Abstract: A high pressure purge is incorporated into the cycle of a PSA process designed for the recovery of strongly adsorbed product gas from a gas mixture. The high pressure purge stream is obtained by compressing the low pressure cocurrent purge step that precedes the countercurrent depressurization or evacuation step. The high pressure purge step is included in the cycle following the adsorption step of the process.

Abstract: A feedstream comprising nitrous oxide is purified by a pressure swing adsorption process employing a copurge with an oxygen-lean stream to produce a high purity nitrous oxide stream. The high purity nitrous oxide stream can be incorporated in a complex for the production of adipic acid to recover nitrous oxide from a dilute waste stream and pass the recovered nitrous oxide to a process for the production of phenol from an aromatic hydrocarbon. Unreacted nitrous oxide from the phenol production step acid can be recovered in a second, or vent PSA step, and combined with the recovery of byproduct nitrous oxide waste streams from the production of adipic for the overall recovery of nitrous oxide, thereby significantly reducing nitrous oxide emissions from the production of adipic acid.

Abstract: A molecular sieve type gas separation apparatus (10) for separating product gas from a gas supply (14) includes at least one sieve bed (11-13) which during an adsorption charge phase of a cycle, adsorbs non product gas in the gas supply (14), and in a desorption regeneration phase of the cycle desorbs the previously adsorbed non product gas. The apparatus further includes an outlet (18) to which product gas is delivered during the adsorption charge phase, and an outlet (31) for non product gas during the desorption regeneration phase. A sensor (36) responsive to the concentration of a constituent in the product gas, and a control (20) to switch the apparatus (10) between the adsorption charge and desorption regeneration phases are further provided. The control (20) is adapted to adjust the duration of adsorption charge phase relative to the duration of the desorption regeneration phase in each cycle.

Abstract: The device comprises an adsorber (1) and three outlet capacities (2-4), first (8, 9) and second (10, 11) structure to establish bidirectional communication between the adsorber and the elution capacity (2) and the repressurization capacity (3), respectively, and third structure (14A, 15; 16) to establish unidirectional communication from the adsorber to the production capacity (4).

Abstract: A rapid pressure swing adsorption oxygen concentrator is provided having a plurality of at least three sieve beds cycled in sequence such that each is pressurized during one segment of a cycle and depressurized during a plurality of segments of a cycle while the other sieve beds are being sequentially pressurized. Preferably, approximately six sieves are provided and pressurized in sequence, with each being pressurized for approximately 60.degree. of the cycle and depressurized for from about 270.degree. to 300.degree. of the cycle. Each sieve is thereby pressurized for about one to two seconds and depressurized for about five to ten seconds. By utilizing the ability of the sieve material to adsorb faster than it can desorb gas, high output of up to 96% pure oxygen results with a low sieve volume and low power consumption.

Abstract: Pressure swing adsorption (PSA) separation of a gas mixture is performed in an apparatus with a plurality of adsorbent beds. The invention provides rotary multiport distributor valves to control the timing sequence of the PSA cycle steps between the beds, with flow controls cooperating with the rotary distributor valves to control the volume rates of gas flows to and from the adsorbent beds in blowdown, purge, equalization and repressurization steps.

Abstract: Pressure swing adsorption (PSA) separation of a feed gas mixture is performed within an apparatus having typically a single prime mover powering a feed compressor for one or multiple rotary PSA modules in parallel, each module including a rotor with a large number of angularly spaced adsorber elements, with valve surfaces between the rotor and a stator so that individual adsorber elements are opened to compartments for staged pressurization and blowdown, with thermally boosted energy recovery from staged expansion of countercurrent blowdown and light reflux gases, and a plurality of adsorber elements opened at any instant to each compartment so that each compressor and expander stage operates under substantially steady conditions of flow and pressure.

Abstract: The present invention relates to the recovery of low purity oxygen gas from the top of an adsorber vessel into a receiver tank to be used as a purge reflux gas. Recovery of void gas results in improved process efficiency. The invention may also employ a simultaneous evacuation from the top of the adsorber to remove the lower purity void gas while the main waste evacuation step is conducted. This simultaneous co-current top void gas recovery and counter-current waste evacuation from both ends of the adsorber allows for an overall increase in product recovery of between 3-5% over conventional processes.

Abstract: High purity strongly adsorbed gas, e. g., carbon monoxide, is separated from a gas mixture containing one or more other gas components, e. g., hydrogen carbon dioxide, methane, nitrogen and possibly other impurities, by a two-phase pressure swing adsorption process carried out in one or more adsorption vessels arranged in parallel and containing adsorbent which adsorbs the strongly adsorbed gas more readily than the other components of the gas mixture. The process includes two evacuation steps and two or more purge steps.

Abstract: The present invention is a process for adsorbing carbon dioxide from a carbon dioxide containing gas mixture comprising contacting the gas mixture with an activated carbon adsorbent having a density in the range of approximately 0.56 to 0.61 g/cc (35 to 38 lbs./ft.sup.3) and adsorbing the carbon dioxide on the activated carbon adsorbent.

Abstract: Carbon dioxide is separated from gaseous hydrocarbons by a cyclic adsorption process using at a temperature in the range of about -50 to about 200.degree. C., wherein the adsorption step of the process is conducted by passing the gas mixture through an adsorption zone containing carbon molecular sieve or type A zeolite whose exchangeable cations are made up of about 50 to about 90% sodium ions and about 10 to about 50 percent potassium ions.

Abstract: A high purity isobutane adsorption separation and purification apparatus is provided including a pressure regulator which regulates the pressure of an isobutane-containing gas; the at least one adsorption bed packed with zeolite 5A and carbon molecular sieve arranged downstream of and operatively associated with the pressure regulator; a flow control valve disposed between the pressure regulator and the at least one adsorption bed; a surge tank operatively associated with and for receiving a purified isobutane product from the at least one adsorption bed; a vacuum pump operatively associated with and for removal of impurities from the at least one adsorption bed; and valves disposed between the pressure regulator and the at least one adsorption bed, between the at least one adsorption bed and the surge tank, and between the at least one adsorption bed and the vacuum pump. An adsorptive separation and isobutane purification process is also provided which may be used with the apparatus of the invention.

Abstract: In a process for separating a gas mixture in a pressure swing adsorption device comprising an adsorber, two outlet vessels and a rotary machine at the inlet, the rotation of the rotary machine is reversed during the first depressurization step (c-d) then during the first repressurization step (g-h), so that these first steps are each broken down into two sub-steps in which the inlet for the adsorber successively experiences two opposite flows, whereas the outlet of the adsorber experiences a flow, respectively leaving or entering, of constant direction. The process is particularly useful in the production of oxygen from air.

Abstract: A vacuum pressure swing adsorbent (VPSA) system and method for separating a component from a fluid mixture and including a fluid source for introducing the mixture into the system and a supply apparatus for collecting the separated component. A pair of adsorbent bed vessels is interposed between the fluid source and the supply apparatus to adsorb and desorb a predetermined component under respective adsorption and desorption pressures characterized by a low pressure ratio and relatively high desorption pressure values. Implementation of a single-stage vacuum device made possible by the use of the high desorption pressure, results in further reduction in both equipment and operating costs.

Abstract: A PSA process involving the storage of products of various purities in segregated storage tanks for subsequent usage is disclosed. Products of increasing purities, admitted at the product end of the bed, are used during purging and repressurization steps. In addition, different composition streams collected at the feed end of the bed during the countercurrent depressurization step are admitted at the feed end of the bed, in the order of increasing product component content, during the rising pressure step(s). This cycle gives higher recovery and lower bed size factor than prior art PSA cycles.

Abstract: In an adsorptive alternating pressure process for the enrichment of air with oxygen using a molecular sieve zeolite in an adsorber, wherein adsorbed components are desorbed under a pressure below the pressure at which air separation and N.sub.2 adsorption is effected and, after desorption, the molecular sieve adsorber is at least partly returned to the air separation pressure with oxygen gas produced in countercurrent to the air separation gas flow, the improvement which comprises cooling product gas and covering the molecular sieve adsorber with the cooled product gas.

Abstract: A process for separating the components of a gas mixture in a single adsorption vessel pressure swing adsorption system including the steps: (a) cocurrently passing the gas mixture through the adsorption vessel at a desired adsorption pressure and collecting the nonadsorbed product gas in a storage vessel, (b) cocurrently depressurizing the adsorption vessel and pumping gas removed from the adsorption vessel during this step to the storage vessel, (c) regenerating the adsorbent in the adsorption vessel by countercurrently depressurizing the adsorption vessel, and (d) repressurizing the adsorption vessel to the desired adsorption pressure. Steps (a) and (b) are carried out using gas pumping or compressing devices, and the same or different gas pumping or compressing devices can be used for steps (a) and (b). Step (c) can also be carried out with the pumping device used in step (a).

Abstract: A process and apparatus for separating the components of a gas mixture by PSA in a four-vessel adsorption system operated as two pairs of adsorption vessels. The vessels of each pair are operated 180.degree. out of phase, such that one vessel of a pair is in the adsorption mode while the other vessel of the pair is undergoing adsorbent regeneration. The apparatus includes the two pairs of adsorption vessels, an intermediate gas storage reservoir which is used to temporarily store gas removed from the nonadsorbed gas outlet end of the adsorption vessels for use in various steps of the process, one gas blower and a pair of vacuum pumps. The adsorption cycle is such that the pairs of adsorption vessels are operated out of phase relative to each other and the blower and both vacuum pumps are in continuous operation throughout the process. The process and system are particularly well adapted to the separation of nitrogen from oxygen by vacuum swing adsorption.

Abstract: High purity carbon monoxide is separated from a gas stream containing carbon monoxide, carbon dioxide, methane, hydrogen and possibly other impurities by a two-stage pressure swing adsorption process carried out in a series of adsorption vessels containing adsorbent which adsorbs carbon monoxide more readily than other components of the gas stream. The first adsorption vessel in the series is cocurrently purged with nonadsorbed product stream from the second vessel and the purge effluent from the first stage adsorption vessels is reintroduced into the first adsorption vessels as feed gas.

Abstract: In order to provide a pressure-swing-adsorption oxygen production process which can maintain the product recovery at a high level while enhancing the oxygen productivity and reducing the unit power consumption, a pressure recovery step is carried out in which communication is provided between an outlet end of an adsorption column which has completed an adsorption step and an outlet end of an adsorption column which has completed a regeneration step, and in which gas remaining in the adsorption column which has completed the adsorption step is collected within the adsorption column which has completed the regeneration step; and simultaneously with the pressure recovery step, a gas mixture which has approximately the same composition as feed gas mixture is introduced into at least one of the adsorption column which has completed the adsorption step and the adsorption column which has completed the regeneration step through the inlet end thereof.

Abstract: Substantially all of the carbon dioxide is removed from a gas containing up to about 1% by volume carbon dioxide by subjecting the gas to a pressure swing adsorption process using as the adsorbent a single layer of zeolite having a silicon to aluminum atomic ratio in the range of 1.5 to 70. The process is particularly suitable for removing substantially all carbon dioxide and water vapor contained in air prior to subjecting the air to cryogenic distillation.

Abstract: This process comprises at least one stage of first decompression/first recompression by balancing the pressures between two adsorbers (2A to 2D) as well as the taking off of a constant product gas rate during the adsorption phase. In the course of the first decompression, the product gas taken off is passed to an auxiliary capacity (6) which is arranged in parallel to the product line (1) and can be connected to the product outlet side of each adsorber (2A to 2D). During the second recompression stage, the adsorber receives the product gas taken off in countercurrent and is at the same time put into communication with the auxiliary capacity. The process is useful in the production of hydrogen from a constant rate of a feed gas mixture.

Abstract: The apparatus for the separation of a gas mixture by pressure swing adsorption (PSA) comprises at least one adsorber A and a first vessel T which can be selectively connected to the adsorber in order temporarily to store the gas which is extracted from the adsorber and reintroduced into it during a cycle, the vessel T having a fixed free internal volume V, a vertical main direction of height h, with the relationship 25.ltoreq.h.sup.3 /V.ltoreq.150, and the gas fraction entering and leaving the vessel T at its lower part, and remaining therein for a time which does not exceed 300 seconds. The apparatus is useful in the production of oxygen or hydrogen.

Abstract: A method is provided for separating one or more volatile contaminant components from a gas using a pressure and temperature swing adsorbent filtration filter bed system containing three or more layers of adsorbent materials characterized in that the layers comprise a first layer of adsorbent material, a second layer of dessicant material and a third layer of material capable of adsorbing contaminants that are not retained by the first layer. Preferably the third layer is capable of adsorbing contaminants of relatively low boiling point, e.g. of boiling point less than 50.degree. C., and preferably comprises a microporous adsorbent. The second layer of dessicant material preferably comprises a zeolite.

Abstract: A process for the treatment of a gaseous mixture by adsorption with variable pressure, in an adsorption installation comprising at least one adsorber. For each adsorber, there is a succession of steps defining an adsorption phase, a regeneration phase for the adsorbent comprising a depressurization step, and a pressure increase phase. The passage from one phase to the following comprises switching of at least one valve between open and closed positions. At least one valve switching is carried out according to a programmed progressive slope to control a first cocurrent decompression stage of the adsorber with transfer of gas toward a lower pressure portion of the installation. The transferred gas is sent, for at least partially balancing pressure, to another adsorber in a pressure increase phase.

Abstract: An improved oxygen generator (20) includes an air compressor (21) having a pressure port (22) and a suction port (23) and being selectively operable to produce a flow of air from the suction port to the pressure port; a molecular sieve (30) having an inlet communicating with the compressor and having an outlet, the sieve being adapted to adsorb nitrogen from a flow of gas passing therethrough; a storage tank (33) communicating with the sieve outlet and adapted to store oxygen-rich gas passing through the sieve; and a control valve (24) operatively arranged between the compressor and the sieve and being selectively movable between a first position in which air flows from the compressor suction port through the sieve to the storage tank and a second position in which oxygen-rich gas flows from the storage tank through the sieve and control valve to desorb nitrogen in the sieve.

Abstract: A process for removing nitrogen oxides, as well as water and carbon dioxide, from gas streams containing at least 0.2 ppm by volume of nitrogen oxides by passing the gas stream through an alumina adsorbent and a zeolite adsorbent, preferably 13X-zeolite. The process has utility in front end cleanup of air prior to cryogenic distillation of the air where nitrogen oxides would otherwise freeze under the cryogenic processing.

Abstract: A pressure swing adsorption process for absorbing CO.sub.2 from a gaseous mixture containing CO.sub.2 comprising introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100.degree. C. and 500.degree. C. to adsorb CO.sub.2 to provide a CO.sub.2 laden alumina adsorbent and a CO.sub.2 depleted gaseous mixture and contacting the CO.sub.2 laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO.sub.2 from the CO.sub.2 laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100.degree. C. and 600.degree. C., is not degraded by high concentrations of water under process operating conditions.

Abstract: A process for separating oxygen and nitrogen using an adsorption system comprising at least one main adsorption vessel containing an adsorbent selective for one component and at least one auxiliary adsorption vessel containing an adsorbent selective for the same component, the auxiliary vessel(s) being operated under conditions which result in the production of a product gas of lower purity than the product gas from the main adsorption vessel(s). The lower purity product gas from the auxiliary vessel is used to purge or pressurize the main adsorption vessel(s).

Abstract: An air prepurification process carried out in a battery of three adsorption vessels arranged in parallel. The process includes three steps: a first step in which non-steady state PSA is carried out in the first and second vessels operated in alternating adsorption and bed regeneration mode while the adsorbent in the third vessel undergoes thermal regeneration; a second step in which non-steady state PSA is carried out in the second and third vessels operated in alternating adsorption and bed regeneration modes while the adsorbent in the first vessel undergoes thermal regeneration; and a third step in which non-steady state PSA is carried out in the first and third vessels operated in alternating adsorption and bed regeneration modes while the adsorbent in the second vessel undergoes thermal regeneration.

Abstract: A process and apparatus for drying and removing carbon dioxide from a hydrogen and carbon monoxide containing synthesis gas by using adsorption vessels containing a first layer of 13 X-zeolite and a second layer of 3 A-zeolite in which the 3 A-zeolite precludes the formation of water of reaction when dry and carbon dioxide-free synthesis gas is used to regenerate the adsorption vessel countercurrent to feed flow of the synthesis gas.

Abstract: A single-bed PSA system comprising a blower, an adsorber vessel, and a gas product storage tank separates a gas mixture using a three-step cycle comprising adsorption, evacuation, and pressurization. Pressurization is accomplished by introducing gas from the gas product storage tank into both the feed end and the product end of the adsorber vessel. Preferably a portion of the pressurization gas is introduced into the adsorber vessel by the blower, which also is used for providing feed to the adsorber and for withdrawing gas from the adsorber during the evacuation step.

Abstract: This process carries out a cycle on a monoadsorber (1) connected, on the one hand, to at least one container (2, 3) via a line (8, 10) fitted with a variable-opening valve (9, 11) and, on the other hand, to a reversible compression/pumping machine coupled to a speed variator (5). Application in particular to the production of oxygen at a variable flow rate from atmospheric air.

Abstract: A pressure swing adsorption apparatus to vary selectively the concentration of at least one constituent of a gaseous mixture by sending a gaseous mixture into an adsorber to generate a particular product gas while delivering to another adsorber both a predetermined portion of the product gas to purge the other adsorber of its adsorbed gas and a selected amount of the product gas, independent of the flow rate and in addition to the predetermined portion, to produce a desired relative concentration of the constituents of the product gas from a range of relative concentrations.

Abstract: This invention relates to a VPSA method for the production of a product that is enriched with a more preferred gas from a mixture of the more preferred gas and a less preferred gas and, preferably to a VPSA method for the production of an oxygen-enriched product from air, using an oxygen-preferential adsorbent under equilibrium conditions. In a preferred embodiment the process uses a desorption purge at a nearly constant pressure that is selected to produce a steady stream of oxygen having a purity from 30% to 60% at a pressure in the range of 60 kPa to 20 kPa.

Abstract: A gas flow distribution system accumulates a sample from a sample bearing carrier gas in a micro-accumulator, delivers it using a carrier gas to a gas chromatography column, and supplies a carrier gas to the gas chromatography column to facilitate separation of the sample into sample components and transport the sample components to a mass spectrometer for trace vapor detection and analysis or testing in real time. The system is made of inert components and configured to have low dead volume for improved performance and accuracy of detection. External valves are employed for easy management and balance of the flow in the system to minimize operation time and facilitate continuous accumulation, delivery, and testing of the sample. The delivery of the sample to the gas chromatography column using an electrically heated cold trap as the micro-accumulator can be performed extremely fast.

Abstract: Four adsorbers 1 to 4, each operating in a cycle comprising (described for adsorber 2): an adsorption step 1 wherein a feed from adsorber 2 is circulated to adsorber 2; an adsorption step 2 wherein feed is injected to the bottom of adsorber 2 and a product rich in isoparaffins is recovered from the head of adsorber 2; an adsorption step 3 wherein a portion of the fluid leaving adsorber 2 is sent to adsorber 3; an adsorption step 4 wherein the head of adsorber 2 receiving the feed is connected to the bottom of adsorber 3; a first depressurisation step 5 wherein adsorber 2 at high pressure is connected to adsorber 4 at a lower pressure; a second depressurisation step 6 wherein the head of adsorber 2 is closed; a stripping step 7 wherein the bottom of adsorber 2, which receives desorbent overhead, is connected to the top of adsorber 2; two principal stripping steps 8 and 9 wherein adsorber 2 alone is supplied with desorbent; a stripping finishing step 10 wherein adsorber 2 is continued to be supplied with desorb

Abstract: A method of controlling an oxygen concentrator having a first sieve bed operated over successive control periods according to a duty cycle for alternately pressurizing and flushing the first sieve bed and a second sieve bed operated over the successive control periods according to a reciprocal of the duty cycle is disclosed. The duty cycle and the reciprocal duty cycle are adjusted during every second one of the successive control periods to change the pressurizing relative to the flushing of the first sieve bed and to change the flushing relative to the pressurizing of the second sieve bed, for reducing concentration of oxygen produced. The duty cycle and the reciprocal duty cycle are adjusted during remaining control periods to change the flushing relative to the pressurizing of the first sieve bed and to change the pressurizing relative to the flushing of the second sieve bed, such that water vapor is purged from the first and second sieve beds after pressurizing thereof.

Abstract: Temperature swing adsorption to remove CO.sub.2 from a gas stream is conducted using alumina to adsorb all the water and at least most of the carbon dioxide from the gas stream. Optionally a downstream zone of zeolite may be provided to remove further carbon dioxide and hydrocarbons.

Abstract: A process and apparatus for separating the components of a gas mixture in a pair of adsorption vessels using a single gas compressor/pump to move gas into and out of the adsorption vessels. The cycle is such that the gas compressor/pump is in continuous operation. The adsorption cycle is non-symmetrical in that the series of steps carried out in one of the adsorbers is not the same as the series of steps carried out in the other adsorber. The apparatus includes an intermediate gas storage container which is used to temporarily store gas removed from the nonadsorbed gas outlet end of the adsorption vessels so that it can be used to partially pressurize the adsorption vessels upon completion of the adsorbent regeneration step of the adsorption cycle.

Abstract: Ozone is recovered from an ozone-oxygen mixture by adsorption using an adsorbent which comprises a zeolite selected from the group consisting of L type zeolite, Y type zeolite, ZSM-5, and mordenite in which at least 90% of the exchangeable cation content is in the ammonium form and the molar ratio of potassium to aluminum is less than about 0.25. Alternatively, a proton-exchanged L type zeolite can be used in which at least 90% of the exchangeable cation content is in the proton form and the molar ratio of potassium to aluminum is less than about 0.25.

Abstract: A process is set forth for the selective removal of water, CO.sub.2, ethane and C.sub.3 + hydrocarbons from gas streams, particularly a natural gas stream comprising primarily methane. The process comprises contacting the gas stream with an adsorbent material consisting exclusively of one or more compounds which are basic (i.e. compounds which, when contacted with a pH neutral aqueous solution, cause such solution to have a pH greater than 7.0) and which are mesoporous (i.e. compounds which have moderately small pores providing a surface area less than 500 m.sup.2 /g). The key to the present invention is the use of a single homogenous adsorbent without sacrificing performance. Typical mesoporous adsorbents which are useful in the present invention include zinc oxide, magnesium oxide and, in particular, activated alumina.

Abstract: Krypton present in a trace amount in a gaseous oxygen/nitrogen mixture is effectively enriched by an adsorption/desorption process of the pressure variation mode using a system including at least three fixed bed adsorption columns packed with hydrogenated mordenite. At the end of adsorption operation in one column, a desorbed gas from another column is fed to the one column under substantially the same pressure as the pressure during adsorption operation for fully washing the one column. Thereafter, the one column is subject to desorption operation.

Abstract: A process for the treatment of natural gas that contains an odorant at a storage site is described, with this process including a storage phase and a draw-down phase which involve at least two adsorbers A and B and in which, during the storage phase, the odorant is extracted from the gas and, during the draw-down phase; the water and H.sub.2 S that are contained in the gas are extracted.

Abstract: A natural gas feed stream containing significant quantities of nitrogen and/or carbon dioxide can be increased to a content of greater than 95 percent by volume of natural gas, and preferably greater than about 98 percent, by passing the natural gas feed stream sequentially through three adsorbent beds that are cycled through seven phases comprising: an adsorption phase to adsorb a first gas, a first depressurization phase to remove feed gas from the voids in the adsorbent bed, a recycle phase to remove a second gas from the adsorbent by the passage of a second depressurization gas therethrough and to produce a recycle gas, a second depressurization phase to reduce the adsorbent bed pressure to about ambient and to produce the second depressurization gas, an evacuation phase where the pressure in the adsorbent is further reduced and an enriched primary gas product stream recovered, a pressurization phase where the pressure in the adsorbent bed is increased using secondary product gas from a bed in an adsorpti

Abstract: A device for separation of gas by adsorption, of the so-called VSA or MPSA type, comprises, between a utilization line (L) and a source (S) of gaseous mixture to be separated, at least one module (M) comprising in series a reversible rotary machine (R), typically a Roots machine, an adsorber (A) and a shut-off valve (V), the rotary machine (R) being alternately actuated, in one direction during a first phase of pressurization and of production and then, in the other direction, during a second phase of depressurization and desorption. Used particularly in the production of small and medium volumes of oxygen in modular installations.

Abstract: A condensable component present at low concentration in a feed gas mixture containing the condensable component and a noncondensable component is recovered by selective adsorption from the feed gas mixture in an adsorption step, the resulting adsorbed condensable component is desorbed by a heated purge gas in a regeneration step to yield a purge gas effluent enriched in desorbed condensable component, and the purge gas effluent is cooled to condense and recover the condensable component as a liquid.

Abstract: Process for treating a gas mixture by pressure swing adsorption wherein for each adsorber (1), the duration (T.sub.R) of the countercurrent recompression step is much less than that (T.sub.D) of the cocurrent decompression step. The process is particularly useful in the production of oxygen from atmospheric air.

Abstract: In a process of recovering oxygen-enriched gas by pressure swing adsorption with use of adsorbers (A, B) each packed with an adsorbent which selectively adsorbs nitrogen from a gas mixture mainly containing nitrogen and oxygen, recovery of remaining oxygen-enrich gas is fully carried out by pressure equalization between both adsorbers (A, B), and a vacuum pump (8) is always connected to either adsorber (A or B) for continuous evacuation of nitrogen. For this purpose, the pressure equalization between both adsorbers (A, B) is conducted at least in two steps wherein one adsorber (A or B) is pressurized, whereas the other adsorber (B or A) is pressurized, so that recovery of oxygen-enriched gas is possible until there is substantially no pressure difference between both adsorbers (A, B).

Abstract: The invention relates to an apparatus and method for controlling the pressure in a fuel tank ullage. The apparatus includes a vapor pump which withdraws vapors from the tank ullage responsive to a signal generated by a pressure sensor in communication with the ullage. The vapors are directed to a canister containing a VOC-adsorbent material where the VOC content of the vapor is removed. Non-polluting VOC-free air is vented from the canister to the atmosphere. The invention also contemplates the provision of a second canister which would accept the tank ullage vapors after the material in a first canister becomes saturated. A portion of the VOC-free air exiting the first canister is used a purge gas to regenerate the saturated material in the first canister. The operation of the multiple canisters would alternate between adsorption and regeneration until the tank ullage pressure is reduced to below a threshold level.