Modeling Solid-liquid Equilibrium of the NH3-CO2-SO2-K2SO4-H2O System and Its Application to Combined Capture of CO2 and SO2 Using Aqueous Ammonia

It is of significance to intensively investigate the solid-liquid equilibrium of the NH3-CO2-SO2-K2SO4-H2O system to assess the novel aqueous NH3 based CO2 and SO2 combined capture process proposed in our previous work. In this work, the solubility of K2SO4 in aqueous NH3 at various temperatures, CO2 and SO2 loadings, and NH3 concentrations was predicted using Aspen Plus with a developed thermodynamic model package, which can accurately simulate the vapor-liquid equilibrium and the solid-liquid equilibrium of the combined CO2 and SO2 capture system. The results indicate that the solubility of K2SO4 increases with temperature and CO2 loading, but decreases with NH3 concentration. The precipitation starting point of K2SO4 shift to higher temperature with the increasing of SO2 loading and NH3 concentration. It is favorable to collect K2SO4 precipitates at lower CO2 loading and temperature, and higher SO2 loading and NH3 concentration.