Abstract: Natural gas liquids (NGLs) are recovered by cooling and partial condensation of a purified natural gas feed wherein a portion of the necessary feed cooling and condensation duty is provided by expansion and vaporization of condensed feed liquid after methane stripping, thereby yielding a vaporized NGL product. Additional refrigeration for feed cooling is provided by vaporizing methane-stripped liquid, which in turn provides vapor boilup for the stripping step. Recompression and cooling of the vaporized NGL product can be utilized if a liquid product is required.

Abstract: Oxygen is separated from air by a high temperature ion transport membrane which is integrated with a gas turbine system for energy recovery from the membrane nonpermeate stream. Air is compressed, heated in a first heating step, and passed through the feed side of a mixed conductor membrane zone to produce a high purity oxygen product on the permeate side of the membrane zone. Nonpermeate gas from the membrane zone is heated in a second heating step and passed through a hot gas turbine for power recovery. Water is added to the nonpermeate gas prior to the hot gas turbine to increase mass flow to the turbine and thus balance the mass flows of the air feed compressor and the expansion turbine.

Abstract: Oxygen is recovered from a heated, compressed, oxygen-containing feed gas by selective permeation of oxygen through an ion transport membrane separation system and the hot, pressurized non-permeate gas is passed through an expansion turbine to recover power for compressing the feed gas and optionally generating electric power. Membrane performance and process heat recovery are enhanced by the addition of water to selected process streams. Steam raised by process heat is used to sweep the permeate side of the membrane to increase the oxygen permeation rate. The injection of partially or fully vaporized water into the expansion turbine inlet gas recovers process heat and increases mass flow to the turbine.

Abstract: Hydrocarbons are recovered from the product purge gas in an alkene polymerization process by absorption of heavier hydrocarbons from the purge gas by an intermediate hydrocarbon stream to yield a vapor rich in inert gas and alkene monomer. Alkene monomer is condensed at low temperatures from the inert gas, flashed and vaporized to provide refrigeration for the condensation step, and recycled to the polymerization process. The intermediate hydrocarbon from the absorption step is recycled to the polymerization process. Optionally a portion of the inert gas is reused for purge gas.

Abstract: Nitrogen oxides are removed from the exhaust of an internal combustion engine which operates on a methane-containing fuel by reacting the nitrogen oxides and oxygen in the exhaust gas with a controlled amount of methane in the presence of a reducing catalyst. The catalyst preferably comprises a crystalline zeolite having a silicon to aluminum ratio of equal to or greater than about 2.5 which is prepared from a non-acid zeolite which is ion exchanged with a cation selected from the group consisting of cobalt, nickel, iron, chromium, and manganese. Methane for the reaction is provided as a portion of the methane-containing fuel. Carbon monoxide present in the exhaust gas is converted to carbon dioxide simultaneously with the reduction of nitrogen oxides.

Abstract: Oxygen is separated from air by a high temperature ion transport membrane which is integrated with a gas turbine system for energy recovery from the membrane nonpermeate stream. Air is compressed, heated in a first heating step, and passed through the feed side of a mixed conductor membrane zone to produce a high purity oxygen product on the permeate side of the membrane zone. Nonpermeate gas from the membrane zone is heated in a second heating step and passed through a hot gas turbine for power recovery. The operating temperatures of the membrane zone and the expansion turbine are independently maintained by controlling the rate of heat addition in the first and second heating steps, whereby the membrane zone and expansion turbine are thermally delinked for maximum oxygen recovery efficiency.

Abstract: A fluid mixture is separated by distillation in a two column system in which the feed is prefractionated in a first column having at least one separation stage above the feed and the prefractionator bottoms provides feed to a second column operating at a lower pressure. Cooling for condensing the overhead vapor of the first column is provided by heat exchange with flashed prefractionator bottoms or with an intermediate fluid in the second column. The two-column system is readily combined with a high pressure column in a three-column distillation system for separating air which is particularly useful for integration with a gasification combined cycle combustion turbine system. Optionally, three nitrogen products can be produced at three different pressures.

Abstract: A composite semipermeable membrane comprising microporous adsorbent material supported by a porous substrate is utilized to separate hydrogen-hydrocarbon mixtures and a sweep gas comprising some of the same hydrocarbons is passed across the low pressure side of the membrane to enhance hydrocarbon permeability. Methane is an effective sweep gas which promotes the permeation of heavier hydrocarbons even when methane is present in the membrane feed.

Abstract: Improved composite semipermeable membranes including microporous carbonaceous adsorptive material supported by a porous substrate for use in separating multicomponent gas mixtures in which certain components in the mixture adsorb within the pores of the adsorptive material and diffuse by surface flow through the membrane to yield a permeate stream enriched in these components. Methods for making the improved composite membranes are described including one or more oxidation steps which increase the membrane permeability and selectivity.

Abstract: A closed-loop mixed refrigerant cycle provides efficient low-level refrigeration for recovering ethylene from a mixed gas feed. Compressed mixed refrigerant vapor is condensed at -20.degree. F. to -50.degree. F. and is subcooled to -175.degree. F. to -225.degree. F. by indirect heat exchange with cold H.sub.2, methane, and expander streams from elsewhere in the ethylene plant. A portion of the subcooled refrigerant may be flashed to provide additional subcooling of the main mixed refrigerant stream. Subcooled mixed refrigerant is subsequently flashed to provide very low temperature level refrigeration for feed condensation and demethanizer overhead condenser duties. The invention allows advantageous operation of the feed chilling train at pressures between 150 and 400 psia.

Abstract: Oxygenated acetyl compounds ethylidene diacetate, acetic acid, acetic anhydride, acetaldehyde, and methyl acetate are produced directly from synthesis gas and dimethyl ether in a catalyzed liquid phase reaction system. The inclusion of carbon dioxide in the synthesis gas in selected amounts increases the overall yield of oxygenated acetyl compounds from the reactant dimethyl ether. When methanol is included in the reactor feed, the addition of carbon dioxide significantly improves the molar selectivity to ethylidene diacetate.

Abstract: A method for white liquor oxidation in a kraft mill utilizes a two-stage selective oxidation system in which the first stage is operated to remove sulfide while the second stage is operated to oxidize a significant fraction of the remaining oxidizable sulfur compounds to sulfate. The resulting selectively oxidized white liquor products are used as alkali sources for various process steps in the mill. Optionally, white liquor can be oxidized in a single stage to convert a significant fraction of the oxidizable sulfur compounds to sulfate. Methods for controlling the selective oxidation process are disclosed.

Abstract: Refrigeration is provided in an ethylene recovery plant by an open-loop mixed refrigeration cycle which utilizes components present in the ethylene-containing feed gas as the mixed refrigerant. Refrigeration is provided by subcooled mixed refrigerant at -175.degree. to -225.degree. F. for the demethanizer overhead condenser and for initial cooling and condensation of the ethylene-containing feed gas. Overall ethylene recoveries of up to 99.9% can be achieved at reduced power consumption compared with conventional ethylene recovery cycles. In addition, significant capital savings can be realized due to the simplification of equipment with the open-loop mixed refrigerant cycle, which can be operated advantageously at pressures between 150 and 400 psia.

Abstract: An improved method of chemical recovery from kraft black liquor is disclosed in which the heat generated by controlled oxidation of the liquor is utilized to reduce the viscosity and net heating value of the liquor which allows the firing of a more concentrated liquor in the recovery boiler. Net steam recovery is increased for a given black liquor feed rate. Alternatively, the firing of liquor having a higher solids concentration is possible, which increases the throughput of the recovery boiler.

Abstract: Nitrogen oxides and carbon monoxide are removed from the exhaust of an internal combustion engine which operates on a methane-containing fuel by reacting the carbon monoxide, nitrogen oxides, and oxygen in the exhaust gas with methane in the presence of a catalyst comprising a crystalline zeolite having a silicon to aluminum ratio of equal to or greater than about 2.5 which is exchanged with a cation selected from the group consisting of cobalt, nickel, iron, chromium, rhodium, gallium, and manganese. Methane for the reaction is provided as a portion of the methane-containing fuel.

Abstract: Volatile organic compounds and water vapor are recovered from a low-boiling gas by compressing the gas to an elevated pressure and cooling the gas in stages to condense volatile components and water while avoiding freezing in the system. Operating the system at an elevated pressure increases condensation efficiency, reduces the number of stages required, and minimizes operating problems to avoid freezing.

Abstract: High-purity oxygen is recovered from air by a high-temperature ion transport membrane system comprising two or more stages in which each stage operates at a different feed side to permeate side pressure ratio. Operation of the system in multiple stages at controlled pressure ratios produces oxygen at a lower specific power consumption compared with single-stage operation.

Abstract: A composite semipermeable membrane comprising microporous adsorbent material supported by a porous substrate is operated in series with a pressure swing adsorption (PSA) system and the PSA reject gas is used as a sweep gas to improve membrane performance. The integrated membrane-PSA system is particularly useful for recovering high-purity hydrogen from a mixture of hydrogen and hydrocarbons, and is well-suited for integration with a steam-methane reformer.

Abstract: Recovery of hydrogen from hydrogen-containing gas mixtures by pressure swing adsorption is increased by utilizing an adsorbent membrane to concentrate hydrogen in the pressure swing adsorption reject gas and recycling the resulting hydrogen-enriched stream to the feed of the pressure swing adsorption system. Lower compression requirements are realized compared with the use of polymeric membranes for the same service because the hydrogen-enriched stream is recovered from the adsorbent membrane as nonpermeate at essentially the membrane feed pressure. Simultaneous permeation of carbon dioxide and methane occur in the adsorbent membrane, which can be operated at feed pressures as low as 5 psig when hydrogen is used as a sweep gas.

Abstract: Improved composite semipermeable membranes including microporous carbonaceous adsorptive material supported by a porous substrate for use in separating multicomponent gas mixtures in which certain components in the mixture adsorb within the pores of the adsorptive material and diffuse by surface flow through the membrane to yield a permeate stream enriched in these components. Methods for making the improved composite membranes are described including one or more oxidation steps which increase the membrane permeability and selectivity.