Showing papers on "Coal published in 1975"

Stach's Textbook of coal petrology

Abstract: This book includes the origin of coal, its petrographic constitution, changes in the macerals during coalification, techniques of coal petrology and their application to problems of palaeobotany, geology, oil and gas prospecting, coal assessment, coal evaluation, and fuel technology. This is the Third Edition of this textbook. (DP)

Pathways of thirty-seven trace elements through coal-fired power plant

Abstract: Coal, fly ash, slag, and combustion gases from a large cyclone-fed power plant 870 MW(e) were analyzed for a suite of elements. Mass balance calculations show that the sampling and analyses were generally adequate to describe the flows of these elements through the plant. Most Hg, some Se, and probably most Cl and Br were discharged to the atmosphere as gases. As, Cd, Cu, Ga, Mo, Pb, Sb, Se, and Zn were quite concentrated in fly ash compared to the slag, and were more concentrated in the ash discharged through the stack than in that collected by the precipitator. Al, Ba, Ca, Ce, Co, Eu, Fe, Hf, K, La, Mg, Mn, Rb, Sc, Si, Sm, Sr, Ta, Th, and Ti show little preferential partitioning between the slag and the collected or discharged fly ash. Cr, Sc, Na, Ni, U, and V exhibit behavior intermediate between the latter two groups. (auth)

Method of pyrolysis of coal in situ

Abstract: A method of pyrolysis of coal in situ includes the steps of establishing a pair of passages between a sub-surface coal formation and the surface with the coal passages being adapted to separately remove liquids and gases from the coal formation, establishing a sump at the bottom of the passages which extends at least partially below the coal formation to receive liquid volatile material released from the formation, and heating the coal formation so that initially tars in the formation will migrate radially until they go beyond the heated area whereupon they will solidify and form a hermetic barrier around the zone to be pyrolyzed to confine gaseous liquid volatile materials released from the coal as a result of the pyrolysis. The released gaseous materials can then flow to the surface through one of the passages and the liquid volatile material can flow into the sump and be pumped to the surface through the other passage.

In situ solution mining of coal

Abstract: Underground strata surrounding a coal seam are prestressed by repeated fracturing with a settable material to strengthen and seal the strata to contain a hydrostatic pressure in the coal seam of about 100 to about 500 atmospheres, thereby providing a gas and liquid-tight seal surrounding and within the coal seam. After the strata surrounding the coal seam and the coal seam itself are sealed, an hydrogenating agent is supplied to the coal seam and is maintained at a temperature of approximately 300 to 500 degrees centigrade and a pressure of from about 100 to about 500 atmospheres to liquefy and hydrogenate the coal in situ. When a region of coal is liquefied out to the boundary of the prestressing, the liquefied coal is pumped out for use.

Elemental concentrations in the National Bureau of Standards' environmental coal and fly ash Standard Reference Materials

Abstract: The four participating laboratories measured the concentrations of 37 elements in NBS standard coal (SRM 1632) and 41 in fly ash (SRM 1633). Most of the measurements were done by instrumental neutron activation analysis, which was done by each of the laboratories. In addition, one laboratory used instrumental photon activation analysis and another counted the natural radioactivity to determine concentrations of K, Th, and U. The results obtained are in good agreement with the values given by NBS for the twelve elements in each material for which both they and we have values. For most elements for which comparisons can be made, the interlaboratory dispersion of results obtained in this work is much less than was obtained in a recent roundrobin analysis of these materials by many laboratories using a variety of techniques. Average concentrations for the 37 elements in the coal standard and 41 elements in the fly ash standard are presented for comparison with results that may be obtained by other laboratories.

Acid-base structure of coal-derived asphaltenes.

Abstract: Asphaltenes, the key intermediates in the liquefaction of bituminous coals, consist of hydrogen bonded complexes which can be separated into their acidic and basic components. The acidic components contain all, while the basic components contain none, of the exchangeable protons present. The significance of these findings with respect to coal structure and coal solubilization is discussed.

In situ coal combustion heat recovery method

Abstract: A method for recovery of heat generated by the combustion of coal in situ within coal seams in the earth. Three embodiments are described: one, in which the coal seam crops out and into which can be drilled and inserted a pipe, through the coal seam, to a central point, where it is joined with a vertical pipe drilled from the surface. Water is supplied to the pipe at the point of outcrop. Fires are started within the coal seam and supplied with air from the surface by means of drilled boreholes. The heat of combustion converts the water in the pipe to steam which travels up the vertical pipe and is used to drive a turbine generator system. A second embodiment is used where there is an overlying aquafer above the coal seam. Fires are started by means of air supplied through boreholes leading from the surface into the coal seam. The heat of combustion converts the water in the aquafer to steam, which then is circulated out of the aquafer and up to the surface where it drives a turbine generator system. A third embodiment uses the hot combustion gases to heat water to steam in pipes in a vertical borehole.

Aromatic units in coal

Abstract: THE organic matter in coal consists largely of a macromolecular material of complex and variable composition. When coal is pyrolysed, a large fraction is converted to char, and a number of complex aromatic compounds are formed. Because of the extensive chemical change which takes place during this process, however, it is not clear what relationship the products have to the original structure of coal. Many workers have used oxidation procedures to degrade coal to simpler species which are more readily interpreted in terms of coal structure. Oxidation products, however, were in general studied by limited classical organic chemistry methods for separation and identification of products1,2. To date the only aromatic acids definitely identified have been the carboxylic acids of benzene3,4. Commonly used oxidants have been HNO3, HNO3–K2Cr2O7, KMnO4, O2 and H2O2–O3 in conditions for drastic degradation of aromatic rings. On the basis of results of oxidation of coal with a selective oxidant, NaOCl, Chakrabartty and Berkowitz have suggested5 that coal has a largely non-aromatic “tricycloalkane or polyamantane” structure. They pointed out that no evidence for aromatic compounds other than benzene derivatives was found in their oxidation product. Our experimental data do not support this view but rather the generally accepted idea that coal is predominantly an aromatic material.

An Empirical Study of the Relation of Chemical Properties to Ash Fusion Temperatures

Abstract: Regression analysis is used to develop equations for calculating fusion temperatures of coal ash from chemical composition, based on 1250 analyses of ash from both eastern and western US coal. Standard errors for the equations are generally less than 27/sup 0/C, which is the analytical tolerance of the ash fusion temperature measurements. Equations are given for eastern, western and combined eastern and western coals. These equations: (1) provide a technique for calculating ash fusion temperatures from the chemical composition of the ash; (2) provide a method for calculating the ash fusion properties of coal blends; and (3) provide an improved understanding of the effect, significance and interactions of ash elements with respect to the thermal properties of coal ash.

Hydrogen production by catalytic coal gasification

Abstract: Coal is catalytically reacted with steam to produce hydrogen. Various Group I metal salts such as K 2 CO 3 , Na 2 CO 3 and borax are used as catalysts. These catalysts are stabilized with fluoride containing salts such as CaF 2 to thereby extend their life. Alternatively, NaF was found to be a thermally stable catalyst for the reaction.

Conversion of coal to high octane gasoline

Abstract: An integrated process for converting coal to high octane gasoline by gasifying the coal in such manner as to form a gas comprising carbon oxides, hydrogen and methane; contacting this gas in one or a series of steps with one or a series of catalysts, respectively comprising a special high silica to alumina ratio zeolite; converting the carbon oxides and hydrogen by such contact to a product comprising water, high octane aromatic gasoline and light hydrocarbon gases; alkylating the C3 and C4 olefins with the isobutane in the light gases to produce alkylate gasoline; admixing the aromatic and alkylate gasoline; and subjecting the C2 - portion of the product to steam reforming whereby additional synthesis gas to be admixed with the gas produced by coal gasification is formed.

In situ complete stress-strain characteristics of large coal specimens

Abstract: The significance of in situ tests on large coal specimens is briefly reviewed. Tests aimed at obtaining complet~ stress-strain characteristics of large coal specimens with high width-to-height ratios are descriptionbed. A formula for the relationship between strength and width-to-height ratios of coal pillars is proposed, and the influence of widthto- height ratios on the deformation characteristics of pillars is discussed.

Trace element discharges from coal combustion for power production

Abstract: Partition factors have been calculated to describe the distribution of 38 elements between slag, total fly ash, atmospherically emitted fly ash, and vapors for a coal fired steamplant. These factors have been generalized to other types of boilers, to calculate the annual U.S. discharge of trace elements due to coal combustion for power production. The magnitude of trace element mobilization by coal combustion is compared with industrial consumption of trace elements, and with estimates of their natural mobilization by weathering. Elemental flows due to coal consumption are never less than 1.5% of their weathering mobilization, and coal combustion introduces As, Co, Cu, Fe, Hg, Mo, Ni, Pb, Sc, Se, U, V, and Zn into the environment at rates comparable to their rates of introduction by weathering.

Process for gasifying carbonaceous solids and removing toxic constituents from aqueous effluents

Abstract: Toxic trace element pollutants present in the raw product gas and raw flue gas streams produced during the gasification of coal or similar carbonaceous solids containing sulfur and such trace elements are recovered by separately scrubbing the product gas and flue gas with water, combining the resulting aqueous effluents, and removing the pollutants from the combined aqueous stream as insoluble metal sulfides.

Coal passivation process

Abstract: Low rank coals such as subbituminous or lignites containing more than about 10 weight percent moisture are dried and passivated against reabsorption of moisture in a fluidized bed by heating the particulate coal with a warm inert gas passing upwardly through the bed and simultaneously coating the warm particulate coal with a heavy liquid hydrocarbon material. Such coating aids in the removal of the moisture and prevents the reabsorption of moisture by the coal and thereby prevents consequential heating and possibly spontaneous ignition of the coal during its subsequent transportation or storage.

Coal petrology and the formation of coal seams in some Australian sedimentary basins

Abstract: Petrographic composition of coal seams is discussed in connection with the rate of subsidence in some Australian sedimentary basins. Cyclic variation of floor/dirt band --> vitrinite-rich coal --> vitrinite-poor coal --> dirt band/roof can be seen within a seam. Coal seams deposited under unstable conditions are composed of incomplete cycles which lack vitrinite-poor coal, and so are rich in vitrinite, while coal seams deposited under stable conditions are composed of a few complete cycles, and are relatively poor in vitrinite. Such a contrast between coal seams can be seen within a sedimentary basin such as the Sydney Basin in Australia. Coal seams in "shelf sediments" on the stable basement rocks are, for the same reason, much poorer in vitrinite than those deposited under more variable conditions.

Method and apparatus for removing volatile fluids

Abstract: A method and apparatus for the removal and recovery of volatile or evaporable substances from materials containing them. In other embodiments, the invention is readily applicable for the simultaneous incineration and concentration of such materials, particularly spent water-diluted effluents from industries and municipalities as well as for the generation of electric power from various thermal fuels, particularly power gas produced from coal or oil. In further embodiments, the reclamation of oil, from oil sands and shales, is effected as well as the cyclic pulping of cellulosic materials with cyclic recovery of heat and chemicals.

Gasification of carbonaceous solids

Abstract: A process and apparatus for converting coal and other carbonaceous solids to an intermediate heating value fuel gas or to a synthesis gas. A stream of entrained pulverized coal is fed into the combustion stage of a three-stage gasifier along with a mixture of oxygen and steam at selected pressure and temperature. The products of the combustion stage pass into the second or quench stage where they are partially cooled and further reacted with water and/or steam. Ash is solidified into small particles and the formation of soot is suppressed by water/steam injections in the quench stage. The design of the quench stage prevents slag from solidifying on the walls. The products from the quench stage pass directly into a heat recovery stage where the products pass through the tube, or tubes, of a single-pass, shell and tube heat exchanger and steam is generated on the shell side and utilized for steam feed requirements of the process.