A feasible energy-saving analysis of a new system for CO2 cryogenic capture

A new CO2 cryogenic capture and liquefaction system has been proposed previously in order to separate CO2 from exhausted gases and make it as a resource for industry. This system combines CO2 cryogenic capture with N2/O2 separation together. Its energy consumption is lower than the traditional amine solution capture process as theoretical analysis. In this study, the simulation of the proposed system with several improvements was carried out aiming to reduce the energy consumption further. Many heat exchangers were introduced and the heat exchanger arrangements were optimized to recycle the refrigeration capacity from the returned N2 after the N2/O2 separation. The discharge pressure of mixture gas from the compressor was reduced from 10 to 3.493 MPa. The simulation results showed that the compression work could be greatly reduced and the energy consumption of CO2 capture in this new system after these improvements reached 2.884 GJ/ton CO2. The new system is promising because not only liquid or solid CO2 could be produced but also N2 and O2 could be separated.