Pressure management for slurry polymerization

Patent metadata

Field	Value
Publication number	US-9238698-B2
Application number	US-201414492527-A
Country	US
Kind code	B2
Filing date	Sep 22, 2014
Priority date	Oct 31, 2012
Publication date	Jan 19, 2016
Grant date	Jan 19, 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
conveying the mixture through a second line comprising a flashline heater so that the mixture has a prouder number in a range from about 5 to about 100, wherein the flashline heater comprises a plurality of segments.

2. 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.

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

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

5. The process of claim 1 , wherein the conveying the mixture through the second line comprising the flashline heater comprises:
conveying the mixture through at least one segment of the plurality of segments of the flashline heater so that the mixture has a Froude number in a range from about 5 to about 100 in the at least one segment.

6. The process of claim 1 , wherein at least one of the plurality of segments has an inner diameter greater than an inner diameter of a preceding segment of the plurality of segments.

7. 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
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, wherein the flashline heater has a length and one or more inner diameters such that the flashline heater provides the polymerization product a residence time of greater than about 7.5 seconds.

8. The process of claim 1 , wherein the vapor phase of the mixture comprises greater than 0% by weight of the mixture in the first line.

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 as 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
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, wherein the flashline heater comprises a plurality of segments, wherein at least one of the plurality of segments has an inner diameter greater than an inner diameter of a preceding segment of the plurality of segments.

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

12. 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.

13. The process of claim 10 , wherein a drop in pressure of a first line comprising the continuous take-off valve is greater 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. 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
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, wherein the flashline heater has a length and one or more inner diameters such that the flashline heater provides a residence time of greater than about 7.5 seconds.

17. 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
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, wherein the continuous take-off valve has a diameter of about 0.1 inch to about 8 inches.

18. The process of claim 10 , wherein the vapor phase of the mixture comprises greater than 0% by weight of the mixture which exits the continuous-take off valve.

19. The process of claim 7 , wherein the flashline heater comprises a plurality of segments, wherein at least one of the plurality of segments has an inner diameter greater than an inner diameter of a preceding segment of the plurality of segments.

20. The process of claim 7 , wherein the vapor phase of the mixture comprises greater than 0% by weight of the mixture in the first line.

21. The process of claim 7 , 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.

22. The process of claim 7 , wherein the continuous take-off valve has a diameter of about 1 inch to about 8 inches.

23. The process of claim 7 , wherein the Froude number of the mixture conveyed through the flashline heater is in a range of about 10 to about 60.

24. The process of claim 16 , wherein the flashline heater comprises a plurality of segments, wherein at least one of the plurality of segments has an inner diameter greater than an inner diameter of a preceding segment of the plurality of segments.

25. The process of claim 16 , wherein the vapor phase of the mixture comprises greater than 0% by weight of the mixture which exits the continuous take-off valve.

26. The process of claim 16 , wherein the polymerization product slurry comprises a solid polymer and a liquid phase of a diluent, wherein the mixture further comprises

Assignees

• Chevron Phillips Chemical Co

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

• B01J2219/00006

  Large-scale industrial plants · CPC title

• C08L23/06

  Polyethylene · CPC title

• C08F2/14

  Organic medium · CPC title