Butadiene heat integration process

Patent metadata

Field	Value
Publication number	US-11780789-B2
Application number	US-202017786813-A
Country	US
Kind code	B2
Filing date	Nov 5, 2020
Priority date	Dec 19, 2019
Publication date	Oct 10, 2023
Grant date	Oct 10, 2023

Abstract

Systems and methods for separating a mixture comprising C4 hydrocarbons and a solvent have been disclosed. The mixture is produced as a bottom stream of a rectifier column. The mixture is processed in at least two heating and flash-evaporating cycles to remove at least some C4 hydrocarbons as vapor streams. The resulted liquid stream is further degassed in a degasser column to produce a recycle vapor stream and a lean solvent stream.

First claim

What is claimed is:

1. A method of separating a mixture comprising (1) C 4 hydrocarbons and (2) a solvent, the method comprising:
separating the mixture in a rectifier column to produce a top stream comprising at least some C 4 hydrocarbons and a bottom stream comprising (a) primarily the solvent and (b) at least some C 4 hydrocarbons;
heating the bottom stream in a first heat exchange unit to form a first heated bottom stream at a first temperature;
flash-evaporating the first heated bottom stream to separate at least some C 4 hydrocarbons from the first heated bottom stream to form a first degassed bottom stream;
heating the first degassed bottom stream in a second heat exchange unit to form a second heated bottom stream at a second temperature;
flash-evaporating the second heated bottom stream to separate at least some C 4 hydrocarbons from the second heated bottom stream to form a second degassed bottom stream;
feeding at least a portion of the second degassed bottom stream as a degasser feed stream to a degasser column to further remove C 4 hydrocarbons from the solvent; and
removing at least some C 4 hydrocarbons from the degasser feed stream in the degasser column to produce a degasser top stream comprising the C 4 hydrocarbons in vapor phase, and a first hot lean solvent stream comprising primarily the solvent.

2. The method of claim 1 , further comprising:
prior to the step of flash-evaporating the second heated bottom stream, heating the first degassed bottom stream in an additional heat exchange unit installed up stream or downstream to the second heat exchange unit.

3. The method of claim 2 , wherein the additional heat exchange unit is operated with a low pressure steam as a heating medium.

4. The method of claim 1 , further comprising:
compressing the degasser top stream to form a compressed recycle stream; and
flowing the compressed recycle stream to the rectifier column.

5. The method of claim 4 , wherein the compressing is conducted using a compressor or a multiphase pump.

6. The method of claim 1 , further comprising:
prior to the feeding step, heating the second degassed bottom stream in a third heat exchange unit to form a third heated bottom stream at a third temperature;
flash-evaporating the third heated bottom stream to separate at least some C 4 hydrocarbons from the third heated bottom stream to form a third degassed bottom stream; and
feeding the third degassed bottom stream as a degasser feed stream to the degasser column configured to further remove C 4 hydrocarbons from the solvent.

7. The method of claim 6 , wherein the third exchange unit is operated using low pressure steam as a heating medium.

8. The method of claim 6 , wherein the flash-evaporating of the third heated bottom stream further produces a third vapor stream comprising primarily the C 4 hydrocarbons, and the method further comprises flowing the third vapor stream to the rectifier column.

9. The method of claim 1 , wherein the first hot lean solvent stream is flowed into the first heat exchange unit and/or the second heat exchange unit as a heating medium to form a second hot lean solvent stream.

10. The method of claim 9 , further comprising: prior to feeding the degasser feed stream to the degasser, cooling, in a fourth heat exchanger, the degasser feed stream with the cooled lean solvent stream as a cooling medium to form a cooled degasser feed stream and a heated lean solvent stream.

11. The method of claim 10 , wherein the heated lean solvent stream is used as a heating medium to heat a reboiler of a 1,3-butadiene refining column configured to purify a crude 1,3-butadiene stream, and optionally a reboiler of a propyne refining column configured to separate propyne from a hydrocarbon mixture.

12. The method of claim 11 , wherein the heated lean solvent stream is used as a heating medium to heat the reboiler of the propyne refining column and the reboiler of the 1,3-butadiene refining column in series.

13. The method of claim 10 , wherein the heated lean solvent stream is used as a heating medium to heat a reboiler of a 1,3-butadiene refining column and a feed vaporizer configured to vaporize C 4 hydrocarbon feed for an extractive distillation column.

14. The method of claim 13 , wherein the extractive distillation column is configured to separate the vaporized C 4 hydrocarbon feed to produce the mixture of C 4 hydrocarbons.

15. The method of claim 1 , wherein the flash-evaporating of the first heated bottom stream further produces a first vapor stream comprising primarily the C 4 hydrocarbons, and the flash-evaporating of the second heated bottom stream further produces a second vapor stream comprising primarily the C 4 hydrocarbons, wherein the first vapor stream and the second vapor stream are flowed to the rectifier column.

16. The method of claim 1 , wherein the C 4 hydrocarbons comprise 1-butene, 2-butene, n-butane, isobutane, isobutene, 1,3-butadiene, 1,2-butadiene, cis and trans butene isomers, C 4 acetylenes, propyne, or combinations thereof.

17. The method of claim 1 , wherein the removing at least some C 4 hydrocarbons from the degasser feed stream further produces a side stream comprising C 4 acetylene.

18. The method of claim 17 , wherein the side stream is further separated in an acetylene washer column to produce an acetylene stream comprising less than 30 wt. % C 4 acetylene.

19. The method of claim 1 , wherein the solvent comprises n-methyl-2-pyrrolidone, dimethyl formamide, or acetonitrile.

20. The method of claim 1 , wherein the first hot lean solvent stream comprises less than 0.01 wt. % C 4 hydrocarbons.

Assignees

• Sabic Global Technologies Bv

Inventors

• Abdelghani Mohamed Sabri

Classifications

• C07C7/005 Primary

  Processes comprising at least two steps in series · CPC title

• C07C7/04

  by distillation · CPC title

• Y02P20/10

  Process efficiency · CPC title