A CO 2 recovery apparatus according to a first embodiment of the present invention includes: a CO 2 absorber that brings flue gas containing CO 2 into contact with CO 2 absorbing liquid to reduce CO 2 in the flue gas; a regenerator that reduces CO 2 in CO 2 absorbing liquid (rich solvent) that has absorbed the CO 2 in the CO 2 absorber to regenerate the CO 2 absorbing liquid, so that the regenerated absorbing liquid (lean solvent), having CO 2 reduced in the regenerator, is reused in the CO 2 absorber; a first compressor to a fourth compressor that compress the CO 2 gas released from the regenerator; and an O 2 reducing apparatus arranged between the second compressor and a second cooler to reduce O 2 in the CO 2 gas.
1. A CO 2 recovery apparatus comprising:
a CO 2 absorber that brings flue gas containing CO 2 into contact with CO 2 absorbing liquid to reduce CO 2 in the flue gas;
a regenerator that reduces CO 2 in rich solvent that has absorbed CO 2 in the CO 2 absorber, so that lean solvent having CO 2 reduced by the regenerator is reused in the CO 2 absorber;
at least two compressors that compress CO 2 gas released from the regenerator; and
an oxygen reducing apparatus that reduces O 2 in the CO 2 gas and is arranged between a first separator arranged downstream of a first compressor and a second separator arranged downstream of a second compressor.
2. The CO 2 recovery apparatus according to claim 1 , wherein the oxygen reducing apparatus is arranged between the second compressor and a second cooler that is arranged downstream of the second compressor and upstream of the second separator.
3. The CO 2 recovery apparatus according to claim 1 , wherein the oxygen reducing apparatus includes a combustion catalyst that reduces O 2 in the CO 2 gas.
4. The CO 2 recovery apparatus according to claim 3 , wherein the oxygen reducing apparatus includes the combustion catalyst, and is structured as a cartridge that is configured to be assembled into a pipe for supplying compressed CO 2 gas, a static mixer or a honeycomb having a surface thereof applied with the combustion catalyst, or a packed bed packed with granular catalysts having a pellet or spherical shape.
5. The CO 2 recovery apparatus according to claim 3 , wherein the combustion catalyst is a Pd-based or Pt-based metal catalyst.
6. The CO 2 recovery apparatus according to claim 3 , wherein the oxygen reducing apparatus includes a hydrogen gas supplying unit that supplies hydrogen-rich gas.
7. The CO 2 recovery apparatus according to claim 6 , wherein the hydrogen-rich gas is hydrogen produced by a hydrogen producing apparatus performing a reforming process and a CO shifting process and using a fossil fuel as a raw material.
8. The CO 2 recovery apparatus according to claim 6 , wherein the hydrogen-rich gas contains CO in addition to hydrogen.
9. The CO 2 recovery apparatus according to claim 1 , wherein the hydrogen gas supplying unit is arranged upstream of a compressor that is arranged upstream of the oxygen reducing apparatus.
10. A CO 2 recovery method comprising recovering CO 2 using the CO 2 recovery apparatus according to claim 1 , while reducing oxygen concentration in the CO 2 gas recovered from the regenerator at a process of compressing the CO 2 gas.