Abstract: There is provided an acid gas absorbent having excellent performance of absorbing acid gas such as carbon dioxide, and an acid gas removal device and an acid gas removal method using the acid gas absorbent. An acid gas absorbent of an embodiment contains at least one type of tertiary amine compound represented by the following general formula (1). (In the above formula (1), the cycle A represents acyclic structure whose carbon number is not less than 3 nor more than 8. R1, R2 and R3 each represent an alkyl group whose carbon number is 1 to 4, and R4 represents a hydroxyalkyl group. R1 and R2 are groups coupled to carbon atoms adjacent to a carbon atom forming the cycle A and coupled to a nitrogen atom.

Abstract: In one embodiment, an amine capturing system includes a carbon dioxide capturing module configured to bring a gas containing carbon dioxide in contact with an absorbing solution containing amine to cause the absorbing solution to absorb the carbon dioxide. The system further includes a first cleaning apparatus configured to clean the gas exhausted from the carbon dioxide capturing module with a cleaning liquid to capture the amine entrained by the gas, and a second cleaning apparatus configured to clean the gas exhausted from the first cleaning apparatus with a cleaning liquid to capture the amine entrained by the gas. The system is configured to measure a concentration of the amine in the cleaning liquid used in the second cleaning apparatus, and send the cleaning liquid used in the second cleaning apparatus to the first cleaning apparatus when the detected concentration exceeds a predetermined value.

Abstract: In one embodiment, a carbon dioxide separating and recovering system includes an absorption tower to cause carbon dioxide to be absorbed in an absorbing solution, a regeneration tower to release the carbon dioxide from the absorbing solution, and at least one measuring apparatus to measure an ultrasound propagation speed in the absorbing solution. Each of the at least one measuring apparatus calculates a dissolved carbon dioxide concentration in the adsorbing solution, based on a temperature measured by a temperature measuring unit, the ultrasound propagation speed measured by an ultrasound propagation speed measuring unit, and a correlation expression which shows a relationship between the dissolved carbon dioxide concentration and the ultrasound propagation speed in the absorbing solution, and is changed according to the temperature of the absorbing solution.

Abstract: Disclosed is a measurement device with which it is possible to quickly measure the carbon dioxide content of an absorbent solution circulating through a carbon dioxide recovery system.