油罐火灾沸溢发生时间预测模型

油罐火灾发生沸溢具有很大的危险性,而沸溢时间的准确预测是目前的一个技术难题。笔者结合宽沸程油品油罐火灾沸溢实验,对油层内部传热过程进行详细分析,认为油罐火灾沸溢事故可近似地看作一无内热源、常物性的非稳态传热问题,其过程包含油水界面不参与换热和参与换热的两个阶段。建立了油罐火灾沸溢发生时间预测模型,对两个不同阶段,分别进行理论分析和数值方法进行求解,并同实验数据对比。结论可信,误差较小,为沸溢机理探讨研究和油罐沸溢火灾的扑救提供了参考依据。计算表明:燃烧速度和油罐底部水层厚度对沸溢时间的影响很大,而降低罐壁温度并不能有效地延迟沸溢的发生。

Time Predicting Model for the Onset of Boil over in Tank Fire

Occurrence of boil over in tank fire is very dangerous. To accurately predict the time of onset is a technical difficulty. Referring to a boil over experiment in tank fire of wide distilling range oil, the process of heat transfer inside the oil layer was analyzed in detail. It was found that the boil over incident could be considered as a problem of unsteady heat transfer with constant material property without inner heat source. The process could be divided into two phases, i.e. oil/water interface not participating in heat transfer and participating in heat transfer. A new onset time predicting model for the boil over in tank fire is established, by which theoretical analysis and numerical calculation were conducted for two different phases. Results were compared with the experimental data. The conclusion is reliable with minor error which might provide the criteria for the study of the mechanism and fighting measures of boil over. The calculation results revealed that the buming speed and the depth of water layer beneath the oil have great impact on onset time of boil over, while lowering the temperature rare of the tank wall could not effectively delay the onset of boil over.