Showing papers on "Natural gas published in 1990"

A comparison of the contribution of various gases to the greenhouse effect

Abstract: The current concern about an anthropogenic impact on global climate has made it of interest to compare the potential effect of various human activities. A case in point is the comparison between the emission of greenhouse gases from the use of natural gas and that from other fossil fuels. This comparison requires an evaluation of the effect of methane emissions relative to that of carbon dioxide emissions. A rough analysis based on the use of currently accepted values shows that natural gas is preferable to other fossil fuels in consideration of the greenhouse effect as long as its leakage can be limited to 3 to 6 percent.

Correlation of reservoired gases using the carbon isotopic compositions of wet gas components

Abstract: The carbon isotopic compositions of the wet gas components, particularly propane, isobutane, and normal butane, have been found to be particularly valuable for correlating one reservoired gas with another. The usefulness of these components for correlation results from their carbon isotopic compositions reflecting both the nature of their source and their maturity. This source control is strongest for gases derived from the more highly structured types of kerogen (i.e., woody-coaly; type III), although the wet gas components' carbon isotopic compositions of most gases are at least partly controlled by their source for levels of maturity below the point at which thermal destruction of the wet components occurs. As a result, the wet gas components are found to provide more ositive correlations than is methane alone. Three exploration examples illustrate the use of the carbon isotopic compositions of the wet gas components for correlation: the Leduc reef trend of Alberta, Canada; the Sleipner area in the North Sea; and the Lena field, offshore Louisiana, United States. The three examples also illustrate the need to integrate geochemical interpretations with regional geology to obtain a good understanding of the hydrocarbon source.

Adaptive Simulation of Gas Turbine Performance

Abstract: Greater use is being made of dynamic simulation of energy systems as a design tool for selecting control strategies and establishing operating procedures. This paper discusses the dynamic modeling of a gas-fired combined-cycle power plant with a gas turbine, a steam turbine, and an alternator-all rotating on a common shaft. A waste-heat boiler produces steam at two pressures using heat from the gas turbine flus gas. The transient behavior of the system predicted by the model for various upset situations appears physically reasonable and satisfactory for the operating constraints

Power generation from lng

Abstract: LNG (9) is pumped to high pressure (13) vaporized (19), further heated (21) and then expanded to create rotary power (29) that is used to generate electrical power (31). A reservoir of carbon dioxide at about its triple point (41) is created in an insulated vessel to store energy in the form of refrigeration recovered from the evaporated LNG. During peak electrical power periods, liquid carbon dioxide is withdrawn therefrom, pumped to a high pressure (45), vaporized (47, 75) further heated (55), and expanded to create rotary power (57) which generates additional electrical power (59). The exhaust from a fuel-fired combustion turbine (61), connected to an electrical power generator (63), heats the high pressure carbon dioxide vapor. The discharge stream from the CO2 expander is cooled (53) and at least partially returned to the vessel (41) where vapor condenses by melting stored solid carbon dioxide. During off-peak periods, CO2 vapor is withdrawn from the reservoir and condensed to liquid by vaporizing LNG, so that use is always efficiently made of the available refrigeration from the vaporizing LNG, and valuable peak electrical power is available when needed by using the stored energy in the CO2 reservoir (41).

Depressurization of natural gas hydrates in berea sandstone cores

Abstract: D. W. Davidsonet al. [7] were among the first to recognize significant deposits of natural gas clathrate hydrates in the Western Hemisphere. This work discusses the recovery of gas from such deposits, through laboratory measurement and modeling of a depressurization scheme. The work provides a determination of the volume of gas produced and the position of the hydrate interface, as a function of time when a hydrate-containing core is depressurized. A moving boundary model is shown to provide a satisfactory fit to hydrate dissociation measurements. Qualitative information is provided concerning hydrate formation in Berea Sandstone cores.

Fuel Science and Technology Handbook

Abstract: The focus here is on new methods and known technologies that assist in the development of unconventional worldwide fossil fuel resources comparing petroleum to other fossil fuels, such as tar sands and heavy oils, bitumen, coal, oil shale, and natural gas. The contributions contrast scientific and t

Hydrate Dissociation in Sediment

Abstract: An analytical model that describes hydrate dissociation under thermal stimulation in porous media is presented. The model views the dissociation as a process in which gas and water are produced at a moving dissociation boundary. The boundary separates the dissociated zone containing gas and water from the undissociated zone containing the hydrate. A similarity solution to the conservation equations is derived, and results are presented in graphical forms that are useful in numerical computations. In particular, heat fluxes, temperature profiles, and gas pressure distributions are presented for two cases that simulate saturated-steam and hot-water thermal stimulation. A parametric study showed that the dissociation rate is a strong function of the thermal properties of the system and the porosity of the porous medium. The energy efficiency of the dissociation process, defined as the ratio of the heating value of the gas produced relative to the heat input, was also computed. For hydrate thermal stimulation, an energy efficiency value of about nine was found, which appears encouraging for natural gas production from hydrate.

Cryogenic separation of gaseous mixtures

Abstract: In a cryogenic technique for recovering ethene from a gaseous mixture containing methane, ethane, and ethene, the gaseous mixture is passed through a chilling train having a series of dephlegmator-type exchange units (20, 24) to condense liquid rich in ethene and thane, while separating a major portion of methane and lighter gas. A multizone demethanizer (30, 34) removes condensed methane from the C2 fraction to provide a pure product economically.

Removal and destruction of volatile organic compounds from gas streams

Abstract: An apparatus and process for adsorbing volatile organic compounds, or VOCs (102) and efficiently regenerating adsorbent material in an emission control system (100). Flue gas (132), emitted from a combustion unit (130) burning an outside fuel (168) and desorbed VOCs (160), is humidified and cooled with a set of water injectors (136, 146). The resultant humidified flue gas (150) is directed through the adsorbent material in either adsorber (110) or (120), which is rapidly superheated without pressurization. A method of controlling the regeneration cycle of emission control system (100) includes at least three sensor configurations including a breakthrough sensor, a desorbed gas sensor and a flue gas temperature sensor.

Liquefaction of natural gas using process-loaded expanders

Abstract: A process for the liquefaction of natural gas is disclosed wherein expansion valves for low-level multicomponent refrigerant and liquefied gas product streams are replaced with process-loaded turboexpanders having liquid inlet streams. Each turboexpander is coupled with a compressor or pump so that expansion work extracted from a given stream is used directly to compress or pump the stream prior to cooling and expansion. The use of process-loaded turboexpanders reduces the minimum work of liquefaction and increases the liquefaction capacity of the process.

Process for purifying natural gas

Abstract: Processes are disclosed for separating water and carbon dioxide from hydrocarbon streams, e.g., natural gas, by adsorption prior to low temperature hydrocarbon processing operations, e.g., liquid natural gas recovery and nitrogen rejection. The processes employ separate adsorption zones for the water and carbon dioxide adsorption and both adsorption zones are operated with a thermal swing adsorption cycle. A product gas from the low temperature processing operation, e.g., methane, can be used as the purge gas for one or both adsorption zones and the desorbed water and carbon dioxide, along with the purge gas can be recovered and introduced into a natural gas pipeline, for example.

Well production method

Abstract: Apparatus and method for the production of methane gas from coalbed methane wells. The apparatus includes a production string having spaced side pocket mandrels supporting gas lift valves and defining with a well casing an annulus in the well running continuously without a packer from a coalbed seam to the wellhead and a lift gas injection line extending through the annulus along the production tubing string and connected into the side pocket mandrel for injecting lift gas into the production tubing string to produce well fluids and lift gas in the tubing string while simultaneously producing coalbed methane gas up the annulus. The method of the invention includes the steps of injecting lift gas through a lift gas injection line to a gas lift valve in a well production tubing string and producing well fluids along with lift gas up the tubing string while producing coalbed methane gas up the annulus.

Gas phase and catalytic ignition of methane and ethane in air over platinum

Abstract: The ignition of gas phase combustion by a heated catalytically active surface involves dynamic coupling of transport processes and chemical kinetics. Researchers have observed that surfaces with high catalytic activity require higher surface temperatures to ignite gas phase combustion, compared to nonactive surfaces, and that this difference is greatest for a stoichiometric mixture. In this work an analysis of the ignition of surface-catalyzed oxidation is developed along with an experimental technique for independently monitoring both surface and gas phase ignition such that the dynamics of these two events can be decoupled. Experiments suggest that the sharp maximum in surface temperature required for gas phase ignition observed in previous work is an artifact caused by transient heating of the surface as ignition occurs. Analysis of surface ignition was also used to investigate the kinetics of methane and ethane oxidation on platinum.

Low pollution natural gas vehicle

Abstract: A method and apparatus for reducing emissions from an internal combustion engine used for propelling a heavy land vehicle, for example, comprising a fuel supply tank for storing liquified natural gas and a fuel circuit for cooling compressed charge air to the engine with the heat of vaporization of the fuel. Under low load conditions fuel vapor from the tank can be consumed to avoid an excessive build-up of pressure; the engine is operated with a lean fuel/air mixture without cooling of the charge air to obtain low emissions. Non-methane hydrocarbon emissions are eliminated by stripping the natural gas of essentially all of the higher hydrocarbons during the liquification process.

Method and apparatus of obtaining natural gas from a maritime deposit

Abstract: The natural gas which is obtained from a maritime deposit is purified on a platform or ship and is then compressed and cooled while on the platform or ship before being delivered under pressure to a LNG tanker where liquefaction takes place by expansion. An expansion group is disposed on the tanker in order to obtain liquefied natural gas at approximately 1 bar while non-liquified residual gases are returned to the platform or ship via a return line.

Power installation using fuel cells

Abstract: A method and installation is proposed for generating electrical energy in an open circuit for a gaseous fluid, comprising a compressor unit driven by a turbine receiving the compressed fluid after its passage through an exhaust gas heat exchanger, said method and installation further comprising a power generator driven by a gas turbine, the circuit also comprising a fuel cell receiving natural gas in its anode from an external source and receiving and gaseous fluid from the compressor unit as an oxidizing agent in its cathode, the electrical power originating from both the generator and the fuel cell forming the output of the method and installation.

Cryogenic rectification process for separating nitrogen and methane

Abstract: CRYOGENIC RECTIFICATION Process For Separating Nitrogen and Methane ABSTRACT A cryogenic rectification process for the separation of nitrogen and methane wherein feed is preseparated in a high pressure column or phase separator into vapor and liquid portions, the vapor is condensed and at least partly employed as reflux for a main column, the liquid is passed into the main column at an intermediate point, and a portion of the liquid is vaporized against itself to provide additional column vapor upflow.

Heavy crude upgrading using remote natural gas

Abstract: A method of producing and upgrading crude oil in flowable form which is characterized by the steps of forming hydrogen from methane gas and hydrogenating only a portion of the crude oils and produce a less viscous bottom stream that is then admixed with the remainder of the crude to form a flowable crude and transporting the flow of crude to a refinery.

The economics of natural gas : pricing, planning and policy

Abstract: Natural gas resembles oil in fulfilling a wide variety of uses as both a source of energy and a feedstock, but the proportion of world production that is traded internationally is very much lower, and insufficient for a "world price" of gas to be established. This book addresses the issues of how the "economic price" of gas is determined. These are illustrated with estimates of the costs of exploration and production of gas, and of the benefits to be derived from its use in various economic sectors for a number of Third World countries. The book also presents a detailed case-study of the development of gas pricing in Bangladesh, and an analytical framework for the development of a formal "gas planning model" that could be applied to the cases of actual countries contemplating the development of gas use in the future.

Organic waste fuel combustion system integrated with a gas turbine combined cycle

Abstract: The invention comprising an organic waste fuel combustion and tempering gas flow control system integrated with a gas turbine combined cycle steam generating plant. The gas turbine exhaust, wherein the oxygen content is partially consumed is used to dry and support combustion of an organic fuel high in moisture content after said fuel has been dewatered and pelletized. A portion of the gas turbine exhaust gas stream dries the pelletized waste fuel while a parallel portion of the gas turbine hot gas stream is used to support combustion and furnish oxygen in the ignition zone of the pelletized waste combustor. The drying stream also tempers secondary combustion gas temperature. The two gas streams are combined downstream of the combustion zone. The regenerated combined stream is then utilized in a steam generating section to generate steam. The gas turbine exhaust flow provides the mass flow and heat required for drying and combusting the pelletized waste fuel and the heat input from the pellet firing system regenerates the gas turbine exhaust gas stream. The pellet combustion process is maintained at temperature levels which avoid formation of deleterious products of combustion during the incineration process.

Noble gas and methane partitioning from ground water: An aid to natural gas exploration and reservoir evaluation

Abstract: The partitioning of noble gases and methane from oil-field brines can provide valuable information about the redistribution of gas-phase constituents. The alterations in fluid compositions produced by closed-system phase changes are predictable, with pronounced differences from original compositions. If these alterations commonly occur in sedimentary basins, then a new aid for natural-gas exploration and reservoir evaluation can be developed.