer data generally agrees with the consumed coal volume determined from material balances One and two-dimensional dispersion models predict a highly dispersive system This review of tracer theory and its usual laboratory application has served to point out its limitations and proper usage The usage of tracer theory in laboratory and field tests of UCG and oil shale retorting was found to include: generation of information on the flow properties; determination of the total amount of active void volume; determination of the dispersiveness of the injected gas; and analysis of flow channeling and fissuring At this time lack of knowledge of the flow field needed for interpreting the tracer experiments makes the analysis difficult In order to understand the tracer data, amore » theory involving the solution of an inverse problem needs to be developed« less

Ground-water and subsidence investigations of the LLL in situ coal gasification experiments. [Hoe Creek No. 1; Hoe Creek No. 2]

Abstract: Ground-water sampling and subsidence measurements have been carried out at the sites of two in situ coal gasification experiments conducted in northeastern Wyoming by the Lawrence Livermore Laboratory. Changes in ground-water quality and the possible effects of subsidence and ground movement induced by the gasification cavity represent important environmental concerns associated with the in situ coal gasification process. Our ground-water quality measurements near the site of the first experiment (Hoe Creek I) show a continuing decrease, after more than a year, in the concentration of important contaminants such as phenolic materials. Laboratory measurements have provided detailed information concerning phenol adsorption by coal. Long-term effects due to ground-water flow, and the detailed behavior of other contaminants remain to be investigated. Data from subsurface geotechnical instruments installed at the second gasification experiment (Hoe Creek II), as well as measurements of ground-water levels indicate that roof collapse has connected the gasification cavity with overlying aquifers. The implications of this interconnection for the dispersal of underground contaminants are being investigated.

Control aspects of underground coal gasification: LLL investigations of ground-water and subsidence effects. [Hoe Creek I and II]

Abstract: Our investigations are designed to evaluate some of the environmental implications of in situ coal gasification, and to identify appropriate environmental controls. Changes in ground-water quality and the possible effects of subsidence and ground movement induced by the underground gasification cavity represent significant environmental concerns associated with the in situ gasification process. We have measured these effects at the site of two in situ coal gasification experiments conducted in northeastern Wyoming by the Lawrence Livermore Laboratory. Our measurements of ground-water quality in the vicinity of the gasification experiments indicate that the reaction products, such as ash and some coal tars, that remain underground following gasification, are a potential source of localized ground-water contamination. However, the concentration of important contaminants, such as phenols, shows a significant decrease due to adsorption by the surrounding coal. Complementary laboratory measurements are providing detailed information concerning this adsorption process. We have also conducted laboratory and field measurements, in conjunction with modeling studies, to evaluate the effects of subsidence phenomena. Data from subsurface geotechnical instruments installed at the second gasification experiment, as well as measurements of ground-water levels, indicate that roof collapse connected the gasification cavity with overlying aquifers. The environmental implications of this interconnection aremore » being investigated. Our results suggest that hydrogeological site-selection criteria may be of considerable environmental importance in choosing locations for commercial-scale operations.« less

Catalyst-Feedstock-Engineering Interactions in Fluid Catalytic Cracking

Abstract: Fossil fuels, amassed over eons of geologic prehistory, are being irreversibly depleted about 106 times more rapidly than they were formed. With this sort of kinetics, there is little question that there exists, in the ultimate sense, an energy crisis [1–3]. That is, there will be fuel deficits for whatever time interval declining volumes of hydrocarbon reserves are not compensated for by increased supply from new energy sources such as nuclear, solar, and geothermal. In the interim period, the petroleum refiner is forced to utilize higher molecular weight, more hydrogen-deficient crudes, and crude fractions which have higher concentrations of impurities. Eventually, substantial quantities of “synthetic crudes” derived from coal, oil shale, tar sands, and bitumens may also become available.

High-Btu gas via in-situ coal gasification. [Review of Hoe Creek experiments]

Abstract: Underground coal gasification offers a relatively low cost, environmentally sound method to produce SNG from coal. The resource is huge and widely distributed. The results of recent underground coal gasification tests in the U.S. have been very encouraging. A brief review of the technology is given followed by a description of Lawrence Livermore Laboratory's recent underground coal gasification experiment, Hoe Creek No. 2, in which gas of 100 to 150 Btu/scf was produced using air injection, and 250 to 300 Btu/scf when injecting steam and oxygen. Plans for future experiments are also described.

Microbiological desulfurization of coal

Abstract: A method for reducing the sulfur content of coal wherein comminuted coal is contacted with an enrichment culture which contains acid tolerant Thiobacillus species in combination with acid tolerant hetrotrophic microorganisms in an amount effective to act in a symbotic or synergistic manner with the Thiobacillus species. The initial pH of the coal culture combination may be selected so as to enhance the development of a commercially practical rate of sulfur removal.

Vesicular-arbuscular mycorrhizas in plants colonizing black wastes from bituminous coal mining in the illawarra region of new south wales

Abstract: SUMMARY Three commercial coal tips in the Illawarra region of New South Wales were investigated for the incidence of VA mycorrhizas in plants growing on them. All the plants examined except species of Personia and Banksia (Proteaceae) were infected by VA mycorrhizal fungi. Infection level ranged from 0 to 88%. Three main types of fungal endophytes, namely Glomus macrocarpus var. macrocarpus, Glom us mosseae, and Sclerocystis rubiformis, were identified. The possible role of VA mycorrhizas in plant colonization of coal spoil areas is discussed. The method of colorimetric quantification of VA infection was found a useful alternative to the slow and tedious method of clearing and staining. But the pigment-extraction method is reliable only for measuring mycorrhizal infection in controlled short term experiments. This method, however, cannot be used to analyse infection in field-grown, long established roots.