Rate-based modelling of combined SO₂ removal and NH₃ recycling integrated with an aqueous NH₃-based CO₂ capture process

Highlights: • A rigorous, rate-based model for an NH₃–CO₂–SO₂–H₂O system was developed. • Model predictions are in good agreement with pilot plant results. • >99.9% of SO₂ was captured and >99.9% of slipped ammonia was reused. • The process is highly adaptable to the variations of SO₂/NH₃ level, temperatures. - Abstract: To reduce the costs of controlling emissions from coal-fired power stations, we propose an advanced and effective process of combined SO₂ removal and NH₃ recycling, which can be integrated with the aqueous NH₃-based CO₂ capture process to simultaneously achieve SO₂ and CO₂ removal, NH₃ recycling and flue gas cooling in one process. A rigorous, rate-based model for an NH₃–CO₂–SO₂–H₂O system was developed and used to simulate the proposed process. The model was thermodynamically and kinetically validated by experimental results from the open literature and pilot-plant trials, respectively. Under typical flue gas conditions, the proposed process has SO₂ removal and NH₃ reuse efficiencies of >99.9%. The process is strongly adaptable to different scenarios such as high SO₂ levels in flue gas, high NH₃ levels from the CO₂ absorber and high flue gas temperatures, and has a low energy requirement. Because the process simplifies flue gas desulphurisation and resolves the problems of NH₃ loss and SO₂ removal, it could significantly reduce the cost of CO₂ and SO₂ capture by aqueous NH₃