五种吸附剂与C_(4)F_(7)N气体及CF_(3)SO_(2)F气体的相容性试验研究

Experimental Study on Compatibility with C_(4)F_(7)N and CF_(3)SO_(2)F Gases and Five Adsorbents

全氟异丁腈(C_(4)F_(7)N)和三氟甲基磺酰氟(CF_(3)SO_(2)F)是两种具有应用前景的SF_(6)替代气体,有必要研究其与设备中常见吸附剂的相容性。该文通过试验研究了五种常用的吸附剂(3A分子筛、4A分子筛、5A分子筛、13X分子筛及活性氧化铝)与C_(4)F_(7)N气体、CF_(3)SO_(2)F气体的相容性,采用C_(4)F_(7)N/CO_(2)、CF_(3)SO_(2)F/N_(2)混合气体进行试验,检测试验前后混合气体的比例及成分,发现活性氧化铝会使C_(4)F_(7)N气体体积分数下降,但不会使CF_(3)SO_(2)F气体体积分数下降;其他几种吸附剂均不会使两种气体体积分数下降。分析表明,C_(4)F_(7)N气体分子的CN基团会与活性氧化铝发生弱相互作用,从而导致其被活性氧化铝吸附,因此活性氧化铝不适合作为C_(4)F_(7)N气体设备中的吸附剂。该文涉及的五种吸附剂均与CF_(3)SO_(2)F气体相容。

SF_(6)is an advantageous insulation gas that is widely applied in electrical equipment all over the world.However,the high global warming potential(GWP)it possesses prevents it from continuous application due to environment-friendly targets.In this circumstance,a variety of environment-friendly insulation gases have entered the field of view of researchers.Perfluoroisobutyronitrile(C_(4)F_(7)N)and trifluoromethylsulfonyl fluoride(CF_(3)SO_(2)F)are two novel environment-friendly gases replacing SF_(6).Researchers have conducted a bunch of studies to test the dielectric properties and other properties of two gases by different methods.To promote the use of environment-friendly gases in industrial applications,it is necessary to study the compatibility between environment-friendly gases and common adsorbents in electrical equipment.Compatibility means that a kind of material will not have physical changes or chemical changes if contacted by other kinds of material.Recent research indicated that activated alumina is incompatible with C_(4)F_(7)N while there is little research on the compatibility of adsorbents with CF_(3)SO_(2)F.To find out the compatibility between the adsorbents and CF_(3)SO_(2)F and to verify the test methods used in this paper,a series of tests were performed.According to the gas application scheme that the researchers have introduced,20%C_(4)F_(7)N/80%CO_(2) mixed gas under 0.6 MPa and 40%CF_(3)SO_(2)F/N_(2)mixed gas under 0.4 MPa were used for the compatibility test.The mixed gas and the adsorbents were put into gas containers made of stainless steel at 25℃.The GC-MS tests and GC tests aimed to analyze the collected gas after the tests were performed 7 days later.The mass of the adsorbents was measured by precision balances before and after the tests to find out how much weight the adsorbent increased through the adsorption process.The gas and adsorbents test results were compared to find out if the target environment-friendly gas was adsorbed.The adsorption effect of five commonly used adsorbents(3A molecular sieve,4A molecular sieve,5A molecular sieve,13X molecular sieve,and activated alumina)on C_(4)F_(7)N/CO_(2) and CF_(3)SO_(2)F/N_(2)gases was experimentally studied.Firstly,the gas chromatography-mass spectrometry(GC-MS)results show that there is no extra gas produced in both tests for C_(4)F_(7)N and CF_(3)SO_(2)F which indicates that there are no chemical changes during a 7-day test.By detecting the proportion and composition of mixed gases before and after the test through gas chromatography(GC)test,it is found that activated alumina can obviously reduce the proportion of C_(4)F_(7)N by 1.88%which can be converted to 0.257 g while no similar result was observed for CF_(3)SO_(2)F.Other adsorbents will not reduce the ratio of the two gases.The increased mass of the adsorbents was calculated and the increased mass of the activated alumina adsorbent is 0.282 g which is approximately equal to the decreased mass of C_(4)F_(7)N considering the errors in the test.Because GC-MS test result reveals that no chemical change between C_(4)F_(7)N and activated alumina during the test,the adsorption effect is considered physical adsorption.The analysis shows that the CN group of C_(4)F_(7)N molecule has a weak interaction with activated alumina,which leads to its adsorption by activated alumina.Therefore,activated alumina is not suitable for use as an adsorbent in C_(4)F_(7)N gas-insulated equipment,and the five adsorbents involved are all compatible with CF_(3)SO_(2)F.