Development of an advanced, aqueous ammonia-based CO2 capture technology: Pilot plant demonstration and techno-economic assessment

Aqueous ammonia (NH3(aq)), as a viable CO2 absorbent, possesses many advantages over amine based capture agents. Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) developed an advanced, NH3(aq) based capture technology for applications in energy and industrial sectors and has recently demonstrated the technology at pilot scale in an Australian coal fired power station. The pilot plant trials have confirmed the benefits of the process improvements including (1) the combined flue gas cooling, SO2 removal and NH3 recovery; (2) recycle absorption; (3) stripper rich split. Comparison of pilot plant and modelling results confirmed that our existing process model can reasonably predict SO2 removal, CO2 absorption and regeneration using NH3(aq). A relatively large discrepancy occurred when the model was used to predict NH3 recovery, likely due to a low liquid flow in a large column, which may lead to poor mixing between gas and liquid. We also assessed the techno-economic performance of a commercial-scale, NH3(aq)-based CO2-capture process integrated with a new pulverised coal-fired power station in Australia. The NH3(aq)-based CO2 capture equipped with process improvements tested in pilot-plant trials and advanced flash stripper had lower auxiliary energy consumption than a monoethanolamine (MEA)-based CO2-capture process. The net plant efficiency with integration of the advanced NH3 process decreased from 40 to 33.8% compared with 30.9% for MEA. The levelized cost of electricity and the cost of CO2-avoided for the advanced NH3 process were 15% and 31% lower than those of the reference MEA process respectively. The pilot plant demonstration and techno-economic assessment have suggested that the advanced NH3 process can offer a cost competitive option for significant reduction of CO2 and SO2 in various industries.