Reduction of Amine Loss during CO_2 Recovery from Exhaust Gas of Fossi Fuel-Fired Power Plant by Chemical Absorption Method

摘要

Carbon dioxide removal was carraied out for LNG-fired powder station flue gas, using a pilot-scale absorber of about 25 m in height at an exhaust gas flow rat of 555 m~3/h. The relationship betweem amine loss discharged from a CO_2 recovery system and the operating conditions and configuration of the washing water line equipped with an absorber unit were examined. The test result showed that outlet alkali (amine) concentration was confirmed to decrease with decreasing absorber outlet temperature. The alkali concentration was confirmed to decreae with a decrease in the alkali concentration in washing water. An improvement of washing water line by dividing it into two steps was found to be remarkably effective to decrease outlet alkali concentration. In the case of KS-1 solution, which is composed of sterically hindered amine and alkanolamine, excellent results were obtained by such a strategy to reduce amine loss: outlet alkali concentration ranged from 2.3 ppm to 10.4 ppm, and average amine loss amounted ot 0.11 g-amine/KGCO_2. This degree of amine loss is as low as 1/20th of that of the conventinal process. Both a low impact on the environment and a reasonable cost reduction can be attained by adopting a two-step washing water line.