Abstract: A PSA process for the separation of a feed gas, for example air, containing at least one first component, such as nitrogen, and a second component, such as oxygen, by preferential adsorption of the first component at a high adsorption pressure, on at least one bed of particles of an adsorbent material and recovery of a gas flow enriched in the second component, with desorption of the first component at a low desorption pressure. The ratio (.mu./.sigma.) of the mean granulometry (.mu.) of the adsorbent particles contained in the bed, to the breadth of granulometric distribution (.sigma.) of the particles, is comprised within the range 1.5 to 15, the particles of adsorbent material being particles of zeolite, such as zeolite X or zeolite LSX, exchanged by metallic cations, preferably cations of lithium and/or calcium.

Abstract: A process and apparatus for separating a gas from a gas mixture. The apparatus includes a vessel having an interior with a bed of adsorbent disposed therein. First and second passages communicate with the interior of the vessel. In a first step, the gas mixture is fed to the bed via the first passage and discharged from the bed via the second passage. In a second step, rest gas is evacuated from the bed via the first passage. In a third step, the gas mixture is fed to the bed via the second passage and discharged from the bed via the first passage. In a fourth step, rest gas is evacuated from the bed via the second passage.

Abstract: Novel gas separation agents with precisely and predictably controlled pore sizes within the range of 3-4 Angstrom units and their preparation from ETS-4 by exchange with cations, particularly multivalent cations such as strontium followed by drying and calcination to effect controlled pore shrinkage is disclosed. These novel materials have utility in gas separation processes particularly the separation of nitrogen from a mixture of the same with methane.

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 separation of a feed gas mixture, to obtain a purified product gas of the less strongly adsorbed fraction of the feed gas mixture, is performed with a cooperating set of "N" adsorbers in a rotary assembly, with each adsorber communicating at its product end directly to a rotary cyclic displacement chamber, and at its feed end by rotary distributor valve ports to a rotary piston feed compressor and a rotary piston exhaust vacuum pump. The compressor and vacuum pump are integrated with the cycle, and rotate at "N" times the cycle frequency. Alternative adsorber configurations for high frequency operation are disclosed.

Abstract: A heterogeneous adsorbent for the separation of gases, comprising particles of at least one zeolite containing at least one exchanged metal cation selected from monovalent, divalent and/or trivalent cations, the zeolite having an exchange-factor distribution of given mean having a standard deviation for the exchange-factor distribution of between about 0.3% and 5%, and a PSA, VSA or TSA process for separation of a gas flow, such as air, containing at least a first compound, such as nitrogen, which is adsorbed preferentially on the heterogeneous adsorbent, and at least a second compound, such as oxygen, which is less preferentially adsorbed on the heterogeneous adsorbent than the first compound.

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: A separation process, involving an adsorber containing at least one adsorbent with an inlet and outflow, involves the following stages of the cycle:--stage I, repressurization from the low pressure of the cycle;--stages II and III during one of which the high pressure of the cycle is reached; and stage IV, depressurization/purging, during which the low pressure of the cycle is reached. Each stage (I to IV) involves a fixed gas flow (F) at one end of the adsorber and a free gas flow (.lambda.) at the other end of the adsorber, the fixed flows (F) addressing the inlet (E) and outlet (F) ends of the adsorber from one stage (I to IV) to the next. The process is particularly applicable to the production of oxygen from air.

Abstract: The present invention relates to binder-free molecular sieve zeolite granules of lithium zeolite A and lithium zeolite X, a process for preparing these molecular sieve zeolite granules and their use for preparing nitrogen or oxygen from air by pressure swing adsorption.

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: A novel heat-resistant low-silica zeolite, an industrial production process, and uses of the low-silica zeolite are provided. The heat-resistant low-silica zeolite contains Si and Al in a molar ratio of SiO.sub.2 /Al.sub.2 O.sub.3 ranging from 1.9 to 2.1, and has sodium and/or potassium as metal cation, wherein the low-silica zeolite contains low-silica faujasite type zeolite at a content of not lower than 88%, and has a thermal decomposition temperature ranging from 870.degree. C. to 900.degree. C. in the air. The process for producing the heat-resistant low-silica zeolite comprises mixing a solution containing an aluminate with another solution containing a silicate, allowing the resulting mixture to gel, and aging the resulting gel, at the temperature of from 0.degree. C. to 60.degree. C., to prepare a slurry having a viscosity ranging from 10 to 10000 cp and containing amorphous aluminosilicate having a specific surface area of not less than 10 m.sup.2 /g with an SiO.sub.2 /Al.sub.2 O.sub.

Abstract: A PSA process for the separation of a gas flow containing essentially oxygen and nitrogen by preferential adsorption of the nitrogen, at a high adsorption pressure, on at least one bed of adsorbent material inserted in at least one separation zone. The material preferentially adsorbs nitrogen. Each bed of adsorbing material is subjected to successive separation cycles. Each separation cycle comprises at least: a purge phase comprising a desorption of the nitrogen adsorbed on the adsorbing material at a low desorption pressure below the high adsorption pressure, and a supply phase comprising introduction of the gaseous flow at a supply temperature (T.sub.sup) into the separation zone with passage from the low desorption pressure to the high adsorption pressure. The supply temperature (T.sub.sup) of the gaseous flow to be separated is regulated and the high adsorption pressure is adjusted.

Abstract: The invention comprises a PSA apparatus for the separation of a heavy component from a light component in a feed stream. The apparatus includes an adsorbent bed comprising either a mixture of adsorbents or composite adsorbent particles wherein each particle comprises two or more adsorbents. At least one of the adsorbents is comparatively weak and the other is comparatively strong. Another embodiment of the invention is a PSA prepurifier having a bed of adsorbent material which comprises a mixture of, or composite adsorbent particles wherein each particle comprises at least two adsorbents, at least one of the adsorbents being comparatively strong and at least another of the adsorbents being comparatively weak.

Abstract: For the separation of nitrogen from oxygen in air, an adsorbent is used which preferentially adsorbs the nitrogen. The adsorbent is a heterogeneous zeolite whose particles have a distribution of the capacity to adsorb nitrogen relative to oxygen, with a ratio (.sigma..sub.c /.mu..sub.c) comprised between 0.02 and 0.15, and/or having a distribution of selectivity of adsorption of nitrogen relative to oxygen with a ratio (.sigma..sub.s /.mu..sub.s) comprised between 0.02 and 0.25.

Abstract: A method of processing semiconductor manufacturing exhaust gases for recovering at least hexafluoroethane in which a feed stream composed of the exhaust gases is passed through an adsorbent bed selected to adsorb oxygen, and also nitrogen if present, but not to appreciably adsorb the hexafluoroethane. As a result, a product stream, discharged from the adsorbent bed, has a higher concentration of hexafluoroethane than in the feed stream. In one embodiment, only a single adsorbent such as carbon molecular sieve is provided to adsorb the oxygen or a modified 4A zeolite could be used to adsorb both oxygen and nitrogen. When nitrogen is a potential constituent, layers of carbon molecular sieve and zeolite are provided to adsorb the oxygen and then the nitrogen, respectively. A third adsorbent, preferably 5A zeolite may be provided in addition to the foregoing two adsorbents to also adsorb any carbon tetrafluoride produced as a by-product.

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: 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: An adsorbent for separating nitrogen from a feed gas containing at least one other gas having molecular dimensions equal to or larger than methane, the adsorbent comprising clinoptilolite having a sodium ion content of at least 17 equivalent percent of the total ion exchangeable cations and optionally one or more non-univalent cations, which if present comprise in total less than 12 equivalent percent of the total ion exchangeable cations, the balance, if any, being one or more non-sodium univalent cations.

Abstract: Air is supplied along a pipeline to an apparatus for separating an oxygen-enriched gas stream from the air by vacuum swing adsorption. The oxygen-enriched gas stream is supplied to a burner which fires into a furnace. A hot gas stream leaves the furnace through an outlet. Steam is raised from the hot gas in a waste heat boiler. Steam so raised flows through one or more of the eductors to draw through a pipeline the vacuum necessary for the operation of the vacuum swing adsorption apparatus.

Abstract: Barium-exchanged ETS-4 shows particular utility in gas separation processes involving the separation of nitrogen from a mixture of the same with methane.

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: Each adsorber (1, 2) is dimensioned in such a way that it operates in substantially adiabatic mode and its production dead volume (27), which is the free volume in permanent communication with the outlet side end of the mass of adsorbent (6), is between about 10% and 60% of the volume of the mass of adsorbent. Oxygen may thus be produced from atmospheric air.

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: The present invention relates to binder-free molecular sieve zeolite granules of lithium zeolite A and lithium zeolite X, a process for preparing these molecular sieve zeolite granules and their use for preparing nitrogen or oxygen from air by pressure swing adsorption.

Abstract: The present invention relates to new crystalline zeolite SSZ-39 prepared using a cyclic or polycyclic quaternary ammonium cation templating agent.

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: This invention comprises a method and apparatus for obtaining from air an oxygen enriched gas mixture containing at least 40 mole % nitrogen. The apparatus comprises a gas turbine, an oxygen separation unit which is in fluid communication with the turbine air compressor and means for maintaining a proper mass balance tolerance between the turbine compressor/unit and the turbine energy production unit.This invention comprises a method and apparatus for recovering large quantities of an oxygen enriched gas from the volume of a compressed air stream produced by a gas turbine by compensation of the mass loss to the energy production unit section thereof by providing means for maintaining the turbine in proper mass and thermal balance as the turbine is utilized to provide the duty/power requirements of a process which utilizes the oxygen enriched gas stream as a reactant.

Abstract: An alternating pressure apparatus for obtaining oxygen from the air has two adsorbers to which an air blower for adsorption air and a vacuum pump stand for desorption are connected. The vacuum pump stand has two vacuum pumps in tandem. In a partial load operation characterized by low O.sub.2 removal; and during the lower pressure equalization of the adsorbers, the vacuum pump stand is connected to the air blower in that in each case the vacuum valve, connecting one adsorber to the vacuum pump stand, and the air valve, connecting the same adsorber to the air blower, are opened at the same time.

Abstract: An alternating pressure apparatus for obtaining oxygen from the air has two adsorbers to which an air blower for adsorption air and a vacuum pump stand for desorption are connected. The vacuum pump stand has two vacuum pumps in tandem. The second vacuum pump in the direction of flow is configured as a rotary piston pump with preliminary inlet cooling for the defined inflow of outside air at atmospheric pressure. The inlet of the second vacuum pump is connected to the outlet of the first vacuum pump without the use of gas cooling by water injection or by a heat exchanger. The alternating pressure apparatus operates with a desorption pressure between 300 mbar and 500 mbar.

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 the separation of a gas mixture containing oxygen and nitrogen, including bringing the mixture into contact in an adsorption zone with a first selective adsorbent for nitrogen of faujasite type exchanged to at least 80% with lithium, in which the Si/Al ratio is lower than 1.5 and a second selective adsorbent for nitrogen of zeolite type exchanged with divalent cations such as the alkaline-earth metal or transition metal cations. The second adsorbent is characterized by a nitrogen adsorptivity C.sub.2 lower than the nitrogen adsorptivity C.sub.1 characterizing the first adsorbent, and an adsorption selectivity for nitrogen in relation to oxygen (1.times.10.sup.5 Pa, 20.degree. C.) higher than or equal to 3.

Abstract: A process for the purification of a solution of lithium salts contaminated by metallic cations, comprising (i) passing the solution to be purified through an exchange region packed with a material suitable for the exchange of Li.sup.+ cations by contaminating metallic cations, this material being initially charged more than 95% with Li.sup.+ cations and having a better affinity for the contaminating metallic cations than for Li.sup.+ cations, so as to fix all of the contaminating metallic cations on the material by replacement of Li.sup.+ cations, whereby the solution of lithium salts recovered at the outlet of the exchange zone is stripped of contaminating metallic cations; and (ii) regenerating the material by replacement of the metallic cations fixed on the material with Li.sup.+ cations.

Abstract: An acoustic oxygen sensor is provided which can be used in the output lines leading from the sieve beds. This sensor can be used in communication with a microprocessor to control the production and evacuation cycles of the sieve beds, i.e., for example to determine the period for which a bed is supplied with compressed air and communicates with the reservoir as well as to determine the pressure of the compressed air and to determine the amount of time that the product gas is fed through the flow equalization path to supply an aliquot of purging gas to a used bed. In the feedback loop, the microprocessor utilizes the measured oxygen concentration and flow rate to optimize the settings necessary to achieve maximum oxygen concentration and flow rate efficiency. Since the microprocessor has the ability to make incremental changes and compare relative values, the optimum values can be determined empirically eliminating the need to perform complex theoretical calculations.

Abstract: Process for the separation of the hydrogen contained in a gas mixture contaminated by carbon monoxide and containing at least one other impurity chosen from the group consisting of carbon dioxide and saturated or unsaturated, linear, branched or cyclic C.sub.1 -C.sub.8 hydrocarbons, comprising bringing the gas mixture to be purified into contact, in an adsorption region, with at least:one first adsorbent selective at least for carbon dioxide and for C.sub.1 -C. hydrocarbons andone second adsorbent which is a zeolite of faujasite type exchanged to at least 80% with lithium, the Si/Al ratio of which is less than 1.5, in order to remove at least carbon monoxide (CO).

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 oxygen concentrator is provided which has a first molecular sieve bed connected to a four-way valve (i.e., a cross-over valve) which either joins the sieve bed to a pressurized air source (compressed air) or alternatively vents it to atmosphere. A second molecular sieve bed is also joined to the four-way valve in a corresponding manner. The sieve beds are joined at the outlet end to a product reservoir. The sieve beds are also in fluid communication at the outlet end by a pressure equalization flow path. A concentration equalization valve regulates the flow in the pressure equalization flow path. In accordance with the present invention, the microprocessor uses a closed-loop feedback circuit to evaluate the amount of time that the output product gas is allowed to flow into the used sieve bed. Specifically, an incremental step advance is used assuming a peak value of the time of flow one direction as compared to the time of flow in the second direction.

Abstract: Applicant has discovered a new zeolite containing composition and a process for preparing the same. The composition is unique in that the zeolite crystals making up one layer of the composition pack in a manner such that the composition is essentially continuous with no large scale voids even when the zeolite layer is <10 .mu.m thick. Thus, the present invention is directed toward a composition comprised of a porous substrate and a layer of zeolite crystals wherein said layer of zeolite crystals is a polycrystalline layer with at least 99% of said zeolite crystals having at least one point between adjacent crystals that is .ltoreq.20 .ANG. and wherein at least 90% of said crystals have widths of from about 0.2 to about 100 microns (preferably about 2 to about 50 microns) and wherein at least 75% of said crystals have a thickness of within 20% of the average crystal thickness. Preferably the composition has at most 1 Volume % voids in the zeolite layer. Use of the composition is also described.

Abstract: A PSA process for the separation of a gaseous flow containing essentially oxygen and nitrogen, such as air, by preferential adsorption of the nitrogen on at least one bed of a thickness (e) of an adsorbent material of mean granulometry (d) in at least one separation zone, in which there is selected a thickness (e) of the adsorbent bed such that: ##EQU1## e and d being expressed in mm.

Abstract: A rotary valve system which includes of a pair of valve assemblies each of which has valve parts with flat faces which, when pressed together and rotated, provide valving action between various ports incorporated in one valve part of each assembly. The first valve part of each assembly contains a circular array of through openings, each of which is connected to a conduit. The second valve part of each assembly contains several passages which provide communication between various openings of the first valve part and valve apertures located in the second valve part of each assembly. The second valve part of each assembly also contains one or more passages which provide communication between members of one or the other array of openings. The valve system can be effectively used to automate operation of a gas or liquid adsorption system comprising two or more adsorption vessels, the number of vessels being equivalent to the total number of openings in either array.

Abstract: In the pressure swing adsorption of nitrogen from gas mixtures with less polar gas components at temperatures of between 20.degree. and 50.degree. C., wherein the gas mixture is passed through an adsorber which is filled with packings of zeolite pellets and has an inlet zone and an outlet zone, the improvement which comprises providing at least two packings in the adsorber, a packing of Li-zeolite X in the inlet zone of the adsorber and a packing of at least one of Ca-zeolite A and Ca-zeolite X in the outlet zone of the adsorber.

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: A crystalline zeolite X adsorbent comprising a crystalline zeolite X having an SiO.sub.2 /A.sub.2 O.sub.3 molar ratio of not larger than 3.0, where lithium cations associated with an AlO.sub.2 tetrahedron unit are 80 to less than 88 mol % of the total cations and the content of alkaline earth metal cations is from 0.5 to less than 4.6 mo % is produced by ion-exchanging with lithium cations at least 90 mol % of the cations associated with an Al.sub.2 O.sub.3 tetrahedron unit of a crystalline zeolite X having an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio of not larger than 3.0, ion-exchanging the crystalline zeolite X again with an aqueous solution of mixed salts of an alkali metal salt and an alkaline earth metal salt to decrease the lithium cations associated with the AlO.sub.2 tetrahedron unit to 80 to less than 88 mol %, followed by washing and drying, and activating the crystalline zeolite X.

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: An apparatus for providing oxygen-enriched air at a first pressure and at a second pressure, the second pressure being greater than the first pressure. The apparatus comprises, in combination, a pressure swing adsorption system and a pressure intensifier. The pressure swing adsorption system for enriching the oxygen content of air has a pressure of at least the first pressure. The pressure swing adsorption system is adapted to provide oxygen-enriched air to a first outlet at the first pressure and to provide oxygen-enriched air to a pressure intensifier at the first pressure. The pressure intensifier pressurizes the oxygen-enriched air and provides the oxygen-enriched air to a second outlet at the second pressure.