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为避免浮顶储罐在遭受雷击时由于导电片设施在二次密封油气空间中放电引起密封圈火灾,在实验室建立了2 m直径油罐模型,开展导电片火花放电起始电流试验、导电片与罐壁形成空气间隙击穿放电初始电压试验,系统研究导电片在二次密封油气空间中的放电危险性。试验结果表明:导电片靠自身弹性与罐壁贴合时,雷电流大约在400 A时导电片开始产生点燃性火花放电;如导电片与罐壁贴合不良形成空气间隙,雷击情况下雷电流泄放瞬时浮顶与罐壁之间的电位差足以使一定大小的间隙击穿放电,当间隙大小为20~30 mm时,放电电压为26~40 kV。因此,储罐在遭受雷击时,导电片火花放电现象不可避免。结合储罐的实际运行情况,提出取消二次密封导电片、液下刮蜡器与浮顶进行可靠电气连接的改进措施,避免导电片在二次密封油气空间中放电发生,大大降低浮顶储罐雷击火灾事故。
In order to avoid the floating ring fire caused by lightning discharge in the floating oil and gas space, a 2 m diameter tank model was established in the laboratory to carry out the spark discharge starting current test of conductive sheet, The initial voltage test of air gap breakdown discharge is formed between the film and the tank wall, and the discharge risk of the conductive film in the secondary seal oil and gas space is systematically studied. The experimental results show that when the conductive sheet is bonded to the tank wall by its own elasticity, the sparking spark discharge starts to occur at the conductive sheet at about 400 A; if the conductive sheet and the tank wall are badly bonded to form an air gap, the lightning current Leakage The potential difference between the instantaneous floating roof and the tank wall is sufficient to cause a breakdown discharge of a certain size, with a discharge voltage of 26-40 kV at a clearance of 20-30 mm. Therefore, when the tank is struck by lightning, the spark discharge phenomenon of the conductive sheet is inevitable. Combined with the actual operation of the tank, proposed to eliminate the secondary seal conductive sheet, liquid scraper and floating roof reliable electrical connection improvements to prevent the conductive sheet in the secondary seal oil and gas space discharge occurred, greatly reducing the floating roof storage Lightning fire cans.