基于高分子膜的SF_(6)/N_(2)混合气体分离技术研究

Experimental Research on Separation Technology of SF_(6)/N_(2)Mixture Based on Polymer Mem brane

六氟化硫/氮气(SF_(6)/N_(2))混合气体作为六氟化硫(SF_(6))替代气体被广泛研究,并已在多个电站GIS设备中进行试点应用。在进行GIS设备维护时,迫切需要高效的分离方法来实现混合气体中SF_(6)气体的回收。目前常用的混合气体分离技术主要有液化、低温蒸馏、吸附分离等,但由于分离效率低,并不适用于现场SF_(6)/N_(2)混合气体的分离回收。文中采用膜分离技术,选取玻璃态聚酰亚胺气体分离膜,测试了不同压力和温度条件下SF_(6)和N_(2)的渗透效果,确定了在适宜的温度和压力下,该分离膜的N_(2)/SF_(6)分离选择性可以达到39以上,N_(2)的渗透速率可以达到2.73 GPU以上,具备将SF_(6)和N_(2)分离的能力。在此基础上,测试了单级分离膜分离效果,根据测试结果,选择进入分离膜的气体压力为2.00 MPaG、温度为60℃,设计了三级循环膜分离系统,实现分离后SF_(6)纯度达到95%以上,排放尾气中SF_(6)含量不超过0.05%。

Sulfur hexafluoride/nitrogen(SF_(6)/N_(2))mixture had been widely studied as a substitute gas for SF_(6).It has been applied in GIS equipment of many power stations.In the maintenance of GIS equipment,there was an urgent need for efficient separation methods to realize the recycle of SF_(6)gas in mixed gas.At present,the main methods of mixed gas separation include liquefaction,low-temperature distillation,adsorption separation,etc.However,due to the low separation efficiency,it was not suitable for on site separation and recycle of SF_(6)/N_(2)mixed gas.In this paper,the glass polyimide gas separation membrane was selected,and the permeation effects of SF_(6)and N_(2)under different pressure and temperature conditions were tested.It was determined that under the appropriate temperature and pressure,the N_(2)/SF_(6)separation selectivity of the separation membrane can reach more than 39,and the N_(2)permeation rate can reach more than 2.73 GPU,which had the ability to separate SF_(6)and N_(2).On this basis,the separation effect of single-stage separation membrane was tested.According to the test results,the pressure of the gas entering the separation membrane was 2.00 MPaG and the corresponding temperature was 60℃,and a three-stage circulating membrane separation system was designed.After separation,the purity of SF_(6)reaches more than 95%and the content of SF_(6)in the exhaust gas did not exceed 0.05%.