Showing papers on "Methane published in 1980"

In situ combustion process for the recovery of liquid carbonaceous fuels from subterranean formations

Abstract: An integrated in situ combustion process for producing subterranean carbonaceous deposits in which the resulting flue gas of low heating value is combusted over an oxidation catalyst at substoichiometric conditions and is expanded in a gas turbine which drives the air compressor for injecting the combustion air into the underground carbonaceous deposit. An oxidation catalyst is provided for reducing carbon monoxide in the combusted flue gas comprising platinum and palladium.

Methane-steam reforming

Abstract: For more than 40 years the catalyzed hydroearbon-steam reforming reaction has been of commercial value. The first units commissioned in the 1930s were run on light hydrocarbon feedstock at atmospheric pressure [l], It took until 1962 for a 15-atm steam reformer to come on-stream in the United Kingdom using liquid hydrocarbon feedstock [2–4].

Anaerobic methane oxidation: occurrence and ecology.

Abstract: Anoxic sediments and digested sewage sludge anaerobically oxidized methane to carbon dioxide while producing methane. This strictly anaerobic process showed a temperature optimum between 25 and 37°C, indicating an active microbial participation in this reaction. Methane oxidation in these anaerobic habitats was inhibited by oxygen. The rate of the oxidation followed the rate of methane production. The observed anoxic methane oxidation in Lake Mendota and digested sewage sludge was more sensitive to 2-bromoethanesulfonic acid than the simultaneous methane formation. Sulfate diminished methane formation as well as methane oxidation. However, in the presence of iron and sulfate the ratio of methane oxidized to methane formed increased markedly. Manganese dioxide and higher partial pressures of methane also stimulated the oxidation. The rate of methane oxidation in untreated samples was approximately 2% of the CH4 production rate in Lake Mendota sediments and 8% of that in digested sludge. This percentage could be increased up to 90% in sludge in the presence of 10 mM ferrous sulfate and at a partial pressure of methane of 20 atm (2,027 kPa).

The deep earth gas hypothesis

Abstract: Earthquakes, volcanic eruptions, and outgassing phenomena all point to a release of gases generated from primordial hydrocarbons at deep levels in the earth. Buried under conditions of high pressure and temperature, these original, nonbiological hydrocarbons liberate methane as the principal mobile component. The methane migrates up toward the earth's surface where it is (1) liberated through faults, (2) oxidized to CO/sub 2/ in hot volcanic lava, (3) trapped below impermeable strata, or (4) dissolved in hydrocarbon deposits of biological origin. If this theory is correct, large quantities of gas exist in deep, but still accessible, regions 15,000-30,000 ft below the earth's surface.

Fossil charcoal as evidence of past atmospheric composition

Abstract: The presence of charcoal in the geological record offers a new approach to assessing oxygen levels in palaeoatmospheres. Charcoal is formed by the incomplete combustion of woody tissues. The combustion of wood is supported by the generation of the combustible gases carbon monoxide and methane during the pyrolysis process. As the combustion ranges of these gases are restricted with decreasing oxygen availability to a level below which no combustion will occur, the production of charcoal and its appearance in the geological column constitute a record of changing oxygen availability through time. We show here that the occurrence of charcoal in rocks from the Lower Carboniferous onwards suggests that atmospheric oxygen never fell below 0.3 of present atmospheric level (PAL) during this time. Detrital charcoal formed by forest fire must have contributed an appreciable fraction to inert carbonaceous matter in sediments (kerogen) during post-Devonian time.

The evolution of atmospheric ozone

Abstract: A one-dimensional coupled chemistry and flow model of the earth's atmosphere is used to study the relationship between ozone content and oxygen level. The effects of the biogenic trace gases methane and nitrous oxide are considered, as well as the production of odd nitrogen in lightning discharges. The ozone column depth is found to increase monotonically with increasing oxygen content, in contrast with previous predictions that the column depth should peak at ∼10−1 PAL (present atmospheric level) of O2. The critical O2 level at which an effective ultraviolet shield is produced is in the neighborhood of 10−1 PAL. Implications of this result for the emergence of terrestrial land life are considered.

Cryogenic distillative separation of acid gases from methane

Abstract: Method of eliminating solids formation in a cryogenic distillative separation of acid gases from methane. This method comprises adding a solids-preventing agent to the solids potential zone of the distillation column. Typical solids-preventing agents are one or more C2-C5 alkanes, or other nonpolar liquids which are miscible with methane at the column conditions. The elimination of solids formation permits a more complete separation to be achieved.

Experimental evidence against an appreciable isotopic fractionation of methane during migration

Abstract: Previously there has been much confusion regarding the magnitude and direction of the isotopic fractionation resulting from the migration of methane. Experimental results plus a mathematical simulation indicate that migration fractionation will nearly always be negligible for both the carbon and hydrogen of methane. By far the most likely cause of migration fractionation of methane is the difference in water solubility of 12CH4 and 13CH4. In most cases this fractionation will not exceed a negligible 1-permil depletion of 13C in the methane of a commercial accumulation.

Stratification of aerobic methane‐oxidizing organisms in Lake Mendota, Madison, Wisconsin1

Abstract: The microflora responsible for methane oxidation are stratified in a narrow band in the thermocline of Lake Mendota where dissolved oxygen is low during summer. Oxygen sensitivity of growth of these organisms or of methane oxidation cannot account for their absence from the epilimnion because oxygen does not inhibit either process under in situ conditions at concentrations exceeding those measured in natural samples. The dissolved inorganic nitrogen content of samples where methane oxidation rates were highest was >l mgeliter-’ in summer 1977. We could not obtain evidence of in situ nitrogen fixation although enrichment cultures grew on nitrogen-free media and fixed 15N2. Nitrite was present at the position in the water column of maximum methane oxidation; this suggests that methanotrophic bacteria co-oxidized ammonia. The distribution of methanotrophs in the lake indicated that their position in the water column at each time of year was determined by the concentration profiles of oxygen and methane. Methane oxidation in summer depletes the methane in the epilimnion and the absence of oxygen in the hypolimnion precludes growth of the organisms there. At other times of year the rates of oxidation of methane seem to be determined by the concentration of methane in the water. The rate of oxidation of methane by a sample was increased by additional methane when the in situ concentration was <5 PM.

Anaerobic metabolism of particulate organic matter in the sediments of a hypereutrophic lake

Abstract: SUMMARY. The anaerobic decomposition of particulate organic matter (POM) was examined in the anoxic pelagic sediments of hypereutrophic Wintergreen Lake. Degradation of sedimented POM occurred rapidly as shown by increased production and release of ammonia, hydrogen sulphide, volatile fatty acids and methane from the sediments 2–3 weeks after large inputs of organic matter. Maximum concentrations of most metabolites were found at the sediment-water interface, indicating that the initial anaerobic degradation of freshly deposited POM occurred at this site. The absence of the inorganic electron acceptors, nitrate and sulphate, suggested that fermentation and methanogenesis were the major anaerobic processes involved in the dissimilation of organic matter in these sediments during stratified periods. The amount of carbon input converted to methane in the sediments was determined from May to early November 1976 and 1977. Carbon output as methane was measured by quantifying methane lost from the sediments by ebullition and by estimating soluble methane lost to the water column by diffusion. Total methane release during summer stratification accounted for 34% of the particulate organic carbon input to the sediments in 1976 and 44% in 1977. Methane release was directly related to the rate of sedimentation of POM. However, methane production was temporarily inhibited following high rates of sedimentation in 1976, suggesting that the rate of organic loading may be an important factor controlling anaerobic decomposition in these sediments.

Origin of hydrogen in methane produced by Methanobacterium thermoautotrophicum.

Abstract: The production of deuterated methane by Methanobacterium thermoautotrophicum in H2O-D2O mixtures was examined by high-resolution mass spectrometry. The hydrogen in the methane arose solely from water and not from hydrogen gas. Hydrogen gas served only as an electron source in methanogenesis. A whole-cell product isotope discrimination of 1.5 favoring hydrogen over deuterium was observed in methane production in 81 atom% deuterated water. The distribution of deuterated methane species is described by a simple model of the overall reaction.

Gas production by accelerated in situ bioleaching of landfills

Abstract: A process for improved gas production and accelerated stabilization of landfills by accelerated in situ bioleaching of organic wastes by acid forming bacteria in substantially sealed landfills, passing the leachate of hydrolysis and liquefaction products of microbial action of the microorganisms with the organic material to an acid phase digester to regenerate the activated culture of acid forming microorganisms for recirculation to the landfill, passing the supernatant from the acid phase digester to a methane phase digester operated under conditions to produce methane rich gas. The supernatant from the methane phase digester containing nutrients for the acid forming microorganisms and added sewage sludge or other desired nutrient materials are circulated through the landfill. Low Btu gas is withdrawn from the acid phase digester while high Btu gas is withdrawn from the methane phase digester and may be upgraded for use as SNG. The process of this invention is applicable to small as well as large organic waste landfills, provides simultaneous disposal of municipal solid waste and sewage sludge or other aqueous organic waste in a landfill which may be stabilized much more quickly than an uncontrolled landfill as presently utilized.

Carbon dioxide and methane fluxes from the ombrotrophic parts of a subarctic mire

Abstract: A field study is presented of carbon dioxide and methane fluxes to the atmosphere in relation to temperature and moisture for the ombrotrophic parts of the subarctic mire at Stordalen (Swedish IBP Tundra Biome study site). Measurements were made on six occasions over a season of 145 days, and a regression model explaining 69% of variation was obtained for carbon dioxide versus temperature and moisture. Using a mean moisture value for the season and temperature as a driving force in the regression model, a flux of 33.1 g C m"2 yr-1 was calculated. This value included respiration by mosses in darkness, roots, soil fauna and microorganisms, which were estimated to account for 20, 10, 3 and 67% respectively. The temperature response showed the usual pattern: QlQ-values were found to increase with decreasing temperature. The Q10-values also increased with moisture content in the peat. The methane flux was found not to be correlated with temperature, but moisture could explain 30% of the variation. However, a methane flux of 0.6 g C m~2 yr-1 was estimated, which is 1.8% of the total carbon flux.

Methane Generation and Petroleum Migration

Abstract: The outstanding contribution of methane generation to petroleum migration is as a major source of internal energy to move fluids within the petroleum source system. In the early stages of sediment consolidation, methane generation is largely the result of bacterial action, and most of the gas produced escapes readily along with large volumes of compaction water, either to the surface or to associated reservoirs. However, with increasing depth of burial, bacterial activity diminishes and is overlapped and replaced by thermochemical activity which increases in vigor with depth because of increasing temperature, and becomes responsible for generation of both gas and oil. If the volume of methane generated exceeds the capacity of interstitial water to take it into solution, free gas bubbles develop in the pore spaces and an internal fluid pressure begins to build up within the already dense, relatively impermeable sediment, in addition to the external pressure due to overburden. At the same time, a further inhibiting effect on fluid escape is caused by the presence now of two phases--liquid and gaseous--in the sediment which may effectively impede intergranular flow (Jamin effect). Eventually something will have to "give." As pressures rise to equal or exceed the weight of rock overburden, microfractures will begin to develop in the rock, allowing relief of pressure and permitting fluids to migrate to reservoir strata. The movement of hydrocarbons may be in part as a water solution and even as a continuous oil phase, but an important part may be as a solution of higher hydrocarbons in methane gas. Methane generation also may (under certain circumstances) play an inhibitive role in petroleum migration through the formation of impermeable methane-hydrate barriers and through development of impermeable, overpressured shale zones and diapirs. Illustrations of shale diapir and mud volcano activity are given to demonstrate the magnitude of the power that may be built up by methane generation.

The genesis of the methane in Lake Kivu (Central Africa)

Abstract: Large amounts of methane and carbon dioxide, among other gases, are dissolved in the deep water of Lake Kivu. There is no dispute about the primarily magmatic origin of the carbon dioxide, but models of the genesis of the methane have been contradictory up to now. They have been based on too few and partly too inaccurate data.

The Laminar Burning Velocity of Isooctane, N-Heptane, Methanol, Methane, and Propane at Elevated Temperature and Pressures in the Presence of a Diluent

Abstract: An electrically driven toy in which a transmission mechanism is disengaged through a manually operated change-over means from the driving power source when the energization of the power source is interrupted.