Treatment of spent caustic refinery effluents

• US 20040040671A1
• Filed: 09/04/2002
• Published: 03/04/2004
• Est. Priority Date: 09/04/2002
• Status: Active Grant

• Current Assignee: APTIM Liquid Solutions LLC (APTIM Corp.), GEI Liquid Solutions LLC
• Original Assignee: APTIM Liquid Solutions LLC (APTIM Corp.)
• Inventors: Rutsch, Michael J., Duesel, Bernard F. Jr., Gibbons, John P.
• Granted Patent: US 7,214,290 B2
• Time in Patent Office: Days
• US Class Current: 159/47.1
• CPC Class Codes: B01D 1/0058 Use of waste energy from other processes or sources, e.g. combustion gas for water treatment C02F1/16
• CPC Class Codes: B01D 1/14 with heated gases or vapours or liquids in contact with the liquid
• CPC Class Codes: B01D 21/0024 Inlets or outlets provided with regulating devices, e.g. valves, flaps B01D21/24 takes precedence
• CPC Class Codes: B01D 21/302 Active control mechanisms with external energy, e.g. with solenoid valve
• CPC Class Codes: B01D 21/34 Controlling the feed distribution; Controlling the liquid level ; Control of process parameters
• CPC Class Codes: C10G 19/08 Recovery of used refining agents

Abstract

In the methods for treatment of caustic effluents described in the specification, a spent caustic refinery effluent is supplied to a submerged combustion gas evaporator in which hot combustion gas containing carbon dioxide is injected into the caustic liquid to concentrate the liquid and convert a hydroxide constituent to a carbonate. Where the caustic effluent is from a petroleum refinery, oil in the waste liquid is separated from the aqueous constituent before, during or after concentration.

Claims

1. A method for treating spent caustic effluents comprising:

supplying a spent caustic effluent to a submerged combustion gas evaporator; and

supplying combustion gas to the submerged combustion gas evaporator at a temperature and quantity high enough to vaporize water and volatile constituents in the spent caustic effluent and concentrate a constituent of the spent caustic effluent.

2. A method according to claim 1 including thermally oxidizing vaporized constituents removed from the spent caustic effluent to eliminate odorous and other volatile materials from gaseous constituents released to the atmosphere.

3. A method according to claim 1 wherein the spent caustic effluent includes an aqueous caustic liquid and oil and including the step of separating at least some of the oil from the aqueous constituent in an immiscible liquid separator.

4. A method according to claim 3 wherein the immiscible liquid separator comprises at least one of a gravity settling tank, an inclined plate separator and a centrifuge.

5. A method according to claim 1 wherein the combustion gas supplied to the submerged combustion gas evaporator contains carbon dioxide and including the step of reacting the carbon dioxide with a caustic constituent of the spent caustic effluent to convert the caustic constituent to a carbonate, thereby sequestering carbon dioxide from the combustion gas.

6. A method according to claim 1 wherein the content of caustic material in the caustic waste liquid supplied to the combustion gas evaporator has a sodium hydroxide equivalency within a range from about one percent to about 50% by weight.

7. A method according to claim 1 including maintaining the spent caustic effluent in the submerged combustion gas evaporator at a level between about 5 inches and about 100 inches above the level at which the combustion gas is injected into the evaporator.

8. A method according to claim 1 including maintaining an operating pressure within the submerged combustion gas evaporator in a range from about 50 inches negative to about 100 inches positive of water.

9. A method according to claim 1 including supplying a fuel and air mixture at a pressure in a range from about 5 inches to about 200 inches of water to a burner to produce the combustion gas.

10. A method according to claim 1 including supplying a stack gas from a separate combustion process to the submerged combustion gas evaporator at a pressure in a range from about 60 inches negative to about 100 inches positive of water.

11. A method according to claim 1 including maintaining an operating temperature within the submerged combustion gas evaporator within a range from about 1000 F to about 250°

F.

12. A method according to claim 1 wherein the spent caustic effluent contains oil and including the step of removing at least some oil from the caustic waste liquid before supplying the caustic waste liquid to the submerged combustion gas evaporator.

13. A method according to claim 1 including supplying a sulfidic spent caustic effluent to the submerged combustion gas evaporator.

14. A method according to claim 1 including supplying a cresylic spent caustic effluent to the submerged combustion gas evaporator.

15. A method according to claim 1 including supplying a napthenic spent caustic effluent to the combustion gas evaporator.

16. A method according to claim 1 including supplying any combination of sulfidic, cresylic and napthenic spent caustic effluents to the combustion gas evaporator.

17. A method according to claim 1 including sequestering at least some carbon dioxide from the combustion gas by converting a caustic effluent constituent from a hydroxide to a carbonate.

18. A method according to claim 1 including stripping at least some volatile compounds from the spent caustic effluent in an air stripper prior to supplying the spent caustic effluent to the evaporator and supplying air from the air stripper containing volatile compounds to a burner used to produce the combustion gas.

19. A method for treating caustic materials comprising supplying a caustic solution which has a sodium hydroxide equivalency in a range from about one percent to about 50 percent to a submerged combustion gas evaporator and supplying combustion gas which contains carbon dioxide to the combustion gas evaporator and wherein the carbon dioxide reacts with the waste liquid to convert a hydroxide constituent thereof to a carbonate, thereby sequestering carbon dioxide from the combustion gas.