Integrated hybrid process for solvent-based CO₂ capture using a pre-concentrating membrane: A pilot scale study

A new integrated hybrid system for post-combustion CO₂ capture involving a pre-concentrating membrane and solvent-based absorption was designed, fabricated and tested at a 0.1 MWth pilot-scale CO₂ capture unit using coal-derived flue-gas. The tests were performed with a proprietary solvent and 30 wt% mono-ethanolamine (MEA). The pre-concentrating membrane increased inlet CO₂ concentrations in the flue gas from 14 vol% to up to 28 vol%., increasing the driving force for mass transfer of CO₂ from the gas-phase to the solvents for higher rich carbon loadings in the absorber. With enhanced mass transfer, lower liquid circulation rates for the hybrid process (L/G = 3 compared to 5 for solvent-based only process) and the resultant sensible heat reduction contributed to specific reboiler heat duty savings of about 30%. The additional electrical energy consumption from auxiliary equipment in the hybrid process such as the vacuum pump, however, contribute to lower the total energy benefit for the process.