Co2 recovery device and method for cleaning filtration membrane device of co2 recovery device

Patent metadata

Field	Value
Publication number	US-2016121260-A1
Application number	US-201514893342-A
Country	US
Kind code	A1
Filing date	Feb 2, 2015
Priority date	Feb 5, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

A filtration membrane device which uses a filter to collect solid contents remaining in a branched lean solution cleans the filter by using a low-concentration CO 2 absorption liquid circulating within the system as cleaning water (containing the absorption liquid); rough cleaning, which returns the low-concentration CO 2 absorption liquid used for cleaning to a lean solution supply line, is performed; the filter is finish-cleaned by cleaning water from outside the system which does not include the CO 2 absorption liquid; the CO 2 absorption liquid which is adhered to the solid contents is washed and removed; finish-cleaning water which includes the CO 2 absorption liquid is returned to the lean solution supply line the moisture content within the system is maintained at a prescribed value by adjusting the water balance in an absorption tower and the concentration of the CO 2 absorption liquid which circulates within the system is kept at a prescribed concentration.

First claim

1 . A CO 2 recovery device comprising:
an absorption tower which brings an exhaust gas containing CO 2 into contact with a CO 2 absorption liquid to remove CO 2 ; an absorption liquid regeneration tower which regenerates a rich solution, which has absorbed CO 2 , through heat exchange; a rich solution supply line through which the rich solution is extracted from the absorption tower and is introduced into the absorption liquid regeneration tower side; a lean solution supply line through which a lean solution into which CO 2 regenerated in the absorption liquid regeneration tower has been emitted is extracted from the absorption liquid regeneration tower, and is introduced into the absorption tower, and the lean solution is reused as the CO 2 absorption liquid in the absorption tower; and a filtration membrane device which is interposed in a lean solution branch line branched from the lean solution supply line, the rich solution supply line, or both the solution supply lines, collects solid contents remaining in the branched solution using a filter, and returns filtrate, which has passed through the filter, to the solution supply line, wherein, with respect to the filtration membrane device when the filter has been used to collect the solid contents, the filter is cleaned using a low-concentration CO 2 absorption liquid as cleaning water, the low-concentration CO 2 absorption liquid circulating within a system; rough cleaning, which returns the low-concentration CO 2 absorption liquid used for cleaning to the solution supply line, is performed; the filter is finish-cleaned by cleaning water which does not include the CO 2 absorption liquid and which is from outside the system; the CO 2 absorption liquid which is adhered to the collected solid contents is cleaned and removed; finish-cleaning water which includes the CO 2 absorption liquid is returned to the solution supply line; the moisture content within the system is maintained at a prescribed value by adjusting the water balance within the absorption tower; and the concentration of the CO 2 absorption liquid which circulates within the system is kept at a prescribed concentration.

2 . The CO 2 recovery device according to claim 1 ,
wherein the water balance within the absorption tower is adjusted by controlling the temperature of the cleaning water in a cleaning section.

3 . The CO 2 recovery device according to claim 1 ,
wherein the water balance in the absorption tower is adjusted by controlling the temperature of cooling water in a cooling tower which cools the exhaust gas containing CO 2 before being introduced into the absorption tower.

4 . The CO 2 recovery device according to claim 1 ,
wherein the absorption liquid regeneration tower includes a separation drum which condenses steam in emission gas containing CO 2 gas that has entrained the steam discharged from a top of the absorption liquid regeneration tower, and separates water, wherein the absorption tower includes: a CO 2 recovery section which brings the exhaust gas containing CO 2 into contact with the CO 2 absorption liquid to absorb CO 2 in the exhaust gas; at least one or more cleaning sections which are disposed on an upper stage side of the CO 2 recovery section, cool CO 2 -removed exhaust gas from which CO 2 has been removed, and recover an entrained CO 2 absorption liquid using the cleaning water; and a condensed water receiving section which is disposed on a lower side of each of the cleaning sections, and recovers condensed water within the cleaning section, and wherein a low-concentration CO 2 absorption liquid in any one or both of the condensed water recovered in the condensed water receiving section of the absorption tower and the water separated in the separation drum is used as the cleaning water of the rough cleaning.

5 . The CO 2 recovery device according to claim 1 ,
wherein the solid contents collected by the filter are removed by performing reverse washing using gas or a cleaning liquid supplied from the outside of the system.

6 . The CO 2 recovery device according to claim 1 ,
wherein at least two systems of the filters are provided, and the solid contents in the CO2 absorption liquid are alternately collected.

7 . The CO 2 recovery device according to claim 1 ,
wherein the CO2 absorption liquid is an amine-based absorption liquid.

8 . A method for cleaning a filtration membrane device of a CO 2 recovery device which regenerates a rich solution, which has absorbed CO 2 , in a regeneration tower after CO 2 is removed by bringing an exhaust gas containing CO2 into contact with a CO 2 absorption liquid within a CO 2 recovery section of an absorption tower and which filters solid contents remaining in a lean solution, from which the regenerated CO 2 has been removed, using a filter provided in a filtration membrane device, the method comprising:
supplying a low-concentration CO 2 absorption liquid circulating within a system to the filtration membrane device, rough-cleaning the filter using the low-concentration CO 2 absorption liquid, returning the low-concentration CO 2 absorption liquid, which has cleaned the filter, again to the system, finish-cleaning the filter using a cleaning liquid which does not include the CO 2 absorption liquid from the outside of the system, and returning the low-concentration CO 2 absorption liquid, which has cleaned the filter, again to the inside of the system; and thereafter, adjusting the content of moisture increased by supplying cleaning water from the outside of the system, and maintaining a balance of the water circulating within the system.

9 . The method for cleaning a filtration membrane device of a CO 2 recovery device according to claim 8 ,
wherein a low-concentration CO 2 absorption liquid in any one or both of condensed water recovered in a condensed water receiving section of the absorption tower and water separated in a separation drum is used as the cleaning water.

10 . The method for cleaning a filtration membrane device of a CO 2 recovery device according to claim 8 ,
wherein the CO 2 absorption liquid is an amine-based absorption liquid.

11 . The method for cleaning a filtration membrane device of a CO 2 recovery device according to claim 8 ,
wherein the water balance within the absorption tower is adjusted by controlling the temperature of the cleaning water in the cleaning section.

12 . The method for cleaning a filtration membrane device of a CO 2 recovery device according to claim 8 ,
wherein the water balance in the absorption tower is adjusted by controlling the temperature of cooling water in a cooling tower which cools the exhaust gas containing CO 2 before being introduced into the absorption tower.

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Hirata Takuya
• Nagayasu Hiromitsu
• Tanaka Hiroshi
• Noborisato Tomoki
• Oishi Tsuyoshi

Classifications

• B01D2252/103

  Water · CPC title

• B01D65/02

  Membrane cleaning or sterilisation {; Membrane regeneration} · CPC title

• B01D2257/504

  Carbon dioxide · CPC title

• B01D53/1475

  Removing carbon dioxide · CPC title

• B01D53/1425 Primary

  Regeneration of liquid absorbents · CPC title