Abstract: A gas-liquid mixing vessel utilizes an axial flow, down-pumping impeller in a draft tube to create vortex development so as to draw gas from the overhead in a body of recirculating liquid. A surge tank is used to accommodate volume changes in the vessel, and a liquid level control feature, in which the gas phase pressures in the mixing vessel and the surge tank are adjusted, is used to maintain the liquid level in the mixing vessel at a desired level for proper vortex development.

Abstract: Wet feed air to, or high purity nitrogen from, a pressure swing adsorption system is dried in a dryer membrane system preferably operated with a countercurrent flow path. Drying is enhanced by the use of a purge gas on the permeate side of the membrane, with waste gas from the pressure swing adsorption system or a portion of the dry, high purity nitrogen product gas being used as purge gas.

Abstract: The incorporation of a small amount of metal fluoride or fluosilicate into the refractory fibrous insulating board lining of an aluminum refining vessel prevents the infiltration of the internal voids of said lining by molten aluminum.

Abstract: Permeable membranes comprised predominantly of specifically defined polyester of 4,4'-(1H-alkylidene)bis[2,3,6-trialkylphenol] and aromatic dicarboxylic acids. The invention also pertains to the novel permeation processes for recovery of an oxygen/nitrogen or carbon dioxide/methane or helium/methane component from a mixture of said component with other components in the mixture.

Abstract: Composite membranes are prepared by depositing a separation layer on an asymmetric support layer. The separation layer has a selectivity equal to or greater than that of the material of the asymmetric support layer for a desired gas separation. The support layer is desirable produced in non-asymmetric form, and exposed to an elevated temperature approaching the glass transition temperature of the support layer material under non-swelling conditions to modify the structure thereof to create asymmetry therein, before or after the deposition of the separation layer, and to increase its compaction resistance and collapse pressure. Such desirable properties are conveniently achieved on a repeatable basis, enhancing the uniformity and reliability of the treated support layer and of composite membranes produced therefrom, for use in gas separation operations.

Abstract: Process for the dehydration of gases using composite permeable membranes, preferably hollow fiber composite membranes comprised of a porous support coated with an ultrathin layer of a defined sulfonated polysulfone or sulfonated polyether ketone. The processes also contemplate the use of a sweep or purge gas on the water-enriched permeate side of the composite membrane to increase the efficiency of the dehydration process.

Abstract: High gas flow requirements of large size lines are conveniently provided by a series of high pressure tubes connected to header means adapted to control the storage and distribution of gas to the lines at desired flow rates for relatively short periods of time. Gas thus supplied can conveniently be used as a propelling gas stream for the in-situ cleaning of large size lines under high exit velocity conditions requiring the supply of gas at a high flow rate not conveniently supplied by conventional pumpers.

Abstract: Sulfonated hexafluoro bis-A-polysulfone membranes of polymers and copolymers having the repeat unit of the structure; ##STR1## in the polymer molecule that exhibit improved permeation and separation characteristics and processes for the use thereof for separation of a component from a fluid mixture of said component in admixture with other components.

Abstract: On-site membrane systems are used for air separation to produce a low purity nitrogen stream and for purifying impure hydrogen, the nitrogen and hydrogen being passed to a catalytic combustion system in which the oxygen content of the nitrogen stream is reacted with said hydrogen to reduce the residual oxygen content of the nitrogen in a final purification operation to produce high purity nitrogen. Pressure swing adsorption systems can be employed in place of the membrane systems for particular applications, and a cryogenic system can be employed for said hydrogen purification.

Abstract: Feed air to a prepurifier adsorption system/cryogenic air separation system for dry, high purity nitrogen and/or oxygen production is dried in a membrane dryer preferably characterized by a countercurrent flow path. Drying is enhanced by the use of purge gas on the permeate side of the membrane dryer, which adsorption system or cryogenic air separation system product or waste gas, dried feed air or ambient air being used as purge gas.

Abstract: High purity nitrogen from an air separation membrane/deoxo system is dried in a membrane dryer unit preferably operated with a countercurrent flow path in the membrane bundle. Drying is enhanced by the use of purge gas on the permeate side of the membrane dryer unit, with feed air, product nitrogen or waste gas from the air separation membrane system being used as purge gas.

Abstract: A gas-liquid mixing process and apparatus having a vessel with an axial flow down-pumping impeller in a draft tube has gas ingestion tubes extending into a body of liquid from a hollow portion of the impeller shaft or other fluid communication means with the overhead gas in the vessel. Upon gas-liquid mixing at liquid levels that interfere with vortex development by the impeller, gas is drawn from the overhead through the ingestion tubes into the body of liquid.

Abstract: A feed gas stream is introduced directly into a recirculating liquid stream so as to facilitate formation and maintenance of gas bubbles in a dispersed form in a recirculating gas bubble-liquid mixture. By the maintaining of a gas-liquid interface and overhead gas phase in conjunction with a quiescent zone of liquid apart from the portion of liquid in which said mixture is maintained in a recirculating flow condition, the loss of appreciable amounts of gas to the overhead gas phase is avoided.

Abstract: Gas samples withdrawn from within a reactor vessel, as well as from the feed gas thereto, are passed to gas analyzers for particular components or impurities desired to be measured. The response time of the reactor analysis system employed is advantageously minimized by the elimination of dead gas space upon the closing of control valves and the provisions for rapid purging of the system or of individual gas analyzer feed lines.

Abstract: Composite membranes are prepared by depositing a separation layer on an asymmetric support layer. The separation layer has a selectivity equal to or greater than that of the material of the asymmetric support layer for a desired gas separation. The support layer is desirably produced in non-asymmetric form, and exposed to an elevated temperature approaching the glass transition temperature of the support layer material under non-swelling conditions to modify the structure thereof to create asymmetry therein, before or after the deposition of the separation layer, and to increase its compaction resistance and collapse pressure. Such desirable properties are conveniently achieved on a repeatable basis, enhancing the uniformity and reliability of the treated support layer and of composite membranes produced therefrom, for use in gas separation operations.

Abstract: Feed gas is introduced into the bores of a helically wound hollow fiber membrane cartridge containing hollow fibers of essentially uniform active lengths. Permeate gas flow is maintained countercurrent to the feed and raffinate gas entrance and exit axis, respectively, while the directional flow axis of permeate withdrawal can be at a substantial angle to the helically wound hollow fiber membrane surface. Complete radial mixing of the permeate stream on the outer, permeate side and essentially no axial mixing on either the permeate or the raffinate side of the hollow fiber membrane cartridge are maintained.

Abstract: In the separation of gases in a membrane system, degradation of membrane permeability is prevented by passing the feed gas mixture through a bed of adsorbent material, preferably activated carbon, to adsorb the heavier hydrocarbon contaminants responsible for degradation without removal of lighter hydrocarbons.

Abstract: Two or more different permeable membranes capable of separating different components of a fluid mixture are used to farbicate hollow fiber multicomponent cells and permeator modules.

Abstract: A method for enhancing the long term performance of gas separation membranes. The permeable membranes are heated at a moderate temperature of from about 50.degree. C. to 140.degree. C. Use of this method enables restoration and reclamation of permeable membranes that have suffered degradation in performance in gas separation processes.

Abstract: Enriched oxygen from a pressure swing adsorption system and air are blended to provide oxygen enriched air of desired purity, particularly for use at flow rates between those for which liquid oxygen and on-site cryogenic air separation plants are desirable.