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

Gas separation properties of membranes are the significant parameters in CO2 capture process. It has been reported that membranes with high permeance and moderate CO2/N-2 selectivity are suitable for CO2 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 CO2 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 CO2-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.