Solvent recycle from heavies removal column

Patent metadata

Field	Value
Publication number	US-2017342002-A1
Application number	US-201715588906-A
Country	US
Kind code	A1
Filing date	May 8, 2017
Priority date	May 25, 2016
Publication date	Nov 30, 2017
Grant date	—

Abstract

A process is presented for the recovery of solvent used in an alkylation process. The solvent removes heavy hydrocarbons from a C4 stream. The C4 stream is passed to an alkylation unit to generate an alkylate product. A portion of the solvent is carried over with the C4 stream and needs to be recovered to reduce the aromatics content in the C4 stream, to reduce any deleterious effects of the aromatics in downstream processing.

First claim

1 . A process for the recovery of solvent, comprising:
passing a hydrocarbon stream to a dehydrogenation unit to generate a first process stream comprising olefins; contacting the first process stream with a solvent stream in a contact cooler to generate an olefins stream, and a second process stream comprising solvent; passing the olefins stream to a heavies removal column to generate a heavies overhead stream comprising olefins, and a heavies bottoms stream comprising heavies and recovered solvent; and passing a portion of the heavies bottoms stream to the contact cooler.

2 . The process of claim 1 wherein the portion of the heavies bottoms stream is between 5% and 95% of the bottoms stream.

3 . The process of claim 2 wherein the portion of the heavies bottoms stream is between 25% and 90% of the bottoms stream.

4 . The process of claim 1 wherein the hydrocarbon stream comprises normal butane or isobutane or a mixture of butane and isobutane.

5 . The process of claim 1 wherein the contact cooler generates a cooled process stream.

6 . The process of claim 5 wherein the cooled process stream is compressed to generate a compressed stream.

7 . The process of claim 6 wherein the compressed stream is treated in a chloride treater unit to generate a treated stream.

8 . The process of claim 7 wherein the treated stream is passed to separation unit to generate a light stream comprising light gases, and a C4 stream.

9 . The process of claim 8 wherein the effluent stream is passed to a deethanizer or a depropanizer to generate a deethanizer or depropanizer overhead stream and the olefins stream.

10 . A process for producing alkylate, comprising:
passing a butane stream, comprising isobutane to a dehydrogenation unit to generate a first process stream comprising butenes; passing the first process stream and a cooling solvent to a contact cooler to generate a cooled process stream; passing the cooled process stream to a treatment unit to generate a treated stream comprising butenes; passing the treated stream to a heavies removal column to generate an overhead stream comprising butenes, and a bottoms stream comprising heavies and solvent; passing the overhead stream to an alkylation unit to generate an alkylate process stream; and passing a portion of the bottoms stream to the contact cooler, wherein the bottoms stream comprises a part of the cooling solvent.

11 . The process of claim 10 wherein the portion of the bottoms stream is between 5% and 95% of the bottoms stream.

12 . The process of claim 10 further comprising passing the alkylate process stream to a debutanizer to generate an alkylate product stream and a C4 overhead stream.

13 . The process of claim 12 further comprising:
passing the C4 overhead stream to a deisobutanizer to generate an iso-C4 overhead stream comprising isobutane, and a stream comprising normal C4s; and
passing a portion the iso-C4 overhead stream to the alkylation unit.

14 . The process of claim 12 further comprising passing a portion of the iso-C4 overhead stream to the dehydrogenation unit.

15 . The process of claim 13 further comprising passing the stream comprising normal C4s. to the dehydrogenation unit.

16 . A process for producing alkylate with reduced solvent consumption, comprising:
passing a first process stream comprising butenes to a contact cooler; passing a solvent stream to the contact cooler to generate a cooled process stream, and a waste solvent stream; passing the cooled process stream to a C4 recovery unit to generate a light gas stream, a C2− stream, and a C4 process stream; passing the C4 process stream to a heavies removal column to generate a C4 overhead stream comprising C4 olefins, and a bottoms stream comprising solvent and C5+ hydrocarbons; passing the C4 overhead stream to an alkylation unit to generate an alkylate process stream; and passing a portion of the bottoms stream to the contact cooler, wherein the bottoms stream comprises a part of the cooling solvent.

17 . The process of claim 16 wherein the portion of the bottoms stream is between 5% and 95% of the bottoms stream.

18 . The process of claim 16 wherein recovering the C4 process stream from the recovery unit comprises:
passing the cooled process stream to a compressor to generate a compressed stream;
passing the compressed stream to a chloride treater to generate a treated stream;
passing the treated stream to a drier to generate a dried stream;
passing the dried stream to a cold box separation unit to generate a light gas stream and a condensed C4 stream; and
passing the condenses C4 stream to a deethanizer to generate a C2− overhead stream and the C4 process stream.

19 . The process of claim 16 further comprising passing the alkylate process stream to a light ends separation unit to generate a C4 stream, and an alkylate product stream.

20 . The process of claim 19 further comprising:
passing the C4 stream to a deisobutanizer unit to generate an n-C4 stream and a iso-C4 stream; and
passing the iso-C4 stream to the alkylation unit.

Assignees

• Uop Llc

Inventors

• Zavala Raul
• Luebke Charles P
• Kanyuh Adam J

Classifications

• C10G2400/20

  C2-C4 olefins · CPC title

• C07C7/11

  by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids · CPC title

• C07C7/04

  by distillation · CPC title

• C10G9/00

  Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils · CPC title

• C07C5/327

  Formation of non-aromatic carbon-to-carbon double bonds only · CPC title