EP0183358A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Production of ammonia synthesis gas
Assignee: Imperial Chemical Industries Ltd
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Filing: 1985-10-07
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Granted: —
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Expires: 2005-10-07
Abstract
Abstract A raw ammonia synthesis gas, preferably containing an excess of nitrogen, is converted to synthesis ready amonia synthesis gas by two pressure swing adsorption (PSA) stages operated in succession. If the raw gas contains carbon monoxide this is chemically removed, eg by methanation, between the PSA stages. In the first PSA stage, C0 2 is removed and waste gas from the second PSA stage is preferably fed back to the first PSA stage for sweeping, purging or repressurising. In a preferred system the first PSA cycle includes a sweep with C0 2 -rich gas prior to depressurisation and purge with second PSA waste gas. In the second PSA stage inert medium boiling gases, and any unwaned nitrogen are removed as the waste gas.
Inventors
- 👤 Alwyn Pinto
- 👤 John Brian Hansen Johnson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 09:32
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/02; B01D53/04; B01D53/047; C; C01; C01B; C01B3/00; C01B3/02; C01B3/025; C01B3/50; C01B3/56; C01B32/00; C01B32/50; C10; C10K; C10K1/00; C10K1/34; B01D2256/00; B01D2256/16; B01D2257/00; B01D2257/10; B01D2257/102; B01D2257/50; B01D2257/502; B01D2257/504; B01D2259/00; B01D2259/40; B01D2259/404; B01D2259/406; B01D2259/4065; C01B2203/00; C01B2203/04; C01B2203/042; C01B2203/043; C01B2203/0465; C01B2203/0475; Y; Y02; Y02C; Y02C20/00; Y02C20/40; Y02P; Y02P20/00; Y02P20/151
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
131 words
A process for the production of synthesis-ready ammonia synthesis gas from a raw gas containing hydrogen, carbon dioxide, and medium boiling gas including nitrogen comprising removing carbon dioxide and unwanted medium boiling gas by pressure swing adsorption (PSA) characterised by (a) subjecting the raw gas to a first PSA system effective to remove carbon dioxide while leaving hydrogen and medium boiling gas largely unadsorbed; and (b) subjecting the unadsorbed gas to a second PSA system effective to separate therefrom a waste gas stream containing said unwanted medium boiling gas, including the excess, if any, of nitrogen; and wherein, if the unadsorbed gas leaving the first PSA system contains carbon monoxide, subjecting that unadsorbed gas to chemical removal of carbon monoxide prior to subjecting said unadsorbed gas to said second PSA system.
Claim 2
Dependent Claim
131 words
A process for the production of synthesis-ready ammonia synthesis gas from a raw gas containing hydrogen, carbon dioxide, and medium boiling gas including nitrogen comprising removing carbon dioxide and unwanted medium boiling gas by pressure swing adsorption (PSA) characterised by (a) subjecting the raw gas to a first PSA system effective to remove carbon dioxide while leaving hydrogen and medium boiling gas largely unadsorbed; and (b) subjecting the unadsorbed gas to a second PSA system effective to separate therefrom a waste gas stream containing said unwanted medium boiling gas, including the excess, if any, of nitrogen; and wherein, if the unadsorbed gas leaving the first PSA system contains carbon monoxide, subjecting that unadsorbed gas to chemical removal of carbon monoxide prior to subjecting said unadsorbed gas to said second PSA system.
Claim 3
Dependent Claim
42 words
A process according to claim 1 wherein the unadsorbed gas leaving the first PSA system contains carbon monoxide and is subjected to catalytic methanation to convert said carbon monoxide to methane prior to subjecting said unadsorbed gas to the second PSA system.
Claim 4
Dependent Claim
115 words
A process according to claim 1 or claim 2 wherein the raw gas has a (H 2 + CO)/(MB - CO) molar ratio in the range 1.25 to 2.5, where H 2 , C0, and MB represent the molar proportions of hydrogen, carbon monoxide and total medium boiling gas (including carbon monoxide) respectively, a carbon dioxide content in the range 10 to 25X v /v, and at least 90% v /v of the medium boiling gas is nitrogen, and in the second PSA system some nitrogen, as well as other unwanted medium boiling gas, is removed to give a synthesis ready ammonia synthesis gas having a hydrogen:nitrogen molar ratio in the range 2.5 to 3.1.
Claim 5
Dependent Claim
29 words
A process according to any one of claims 1 to 3 wherein part of the gas leaving the second PSA system is fed back to the first PSA system.
Claim 6
Dependent Claim
34 words
A process according to claim 4 wherein the gas fed back to the first PSA system is used in said first PSA system to repressurise, at least partially, beds of said first PSA system.
Claim 7
Dependent Claim
24 words
A process according to claim 4 or claim 5 wherein the gas fed back to the first PSA system is the waste gas stream.
Claim 8
Dependent Claim
26 words
A process according to any one of claims 1 to 6 wherein the PSA cycle of at least the first PSA system includes a purge step.
Claim 9
Dependent Claim
52 words
A process according to claim 7 wherein the PSA cycle of the first PSA system includes a counter-current depressurisation step followed by the purge step and the gases released in said counter-current depressurisation and purge steps are collected separately as, respectively, a carbon dioxide-rich gas stream and a carbon dioxide-lean gas stream.
Claim 10
Dependent Claim
31 words
A process according to claim 7 or claim 8 wherein the gas used for the purge step is at least part of the waste gas stream from the second PSA system.
Claim 11
Dependent Claim
30 words
A process according to any one of claims 1 to 9 wherein the PSA cycle of the first PSA system includes a co-current sweep step prior to a depressurisation step.
Claim 12
Dependent Claim
18 words
A process according to claim 10 wherein the gas released in the sweep step is used for repressurisation
Claim 13
Dependent Claim
26 words
A process according to claim 10 wherein the gas released in the sweep step is recycled to the raw gas fed to the first PSA system.
Claim 14
Dependent Claim
33 words
A process according to claim 10 wherein the PSA cycle of the first PSA system includes a purge step and the gas released in the sweep step is used for the purge step.
Claim 15
Dependent Claim
32 words
A process according to any one of claims 10 to 13 wherein the gas used for the sweep step is at least part of the waste gas from the second PSA system.
Claim 16
Dependent Claim
24 words
A process according to any one of claims 10 to 13 wherein the gas used for the sweep step is a carbon dioxide-rich gas.
Claim 17
Dependent Claim
42 words
A process according to claim 15 wherein the first PSA cycle includes a counter-current depressurisation step releasing a carbon dioxide-rich gas and at least part of that carbon dioxide-rich gas released in said counter-current depressurisation step is used as the sweep gas.
References Cited (Backward Citations)
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