Natural gas treatment train
AssigneeMembrane Technology and Research, Inc.
InventorKaaeid A. Lokhandwala
Life of this patent
Estimating the term…
Abstract
A process train for treating a gas stream containing methane, nitrogen, and at least one of water vapor, acid gas, C.sub.3+ hydrocarbons and aromatic hydrocarbons, the gas stream typically, but not necessarily, being natural gas. The treatment train includes separation of methane from nitrogen by means of membranes that preferentially permeate methane and reject nitrogen. Preferred processes include both a dehydration step and an NGL removal step to treat the gas before it passes to the methane/nitrogen membrane separation step. The process train can also include additional steps, such as an acid gas removal step, or a cryogenic methane/nitrogen separation step.
Claims36
A treatment process for a gas stream comprising methane, nitrogen, water and C.sub.3+ hydrocarbons, comprising the following steps:
- (a) removing at least a portion of said water from said gas stream to produce a drier gas stream;
- (b) removing at least a portion of said C.sub.3+ hydrocarbons from said drier gas stream to produce a lighter gas stream;
- (c) providing a membrane having a feed side and a permeate side and being selective for methane over nitrogen;
- (d) passing said lighter gas stream across said feed side at a temperature no higher than about 0.degree. C.;
- (e) withdrawing from said feed side a residue stream depleted in methane and enriched in nitrogen compared with said lighter gas stream;
- (f) withdrawing from said permeate side a permeate stream enriched in methane and depleted in nitrogen compared with said lighter gas stream.
A gas-treating apparatus comprising:
- (a) a dehydration unit adapted to separate water from a gas stream containing water;
- (b) an NGL removal unit adapted to separate C.sub.3+ hydrocarbons from a gas stream containing C.sub.3+ hydrocarbons, and connected in gas-transferring relationship to said dehydration unit, so that gas can flow out of said dehydration unit and into said NGL removal unit;
- (c) a membrane separation unit containing a membrane selective for methane over nitrogen, whereby nitrogen can be separated from methane, and connected in gas-transferring relationship to said NGL removal unit so that gas can flow out of said NGL removal unit and into said membrane separation unit.
Dependencies are inferred from the claim text.