基于海洋平台碰撞事故的LNG船泄露风险评估

发布时间：2019-03-10 21:03

【摘要】：在航行过程中，船舶发生海损事故是难免的。在猛烈的冲击作用下，LNG船舷侧结构遭受严重损伤，引发LNG泄露事故。泄露的LNG在空气中迅速形成重气云团，在燃烧爆炸范围，一旦遇到点火源，即刻发生燃烧，，极有可能升级为火灾、爆炸事故，进一步加剧船体结构的破损，不仅会对人员及设备的安全构成威胁，还对环境形成污染。对LNG船进行风险评估工作，可以科学预测事故发生的概率以及事故产生的后果。在船舶与海洋工程领域，定量风险评估技术越来越受到人们的关注，主要是因为该技术能深刻反映风险本质，对提高LNG船营运过程中的安全性具有重要意义，为设计降低LNG船泄露的可能性提供了较为可靠的理论依据。本文在风险评估理论的基础上，对风险识别进行了简单介绍；对计算事故发生率的方法进行探讨分析，并做相应的计算；在研究故障树(FT)分析方法的基础上，引入了贝叶斯网络(BN)定量分析导致碰撞事故发生的人为原因。本文还对LNG船舷侧采用复合夹层结构来增强其耐撞性进行了研究，提出了降低风险后果的措施；最后将模糊综合评判法(FCE)与LNG船泄露风险评估相结合，实现了与海洋平台碰撞LNG船泄露的模糊综合评判。本文主要工作及结论如下： (1)分析了在海洋工程风险评估领域目前国内外研究进展，阐述了风险评估的理论基础，从个人风险、社会风险、环境风险三方面进行风险衡量，同时探讨风险可接受准则。 (2)对风险识别进行了简单的介绍，比较了各种常用风险评估方法的优缺点，分析事故后果对人员、设施的产生的影响，提出了控制风险的措施。 (3)基于二项分布预测了LNG船年度碰撞事故发生概率；参考DNV过往船只与海洋平台发生碰撞风险的分析方法，利用程序计算了LNG船处于不同角度时与海洋平台发生碰撞的概率，发现LNG船碰撞事故发生的概率随角度的增大呈指数增长，计算结果与统计资料基本一致。同时在研究故障树(FT)分析方法的基础上，引入了贝叶斯网络(BN)定量分析导致碰撞事故发生的人为原因，并提出了降低事故后果的措施。 (4)本文提出了一种复合夹层结构形式，用该结构替代LNG船原有的双舷侧结构，并借助非线性有限元分析软件MSC.Dytran对此进行模拟计算。与传统的钢结构相比，复合夹层结构优势比较明显，如：结构的承载能力、抗冲击能力好，具有优良的耐撞性能、结构形式简单、结构本身较轻等，是降低风险后果的有效措施之一。 (5)在模糊综合评判理论的基础上，运用层次分析法，引入泄露气体量、LNG特性、天气海况、LNG船状及人员状况(距风险源距离)等风险影响因素，计算了各影响因素(参数)的权重系数，对LNG船泄露风险的进行模糊综合评判。
[Abstract]:In the course of sailing, it is inevitable that there will be an average accident on the ship. Under the severe impact, the side structure of LNG ship suffered serious damage, causing LNG leakage accident. The leaked LNG rapidly forms heavy gas clouds in the air. In the range of combustion and explosion, once a source of ignition is encountered, combustion occurs immediately, which is likely to escalate into a fire and explosion accident, thus further aggravating the damage of the hull structure. It will not only threaten the safety of personnel and equipment, but also pollute the environment. The risk assessment of LNG ship can predict the probability of accident and the consequence of accident scientifically. In the field of ship and marine engineering, quantitative risk assessment technology has been paid more and more attention, mainly because it can reflect the nature of risk deeply, and it is of great significance to improve the safety of LNG ship operation. It provides a reliable theoretical basis for the design of reducing the possibility of LNG ship leakage. Based on the theory of risk assessment, this paper briefly introduces the risk identification, discusses and analyzes the method of calculating the accident incidence, and makes the corresponding calculation. Based on the study of fault tree (FT) analysis method, Bayesian network (BN) is introduced to quantitatively analyze the man-made causes of collision accidents. In this paper, the use of composite sandwich structure on the side of LNG ship to enhance its crashworthiness is also studied, and the measures to reduce the risk consequences are put forward. Finally, the fuzzy comprehensive evaluation method (FCE) and LNG ship leakage risk assessment are combined to realize the fuzzy comprehensive evaluation of LNG ship leakage in collision with offshore platform. The main work and conclusions of this paper are as follows: (1) the research progress in the field of marine engineering risk assessment at home and abroad is analyzed, and the theoretical basis of risk assessment, including individual risk and social risk, is expounded. Environmental risk three aspects of risk measurement, while exploring the risk acceptable criteria. (2) the paper briefly introduces the risk identification, compares the advantages and disadvantages of all kinds of commonly used risk assessment methods, analyzes the impact of the accident consequences on the personnel and facilities, and puts forward the measures to control the risk. (3) based on binomial distribution, the probability of annual collision accident of LNG ship is predicted. Referring to the analysis method of collision risk between DNV ship and offshore platform, the probability of collision between LNG ship and offshore platform at different angles is calculated by program. It is found that the probability of LNG collision increases exponentially with the increase of angle, and the calculated results are basically consistent with the statistical data. At the same time, on the basis of studying the fault tree (FT) analysis method, the Bayesian network (BN) is introduced to quantitatively analyze the man-made cause of the collision accident, and the measures to reduce the accident consequence are put forward. (4) in this paper, a kind of composite sandwich structure is proposed, which is used to replace the original double-side structure of LNG ship, and it is simulated and calculated with the help of nonlinear finite element analysis software MSC.Dytran. Compared with the traditional steel structure, the composite sandwich structure has obvious advantages, such as the bearing capacity of the structure, the good impact resistance, the excellent impact resistance, the simple form of the structure, the lighter structure itself, and so on. It is one of the effective measures to reduce the risk consequences. (5) on the basis of fuzzy comprehensive evaluation theory, using analytic hierarchy process (AHP), risk factors such as leakage gas, LNG characteristics, weather and sea conditions, LNG ship shape and personnel status (distance from risk source) are introduced. The weight coefficient of each influencing factor (parameter) is calculated, and the fuzzy comprehensive evaluation of the leakage risk of LNG ship is carried out.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：U698

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