变压膜渗透空气分离制氮

在稳态膜渗透的基础上提出了一种新的非稳态渗透流程.该流程是一种循环操作过程,每一周期包含加压、抽真空以及排空三个阶段. 实验研究了加压时间、抽真空时间和排空时间对空气分离制氮的产品平均纯度、产率和回收率的影响,并与稳态渗透实验结果进行了比较. 结果表明,随着加压时间的延长,富氮气体的平均纯度、产率以及氮气回收率均会上升;延长抽真空时间可以提高富氮气体平均纯度,但会降低富氮产率和氮气回收率;适当延长排空时间可以提高富氮气体平均纯度、产率和氮气回收率,但排空时间过长将会导致富氮产率和氮气回收率下降. 本文提出的变压渗透过程能够得到比稳态渗透更高的富氮纯度,但富氮产率和回收率要低.

Separation of nitrogen from air by pressure swing membrane permeation

A novel unsteady-state membrane permeation process was proposed based on steady-state permeation. The process is composed of three basic cyclic steps: feed pressurized, permeate withdrawn, and residue vented. The effects of pressurization time, evacuation time and venting time on the average purity, productivity and recovery of nitrogen were experimentally investigated for air separation to produce nitrogen by this process. The effectiveness of the process was compared with that of steady-state permeation. The results show that the average purity, productivity and recovery of nitrogen increase with the prolonging of pressurization time under the experimental conditions. The average purity of nitrogen-enriched gas is increased but its productivity and recovery are decreased when the evacuation time is extended. An appropriate increase in venting time is associated with the increases of average purity, productivity and recovery of nitrogen. When the venting time is too long, the productivity and recovery will be decreased. As a result, the proposed process in this paper can achieve a higher purity of nitrogen but a lower productivity and recovery.