Research And Application Of Double Membrane Coupling Separator

In the hollow fiber membrane separator for gas separation, the enrichment of slow gas in the feed side reduced mass transfer impetus of fast gas, which had an adverse effect on the permeability of fast gas. It was proposed that using double membrane coupling separator to reduce this effect, and to improve the separation efficiency of the membrane process.The mathematical model was established to express gas separation process in double membrane coupling separator with three flow patterns, which were perfect mixing, cocurrent and countercurrent. The solving procedure was embedded into the UniSim software for solving. Compared the model calculation values with the experimental values in the literature, countercurrent flow pattern was preferable.Choose the recovery of H2from carbon monoxide shift gas in coal gasification as background, the influence of various parameters on the performance of double membrane coupling separator was analysised.The results show that:countercurrent is more advantageous to the gas separation than the cocurrent flow pattern; increasing the membrane area ratio is in favor of H2recovery, and the performance of double membrane coupling separator is better than the single membrane separator; increasing the feed pressure can increase the H2concentration and recovery rate in the permeate side of the PEI membrane; improving the performance of two kinds of membranes in double membrane coupling separator (increase the permeation rate and separation coefficient) can improve the membrane separation performance. The performance of two single membrane separator in series scheme was compared with the double membrane coupling separator for separating mixed gas.the results showed that for recovery of H2, double membrane coupling separator can get the highest recovery rate, but the PEO-PEI series can get the highest molar content.A comprehensive recovery process was developed to recover hydrogen and light hydrocarbon from refinery vent gases in a large petrochemical plant. The process composed of three parts:hydrogen recovery, light hydrocarbon recovery and multistage membrane separation. The technology used in the process included compression/condensation, gas desulfurization, TSA dehydration, hydrogen membrane separation, VOC membrane separation and distillation. The annual production of H2, LPG, and light petroleum are6.1×107Nm3,1.31×105ton, and1×104ton respectively. The quality of the materials separated through the process meets the requirement that they can be used as products or production materials by the plant. Through the primary economic analysis, the annual economic benefit of the process reached2.8×108yuan.Double membrane coupling separator was used for uncondensed gas recovery, the light hydrocarbon recovery rate increased from82.8%to98.7%compared with multistage membrane separation, for the200000tons/year refinery gases recovery, the annual economic benefits increased9.19million yuan. Three schemes was used to recover H2from PSA purge gas, compared the PEI membrane separator scheme with the double membrane coupling separator scheme, the H2concentration increased from74.38%to80.12%, H2recovery rate from48.24%to54.66%, but the PEO-PEI series scheme get the highest H2concentration and recovery rate of83.46%and56.18%respectively.