US3797261A
Expired / Lapsed
US
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Single-stage fractionation of natural gas containing nitrogen
Assignee: Linde GmbH
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Filing: 1971-05-11
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Granted: 1974-03-19
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Expires: 1991-05-11
Abstract
Abstract Separation of natural gas containing nitrogen into a lownitrogen fraction and a high-nitrogen fraction is achieved in a single distillation column in which reflux is provided by expanding the high-nitrogen fraction with the performance of work and using the resulting refrigeration to condense vapor in the upper section of the column while additional reflux is provided by vaporizing a recycle medium in heat exchange relation with vapor in the column. Incoming natural gas is passed in heat exchange relation with liquid in the column bottom, further cooled and expanded into the middle section of the column. A helium-rich fraction may be separated from the high-nitrogen fraction.
Inventors
- 👤 F Juncker
- 👤 J Kranz
- 👤 M Streich
- 👤 H Tanz
- 👤 G Vollrath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:12
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/02; F25J3/0228; F25J3/028; F25J3/029; C; C07; C07C; C07C7/00; C07C7/04; F25J3/0204; F25J3/0209; F25J3/0233; F25J3/0257; F25J2200/00; F25J2200/02; F25J2200/50; F25J2200/74; F25J2205/00; F25J2205/02; F25J2235/00; F25J2235/60; F25J2240/00; F25J2240/02; F25J2240/12; F25J2270/00; F25J2270/02; F25J2270/04; F25J2270/06; F25J2270/12; F25J2270/60; F25J2270/66; Y; Y10; Y10S; Y10S62/00; Y10S62/927
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
23 words
The process of claim 1 wherein the distillation zone is maintained at a pressure in the range of about 10 to 35 ata.
Claim 2
Dependent Claim
58 words
The process of claim 1 wherein the nitrogen content of the natural gas is over 20 percent by volume and the expansion of high-nitrogen fraction with the performance of work is conducted in several stages with the resulting refrigeration of each stage being used to condense vapor at different levels of the upper section of the distillation zone.
Claim 3
Dependent Claim
70 words
The process of claim 1 wherein the natural gas containing nitrogen is passed in indirect heat exchange relation with liquid at the bottom of the distillation zone, then with the expanded high-nitrogen fraction and again with liquid at an intermediate level of said distillation zone, is expanded to a pressure in the range of about 10 to 35 ata and is discharged into the middle section of said distillation zone.
Claim 4
Dependent Claim
39 words
The process of claim 1 wherein the recycle liquefied gas is methane, the nitrogen content of the natural gas is at least 40 percent by volume, and the distillation zone is maintained at a pressure of about 28 ata.
Claim 5
Dependent Claim
89 words
The process of claim 1 wherein the natural gas containing nitrogen also contains helium and a helium-rich fraction is recovered by partially condensing nitrogen in the vapor withdrawn from the top of the distillation zone in two condensation stages, for refrigeration for the first of said stages being provided by evaporating at reduced high pressure liquid withdrawn from the top of said distillation zone and the refrigeration for the second of said stages being provided by the high-nitrogen fraction expanded with the performance of work to nearly atmospheric pressure.
Claim 6
Dependent Claim
71 words
The process of claim 4 wherein the nitrogen content of the natural gas is over 20 percent by volume, the expansion of high-nitrogen fraction with the performance of work is conducted in two stages, the discharge pressure of the second of said stages being nearly atmospheric, and the resulting refrigeration of each of said stages is used to condence vapor at different levels of the upper section of the distillation zone.
Claim 7
Dependent Claim
89 words
The process of claim 7 wherein the natural gas containing nitrogen also contains helium and a helium-rich fraction is recovered by partially condensing nitrogen in the vapor withdrawn from the top of the distillation zone in two condensation stages, the refrigeration for the first of said stages being provided by evaporating at reduced high pressure liquid withdrawn fRom the top of said distillation zone and the refrigeration for the second of said stages being provided by the high-nitrogen fraction expanded with the performance of work to nearly atmospheric pressure.
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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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |