Process to remove nitrogen and/or carbon dioxide from methane-containing streams
AssigneeSyntroleum Corporation
InventorsJ. Mark Landrum, Branch J. Russell, Kenneth Agee, Stephen LeViness
Life of this patent
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Abstract
A process for the removal of inert gases, such as nitrogen and carbon dioxide, from methane-containing gases, such as natural gas, including a first stage removal which lowers the total combined inert content to about less than 30% and a second stage removal utilizing a pressure swing adsorption process comprising one or more adsorbent beds comprising contracted titanosilicate-1 adsorbent, wherein the purified methane-containing gas contains less than about 6% total combined inerts.
Claims23
A process to purify a natural gas stream comprising between about 25% and 60% total inerts, the process comprising the steps of:
- (a) treating the natural gas stream with a first stage process comprising one or more processes of the group of selective membrane filtration, cryogenic distillation and amine scrubbing to produce a semi-purified natural gas stream comprising less than or equal to about 30% total combined inerts;
- and
- (b) treating the semi-purified natural gas stream with a second stage process in a pressure swing adsorption unit having one or more adsorbent beds having CTS-1 molecular sieve to obtain a product natural gas stream comprising less than about 5% total combined inerts.
A process to produce a pipeline quality natural gas comprising the steps of:
- (a) compressing a nitrogen-rich raw natural gas produced at low pressure to a first pressure between about 400 and about 1,000 psia to form a compressed feed gas stream;
- (b) feeding the compressed feed gas stream at a temperature greater than about 40° C. to the feed side of a membrane filtration system wherein the membrane is more permeable to methane than to nitrogen to produce a semi-purified stream;
- (c) recovering from the permeate side of the membrane, at a second pressure lower than the first pressure, a first permeate gas stream comprising less than or equal to about 30% nitrogen;
- (d) recompressing the first permeate gas stream in a second stage feed gas booster compressor to produce a pressure swing adsorption feed gas;
- and
- (e) recovering from the outlet of the membrane feed side a non-permeate gas stream enriched in nitrogen as compared to the compressed feed gas stream.
Dependencies are inferred from the claim text.