Quantitative Risk Assessment Theory And Its Application Of Petrochemical Plant Accident

Lot of inflammable,explosive,toxic and harmful chemicals are involved in the production process of petrochemical industry,especially in the harsh conditions of high temperature and high pressure,once the accident occurs,the consequences are extremely serious.Therefore,the current situation of the accident risk assessment for the petrochemical plant is discussed,and its quantitative risk assessment theory and actual application are systematically and deeply researched in the dissertation.(1)Advantages and disadvantages of the fault tree analysis are discussed,and the calculation method for the basic event importance is analyzed.In view of the shortage of the probability expression form of the accident tree,the GSPA theory is introduced,and the expression form of the two state fault tree based on the GSPA is proposed,and the basic structure importance,the probability importance and the relation importance of the accident tree are given based on the GSPA.Comparing the accident tree with the probability form and the contact degree form,the former is only the special form of the latter,and the latter is the general expression of the former.(2)The application status of Bayesian network in system risk analysis is expounded,the calculation methods of the importance degree,probability importance and key importance of the node structure are analyzed;the expression form of Bayesian network is proposed based on GSPA,and the basic structure importance,the probability importance and the relation importance of the Bayesian network node based on GSPA are gave.Comparing the accident tree with the probability form and the contact degree form,the special form of the former is only a special form of the latter,and the latter is the general expression of the former.(3)The types of Bayesian network reasoning are analyzed by exact reasoning and approximate reasoning,and the existing precise reasoning process and the process of approximate reasoning and the advantages and disadvantages are discussed,and the accurate reasoning method of hierarchical module elimination and hierarchical module bucket elimination are proposed.(4)The differences of the existing domino definition are analyzed,and the domino characteristics and the initial type of accident that triggers the domino effect in the petrochemical plant accident are analyzed;In view of the different types of initial accidents that trigger the domino effect in the petrochemical plant accident,the corresponding model and the calculation method of domino effect triggered by the heat load and the blast shock wave load and explosive fragment ejection are discussed.(5)In view of the existing problems which are the lack of the research on the mutual influence of domino effect between the targets at all level in the analysis of the domino effect in the existing petrochemical plant accident,the advantages of BN which uses the conditional probability to describe the logical relationship between events are fully excavated by BN,and the domino effect model of the petrochemical installation accident domino effect is studied,which solves the logical relationship between the targets at all levels in the process of Domino effect transmission;Using the GSPA theory whose advantage is to solve the uncertainty problem,the domino effect model of the petrochemical plant accident is proposed,and the happening trend of the Domino effect from three angles is analyzed based on the same character,difference and antagonism,which is more scientific to describe the accident domino effect.(6)In view of the domino effect of petrochemical plant accident,,combining the characteristics of petrochemical plant,the optimistic and the pessimism potential of generalized set pair of BN topological structure are proposed by the advantage,which reflects the BN topology structure of petrochemical plant accident from different angles,such as optimism and pessimism.(7)In view of the deficiency of "death,heavy injury and direct economic loss as the grade of accident" as a judgment principle,the method of determining judgment index coefficient of accident grade is proposed:linear piece wise function model and nonlinear piece wise function model in which the accident after multiple index coexistence cases are gave.The calculation method of the comprehensive coefficient of the fruit and the judgement criterion of the accident grade are gave,which realizes the purpose to realize the balance of the accident scene rescue,the accident scene cleaning,the accident treatment,the accident casualty and the attention of the relevant enterprises and the government to the accident.(8)In view of the existing quantitative risk calculation methods,such as "small accident probability of chemical equipment,serious accident consequences" and"large probability of accident in chemical equipment,minor accident",a variable risk characterization method is proposed,which further enriches the theory of risk assessment.(9)From accident probability and the consequence,accident risk management and control barrier model of petrochemical plant based on BN-LOPA is studied,and two kinds of risk degree,which are difficult to solve "small accident probability of chemical equipment,serious accident consequences" and "large probability of accident in chemical equipment,minor accident consequences",accident risk variable management and control barrier model of petrochemical plant based on BN-LOPA is presented.When the parameters are 1,latter is former,which indicates that the former is the special case of the latter.