Patent ID: 8702839

Claim:
A CO 2 recovery method, for a CO 2 absorber that brings flue gas containing CO 2 into contact with a CO 2 absorbent to reduce the CO 2 contained in the flue gas, and a regenerator that reduces CO 2 contained in rich solvent absorbing CO 2 in the CO 2 absorber to regenerate the rich solvent, so that lean solvent from which the CO 2 is reduced in the regenerator is reused in the CO 2 absorber, the method comprising the steps of: allowing the rich solvent to exchange heat with the lean solvent; and controlling to extract part of the rich solvent to allow the part to bypass the heat exchanger, and to be supplied into a top of the regenerator without exchanging heat so as to minimize a sum of an enthalpy (E1) that is taken out of the regenerator as CO 2 gas accompanying steam and an enthalpy (E2) that is a result of subtracting an enthalpy of the rich solvent before heat exchange in the heat exchanger from an enthalpy of the lean solvent after the heat exchange; characterized in that the controlling step includes adjusting the amount of the rich solvent to be split under an instruction of a controller by adjusting an adjusting valve provided on a split rich solvent supplying line based on information obtained by a plurality of sensors for detecting at least temperatures provided on a rich solvent supplying line and a lean solvent supplying line, respectively, and a flow meter provided on the split rich solvent supplying line upstream of the adjusting valve so as to approximate a temperature difference ΔTa between the rich solvent and the lean solvent at an entering side of the heat exchanger and a temperature difference ΔTG between the rich solvent and the lean solvent at an exiting side of the heat exchanger.