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

Aqueous ammonia (NH₃)-based capture process has the potential to simultaneously remove NO_x/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 NO_x/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 NO_x/SO₂/CO₂ removal process, and important process parameters such as absorption temperature, NH₃ concentration and flue gas NO_x/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.