Techno-economic evaluation of a novel membrane-cryogenic hybrid process for carbon capture

Abstract

• Sub-ambient membrane-cryogenic process was designed for carbon capture. • Effect of selectivity-enhanced membrane were explored. • Parasite load of CFG and BFG decreased 7.11% and 15.55% respectively. • Hybrid process was competitive for scenarios with high CO 2 -content flue gas. Gas separation properties of membranes are the significant parameters in CO 2 capture process. It has been reported that membranes with high permeance and moderate CO 2 /N 2 selectivity are suitable for CO 2 capture from coal-fired flue gas. However, with emerging high selectivity membrane and novel processes, it is essential to evaluate the influence of membrane selectivity on carbon capture performance, especially the significance of sub-ambient membrane operation. In this work, a sub-ambient membrane-cryogenic hybrid process was designed for CO 2 capture from coal fired and blast furnace flue gas. It was found that energy consumption of vacuum can be saved when membranes with high selectivity were operated at sub-ambient condition. The cost and energy consumption of the optimal cases for coal fired flue gas were 36.14 $/tCO 2 and 1.87 GJ/tCO 2 according to the economic evaluation. The parasite load decreased 7.11% over the base case of 168 MW. In addition, the capture cost and energy consumption of optimal case for blast furnace flue gas were 28.81 $/tCO 2 and 1.55 GJ/tCO 2 , respectively. The parasite load decreased 15.55% over the base case of 17.81 MW. The designed hybrid processes presented competitive potential when applied in high CO 2 -content scenarios. In summary, the hybrid process based on membranes and cryogenic has been proven to have economic advantages under simulated conditions, indicating that it has the potential to be amplified by industrialization.