Process enhancement in aqueous ammonia PCC using a direct contact condenser

Aqueous ammonia‐based post‐combustion carbon capture (PCC) is a well recognized and leading technology for the reduction of CO2 emissions from coal‐fired power stations. Despite its many techno‐economic advantages over its counterparts, there are still a few major challenges that could prevent its large‐scale adoption. This model‐based study addresses the most common problems of solid precipitation at the stripper overhead and ammonia slipping with the product CO2. We propose using a direct contact condenser (DCC) to replace the conventional gas / liquid heat exchanger (HX) at the stripper overhead. Three scenarios were proposed and assessed for DCC configuration: open, closed, and combined DCC circuits. It was found that combined‐circuit DCC could better enhance the CO2 product's purity, bringing its temperature to the nominal target, and producing less condensate, which is diluted and easier for downstream integration. Most important, this configuration can effectively eliminate ammonia slipping in the product line and solid precipitation at the stripper overhead. Validating these improvements at our current pilot plant would bring tremendous benefits for the commercialization of this technology. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.