Patent US4848996A successfully refreshed from Google Patents.
US4848996A
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Nitrogen generator with waste distillation and recycle of waste distillation overhead
Assignee: Air Products and Chemicals Inc
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Filing: 1988-10-06
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Granted: 1989-07-18
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Expires: 2008-10-06
Abstract
Abstract The present invention is an improvement to a standard nitrogen generator. The improvement is two-fold; first, the addition of one or more distillation stages above the reboiler, which stages effectively transform the reboiler/condenser into a partial low pressure column and allow further separation (rectification) of the nitrogen generator bottoms liquid into two streams. Second, the recycle of the overhead stream (at a composition close to that of air) from the top of the low pressure column to the main air compressor. Additionally, at least a portion of the oxygen-enriched stream that exits the low pressure column below the bottom tray is expanded to provide refrigeration for the cycle.
Inventors
- 👤 Robert M. Thorogood
- 👤 Thomas M. Roden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:46
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/02; F25J3/04; F25J3/04248; F25J3/04284; F25J3/04321; F25J3/04406; F25J3/0443; F25J3/04763; F25J3/04866; F25J3/04969; F25J2210/00; F25J2210/04; F25J2215/00; F25J2215/42; F25J2215/44; F25J2230/00; F25J2230/40; F25J2245/00; F25J2245/02
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
211 words
In a process for the separation of air by cryogenic distillation wherein a feed air stream is compressed by a multi-staged main air compressor, cooled to near the dew point of the feed air stream and separated into a nitrogen overhead stream and an oxygen-enriched bottoms liquid in a stripper; at least a portion of the nitrogen overhead is condensed in a reboiler/condenser to provide reflux for the stripper; and at least another portion of the nitrogen overhead is removed from the process as gaseous nitrogen product; the improvement for producing gaseous nitrogen product in a more energy efficient manner comprises: (a) rectifying the oxygen-enriched bottoms liquid in a distillation zone comprising one or more distillation stages into a synthetic air recycle stream and an oxygen-enriched waste stream; (b) warming the synthetic air recycle stream to recover refrigeration and subsequently recycling the warmed synthetic air recycle stream to an intermediate stage of the multi-staged main air compressor; (c) reboiling at least a portion of the oxygen-enriched waste stream in the reboiler/condenser thereby condensing at least a portion of the nitrogen overhead from the stripper and producing a gaseous oxygen-enriched stream; and (d) expanding and subsequently warming at least a portion of the gaseous oxygen-enriched stream to provide refrigeration for the process.
Claim 2
Dependent Claim
211 words
In a process for the separation of air by cryogenic distillation wherein a feed air stream is compressed by a multi-staged main air compressor, cooled to near the dew point of the feed air stream and separated into a nitrogen overhead stream and an oxygen-enriched bottoms liquid in a stripper; at least a portion of the nitrogen overhead is condensed in a reboiler/condenser to provide reflux for the stripper; and at least another portion of the nitrogen overhead is removed from the process as gaseous nitrogen product; the improvement for producing gaseous nitrogen product in a more energy efficient manner comprises: (a) rectifying the oxygen-enriched bottoms liquid in a distillation zone comprising one or more distillation stages into a synthetic air recycle stream and an oxygen-enriched waste stream; (b) warming the synthetic air recycle stream to recover refrigeration and subsequently recycling the warmed synthetic air recycle stream to an intermediate stage of the multi-staged main air compressor; (c) reboiling at least a portion of the oxygen-enriched waste stream in the reboiler/condenser thereby condensing at least a portion of the nitrogen overhead from the stripper and producing a gaseous oxygen-enriched stream; and (d) expanding and subsequently warming at least a portion of the gaseous oxygen-enriched stream to provide refrigeration for the process.
Claim 3
Dependent Claim
15 words
The process of claim 1, wherein the distillation zone comprises three or more distillation trays.
Claim 4
Dependent Claim
219 words
In a process for the separation of a feed gas stream comprising oxygen and nitrogen by cryogenic distillation wherein the feed gas stream is compressed by a multi-staged main compressor, cooled to near the dew point of the feed gas stream and separated into a nitrogen overhead stream and an oxygen-enriched bottoms liquid in a stripper; at least a portion of the nitrogen overhead is condensed in a reboiler/condenser to provide reflux for the stripper; and at least another portion of the nitrogen overhead is removed from the process as gaseous nitrogen product; the improvement for producing gaseous nitrogen product in a more energy efficient manner comprises: (a) rectifying the oxygen-enriched bottoms liquid in a distillation zone comprising one or more distillation stages into a synthetic feed gas recycle stream and an oxygen-enriched waste stream; (b) warming the synthetic feed gas recycle stream to recover refrigeration and subsequently recycling the warmed synthetic feed gas recycle stream to an intermediate stage of the multi-staged main compressor; (c) reboiling at least a portion of the oxygen-enriched waste stream in the reboiler/condenser thereby condensing at least a portion of the nitrogen overhead from the stripper and producing a gaseous oxygen-enriched stream; and (d) expanding and subsequently warming at least a portion of the gaseous oxygen-enriched stream to provide refrigeration for the process.
Claim 5
Dependent Claim
219 words
In a process for the separation of a feed gas stream comprising oxygen and nitrogen by cryogenic distillation wherein the feed gas stream is compressed by a multi-staged main compressor, cooled to near the dew point of the feed gas stream and separated into a nitrogen overhead stream and an oxygen-enriched bottoms liquid in a stripper; at least a portion of the nitrogen overhead is condensed in a reboiler/condenser to provide reflux for the stripper; and at least another portion of the nitrogen overhead is removed from the process as gaseous nitrogen product; the improvement for producing gaseous nitrogen product in a more energy efficient manner comprises: (a) rectifying the oxygen-enriched bottoms liquid in a distillation zone comprising one or more distillation stages into a synthetic feed gas recycle stream and an oxygen-enriched waste stream; (b) warming the synthetic feed gas recycle stream to recover refrigeration and subsequently recycling the warmed synthetic feed gas recycle stream to an intermediate stage of the multi-staged main compressor; (c) reboiling at least a portion of the oxygen-enriched waste stream in the reboiler/condenser thereby condensing at least a portion of the nitrogen overhead from the stripper and producing a gaseous oxygen-enriched stream; and (d) expanding and subsequently warming at least a portion of the gaseous oxygen-enriched stream to provide refrigeration for the process.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-17 | 1993-01-16 | 1993-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-17 | 1997-01-16 | 1997-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-17 | 2001-01-16 | 2001-07-18 | $7700.00 | Window Closed / Lapsed |