Process for the removal of carbon dioxide and heavy hydrocarbons
The invention provides a process to purify a gas stream by using an adsorbent bed and a secondary device to remove heavy hydrocarbons with a recycle stream then sent first to a vessel containing an amine solvent to remove acid gases including carbon dioxide and hydrogen sulfide and then in most embodiments of the invention sending the treated gas stream to a dehydration unit such as an adsorbent bed or to a triethylene glycol absorbent to remove water. The invention further provides improved integration of the process streams to allow for smaller amine solvent and dehydration units as compared to the prior art.
1. A process for treating a feed gas comprising:
sending said feed gas through an adsorbent bed and a secondary device to remove contaminants selected from the group consisting of C 5+ , an acidic gas comprising carbon dioxide, hydrogen sulfide or both, and water to produce a treated gas stream and a spent regeneration stream containing said contaminants; and
eventually sending said spent regeneration stream through a vessel containing an amine solvent to produce a partially treated gas stream and a waste stream comprising acid gas and water.
2. The process of claim 1 further comprising sending said partially treated gas stream to at least one adsorbent bed to absorb water and produce a dried treated gas stream.
3. The process of claim 1 further comprising sending said partially treated gas stream to a vessel containing triethylene glycol to absorb water and produce a dried treated gas stream.
4. The process of claim 1 wherein a portion of said feed is heated to produce a heated stream and returned to said adsorbent bed.
5. The process of claim 2 wherein a portion of said dried treated gas stream is sent as a regeneration gas stream to said at least one adsorbent bed to produce a wet stream to be removed from said at least one adsorbent bed.
6. The process of claim 5 wherein said wet stream is sent through a condenser to produce a liquid water stream.
7. The process of claim 1 wherein said spent regeneration gas is sent to a heavy knock out drum to produce a treated stream and a heavy hydrocarbon stream and then said heavy hydrocarbon stream is mixed with a portion of said spent regeneration gas to produce a fuel gas stream.
8. The process of claim 1 wherein said spent regeneration gas is sent to said vessel containing an amine solvent to produce a waste stream comprising carbon dioxide and hydrogen sulfide and a stream comprising water.
9. The process of claim 8 wherein said stream comprising water is sent to a dehydration unit to produce a lean recycle gas stream and a wet stream.
10. The process of claim 9 wherein said wet stream is cooled in a water knockout system to produce a liquid water stream and a recycle stream to be returned to said dehydration unit.
11. The process of claim 1 wherein said treated gas stream is sent through a dehydration unit to produce a dry hydrocarbon stream and a wet stream.
12. The process of claim 11 wherein said dry hydrocarbon stream is sent through a heavy hydrocarbon knock out unit to produce a recycle stream and a waste heavy hydrocarbon stream.
13. The process of claim 12 wherein said recycle stream is returned to said feed gas stream.
14. The process of claim 1 wherein said contaminants are sent to a heavy knock out drum to produce a waste stream comprising C 5+ , aromatic compounds, sulfur compounds and water and a stream to be sent to a dehydration unit.
15. The process of claim 1 wherein said waste stream further comprises hydrogen sulfide and is combined with a stream containing said contaminants to produce a fuel gas stream.
16. The process of claim 1 wherein said feed gas is treated without a separate dehydration unit.