CO2 recovery system and CO2 recovery method

A CO2 recovery system comprising:

• an absorber including a CO2 absorbing section and at least one water-washing section, the CO2 absorbing section allowing flue gas to comes into contact with a basic amine compound absorbent so that the basic amine compound absorbent absorbs CO2 in the flue gas, the at least one water-washing section allowing the decarbonated flue gas in which an amount of CO2 has been reduced in the CO2 absorbing section to come into contact with wash water to reduce amounts of the basic amine compounds entrained in the decarbonated flue gas;
• a regenerator for releasing the CO2 from the basic amine compound absorbent containing the CO2 absorbed therein;
• an absorbent-treating section disposed downstream of the at least one water-washing section through which the decarbonated flue gas flows, the absorbent-treating section allowing the decarbonated flue gas to come into contact with circulating acidic water to further reduce the amounts of the basic amine compounds entrained in the decarbonated flue gas;
• an acidic water circulation pump for circulating the circulating acidic water;
• and
• a control unit for adjusting a pH value of the acidic water to a desired value by controlling a flow rate of the acidic water circulation pump for obtaining salts of the basic amine compounds by contact with the decarbonated flue gas.