LNG供气站重大事故风险及定量评价

Improved quantitative risk-assessment method for major accidents of LNG gas station

为对LNG供气站进行综合评价,分析了LNG站的事故因素及其来源。根据事故特征,采用冲击波超压和火球热辐射评估模型。采用蒙特卡罗随机模拟方法(Monte-Carlo)确定模型中源项的数据分布及概率。编制事故危害程度和危害范围的计算程序,并对某LNG站进行了定量风险评价(QRA)计算。计算确定了空间各点的事故概率分布、风险等级及LNG供气站的综合风险指数。计算结果表明,某LNG站的死亡事故率为6.94人,平均个人风险为0.609×10-3人.次/a,符合风险标准。

The present paper aims to report the authors＇ improved method for quantitative risk-assessment method for major accidents of LNG gas station. As we know, gas-leaking has been the main kind of accidents that take place in LNG gas stations. Generally speaking, the risk-involving area of the leaking is not likely to go beyond 50 m^2. However, if the leaking gas turns to be a fire source, it may often lead to vapor cloud explosion （VCE） or boiling liquid expansion and vapor explosion （BELVE）. That is why risk-assessment has become a major research topic to find better methods for predicting or assessing the major accident categories and origins in a LNG gas station by way of analyzing the main facilities and the operating conditions or environments of LNG gas stations. It is just for this purpose that the present authors have done the following studies： （1） Trying to obtain the major accident probability due to predictable kinds of leaking by anglicizing the failure statistics in the past. This has been done through calculating or determining the leak situations or causes that may lead to the major accidents by using Monte-Carol fussy statistics method. （2） A blast wave overpressure and fireball radiation model has been chosen to predict or assess the accident consequences in close conformity with the actual characteristics of the major accidents. Based on the statistical study of the major accident category probability, the paper done detailed analysis of the leaking state and the consequence assessment models so as to find the heat radiation formulae of the fireball and overpressure due to the VCE distribution in the space. （3） After that, the scale and density of the hazards major accidents are likely to lead to in the space have been worked out in accordance with the damage consequence and risk prediction. Furthermore, the paper has also prepare a related program to define the hazard density and scope of major accidents, in which FAR and average personal risk has been chosen as risk parameter, so that the total risk for LNG gas station can be described. （4） And, finally, the quantitative risk assessment （QRA） for a LNG gas station is discussed in the paper. As a result, the paper has also worked out a probability curve of overpressure by VCE, heat flux curve by fireball radiation, IV lever risk contour as well as the risk value of total LNG gas station. The primary use of the method shows that FAR and average personal risk is 6.94 and 0.609 × 10^-3 a^-1 , which is up to the corresponding safety standards.