The role of direct contact condenser in fine-tuning aqueous Ammonia PCC

Solvent-based aqueous ammonia post-combustion carbon capture (PCC) is a well-recognized and leading technology for CO2 emissions reduction from coal-fired power stations. With many techno-economic advantages of this technology over counterparts, a few major challenges may still prevent this technology from large-scale adoption. This study analyses the real-time data obtained from our pilot-plant operation at Vales Point coal-fired power station and evaluates the functionality of the direct contact condenser (DCC) in the wash and the stripper columns. It is found that the DCC can effectively eliminate ammonia and water slips in wash column by 86% and 38%, respectively, and greatly mitigate the temperature at the stripper overhead. This has some benefits in enhancing the product CO2 purity and lowering the reboiler/condenser duties. In this context, this study proposed another compact size DCC to replace the typical bulky condenser at the stripper overhead. It was found that a new combined circuit DCC can better enhance the CO2 product purity, bringing its temperature to the nominal target, and produce less and diluted condensate that is easier for downstream integration. Most importantly, this configuration can effectively eliminate the ammonia slip in the CO2 product line and solid precipitation at the stripper overhead. Validating these improvements at our current pilot-plant would facilitate the commercialization of this promising technology.