| For the purpose of oil vapor recovery,this paper studied the preparation of hollow fiber membrane,the recovery of oil vapor by membrane absorption method and the simulation of absorption-desorption-recovery process by ASPEN PLUS software.Firstly,immersion phase conversion method was used to prepare hollow fiber membrane.Polyetherimide(PEI)was used as membrane material,n-dimethylpyrrolidone(NMP)was used as solvent,and different amounts of glycerol and water were used as nonsolvent additives.The membrane was characterized by scanning electron microscope(SEM),atomic force microscope(AFM),universal testing machine,surface contact Angle tester and porosity test,and the effects of glycerol or water with different mass ratios as non-solvent additives on the microstructure,mechanical properties and hydrophilicity of polyimide hollow fiber membrane were studied.The results showed that when glycerol was used as a non-solvent additive,the thickness of sponge layer in the hollow fiber membrane decreased with the increase of glycerol content,and the finger-like space increased at the same time,which was helpful to improve the porosity and strength of PEI hollow fiber membrane.When glycerol content was controlled at 5 wt.% or 6 wt.%,the strength of hollow fiber membrane was improved best.With the increase of water content,the structure on the side near the outer surface gradually becomes looser and more porous,and the number of membrane holes and pore area increase obviously.When the water content is 4 wt%,the cross section structure near the outer surface presents a reticular structure.With the increase of water content of the additive,the pore density of the hollow fiber membrane surface decreases,the pore size increases and the roughness also increases.But its oil-repellent property improves ceaselessly.In the process of membrane absorption,the prepared PEI hollow fiber membrane is used to absorb oil vapor.The smaller the gas flow rate of the outlet is,the better the oil vapor absorption effect of the absorption membrane module on the mixed gas is.When high temperature thermal conductivity was used as the absorbent in the process of the test,the absorption effect of the film assembly on n-hexane gas was the best.When the difference between the flow rate of the absorbent and the absolute value of the gas flow rate in the inner diameter of the hollow fiber membrane is between 0.2 L/min and 0.5 L/min,the better the absorption effect of the absorbent membrane module on oil vapor is.When the gas outlet flow rate was 1 L/min,the absorbent was high temperature thermal conductivity oil and the flow rate was 1.45 L/min,the absorption rate of n-hexane in the mixed gas with 5% glycerol content was 97.68%.The absorption-desorption-recovery simulation was established by using ASPEN PLUS software.In the model,the contents of benzene,n-hexane and isohexane in the oil vapor components in the mixed gas were set as 6%,4% and 1%,respectively.The gas feed flow rate is 200 kmol/h,the absorbent feed flow rate is 55 cum/h,the desorption tower(namely the flash tank)temperature is 100 ?.The simulation results show that the recovery rate of oil vapor is 99.99 %.The simulation results prove the feasibility of absorbing oil vapor and then desorbing the absorbent after the membrane absorption process. |
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