Process for recovering heat from a hydrocarbon separation

Patent metadata

Field	Value
Publication number	US-10315971-B2
Application number	US-201715814288-A
Country	US
Kind code	B2
Filing date	Nov 15, 2017
Priority date	Dec 29, 2016
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

Systems and processes for heat recovery associated with the separation of hydrocarbon components. Two compressors are used to compress a portion of an overhead vapor stream from a fractionation column. A pressure of the liquid portion of the compressed overhead is reduced and used to recover heat from an overhead of another separation zone having a fractionation column. Once the heat has been recovered the stream is recompressed. The recovered heat may be removed from the recompressed stream in a reboiler of another fractionation column. The fractionation columns may comprise a deethanizer stripper, propane-propylene splitter, and a depropanizer column.

First claim

The invention claimed is:

1. A process for separating hydrocarbons and recovering heat comprising:
separating a stream comprising C4− hydrocarbons in a first separation zone into an overhead stream and a C3+ bottoms stream;
separating the C3+ bottoms stream in a second separation zone into a propylene overhead stream and a bottoms stream comprising propane;
compressing the propylene overhead stream in a first compression zone configured to provide a compressed propylene overhead stream;
recovering heat from a first portion of the compressed propylene overhead stream in a heat exchange zone associated with the second separation zone;
condensing a second portion of the compressed propylene overhead stream in a separation vessel, the separation vessel providing a propylene vapor stream and a propylene liquid stream;
reducing a pressure of at least a portion of the propylene liquid stream to provide a reduced pressure stream;
recovering heat from the reduced pressure stream in a second heat exchange zone, the second heat exchange zone associated with the first separation zone and being configured to condense a portion of the overhead stream and provide a vaporized propylene stream;
compressing the vaporized propylene stream in a second compression zone configured to provide a re-compressed propylene stream; and,
mixing the re-compressed propylene stream with the second portion of the compressed propylene overhead stream in the separation vessel.

2. The process of claim 1 further comprising:
compressing the propylene vapor stream from the separation vessel in the second compression zone.

3. The process of claim 2 further comprising:
removing heat from the re-compressed propylene stream before the re-compressed propylene stream is mixed with the second portion of the compressed propylene overhead stream in the separation vessel.

4. The process of claim 3 wherein the heat is removed from the re-compressed propylene stream in a third heat exchange zone associated with a third separation zone configured to receive the bottoms stream from the second separation zone.

5. The process of claim 1 further comprising:
separating the first portion of the compressed propylene overhead stream in a fractionation column in the second separation zone.

6. The process of claim 1 further comprising:
recovering a second portion of the propylene liquid stream as a propylene product stream.

7. The process of claim 1 further comprising:
refluxing a third portion of the propylene liquid stream from the separation vessel to a fractionation column in the second separation zone.

8. The process of claim 1 wherein the first separation zone comprises two fractionation columns, and wherein the second separation zone comprises a fractionation column.

9. The process of claim 1 further comprising:
transferring heat from the re-compressed propylene stream to a third separation zone configured to receive the bottoms stream from the second separation zone.

10. A process for separating hydrocarbons and recovering heat comprising:
separating a stream comprising C4− hydrocarbons in a first separation zone configured to separate the stream into an overhead stream and a C3+ bottoms stream;
passing the C3+ bottoms stream to a second separation zone configured to separate the C3+ bottoms stream and provide a propylene overhead stream and a bottoms stream, the bottom stream including propane;
passing the bottoms stream of the second separation zone to a third separation zone;
passing the propylene overhead stream to a first compression zone configured to compress the propylene overhead stream and provide a compressed propylene overhead stream;
passing a first portion of the compressed propylene overhead stream to a heat exchange zone associated with the second separation zone configured to remove heat from the first portion of the compressed propylene overhead stream;
passing a second portion of the compressed propylene overhead stream to a separation vessel configured to allow the second portion of the compressed propylene overhead stream to be cooled and separate into a vapor propylene stream and a liquid propylene stream;
reducing a pressure of at least a portion of the liquid propylene stream to provide a reduced pressure stream, the reduced pressure stream comprising a mixture of liquid and vapor;
passing the reduced pressure stream to a second heat exchange zone associated with the first separation zone and configured to vaporize liquid in the reduced pressure stream and provide a vaporized propylene stream, wherein the second heat exchange zone also receives a portion of the overhead stream from the first separation zone;
passing the vaporized propylene stream to a second compression zone configured to compress the vaporized propylene stream and provide a re-compressed propylene stream; and,
passing the re-compressed propylene stream to the separation vessel.

11. The process of claim 10 further comprising:
passing the vapor propylene stream from the separation vessel to the second compression zone.

12. The process of claim 11 further comprising:
removing heat from the re-compressed propylene stream before the propylene is passed to the separation vessel.

13. The process of claim 12 further comprising:
passing the re-compressed propylene stream to a third heat exchange zone associated with the third separation zone; and,
then passing the re-compressed propylene stream from the third heat exchange zone to the separation vessel.

14. The process of claim 10 further comprising:
passing the first portion of the compressed propylene overhead stream from the first heat exchange zone to a fractionation column in the second separation zone.

15. The process of claim 10 further comprising:
recovering a second portion of the liquid propylene stream as a propylene product stream.

16. The process of claim 10 further comprising:
passing a third portion of the liquid propylene stream to a fractionation column in the second separation zone.

17. The process of claim 10 wherein the first separation zone comprises a fractionation column, and wherein the second separation zone comprises a fractionation column.

18. The process of claim 10 further comprising:
removing heat from the re-compressed propylene stream before the propylene is passed to the separation vessel.

Assignees

• Uop Llc

Inventors

• King Stephen T
• Van De Cotte Michael R
• Kanyuh Adam J
• Kozup Steven C

Classifications

• B01D3/143

  by two or more of a fractionation, separation or rectification step · CPC title

• B01D1/2881

  Compression specifications (e.g. pressure, temperature, processes) · CPC title

• C07C7/005 Primary

  Processes comprising at least two steps in series · CPC title

• B01D1/2846

  The compressed vapour is not directed to the same apparatus from which the vapour was taken off · CPC title

• B01D1/2856

  The compressed vapour is used for heating a reboiler or a heat exchanger outside an evaporator · CPC title