Pressure swing adsorption process and system

Claim 2

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.

Claim 3

The process of claim 1 in which said satellite bed provides gas for both pressure equalization and purging purposes.

Claim 4

The process of claim 2 in which said intermediate pressure is such that said pressure ratio is less than about 3/1.

Claim 5

The process of claim 3 in which the adsorption pressure is from about 20 to about 70 bar.

Claim 6

The process of claim 4 in which said unadsorbed effluent comprises hydrogen.

Claim 7

The process of claim 2 in which said main bed system has from about 4 to 10 adsorption beds.

Claim 8

The process of claim 6 in which said intermediate pressure is such that said pressure ratio is less than about 3/1, the adsorption pressure is from about 30 to about 70 bar, and said unadsorbed effluent comprises hydrogen.

Claim 9

The process of claim 3 in which the main adsorption bed system has seven beds and two pressure equalizations by cocurrent depressurization of a main bed, and said satellite bed system has two beds, with gas being released from each cocurrently, in conjunction with said partial countercurrent depressurization of the main bed, for said pressure equalization and purge purposes.

Claim 10

The process of claim 3 in which the main adsorption bed system has eight beds and two cocurrent depressurization-pressure equalization steps, and the satellite bed system has two beds.

Claim 11

The process of claim 3 in which the main adsorption bed system has nine beds and two cocurrent depressurization-pressure equalization steps, and said satellite bed system has three beds.

Claim 12

The process of claim 3 in which the main adsoprtion bed system has ten beds and two cocurrent depressurization-pressure equalization steps, and said satellite bed system has five beds, with gas released cocurrently therefrom being employed for two pressure equalizations and for purging.

Claim 13

The process of claim 1 in which said satellite bed provides purging gas.

Claim 14

The process of claim 12 in which said intermediate pressure is such that said pressure ratio is less than about 3/1.

Claim 15

The process of claim 13 in which the adsorption pressure is from about 20 to about 70 bar.

Claim 16

The process of claim 14 in which said unadsorbed effluent comprises hydrogen.

Claim 17

The process of claim 12 in which said main bed system has from about 4 to 10 adsorption beds.

Claim 18

The process of claim 16 in which said intermediate pressure is such that said pressure ratio is less than about 2/1, and the adsorption pressure is from about 20 to about 70 bar.

Claim 19

The process of claim 16 in which the main adsorption bed system has four beds and one pressure equalization by cocurrent depressurization, and said satellite bed system has two beds, with gas released from each cocurrently for purging in conjunction with said partial countercurrent depressurization of said main bed.

Claim 20

The process of claim 16 in which said main absorption bed system has from five to seven beds, and said satellite bed system has two beds.

Claim 21

The process of claim 16 in which said main adsorption bed system has eight or nine beds.

Claim 22

The process of claim 20 in which said main bed system employs three pressure equalization steps in its processing cycle, and said satellite bed system has three beds, with gas released from each cocurrently being used for compression of blowdown gas and for purging in conjunction with said partial countercurrent depressurization of said main bed.

Claim 23

The process of claim 16 in which said main adsorption bed system has ten beds.

Claim 24

The process of claim 22 in which said main bed system employs three pressure equalization steps, and said satellite bed system has four beds, with gas released from each cocurrently being used for compression of blowdown gas and for purging purposes.

Claim 25

The process of claim 1 and including: (iv) introducing the gas released from said satellite bed to the discharge end of another main bed(s) and another satellite bed(s) to pressure equalize and/or purge said beds; (v) releasing gas from the inlet end of said satellite bed for countercurrent blowdown to desorption pressure; (vi) introducing gas from another satellite bed to the discharge end of said satellite bed at desorption pressure for the purging thereof, with purge gas discharge through the inlet thereof; and (vii) repressurizing said satellite bed from its desorption pressure to said intermediate pressure.

Claim 26

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.

Claim 27

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.

Claim 28

The adsorption system of claim 25 in which said satellite bed is adapted to release gas from its discharge end for both pressure equalization and/or for providing purge.

Claim 29

The adsorption system of claim 26 and including control means adapted to ensure completion of the release of gas from the discharge end of said main bed at an intermediate pressure such that said pressure ratio is in the range of from less than about 2/1 to less than about 3/1, and passage of void space gas from the inlet end thereof to a satellite bed at such intermediate pressure.

Claim 30

The adsorption system of claim 27 in which said main bed system has from about 6 to 10 adsorption beds.

Claim 31

The adsorption system of claim 28 in which said main adsorption bed system has seven beds, each adapted for two pressure equalizations by cocurrent depressurization, and said satellite bed system has two beds, with gas released from each cocurrently for pressure equalization and for purge in conjunction with said partial countercurrent depressurization of said main bed.

Claim 32

The adsorption system of claim 28 in which said main adsorption bed system has eight beds, each adapted for three cocurrent depressurization, pressure equalizations, and said satellite bed systems has three beds.

Claim 33

The adsorption system of claim 28 in which said main bed system has nine beds, each adapted for two cocurrent depressurization, pressure equalizations, and said satellite bed system has three beds.

Claim 34

The adsorption system of claim 28 in which said main bed system has ten beds, adapted for two cocurrent depressurization, pressure equalizations, and said satellite bed system has five beds.

Claim 35

The adsorption system of claim 25 in which said satellite bed is adapted to release gas from its discharge end for providing purge, but not for pressure equalization purposes.

Claim 36

The adsorption system of claim 33 and including control means adapted to ensure completion of the release of gas from the discharge end of said main bed at an intermediate pressure such that said pressure ratio is less than about 3/1, and passage of void space gas from the inlet end thereof to a satellite bed at such higher intermediate pressure.

Claim 37

The adsorption system of claim 34 in which said main bed system has from about 4 to 10 beds.

Claim 38

The adsorption system of claim 35 in which the main adsorption system has four beds, each adapted for one pressure equalization by cocurrent depressurization, and said satellite bed system has two beds, with gas released from each cocurrently for purge in conjunction with said partial countercurrent depressurization of said main bed.

Claim 39

The adsorption system of claim 35 in which said main adsorption bed system has from five to seven beds, and said satellite bed system has two beds.

Claim 40

The adsorption system of claim 35 in which said main adsorption bed system has eight or nine beds.

Claim 41

The adsorption system of claim 38 in which said main bed system is adapted for three cocurrent depressurization, pressure equalizations, and said satellite bed system has three beds, and including means for passing gas released from each cocurrently for compression of blowdown gas and for purging in conjunction with said partial countercurrent depressurization of said main bed.

Claim 42

The adsorption system of claim 35 in which said main adsorption bed system has ten beds.

Claim 43

The adsorption system of claim 40 in which said main bed system is adapted for three cocurrent depressurization, pressure equalizations, and said satellite bed system has four beds, and including means for passing gas released from each cocurrently for compression of blowdown gas and for purging in conjunction with said partial countercurrent depressurization of said main bed.