4E evaluation and multi-objective optimization of low concentration flue gas CO2 capture and multi-product conversion process

Abstract

In order to address the current global warming, this work proposes CO2 capture from flue gas and CO2 hydrogenation to produce methane, methanol, and CO2 to produce ammonium bicarbonate. Aspen Plus process simulation model is developed for the three processes. Based on the thermodynamic model, sensitivity analysis of main operating parameters is conducted on the energy, economic, environment, and exergy (4E) indicator. Non-dominated sorting genetic algorithm is used to achieve multi-objective optimization. The optimum operating parameters of the three processes are obtained under the 4E indicators. It is concluded that the CO2 to ammonium bicarbonate is the optimal process route for CO2 conversion. The corresponding total annual cost is 4.071 M$/year, the CO2 equivalent emission per unit product is −0.0667 tCO2/t pro, the annual total utility consumption is 7062.75 kW/year, and the exergy efficiency of system is 53.42 %. This work shows significance for achieving resource utilization with capture CO2.