Theoretical And Experimental Study On Dynamics Process For Accident Of Release

There are amounts of hazardous materials in process industries. Once thesehazardous materials were released due to accidents, they could enter into atmosphereand do harm to human beings and environment. So it is very important to preventaccident of release and directing rescue in emergency to study dynamic process ofaccident of release for hazardous materials.The grave and typical accidents of release happened in between 1949 and 1999in chemical plant in China were analyzed statistically. According to accidentfrequency and the number of people killed or injured, the following hazardousmaterials should be controlled firstly: liquefied chlorine, liquefied ammonia, liquefiedpetroleum gases, chloroethylene, benzene, methylamine, carbon monoxide andsulfureted hydrogen. Seven factors affecting the process of accident of release weresummarized and sixteen release modes were established.Pool spreading and evaporating processes were researched based on dynamics.According to mass conservation law, they were combined with each other organicallyand the dynamic evaporation model was established. In addition, heat transfer in theprocess of evaporation was analyzed in detail, and the heat and mass transfer couplingmodel was developed. Moreover, an evaporation model based on boundary layertheory was established. In order to research evaporation mechanism, wind tunnelevaporation experiments about pure liquids (such as benzene, toluene and ethanol)and multicomponent liquids (such as benzene-toluene solution, benzene-ethanolsolution, naphtha and crude oil) were conducted. The results indicated that theevaporation of pure liquids and solutions contained two components were controlledby boundary layer evaporation. And the evaporation of naphtha was regulatedincompletely by boundary layer evaporation. As wind speed or evaporation areaincreased, the evaporation of naphtha tends to be regulated by basic evaporation. Andthe evaporation of crude oil was not regulated by boundary layer evaporation, but bybasic evaporation. The evaporated mass varied with t for pure liquids, t0.7 for naphthaand t0.55 for crude oil. As for the benzene-toluene solution and benzene-ethanolsolution, the relationship between evaporated mass and time varied with componentsand mole fraction. Based on experimental results, following conclusions were drawn: i⑴ The more similar of the evaporation capability or mole fraction of the twocomponents, the easier the relationship between evaporated mass and time took onpower law. ⑵ The higher or bigger of the wind speed or pool area, the easier therelationship between evaporated mass and time took on power law. Based onexperimental results, a new experiential model predicting evaporation rate wasdeveloped. The error between the evaporation rate predicted by the experiential modeland experimental results was less than that between Mackay & Matsugu model andthe experimental results. In order to study the effect of solar radiation intensity onevaporation, outdoor experiments were done. The results indicated that the effect ofsolar radiation intensity on evaporation was very great and it should be consideredduring the evaporation calculation. In this situation, the evaporation rate predicted bythe new experiential model and Mackay & Matsugu model were compared withexperimental results. The results show that Mackay & Matsugu model should be usedwhen solar radiation intensity was strong. The average error of evaporation ratepredicted by Mackay & Matsugu model was less than 16%. The heat and masstransfer coupling model was validated based on experimental results. The resultsshow that the model could predict the evaporation rate and liquid temperature welland truly. Moreover, the theoretical model based on boundary layer theory was alsovalidated. The predicted evaporation rate was compared with experimental results andthe evaporation rate predicted by Mackay & Matsugu model, GRAY model, BAUmodel, SUBTEC model, EPA model,...