Study On Risk Assessment Of Crude Oil Tanks Based On Cloud Theory

With the continuous development of the world economy,the social demand for oil and gas is increasing.The fact of energy shortage is becoming more and more obvious,and energy security is also paid more attention.As an important equipment of oil storage and transportation system,storage tank covers a large area,and having a variety of equipment.The storage and transportation medium is inflammable,explosive,high-pressure and toxic,which makes the storage tank management difficult.Failure of storage tank will cause serious economic losses,life hazards and environmental pollution,and maintenance costs are also very high.Therefore,how to scientifically and effectively carry out storage tank risk assessment has become the most important part of storage tank integrity management.In this paper,the safety of crude oil storage tanks is taken as the research object,and the cloud inference method is used for risk assessment.As a relatively new mathematical tool,cloud model can not only consider the randomness of the evaluation object,but also consider its fuzziness,and realizing the transformation between qualitative concepts and quantitative values.In the process of risk assessment of crude oil storage tank,cloud model is introduced to reflect the discrete degree of evaluation data in the form of cloud map.Based on the analysis of the structure of the storage tank,the crude oil storage tank is selected as the evaluation object.After identifying the hazard sources and analyzing the fault tree,the basic failure factors are obtained,and the risk evaluation index system of the crude oil storage tank is established.Combining with cloud theory,the weights of indicators are determined by combining subjective and objective weighting methods,objective weights are determined by entropy weighting method,subjective weights are determined by heuristic expert scoring method based on cloud model,and subjective weights are checked and revised by Bayesian feedback cloud model.The multi-level risk evaluation index system is studied.Combining the characteristics of multi-level risk evaluation index,the floating cloud model and comprehensive cloud model are introduced.Combined with the improved comprehensive cloud technology,a multi-level multi-index cloud gravity center evaluation method based on improved comprehensive cloud technology is proposed.Taking a crude oil tank in a refinery as an example,the floating cloud model of the index layer and the comprehensive cloud model of the target layer of the crude oil tank are established by constructing the risk evaluation index system,and the risk evaluation grade of the crude oil tank in the refinery is determined.The evaluation results of the cloud model are verified by the fuzzy comprehensive evaluation method.According to the establishment of the risk evaluation index system for crude oil storage tank,the calculation of combination weights and the risk evaluation of cloud model,the following conclusions are drawn:the first level index of the risk evaluation index system for oil storage tanks is corrosion factor,equipment factor and other factors,and their risk evaluation status is "general","general" and "slight".There are five corrosion factors.Secondary evaluation indicators,equipment and facilities factors have three secondary evaluation indicators,and other factors have four secondary evaluation indicators.The objective weight values of risk indicators are determined by the entropy weight method,and the subjective weight values of each index are determined by the expert scoring method of cloud model.According to the difference-driven method,the combined weight values of each risk evaluation index are calculated,and the combined weight values of each risk evaluation index are determined by the analytic hierarchy process.The validity of the combination weight is confirmed by re-validation.According to the index layer floating cloud model,the risk assessment level of each level index is as follows:corrosion factor and equipment and facilities factor are in the "general" and other factors are in the "slight".The weight similarity between the system cloud gravity center vector and the general cloud gravity center vector is the greatest,and the distance between the system cloud gravity center vector and the good cloud gravity center vector is the smallest,and the tank risk assessment status is at the "general" level.According to the results of tank risk assessment,the management and preventive measures of production operation,alarm management,equipment and facilities management and personnel management are put forward respectively.