Process for recovering semiconductor industry cleaning compounds
First Claim
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1. A process for separating a perfluoro compound from a second gas in a gas mixture, said process comprising the steps of:
- (a) providing a first membrane having a first feed side and a first permeate side, and being selective for said second gas over said perfluoro compound;
(b) passing said gas mixture across said first feed side;
(c) withdrawing from said first feed side a first residue stream depleted in said second gas and enriched in said perfluoro compound compared with said gas mixture;
(d) withdrawing from said first permeate side a first permeate stream enriched in said second gas and depleted in said perfluoro compound compared with said gas mixture;
(e) providing a second membrane having a second feed side and a second permeate side, and being selective for said second gas over said perfluoro compound;
(f) passing said first residue stream across said second feed side;
(g) withdrawing from said second feed side a second residue stream depleted in said second gas and enriched in said perfluoro compound compared with said first residue stream;
(h) withdrawing from said second permeate side a second permeate stream enriched in said second gas and depleted in said perfluoro compound compared with said first residue stream;
(i) passing said second residue stream to a condensation step carried out at a temperature no lower than about -30°
C. to liquefy at least a portion of said second residue stream, thereby forming a liquefied perfluoro compound product;
(j) recirculating said second permeate stream to said first feed side.
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Abstract
A process for separating perfluoro compound gas or vapor from another gas, typically nitrogen, in a gas mixture. The process involves a combination of membrane separation and condensation, and is particularly useful in the semiconductor industry, for treating exhaust gases from cleaning of chemical vapor deposition chambers. Operation of the condensation step at temperatures no lower than about -30° C. reduces the need for refrigeration equipment and controls the amount of gas dissolved in the recovered perfluoro compound.
57 Citations
71 Claims
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1. A process for separating a perfluoro compound from a second gas in a gas mixture, said process comprising the steps of:
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(a) providing a first membrane having a first feed side and a first permeate side, and being selective for said second gas over said perfluoro compound; (b) passing said gas mixture across said first feed side; (c) withdrawing from said first feed side a first residue stream depleted in said second gas and enriched in said perfluoro compound compared with said gas mixture; (d) withdrawing from said first permeate side a first permeate stream enriched in said second gas and depleted in said perfluoro compound compared with said gas mixture; (e) providing a second membrane having a second feed side and a second permeate side, and being selective for said second gas over said perfluoro compound; (f) passing said first residue stream across said second feed side; (g) withdrawing from said second feed side a second residue stream depleted in said second gas and enriched in said perfluoro compound compared with said first residue stream; (h) withdrawing from said second permeate side a second permeate stream enriched in said second gas and depleted in said perfluoro compound compared with said first residue stream; (i) passing said second residue stream to a condensation step carried out at a temperature no lower than about -30°
C. to liquefy at least a portion of said second residue stream, thereby forming a liquefied perfluoro compound product;(j) recirculating said second permeate stream to said first feed side. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A process for separating a perfluoro compound from a second gas in a gas mixture, said process comprising the steps of:
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(a) providing a first membrane having a first feed side and a first permeate side, and being selective for said second gas over said perfluoro compound; (b) passing said gas mixture across said first feed side; (c) withdrawing from said first feed side a first residue stream depleted in said second gas and enriched in said perfluoro compound compared with said gas mixture; (d) withdrawing from said first permeate side a first permeate stream enriched in said second gas and depleted in said perfluoro compound compared with said gas mixture; (e) passing said first residue stream to a condensation step carried out at a temperature no lower than about -30°
C. to liquefy at least a portion of said first residue stream, thereby forming a liquefied perfluoro compound product;(f) providing a second membrane having a second feed side and a second permeate side; (g) passing an uncondensed gas stream from said condensation step across said second feed side; (h) withdrawing from said second feed side a second residue stream depleted in said second gas and enriched in said perfluoro compound compared with said uncondensed gas stream; (i) withdrawing from said second permeate side a second permeate stream enriched in said second gas and depleted in said perfluoro compound compared with said uncondensed gas stream; (j) recirculating said second permeate stream to said first feed side; (k) recirculating said second residue stream to said condensation step. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71)
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Specification