Method and system for preventing accumulation of solids in a distillation tower

Patent metadata

Field	Value
Publication number	US-9874395-B2
Application number	US-201414516713-A
Country	US
Kind code	B2
Filing date	Oct 17, 2014
Priority date	Dec 6, 2013
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

The present disclosure provides a method for preventing accumulation of solids in a distillation tower. The method includes introducing a feed stream into a controlled freeze zone section of a distillation tower; forming solids in the controlled freeze zone section from the feed stream; discontinuously injecting a first freeze-inhibitor solution into the controlled freeze zone section toward a location in the controlled freeze zone section that accumulates the solids; and destabilizing accumulation of the solids from the location with the first freeze-inhibitor solution.

First claim

What is claimed is:

1. A method for preventing accumulation of solids in a distillation tower, the method comprising:
introducing a feed stream into a controlled freeze zone section of the distillation tower;
forming the solids in the controlled freeze zone section from the feed stream;
detecting a temperature in the controlled freeze zone section;
comparing the detected temperature to an expected temperature range, wherein the expected temperature range is a range of temperatures at which the controlled freeze zone operates normally;
discontinuously injecting a first freeze-inhibitor solution into the controlled freeze zone section toward a location in the controlled freeze zone section that accumulates the solids, wherein the first freeze-inhibitor solution is injected into the controlled freeze zone section when the detected temperature is outside of the expected temperature range by a positive amount and wherein the temperature of the first freeze-inhibitor solution is controlled independently of the flow rate of the first freeze-inhibitor solution being injected into the controlled freeze zone section; and
destabilizing accumulation of the solids from the location with the first freeze-inhibitor solution.

2. The method of claim 1 , wherein the first freeze-inhibitor solution comprises any carbon dioxide solubilizing solvent that remains unfrozen in the controlled freeze zone section.

3. The method of claim 1 , wherein the first freeze-inhibitor solution comprises at least one of light hydrocarbons and light alcohols.

4. The method of claim 1 , wherein the first freeze-inhibitor solution comprises at least one of ethane, methanol, propane and butane.

5. The method of claim 1 , wherein discontinuously injecting the first freeze-inhibitor solution comprises releasing the first freeze-inhibitor solution from the location.

6. The method of claim 1 , wherein the location comprises at least one of a spray assembly of the controlled freeze zone section and a first freeze-inhibitor injection piping arrangement adjacent to a controlled freeze zone wall of the controlled freeze zone section.

7. The method of claim 1 , further comprising injecting a second freeze-inhibitor solution into an upper section of the distillation tower toward a location in the upper section that accumulates the solids.

8. The method of claim 7 , wherein the location in the upper section comprises a second freeze-inhibitor injection piping arrangement adjacent to an upper section wall of the upper section.

9. The distillation tower of claim 7 , wherein the second freeze-inhibitor solution comprises at least one of light hydrocarbons and light alcohols.

10. The method of any one of claim 7 , wherein the second freeze-inhibitor solution comprises at least one of ethane, methanol, propane and butane.

11. The method of claim 1 , further comprising producing hydrocarbons from the feed stream.

12. The method of claim 1 , further comprising controlling an angle at which the first freeze-inhibitor solution is injected.

13. The method of claim 1 , wherein the controlled freeze zone wall comprises an external surface and wherein the temperature is detected by a temperature sensor coupled to the external surface of the controlled freeze zone wall.

14. A distillation tower that prevents accumulation of solids in the distillation tower, the distillation tower comprising:
a stripper section constructed and arranged to separate a feed stream in the distillation tower at a temperature and pressure at which the feed stream forms no solid;
a controlled freeze zone section constructed and arranged to separate the feed stream in the distillation tower at a temperature and pressure at which the feed stream forms solids;
a temperature sensor configured to detect a temperature in the controlled freeze zone section; and
a first freeze-inhibitor injection mechanism, wherein the first freeze-inhibitor injection mechanism is constructed and arranged to inject a first freeze-inhibitor solution in the controlled freeze zone section discontinuously when the temperature detected by the temperature sensor exceeds a predetermined value amount and wherein the first freeze-inhibitor injection mechanism is constructed and arranged to independently control the temperature and the flow rate of the first freeze-inhibitor solution being injected into the controlled freeze zone section.

15. The distillation tower of claim 14 , wherein the first freeze-inhibitor solution comprises any carbon dioxide solubilizing solvent that remains unfrozen in the controlled freeze zone section.

16. The distillation tower of claim 14 , wherein the first freeze-inhibitor solution comprises at least one of light hydrocarbons and light alcohols.

17. The distillation tower of claim 14 , wherein the first freeze-inhibitor solution comprises at least one of ethane, methanol, propane and butane.

18. The distillation tower of claim 14 , further comprising at least one of a spray assembly of the controlled freeze zone section and a first freeze-inhibitor injection piping arrangement adjacent to a controlled freeze zone wall of the controlled freeze zone section.

19. The distillation tower of claim 14 , further comprising an upper section constructed and arranged to separate the feed stream in the distillation tower, wherein the upper section comprises a second freeze-inhibitor mechanism constructed and arranged to inject a second freeze-inhibitor solution in the upper section.

20. The distillation tower of claim 19 , wherein the second freeze-inhibitor solution comprises at least one of light hydrocarbons and light alcohols.

21. The distillation tower of claim 19 , wherein the second freeze-inhibitor solution comprises at least one of ethane, methanol, propane and butane.

22. A method for preventing accumulation of solids in a distillation tower, the method comprising:
providing a distillation tower, wherein the distillation tower comprises:
a stripper section constructed and arranged to separate a feed stream into a bottom liquid stream and a freezing zone vapor stream;
a controlled freeze zone section constructed and arranged to receive the freezing zone vapor stream from the stripper section and to separate the feed stream into solids and a methane-enriched vapor stream, wherein the controlled freeze zone section comprises a melt try assembly and a spray assembly;
a temperature sensor configured to detect a temperature in the controlled freeze zone section; and
a first freeze-inhibitor injection mechanism that is constructed and arranged to inject a first freeze-inhibitor solution in the controlled freeze zone section, wherein the first freeze-inhibitor injection mechanism is coupled to the spray assembly and wherein the first freeze-inhibitor injection mechanism is constructed and arranged to independently control the temperature and the flow rate of the first freeze-inhibitor solution being injected into the controlled freeze zone section;

introducing a feed stream into a controlled freeze zone section of the distillation tower;
separating the feed stream into solids and a methane-enriched vapor stream;
cooling the methane-enriched vapor stream to form a cooled stream;
introducing a liquid spray to the controlled freeze zone section from the spray assembly, wherein the liquid spray comprises at least a portion of the cooled stream;
detecting a temperature in the controlled freeze zone section;
comparing the detected temperature to an expected temperatur

Assignees

• Valencia Jaime A
• Northrop Paul Scott
• Exxonmobil Upstream Res Co

Inventors

• Valencia Jaime A
• Northrop Paul Scott

Classifications

• F25J3/061

  Natural gas or substitute natural gas · CPC title

• F25J2200/02

  in a single pressure main column system · CPC title

• F25J3/067

  separation of carbon dioxide (production of carbon dioxide in general C01B32/00) · CPC title

• F25J2200/50

  using multiple (re-)boiler-condensers at different heights of the column · CPC title

• F25J3/0295

  Start-up or control of the process; Details of the apparatus used, e.g. sieve plates, packings · CPC title