Process

Patent metadata

Field	Value
Publication number	US-2016237182-A1
Application number	US-201615141017-A
Country	US
Kind code	A1
Filing date	Apr 28, 2016
Priority date	Mar 16, 2012
Publication date	Aug 18, 2016
Grant date	—

Abstract

The present invention relates to the treatment and recycle of effluent streams from a polymerisation process, and in particular provides a polymerisation process comprising the steps of: 1) Polymerising a monomer and a comonomer in a polymerisation reaction, 2) Withdrawing an effluent stream comprising solid polymer and a mixture comprising unreacted monomer and unreacted comonomer, and passing the effluent to a high pressure recovery system comprising a. a high pressure separation step for separating a vapour comprising unreacted monomer and unreacted comonomer from said solids, and b. a high pressure recycle system for recycling a portion of the vapour to the polymerisation reaction, 3) Passing the solids from the high pressure recovery system to a low pressure recovery system comprising a. a low pressure separation step for separating further unreacted monomer and unreacted comonomer from said solids, and b. a low pressure recycle system for recycling at least a portion of the unreacted monomer and unreacted comonomr to the polymerisation reaction, characterised in that a portion of the vapour separated in step 2(a) is passed to the low pressure recovery system.

First claim

1 - 15 . (canceled)

16 . A process for enhancing the separation of monomer components from light components other than monomer, which process comprises:
A) Providing a first stream comprising monomer and light components other than monomer, B) Passing the first stream to a first separator at a first pressure to separate a gaseous second stream comprising at least some of the light components other than monomer and provide a liquid third stream comprising monomer, C) Passing a portion of the third stream and a fourth stream comprising monomer and light components other than monomer to a second separator at a second pressure which is lower than the first pressure to separate a gaseous fifth stream comprising at least some of the light components other than monomer from the fourth stream and provide a liquid sixth stream comprising monomer.

17 . A process according to claim 16 wherein the first pressure is at least 0.5 MPa (5 bar).

18 . A process according to claim 16 wherein the second pressure is less than 0.5 MPa (5 bar), and more preferably is less than 0.4 MPa (4 bar).

19 . A process according to claim 16 wherein the pressure difference between the first and second pressures is at least 0.2 MPa (2 bar), more preferably at least 0.3 MPa (3 bar).

20 . A process according to claim 16 wherein the second separator is preferably at a pressure of less than 0.4 MPa (4 bar) and a temperature of less than 10° C.

21 . A process according to claim 16 wherein the monomer is ethylene or propylene, most preferably ethylene.

22 . A process according to claim 16 wherein fresh diluent and/or fresh comonomer is passed to the second separator.

23 . A process according to claim 16 which is applied to a polymerisation process operating in one or more reactors.

24 . A process according to claim 23 wherein there are at least two reactors operating in series.

25 . A process according to claim 23 which has a monomer efficiency in excess of 99.5%, for example of 99.6% and above, and most preferably of 99.7% and above.

26 . A process according to claim 23 wherein comonomer is fed to the polymerisation process and the process has a comonomer efficiency in excess of 95%, for example of 97% and above, and most preferably of 98% and above.

27 . A process according to claim 23 wherein the first separator is operated to provide a separation of hydrogen, nitrogen and methane from monomer and heavier components. 28 (new). A process according to claim 23 wherein the second stream is cooled to less than −10° C. whilst maintaining pressure at 0.5 MPa (5 bar) and above, preferably 0.7 MPa (7 bar) and above.

29 . A process according to claim 23 wherein the second separator is at a pressure of less than 0.4 MPa (4 bar) and at a temperature of less than −10° C. and preferably is part of a low pressure recovery system.

30 . A process according to claim 23 comprising:
1) Polymerising a monomer and a comonomer in a polymerisation reaction,
2) Withdrawing an effluent stream comprising solid polymer and a mixture comprising unreacted monomer and unreacted comonomer, and passing the effluent to a high pressure recovery system comprising
a. a high pressure separation step for separating a first vapour stream comprising unreacted monomer and unreacted comonomer from said solids, and
b. a high pressure recycle system for recycling a portion of the first vapour stream to the polymerisation reaction, said high pressure recycle system comprising
i. the first separator at a pressure greater than 0.5 MPa (5 bar) for separating the second stream comprising at least a portion of light components other than monomer in the first vapour stream and the third stream which is a liquid stream comprising condensed portions of the first vapour stream,
3) Passing the solids from the high pressure recovery system to a low pressure recovery system comprising
a. a low pressure separation step for separating further unreacted monomer and unreacted comonomer from said solids, and
b. a low pressure recycle system for recycling at least a portion of the further unreacted monomer and unreacted comonomer to the polymerisation reaction, said low pressure recycle system comprising
i. the second separator which operates at a pressure of less than 0.5 MPa (5 bar), preferably less than 0.4 MPa (4 bar), and at a temperature of less than −10° C.

31 . A process according to claim 30 wherein at least two reactors are operated in parallel and effluent stream from each is withdrawn, combined and passed to a common recovery system.

32 . A process according to claim 30 wherein at least two reactors are operated in series, and an effluent stream is withdrawn from the last reactor in series for passage to the high pressure recovery system and then to the low pressure recovery system.

33 . A process according to claim 30 wherein the portion of the third stream which is passed to the second separator comprises at least 1% by weight of the vapour separated in step 2(a).

34 . A process according to claim 30 wherein the portion of the third stream which is passed to the second separator comprises between 20 and 40 wt % of the vapour separated in step 2(a).

35 . A process according to claim 30 wherein a portion of the overhead stream from the separator in the low pressure recovery system is purged from the system.

Assignees

• Ineos Europe Ag

Inventors

• Marissal Daniel
• Van Breuseghem Philip
• Walworth Brent R

Classifications

• C08F2/06

  Organic solvent · CPC title

• C07C7/00

  Purification; Separation; Use of additives (working-up undefined gaseous mixtures obtained by cracking hydrocarbon oils C10G70/00) · CPC title

• C08F2/001

  Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer (C08F295/00, C08F297/00 take precedence) · CPC title

• C08F6/005 Primary

  from solid polymers · CPC title

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title