Apparatus and process for high pressure polymerization of ethylene

Patent metadata

Field	Value
Publication number	US-10835882-B2
Application number	US-201716065317-A
Country	US
Kind code	B2
Filing date	Jan 6, 2017
Priority date	Feb 26, 2016
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

Disclosed are an apparatus and a process for polymerizing ethylene under high pressure providing more than one injection point for one initiator injection pump.

First claim

What is claimed is:

1. An apparatus for high pressure polymerization of ethylene, comprising a high pressure reactor in which monomer is polymerized to form a product mixture comprising polymer and unreacted monomer, wherein the reactor is provided with more than one reaction zone and one or more injection pumps in fluid connection with the reactor, wherein each one of the one or more injection pumps fluidly connects to the reactor at multiple injection points;
and further wherein each respective injection point of the multiple injection points (a) is configured to provide initiator to a corresponding reaction zone of the more than one reaction zones; and (b) is provided with (b-1) a flow control valve and (b-2) a temperature controller of said corresponding reaction zone, said flow control valve and temperature controller being configured such that initiator flow to the respective injection point is controlled by the temperature controller acting on the flow control valve.

2. The apparatus of claim 1 , wherein total output of each injection pump is controlled by a pump discharge pressure controller.

3. The apparatus of claim 1 , wherein the reactor is a tubular reactor, an autoclave reactor, or a combination thereof.

4. The apparatus of claim 1 , wherein the reactor is a tubular reactor having at least three reaction zones and is provided with at least one cooling jacket in each reaction zone.

5. The apparatus of claim 4 , wherein the tubular reactor has a maximum internal diameter of at least 65 mm.

6. The apparatus of claim 1 , further comprising:
a primary compressor for compressing monomer to an intermediate pressure and a secondary compressor upstream of the reactor, wherein the second compressor is configured to compress the monomer to the pressure of the reactor;
a high pressure let down valve downstream of the reactor through which the product mixture from the high pressure reactor flows;
a separation system downstream of the high pressure let down valve having at least two stages for separating the product mixture into polymer and unreacted monomer; and
a recycle system for returning the unreacted monomer to the secondary compressor.

7. A process for high pressure polymerization of ethylene in a reactor, comprising the steps of:
compressing monomer in a primary compressor to an intermediate pressure and then mixing the monomer with recycled monomer and further compressing the monomer in a secondary compressor upstream of the reactor, wherein the monomer is compressed in the secondary compressor to the pressure of the reactor;
introducing compressed monomer into the high-pressure reactor, wherein the reactor is provided with more than one reaction zone;
injecting an initiator into the reactor at multiple injection points by one or more injection pumps, wherein each one of the one or more injection pumps conducts injection at multiple injection points;
and further wherein each respective injection point of the multiple injection points (a) provides initiator to a corresponding reaction zone of the more than one reaction zones, and (b) is provided with (b-1) a flow control valve and (b-2) a temperature controller of said corresponding reaction zone, such that flow of initiator to said respective injection point is controlled by the temperature controller acting on the flow control valve;

contacting the monomer in the reactor with the initiator under high pressure polymerization conditions for polymerization to form a product mixture;
releasing the product mixture through a high pressure let down valve, cooling the product mixture and separating the product mixture in a separation system having at least two stages into polymer and unreacted monomer; and
recycling the unreacted monomer to the secondary compressor.

8. The process of claim 7 , further comprising controlling total output of the injection pump with a pump discharge pressure controller.

9. The process of claim 7 , wherein the reactor is a tubular reactor, an autoclave reactor, or a combination thereof.

10. The process of claim 7 , wherein the reactor is a tubular reactor having at least three reaction zones and is provided with at least one cooling jacket in each reaction zone.

11. The process of claim 7 , wherein the initiator is an oxygen or organic free-radical initiator.

12. The process of claim 7 , wherein polymerization conditions in the reactor comprise temperatures from about 120° C. to about 335° C., and pressures from about 1200 bar (120 MPa) to about 3500 bar (350 MPa).

13. The process of claim 7 , further comprising injecting at least one modifier into the secondary compressor along with the monomer.

14. The process of claim 7 , wherein ethylene is the only monomer present and the polymer is an ethylene homopolymer.

15. The process of claim 7 , wherein one or more comonomers is present and the polymer is an ethylene copolymer.

16. The process of claim 15 , wherein the one or more comonomers is vinyl acetate, methyl acrylate, methacrylic acid, ethyl acrylate, butyl acrylate, acrylic acid, or mixtures thereof.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Clymans Paul J
• Lammens Henri A
• Cornelissen Philip H

Classifications

• B01J3/042 Primary

  in the form of a tube · CPC title

• C08F10/02

  Ethene · CPC title

• B01J4/008

  Feed or outlet control devices · CPC title

• B01J19/2415

  Tubular reactors · CPC title

• B01J3/02

  Feed or outlet devices therefor · CPC title