关键词: 烟气CO₂捕集, 非水吸收剂, 含水量, 腐蚀性, 缓蚀剂

Abstract:

The carbon dioxide (CO₂) capture technology using traditional absorbent of organic amine aqueous solution from flue gas is well-established and has significant potential for large-scale application. However, the post-absorption solution exhibits corrosive properties, which can severely reduce the service life of equipment and pipelines. Non-aqueous absorbents containing amines not only have the same advantages of faster CO₂ absorption rate and higher capacity as the traditional organic amine aqueous solution, but also have a minimal corrosivity toward metal equipment. But in fact, water vapor absorbed during the CO₂ capture process from flue gas can alter corrosion characteristics of non-aqueous absorbent. Thus, this study investigated the influence of varying water content in the monoethanolamine-N,N-dimethylformamide (MEA-DMF) non-aqueous absorbent on the corrosion behavior of carbon steel during CO₂ capture process from flue gas, and proposed effective corrosion inhibition strategies. The results showed that MEA-DMF non-aqueous absorbent was non-corrosive to carbon steel. With the number of absorption-desorption cycles increased, the water content in the absorbent gradually rose, leading to the enhancement of corrosion towards carbon steel. EDS analysis confirmed that the corrosion mechanism was consistent with that of wet CO₂ and amine solution. Additionally, the corrosiveness intensified with increasing temperature and CO₂ load once water was present in the absorbent. In order to alleviate the corrosiveness, it was necessary to reducing the water content or adding >0.2g/L 2-mercaptobenzimidazole (MBI) corrosion inhibitor in absorbent, which could greatly mitigate the corrosivity of the MEA-DMF absorbent towards carbon steel during the wet flue gas CO₂ capture process.

Key words: flue gas CO₂ capture, non-aqueous absorbent, water content, corrosiveness, corrosion inhibitor