Abstract: A PSA, especially VSA, plant for separating a gas stream, operating in a production cycle and comprising at least one adsorber, preferably two or three adsorbers, and several valves having long and heterogeneous operating times. More specifically, the average operating time (&mgr;) of the valves is such that: 0.5 s<&mgr;<2 s and the operating time (&Dgr;t) of each of the valves is such that: &mgr;−x<&Dgr;t<&mgr;+x, with 0.1 s<x<0.5 s. The invention also relates to the use of such a PSA plant for producing a gas stream rich in oxygen, in nitrogen or in hydrogen, particularly a stream comprising more than 80% oxygen, which is then sent to an oxygen-consuming plant chosen from a combustion furnace, a paper-pulp manufacturing unit and a water treatment unit.

Abstract: The invention relates to a process for controlling a PSA, especially VSA, plant for separating a gas stream, in particular a gas stream containing nitrogen and at least one less polar gaseous component, especially oxygen and/or hydrogen. The PSA plant operates in a production cycle and has one or more adsorbers, each production cycle comprising at least one feed step of feed duration (TA), which comprises introducing the gas stream to be separated into an adsorber; at least one production step, which comprises recovering a stream of gas produced at a prefixed production pressure (PP) and with a prefixed nominal production output (DN); and at least one pumping step of pumping duration (TP); which comprises extracting a gas stream from at least one adsorber.

Abstract: According to this process, in the case of a reduction in the production rate, the maximum pressure PM of the cycle is lowered and the ratio of this maximum pressure to the minimum pressure Pm of the cycle is reduced, in particular by altering the durations of compression and decompression stages. The process is applicable to the production of oxygen at variable rate.

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: 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: 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: 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: 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: 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 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.