闪电定位资料对仪征储油罐雷灾成因的分析应用

AN APPROACH TO THE CAUSE OF FORMING THE LIGHTNING STRIKE DISASTER OF OIL TANKS IN YIZHENG ACCORDING TO THE LIGHTNING FLASH POSITIONING DATA AND AN APPLICATION

本文根据多普勒天气雷达回波与闪电定位仪资料,结合雷电现场进行实地勘查的结果,探讨2006年8月7日发生在扬州市仪征油罐雷电灾害事故。综合分析发现当时强对流回波达55 dBz、顶高14 km;在距油罐1 km范围内有闪电13次,负电荷集聚、强度多在20~50 kA之间。此次雷灾事故的直接致灾原因是强大的感应雷电脉冲电流在储油罐罐体与浮顶两根连接电缆上产生较大的电压,导致储油罐罐体与浮顶之间在密封处产生闪络,引起油汽外泄燃爆成灾。为减少此类雷电灾害的发生,提出防护建议。

The Yizheng oil tanks in Yangzhou city were struck by stormy lightning on Aug. 7,2006. The present article is an approach to the cause of forming a fire disaster arising from the above-said lightning strikes in accordance with the Doppler weather radar echoes and the data shown on the lightning flash positioning indicators, and in accordance with the on-the-spot investigation results recorded at the lightning strike site. An overall analysis indicates： the strong convective echo recorded at that time reached 55 dBz; the cloud top developed to 14km; the lightning was recorded for 13 times within an area 1km away from the oil tanks; and the accumulated minus charge had a strength of 20-50 kA. The immediate cause for the above-said lightning strike disaster lies in the great voltage generated by the strong lightning-induced im- pulse current at two cables for connecting an oil tank body and its floating roof. It is due to this great voltage that a flashover was generated at the airtight seals between the oil tank bodies and their floating roofs. And it is just this flashover that enables the oil and the oil vapour to leak out to catch fire. In order to reduce the occurrence of such lightning strike disasters,we have worked out a protection proposal accordingly.