Study On The Intensification Of Mass Transfer Of CO₂ Absorption By Naoh Solution Based On Hollow Fiber Membrane

Since the industrial revolution, the climate and environmental problems including global warming, melting glaciers and extreme weather which caused by the excessive emission of greenhouse gases such as carbon dioxide (CO2) has got the attention of all over the world. The advantages of hollow fiber membrane are the high specific surface area and low cost. Hence, the membrane absorption technology is regard as one of the most effective methods for CO2 capture. However, the membrane in the CO2 absorption process enhances the mass transfer resistance and reduces the mass transfer efficiency. Based on the Laplace-Young law, this paper proposes the assumption by strengthing the turbulence level of gas-liquid interface to enhance the mass thansfer perdormance and designs the experiments to verify.In this paper, the self-made hollow fiber membrane contactor (HFMC) is used for CO2 capture and investaiages the effect of factors on mass transfer performance of steady state and nonsteady gas-liquid interface. The results are as follows. The mass transfer coefficient for both situations increases with the increasing of absorbent concentration and absorbent flow rate, decreases with the increasing of gas flow rate and CO2 content. The enhancement factor is up to 6 times in this experiment. For long term operation, the mass transfer coefficient for both situations firstly decreases and then tends to be gentle and the stable value is 25% and 50% for steasy state and nonsteady state experimnent. The total absorption by nonsteady state experimnent in 24 h is 1.5 times of that by steady state experimnent. Hence, the nonsteady gas-liquid interface can effectively enhance the absorption rate.By analyses the mass transfer mechanism, the mass transfer resistence is calculated for both situations. Compared with steasy state experimnent, the overall mass transfer resistence is reduced by 40% with membrane resistence accounted for over 90%. The mass reansfer correlations have been correlated with dimensionless numbers. Sh= 0.670 (L/Di) -0.084 Re 0.846 Sc0.333 and Sh= 2.204(L/Di)-0.592 Re 0.801 Sc0.333 are under co-counter and counter-current for steadty state and the deviation between theoretical value and experimental value is ±15% and ±10%, respectively. Sh= 29.3 (L/Di)-1.01 Re0.314 Sc0.333 and Sh= 0.670 (L/Di)-0.084 Re 0.846 Sc0.333 are under co-counter and counter-current for nonsteadty state and the deviation between theoretical value and experimental value is ±20% and ±10%, respectively. At last, the mass transfer model is established and the fitting values are good agreement with experimental results.