Abstract: This invention comprises an improved process for generating Nitrogen from air in which a vacuum is placed on the permeate side of a gas separation membrane, usually of the polysulfone type, resulting in highly enhanced flow rates and nitrogen purity sufficient for oil and gas pipeline repair use and for use in grain silos.

Abstract: Novel polyimide gas separation membranes and the process of using such membranes to separate gases are disclosed. The polyimides are formed from rigid aromatic dianhydrides and aromatic diamines that contain sulfonic acid, salified sulfonic acid, or sulfonic ester groups. Methods of preparing improved composite gas separation membranes from the sulfonated polyimides of this invention are disclosed.

Abstract: An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

Abstract: The present invention presents a new class of multicomponent metallic oxides which are particularly suited toward use in fabricating components used in solid-state oxygen separation devices. The compositions of the present invention are represented by the formula Ln.sub.x A'.sub.x' A".sub.x" B.sub.y B'.sub.y' B".sub.y" O.sub.3-z, wherein Ln is an element selected from the f block lanthanides, A' is selected from Group 2, A" is selected from Groups 1, 2 and 3 and the f block lanthanides, and B,B',B" are independently selected from the d block transition metals, excluding titanium and chromium, wherein 0.ltoreq.x<1, 0<x'<1, 0.ltoreq.x"<1, 0<y<1.1, 0<y'<1.1, 0<y"<1.1, x+x'+x"=1.0, 1.1>y+y'+y">1.0 and z is a number which renders the compound charge neutral wherein such elements are represented according to the Periodic Table of the Elements adopted by IUPAC.

Abstract: Membrane separation methods and systems separate gaseous mixtures into purified component gases thereof. Purified oxygen gas (60-90% purity), for example, may be derived from ambient air in an efficient manner. Systems and methods are provided by which at least three permeator stages are used while requiring less than one compressor per stage. Energy requirements are reduced and product purity as a function of energy requirements is improved.

Abstract: A separation membrane useful for gas separation, particularly separation of C.sub.2+ hydrocarbons from natural gas. The invention encompasses the membrane itself, methods of making it and processes for using it. The membrane comprises a polymer having repeating units of a hydrocarbon-based, disubstituted polyacetylene, having the general formula: ##STR1## wherein R.sub.1 is chosen from the group consisting of C.sub.1 -C.sub.4 alkyl and phenyl, and wherein R.sub.2 is chosen from the group consisting of hydrogen and phenyl. In the most preferred embodiment, the membrane comprises poly(4-methyl-2-pentyne) ?PMP!. The membrane exhibits good chemical resistance and has super-glassy properties with regard to separating certain large, condensable permeant species from smaller, less-condensable permeant species. The membranes may also be useful in other fluid separations.

Abstract: A composite membrane made of an asymmetric porous support and an ultrathin layer having a thickness of less than 100 nm is provided. A method of making the membrane and method for carrying out gas separations using the membrane are also provided.

Abstract: The present invention relates to novel solid state mixed conductor membranes and their use for separating oxygen from oxygen-containing feeds at elevated temperatures. The membranes comprise a multicomponent metallic oxide of substantially cubic perovskite structure, stable in air over the temperature range of 25.degree.-950.degree. C., having no connected through porosity wherein the membrane is of a composition represented by the formula ?A.sub.1-x A'.sub.x !?Co.sub.1-y-z B.sub.y B'.sub.z !O.sub.3-.delta., where A.ident.Ca, Sr, Ba, and mixtures thereof; A'.ident.La, Y, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U, and mixtures thereof; B.ident.Fe, Mn, Cr, V, Ti, and mixtures thereof; B'.ident.Cu, Ni, and mixtures thereof; .about.0.0001.ltoreq..times..ltoreq..about.0.1; .about.0.002.ltoreq.y<0.05; .about.0.0005.ltoreq.z.ltoreq..about.0.3; .delta. is determined by the valence of the metals.

Abstract: A macroporous polymeric adsorbent is used to remove oil mist and oil vapors from compressed air produced by an oil-lubricated air compressor prior to feeding the compressed air to an air separation membrane system. The macroporous polymeric adsorbent, previously known only for its ability to extract low molecular weight volatile organic compounds from liquids and gases, retains its ability to extract the oil for extended periods of time and outperforms the commonly used activated carbon of the prior art.

Abstract: A hollow fiber membrane module and its method of manufacture are disclosed wherein the module is fabricated utilizing superior hollow fiber materials, namely high molecular weight (i.e. molecular weight>500,000 Daltons) polymers. In a preferred embodiment, the hollow fibers are fabricated from ultra-high molecular weight polyethylene (UPE). An array of UPE hollow fiber membranes is contacted with an extrusion of molten thermoplastic polymer at a contact temperature which is higher than the UPE membrane polymer. This high temperature application of sealing polymer does not collapse or otherwise deform the lumen of the hollow fiber, while assuring that the polymer can thus be applied with sufficiently low viscosity to provide adequate penetration around the individual fibers of the array to form an integral seal thereabout.

Abstract: The invention produces essentially pure nitrogen from air by an intermittent, automatic, and unattended process. Air is filtered, compressed and enters a nitrogen module containing a permeable membrane that selectively separates nitrogen from the air and discharges oxygen and other gases. Automated temperature and pressure controls allow the permeable membrane to separate air components. A discharge hose allows use of the nitrogen product for a variety of intermittent applications including vending for inflation of tires, filling portable nitrogen vessels, and use in manufacturing processes.

Abstract: This invention relates to a method of and apparatus for separating component gases in a gas mixture employing a glassy polymer membrane at temperatures of 5.degree. C. or less so as to achieve superior separation of gas components.

Abstract: The present invention concerns a polyester gas separation membrane which is obtained by the interfacial polymerization of benzenetricarbonyl trihalide or benzene tetracarbonyl tetrahalide in a water-insoluble organic solvent in one phase and a variety of polyfunctional phenols present as the di- or tri-salt in a mixture of water and phase transfer agent and a water-soluble organic solvent in the second phase. The present invention also includes the polyester membrane itself, its methods of preparation and the use of the membranes to separate gas mixtures, such as carbon dioxide and methane, helium and methane and the like.

Abstract: A method for separating gases with enhanced selectivity comprises causing a mixture of gases to be separated to flow through a molecular sieving membrane (MSM), at cryogenic temperatures.

Abstract: A nitrogen generation control system and method are provided for controlling levels of nitrogen and oxygen in a controlled atmosphere within a container for perishable goods. The nitrogen generation control system has a nitrogen generator that controllably generates an amount of nitrogen, while releasing oxygen as an off gas. The nitrogen is injected into the container to create a controlled environment. A sample analyzer subsystem is connected to the container to extract a sample of gases from the controlled environment and analyze the oxygen content. The control system further includes a cascaded, dual control loop controller coupled to the nitrogen generator and sample analyzer subsystem. The controller has a nitrogen generation control loop to control the amount of nitrogen generated by the nitrogen generator in response to variation between the oxygen released during nitrogen generation and a reference amount of oxygen.

Abstract: There are provided an ozone water treatment method by comprising the steps of injecting an ozone-containing gas into pure water to prepare ozone water, supplying the ozone water to use point(s) for treatment of materials to be treated, and circulating for reuse or discharging the ozone water after use, which comprises disposing a deozonizing apparatus, the inside of which is divided into an ozone water passing zone and a reduced pressure zone by a diaphragm, at the downstream side of the use point(s), supplying the ozone water after use to the ozone water passing zone of the deozonizing apparatus, and removing residual ozone and residual oxygen in the ozone water after use by contacting the water with the reduced pressure zone through the diaphragm and an apparatus utilized in the ozone treatment method.

Abstract: Polymeric gas separation membranes having a separating layer with a high entropic effect are disclosed. Such membranes may provide enhanced gas separation properties for polymeric membranes. A process for making improved gas separation membranes is also disclosed.

Abstract: A planar, solid-state electrochemical oxygen sensor having a substrate, conductive strips deposited on the substrate, and a dielectric layer insulating portions of the conductive strips except those portions which define a working electrode and at least one second electrode. The working electrode may be defined by an open printed region of the dielectric, or by a needle-punched or laser-burned hole or opening in the dielectric which exposes a small region of one of the conductive strips. A solid electrolyte contacting the electrodes is covered by a semipermeable membrane which may comprise an acrylonitrile butadiene copolymer or an acrylate-based copolymer. A sample chamber is defined by the membrane, a cover member, and a gasket therebetween, and has a volume of from about 1 to about 2 .mu.m. The gasket is formulated from the highly cross-linked polymerization product of epichlorohydrin. All sensor components are selected such that a sensor operable for at least 2 days under normal conditions is produced.

Abstract: Essentially pure nitrogen gas is produced from air and stored by an intermittent, automatic, and unattended process that is compact and self contained. Air is first filtered, compressed and enters a nitrogen module containing a permeable membrane that selectively separates nitrogen from the air and discharges oxygen and other gases. The nitrogen gas then flows into a vessel for storage. The apparatus is enclosed in a housing where automated temperature and pressure controls allows the permeable membrane to separate air components. A discharge hose allows use of the nitrogen product for a variety of intermittent applications including vending for inflation of tires, filling portable nitrogen vessels, and use in other processes needing intermittent and automatic manufacture of nitrogen gas.

Abstract: A method and apparatus for producing liquid nitrogen from air comprising a gaseous mixture of about 78% by volume of nitrogen, about 21% by volume of oxygen, less than 1.0% by volume of argon, and small amounts of carbon dioxide, water vapour, and other trace elements and compounds comprise an extractor that extracts portions of the oxygen, carbon dioxide, and water vapour so as to produce a nitrogen-rich gaseous mixture comprising about 90% to about 99% by volume of nitrogen, about 10% to about 1% by volume of oxygen, and no more than trace amounts of carbon dioxide, water vapour, and other elements and compounds. A nitrogen recycle compressor compresses the nitrogen-rich gaseous mixture to a specified pressure.

Abstract: Air is compressed in an air compressor and cooled in an air cooler whereafter the impurities which have condensed out are removed. The air is subsequently reheated in a heat exchanger which is connected on the hot air side between the air compressor and the air cooler. The reheated air is passed through a plurality of membrane-type nitrogen separators, whereby the permeate of the last separator is constituted by nitrogen of the desired purity. The concentrate of this separator is recirculated to the suction side of the air compressor. The output control of the apparatus can be effected by means of an air feedback line which branches off before the heat exchanger and leads to the suction side of the air compressor. The flow through the air feedback line can be controlled by a valve which operates in dependence on the outlet pressure of the air compressor.

Abstract: The present invention relates to surface catalyzed ion transport membranes which demonstrate superior oxygen flux. The membranes comprise a dense multicomponent metallic oxide layer having a first surface and a second surface wherein the first surface is coated with a catalyst such as a metal or an oxide of a metal selected from Groups II, V, VI, VII, VIII, IX, X, XI, XV and the F Block lanthanides of the Periodic Table of the Elements. One or more porous layers formed from a mixed conducting multicomponent metallic oxide or a material which is not mixed conducting under process operating conditions may be formed contiguous to the second surface of the dense layer. The claimed membranes are capable of separating oxygen from oxygen-containing gaseous mixtures.

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: Oxygen is separated from a feed air stream to produce enriched oxygen permeate and oxygen depleted retentate gas. At least first and second process stages, arranged in series, each include a solid electrolyte membrane separating gas chambers with a retentate side in the former and a permeate side in the latter, a cathode connected to the retentate side, and an anode connected to the permeate side. Feed gas is introduced into a first gas chamber of the first process stage. The cathode and anode of the first process stage are electrically energized to drive oxygen from the feed gas in the first gas chamber through the electrolyte membrane at a first flux into a second gas chamber. Oxygen-depleted retentate gas from the first process stage is delivered to a third gas chamber of the second process stage. Similarly, the cathode and anode of the second process stage are electrically energized by a current less than that of the first process stage and at a greater voltage.

Abstract: Process and apparatus for the separation of at least one gas from an entering gaseous mixture (1), of the type in which a membrane separation is conducted with at least two successive membrane separators in the following manner: the entering mixture is passed through a first membrane separator (2) operating at a first operating temperature and all or a portion of the residual mixture (5) from this first membrane separator is passed through a second membrane separator (3) operating at a second operating temperature. A mixture enriched in the gas is obtained from the permeate outlet (6, 4) of each of these two separators. Two separators are used whose selectivities for the gas are different. These may be membranes of different type, or membranes of the same type, if the first operating temperature is different from the second operating temperature.

Abstract: The present invention relates to surface catalyzed ion transport membranes which demonstrate superior oxygen flux. The membranes comprise a porous mixed conducting multicomponent metallic oxide layer having a first surface onto which a catalyst is deposited and a second surface which is contiguous with a dense mixed conducting multicomponent metallic oxide layer. Suitable catalysts to be deposited onto the porous mixed conducting layer include one or more metals or oxides of metals selected from Groups II, V, VI, VII, VIII, IX, X, XI, XV and the F Block lanthanides of the Periodic Table of the Elements. The claimed membranes are capable of separating oxygen from oxygen-containing gaseous mixtures.

Abstract: A deaeration method for eliminating dissolved gases from a liquid product, which method involves low initial cost and running cost, compact equipment, and simple arrangement to accomplish the deaeration. For the method to eliminate dissolved gases from a liquid product, a deaeration module which is divided by a gas-pervious membrane into a liquid phase side and a vapor phase side is used. A deaeration-use gas composed of one or more kinds of inactive gases is previously dissolved in a liquid product to be deaerated, whereby a deaeration-target liquid is prepared. The deaeration-target liquid is distributed on the liquid phase side, in which distribution process the deaeration-use gas moves to the vapor phase side via the gas-pervious membrane, while the dissolved gases move to the vapor phase side along with the movement of the deaeration-use gas. This movement of the gases is carried out during passage through the deaeration module under ambient pressure.

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 process for supplying a flow of nitrogen to a site having flowrate requirements varying between a nominal flowrate and a range situated thereabove comprising: a) passing compressed air into a main line in a separating assembly formed by at least two membrane separation lines mounted in parallel, wherein at least one of the separation lines can be shut off from the main line, the separating assembly having one of the following configurations: a1) when the flowrate requirements are situated at a level of the nominal flowrate, all of the membrane separators of the assembly are in operation, none of the separating lines being shut off; a2) when the flowrate requirements of the site exceed a predetermined flowrate, at least one of the lines of the separating assembly is shut off, keeping at least one separation line and its membrane separator in operation; b) advancing nitrogen gas obtained at the outlet side of each of the membrane separators to a collector connected downstream of the main line; c) evacuating g

Abstract: The invention relates to a process for the separation of a gaseous hydride or a mixture of gaseous hydrides from a gaseous medium containing at least one gas from the group consisting of H.sub.2, Ar, He, according to which the gaseous medium is passed on to a membrane module so that the concentration of the hydride or of the mixture of hydrides obtained at the outlet of the module is higher than their initial concentration in the gaseous medium.

Abstract: The present invention relates to a process and an apparatus for providing an enriched oxygen gas stream. A countercurrent sweep gas stream is provided to the permeate side of the hollow fiber membranes internally of a gas separation module.

Abstract: Novel aromatic polyetherketone gas separation membranes and the process of using such membranes to separate one or more gases from a gaseous mixture are disclosed. The polyetherketones are formed from 2,6-dihalobenzophenone, preferably 2,6-difluorobenzophenone.

Abstract: A process for supplying nitrogen to at least two user stations, whose requirements as to nitrogen purity are different. Compressed air is passed from an air compressor (12) to at least one air treatment station (13) permitting effecting at least one of the following treatments of oil removal, filtering out a major portion of the particles, drying, and bringing the air to the desired temperature. The compressed air is then sent to a centralized gas separation unit (14), so as to produce at the outlet of the unit impure nitrogen of intermediate purity. The gas from the centralized separation unit (14) is directed to at least two utilization lines (3-5), each comprising a local gas separation unit (6-8), in which the gas is again treated, so as to obtain at the outlet of each local separation unit nitrogen of a purity suitable for the uses of each of the user stations (9, 10) at the end of the line.

Abstract: Air is separated in a vessel housing gas separation membranes. A flow control valve controls the passage of air to an inlet header of the vessel. The setting of the valve is adjusted in accordance with the level of oxygen impurity in product nitrogen leaving the vessel for an outlet header. A second flow control valve is provided and is of a kind whereby product nitrogen is able to be delivered at a constant flow rate over a range of different pressures upstream thereof. Accordingly, the apparatus is able to deliver nitrogen at a desired purity and flow rate.

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: The present invention is a pressure swing adsorption process for separating a more strongly adsorbed gas component from a less strongly adsorbed gas component in a feed gas mixture at higher recoveries and productivity and less capital cost by the use of void space gas recycle, membrane based nitrogen enrichment of feed gas and the elimination of pressure equalization steps. The process is particularly amenable to air separation wherein nitrogen product is recovered and an oxygen byproduct is removed.

Abstract: A separation of gas by permeation, comprising the steps of and the apparatus for compressing a gaseous mixture to be separated at a first temperature (Ta) in a compressor (2), cooling to a second temperature (To) the compressed mixture to condense condensable impurities in the compressed gaseous mixture, purifying the compressed gaseous mixture of condensable and/or adsorbable impurities at a third temperature (T.sub.1) greater than the second temperature (T.sub.0) and passing the purified gaseous mixture into a gaseous permeation unit comprising at least one membrane module to obtain at least one production gas. The third temperature (T.sub.1) is so regulated that it will not be less than a first predetermined value. The second temperature (To) is greater than the first temperature (Ta) by a value comprised between 1.degree. and 5.degree. C., the first value being not less than 20.degree. C.

Abstract: Advanced membrane compositions having high permeability characteristics, and optimal operating temperatures above ambient during only a portion of the year, are operated with a controlled reduction in operating feed air pressure under rising ambient temperature conditions. The overall efficiency of the air separation process is enhanced, and power requirements are significantly reduced.

Abstract: A process for removing inorganic components from water is disclosed. The process involves gas stripping followed by membrane separation treatment of the stripping gas. The stripping step can be carried out using one or multiple gas strippers and using air or any other gas as stripping gas. The membrane separation step can be carried out using a single-stage membrane unit or a multistage unit. Apparatus for carrying out the process is also disclosed. The process is particularly suited for treatment of contaminated groundwater or industrial wastewater.

Abstract: Oxygen-separating porous membranes comprise a complex of (a) a transition metal (II) ion, (b) a ligand, and (c) an aromatic amine, retained in the pores of a substrate.

Abstract: A solid body having extremely narrow passages formed therein for the separation and conveyance of gases by surface diffusion. Because of the relatively high flow resistance resulting from the extremely small cross sections of the passages, the gas conveyance through the solid body can be performed substantially exclusively by surface diffusion. Only those gas particles which are adsorbed on the solid body or on the wall of the passages will be conveyed through the solid body. The surface diffusion can be controlled by suitable selection of the gas/solid body combination. The diffusion is influenced particularly by the temperature of the solid body. When, in the case of a two-gas mixture, the solid body is heated to a temperature above the desorption temperature of one of the gases and below the desorption temperature of the other gas, only the gas particles of the adsorbed gas are conveyed on the passage walls by surface diffusion.

Abstract: Novel alkyl-substituted aromatic polyethersulfone gas separation membranes and the process of using such membranes to separate one or more gases from a gaseous mixture is disclosed. The polyethersulfones are formed from aromatic alcohols of the formula ##STR1## where Z is independently alkyl groups having 1 to 10 carbon atoms, most preferably a tertiary butyl group, n is an integer from 1 to 4, preferably 1.

Abstract: Novel substituted aromatic polyetherketone gas separation membranes and the process of using such membranes to separate one or more gases from a gaseous mixture is disclosed. The polyetherketones are formed from aromatic alcohols of the formula ##STR1## where Z is independently alkyl groups having 1 to 10 carbon atoms, most preferably a tertiary butyl group, n is an integer from 1 to 4, preferably 1.

Abstract: A nitrogen gas source for providing nitrogen gas at sequential work sites includes a channel for containing flowing gas at a pressure greater than ambient atmospheric pressure. A compressor provides compressed air at a pressure greater than atmospheric pressure to an up-stream end of the channel. A central portion of the channel includes a nitrogen module with a membrane wall portion for selectively constraining nitrogen within the channel while allowing other gases to escape from the channel through the membrane. A downstream portion of the channel includes a bifurcated channel section with a first bifurcated section passage having a first flow restrictor and second bifurcated section passage having a second flow restrictor. A two position valve allows flowing gas to be selectively directed through the first or second passage.

Abstract: Apparatus for producing a hypoxic gas mixture having a higher nitrogen-to-oxygen ratio than atmospheric air has a diaphragm compressor feeding air under pressure to an oxygen-depleting unit having a perforate tube extending axially of a cylindrical chamber having an outlet in one side. The annular space between the perforate tube and the wall of the chamber is filled with axially extending hollow fibers of poly-4-methyl-penthene-1. Ends of the chamber are closed except for the interiors of the hollow fibers which are open to the atmosphere. The walls of the hollow fibers are more permeable to oxygen than to nitrogen so that part of the oxygen escapes through open ends of the hollow fibers, thereby increasing the nitrogen-to-oxygen content of the gas.

Abstract: Multi-stage membrane systems are arranged so that, with the same number of modules and compressors, mixing losses upon combining recycle and feed streams are minimized. Membrane surface area and power requirements are reduced thereby.

Abstract: The present invention relates to fluid separation composite membranes prepared from sulfonated aromatic polymers in lithium salt form with sulfonic acid groups attached to aromatic rings that are incorporated into the main polymeric backbone.

Abstract: Dopable, fully dense polymer membranes are used to form membranes having selective permeabilities. To improve selectivity, the membranes may be subjected to chemical or electrochemical treatment with electron donors or acceptors to alter the doping level of the polymer membrane, generally in a reversible fashion. This leads to significant changes in gas permeation rates relative to what is observed for the non-doped, fully dense polymers. This change in doping level of the polymer films can be precisely controlled by varying the concentration and nature of chemical dopants used. Desirable changes in permeation rates are achieved by a treatment which comprises a reversal doping of the polymeric material, followed by removal of the dopants (to provide an "undoped" polymer).

Abstract: A hollow fiber blood oxygenator is provided having an plurality of enclosed, coaxial heat exchanger coils, having a common header to insure uniform temperature in the coils. An enclosed fiber bundle is concentrically positioned inside the heat exchanger coils to define a flow path around the coils and through the fiber bundle. The heat exchanger coils and the outside of the fiber bundle are tapered to provide a close fit. Gas manifolds direct gas flow to and from the hollow fibers.