A process for separating h2 from a gas mixture

Patent metadata

Field	Value
Publication number	US-2024075423-A1
Application number	US-202118038229-A
Country	US
Kind code	A1
Filing date	Nov 26, 2021
Priority date	Nov 27, 2020
Publication date	Mar 7, 2024
Grant date	—

Abstract

The present invention relates a process for separating H2, preferably both H2 and CH4, from a gas mixture comprising H2 and CH4 by means of a series of selective membrane units that avoids compressors and vacuums as well as an apparatus for carrying out said separation.

First claim

1 .- 21 . (canceled)

22 . A process for separating H 2 from a gas mixture comprising H 2 and CH 4 , the process comprising
(i) a separation stage comprising
(i.1) passing a feed gas stream F 1 comprising H 2 and CH 4 at a molar ratio n(H 2 ):n(CH 4 )=x(F 1 ), 0<x(F 1 )≤0.5, through a membrane unit A comprising at least one membrane, the at least one membrane having a H 2 /CH 4 selectivity of at least 10, at a pressure ratio φ across said at least one membrane, calculated as (pressure of feed gas stream F 1 /pressure of permeate gas stream P 1 ) at constant temperature, of greater than 1, obtaining
a permeate gas stream P 1 comprising H 2 and CH 4 at a molar ratio n(H 2 ):n(CH 4 )=x(P 1 ); x(P 1 )>x(F 1 ); and
a retentate gas stream R 1 comprising H 2 and CH 4 at a molar ratio n(H 2 ):n(CH 4 )=x(R 1 ); x(R 1 )<x(F 1 );

(i.2) passing retentate gas stream R 1 as a further feed gas stream F 2 through a further separation stage, F 2 having the same composition as R 1 ;
(ii) a further separation stage comprising
(ii.1) passing F 2 through a membrane unit B comprising at least one membrane, the at least one membrane having a H 2 /CH 4 selectivity of at least 10, at a pressure ratio φ across said at least one membrane, calculated as (pressure of feed gas stream F 2 /pressure of permeate gas stream P 2 ) at constant temperature, of greater than 1, obtaining
a permeate gas stream P 2 comprising H 2 and CH 4 at a molar ratio n(H 2 ):n(CH 4 )=x(P 2 ) of at least 1.4; x(P 2 )>x(F 2 ); and
a retentate gas stream R 2 comprising H 2 and CH 4 at a molar ratio n(H 2 ):n(CH 4 )=x(R 2 ) of <0.17; x(R 2 )<x(F 2 );

(ii.2) optionally passing retentate gas stream R 2 as a further feed gas stream F 3 through a further separation stage (iii), F 3 having the same composition as R 2 ;
(iii) an optional further separation stage comprising
(iii.1) passing F 3 through a further membrane unit C comprising at least one membrane, the at least one membrane having a H 2 /CH 4 selectivity of at least 10, at a pressure ratio φ across said at least one membrane (calculated as the (pressure of feed gas stream F 3 /pressure of permeate gas stream P 3 ) at constant temperature), of greater than 1, obtaining
a permeate gas stream P 3 comprising H 2 and CH 4 at a molar ratio n(H 2 ):n(CH 4 )=x(P 3 ) of at least 0.39; x(P 3 )>x(F 3 ); and
a retentate gas stream R 3 comprising H 2 and CH 4 at a molar ratio n(H 2 ):n(CH 4 )=x(R 3 ) of ≤0.01.

23 . The process of claim 22 , wherein no vacuum apparatus or compressor is operated downstream of the membrane unit A in the obtainment of the permeate gas streams and/or retentate gas streams.

24 . The process of claim 22 , wherein the at least one membrane comprised in the respective membrane unit A, B and/or C has a H 2 /CH 4 selectivity of at least 10.

25 . The process of claim 22 , wherein according to (i.1) the pressure ratio φ across the at least one membrane comprised in membrane unit A, calculated as (pressure of feed gas stream F 1 /pressure of permeate gas stream P 1 ) at constant temperature, is of at least 4.

26 . The process of claim 22 , wherein the mole ratio x(F 1 ) is in the range of from 0.05 to 0.5.

27 . The process of claim 22 , wherein feed gas stream F 1 has pressure in the range of from 5 to 100 bar (abs); and
wherein the feed gas stream F 1 has a temperature in the range of from −30° C. to 60° C.

28 . The process of claim 22 , wherein the mole ratio x(P 1 ) is of at least 2.

29 . The process of claim 22 , wherein the permeate gas stream P 1 has a pressure in the range of from >1 to 50 bar(abs).

30 . The process of claim 22 , wherein the mole ratio x(R 1 ) is of at most 0.49, and wherein the retentate gas stream R 1 has a pressure in the range of from 29.5 to 75.5 bar (abs).

31 . The process of claim 22 , wherein according to (i.1) the flow rate ratio of feed gas F 1 to the retentate gas stream R 1 calculated as (flow rate F 1 /flow rate R 1 ) is in the range of from >1 to 2.

32 . The process of claim 22 , wherein according to (ii.1) the pressure ratio φ across the at least one membrane comprised in membrane unit B, calculated as (pressure of feed gas stream F 2 /pressure of permeate gas stream P 2 ) at constant temperature, is of at least 4.

33 . The process of claim 22 , wherein the mole ratio x(P 2 ) is of at least 1.5; and wherein the permeate gas stream P 2 has a pressure in the range of from >1 to 15 bar(abs).

34 . The process of claim 22 , wherein the mole ratio x(R 2 ) is of at most 0.15, and wherein the retentate gas stream R 2 has a pressure in the range of from 29 to 75 bar (abs).

35 . The process of claim 22 , wherein according to (ii.1) the flow rate ratio of feed gas F 2 to the retentate gas stream R 2 calculated as (flow rate F 2 /flow rate R 2 ) is in the range of from 1.05 to 2.

36 . The process of claim 22 , wherein according to (iii.1) the pressure ratio φ across the at least one membrane comprised in membrane unit C, calculated as (pressure of feed gas stream F 3 /pressure of permeate gas stream P 3 ) at constant temperature is of at least 20.

37 . The process of claim 22 , wherein the mole ratio x(R 3 ) is of at most 0.009, and wherein the retentate gas stream R 3 has a pressure in the range of from 28.5 to 74.5 bar (abs).

38 . The process of claim 22 , wherein according to (iii.1) the flow rate ratio of feed gas F 3 to the retentate gas stream R 3 calculated as (flow rate F 3 /flow rate R 3 ) is in the range of from 1.01 to 1.6.

39 . An apparatus for separating H 2 , from a gas mixture comprising H 2 and CH 4 , the apparatus comprising
(I) a unit comprising
(I.a) a feeding means for passing a feed gas stream F 1 comprising H 2 and CH 4 to a membrane unit A;
(I.b) the membrane unit A connected to the feeding means for passing a feed gas stream F 1 according to (I.a), said membrane unit comprising at least one membrane, the at least one membrane having a H 2 /CH 4 selectivity of at least 10;
(I.c) an exiting means connected to the membrane unit A, for removing a permeate gas stream P 1 from the membrane unit A;
(Id) an exiting means connected to the membrane unit A for removing a retentate gas stream R 1 from the membrane unit A;
(II) a unit comprising
(II.a) a feeding means, connected to the exiting means according to (Id), for passing the gas stream R 1 as a feed gas F 2 to a membrane unit B;
(II.b) the membrane unit B connected to the feeding means for passing a feed gas stream F 2 according to (II.a), said membrane unit comprising at least one membrane, the at least one membrane having a H 2 /CH 4 selectivity of at least 10;
(II.c) an exiting means connected to the membrane unit B for removing a permeate stream P 2 from the membrane unit B;
(II.d) an exiting means connected to the membrane unit B for removing a retentate stream R 2 from the membrane unit B;
(III) optionally a unit comprising
(III.a) a feeding means, connected to the exiting means according to (II.d), said feeding means for passing the gas stream F 3 to a membrane unit C;
(III.b) the membrane unit C connected to the feeding means according to (III.a), said membrane unit comprising at least one membrane, the at least one membrane having a H 2 /CH 4 selectivity of at least 10;
(III.c) an exiting means connected to the membrane unit C for removing a permeate stream P 3 from the membrane unit C;
(III.d) an exiting means connected to the membrane unit C for removing a retentate stream R 3 from the membrane unit C

Assignees

• Basf Se

Inventors

• Strobel Paul-Vinzent
• Kappert Emiel Jan
• Ehrhardt Kai Rainer
• Vargas Schmitz Juergen Jose
• Gall Martin

Classifications

• B01D53/226 Primary

  in serial connexion · CPC title

• C01B3/501 Primary

  by diffusion · CPC title

• B01D2053/223

  with hollow tubes · CPC title

• B01D2256/16

  Hydrogen · CPC title

• B01D2257/7025

  Methane · CPC title