CO2 recovery unit and method therefor

1. A CO 2 recovery unit including a CO 2 absorber that brings flue gas containing CO 2 into contact with a CO 2 absorbent and removes CO 2 in the flue gas, and a regenerator that diffuses CO 2 in a rich solution having absorbed CO 2 in the CO 2 absorber, to reuse in the CO 2 absorber a lean solution which is obtained by removing CO 2 from the rich solution in the regenerator, comprising:

at least two compressors that compress CO 2 gas discharged from the regenerator;

a dehydrating column that is provided between any two of the compressors and reduces moisture in the CO 2 gas by bringing the CO 2 gas into contact with a dehydrating agent;

a combustion removal unit that removes the dehydrating agent mixed in with CO 2 gas in the dehydrating column; and

a heat exchanger that is provided between the dehydrating column and the combustion removal unit and performs heat exchange between CO 2 gas discharged from any one of the compressors and CO 2 gas discharged from the dehydrating column.

2. The CO 2 recovery unit according to claim 1 , wherein the combustion removal unit is provided between the dehydrating column and a gas-liquid separator provided on a downstream side of the dehydrating column.

3. The CO 2 recovery unit according to claim 1 , wherein the combustion removal unit includes a combustion catalyst for removing a dehydrating agent in the CO 2 gas.

4. The CO 2 recovery unit according to claim 3 , wherein the combustion catalyst is a Pd metal catalyst or a Pt metal catalyst.

5. The CO 2 recovery unit according to claim 1 , comprising a branch passage for extracting CO 2 gas discharged from the combustion removal unit and merging the CO 2 gas with CO 2 gas discharged from the dehydrating column.

6. The CO 2 recovery unit according to claim 1 , comprising a hydrogen-gas supply unit that supplies hydrogen rich gas into the combustion removal unit.

7. The CO 2 recovery unit according to claim 6 , wherein the hydrogen rich gas is hydrogen produced by a hydrogen producing device, which uses fossil fuel as a raw material and has a reforming process and a CO shifting process.

8. The CO 2 recovery unit according to claim 6 , wherein the hydrogen rich gas contains CO as well as hydrogen.

9. A CO 2 recovery method of using the CO 2 recovery unit according to claim 1 , wherein in a process of compressing the CO 2 gas recovered from the regenerator, after moisture in the CO 2 gas is reduced by bringing the CO 2 gas into contact with the dehydrating agent, CO 2 gas after removal of moisture is heat-exchanged with CO 2 gas discharged from any one of compressors, and the dehydrating agent mixed in the CO 2 gas is removed by combustion and O 2 is removed, to recover CO 2 gas.

10. A CO 2 recovery unit including a CO 2 absorber that brings flue gas containing CO 2 into contact with a CO 2 absorbent and removes CO 2 in the flue gas, and a regenerator that diffuses CO 2 in a rich solution having absorbed CO 2 in the CO 2 absorber, to reuse in the CO 2 absorber a lean solution which is obtained by removing CO 2 from the rich solution in the regenerator, comprising:

at least two compressors that compress CO 2 gas discharged from the regenerator;

a dehydrating column that is provided between any two of the compressors and reduces moisture in the CO 2 gas by bringing the CO 2 gas into contact with a dehydrating agent;

a combustion removal unit that removes the dehydrating agent mixed in with CO 2 gas in the dehydrating column; and

a heat exchanger that is provided in the combustion removal unit and performs heat exchange between CO 2 gas discharged from any one of the compressors and CO 2 gas discharged from the dehydrating column.

11. The CO 2 recovery unit according to claim 10 , wherein the combustion removal unit includes a combustion catalyst for removing a dehydrating agent in the CO 2 gas, in which the heat exchanger and the combustion catalyst are arranged in this order from an inlet side of CO 2 gas into the combustion removal unit toward an outlet side thereof.

12. A CO 2 recovery method in which flue gas containing CO 2 is brought into contact with a CO 2 absorbent in a CO 2 absorber to remove CO 2 in the flue gas, CO 2 in a rich solution having absorbed CO 2 is removed in a regenerator, and a regenerated lean solution is reused in the CO 2 absorber, and CO 2 gas discharged from the regenerator is recovered, comprising:

compressing the CO 2 gas recovered from the regenerator by using at least two compressors;

reducing moisture in the CO 2 gas by bringing the CO 2 gas into contact with a dehydrating agent between any two of the compressors;

heat-exchanging CO 2 gas brought into contact with the dehydrating agent with CO 2 gas discharged from any one of the compressors; and

removing the dehydrating agent mixed in the CO 2 gas by combustion and removing 0 2 to recover CO 2 gas.

13. The CO 2 recovery method according to claim 12 , further comprising:

separating moisture in the CO 2 gas after removing the dehydrating agent.

14. The CO 2 recovery method according to claim 12 , wherein hydrogen rich gas is supplied at a time of combusting and removing the dehydrating agent mixed in the CO 2 gas.

15. The CO 2 recovery method according to claim 14 , wherein hydrogen produced by a hydrogen producing device, which uses fossil fuel as a raw material and has a reforming process and a CO shifting process, is used as the hydrogen rich gas.

16. The CO 2 recovery method according to claim 14 , wherein a gas containing CO as well as hydrogen is used as the hydrogen rich gas.