Claims
- 1. A cryogenic distillation process for producing oxygen comprising:
- (a) withdrawing gaseous oxygen at a product pressure of up to about 10 ATA from a latent heat exchanger;
- (b) supplying a fraction of air that has been cleaned and cooled to near its dewpoint at an elevated pressure that is at least approximately 21/2 times the oxygen product pressure to an elevated pressure rectification column;
- (c) rectifying the elevated pressure air to a liquid N.sub.2 over-head product and an oxygen enriched liquid bottom product;
- (d) refluxing the elevated pressure rectifier by indirect heat exchange in said latent heat exchanger with boiling pressurized liquid oxygen, whereby said gaseous oxygen at product pressure is obtained;
- (e) supplying said liquid nitrogen, said oxygen enriched liquid, plus a remaining fraction of air at a high pressure that is at least 2 ATA lower than said elevated pressure to a cryogenic distillation apparatus;
- (f) distilling said fluids from step (e) so as to obtain low pressure liquid oxygen;
- (g) pressurizing said low pressure liquid oxygen for use in step (d), while precluding the requirement for a mechanical gaseous oxygen compressor.
- 2. The process according to claim 1 wherein the elevated pressure fraction of air comprises between 15 and 40% of the total air supplied to the process.
- 3. The process according to claim 2 wherein the cryogenic distillation apparatus is comprised of a dual pressure column.
- 4. The process according to claim 2 wherein the cryogenic distillation apparatus is comprised of a high pressure rectifier, a nitrogen rejection column and at least one additional column which separates argon from the oxygen.
- 5. The process according to claim 4 further comprising rectifying said supply fluids into liquid N.sub.2 and oxygen enriched liquid in said HP rectifier, distilling said oxygen enriched liquid to a liquid oxygen-argon mixture in said nitrogen rejection column, and distilling said liquid oxygen-argon mixture to said low pressure liquid oxygen in said at least one additional column.
- 6. The process according to claim 5 further comprising providing two columns for separating argon from oxygen, supplying part of said oxygen-argon mixture to each, reboiling one argon separation column by latent heat exchange with HP rectifier overhead gas and the other by latent heat exchange with partially condensing high pressure air, and obtaining said low pressure liquid oxygen from the bottom products of the two argon separation columns.
- 7. The process according to claim 6 comprising operating one argon separation column at about 1 ATA, operating the other at about 1.5 ATA, and producing oxygen of at least 99.5% purity.
- 8. In a process for producing pressurized gaseous oxygen comprising:
- (a) supplying a major fraction of air at a high pressure and the remainder at an elevated pressure;
- (b) gasifying pressurized liquid oxygen by indirect heat exchange against condensing elevated pressure air;
- (c) supplying the high pressure air plus the liquid from step (b) to a subambient distillation process;
- (d) pumping liquid oxygen obtained from the subambient distillation process to the pressure required in step (b); the improvement comprising:
- (i) providing an elevated pressure rectification column;
- (ii) refluxing the elevated pressure rectifier by indirect heat exchange with said boiling pressurized liquid oxygen;
- (iii) withdrawing as product the resulting gaseous oxygen at a pressure up to about 10 ATA while precluding the requirement of mechanical compressing of the gaseous oxygen to that pressure;
- (iv) supplying said elevated pressure air to said elevated pressure column, whereby liquid nitrogen and oxygen enriched liquid are obtained;
- (v) using said liquid nitrogen as reflux in and further separating said oxygen enriched liquid in said subambient distillation process.
- 9. The process according to claim 8 further comprising providing for the subambient distillation an HP rectifier, MP column, and LP column; reboiling both the MP and LP columns by indirect heat exchange with condensing HP rectifier overhead; refluxing both the MP and LP columns with condensed HP rectifier overhead; routing HP rectifier bottom product to the MP column for further enrichment; and routing the MP column bottom liquid to the LP column for final separation.
- 10. An apparatus for producing pressurized gaseous oxygen comprising:
- (a) a means designed for providing split supply pressure air, one fraction at a high pressure, and the remaining fraction at an elevated pressure which is at least 2 ATA higher than said high pressure;
- (b) an elevated pressure rectifier which rectifies the elevated pressure air fraction to liquid N.sub.2 and oxygen enriched liquid;
- (c) a means for pressurizing liquid oxygen;
- (d) a reflux condenser for the elevated pressure rectifier which gasifies the pressurized liquid oxygen;
- (e) a cryogenic distillation apparatus which is supplied the high pressure air fraction and the liquid N.sub.2 and oxygen enriched liquid from the elevated pressure rectifier and which produces the liquid oxygen which is pressurized in the means for pressurization;
- (f) a means designed for withdrawing said gasified pressurized liquid oxygen at a product pressure of up to about 10 ATA, said means including means for precluding a mechanical gaseous oxygen compressor.
- 11. Apparatus according to claim 10 wherein the pressurized oxygen pressure is between 2 and 10 ATA, the high pressure is between 3 and 6 ATA, and the elevated pressure is at least 21/2 times the pressurized oxygen pressure.
- 12. Apparatus according to claim 11 wherein the cryogenic distillation apparatus is comprised of a high pressure rectifier which receives said supply fluids, a nitrogen rejection column which is reboiled by latent heat exchange with the HP rectifier, and at least one column which separates argon from oxygen and supplies liquid oxygen to said means for pressurizing.
- 13. Apparatus according to claim 12 comprising two columns for separating argon from oxygen and means for dividing the liquid bottom product from the nitrogen rejection column into supply for both argon separating columns.
- 14. Apparatus according to claim 13 comprising means for reboiling one of said argon separating columns by latent heat exchange with HP rectifier overhead vapor; means for reboiling another argon separating column by latent heat exchange with partially condensing high pressure air, and means for refluxing the latter argon separation column by latent heat exchange of its overhead vapor with bottom liquid of the former argon separation column.
- 15. Apparatus according to claim 14 wherein the HP rectifier pressure is about 4.2 ATA, the N.sub.2 rejection column pressure is about 1.3 ATA, the two argon separation columns are at about 0.9 ATA and 1.5 ATA respectively.
Parent Case Info
This is a continuation-in-part of Ser. No. 416,980, filed Sept. 13, 1982 now U.S. Pat. No. 4,433,989.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
2280383 |
DeBaufre |
Apr 1942 |
|
4433989 |
Erickson |
Feb 1984 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
416980 |
Sep 1982 |
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