CARBON DIOXIDE RECOVERY APPARATUS AND CARBON DIOXIDE RECOVERY METHOD

• US 20150246313A1
• Filed: 12/08/2014
• Published: 09/03/2015
• Est. Priority Date: 02/28/2014
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: OGAWA, Takashi, MURAI, Shinji, MURAMATSU, Takehiko, SAITO, Satoshi
• Application Number:
  US14/563,098
• Publication Number:
  US 20150246313A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B01D 2252/20436 Cyclic amines
• CPC Class Codes: B01D 2252/20447 containing a piperazine-ring
• CPC Class Codes: B01D 2252/20484 with one hydroxyl group
• CPC Class Codes: B01D 2252/20489 with two or more hydroxyl groups
• CPC Class Codes: B01D 2252/602 Activators, promoting agents, catalytic agents or enzymes
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01D 53/78 with gas-liquid contact
• CPC Class Codes: B01D 53/96 Regeneration, reactivation or recycling of reactants
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

According to one embodiment, a CO₂ recovery apparatus 10 includes: an absorption tower 11 in which a lean solution 22 is allowed to absorb CO₂ in a discharge gas 21; a first heat exchange unit 12 in which a rich solution 23 is heated to from 50 to 100° C. to allow the rich solution 23 to have a mixed phase including two phases of a CO₂-rich phase 31 and a CO₂-lean phase 32; a phase separation unit 13 in which the rich solution 23 is separated into a CO₂-rich phase 31 and a CO₂-lean phase 32; and a regeneration tower 16 in which CO₂ contained In a separated CO₂-rich solution 46 including the CO₂-rich phase 31 is separated to regenerate the rich solution 23.

Claims

1. A carbon dioxide recovery apparatus comprising:

an absorption tower in which gas-liquid contact of a discharge gas containing CO₂ with an absorbing liquid is carried out to allow said absorbing liquid to absorb said CO₂;

a first heat exchange unit that heats said absorbing liquid containing CO₂ to from 50 to 100°

C. to allow said absorbing liquid containing CO₂ to have a mixed phase comprising a CO₂-rich phase and a CO₂-lean phase;

a phase separation unit that separates said absorbing liquid containing CO₂ into said CO₂-rich phase and said CO₂-lean phase, discharges said CO₂-rich phase as a separated CO₂-rich solution, and discharges said CO₂-lean phase as a separated CO₂-lean solution; and

a regeneration tower in which CO₂ contained in said separated CO₂-rich solution is separated to regenerate said absorbing liquid.

2. The apparatus according to claim 1, wherein said absorbing liquid comprises at least one amino group-containing compound that is reversibly changed to hydrophilicity or hydrophobicity depending on temperature and selected from the group consisting of amines.

3. The apparatus according to claim 1, wherein said phase separation unit comprises a filter comprising a fiber layer comprising a hydrophilic fiber, where said CO₂-lean phase is passed through said fiber layer, and a droplet contained in said CO₂-rich phase is trapped and allowed to be bulky by said fiber layer and then desorbed from said fiber layer;

and

said mixed phase passed through said fiber layer is separated into said CO₂-rich phase and said CO₂-lean phase due to a difference in specific gravity.

4. The apparatus according to claim 3, wherein said phase separation unit comprises:

a first filter to which said absorbing liquid containing CO₂ is supplied; and

a second filter through which said CO₂-lean phase passed through said first filter is passed.

5. The apparatus according to claim 1, further comprising a second heat exchange unit that heats said separated CO₂-rich solution using as a heat source said absorbing liquid regenerated in said regeneration tower.

6. The apparatus according to claim 1, further comprising a first mixing unit in which said absorbing liquid regenerated in said regeneration tower is mixed with said separated CO₂-lean solution.

7. The apparatus according to claim 6, wherein said first mixing unit is disposed between said absorption tower and said regeneration tower.

8. The apparatus according to claim 1, further comprising:

a cooling unit in which a CO₂ gas released from said phase separation unit is cooled;

a gas/liquid separation unit in which a condensate liquid contained in said cooled CO₂ gas is separated; and

a condensate liquid supply line through which said condensate liquid is supplied from said gas/liquid separation unit to said absorption tower.

9. A carbon dioxide recovery method comprising:

carrying out gas-liquid contact of a discharge gas containing CO₂ with an absorbing liquid to allow said absorbing liquid to absorb said CO₂ in an absorption tower;

heating said absorbing liquid containing CO₂ discharged from said absorption tower to from 50 to 100°

C. in a first heat exchange unit, followed by allowing said absorbing liquid containing CO₂ to have a mixed phase comprising a CO₂-rich phase and a CO₂-lean phase;

separating said absorbing liquid containing CO₂ into said CO₂-rich phase and said CO₂-lean phase in a phase separation unit;

discharging said CO₂-rich phase as a separated CO₂-rich solution;

discharging said CO₂-lean phase as a separated CO₂-lean solution;

supplying said separated CO₂-rich solution to a regeneration tower;

releasing CO₂ from said separated CO₂-rich solution to regenerate said absorbing liquid; and

supplying said absorbing liquid regenerated in said regeneration tower to said absorption tower.

10. The method according to claim 9, wherein said absorbing liquid comprises at least one amino group-containing compound that is reversibly changed to hydrophilicity or hydrophobicity depending on temperature and selected from the group consisting of amines.

11. The method according to claim 9, wherein said phase separation unit comprises a filter comprising a fiber layer comprising a hydrophilic fiber, where said CO₂-lean phase is passed through said fiber layer, and a droplet contained in said CO₂-rich phase is trapped and allowed to be bulky by said fiber layer and then desorbed from said fiber layer;

said mixed phase is allowed to pass through said fiber layer, whereby said droplet contained in said CO₂-rich phase is trapped and allowed to be bulky; and

said mixed phase passed through said fiber layer is separated into said CO₂-rich phase and said CO₂-lean phase due to a difference in specific gravity.

12. The method according to claim 9, wherein said phase separation unit comprises a first filter and a second filter, comprising a fiber layer comprising a hydrophilic fiber;

said CO₂-lean phase is passed through said first fiber layer of said first filter, and a droplet contained in said CO₂-rich phase is trapped and allowed to be bulky by said first fiber layer and then desorbed from said first fiber layer;

said CO₂-lean phase passed through said first filter is further passed through said second fiber layer of said second filter;

said mixed phase is passed through said first fiber layer, whereby said droplet contained in said. CO₂-rich phase is trapped and allowed to be bulky; and

said mixed phase passed through said first fiber layer is separated into said CO₂-rich phase and said CO₂-lean phase due to a difference in specific gravity, and said CO₂-lean phase is further passed through said second filter.

13. The method according to claim 9, wherein a CO₂-containing gas released from said phase separation unit is cooled, CO₂ contained in said CO₂-containing gas is then separated from a condensate liquid, and said separated condensate liquid is supplied to said absorption tower.

14. The method according to claim 9, wherein said separated CO₂-rich solution is heated using said absorbing liquid regenerated in said regeneration tower.

15. The method according to claim 9, wherein said separated CO₂-lean solution is mixed with said absorbing liquid regenerated in said regeneration tower and then supplied to said absorption tower.

16. The method according to claim 15, wherein said absorbing liquid regenerated in said regeneration tower is mixed with said separated CO₂-lean solution and then supplied to said first heat exchange unit, and said absorbing liquid containing CO₂ discharged from said absorption tower is heated.

17. The method according to claim 9, wherein a CO₂ gas released from said phase separation unit is cooled to separate a condensate liquid contained in said CO₂ gas, and said condensate liquid is supplied to said absorption tower.