The Dynamic Risk Transfer Model Of Refining System Considering Delayed Effect

Refining process is a typical high-risk system.The composition of complex system and behavior relations has a high degree of correlation and strong coupling between the environment.The system fault behavior has the characteristics of diversity,randomicity and emergent properties.Therefore,failure or deviation of single equipment or processes in the system is easily produced by system of interdependence and restricting relationship.Fault chain effect can be easily caused and the harm is much more significant than the single fault events that caused.In view of this,based on the characteristics of production process of petrochemical system,combined with the problems in field application,field test and simulation,a new method is proposed.The paper conducts the following works:(1)Aimed at the modeling method of chain effect is mainly based on expert knowledge of brainstorming and good grasp of researchers on the process and principle of system,which is not conducive to the inexperienced staff.In view of this,an analysis method based on chain relational matrix system in high-risk fault chain effect is proposed.The method based on the principles of mass and heat balance to analyze fault chain effect of system,and then fault propagation path of the system can be acquired.The effectiveness of the method is verified by regenerator explosion scenario and fractionating tower accident scene of FCCU.The results shows that the fault propagation paths of regenerator explosion accident are 30 and fractionating tower rush accident of tower failure are 9.(2)Due to the low accuracy of existing delayed effect analysis method for refining system,method based on fault timed Petri net in the refining process of fault propagation delayed effect analysis is proposed.According to the characteristics of the refining system,two fault propagation delay time algorithm,including single fault input mode propagation and multi fault input propagation mode is proposed,which is used to estimated the time of refining system under a perturbation until to the accident occured.The effectiveness of the method is verified by regenerator explosion scenario and fractionating tower accident scene of FCCU.The results shows that compared with the simulation,the average relative error is 6.8% of the proposed method,which is 9.5% lower than the traditional method.(3)For the intervention of system protection layer on the system risk,the real-time degradation of system and ductility of failure propagation has not been considered by traditional petrochemical system risk assessment method,which lead to the evaluation results in the lack of accuracy,and deviating from the actual condition.As a result,the method considering response of protective layers for systematic risk dynamic transfer in refinery process is proposed.Protective layer for dynamic mechanism and three-dimensional risk matrix is set up based on fuzzy Petri nets,which can help to acquire dynamic risk rank and analyze the risk trend of refining system under the influence of protection layers and fault propagation.The effectiveness of the method is verified by fractionating tower accident scene of FCCU.Compared with the traditional method,the method incorporates the possibility and severity of accident occurrence,and the ductility of failure propagation,which is more comprehensive.