A source gas introduction line for introducing source gas containing CO.sub.2, a first membrane separator for membrane-separating CO.sub.2 from source gas, a first permeable gas discharge line for discharging first permeable gas permeated by membrane separation of the first membrane separator, a first non-permeable gas discharge line for discharging first non-permeable gas not permeated by membrane separation of the first membrane separator, a second membrane separator provided at a downstream side of the first membrane separator and for further membrane-separating CO.sub.2 from the first non-permeable gas, a second permeable gas discharge line for discharging second permeable gas permeated by membrane separation of the second membrane separator, a second permeable gas return line branched from a part of the second permeable gas discharge line and for returning the second permeable gas to a source gas side, and a CO.sub.2 concentration meter are included.

A contaminant removal system for removing a contaminant from an environment includes a gas separator, a scrubber-separator downstream of the gas separator, and a stripper-separator downstream of the scrubber-separator. The gas separator is configured to receive a cabin air stream from the environment and concentrate the contaminant from the cabin air stream to produce a concentrated cabin air stream. The cabin air stream includes the contaminant, and the concentrated cabin air stream has a higher concentration of the contaminant than the cabin air stream. The scrubber-separator is configured to absorb the contaminant from the concentrated cabin air stream into a liquid sorbent and discharge a clean air stream to the environment. The stripper-separator is configured to desorb the contaminant from the liquid sorbent into a contaminant stream.

Recovering helium from a gaseous stream includes contacting an acid gas removal membrane with a gaseous stream to yield a permeate stream and a residual stream, removing a majority of the acid gas from the residual stream to yield a first acid gas stream and a helium depleted clean gas stream, removing a majority of the acid gas from the permeate stream to yield a second acid gas stream and a helium rich stream, and removing helium from the helium rich stream to yield a helium product stream and a helium depleted stream. A helium removal system for removing helium from a gaseous stream including hydrocarbon gas, acid gas, and helium includes a first processing zone including a first acid gas removal unit, a second processing zone including a second acid gas removal unit, a third processing zone, and a helium purification unit.

Disclosed are systems and methods for producing oil and gas while removing hydrogen sulfide from fluids produced from oil and gas reservoirs. Hydrogen sulfide-selective membranes are used to remove hydrogen sulfide from bottlenecked plant process steps including hydrogen sulfide removal. In some embodiments of the present disclosure, plant processing efficiency is improved for processing of high temperature associated gas streams by using membranes while integrating heat from other existing process streams. In other embodiments of the present disclosure, plant processing efficiency is improved for processing of high temperature associated gas streams by using high temperature tolerant polymer membranes. Oil and/or gas production is increased.

The present invention addresses to a CO.sub.2/CH.sub.4 separation process using enzyme carbonic anhydrase, by means of a system with contactor membranes and a vessel containing absorbent liquids that have high salinity, which maintains a specific pH range to promote the formation of carbonate salts, in a way integrated into the CO.sub.2 capture process. Such a process results in a more efficient separation with conversion of CO.sub.2 into products with greater added value or, alternatively, sequestering CO.sub.2 more permanently, thus avoiding its emission into the atmosphere. The present invention is applied to natural gas streams with CO.sub.2 contents, more particularly in offshore oil fields or onshore natural gas processing units, as well as biogas streams.

A process for recovering sulfur and carbon dioxide from a sour gas stream, the process comprising the steps of: providing a sour gas stream to a membrane separation unit, the sour gas stream comprising hydrogen sulfide and carbon dioxide; separating the hydrogen sulfide from the carbon dioxide in the membrane separation unit to obtain a retentate stream and a first permeate stream, wherein the retentate stream comprises hydrogen sulfide, wherein the permeate stream comprises carbon dioxide; introducing the retentate stream to a sulfur recovery unit; processing the retentate stream in the sulfur recovery unit to produce a sulfur stream and a tail gas stream, wherein the sulfur stream comprises liquid sulfur; introducing the permeate stream to an amine absorption unit; and processing the permeate stream in the amine absorption unit to produce an enriched carbon dioxide stream.

A process for sweetening a syngas stream, the process comprising the steps of: providing a syngas stream to a nonselective amine absorption unit, the sour syngas stream comprising syngas, carbon dioxide, and hydrogen sulfide; separating the syngas stream in the nonselective amine absorption unit to obtain an overhead syngas stream and an acid gas stream; introducing the acid gas stream to a membrane separation unit, the acid gas stream comprising hydrogen sulfide and carbon dioxide; separating the acid gas stream in the membrane separation unit to produce a retentate stream and a permeate stream, wherein the retentate stream comprises hydrogen sulfide, wherein the permeate stream comprises carbon dioxide; introducing the retentate stream to a sulfur recovery unit; processing the retentate stream in the sulfur recovery unit to produce a sulfur stream and a tail gas stream, wherein the sulfur stream comprises liquid sulfur.

Recovering helium from a gaseous stream includes contacting an acid gas removal membrane with a gaseous stream to yield a permeate stream and a residual stream, removing a majority of the acid gas from the residual stream to yield a first acid gas stream and a helium depleted clean gas stream, removing a majority of the acid gas from the permeate stream to yield a second acid gas stream and a helium rich stream, and removing helium from the helium rich stream to yield a helium product stream and a helium depleted stream. A helium removal system for removing helium from a gaseous stream including hydrocarbon gas, acid gas, and helium includes a first processing zone including a first acid gas removal unit, a second processing zone including a second acid gas removal unit, a third processing zone, and a helium purification unit.

A process is provided for treating a hydrocarbon gas stream comprising sending the hydrocarbon gas stream to a membrane unit to be separated into a residue stream and a permeate gas stream; then sending the permeate gas stream with or without undergoing compression to a solvent absorption unit to remove carbon dioxide and other impurities; and recovering a treated gas.

The present invention relates to a process for concurrently removing CO.sub.2 and SO.sub.2 from flue gas produced by a combustion process, comprising: (a) performing a combustion process by combusting a fuel and air in a combustion apparatus, thereby creating an exhaust stream comprising CO.sub.2 and SO.sub.2; (b) compressing the exhaust stream in a first compression step, thereby producing a first compressed gas stream; (c) providing a first membrane having a feed side and a permeate side, and being selectively permeable to CO.sub.2 and SO.sub.2 over nitrogen and to CO.sub.2 and SO.sub.2 over oxygen; (d) passing at least a portion of the first compressed gas stream across the feed side; (e) withdrawing from the feed side a CO.sub.2- and SO.sub.2-depleted residue stream; (f) withdrawing from the permeate side at a lower pressure than the first compressed gas stream, a first permeate stream enriched in CO.sub.2 and SO.sub.2; (g) passing the first permeate stream to a separation process that produces a stream enriched in CO.sub.2 and a stream enriched in SO.sub.2.