US4761167A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrocarbon recovery from fuel gas
Assignee: Air Products and Chemicals Inc
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Filing: 1986-12-12
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Granted: 1988-08-02
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Expires: 2006-12-12
Abstract
Abstract High purity methane is recovered from a fuel gas stream containing the same in admixture with mainly nitrogen and carbon dioxide, by first removing the carbon dioxide by selective adsorption in a PSA system and separating the remaining nitrogen from the methane by cryogenic distillation, the rejected nitrogen being employed for purging the CO 2 -laden adsorbent beds of the PSA system. Cyclic regeneration of the sorbent-laden bed may entail nitrogen purge with or without including a carbon dioxide rinse, or the nitrogen purge of the sorbent-laden bed may be used in combination with pressure let-down by gas withdrawal into one or more companion beds.
Inventors
- 👤 David M. Nicholas
- 👤 Thomas M. Roden
- 👤 Gerry N. Gottier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:56
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/02; F25J3/0228; F25J3/0257; B; B01; B01D; B01D53/00; B01D53/02; B01D53/04; B01D53/047; C; C07; C07C; C07C7/00; C07C7/12; F25J3/0204; F25J3/0219; F25J3/0233; B01D2253/00; B01D2253/10; B01D2253/106; B01D2253/108; B01D2256/00; B01D2256/10; B01D2256/24; B01D2256/245; B01D2257/00; B01D2257/50; B01D2257/504; B01D2259/00; B01D2259/40; B01D2259/40001; B01D2259/40011; B01D2259/40013; B01D2259/40015; B01D2259/40028; B01D2259/4003; B01D2259/40035; B01D2259/40037; B01D2259/40043; B01D2259/4005; B01D2259/40052; B01D2259/40058; B01D2259/40062; B01D2259/40064; B01D2259/40069; B01D2259/404; B01D2259/406; B01D2259/4061; B01D2259/416; F25J2205/00; F25J2205/40; F25J2205/60; F25J2210/00; F25J2210/12; F25J2220/00; F25J2220/60; F25J2220/64; F25J2220/66; Y; Y02; Y02C; Y02C20/00; Y02C20/40; Y02P; Y02P20/00; Y02P20/151; Y10; Y10S; Y10S62/00; Y10S62/902; Y10S62/908; Y10S62/927
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
200 words
The method of recovering methane from a fuel gas mixture containing also nitrogen and carbon dioxide, which comprises the steps of: (a) passing said fuel gas mixture at superatmospheric pressure through a bed of adsorbent wherein carbon dioxide is selectively adsorbed while withdrawing from said bed a stream comprised of unadsorbed components including methane and nitrogen; (b) subjecting said stream to cryogenic distillation to separate substantially all of the nitrogen therefrom and recovering as product methane of high purity; (c) rinsing said bed of step (a) with a stream of carbon dioxide passed through the bed in a direction co-current to that employed in initial introduction of said fuel gas mixture in step (a); (d) recycling at least a part of the effluent obtained during said rinse of step (c) as a component of the feed gas mixture subjected to step (a); (e) reducing the pressure in the bed of step (a); (f) utilizing at least part of the nitrogen separated in step (b) above to purge from the bed carbon dioxide retained therein during step (a); and (g) repressurizing said bed of step (a) with a stream of unadsorbed components having the composition of that withdrawn during step (a).
Claim 2
Independent Claim
200 words
The method of recovering methane from a fuel gas mixture containing also nitrogen and carbon dioxide, which comprises the steps of: (a) passing said fuel gas mixture at superatmospheric pressure through a bed of adsorbent wherein carbon dioxide is selectively adsorbed while withdrawing from said bed a stream comprised of unadsorbed components including methane and nitrogen; (b) subjecting said stream to cryogenic distillation to separate substantially all of the nitrogen therefrom and recovering as product methane of high purity; (c) rinsing said bed of step (a) with a stream of carbon dioxide passed through the bed in a direction co-current to that employed in initial introduction of said fuel gas mixture in step (a); (d) recycling at least a part of the effluent obtained during said rinse of step (c) as a component of the feed gas mixture subjected to step (a); (e) reducing the pressure in the bed of step (a); (f) utilizing at least part of the nitrogen separated in step (b) above to purge from the bed carbon dioxide retained therein during step (a); and (g) repressurizing said bed of step (a) with a stream of unadsorbed components having the composition of that withdrawn during step (a).
Claim 3
Dependent Claim
23 words
The method as defined in claim 1 wherein the carbon dioxide evolved from said bed during said pressure reduction is collected and recompressed.
Claim 4
Dependent Claim
83 words
The method as defined in claim 1 wherein said bed of adsorbent is part of a pressure swing adsorption system comprised of five such beds operated in parallel in a fixed time sequence, wherein each of said beds in turn is subjected to the sequence of steps: (1) adsorption of carbon dioxide, (2) rinse with carbon dioxide, (3) pressure reduction, (4) purge with nitrogen and (5) repressuring to adsorption pressure level; each of said steps being performed for a substantially equal time period.
Claim 5
Dependent Claim
27 words
The method as defined in claim 1 wherein said fuel gas mixture subjected to selective removal of carbon dioxide is one obtained from enhanced oil recovery operations.
Claim 6
Dependent Claim
48 words
The method as defined in claim 1 wherein the recited sequence of steps is carried out in a pressure swing adsorption system comprised of four adsorbent beds operated in parallel during a fixed time period cycle, wherein each of the recited steps occupies a substantially equal time period.
Claim 7
Dependent Claim
17 words
The method as defined in claim 1 wherein said adsorbent bed is comprised of 13X molecular sieve.
Claim 8
Dependent Claim
83 words
The method as defined in claim 1 wherein said bed of adsorbent is part of a pressure swing adsorbent system comprised of at least five such beds operated in parallel in a fixed time sequence, and wherein following recited step (a) the pressure in the carbon dioxide-laden bed is lowered by passing gas therefrom into one or more companion beds which are at lower pressure level, followed by further removal of gas passed therefrom into a holding receptacle, prior to purging with nitrogen.
Claim 9
Dependent Claim
42 words
The method as defined in claim 7 wherein following its purging with nitrogen the bed is brought to the superatmospheric pressure level of step (a) with unadsorbed gas withdrawn from a companion bed during the adsorptioin step performed in said companion bed.
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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) | 1991-08-02 | 1992-02-01 | 1992-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-02 | 1996-02-01 | 1996-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-02 | 2000-02-01 | 2000-08-02 | $7700.00 | Window Closed / Lapsed |