Multiple-stage heating for a flashline heater

Patent metadata

Field	Value
Publication number	US-12173094-B2
Application number	US-202318236271-A
Country	US
Kind code	B2
Filing date	Aug 21, 2023
Priority date	May 3, 2021
Publication date	Dec 24, 2024
Grant date	Dec 24, 2024

Abstract

Disclosed is a process for operating a flashline heater and a flashline separation system. In the process and system, heat is supplied to the flashline heater by a first steam stage followed by a second steam stage. The steam pressure is controlled by a steam control system such that the pressure in the first steam stage is not equal to the pressure in the second steam stage. Also disclosed is a process for retrofitting a steam control system in a flashline separation system of an olefin polymerization system at least by changing the number of steam stages in the flashline separation system to include a first steam stage followed by a second steam stage, and changing the stream pressure control scheme such that the pressure in the first steam stage is independently controlled to be not equal to the pressure in the second steam stage.

First claim

What is claimed is:

1. A process for operating a flashline heater in an olefin polymerization system, wherein the olefin polymerization system comprises a reactor and a discharge conduit extending between the reactor and the flashline heater, wherein the discharge conduit comprises a continuous take-off (CTO) valve, and wherein the flashline heater comprises a first steam stage and a second steam stage, the process comprising:
controlling a first pressure of steam in the first steam stage of the flashline heater to be equal to about a first value; and
controlling a second pressure of steam in the second steam stage of the flashline heater to be equal to about a second value,
wherein the first value is not equal to the second value, wherein the first value is in a range of from greater than 0 psig to about 15 psig, and wherein the second value is in a range of from greater than 0 psig to about 15 psig and
wherein the flashline heater comprises a plurality of segments, wherein at least one segment of the plurality of segments is in the first steam stage, and wherein at least one segment of the plurality of segments is in the second steam stage.

2. The process of claim 1 ,
wherein controlling the first pressure of steam in the first steam stage of the flashline heater to be equal to about the first value comprises:
measuring the first pressure of steam in the first steam stage; and
actuating a first valve to increase or decrease a flow rate of steam to a first heating jacket of the first steam stage of the flashline heater; and

wherein controlling the second pressure of steam in the second steam stage of the flashline heater to be equal to about the second value comprises:
measuring the second pressure of steam in the second steam stage; and
actuating a second valve to increase or decrease a flow rate of steam to a second heating jacket of the second steam stage of the flashline heater.

3. The process of claim 2 , wherein the first valve is in a first steam conduit of the first steam stage and the second valve is in a second steam conduit of the second steam stage.

4. The process of claim 3 , wherein measuring the first pressure of steam is performed by a first sensor located in the first steam conduit or in the first heating jacket, and wherein measuring the second pressure of steam is performed by a second sensor located in the second steam conduit or the second heating jacket.

5. The process of claim 2 , wherein the first heating jacket is positioned around at least a portion of the at least one segment of the plurality of segments that is in the first steam stage, wherein the second heating jacket is positioned around at least a portion of the at least one segment of the plurality of segments that is in the second steam stage.

6. The process of claim 1 , wherein the at least one segment of the plurality of segments in the second steam stage has a nominal diameter greater than a nominal diameter of the at least one segment of the plurality of segments in the first steam stage.

7. The process of claim 6 , wherein the nominal diameter of the at least one segment of the plurality of segments in the second steam stage is in a range of from 2 inches to 10 inches and the nominal diameter of the at least one segment of the plurality of segments is in the first steam stage is in a range of from 2 inches to 10 inches.

8. The process of claim 5 , wherein the at least one segment of the plurality of segments in the second steam stage has a nominal diameter greater than a nominal diameter of the at least one segment of the plurality of segments in the first steam stage.

9. The process of claim 8 , wherein the nominal diameter of the at least one segment of the plurality of segments in the second steam stage is in a range of from 2 inches to 10 inches and the nominal diameter of the at least one segment of the plurality of segments is in the first steam stage is in a range of from 2 inches to 10 inches.

10. The process of claim 5 , wherein the at least one segment of the first steam stage has a nominal diameter in a range of from 1 inch to 8 inches, wherein the at least one segment of the second steam stage comprises a first segment and a second segment, wherein the first segment has a nominal diameter in a range of from 2 inches to 10 inches, wherein the second segment has a nominal diameter in a range of from 2 inches to 10 inches, wherein the nominal diameter of the second segment is greater than the nominal diameter of the first segment.

11. The process of claim 10 , wherein the nominal diameter of the at least one segment of the first steam stage is greater than or equal to 2.5 inches, wherein the nominal diameter of the first segment of the second steam stage is greater than or equal to 3 inches, wherein the nominal diameter of the second segment of the second steam stage is greater than or equal to 4 inches.

12. The process of claim 1 , further comprising:
collecting condensate from the first steam stage of the flashline heater; and
collecting condensate from the second steam stage of the flashline heater.

13. A flashline separation system comprising:
a flashline heater having a first steam stage followed by a second steam stage;
a steam control system comprising:
a first controller configured to control a first pressure of steam in the first steam stage of the flashline heater to be equal to about a first value; and
a second controller configured to control a second pressure of steam in the second steam stage of the flashline heater to be equal to about a second value,
wherein the first value is not equal to the second value,
wherein the flashline heater comprises a plurality of segments, wherein at least one segment of the plurality of segments is in the first steam stage, and wherein at least one segment of the plurality of segments is in the second steam stage, and
wherein the at least one segment of the plurality of segments in the second steam stage has a nominal diameter greater than a nominal diameter of the at least one segment of the plurality of segments is in the first steam stage.

14. The flashline separation system of claim 13 , wherein the first steam stage of the flashline heater has a first heating jacket around at least a portion of the at least one segment of the plurality of segments that is in the first steam stage, and wherein the second steam stage of the flashline heater has a second heating jacket around at least a portion of the at least one segment of the plurality of segments that is in the second steam stage.

15. The flashline separation system of claim 14 , further comprising:
a first steam conduit connected to the first heating jacket; and
a second steam conduit connected to the second heating jacket.

16. The flashline separation system of claim 15 , wherein the steam control system further comprises:
a first valve positioned in the first steam conduit;
a second valve positioned in the second steam conduit;
a first sensor positioned in the first steam conduit or in the first heating jacket; and
a second sensor positioned in the second steam conduit or in the second heating jacket,
wherein the first controller is coupled to the first valve and to the first sensor, and
wherein the second controller is coupled to the second valve and to the second sensor.

17. The flashline separation system of claim 14 , further comprising:
one or more condensate tanks connected to the first heating jacket and the second heating jacket, wherein the one or more condensate tanks are configured to receive condensate from the first heating ja

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Li Hetian

Classifications

• B01D1/14

  with heated gases or vapours {or liquids} in contact with the liquid · CPC title

• B01D1/0082

  Regulation; Control · CPC title

• C08F6/005

  from solid polymers · CPC title

• B01D1/04

  Evaporators with horizontal tubes · CPC title

• C08F2/01 Primary

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