Advancement of ammonia-based post-combustion CO2 capture technology: Process modifications

Abstract

Aqueous ammonia (NH3)-based capture process has the potential to simultaneously remove NOx/SO2/CO2 pollutants at low cost, but conventional NH3-based process suffers high NH3 slip, high energy consumption and high capital investment. The present study aims to advance the NH3-based scrubbing technology to overcome these technical issues. We used inter-cooled CO2 absorber to mitigate the NH3 emission and enhance CO2 absorption, while employed advanced flash stripper configuration to significantly decrease the absorbent regeneration duty. We also proposed an effective NOx/SO2 removal process by utilizing the slipped NH3 for multi-pollutant emission control. A validated model was used to gain insight into the techno-economic performance of this advanced NH3-based NOx/SO2/CO2 removal process, and important process parameters such as absorption temperature, NH3 concentration and flue gas NOx/SO2 concentrations were investigated in detail. The results indicate that the advanced NH3 process enabled great capital saving by 23% and energy saving by 42%, resulting in a low CO2-avoided cost of US$44.3/t CO2, which is 42.8% lower than the baseline NH3 process.