US4409102A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for removing contaminants from a stream of methane gas
Assignee: CENTRAL PLANTS Inc A CORP OF CA
•
Filing: 1981-11-27
•
Granted: 1983-10-11
•
Expires: 2001-11-27
Abstract
Abstract A feed stream of digester gas from an anaerobic process is compressed to a predetermined pressure of about 300 p.s.i.g. and fed into an absorber at that pressure. Carbon dioxide and hydrogen sulfide impurities of this feed stream are absorbed in the absorber by counterflowing water. Water from the absorber may be fed back to an activated sludge sewage treatment facility where the hydrogen sulfide is oxidized and the carbon dioxide released. As an alternative to the absorber, hydrogen sulfide is oxidized in an iron sponge reaction. Alternately, these contaminants are stripped with air and vented. Treated gas from the absorber, essentially methane, is either compressed for introduction into storage tanks, or dried and used as pipeline gas. In the dryer, adsorbed moisture is removed by air, followed by a purge with treated gas.
Inventors
- 👤 Milton R. Tanner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:06
CPC Classifications
C; C12; C12M; C12M47/00; C12M47/18; B; B01; B01D; B01D53/00; B01D53/14; B01D53/1456; B01D53/1462; C02; C02F; C02F1/00; C02F1/20; C02F1/72; C02F3/00; C02F3/30; C07; C07C; C07C7/00; C07C7/11; C12M21/00; C12M21/04; Y; Y02; Y02C; Y02C20/00; Y02C20/40; Y02E; Y02E50/00; Y02E50/30; Y02P; Y02P20/00; Y02P20/151; Y02P20/50; Y02P20/59; Y02W; Y02W10/00; Y02W10/10
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
124 words
A process for removing contaminants of hydrogen sulfide and carbon dioxide from a low pressure, methane containing feed stream from an anaerobic process comprising: (a) compressing the feed stream to an intermediate pressure; (b) removing substantially all the hydrogen sulfide from the feed stream at the intermediate pressure; (c) compressing the feed stream after the hydrogen sulfide removal step to an absorption pressure that is greater than the intermediate pressure; (d) absorbing substantially all the carbon dioxide in the stream at the absorption pressure in water in an absorber to produce a treated gas stream; (e) stripping the carbon dioxide from the water at a pressure lower than the absorption pressure; and (f) recycling the water into the absorber to absorb further carbon dioxide.
Claim 2
Dependent Claim
124 words
A process for removing contaminants of hydrogen sulfide and carbon dioxide from a low pressure, methane containing feed stream from an anaerobic process comprising: (a) compressing the feed stream to an intermediate pressure; (b) removing substantially all the hydrogen sulfide from the feed stream at the intermediate pressure; (c) compressing the feed stream after the hydrogen sulfide removal step to an absorption pressure that is greater than the intermediate pressure; (d) absorbing substantially all the carbon dioxide in the stream at the absorption pressure in water in an absorber to produce a treated gas stream; (e) stripping the carbon dioxide from the water at a pressure lower than the absorption pressure; and (f) recycling the water into the absorber to absorb further carbon dioxide.
Claim 3
Dependent Claim
25 words
The process claimed in claim 1 including the step of compressing the treated gas stream to a pressure adequate to charge high pressure storage tanks.
Claim 4
Dependent Claim
21 words
The process claimed in claim 1 including the step of drying the treated gas stream to remove substantially all the moisture.
Claim 5
Dependent Claim
13 words
The process claimed in claim 3 wherein the drying step is by adsorption.
Claim 6
Dependent Claim
48 words
The process claimed in claim 4 wherein adsorption is effected in at least two air dryer adsorbers, and including the steps of periodically taking each adsorber off line while the other adsorber remains on line and removing the moisture from the off line adsorber by evaporation to atmosphere.
Claim 7
Dependent Claim
37 words
The process claimed in claim 1 wherein the compression step is effected in a compressor of at least two stages, and the hydrogen sulfide is removed by oxidizing it in an iron sponge reaction between compression stages.
Claim 8
Dependent Claim
52 words
The process claimed in claim 6 wherein the treated gas stream is substantially dried in at least two air dryer adsorbers, and including the steps of periodically taking each adsorber off line while the other adsorber remains on line and removing the moisture from the off line adsorber by evaporation to atmosphere.
Claim 9
Dependent Claim
111 words
A process for removing carbon dioxide and hydrogen sulfide from a feed stream containing them and methane comprising the steps of: (a) forming the feed stream containing hydrogen sulfide, carbon dioxide, and methane from an anaerobic process; (b) compressing the feed stream to an absorption pressure in a compressor of at least two stages; (c) removing the hydrogen sulfide from the feed stream by oxidation in an iron sponge reaction between compression stages and at a pressure less than the pressure after the second compression stage; and (d) absorbing the carbon dioxide in the feed stream at the absorption pressure in water to produce a treated gas stream of primarily methane.
Claim 10
Dependent Claim
111 words
A process for removing carbon dioxide and hydrogen sulfide from a feed stream containing them and methane comprising the steps of: (a) forming the feed stream containing hydrogen sulfide, carbon dioxide, and methane from an anaerobic process; (b) compressing the feed stream to an absorption pressure in a compressor of at least two stages; (c) removing the hydrogen sulfide from the feed stream by oxidation in an iron sponge reaction between compression stages and at a pressure less than the pressure after the second compression stage; and (d) absorbing the carbon dioxide in the feed stream at the absorption pressure in water to produce a treated gas stream of primarily methane.
Claim 11
Dependent Claim
15 words
The process claimed in claim 8 including the step of compressing the treated gas stream.
Claim 12
Dependent Claim
20 words
The process claimed in claim 8 including the step of removing substantially all the water from the treated gas stream.
Claim 13
Dependent Claim
50 words
The process claimed in claim 10 wherein the removal step is by adsorption in at least two air dryer adsorbers, and including the steps of periodically and sequentially diverting the treated gas stream from each of the adsorbers and removing the water from the diverted adsorber by evaporation to atmosphere.
Claim 14
Dependent Claim
144 words
A process for purifying a feed gas stream of methane, hydrogen sulfide and carbon dioxide by removal of the hydrogen sulfide and carbon dioxide, comprising the steps of: (a) compressing the feed gas stream to an intermediate pressure; (b) removing a substantial portion of the hydrogen sulfide from the feed gas stream at the intermediate pressure; (c) compressing the feed gas stream after the hydrogen sulfide removal step to an absorption pressure that is greater than the intermediate pressure; (d) absorbing the carbon dioxide from the feed gas stream in an absorber at the absorber pressure in water from a water treatment facility to obtain a treated gas stream; (e) passing the water with the absorbed hydrogen sulfide and carbon dioxide to the water treatment facility; and (f) compressing the treated gas stream to a pressure suitable for introduction into high pressure storage tanks.
Claim 15
Dependent Claim
144 words
A process for purifying a feed gas stream of methane, hydrogen sulfide and carbon dioxide by removal of the hydrogen sulfide and carbon dioxide, comprising the steps of: (a) compressing the feed gas stream to an intermediate pressure; (b) removing a substantial portion of the hydrogen sulfide from the feed gas stream at the intermediate pressure; (c) compressing the feed gas stream after the hydrogen sulfide removal step to an absorption pressure that is greater than the intermediate pressure; (d) absorbing the carbon dioxide from the feed gas stream in an absorber at the absorber pressure in water from a water treatment facility to obtain a treated gas stream; (e) passing the water with the absorbed hydrogen sulfide and carbon dioxide to the water treatment facility; and (f) compressing the treated gas stream to a pressure suitable for introduction into high pressure storage tanks.
Claim 16
Dependent Claim
20 words
The process claimed in claim 12 including the step of removing substantially all the moisture from the treated gas stream.
Claim 17
Dependent Claim
39 words
The process claimed in claim 13 wherein the moisture is removed in at least two air dryer adsorbers, and including the steps of periodically and sequentially taking each adsorber off line and removing its moisture by evaporation into air.
References Cited (Backward Citations)
US1907579A
Cited
US2033933A
Cited
US2097454A
Cited
US2208029A
Cited
US2378689A
Cited
US2541630A
Cited
US2780310A
Cited
US2881137A
Cited
US2983573A
Cited
US3847570A
Cited
US3981800A
Cited
US4000990A
Cited
US3973043A
Cited
US4123355A
Cited
US4157958A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-10 | 1987-04-11 | 1987-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-10 | 1991-04-11 | 1991-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-10 | 1995-04-11 | 1995-10-11 | $7700.00 | Window Closed / Lapsed |