US 4,381,189 AGranted

Pressure swing adsorption process and system

AssigneeUnion Carbide Corporation

InventorAndrija Fuderer

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Abstract

Bed utilization and product recovery are enhanced in pressure swing adsorption operations, especially for high pressure applications, by terminating cocurrent depressurization at a relatively high intermediate pressure level. Additional void space gas is released from each main adsorption bed by partial countercurrent depressurization prior to conventional countercurrent blowdown. Such additional gas is passed to a satellite bed adapted for simultaneous release of gas from its discharge end, thereby cocurrently depressurizing said satellite bed from said intermediate pressure level, with the thus-released gas being passed to the discharge end of another satellite bed or beds and/or another main bed or beds for pressure equalization and/or purging purposes. The satellite bed is one of a satellite group of adsorption beds containing a lesser number and smaller beds than in said main bed system, the satellite beds not being operated above said intermediate pressure level.

Claims41

Dependent claims

In an adiabatic pressure swing adsorption process for selectively adsorbing at least one gas component from a feed gas mixture in a main multiple adsorption bed system in which each main bed undergoes the processing cycle of (a) introduction of feed gas to the bed inlet end at a superatmospheric adsorption pressure with discharge of unadsorbed effluent from the discharge end thereof;

(b) partial cocurrent depressurization of said bed with release of void space gas from the discharge end of the bed;
(c) introduction of the released void space gas to the discharge end of an adsorption bed(s), initially at lower pressure to equalize the pressure therebetween;
(d) release of gas from the inlet end of the bed partially depressurized during said cocurrent depressurization step (b) above for countercurrent blowdown to its desorption pressure;
(e) repressurization of the purged bed to the adsorption pressure;
and (f) repetition of the cycle of steps (a)-(e) with additional quantities of feed gas, the improvement comprising terminating said cocurrent depressurization at an intermediate pressure such that the ratio of adsorption pressure/intermediate pressure is less than about 5/1, and
(i) releasing void space gas from the inlet end of said main bed for partial countercurrent depressurization thereof prior to said countercurrent blowdown of step (d) above;
(ii) introducing the released void space gas of step (i) above to the inlet end of a satellite bed at about said intermediate pressure, said satellite bed being one of a satellite group of adsorption beds containing a lesser number and smaller beds than in said main bed system;
and
(iii) releasing gas from the discharge end of said satellite bed,
whereby main bed utilization is enhanced, thus enabling reduced bed volume and less adsorbent to be employed, while product recovery is also enhanced.

7 more elements

An improved adiabatic pressure swing adsorption system having adsorbent beds for selectively adsorbing at least one gas component from a feed gas mixture comprising:

(a) a main multiple adsorption bed system of at least four main beds having means on a cyclic basis for (1) withdrawing product effluent from each bed at superatmospheric adsorption pressure, (2) releasing void space gas from the discharge end thereof for passage to another bed for pressure equalization therebetween, (3) releasing gas from the inlet end thereof for countercurrent blowdown to desorption pressure, (4) passing purge gas therethrough, and (5) repressurizing each said bed;
(b) a satellite group of adsorption beds containing a lesser number and smaller beds than in said main bed system, each satellite bed having means, on a cyclic basis, for (1) releasing gas from the discharge end of said bed for cocurrent depressurization from an intermediate pressure for pressure equalization and/or to provide purge to other satellite bed(s) and to a bed(s) in said main bed system, (2) releasing gas from the inlet end thereof for countercurrent blowdown to desorption pressure, and (3) purging and repressurizing said bed to said intermediate pressure;
and
(c) conduit means for passing void space gas released by partial countercurrent depressurization, on a cyclic basis and upon completion of the release of gas from the discharge end of a main bed at an intermediate pressure such that the ratio of adsorption pressure/intermediate pressure is less than about 5/1, from the inlet end of each main bed to a satellite bed adapted for the simultaneous release of gas from the discharge end thereof to provide said pressure equalization and/or purge, said intermediate pressure of the main bed being also said intermediate pressure of the satellite bed,
whereby cocurrent depressurization of the main bed can be terminated at a relatively high intermediate pressure level, said satellite bed system enabling the bed volume and adsorbent for the overall system, and the weight of steel needed for the main beds to be appreciably reduced, while enhancing the recovery of product from the overall system.

2 more elements

Dependencies are inferred from the claim text.