The analysis on calculation model of heat-wave velocity during the process of crude oil storage tank fire
The formation mechanism of boilover fire in crude oil storage tank is very complex and harmful. Heat-wave velocity is an important research topic in the boilover fire. After introducing boilover mechanism, the models of heat transfer and heat-wave velocity was built by heat transfer analysis for oil layer. Comparing the calculation results of model with the experimental data, this heat-wave speed calculation model is reasonable. Through the research, several conclusions were found: the main factors that impact heat-wave rate are the viscosity and component of oil, heat of heat-wave comes mainly from thermal radiation of flame; Emulsified water in the oil will not trigger boilover fire normally. Only the heat-wave encountered bottom water cushion at the bottom of the tank, did boilover fire take place. In practice, the heat-wave moving speed can be valued 1m/h to estimate the occurrence time of boilover. The results of this study are important for control and security of boilover fire accident.
Heat transfer mechanisms and boilover in burning oil-water systems
Abstract The vaporization of a water phase during a tank fire in a mineral oil storage tank may cause extensive damage due to the spillage of burning material and the intensified heat radiation. This phenomenon is known as ‘boilover’. The consequences of a boilover mainly depend on the heat transfer mechanisms in the oil and its ability to form a layer of uniform temperature and composition but increasing extent under the surface, i.e. the hot zone. The heat transfer mechanisms in different fuels were studied experimentally. Models were set up to describe them theoretically. The consequences of water vaporization for the different fuel types were quantified and counter-measures are proposed. The results are important for the safe layout of tank farms and appropriate fire-fighting measures.
Experimental Study On The Mechanism Of Hot Zone Formation In Open-tank Fires
Hot zones form as an effect of the boiling range of oils, for especially heavier oils. Scattered vapor bubbles are produced throughout most parts of a hot zone. The generation, ascent and growth of these bubbles cause continual and vigorous convection. The temperature, density and chemical composition of oil in a hot zone are uniform throughout the entire hot zone, both vertically and horizontally. In a tank which is less than 800 mm in diameter, formation of a hot zone depends largely on both material and diameter of the tank. Hot zone formation in a 900 mm or larger diameter tank depends only on retention of the prescribed quantity of residual fractions of distillation at the surface temperature of the burning oil as determined by a distillation curve. Rate of conversion to a hot zone has a close relationship to the complicated oscillations accompanying the transfer of heat and mass through the interface.