Research And Application Of Control Effect Of Safety Barrier In Steam Cloud Explosion Accident

The petrochemical industry experiences the accident of Vapor Cloud Explosion mostly and VCEs becomes a major hazard in this kind of industry causing large scale and serious accident consequence. With the development and enlarging scale, the characteristics are more outstanding. So, it is still a focus that enterprises and researchers should pay attention to and study on.Researchers have studied VCEs from the aspects of mechanism, impact factors, frequency, consequence to prevent and control VCEs in engineering practice; Based on accident lessons and theory research, some relevant standard specifications have been published. So that safety barriers can be set up by technology and manageable means to control VCEs. So how about the control effects and whether there is a need to improve safety barriers also become an issue and a research direction that we should focus on.Making "control effects of safety barriers applied to VCEs" as a study object, Energy Accidental Release Theory, Energy Model and Accident Causal Chain Theory of Heinrich are studied to analyze their functions in accident causal analysis and safety barriers setting up; To supply model construction with technology methods, comparisons are made among methods and appropriate methods are chosen, based on the purpose of the mode; Researching the requirements of VCEs happening and the definition, function and classification of safety barriers, main factors causing VCEs are analyzed and safety barriers applied in engineering practice are summarized. On the foundation of above research, mode of control effects evaluation are constructed taking use of Bow-tie, TNT equivalent, overpressure criteria and risk matrix. By this mode, hazard and required factors resulting in VCEs are got including probability and risk index. Then, the indexes are analyzed to figure out controlling degree of safety barriers. So that instructional advice can be proposed in setting up and improving safety barriers.Choosing a new propane tank farm of a certain gas company in Tianjin as an example, inherent risk of substance, leaking mode, ignition source, leaking point and mechanism causing accident are analyzed to get VCEs hazard. Making major rupture as the top event, bow-tie diagram are made up.Then, the probability of VCEs is got and decreased to 10-6/a under the effect of safety barriers. The VCEs becomes a rare accident, indicating safety barriers performance very well in controlling probability of accident; Making factory-out road, office zone, gas filling station, liquefied gas as analyzed objects, the consequences of above zones are got. Then risk indexes are got combining with probability. The risk of all zones are decreased from "High", to "Comparatively high". It demonstrates that safety barriers take effect, but not very obvious because of the severity of consequence. So, there is still a need to take measures to improve safety barriers further in controlling consequences.