浮顶储罐二次密封装置的雷击危险性

Lightning risk for the secondary seal that of floating-roof tank

大型浮顶油罐通常安装二次密封装置,其所处位置存在燃爆油气空间,极易导致雷击火灾事故。雷击危险性理论指出:二次密封装置的导电片依靠外界弹力贴合,并非连续可靠的电气连接,在雷电流流过时存在产生火花放电的可能性。采用8/20s冲击电流波进行雷击危险性实验验证,结果表明:导电片与罐壁接触越可靠,越不易产生雷击打火;油污能够在一定程度上抑制火花的出现,但无法起到绝缘作用,雷电流仍然会通过导电片并产生火花放电现象;雷电流通过导电片时,电流只需达到几百安培即可引起火花放电。基于上述结论,提出了建议措施,对于确保大型浮顶储罐防雷击安全运行具有指导作用。

Generally,large-scale floating-roof oil tank works with the secondary seal,however,where exists a space from light gas to blast induced by lightning stroke,or fire accident.Lightning theory indicates that conducting strip of secondary seal is attached by external elastic force instead of continuous and reliable electrical connection,which has the probability of spark discharge when the lightning current is flowing through the conducting strip.The result of lightning risk experiment applying 8/20 μs impulse current wave shows that the more reliable connection between conducting strip and tank wall is,the more difficult for lightning striking is.The oil dirt may control the appearance of spark to a certain degree,but lightning current may still pass through the conducting strip and produce spark discharge for the shortage of insulation function.When lightning current passes through the conducting strip,only several hundreds ampere of current can cause spark discharge.Based on the above conclusions,the proposed measures are presented,which acts as the guidance function to ensure the safety operation of large-scale floating-roof oil tank against lightning.