Study On Explosion Risk Assessment Of Tetrafluoroethylene Metering Tank

With the rapid development of the chinese fluorine chemical industry,its hidden safety issues have become a topic focus.There are many flammable and explosive hazardous chemicals in the fluorine chemical industry.The layout of equipment in the plant is complex and the distances are close.Once an explosion accident occurs,it is easy to cause a chain reaction of surrounding equipment and cause serious consequences.In this thesis,the tetrafluoroethylene(TFE)metering tank and its surrounding scene layout of a fluorine chemical enterprise was chosen,and the explosion risk assessment research was carried out to provide a reference for the engineering application of explosion risk analysis in the fluorine chemical industry.Based on the qualitative analysis of the fire and explosion risk of the TFE metering tank,the Dow chemical fire and explosion risk index method(F&EI)was used to calculate the hazard levels of the TFE metering tank before and after compensation for safety measures.The results show that the danger level after compensation for the safety measures of the TFE metering tank can be reduced to the acceptable level.This method can provide a reference for reducing the danger level of the fluorine chemical plant equipment.The fuzzy fault tree analysis(FFTA)method was used to analyze the cause of the explosion of the TFE metering tank leaking vapor cloud,and the probability of the TFE metering tank leaking vapor cloud explosion was calculated.According to the analysis results of the importance of basic events,it is concluded that the five main events of TFE vapor cloud explosion are,in order,the leakage of TFE reaching the explosion limit,the sudden power failure of the main control UPS,the static spark caused by the excessive flow of TFE,and the factory quality defects such as lack of timely ventilation inside and valve and meter manholes on the TFE metering tank.FFTA can be used to effectively identify potential safety hazards and eliminate or reduce system operation risks for the personnel of fluorine chemical enterprises in the plant area.Based on the study of the explosion hazard of the TFE metering tank,the ALOHA software was used to study the law of the explosion of the TFE vapor cloud.The consequences of the vapor cloud explosion of the continuous leakage and instantaneous leakage of the TFE metering tank under different wind speeds and leakage rates were discussed.The research results show that the lower the environmental wind speed and the greater the leakage of TFE,the greater the impact on the explosion of the TFE vapor cloud.The leakage of TFE is the key factor that determines the consequences of the vapor cloud explosion.According to the annual average wind speed of the fluorine chemical company,the safe distance after the vapor cloud explosion occurred when the TFE metering tank leaked.The simulation results of ALOHA software are more in line with the actual situation for the engineering application of fluorine chemical explosion risk analysis and evaluation by comparing and analyzing the results of shock wave overpressure calculated by ALOHA software simulation calculation and TNT equivalent method.The expansion path of the explosion domino accident was obtained combining the ALOHA and the expansion threshold of the steam cloud explosion shock wave,and the expansion probability of the domino accident was obtained by using the shock wave expansion probability calculation model.A bayesian network model of the domino effect was established using the Ge NIe software,and the probabilities of the first,second,and third level domino scenes were obtained.The results show that the occurrence probability of the domino scenes gradually decrease with the upgrade of the domino scene.The most likely expansion paths for the first,second,and third level explosion domino scenes are identified as A→D,A→D→F,A→D→F→G using the evidence reasoning ability of bayesian networks.The personal risk in each domino scene is analyzed,and the analysis result of the domino effect is verified through the human vulnerability model and the domino effect personal risk calculation model.