Reliability Analysis Of The L Station System Of The Lan-Cheng-Yu Product Pipeline

The product oil station is the core unit of oil transportation,and it undertakes important tasks such as metering,distribution and pigging.Moreover,its conveying medium-product oil has the characteristics of being flammable and explosive,and the safety problems in transportation,storage and treatment have always been the focus of attention of the state and oil and gas enterprises.In this paper,the L-station of the Lanchengyu product oil pipeline has been in operation for 17 years.There are many types of equipment in the station,the process is relatively complicated,and the equipment failure rate is gradually increasing.At the same time,the system reliability is gradually decreasing.It is imperative to study the reliability of its system.China's reliability research on the station system started late.In order to realize the system reliability analysis of the L-station of the Lanchengcheng product oil pipeline,this paper divides the reliability of the station system into the reliability of the equipment unit level and the overall system level.Two parts of reliability.For unit-level equipment,according to equipment characteristics and field data,it is divided into basic unit,specific unit and redundant unit,and adopts RBI theory,fault tree analysis method and dynamic fault tree to carry out unit reliability analysis.For the overall system level,this paper uses graph theory to construct the network topology of the station system and study the reliability of the station system.The main work of the thesis is as follows:(1)Combining the geographical location and process flow of the L-station,analyzing the failure modes and causes of the main equipment in the L-station,analyzing the reliability of the specific equipment in the L-station,and collecting the corrosion data of the field equipment.Provide data basis for reliability analysis of the base unit.(2)API581 gives the same type of failure probability as the basicunit.After analyzing the applicability of various statistical probability models,the Weibull distribution model is combined with the failure data of historical similar equipment to correct the similar failure probability.RBI technology is used to combine The 1980 corrosion point data and equipment operation status of the L-station on-site pipeline,through the equipment correction factor and management correction coefficient,calculate the failure probability of the station pipeline and other infrastructure equipment.(3)For devices that do not have the same type of failure probability in API 581 or have no historical failure data of the same type of equipment,such as receiving/sending cylinders,it is impossible to calculate the failure probability using API581 technology.These equipment units are referred to herein as specific units;The fault tree analysis method is used to analyze the failure probability of a specific unit.After the bottom event of the fault tree is evaluated by the expert scoring method,the fuzzy probability of the bottom event is solved by combining the trapezoidal fuzzy number.The D-S theory is adopted in the comprehensive expert opinion.The improved evidence-based distance-based modified evidence method is used to solve the conflict evidence,which overcomes the paradox problem of D-S theory and considers the confidence of the evidence source to be more realistic.Finally,by calculating the probability of occurrence of the fault tree top event,the failure probability of the specific device is obtained.(4)In order to improve the reliability of the station system,redundant stations are installed in the station,such as "two-purpose and one-stand" pressure reducing valves and corresponding accessories.The redundant area formed by these devices is called a redundant unit.For the reliability analysis of redundant units,the dynamic fault tree analysis method is used to transform the dynamic logic gate into the corresponding Markov chain,and the Weibull distribution function is used to improve it.Finally,the maintenance rate of the redundant unit is considered.Among them,the failure probability of the redundant unit is calculated.(5)After the failure probability of the equipment unit level is solved,the reliability analysis of the overall system of the station is performed.After analyzing the applicability of graph theory,the topological structure of the L-station system is analyzed by graph theory.After analyzing the applicability of the weighted network of graph theory,the combination of point weight network and edge weight network is completed.The graph theory analysis of the station process subsystem and the structural system solves the process system and the structural system cut set;after considering the correlation between the correlation between the equipment and the cut set,the system reliability of the station is finally obtained.The research results of this paper can supplement and improve the reliability analysis technology of the existing station system to a certain extent,and provide theoretical support for the safe operation of the product station system.