Abstract: A method for generating electric power from natural gas or the like that has a low Btu value and a high nitrogen content. The method involves a membrane separation step to remove a portion of the nitrogen from the gas. The upgraded gas is used as fuel for a turbine or other driver, which provides mechanical power to drive an electric power generator.

Abstract: A process for treating gas streams containing hydrogen and hydrocarbons. The process includes a membrane conditioning step to remove C.sub.5 -C.sub.8 hydrocarbons, followed by a selective adsorption or membrane separation step to separate hydrogen from methane. The membrane conditioning step uses a membrane selective for C.sub.5 -C.sub.8 hydrocarbons over hydrogen.

Abstract: A treatment process for a hydrogen-containing off-gas stream from a refinery, petrochemical plant or the like. The process includes three separation steps: condensation, membrane separation and hydrocarbon fraction separation. The membrane separation step is characterized in that it is carried out using a polymeric separation membrane that is selective in favor of hydrocarbons, including methane, over hydrogen, so that the hydrogen-enriched stream is delivered at high pressure.

Abstract: A process train for treating a gas stream containing methane, nitrogen, and at least one of water vapor, acid gas, C.sub.3+ hydrocarbons and aromatic hydrocarbons, the gas stream typically, but not necessarily, being natural gas. The treatment train includes separation of methane from nitrogen by means of membranes that preferentially permeate methane and reject nitrogen. Preferred processes include both a dehydration step and an NGL removal step to treat the gas before it passes to the methane/nitrogen membrane separation step. The process train can also include additional steps, such as an acid gas removal step, or a cryogenic methane/nitrogen separation step.

Abstract: A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.

Abstract: A process for separating chlorine from other low-boiling components of a gas-phase mixture. The invention involves three separation steps: condensation, flash evaporation and membrane separation. The steps are integrated together in such a way as to provide a good separation between the components, and to avoid creation of secondary streams that need additional treatment. The invention is particularly useful for treatment of gas streams from chlor-alkali processes.

Abstract: An improved, membrane-based method of treating gas evolved during natural gas liquids (NGL) stabilization, to separate the very light hydrocarbon gases, methane in particular, from the heavier hydrocarbons. The membrane acts as a demethanizer and establishes a vapor/liquid equilibrium during phase separation that is different than would otherwise obtain. This can increase NGL production and reduce the weight of C.sub.3+ hydrocarbons in the off-gas from the stabilizing phase separators.

Abstract: An improved, membrane-based method of treating gas evolved during gas/oil separation, to separate the very light hydrocarbon gases, methane in particular, from the heavier hydrocarbons. The membrane acts as a demethanizer and establishes a vapor/liquid equilibrium during phase separation that is different than would otherwise obtain. This can increase oil production and reduce the weight of C.sub.4+ hydrocarbons lost in the associated gas.

Abstract: A process for recovering organic components from gas streams by condensation. The process uses a semipermeable separation membrane as an expansion device to provide cooling for condensation.

Abstract: A process for separating two low-boiling components of a gas-phase mixture. The invention involves three separation steps: condensation, flash evaporation and membrane separation. The steps are integrated together in such a way as to provide a good separation between the components, and to avoid creation of secondary streams that need additional treatment. The invention is particularly useful for separation of low molecular weight organic compounds from other gases.

Abstract: A process for separating hydrocarbon gases of low boiling point, particularly methane, ethane and ethylene, from nitrogen. The process is performed using a membrane made from a super-glassy material. The gases to be separated are mixed with a condensable gas, such as a C.sub.3+ hydrocarbon. In the presence of the condensable gas, improved selectivity for the low-boiling-point hydrocarbon gas over nitrogen is achieved.

Abstract: A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.

Abstract: A membrane separation process combined with a cryogenic separation process for treating a gas stream containing methane, nitrogen and at least one other component. The membrane separation process works by preferentially permeating methane and the other component and rejecting nitrogen. The process is particularly useful in removing components such as water, carbon dioxide or C.sub.3+ hydrocarbons that might otherwise freeze and plug the cryogenic equipment.

Abstract: Improved processes for treating gas streams containing hydrogen sulfide and carbon dioxide, particularly natural gas streams. The processes rely on the availability of a membrane that maintains high hydrogen sulfide/methane selectivity and adequate hydrogen sulfide/carbon dioxide selectivity when measured with multicomponent gas mixtures at high pressure. The processes have three steps: an acid gas removal step, to remove both hydrogen sulfide and carbon dioxide from the primary gas stream; a membrane fractionation step, to separate hydrogen sulfide from carbon dioxide and create a highly hydrogen-sulfide-concentrated fraction; and a sulfur-fixing step.

Abstract: Improved processes for treating gas streams containing hydrogen sulfide and carbon dioxide, particularly gas streams from fossil fuel gasification processes. The processes rely on the availability of a membrane that maintains high hydrogen sulfide/methane selectivity and adequate hydrogen sulfide/carbon dioxide selectivity when measured with multicomponent gas mixtures at high pressure. The processes have three steps: an acid gas removal step, to remove both hydrogen sulfide and carbon dioxide from the primary gas stream; a membrane fractionation step, to separate hydrogen sulfide from carbon dioxide and create a highly hydrogen-sulfide-concentrated fraction; and a sulfur-fixing step.

Abstract: A membrane process for separating chlorine from chlorine-containing gas streams is disclosed. The process employs a permselective membrane that is selective to chlorine and is stable in the long-term presence of chlorine. The process can be used to treat tail-gas from chlor-alkali plants, for example.

Abstract: Improved membranes and improved membrane processes for treating gas streams containing hydrogen sulfide, carbon dioxide, water vapor and methane, particularly natural gas streams. The processes rely on the availability of two membrane types, one of which has a hydrogen sulfide/methane selectivity of at least about 40 when measured with multicomponent gas mixtures at high pressure. Based on the different permeation properties of the two membrane types, optimized separation processes can be designed.

Abstract: Improved processes for treating gas streams containing hydrogen sulfide, carbon dioxide, water vapor and methane, particularly natural gas streams. The processes rely on the availability of two membrane types, one of which has a hydrogen sulfide/methane selectivity of at least about 40 when measured with multicomponent gas mixtures at high pressure. Based on the different permeation properties of the two membrane types, optimized separation processes can be designed. The membrane separation is combined with non-membrane treatment of the residue and/or permeate streams.

Abstract: Improved membranes and improved membrane processes for treating gas streams containing hydrogen sulfide and methane, plus water vapor, carbon dioxide or both. The processes rely on the availability of two membrane types, one of which has a high hydrogen sulfide/methane selectivity and a high water vapor/methane selectivity, when measured with multicomponent gas mixtures at high pressures. Based on the different permeation properties of the two membrane types, optimized separation processes can be designed. In favorable cases, the processes can simultaneously dehydrate the gas stream and remove the hydrogen sulfide to very low levels.