Cyclone separation and recovery of carbon dioxide from heated liquid absorbent

Patent metadata

Field	Value
Publication number	US-9861910-B2
Application number	US-201414572267-A
Country	US
Kind code	B2
Filing date	Dec 16, 2014
Priority date	Dec 16, 2014
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A process and system for improving the efficiency of regenerating a CO 2 -rich liquid absorbent stream following contact in an absorption zone with, e.g., a flue gas stream from which it has absorbed CO 2 , and recovering a substantially pure stream of includes passing the pressurized liquid sorbent through a heating zone to heat it to the desorption temperature, e.g., to about 80°-85° C. for aqueous K 2 CO 3 sorbent, introducing the heated liquid sorbent into a cyclone separation zone where the combination of increased temperature, reduced pressure and the centrifugal forces on the liquid/gas mixture result in a relatively more rapid and efficient separation of the CO 2 from the liquid sorbent from which it has been released. The CO 2 -lean liquid sorbent descends to the bottom of the cyclone separator and is recovered, cooled and recycled to the absorption zone; the CO 2 withdrawn from the cyclone separation zone passes through a condenser to remove moisture and any other condensates present, and the CO 2 is recovered for storage or use in downstream processes.

First claim

The invention claimed is:

1. A process for the separation and recovery of carbon dioxide from a CO 2 -rich liquid sorbent stream derived from a CO 2 absorption unit, the process comprising:
a. increasing the temperature of the CO 2 -rich liquid sorbent from the CO 2 sorption temperature to a predetermined desorption temperature by passing the stream in a conduit under pressure through a heating zone ( 30 );
b. passing the heated pressurized CO 2 -rich liquid sorbent from the heating zone through a sorbent conduit in a generally linear flow path;
c. introducing the heated CO 2 -rich liquid sorbent stream from the sorbent conduit ( 42 ) into an entry portion ( 43 a ) of a cyclonic member ( 43 ) under reduced pressure to initiate the desorption of CO 2 from the CO 2 -rich liquid sorbent and thereafter passing the liquid sorbent stream into a spiral section ( 43 b ) of the cyclonic member ( 43 ) which terminates in a decreasing radius of curvature while maintaining a non-turbulent flow of the liquid sorbent;
d. passing the liquid sorbent and desorbed CO 2 through an inlet ( 45 ) into an upper section of a closed cylindrical cyclonic vertical section ( 47 );
e. recovering CO 2 desorbed from the sorbent in a central open region of the cyclonic vertical section ( 47 ) and passing the CO 2 through a CO 2 discharge riser outlet ( 44 ) conduit that is in fluid communication with the upper region of the cyclonic vertical section;
f. recovering at the base of the cyclonic vertical section a CO 2 -lean liquid sorbent stream from which the CO 2 was desorbed from a horizontal section 48 of cyclonic vertical section ( 47 ); and
g. recycling the CO 2 -lean sorbent stream to the CO 2 absorption unit.

2. The process of claim 1 which includes
h. passing the CO 2 recovered from the riser outlet ( 44 ) to a condenser ( 70 ) in a condensing zone to separate from the CO 2 from any water vapor and other compounds desorbed from the liquid sorbent; and
i. recovering a substantially pure stream of CO 2 gas from the condensing zone.

3. The process of claim 1 in which the cyclonic vertical section ( 47 ) is of generally circular cross-section.

4. The process of claim 3 , in which diameter of the circular cross-section is uniform.

5. The process of claim 1 , where the cross-sectional area of the cyclonic member ( 43 ) increases over its length.

6. The process of claim 1 in which the cyclonic member ( 43 ) circumscribes an angle in the range of from 150° to 250° between the entry portion and the inlet ( 45 ) of the cyclonic vertical section ( 47 ).

7. The process of claim 1 in which the liquid sorbent follows a path of a descending spiral in the cyclonic member ( 43 ) proximate the inlet ( 45 ) before passing into the cyclonic vertical section ( 47 ).

8. The process of claim 1 in which the flow path of the cyclonic member ( 43 ) is comprised of arcuate sections having different diameters.

9. The process of claim 1 in which the CO 2 -lean sorbent recycle-stream from step 1 (g) is passed in heat exchange with the CO 2 -rich sorbent from the CO 2 desorption unit.

10. The process of claim 1 in which the liquid sorbent is an aqueous solution of K 2 CO 3 and the sorbent is heated in step 1 (a) to a temperature in the range from 80° C. to 85° C.

11. The process of claim 9 in which the temperature of the recycled CO 2 -lean sorbent is reduced to 40° C. or lower for return to the CO 2 adsorption unit.

Assignees

• Saudi Arabian Oil Co

Inventors

• Hammad Ahmad D
• Akhras Abdul Rahman Zafer
• Yusuf Zaki
• Rasheedi Nayif A
• Al-Qahtani Amjaad

Classifications

• B01D53/1425 Primary

  Regeneration of liquid absorbents · CPC title

• B01D53/1475

  Removing carbon dioxide · CPC title

• B01D19/0057 Primary

  the centrifugal movement being caused by a vortex, e.g. using a cyclone, or by a tangential inlet · CPC title

• B01D19/0068

  General arrangements, e.g. flowsheets (B01D19/0063 takes precedence) · CPC title

• Y02C10/06

  Cross-Sectional Technologies · mapped topic