Pressure management for slurry polymerization

Patent metadata

Field	Value
Publication number	US-9469707-B2
Application number	US-201514962228-A
Country	US
Kind code	B2
Filing date	Dec 8, 2015
Priority date	Oct 31, 2012
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

Processes and systems for the production for pressure management of a polymerization product flowing from a loop polymerization reactor to a separation vessel in a slurry polymerization system are disclosed herein. For example, a process comprises withdrawing a polymerization product slurry from a loop polymerization reactor, conveying the polymerization product slurry through a first line comprising a continuous take-off valve to yield a mixture comprising a vapor phase, wherein the mixture exits the continuous take-off valve, and conveying the mixture through a second line comprising a flashline heater so that the mixture has a Froude number in a range from about 5 to about 100.

First claim

What is claimed is:

1. A process for pressure management of a polymerization product in slurry polymerization, the process comprising:
withdrawing a polymerization product slurry from a loop polymerization reactor;
conveying the polymerization product slurry through a first line comprising a continuous take-off valve, to yield a mixture comprising a vapor phase, wherein the mixture exits the continuous take-off valve and wherein the vapor phase of the mixture comprises greater than 0.0000% by weight of the mixture exiting the continuous take-off valve; and
conveying the mixture through a second line comprising a flashline heater so that the mixture has a Froude number in a range from about 5 to about 100.

2. The process of claim 1 , wherein the Froude number is defined as:
Fr= V /( D*g ) 0.5

where V is an average velocity (units of ft/s) of the mixture in the flashline heater, g is the gravitational constant (322 ft/s 2 ), and D is an internal pipe diameter (units of ft) of the flashline heater.

3. The process of claim 1 , wherein the Froude number of the mixture conveyed through the
flashline heater is in a range of about 10 to about 60.

4. The process of claim 1 , wherein a drop in pressure of the first line is less than a drop in pressure of the second line.

5. The process of claim 1 , wherein the vapor phase of the mixture comprises greater than 1% by weight of the mixture exiting the continuous take-off valve.

6. The process of claim 1 , wherein the vapor phase of the mixture comprises greater than 2% by weight of the mixture exiting the continuous take-off valve.

7. The process of claim 1 , wherein the vapor phase of the mixture comprises greater than 3% by weight of the mixture exiting the continuous take-off valve.

8. The process of claim 1 , wherein the vapor phase of the mixture comprises greater than 5% by weight of the mixture exiting the continuous take-off valve.

9. The process of claim 1 , wherein the polymerization product slurry comprises a solid polymer and a liquid phase of a diluent, wherein the mixture further comprises the solid polymer, wherein the vapor phase of the mixture comprises at least a portion of the diluent.

10. A process for pressure management of a polymerization product slurry withdrawn from a loop polymerization reactor in slurry polymerization, the process comprising:
conveying the polymerization product slurry through a continuous take-off valve;
converting the polymerization product slurry to a mixture comprising a vapor phase, wherein the mixture exits the continuous take-off valve and wherein the vapor phase of the mixture comprises greater than 0.0000% by weight of the mixture exiting the continuous take-off valve; and
conveying the mixture through a flashline heater, wherein the mixture conveyed through the flashline heater has a Froude number in a range of 5 to 100.

11. The process of claim 10 , wherein the Froude number is defined as:
Fr= V /( D*g ) 0.5

where V is an average velocity (units of ft/s) of the mixture in the flashline heater, g is the gravitational constant (32.2 ft/s 2 ), and D is an internal pipe diameter (units of ft) of the flashline heater.

12. The process of claim 10 , wherein the mixture conveyed through the flashline heater has a Froude number in a range of 10 to 60.

13. The process of claim 10 , wherein a drop in pressure of a first line comprising the continuous take-off valve is less than a drop in pressure of a second line comprising the flashline heater.

14. The process of claim 10 , wherein the polymerization product slurry comprises a solid polymer and a liquid phase of a diluent, wherein the mixture further comprises the solid polymer, and wherein the vapor phase of the mixture comprises at least a portion of the diluent.

15. The process of claim 14 , wherein the solid polymer comprises polyethylene, wherein the diluent comprises isobutane.

16. The process of claim 10 , wherein the vapor phase of the mixture comprises greater than 1% by weight of the mixture exiting the continuous take-off valve.

17. The process of claim 10 , wherein the vapor phase of the mixture comprises greater than 3% by weight of the mixture exiting the continuous take-off valve.

18. The process of claim 10 , wherein the vapor phase of the mixture comprises greater than 5% by weight of the mixture exiting the continuous take-off valve.

19. The process of claim 1 , wherein the vapor phase of the mixture comprises greater than 5% by weight of the mixture exiting the continuous take-off valve.

20. The process of claim 9 , wherein the solid polymer comprises polyethylene, wherein the diluent comprises isobutane.

Assignees

• Chevron Phillips Chemical Co Lp
• Chevron Philips Chemical Company Lp

Inventors

• Kufeld Scott E
• Kreischer Bruce E
• Hottovy John D

Classifications

• C08F2/01 Primary

  characterised by special features of the polymerisation apparatus used · CPC title

• C08F2/00

  Processes of polymerisation · CPC title

• B01J2219/00162

  controlling the pressure · CPC title

• B01J2219/00231

  at the reactor inlet · CPC title

• C08F10/02

  Ethene · CPC title