Processes for recovering LPG from a reforming-zone effluent
Embodiments of apparatuses and methods for reforming of hydrocarbons including recovery of products are provided. In one example, a method comprises separating a reforming-zone effluent into a net gas phase stream and a liquid phase hydrocarbon stream. The net gas phase stream is separated for forming an H 2 -rich stream and a first liquid phase hydrocarbon stream. The H 2 -rich stream may be contacted with an adsorbent to form an H 2 -ultra rich stream and a gas stream. C 3 /C 4 hydrocarbons are absorbed from the gas stream with the liquid phase hydrocarbon stream. The gas stream may be contacted with an H 2 /hydrocarbon separation membrane to separate the PSA tail gas stream and form an H 2 -rich permeate stream and an H 2 depleted non-permeate residue stream.
1. A process for recovering C 3 /C 4 hydrocarbons from a reformate effluent stream, the process comprising:
separating, in a first separation zone, a reforming-zone effluent comprising H 2 , C 4 − hydrocarbons, and C 5 + hydrocarbons, including aromatics, to form a net gas phase stream comprising C 6 − hydrocarbons and H 2 and a liquid phase hydrocarbon stream comprising C 5 + hydrocarbons including aromatics;
separating, in a second separation zone, the net gas phase stream to form a first H 2 rich-stream and a gas stream that comprises H 2 , and C 4 − hydrocarbons;
cooling the gas stream to a temperature between approximately 15.6 and 71.1° C. (60 and 160° F.) to form a cooled gas stream;
cooling the liquid phase hydrocarbon stream to a temperature between approximately 15.6 and 71.1° C. (60 and 160° F.) to form a cooled liquid phase hydrocarbon stream;
absorbing C 3 /C 4 hydrocarbons from the cooled gas stream with the cooled liquid phase hydrocarbon stream in an absorbing zone to form a fuel gas stream and a C 3 /C 4 enriched liquid phase hydrocarbon stream;
separating the C 3 /C 4 enriched liquid phase hydrocarbon stream, in a third separation zone, into a liquid LPG product stream, and an overhead receiver vapor stream;
splitting the overhead receiver vapor stream into a first portion and a second portion; and
combining only the first portion of the overhead receiver vapor stream with the gas stream.
2. The process of claim 1 further comprising:
compressing the gas stream prior to cooling the gas stream in a compression zone to a pressure of between approximately 34.5 to 3,447 kPa (5 and 500 psig).
3. The process of claim 1 further comprising:
adjusting a ratio of the first portion to the second portion.
4. The process of claim 1 further comprising:
cooling the second portion of the overhead receiver vapor stream to a temperature between approximately −28.9 to 26.7° C. (−20 and 80° F.) to provide a cooled second portion; and,
separating the cooled second portion into a second fuel gas stream and a second LPG stream.
5. The process of claim 1 , wherein all of the liquid phase hydrocarbon stream is cooled and absorbs C 3 /C 4 hydrocarbons from the cooled gas stream.
6. The process of claim 1 wherein the second separation zone comprises a PSA zone and the gas stream comprises a PSA tail gas stream, and wherein a temperature of a feed to the PSA zone is between approximately 15.6 and 71.1° C. (60 and 160° F.) and a pressure of the feed to the PSA zone is between approximately 1,724 to 7,826 kPa (250 to 700 psig).
7. The process of claim 1 further comprising:
separating hydrogen, in a membrane separation zone, from the gas stream before cooling the gas stream.
8. A process for recovering C 3 /C 4 hydrocarbons from a reformate effluent stream, the process comprising:
separating, in a first separation zone, a reforming-zone effluent comprising H 2 , C 4 − hydrocarbons, and C 5 + hydrocarbons, including aromatics, to form a net gas phase stream comprising C 6 − hydrocarbons and H 2 and a liquid phase hydrocarbon stream comprising C 5 + hydrocarbons including aromatics;
separating, in a second separation zone, the net gas phase stream to form a first H 2 rich-stream and a gas stream that comprises H 2 , and C 4 + hydrocarbons;
cooling the gas stream to form a cooled gas stream;
cooling all of the liquid phase hydrocarbon stream to form a cooled liquid phase hydrocarbon stream;
absorbing C 3 /C 4 hydrocarbons from the cooled gas stream with the cooled liquid phase hydrocarbon stream in an absorbing zone to form a fuel gas stream and a C 3 /C 4 enriched liquid phase hydrocarbon stream;
separating the C 3 /C 4 enriched liquid phase hydrocarbon stream, in a third separation zone, into a liquid LPG product stream, and an overhead receiver vapor stream;
splitting the overhead receiver vapor stream into a first portion and a second portion; and
combining only the first portion of the overhead receiver vapor stream with the gas stream.
9. The process of claim 8 further comprising:
adjusting a ratio of the first portion to the second portion.
10. The process of claim 8 further comprising:
cooling the second portion of the overhead received vapor stream to a temperature between approximately −28.9 to 26.7° C. (−20 and 80° F.) to provide a cooled second portion; and,
separating the cooled second portion into a second fuel gas stream and a second LPG product stream.
11. The process of claim 8 wherein the second separation zone comprises a PSA zone and the gas stream comprises a PSA tail gas stream, and wherein a temperature of a feed to the PSA zone is between approximately 15.6 and 71.1° C. (60 and 160° F.) and a pressure of the feed to the PSA zone is between approximately 1,724 to 7,826 kPa (250 to 700 psig).
12. The process of claim 8 further comprising:
separating hydrogen, in a membrane separation zone, from the gas stream before cooling the gas stream.
13. A process for recovering C 3 /C 4 hydrocarbons from a reformate effluent stream, the process comprising:
separating, in a first separation zone, a reforming-zone effluent comprising H 2 , C 4 − hydrocarbons, and C 5 + hydrocarbons, including aromatics, to form a net gas phase stream comprising C 6 − hydrocarbons and H 2 and a liquid phase hydrocarbon stream comprising C 5 + hydrocarbons including aromatics;
separating, in a second separation zone, the net gas phase stream to form a first H 2 rich-stream and a gas stream that comprises H 2 , and C 4 − hydrocarbons;
separating hydrogen, in a membrane separation zone, from the gas stream to form a second H 2 rich-stream and a H 2 depleted gas stream;
absorbing C 3 /C 4 hydrocarbons from the H 2 depleted gas stream with the liquid phase hydrocarbon stream in an absorbing zone to form a fuel gas stream and a C 3 /C 4 enriched liquid phase hydrocarbon stream;
separating the C 3 /C 4 enriched liquid phase hydrocarbon stream, in a third separation zone, into a liquid LPG product stream, and an overhead receiver vapor stream;
splitting the overhead receiver vapor stream into a first portion and a second portion; and
combining only the first portion of the overhead receiver vapor stream with the H 2 depleted gas stream.
14. The process of claim 13 , wherein a molar ratio of liquid to gas in the absorbing zone is greater than 1.
15. The process of claim 13 , wherein all of the liquid phase hydrocarbon stream absorbs C 3 /C 4 hydrocarbons from the H 2 depleted gas stream.
16. The process of claim 13 , wherein the absorbing zone has an operating temperature of between approximately 15.6 and 71.1° C. (60 and 160° F.).