Parametric investigation of CO2 capture from industrial flue gases using aqueous mixtures of ammonia (NH3) and potassium carbonate (K2CO3)

The industrial sector has a significant contribution to global CO2 emissions. Aqueous mixtures of NH3 and K2CO3 seem to be promising solvents for the capture of CO2 from industrial flue gases. The CO2 capture from simulated industrial flue gases with CO2 between 10%v/v and 30%v/v was evaluated, considering nominal capture rate of CO2 (CCO2) 90%. The effect of pressure on the solvent regeneration was investigated in the range 5–15 bar. Aspen plus software and the Extended UNIQUAC thermodynamic model were used in equilibrium-based calculations. The aqueous mixtures of NH3 - K2CO3 had lower heat of desorption of CO2 than that in aqueous NH3. K2CO3 effect on NH3 slip from the absorption column was influenced by the concentration of CO2 in gas phase and the composition of solvent. The reduction in NH3 slip by K2CO3 was pronounced in solvents with high NH3 content, ≥4.54 mol/kgH2O. The NH3 slip increased by K2CO3 when solvents with low content of NH3 were used. The presence of K2CO3 in solvents with high CO2 loading, ≥0.4, was not beneficial in terms of NH3 slip. The increase in the pressure of regeneration resulted in an increase in the temperature of regeneration and a decrease in the heat duty of the reboiler.