US4750925A
Expired / Lapsed
US
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Argon recovery from hydrogen depleted ammonia plant purge gas utilizing a combination of cryogenic and non-cryogenic separating means
Assignee: Messer LLC
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Filing: 1987-05-04
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Granted: 1988-06-14
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Expires: 2007-05-04
Abstract
Abstract An improved process is provided for the recovery of argon from a gas mixture comprising hydrogen, nitrogen, methane and argon. An example of such a gas mixture is purge gas from an ammonia synthesis plant which has been subjected to the conventional steps of ammonia absorption and a membrane separation to obtain hydrogen for recycle to the ammonia plant. In a first embodiment, the gas mixture is treated in a pressure swing adsorption (PSA) system to remove the methane, residual moisture and most of the hydrogen, the resulting gas mixture is treated in a membrane separator to remove most of the hydrogen, which may be used as purge gas for the PSA system, and the resulting stream treat by cryogenic distillation to separate the nitrogen and residual hydrogen to obtain an essentially pure argon product. In a second embodient, the second treatment is eliminated and all of the hydrogen is removed by the cryogenic distillation. In a third embodiment, metal hydride adsorption is used in place of the membrane to separate the hydrogen. The process is enhanced by the recycle of vent gas from the PSA unit to the process itself or to the ammonia synthesis plant. Alternatively, a cocurrent depressurization product from the PSA plant can be recycled into the process.
Inventors
- 👤 Donald L. MacLean
- 👤 Ramachandran Krishnamurthy
- 👤 Steven L. Lerner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:41
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/02; F25J3/0228; F25J3/0252; B; B01; B01D; B01D53/00; B01D53/02; B01D53/04; B01D53/047; B01D53/22; B01D53/229; C; C01; C01B; C01B23/00; C01C; C01C1/00; C01C1/02; C01C1/04; C01C1/0405; C01C1/0476; F25J3/0204; F25J3/0219; F25J3/028; F25J3/0285; B01D2253/00; B01D2253/10; B01D2253/102; B01D2253/106; B01D2253/108; B01D2253/112; B01D2253/1126; B01D2256/00; B01D2256/16; B01D2257/00; B01D2257/10; B01D2257/102; B01D2257/108; B01D2257/40; B01D2257/406; B01D2257/70; B01D2257/702; B01D2257/7022; B01D2257/7025; B01D2257/80; B01D2259/00; B01D2259/40; B01D2259/40001; B01D2259/40011; B01D2259/40013; B01D2259/40016; B01D2259/40028; B01D2259/4003; B01D2259/40032; B01D2259/40035; B01D2259/40037; B01D2259/40043; B01D2259/4005; B01D2259/40052; B01D2259/40058; B01D2259/40071; B01D2259/402; B01D2259/414; B01D2259/4141; B01D2259/4143; B01D2259/4145; B01D2259/4146; B01D2259/416; B01D53/0476; F25J2205/00; F25J2205/40; F25J2205/60; F25J2205/80; F25J2210/00; F25J2210/20; Y; Y02; Y02C; Y02C20/00; Y02C20/20; Y02P; Y02P20/00; Y02P20/10; Y02P20/129; Y02P20/151; Y02P20/156; Y02P20/50; Y02P20/52; Y10; Y10S; Y10S62/00; Y10S62/902; Y10S62/908
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
150 words
A process for the recovery of argon from a gas stream comprising hydrogen, nitrogen, methane, and argon comprising (i) passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream containing an increased amount of argon; (ii) passing said product stream to a means for separating out most of the hydrogen, thereby producing a hydrogen depleted product stream; and (iii) passing said hydrogen depleted product stream to a cryogenic distillation means for separating the remaining nitrogen and hydrogen, thereby producing an essentially pure argon final product, the process further comprising recycling all or part of the vent gas from the pressure swing adsorption means into the process or, in the event said gas mixture is the purge gas from an ammonia synthesis plant which has been treated to remove ammonia therefrom, to said plant.
Claim 2
Dependent Claim
150 words
A process for the recovery of argon from a gas stream comprising hydrogen, nitrogen, methane, and argon comprising (i) passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream containing an increased amount of argon; (ii) passing said product stream to a means for separating out most of the hydrogen, thereby producing a hydrogen depleted product stream; and (iii) passing said hydrogen depleted product stream to a cryogenic distillation means for separating the remaining nitrogen and hydrogen, thereby producing an essentially pure argon final product, the process further comprising recycling all or part of the vent gas from the pressure swing adsorption means into the process or, in the event said gas mixture is the purge gas from an ammonia synthesis plant which has been treated to remove ammonia therefrom, to said plant.
Claim 3
Dependent Claim
25 words
The process of claim 1 wherein said vent gas is recycled into the process to the pressure swing adsorption means via the feed stream thereto.
Claim 4
Dependent Claim
36 words
The process of claim 2, wherein the vent gas is collected in two fractions, the first fraction is recycled to the pressure swing adsorption means and the second fraction is used for fuel in said process.
Claim 5
Dependent Claim
24 words
The process of claim 1, wherein the ammonia synthesis plant includes a secondary reformer and said vent gas is recycled to said secondary reformer.
Claim 6
Dependent Claim
34 words
The process of claim 4, wherein the vent gas is collected in two fractions, the first fraction is recycled to the secondary reformer and the second fraction is used for fuel in said plant.
Claim 7
Dependent Claim
120 words
A process for the recovery of argon from a gas stream comprising hydrogen, nitrogen, methane, and argon comprising (i) passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream containing an increased amount of argon; (ii) passing said product stream to a means for separating out most of the hydrogen, thereby producing a hydrogen depleted product stream; and (iii) passing said hydrogen depleted product stream to a cryogenic distillation means for separating the remaining nitrogen and hydrogen, thereby producing an essentially pure argon final product, the process further comprising recycling into said process a cocurrent depressurization product from the pressure swing adsorption means.
Claim 8
Dependent Claim
120 words
A process for the recovery of argon from a gas stream comprising hydrogen, nitrogen, methane, and argon comprising (i) passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream containing an increased amount of argon; (ii) passing said product stream to a means for separating out most of the hydrogen, thereby producing a hydrogen depleted product stream; and (iii) passing said hydrogen depleted product stream to a cryogenic distillation means for separating the remaining nitrogen and hydrogen, thereby producing an essentially pure argon final product, the process further comprising recycling into said process a cocurrent depressurization product from the pressure swing adsorption means.
Claim 9
Dependent Claim
17 words
The process of claims 1 or 6, wherein said means for separating hydrogen is a membrane separator.
Claim 10
Dependent Claim
26 words
The process of claims 1 or 6, wherein one or more equalization tanks are connected to the pressure swing adsorption means to reduce void gas loss.
Claim 11
Dependent Claim
19 words
The process of claims 1 or 6, wherein a product backfill repressurization step is included to increase product purity.
Claim 12
Dependent Claim
34 words
The process of claims 1 or 6, wherein the feed gas to said pressure swing absorption is cooled by expansion from a high pressure to the operating pressure of said pressure swing adsorption means.
Claim 13
Dependent Claim
36 words
The process of claims 1 or 6, wherein refrigeration for said cryogenic distillation means is obtained by vaporizing liquid nitrogen from storage tanks and passing the nitrogen vapor to an ammonia synthesis compressor air intake section.
Claim 14
Dependent Claim
45 words
The process of claims 1 or 6, wherein the product stream from said pressure swing adsorption means is cooled by heat exchange with waste gas leaving said cryogenic distillation means and by expansion to the pressure of said cryogenic distillation means before entering the same.
Claim 15
Dependent Claim
37 words
The process of claims 1 or 6, wherein any ammonia or residual water present in the said gas stream entering the pressure swing adsorption means is discharged in the vent gas of said pressure swing adsorption means.
Claim 16
Dependent Claim
22 words
The process of claims 1 or 6, wherein the methane concentration in said product is equal to or less than 20 ppm.
Claim 17
Dependent Claim
17 words
The process of claim 14, wherein said methane concentration is less than or equal to 1 ppm.
Claim 18
Dependent Claim
24 words
The process of claims 1 or 6 wherein the operating pressure of said pressure swing adsorption means ranges from 25 psig to 1000 psig.
Claim 19
Dependent Claim
15 words
The process of claim I6, wherein the operating pressure ranges from 100 to 400 psig.
Claim 20
Dependent Claim
43 words
The process of claims 1 or 6, wherein refrigeration for said cryogenic distillation means is obtained by recirculating a refrigerant in a refrigerated heat pump cycle and using the column reboiler of said cryogenic distillation means as a heat sink for the cycle.
Claim 21
Dependent Claim
30 words
The process of claim 18, wherein pressure energy of a high pressure non-permeate gas, through the use of a turbine, is used to drive a compressor for circulating said refrigerant.
Claim 22
Dependent Claim
18 words
The process of claim 1 or 6, wherein said adsorbent material is a molecular sieve or activated carbon.
Claim 23
Dependent Claim
15 words
The process of claim 20, wherein said molecular sieve adsorbent material is an aluminosilicate zeolite.
Claim 24
Dependent Claim
20 words
The process of claim 21, wherein said zeolite is selected from the group consisting of 5A, 10X, 13X, or mordenites.
Claim 25
Dependent Claim
17 words
The process of claim 22, wherein said zeolite comprises 5A medical grade sieve or 5A HC sieve.
Claim 26
Dependent Claim
32 words
The process of claims 1 or 6, wherein said pressure swing adsorption means comprises at least one adsorption bed containing an adsorbent material which has a greater selectivity for methane than argon.
Claim 27
Dependent Claim
13 words
The process of claim 24, wherein said adsorption bed periodically undergoes vacuum regeneration.
Claim 28
Dependent Claim
16 words
The process of claim 24, wherein said adsorption bed is periodically regenerated with a purge gas.
Claim 29
Dependent Claim
22 words
The process of claim 26, wherein said purge gas is the hydrogen rich stream exiting from said means for separating out hydrogen.
Claim 30
Dependent Claim
25 words
The process of claim 26, wherein the purge gas is a hydrogen and nitrogen gaseous mixture exiting from the top of said cryogenic distillation means.
Claim 31
Dependent Claim
19 words
The process of claim 24, wherein said means for separating hydrogen is one or more beds comprising metal hydrides.
Claim 32
Dependent Claim
15 words
The process of claim 29, wherein said metal hydrides are incorporated into said adsorption bed.
Claim 33
Dependent Claim
30 words
The process of claim 30, wherein said metal hydrides forms a discrete alternate layer with said molecular sieve adsorbent material in said adsorption bed of said pressure swing adsorption means.
Claim 34
Dependent Claim
21 words
The process of claim 30, wherein a layer of hydride-zeolite mixture is placed between two zeolite layers in said adsorption bed.
Claim 35
Dependent Claim
122 words
A process for the recovery of argon from a gas stream comprising hydogen, nitrogen, methane and argon comprising passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream comprising a predominant amount of argon, and passing said product stream to a cryogenic distillation column for separating out hydrogen and nitrogen and producing an essentially pure argon product, said process further comprising recycling all or part of the vent gas from the pressure swing adsorption means into the process or, in the event said gas mixture is the purge gas from an ammonia synthesis plant which has been treated to remove ammonia therefrom, to said plant.
Claim 36
Dependent Claim
122 words
A process for the recovery of argon from a gas stream comprising hydogen, nitrogen, methane and argon comprising passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream comprising a predominant amount of argon, and passing said product stream to a cryogenic distillation column for separating out hydrogen and nitrogen and producing an essentially pure argon product, said process further comprising recycling all or part of the vent gas from the pressure swing adsorption means into the process or, in the event said gas mixture is the purge gas from an ammonia synthesis plant which has been treated to remove ammonia therefrom, to said plant.
Claim 37
Dependent Claim
92 words
A process for the recovery of argon from a gas stream comprising hydrogen, nitrogen, methane and argon comprising passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream comprising a predominant amount of argon, and passing said product stream to a cryogenic distillation column for separating out hydrogen and nitrogen and producing an essentially pure argon product, said process further comprising recycling into the process a cocurrent depressurization product from the pressure swing adsorption means.
Claim 38
Dependent Claim
92 words
A process for the recovery of argon from a gas stream comprising hydrogen, nitrogen, methane and argon comprising passing said gas stream through a pressure swing adsorption means for separating essentially all of the methane and most of the nitrogen, thereby producing a product stream comprising a predominant amount of argon, and passing said product stream to a cryogenic distillation column for separating out hydrogen and nitrogen and producing an essentially pure argon product, said process further comprising recycling into the process a cocurrent depressurization product from the pressure swing adsorption means.
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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) | 1991-06-14 | 1991-12-14 | 1992-06-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-14 | 1995-12-14 | 1996-06-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-14 | 1999-12-14 | 2000-06-14 | $7700.00 | Window Closed / Lapsed |