Post-combustion CO2 capture with sweep gas in thin film composite (TFC) hollow fiber membrane (HFM) contactor

摘要

In the current work, mini-modules of composite hollow fiber membranes (HFMs) were fabricated by dip-coating poly(vinylidene fluoride) (PVDF) fibers in Polydimethylsiloxane (PDMS) with tri-layer for 10 s at 298 K with 5 s of time laps for each immersion. The HFMs were prepared from PVDF/Dimethylacetamide (DMAc)/Additive systems by nonsolvent induced phase separation (NIPS) technique. The composite HFMs were tested for CO2 permeation, CO2 enrichment (recovery ratio) and permselectivity of CO2/N-2, for pure and mixed gases under both feed compression and permeate vacuum. The modules were then investigated for post-combustion CO2 capture for mixed gas permeation under feed compression and countercurrent sweep mode. The effects of pressure ratio, sweep gas ratio and temperature were also investigated on CO2 capture. The fabricated HFMs with 2 wt % PDMS solution produced the dense layer thickness of 0.44 pm which achieved the CO2 permeance, permselectivity and CO2 recovery ratio upto 2049 GPU, 27 and 0.38, respectively. In case of mixed gas (CO2/N-2 in volume ratio of 15/85 %) permeation, the composite HFM modules were tested up to pressure ratio of 4, sweep ratio of 1.4, temperature of 323 K and for 30-h long duration. Under these conditions, the maximum CO2 permeance, permselectivity and CO2 recovery ratio were achieved up to 1854 GPU, 34 and 0.32, respectively. The composite HFMs showed promising results and could be useful in post-combustion CO2 capture, particularly in coal/natural gas-based power plants.