Study On Computational Method And Regularity Of Vapor Cloud Explosion On Offshore Platform

Risk of flammable vapor cloud explosion on offshore platforms has gradually emerged with the development of offshore oil and gas resources.Safe production of offshore engineering has put forward new requirements for the prevention and control of explosion,while the prediction method and influence law of vapor cloud explosion is a key issue.Based on this,this paper studies the computational and prediction method of flammable vapor cloud explosion on offshore platforms and the influence law of key factors,providing theoretical guidance for the safety prevention and control of vapor cloud explosion on offshore platforms.Firstly,the explosion principles of flammable gas,as well as explosion conditions,explosion mode,explosion development process,explosion damage principle and damage criterion are studied,meanwhile,the key parameters such as flame speed,explosion overpressure and overpressure time history curve are analyzed.Secondly,three methods for predicting flammable vapor cloud explosion are explored and compared,which are TNT equivalent method,TNO multi-energy method and CFD numerical simulation method represented by FLACS.Analysis and calculation are carried out under the same explosion conditions,suggesting that TNT equivalent method and vapor cloud explosion law deviate greatly,and TNO multi-energy method is only suitable for the initial conservative qualitative prediction.They have the disadvantages such as fewer influencing factors,single index of explosion consequence and isotropy of calculation results,while CFD numerical simulation method has obvious advantages in these aspects.In order to study the law of vapor cloud explosion in typical structures of offshore platforms,a model of vapor cloud explosion was established based on CFD method,and a series of explosion experiments of foreign MERGE projects were used to verify the model.The highly consistent calculation results were obtained and the validity of the model was verified.Finally,fuel concentration and structure arrangement are deeply studied by analyzing the influence of vapor cloud explosion for the typical structure of offshore platforms where methane is selected as explosive fuel.The key indices of vapor cloud explosion under different concentration and different structure arrangement are calculated respectively.Results show that the maximum explosion damage concentration of methane-air homogeneous mixture is 10%,the explosion effect of vapor cloud explosion is sensitive to the structure arrangement,and structural obstacles with uniform spacing leads to the most serious explosion effect.The influence curve of fuel concentration on gas explosion is obtained,and the law of arrangement of structural obstacles influencing on methane explosion is summarized.