Abstract: In order to reasonably determine VCE defense load in multiple scenarios of complex petrochemical process, a quantitative assessment method was established based on risk acceptance criteria and blast resistant and defense requirements. Firstly, leakage units were divided according to dangerous process flow, and explosion frequency was calculated. Then, based on multi-energy method from Netherlands Organization for Applied Science, overpressure and duration of 720 potential explosion scenarios were calculated. Finally, VCE defense load of a petrochemical plant control room was determined quantitatively depending on two proposed criteria. The results show that a reasonable load should simultaneously satisfy risk acceptance criterion of cumulative frequency at 1×10^-5 to 1×10^-4 times/a and maximum stability criterion of explosion overpressure. Explosion scenarios, frequency, volume of blocking area and distance away from explosion source are key variables affecting VCE load. The proposed method can filter out impacts of high consequence and low probability scenarios on final VCE defense load, and meanwhile avoid randomness of its calculation results caused by discrete selection of scenes.

Key words: vapor cloud explosion(VCE), blast resistant and defense load, quantitative risk assessment, explosion frequency, risk criterion