5种管道密封材料在超临界CO_2中的溶胀规律

Swelling behavior of five seal materials used for supercritical CO_2 pipeline

为了解管道密封材料在超临界CO_2输送环境的适用性,采用横截面直径、外径、硬度和质量测量及形貌观察等方法研究了三元乙丙橡胶(EPDM)、丁腈橡胶(NBR)、聚四氟乙烯(PTFE)、聚三氟氯乙烯(PTFCE)和聚醚醚酮(PEEK)5种密封材料在超临界CO_2中的溶胀规律。结果表明:在35℃、8 MPa,水饱和度为60%,饱和含水量及水相的条件下,EPDM和NBR发生了明显溶胀现象,横截面直径及外径明显增加,表面出现了较多开裂和鼓包;5种材料的硬度均有下降,质量未发生明显变化;5种密封材料性能未随超临界CO_2中的含水量发生明显变化。在水饱和度为60%条件下,随实验时间的增加,EPDM和NBR的溶胀现象变得更加明显,PTFE和PTFCE的硬度有所降低。PEEK在各含水量及实验时间条件下均表现出优良的性能。

To understand the applicability of seal materials in supercriticalswelling behaviors of the ethylene propylene diene monomer（EPDM）,nitrile rubber（NBR）,polytetrafluoroethylene（PTFE）,polytrifluorochloroethylene（PTFCE）and polyether-ether-ketone（PEEK）in supercriticalwere investigated by the measurement of change rate of cross-section,outer diameter,shore D hardness,mass and morphological observation.The results showed that excessive swelling,crack,blister and an increase of change rate of cross-section diameter and outer diameter was observed for EPDM and NBR at 35MPa when the water content was 60%,saturated and in free water.A reduction of shore D hardness and no obvious change of mass was noticed for all five seal materials.The properties of five seal materials didn’t change significantly with water content in supercritical CO2 environment.Swelling of EPDM and NBR became more serious and shore D hardness of PTFE and PTFCE decreased with increasing exposure time when the water content was 60% saturated.PEEK showed excellent performance under various water content and exposure time.