CO2 RECOVERY SYSTEM AND CO2 RECOVERY METHOD

• US 20140248206A1
• Filed: 03/04/2013
• Published: 09/04/2014
• Est. Priority Date: 03/04/2013
• Status: Active Grant

• Current Assignee: Mitsubishi Heavy Industries Engineering, Ltd. (Mitsubishi Heavy Industries, Ltd.)
• Original Assignee: Mitsubishi Heavy Industries, Ltd.
• Inventors: Tsujiuchi, Tatsuya, Yonekawa, Takahito, Honjo, Shintaro, Inui, Masayuki, Nakayama, Koji, Kamijo, Takashi, Nagayasu, Hiromitsu
• Granted Patent: US 9,623,366 B2
• Time in Patent Office: Days
• US Class Current: 423/437.1
• 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 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/68 Halogens or halogen compounds
• CPC Class Codes: B01D 53/72 Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons
• CPC Class Codes: C02F 1/20 by degassing, i.e. liberation of dissolved gases degasification of liquids in general B01D19/00; arrangement of degassing apparatus in boiler feed supply F22D
• CPC Class Codes: C02F 1/42 by ion-exchange ion-exchange in general B01J
• CPC Class Codes: C02F 1/5236 using inorganic agents
• CPC Class Codes: C02F 2101/106 Selenium compounds
• CPC Class Codes: C02F 2103/08 Seawater, e.g. for desalination
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A CO₂ recovery system includes an absorption apparatus that brings a CO₂ absorption liquid into contact with an exhaust gas treated by a pre-treatment apparatus so that CO₂ in the exhaust gas is absorbed into the CO₂ absorption liquid; a regeneration apparatus that separates CO₂ from the CO₂ absorption liquid; an absorption liquid circulation path that circulates the CO₂ absorption liquid between the absorption apparatus and the regeneration apparatus; and an impurity removal unit that removes impurities having a high concentration in the absorption liquid circulation path, in the absorption liquid circulation path and/or in the pre-treatment apparatus in advance.

Claims

1. A CO₂ recovery system comprising:

a pre-treatment apparatus that cools an exhaust gas;

an absorption apparatus that brings a CO₂ absorption liquid into contact with the exhaust gas treated by the pre-treatment apparatus so that CO₂ in the exhaust gas is absorbed into the CO₂ absorption liquid;

a regeneration apparatus that receives the CO₂ absorption liquid having absorbed CO₂ from the absorption apparatus and heats the CO₂ absorption liquid to separate CO₂ from the CO₂ absorption liquid;

an absorption liquid circulation path that circulates the CO₂ absorption liquid between the absorption apparatus and the regeneration apparatus; and

an impurity removal unit that removes impurities dissolved in the CO₂ absorption liquid and having a high concentration in the absorption liquid circulation path from the exhaust gas, in the absorption liquid circulation path and/or in the pre-treatment apparatus in advance.

2. The CO₂ recovery system according to claim 1, wherein:

the impurities are substances containing at least one kind of selenium, arsenic, cadmium, lead, hexavalent chromium, mercury, copper, fluorine, and boron.

3. The CO₂ recovery system according to claim 1, wherein:

the impurity removal unit includes an electrostatic precipitator provided in the pre-treatment apparatus.

4. The CO₂ recovery system according to claim 1, wherein:

the impurity removal unit includes an impurity removal demister provided in the pre-treatment apparatus and/or the absorption apparatus.

5. The CO₂ recovery system according to claim 1, wherein:

the pre-treatment apparatus includes a scrubber, and

the impurity removal unit includes an exhaust water treatment apparatus that treats washing water sprayed from the scrubber of the pre-treatment apparatus to remove impurities contained in the washing water.

6. The CO₂ recovery system according to claim 1, wherein:

the impurity removal unit includes a filtering apparatus that filters the CO₂ absorption liquid supplied from the absorption apparatus to the regeneration apparatus of the absorption liquid circulation path and/or the CO₂ absorption liquid supplied from the regeneration apparatus to the absorption apparatus of the absorption liquid circulation path to remove the impurities.

7. The CO₂ recovery system according to claim 1, wherein:

the absorption apparatus includes a scrubber, and

the impurity removal unit includes a filtering apparatus that filters the washing water sprayed by the scrubber of the absorption apparatus to remove impurities contained in the washing water, and returns the filtered washing water to a washing water circulation path and/or the absorption liquid circulation path of the scrubber of the absorption apparatus.

8. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

an ion-exchange apparatus that brings the CO₂ absorption liquid supplied from the absorption apparatus to the regeneration apparatus of the absorption liquid circulation path and/or the CO₂ absorption liquid supplied from the regeneration apparatus to the absorption apparatus of the absorption liquid circulation path into contact with an ion-exchange resin to remove the impurities.

9. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus; and

an ion-exchange apparatus that brings the CO₂ absorption liquid of an absorption liquid drawing path that supplies the CO₂ absorption liquid from the absorption liquid circulation path to the reclaimer into contact with an ion-exchange resin to remove the impurities.

10. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus; and

a coagulation sedimentation treatment apparatus that coagulates and sediments the CO₂ absorption liquid of an absorption liquid drawing path that supplies the CO₂ absorption liquid from the absorption liquid circulation path to the reclaimer, to remove the impurities.

11. The CO₂ recovery system according to claim 10, wherein:

the coagulation sedimentation treatment apparatus adjusts pH of the CO₂ absorption liquid using CO₂ separated in the regeneration apparatus.

12. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus; and

an incinerator that incinerates concentrated residue generated from the reclaimer,

wherein steam is generated using exhaust heat when the concentrated residue is incinerated in the incinerator, and the steam is used in the reclaimer and/or the regeneration apparatus.

13. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus; and

an ion-exchange apparatus that brings concentrated residue generated from the reclaimer into contact with an ion-exchange resin to remove the impurities.

14. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus; and

a coagulation sedimentation treatment apparatus that coagulates and sediments concentrated residue generated from the reclaimer to remove the impurities.

15. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus; and

an electrodialysis treatment apparatus that performs electrodialysis on concentrated residue generated from the reclaimer to remove the impurities.

16. The CO₂ recovery system according to claim 15, wherein:

the pre-treatment apparatus includes a scrubber, and

acidic treated water generated by treatment in the electrodialysis treatment apparatus of the impurity removal unit is supplied as cleaning water for acid cleaning of the scrubber of the pre-treatment apparatus.

17. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a first reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus; and

a second reclaimer that heats concentrated residue generated from the first reclaimer, further heats and concentrates the concentrated residue, and returns condensate water to the regeneration apparatus.

18. The CO₂ recovery system according to claim 17, wherein:

NaOH is added to the concentrated residue at the time of treatment in the second reclaimer of the impurity removal unit.

19. The CO₂ recovery system according to claim 17, wherein the impurity removal unit comprises:

a vacuum reclaiming path disposed by connecting a condenser, a gas and liquid separation apparatus, and a vacuum fan in series with the second reclaimer.

20. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a first reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus;

a condensate water return path that returns condensate water separated in the first reclaimer to the regeneration apparatus; and

a vacuum reclaiming path disposed by connecting a condenser, a gas and liquid separation apparatus, and a vacuum fan in series with the first reclaimer.

21. The CO₂ recovery system according to claim 1, wherein the impurity removal unit comprises:

a first reclaimer that draws and heats the CO₂ absorption liquid of the absorption liquid circulation path, heats and concentrates impurities in the CO₂ absorption liquid, and returns condensate water to the regeneration apparatus;

an evaporation and concentration apparatus that heats concentrated residue generated from the first reclaimer to generate steam, and heats and concentrates the concentrated residue; and

a gas and liquid separation apparatus that separates the steam generated from the evaporation and concentration apparatus into a gas and condensate water, and returns the gas to the pre-treatment apparatus and the condensate water to the absorption apparatus.

22. A CO₂ recovery method comprising:

cooling an exhaust gas by a pre-treatment apparatus;

bringing, by an absorption apparatus, the exhaust gas treated by the pre-treatment apparatus into contact with a CO₂ absorption liquid so that CO₂ in the exhaust gas is absorbed into the CO₂ absorption liquid;

receiving the CO₂ absorption liquid treated in the absorption apparatus and heating, by a regeneration apparatus, the CO₂ absorption liquid to separate CO₂ from the CO₂ absorption liquid;

circulating the CO₂ absorption liquid between the absorption apparatus and the regeneration apparatus through an absorption liquid circulation path to perform removal of CO₂ and recovery of CO₂ from the exhaust gas; and

removing, by an impurity removal unit, impurities dissolved in the CO₂ absorption liquid and having a high concentration in the absorption liquid circulation path from the exhaust gas, in the absorption liquid circulation path and/or in the pre-treatment apparatus in advance.