Showing papers on "Coal published in 1994"

Thermogenic and Secondary Biogenic Gases, San Juan Basin, Colorado and New Mexico--Implications for Coalbed Gas Producibility

Abstract: The San Juan basin is the most prolific coalbed gas basin in the world with 1992 production exceeding 440 Gcf (FOOTNOTE *) (124 billion m3), resources of approximately 50 Tcf (14 trillion m3), and proved reserves of over 6 Tcf (170 billion m3) Coalbed gas wells with the highest production (initial potential greater than 10 Mcf/day or 028 million m3/day) occur in the overpressured, north-central part of the basin Hydrologic analysis indicates that overpressure in the Fruitland Formation is artesian in origin and represents repressuring that developed during the middle Pliocene Highly permeable, laterally continuous coal beds override abandoned shoreline Pictured Cliffs sandstones and extend to the elevated recharge area in he northern basin to form a dynamic, regionally interconnected aquifer system Coal rank and basin hydrodynamics control the composition of Fruitland coalbed gases, which varies significantly across the basin Chemically dry gases in the north-central part of the basin coincide with meteoric recharge and regional overpressure The consistency of methane ^dgr13C values across the basin, the presence of isotopically heavy carbon dioxide in coalbed gases and bicarbonate in formation waters, and biodegraded n-alkane distributions of some coal extracts indicate that coalbed gases in the north-central basin are a mixture of thermogenic (25-50%), secondary biogenic (15-30%), and migrated thermogenic (12-60%) gases Migrated, conventionally and hydrodynamically trapped gases, in-situ generated secondary biogenic gases, and solution gases result in gas content that plot on or above the coal sorption isotherm Bacteria transported basinward in groundwater flowing from the elevated northern basin margins metabolized wet gas components, n-alkanes, and organic compounds in the coal and generated secondary biogenic methane and carbon dioxide subsequent to coalification, uplift, erosion, and cooling These gases may be limited to basin margins, where shallow depths and structural deformation result in higher permeability, or may extend more than 35 mi (56 km) basinward from the recharge zone The presence of appreciable secondary biogenic gas indicates an active dynamic flow system with overall permeability sufficient for high productivity Basin hydrogeology, reservoir heterogeneity, location of permeability barriers (no-flow boundaries), and the timing of biogenic gas generation and trap devel pment are critical for exploration and development of unconventional gas resources in organic-rich rocks

Reliability and reproducibility of leaching procedures to estimate the modes of occurrence of trace elements in coal

Abstract: The 1990 amendments to the Clean Air Act have renewed interest in chemical forms or modes of occurrence of trace elements for potentially toxic trace elements in coal. Selective solvent leaching has been useful in estimating these modes of occurrence. This technique is much faster than previous attempts to determine the modes of occurrence of trace elements in coal, such as scanning electron microscopy, analysis of density separates of coal and low-temperature ash. However, relatively little has been published about the reproducibility and reliability of the solvent leaching procedure. For this paper, three previously analyzed coal samples were leached individually and (or) sequentially using procedures described previously. The concentrations of 45 elements were determined by analyzing the leachate by inductively coupled argon plasma-atomic emission spectroscopy (ICAP-AES) and (or) the residue by instrumental neutron activation analysis (INAA).

Process of development of coal seams and complex of equipment for its implementation

Abstract: FIELD: mining industry. SUBSTANCE: development of coal seams is conducted in columns or stopes by burning and gasification of coal in seam. Products of gasification after proper cleaning and preparation by electrochemical method are transformed into electric power with the aid of battery of fuel cells. Product of oxidation of hydrogen - one of basic components of fuel mixture (products of coal gasification), namely water is transformed in recovery boiler into water steam thanks to after-burning of residues of fuel used in battery of fuel cells which is fed together with inert carbon dioxide produced by oxidation of carbon oxide of fuel mixture into zone of burning of coal in seam and hydrogen and carbon oxide regenerated in it are supplied again into battery of fuel cells. EFFECT: improved efficiency of gasification of coal. 6 cl, 2 dwg

The Structure and Reaction Processes of Coal

Abstract: Introduction. Selection of a Suite of Commonly Used Research Coals. Geochemistry and Macromolecular Structure of Coal. Coal Structural Characterization by Advanced Techniques. Devolaltilization Rate Processes and Products. Char Oxidation, Conversion, and Reaction Rate Processes. Index.

Arsenic mobilization and bioavailability in soils.

Abstract: The paper identifies the natural and anthropogenic sources of arsenic in the environment. Anthropogenic sources include mining and smelting activities, pesticide use, coal, coal combustion by products and sewage sludge. It goes on to discuss arsenic concentrations in natural soils, speciation of arsenic in the soil environment, and arsenic in pyritic mine spoils and inland acid sulfate soils, arsenic concentrations in arsenic-contaminated soils, and arsenic in coal and coal combustion residues applied to land. Further sections cover arsenic in sediments, groundwater contamination with arsenic, and arsenic in higher plants. 178 refs., 3 figs., 3 tabs.

Coalbed Methane: Principles and Practice

Abstract: Methane stored in coalbeds has emerged as an energy source that offers a viable, cleaner-burning and abundant alternative to fossil fuels. The recovery of coalbed methane requires a combination of oilfield and coalmining as well as new processes. This reference work discusses the principles of methane storage in coal and the practices of producing the methane economically on a commerical scale, and provides an overall analysis of the coalbed methane process. It also documents the formation, structure and properties of coal from the standpoint of importance to methane production and details the oilfield engineering operations as modified for the production of methane from coal.

Use of nitrogen from an air separation unit as gas turbine air compressor feed refrigerant to improve power output

Abstract: The present invention is an improvement to a process for the production of work to generate electricity or to drive a mechanical device using a gas turbine. In the process, feed air stream is compressed and combusted with a fuel gas to produce a combustion product. This combustion product is expanded in a gas turbine expander, thereby producing a hot exhaust gas and work. This produced work is used to generate electricity or to drive a mechanical device. The improvement to the process, which increases the work produced by the gas turbine expander, is characterized by cooling nitrogen product, produced by a cryogenic air separation unit to a subambient temperature and combining this subambient cooled, nitrogen product with the feed air stream prior to compression. The improvement of the present invention is particularly suited to the process, wherein at least a portion of the oxygen product produced by the cryogenic air separation unit is reacted with a carbonaceous feedstock in a gasification unit to produce the fuel gas, which is rich in carbon monoxide and hydrogen. The carbonaceous feedstock reacted in the gasifier unit can be coal, petroleum coke, tar sands bitumen, tar sand emulsion, municipal wastes, petroleum residua, waste oil or mixtures thereof.

The oil-generating potential of plants from coal and coal-bearing strata through time: a review with new evidence from Carboniferous plants

Abstract: Abstract A combination of microscopy and chemistry is used to characterize high molecular weight components of plant material which contributed to Carboniferous coals and coal-bearing strata. Material was selected from coals, paper coals, coal balls, oil-shales and shales and included cuticles from stems and leaves, periderm from stems and rooting systems, spore walls, algal cell walls and ‘resin’ rodlets. Chemical analyses were undertaken using Curie-point pyrolysis-gas chromatography (-mass spectrometry) (Py-GC-(MS)) and 13C solid state Nuclear Magnetic Resonance (NMR). Light microscopy and scanning electron microscopy were used to ensure a detailed understanding of the plant material which was analysed chemically. This study has emphasized those plants, plant tissues and organs which are known to have been dominant or major contributors to Carboniferous coals and coal-bearing sequences: arborescent lycophyte periderm (Diaphorodendron stems and Stigmaria rhizomorphs); pteridosperm cuticles (medullosan (e.g. Alethopteris) and Karinopteris), lycophyte stem cuticle (Eskdalia) and arborescent lycophyte spores (megaspores and microspores). Several algal cell walls (Tetraedron, Tasmanites and Gloeocapsomorpha) and the ‘resin’ rodlets derived from medullosan pteridosperm petioles have also been analysed. Results show that all of these elements (except resins) contain (or are dominated by) highly resistant, highly aliphatic macromolecules which have the potential to yield, upon catagenesis, n-alkanes which are found in crude oils. Resins potentially contribute cyclic hydrocarbons to crude oils. Combining all this evidence it is concluded that Carboniferous coals are oil prone and that explanations for the absence of oil-pools derived from such coals must be sought in geological or exploration factors and not in the nature of the coals themselves. A review of coal-forming floras through time, and of suggested terrestrially sourced oils and their parent coals, leads us to conclude that high molecular weight components of higher plant materials have potentially made a major contribution to oils sourced from coals and coal-bearing strata over a long period of geological time (Devonian onwards). Cell walls of freshwater algae have made a comparable contribution since the Ordovician. The oil-generating potential of each coal or organic-rich sediment will depend upon a combination of depositional environment and the floristic and chemical composition of the source vegetation and its component plants and plant parts.

Coliquefaction of waste plastics with coal

Abstract: Polyethylene (PE), poly(ethylene terephthalate) (PET), polypropylene (PPE), and actual plastic wastes from such items as milk jugs, soft drink bottles, plastic wraps, plastic flatware, etc., have been successfully converted to oil in direct liquefaction experiments with coal. Comparative experiments were performed with and without the presence of coal under typical direct liquefaction conditions (420-450°C, 60 min reaction time, 800 psig of H 2 cold). Two types of catalysts were used: highly dispersed iron-based catalysts, and an HZSM-5 zeolite catalyst. Using PE, PPE, PET, and a mixed waste plastic with the zeolite catalyst, oil yields of 80-98% and total conversions of 90-100% were obtained at liquefaction temperatures of 420-430°C

Coal Mine Roof Rating (CMRR): A practical rock mass classification for coal mines. Information circular/1994

Abstract: The Coal Mine Roof Rating (CMRR) was developed by the U.S. Bureau of Mines as an engineering tool to quantify descriptive geologic information for use in coal mine design and roof support selection. The CMRR system combines the results of many years of geologic ground control research with worldwide experience with rock mass classification systems. Like other classification systems, the CMRR begins with the premise that the structural competence of mine roof rock is determined primarily by the discontinuities that weaken the rock fabric. The CMRR makes four unique contributions: (1) it is specifically designed for bedded coal measure rocks, (2) it concentrates on the bolted interval and its ability to form a stable mine structure, (3) it is applicable to all U.S. coal seams, and (4) it provides a methodology for data collection. Using only simple field tests and observations, the CMRR can be calculated from roof falls, overcasts, and highwall exposures.

Geological and hydrological controls on the producibility of coalbed methane

Abstract: Geological and hydrological comparison of two United States coalbed methane basins, the prolific San Juan Basin and the marginally producing Sand Wash Basin, indicates that coal distribution and rank, gas content, permeability, ground-water flow, and depositional and structural setting are critical controls on coalbed methane producibility. A complex interplay, and moreover, a synergy amongst these controls determines high productivity. This paper proposes a basin-scale explanation for the prolific and marginal production in the two basins and that can be applied to evaluation of coalbed methane potential in coal basins worldwide. High productivity is governed by (1) thick, laterally continuous coals of high thermal maturity, (2) basinward flow of ground water through coals of high rank and gas content orthogonally toward no-flow boundaries (regional hingelines, fault systems, facies changes, and/or discharge areas), and (3) conventional trapping along those boundaries to provide additional gas beyond that sorbed on the coal surface.

An Environmental History of Britain Since the Industrial Revolution

Abstract: Part 1 Pollution and amenity: the age of smoke and smells - measurement of pollution, the domestic fire, industrial smoke, acid dust and smells, remedies for atmospheric pollution from smoke abatement to global warming - deadly fog, the smokeless zone, the Clean Air Act, competition for coal, invisible pollutants, global warming, new sources of energy, effects of air pollution on health water resources under strain - the water polluters, remedies for water pollution, state of the rivers, treatment of sewage, the last 60 years land loss and reclamation - costal erosion, land reclamation, erosion inland, forestry, loss of agricultural land to other uses towards a green and pleasant land - a feeling for the past conservation of buildings and monuments, access to the countryside, noise pollution. Part 2 The prodigal economy - and its reform?: energy - coal reserves, substitutes for coal, energy prices, economy in the winning and use of coal, the demand for energy metals and minerals - reserves of metal ores in Britain, substitution, metal prices any old iron? - recyling, manufacture of shoddy, waste heat recovery, glass and metals, hazardous waste, high-tech scrap collection, scrap and total supply of metals by-products - by-products of coal, the alkali manufacture, soap-making, fertilisers, building materials, the decline of by-products? Conclusion - the quality of goods, economies of time and labour, economic growth and exhaustible resources.

Impact of coal pyrolysis on combustion

Abstract: The pyrolysis process has impacts throughout coal combustion. The roles of pyrolysis in various aspectsof the coal combustion process are described, including the devolatilization yield, nitrogen release, softening and swelling, soot formation, and char reactivity. These processes can be understood and quantitatively predicted using recently developed network pyrolysis models that describe the transformation of the coal's chemical structure. The models are described and examples of their predictive ability for important coal combustion phenomena are presented.

Paleoenvironmental and environmental implications of the boron content of coals

Abstract: The objective is to determine the concentration of boron in Australian and Canadian coals in order to assess the variation of boron in coal with respect to rank, age, geological setting, and the degree of paleosalinity in the coal forming environment. The boron content in coal seams is sensitive to the environment of deposition and to the degree of marine influence during the early stages of coalification. The variation of boron in heat affected coal seams indicates that the behaviour of boron during the natural heating and burning of coal depends on the temperature of the system and the nature of the process. The dispersion of boron after combustion and the environmental effects of boron are considered. 222 refs., 61 figs., 23 tabs.