US4352685A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for removing nitrogen from natural gas
Assignee: Union Carbide Industrial Gases Technology Corp
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Filing: 1981-06-24
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Granted: 1982-10-05
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Expires: 2001-06-24
Abstract
Abstract A process which effectively removes nitrogen from natural gas over a wide range of nitrogen concentrations and wherein the natural gas may also contain high concentrations of heavy hydrocarbons. The process is especially advantageous for the purification of a natural gas stream recovered from a petroleum field where nitrogen injection is employed as an enhanced recovery technique.
Inventors
- 👤 Brian R. Swallow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:50
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/02; F25J3/0228; F25J3/0257; C; C07; C07C; C07C7/00; C07C7/04; F25J3/0204; F25J3/0209; F25J3/0233; F25J3/0242; F25J2200/00; F25J2200/04; F25J2200/08; F25J2200/38; F25J2200/74; F25J2205/00; F25J2205/02; F25J2270/00; F25J2270/90; F25J2290/00; F25J2290/40; Y; Y10; Y10S; Y10S62/00; Y10S62/927
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
237 words
A process for separating nitrogen from natural gas comprising: (1) introducing an at least partially condensed nitrogen-containing natural gas feed stream which is essentially free of water and carbon dioxide and is at a pressure of at least 400 psia, to a first stripping column wherein the stream is separated by rectification into a nitrogen-methane gas stream A and a heavy hydrocarbon-methane liquid stream B; (2) partially condensing stream A to produce a nitrogen-methane gas stream C and a liquid stream D; (3) introducing stream D to said first stripping column; (4) introducing stream C to a nitrogen-methane separation zone wherein the stream is separated into a nitrogen stream E and a methane stream F; (5) partially vaporizing stream B to produce a gas stream G and a heavy hydrocarbon-enriched liquid stream H; (6) introducing stream G to said first stripping column as vapor reflux; (7) introducing stream H to a second stripping column wherein it is separated by rectification into a methane-rich stream I and a liquid stream J; (8) partially condensing stream I to produce a methane gas stream K and a liquid stream L; (9) introducing stream L to said second stripping column; (10) partially vaporizing stream J to produce a gas stream M and a heavy hydrocarbon liquid stream N; (11) introducing stream M to said second stripping column as vapor reflux; and (12) recovering stream F and stream K as product methane.
Claim 2
Dependent Claim
237 words
A process for separating nitrogen from natural gas comprising: (1) introducing an at least partially condensed nitrogen-containing natural gas feed stream which is essentially free of water and carbon dioxide and is at a pressure of at least 400 psia, to a first stripping column wherein the stream is separated by rectification into a nitrogen-methane gas stream A and a heavy hydrocarbon-methane liquid stream B; (2) partially condensing stream A to produce a nitrogen-methane gas stream C and a liquid stream D; (3) introducing stream D to said first stripping column; (4) introducing stream C to a nitrogen-methane separation zone wherein the stream is separated into a nitrogen stream E and a methane stream F; (5) partially vaporizing stream B to produce a gas stream G and a heavy hydrocarbon-enriched liquid stream H; (6) introducing stream G to said first stripping column as vapor reflux; (7) introducing stream H to a second stripping column wherein it is separated by rectification into a methane-rich stream I and a liquid stream J; (8) partially condensing stream I to produce a methane gas stream K and a liquid stream L; (9) introducing stream L to said second stripping column; (10) partially vaporizing stream J to produce a gas stream M and a heavy hydrocarbon liquid stream N; (11) introducing stream M to said second stripping column as vapor reflux; and (12) recovering stream F and stream K as product methane.
Claim 3
Dependent Claim
22 words
The process of claim 1 wherein streams F and K are combined into one stream before they are recovered as product methane.
Claim 4
Dependent Claim
18 words
The process of claim 1 wherein heavy hydrocarbon liquid stream N is recovered as product liquid petroleum gas.
Claim 5
Dependent Claim
13 words
The process of claim 1 wherein stream E is released to the atmosphere.
Claim 6
Dependent Claim
13 words
The process of claim 1 wherein stream E is recovered as product nitrogen.
Claim 7
Dependent Claim
21 words
The process of claim 1 wherein stream A is partially condensed by countercurrent heat exchange with stream E and/or stream F.
Claim 8
Dependent Claim
22 words
The process of claim 1 wherein stream B is partially vaporized by countercurrent heat exchange with the nitrogen-containing natural gas feed stream.
Claim 9
Dependent Claim
21 words
The process of claim 1 wherein stream I is partially condensed by countercurrent heat exchange with stream E and/or stream F.
Claim 10
Dependent Claim
22 words
The process of claim 1 wherein stream J is partially vaporized by countercurrent heat exchange with the nitrogen-containing natural gas feed stream.
Claim 11
Dependent Claim
15 words
The process of claim 1 wherein said nitrogen-methane separation zone is a double distillation column.
Claim 12
Dependent Claim
24 words
The process of claim 1 wherein the concentration of nitrogen in the nitrogen-containing natural gas feed stream is from about 15 to 60 percent.
Claim 13
Dependent Claim
33 words
The process of claim 1 wherein the nitrogen-containing natural gas feed stream additionally contains heavy hydrocarbons in a concentration such that the mole ratio of heavy hydrocarbon to methane is greater than 0.1.
Claim 14
Dependent Claim
27 words
The process of claim 1 wherein the concentration of nitrogen in stream C immediately before its introduction to the nitrogen-methane separation zone is at least 20 percent.
Claim 15
Dependent Claim
21 words
The process of claim 1 wherein the nitrogen-containing natural gas feed stream is at a pressure of at least 600 psia.
Claim 16
Dependent Claim
44 words
The process of claim 1 wherein the pressure of the nitrogen-containing natural gas feed stream is initially at or above its critical pressure and said pressure is reduced to below the critical pressure before the feed stream is introduced to the first stripping column.
Claim 17
Dependent Claim
13 words
The process of claim 15 wherein said pressure is 1000 psia or more.
Claim 18
Dependent Claim
23 words
The process of claim 1 wherein the pressure in the second stripping column is less than the pressure in the first stripping column.
Claim 19
Dependent Claim
21 words
The process of claim 1 wherein the pressure in the second stripping column is from about 300 to about 400 psia.
References Cited (Backward Citations)
US3271099A
Cited
US3874184A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-04 | 1986-04-05 | 1986-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-04 | 1990-04-05 | 1990-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-04 | 1994-04-05 | 1994-10-05 | $7700.00 | Window Closed / Lapsed |