Concentration polarization in Pd based membrane for the separation of H2/He
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摘要: 根据设计,未来聚变堆等离子体排灰气中除了氘氚还含有以惰性气体为主的杂质气体,会在钯膜纯化氢同位素的过程中产生不容忽视的浓差极化现象,降低排灰气的处理效率。针对这一现象,以氢氦混合气为源项,研究了钯膜在分离氢氦过程中浓差极化对渗氢性能的影响,利用极化系数对浓差极化的程度进行评估,并考察了渗氢驱动力、氦气浓度以及原料气流量对极化系数的影响。结果表明:在150,300,450 kPa时的H2/He选择性分别为37 460,18 347和7935,可以看出钯膜致密性良好;浓差极化系数随着渗氢驱动力和氦气浓度的升高而增大,对于原料气流量的变化则呈现相反趋势。Abstract: Based on the current ITER design, there will be 12% inert gases in the off-gases from the torus collected in the cryopumps. The concentration polarization existing in the Pd membraneseparation processes could seriously affect the processes. In this work, the concentration polarization phenomenon in a porous ceramic supported Pd-based membrane for the separation of H2/He has been studied. A polarization coefficient was defined to describe the extent of the concentration polarization phenomenon, the effect of operation parameters such as operation pressure, upstream He molar fraction, and feed gas flow rate on the coefficient were investigated. The results show that the degree of inhibition by concentration polarization in hydrogen permeation decreases with increasing feed gas flow rate, whereas increases with rising He molar fraction and upstream total pressure.
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