Process for separation of gases
The invention relates to a specific apparatus, more particularly a chain of gas separation membrane modules, for separation of gas mixtures into two fractions each of elevated purity.
1. An apparatus for separating gases, comprising:
membrane separation stages; and,
a compressor, a vacuum pump, or both,
wherein the membrane separation stages comprise a feed stream separation stage, a retentate separation stage, and a permeate separation stage:
the feed stream separation stage is configured to separate a feed stream comprising at least two components into a first permeate stream and a first retentate stream,
the retentate separation stage is configured to divide the first retentate stream into a second permeate stream and a second retentate stream,
wherein
the second permeate stream is supplied to the feed stream, and the second retentate stream is withdrawn as a product, and
the permeate separation stage is configured to divide the first permeate stream into a third retentate stream and a third permeate stream,
wherein
the third retentate stream is supplied to the feed stream, and the third permeate stream is withdrawn as a product,
the apparatus is configured not to subject the first permeate stream to any recompression,
the feed stream separation stage comprises a gas separation membrane module having a mixed gas selectivity of at least 30,
the apparatus is configured such that a gas volume recycled in the second permeate stream and in the third retentate stream totals less than 60% by volume of a crude gas stream,
the apparatus is configured to increase a concentration of at least one permeate gas of the feed stream separation stage, after recycling of the second permeate stream and of the third retentate stream, in the feed stream, compared to a concentration in the crude gas stream.
2. The apparatus of claim 1 ,
wherein
the apparatus is configured to pass the second permeate stream and the third retentate stream along a suction side of the compressor.
3. The apparatus of claim 1 , comprising:
a multistage compressor as a compressor.
4. The apparatus of claim 3 , wherein the apparatus is configured to introduce the second permeate stream, the third retentate stream, or both into the compressor between two compression stages.
5. The apparatus of claim 1 , wherein the apparatus is configured to pass at least one selected from the group consisting of the first retentate stream, the second retentate stream, and the third retentate stream through a pressure-reducing valve.
6. The apparatus of claim 1 , wherein the gas separation membrane module in at least one of the membrane separation stages has a mixed gas selectivity of at least 35.
7. The apparatus of claim 1 , wherein at least one of the membrane separation stages comprises more than one gas separation membrane module, wherein the modules are connected in parallel, in series, or in parallel and in series.
8. The apparatus of claim 1 , wherein at least one of the membrane separation stages comprises a gas separation membrane module comprising a hollow fiber membrane, a flat membrane, or both.
9. The apparatus of claim 1 , wherein a separation-active layer of a membrane comprises a material that is an amorphous or semicrystalline polymer.
10. The apparatus of claim 1 , wherein the apparatus is configured to discharge at least 95% of a retentate component of the feed stream separation stage which has been introduced into the apparatus with the crude gas stream via the second retentate stream.
11. The apparatus of claim 1 , wherein the apparatus is configured to discharge not more than 5% of a retentate component of the feed stream separation stage introduced into the apparatus with the crude gas stream via the third permeate stream.
12. A process for separating a gas mixture stream comprising:
separating the gas mixture with an apparatus comprising:
membrane separation stages; and
a compressor, a vacuum pump, or both,
wherein the membrane separation stages comprise a feed stream separation stage, a retentate separation stage, and a permeate separation stage:
the feed stream separation stage is configured to separate the gas mixture stream into a first permeate stream and a first retentate stream,
the retentate separation stage is configured to divide the first retentate stream into a second permeate stream and a second retentate stream,
wherein the second permeate stream is supplied to the gas mixture stream, and the second retentate stream is withdrawn as a product, and the permeate separation stage is configured to divide the first permeate stream into a third retentate stream and a third permeate stream,
wherein the third retentate stream is supplied to the gas mixture stream, and
the third permeate stream is withdrawn as a product,
the apparatus is configured not to subject the first permeate stream to any recompression,
the feed stream separation stage comprises a gas separation membrane module having a mixed gas selectivity of at least 30,
the apparatus is configured such that a gas volume recycled in the second permeate stream and in the third retentate stream totals less than 60% by volume of a crude gas stream,
the apparatus is configured to increase a concentration of at least one permeate gas of the feed stream separation stage, after recycling of the second permeate stream and of the third retentate stream, in the feed stream, compared to a concentration in the crude gas stream, and
wherein the third permeate stream comprises more than 95 vol % of a retentate gas of the feed stream separation stage in the gas mixture stream, and the second retentate system comprises more than 95 vol % of a permeate gas of the feed stream separation stage in the gas mixture stream.
13. The process of claim 12 , wherein
the crude gas stream comprises:
at least one of
a crude biogas and
a crude natural gas.
14. The process of claim 12 , wherein the separating comprises adjusting a pressure on a permeate side of the feed stream separation stage with a pressure-reducing valve on a retentate side of the permeate separation stage, to from 1 to 30 bar.
15. The process of claim 14 , wherein the material is a polyimide of formula
wherein
each R is independently selected from the group consisting of
x and y are mol fractions,
0<x<0.5, and
1>y>0.5.
16. The process of claim 12 , wherein the separating comprises adjusting a pressure of the first and second retentate stream with a pressure-reducing valve in the second retentate stream, to from 1 to 100 bar.
17. The process of claim 12 , wherein a driving force is a partial pressure differential between a retentate side and a permeate side in the respective membrane separation stages,
wherein the partial pressure differential is generated by at least one selected from the group consisting of a compressor in the feed stream, a vacuum pump in the second permeate stream, a vacuum pump in the third permeate stream, and a permeate-side purge gas stream.
18. The process of claim 17 , wherein a pressure of the permeate side of the feed stream separation stage is greater than or equal to an ambient pressure,
the driving force comprises the ambient pressure or a reduce pressure at the permeate side of the permeate separation stage.
19. The apparatus of claim 1 , wherein the material is at least one selected from the group consisting of a polyimide, a polyamide, a polysulfone, a cellulose acetate, a cellulose acetate derivative, a polyphenylene oxide, a polysiloxane, a polymer with an intrinsic microporosity, a mixed matrix membrane, a facilitated transport membrane, a polyethylene oxide, and a polypropylene oxide.
20. The process of claim 13 , wherein the crude gas mixture consists essentially of carbon dioxide and methane.
21. The process of claim 12 , wherein the third permeate stream comprises more than 97 vol % of the carbon dioxide in the gas mixture stream.
22. The process of claim 12 , wherein the second retentate stream comprises more than 97 vol % of the methane in the gas mixture stream.
23. The process of claim 12 , wherein the crude gas stream comprises carbon dioxide and methane.
24. The process of claim 12 , wherein the crude gas stream comprises hydrogen and methane.
25. The process of claim 12 , wherein the crude gas stream comprises carbon monoxide and hydrogen.
26. The process of claim 12 , wherein the apparatus is configured to pass the second permeate stream and the third retentate stream along a suction side of the compressor.
27. The process of claim 12 , wherein the compressor is a multistage compressor.
28. The process of claim 12 , wherein the apparatus is configured to introduce the second permeate stream, the third retentate stream, or both into the multistage compressor between two compression stages.
29. The process of claim 12 , wherein the apparatus is configured to pass at least one selected from the group consisting of the first retentate stream, the second retentate stream, and the third retentate stream through a pressure-reducing valve.
30. The process of claim 12 , wherein the gas separation membrane module in at least one of the membrane separation stages having a mixed gas selectivity for carbon dioxide and methane of at least 35.
31. The process of claim 12 , wherein at least one of the membrane separation stages comprises more than one gas separation membrane module, wherein the modules are connected in parallel, in series, or in parallel and in series.
32. The process of claim 12 , wherein at least one of the membrane separation stages comprises a gas separation membrane module comprising a hollow fiber membrane, a flat membrane, or both.
33. The process of claim 12 , wherein a separation-active layer of a membrane comprises a material that is an amorphous or semicrystalline polymer.
34. A process for separating a gas mixture stream comprising methane and carbon dioxide, comprising:
separating the gas mixture with an apparatus comprising:
membrane separation stages; and,
a compressor, a vacuum pump, or both,
wherein the membrane separation stages comprise a feed stream separation stage, a retentate separation stage, and a permeate separation stage:
the feed stream separation stage is configured to separate a feed stream comprising at least two components into a first permeate stream and a first retentate stream,
the retentate separation stage is configured to divide the first retentate stream into a second permeate stream and a second retentate stream,
wherein the second permeate stream is supplied to the feed stream, and the second retentate stream is withdrawn as a product, and
the permeate separation stage is configured to divide the first permeate stream into a third retentate stream and a third permeate stream,
wherein the third retentate stream is supplied to the feed stream, and the third permeate stream is withdrawn as a product,
the apparatus is configured not to subject the first permeate stream to any recompression,
the feed stream separation stage comprises a gas separation membrane module having a mixed gas selectivity of at least 30,
the apparatus is configured such that a gas volume recycled in the second permeate stream and in the third retentate stream totals less than 60% by volume of a crude gas stream,
the apparatus is configured to increase a concentration of at least one permeate gas of the feed stream separation stage, after recycling of the second permeate stream and of the third retentate stream, in the feed stream, compared to a concentration in the crude gas stream.
35. The process of claim 34 , wherein the material is at least one selected from the group consisting of a polyimide, a polyamide, a polysulfone, a cellulose acetate, a cellulose acetate derivative, a polyphenylene oxide, a polysiloxane, a polymer with an intrinsic microporosity, a mixed matrix membrane, a facilitated transport membrane, a polyethylene oxide, and a polypropylene oxide.
36. The process of claim 35 , wherein the material is a polyimide of formula
wherein each R is independently selected from the group consisting of
x and y are mol fractions,
0<x<0.5, and
1>y>0.5.
37. The process of claim 34 , wherein the crude gas stream comprises at least one gas pair selected from the group consisting of:
carbon dioxide and methane;
hydrogen and methane;
carbon monoxide and hydrogen;
a crude biogas; and
a crude natural gas.
38. The process of claim 34 , wherein the crude gas stream consists essentially of at least one gas pair selected from the group consisting of:
carbon dioxide and methane;
hydrogen and methane;
carbon monoxide and hydrogen;
a crude biogas; and
a crude natural gas.
39. The process of claim 34 , wherein the third permeate stream comprises less than 5 vol. % of the retentate gas compared to the amount of said retentate gas originally introduced into the process with crude gas stream and that the second retentate stream comprises more than 95 vol. % of the retentate gas of the feed stream separation stage compared to the amount of said retentate gas originally introduced into the process with the crude gas stream.
40. The process of claim 39 , wherein a driving force is a partial pressure differential between a retentate side and a permeate side in the respective membrane separation stages, and
wherein the partial pressure differential is generated by at least one selected from the group consisting of a compressor in the feed stream, a vacuum pump in the second permeate stream, a vacuum pump in the third permeate stream, and a permeate-side purge gas stream.
41. The process of claim 39 , wherein a pressure of the permeate side of the feed stream separation stage is greater than or equal to an ambient pressure,
the driving force comprises the ambient pressure or a reduce pressure at the permeate side of the permeate separation stage.
42. The process of claim 39 , wherein the material is at least one selected from the group consisting of a polyimide, a polyamide, a polysulfone, a cellulose acetate, a cellulose acetate derivative, a polyphenylene oxide, a polysiloxane, a polymer with an intrinsic microporosity, a mixed matrix membrane, a facilitated transport membrane, a polyethylene oxide, and a polypropylene oxide.
43. The process of claim 34 , wherein the separating comprises adjusting a pressure of the first and second retentate stream with a pressure-reducing valve in the second retentate stream, to from 1 to 100 bar.
44. The process of claim 34 , wherein the separating comprises adjusting a pressure on a permeate side of the feed stream separation stage with a pressure-reducing valve on a retentate side of the permeate separation stage, to from 1 to 30 bar.
45. The process of claim 34 , wherein the gas separation membrane module in at least one of the membrane separation stages has a mixed gas selectivity of at least 35.
46. The process of claim 34 , wherein the gas separation membrane module in at least one of the membrane separation stages has a mixed gas selectivity of at least 45.
47. The process of claim 34 , wherein the apparatus comprises at least one gas separation membrane module comprising hollow polyimide fibers having a separation area of about 5 m 2 .
48. The process of claim 34 , wherein the apparatus is configured to pass the second permeate stream and the third retentate stream along a suction side of the compressor.
49. The process of claim 34 , wherein the compressor is a multistage compressor.
50. The process of claim 34 , wherein the apparatus is configured to introduce the second permeate stream, the third retentate stream, or both into the multistage compressor between two compression stages.
51. The process of claim 34 , wherein the apparatus is configured to pass at least one selected from the group consisting of the first retentate stream, the second retentate stream, and the third retentate stream through a pressure-reducing valve.
52. The process of claim 34 , wherein at least one of the membrane separation stages comprises more than one gas separation membrane module, wherein the modules are connected in parallel, in series, or in parallel and in series.
53. The process of claim 34 , wherein at least one of the membrane separation stages comprises a gas separation membrane module comprising a hollow fiber membrane, a flat membrane, or both.
54. The process of claim 39 , wherein a separation-active layer of a membrane comprises a material that is an amorphous or semicrystalline polymer.
55. The process of claim 39 , wherein the material is a polyimide of formula
wherein
each R is independently selected from the group consisting of
x and y are mol fractions,
0<x<0.5, and
1>y>0.5.
56. The apparatus of claim 1 , wherein the second retentate stream comprises more than 97 vol % of the methane in the gas mixture stream.
57. The apparatus of claim 1 , wherein the apparatus comprises at least one gas separation membrane module having a gas selectivity for methane and carbon dioxide of at least 45.
58. The apparatus of claim 1 , wherein the apparatus comprises at least one gas separation membrane module comprising hollow polyimide fibers having a separation area of about 5 m 2 .