Process for recovering processing liquids

• US 5,993,608 A
• Filed: 04/25/1997
• Issued: 11/30/1999
• Est. Priority Date: 04/25/1997
• Status: Expired due to Term

• Current Assignee: CCR Technologies Ltd.
• Original Assignee: Canadian Chemical Reclaiming Ltd.
• Inventors: Kresoyak, Stephen G., Carlson, Stephen W., Abry, Raymond G., Beasley, Todd S.
• Primary Examiner(s): Manoharan, Virginia
• Application Number:
  US08/846,036
• Time in Patent Office: 949 Days
• Field of Search: 203/1.4, 203/80, 203/77, 203/1, 203/40, 203/11, 203/90, 203/73, 203/2, 203/78, 203/20, 203/74-75, 203/100, 202/205, 202/236, 202/160, 202/237, 159/48.1, 159/DIG. 4, 159/44, 159/DIG. 16, 95/242-243, 95/251, 210/774, 564/497, 568/913, 568/868
• US Class Current: 203/11
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: Y10S 159/04 Foam
• CPC Class Codes: Y10S 159/16 Vacuum

Abstract

A process for recovering processing liquids such as gas-treating liquids wherein a feed mixture containing the processing liquid and components or impurities that are more volatile and less volatile than the processing liquid is initially heated in a first heating zone to a temperature sufficient to volatilize at least one of the more volatile components and a portion of the processing liquid, the temperature being maintained below the decomposition temperature of the processing liquid to produce a vapor stream containing the less volatile component and the vaporized portion of the processing liquid and a residuum containing the processing liquid, a reduced concentration of the more volatile components and the less volatile components, the vapor stream being separated from the residuum in a first separation zone, a portion of the residuum being passed through a second heating zone at a temperature below the decomposition temperature of the processing liquid to produce a first heated recycle stream, the heated recycle stream being admixed with the feed mixture to effect the initial heating of the feed mixture, the concentration of the less volatile components in the residuum being reduced, preferably on a continuous basis, any processing liquid present in the vapor stream being recovered for further use.

Claims

1. A continuous process for recovering a processing liquid from a feed mixture, comprising said processing liquid, at least one component that is more volatile than said processing liquid, and at least one component that is less volatile than said processing liquid, comprising:

introducing said feed mixture into a first heating zone and initially heating said feed mixture to a temperature sufficient to volatilize at least some of said at least one more volatile component and at least a portion of said processing liquid, said temperature in said first heating zone being below the decomposition temperature of said processing liquid, to produce a vapor stream comprising said at least one more volatile component and said vaporized portion of said processing liquid, and a residuum containing said processing liquid, a reduced concentration of said at least one more volatile component, and said at least one less volatile component;

separating said vapor stream from said residuum in a first separation zone to produce a separated residuum;

passing a first portion of said separated residuum through a second heating zone at a temperature below the decomposition temperature of said processing liquid to produce a heated, first recycle stream;

admixing said heated, first recycle stream with said feed mixture to effect said initial heating of said feed mixture;

passing a second portion of said separated residuum through a solids/liquid separation zone to remove any solids present in said second portion of said separated residuum and produce a substantially solids-free, second recycle stream, said second recycle stream being recycled to said first separation zone; and

recovering processing liquid from said vapor stream.

2. The process of claim 1 wherein said first separation zone includes an upper, substantially vapor phase zone and a lower, substantially liquid phase zone and wherein said second recycle stream is introduced into said vapor phase zone and sprayed downwardly toward the interface of said vapor phase zone and said liquid zone to control foaming in said first separation zone.

3. The process of claim 1 wherein said second heating zone comprises a tubular heating zone and said separated residuum is passed through said second heating zone at a flow rate of greater than 10 feet per second, the pressure inside the second heating zone being regulated by back pressure regulation to minimize vaporization in said second heating zone.

4. The process of claim 3 wherein said separated residuum is passed through said second heating zone at a flow rate of from about 11 to about 16 feet per second.

5. The process of claim 3 wherein said back pressure regulation is effected between said second heating zone and said first heating zone, said initial heating of said feed mixture and said separating in said first separation zone being conducted under vacuum conditions.

6. The process of claim 3 wherein said back pressure regulation is effected between said first heating zone and said first separation zone, said first heating zone being under positive pressure, said separating in said first separation zone being conducted under vacuum conditions.

7. The process of claim 1 wherein said feed mixture comprises from about 3 to about 30% by weight of said at least one less volatile component.

8. The process of claim 1 wherein said feed mixture comprises from about 10 ppm to about 60,000 ppm by weight of said less volatile component.

9. The process of claim 1 wherein said vapor stream contains a plurality of said more volatile components and said vapor stream is introduced into a second separation zone to recover processing liquid vaporized in said first separation zone.

10. The process of claim 1 wherein said feed mixture comprises water and a substantially clean water stream is recovered from said second separation zone.

11. The process of claim 1, wherein said any solids are initially present in said feed mixture.

12. The process of claim 1, wherein said any solids are formed from said less volatile component.

13. The process of claim 1, wherein said processing liquid comprises a gas scrubbing medium.

14. The process of claim 1, wherein said processing liquid is selected from the group consisting of alkanolamines containing from 1-8 carbon atoms, water soluble amines containing from 1-6 carbon atoms, water-miscible alcohols containing from 1-8 carbon atoms, glycols containing from 2-8 carbon atoms and mixtures thereof.

15. The process of claim 1 wherein said less volatile component comprises a liquid.