Studies On The Reconstruction Of Oil Boilover Fire And Control Technology

Boilover is one of the most dangerous on oil tank fires. Boilover is a very complicate process, which has the character of great dangerous and difficult to control, but it is not been look as an important problem. The reason of boilover is unkown for our, the methods of prevent boilover formation is unsuccessful. So, study the mechanism and the formation condition of boilover is important. We analysis the complex process of heat and mass transfer, and especially study the parameters on the each stage of boilover fire, which can provide the correct methods of prevention the boilover and decrease the loss of boilover. In order to gain the main propose. We have done the below works:By the experimental study the character of oil which has boilover phoneme on the process of combustion. The concept of boilover triangle is established, and the oil with the condition of boilover triangle can has boilover phoneme on the process of combustion. The main analysis instruments are GC-MS and TGA. The influence of the water content of oil, boiling range and viscosity for boilover was analyzed.The small-scale boilover fire simulation experiment bench was built, which can real-time surveys the characteristic parameters of boilover. The characteristic parameters include burning velocity( linear burning rate and mass burning rate),heat release rate, flame temperature, radiation and flame height, which were investigated in the combustions of mixed crude oil, mixed oil(kerosene and lubrication oil) and diesel oil on quasi-steady combustion, pre-boilover and boilover stage. Mutations were found in those parameters, the values of burning velocity and heat release rate became times to several decuple of those mean values on boilover stage. Using the non-contact infrared thermometer analyzes the flame temperature field on each stage of boilover. The thermal structure of oil and water layer and factors which can influence the boilover formation and intensity were studied. The range of 110℃-130℃is the characteristic temperature range of boilover. We utilized our program calculated the change scope of flame height, and flame pulsation frequency. Based on the experimental data, the heat wave velocity, boilover formation time and the radius of boil-over were predicted. The solid flame model was used calculated the thermal radiation on quasi-steady burning phase. The calculation values and the experimental values were compared, and we found the calculation values are consistent with experimental values. The flame shape, flame temperature and fire area change when boilover fire forms. Those changes can lead to the mutation of thermal radiation. Based on the calculation of radius of boilover, point source flame model was used to calculate the thermal radiation on boilover stage. We calculated the thermal radiation on boilover stage. Lastly, we used the simulation principles of scale establish the relation between the small-scale and large-scale boilover.The software of FDS was used to simulate the large-scale boilover. Firstly, we proved the feasibility of FDS on the simulation of quasi-steady combustion stage. We used the software of FDS simulate the flame temperature, velocity field and flame thermal radiation. Especially for the main dangerous of flame thermal radiation, the distribution of flame radiation intensity on horizontal and vertical orientation was gained. The principal of thermal radiation destroy was used to determine the safety distance when boilover happens.Experimental study the oil-water interface with high-speed photography and experimental study the formation of bubble and the accumulation of bubble were carried out. The formation of bubble is proved is the reason of flame height change and the accumulation of bubble is the reason of boilover formation. The accumulation of bubbles can cause the micro-explosion of steam, which can make the pressure of oil-water interface increase. The increase of pressure can cause the boilover formation. Boilover fire is a mutation harmfulness phenomenon. The prevention of boilover is a difficult problem. Based on experimental study of boilover mechanism, the small-scale tank boilover fire prevention experiment platform was built to resolve the problem. We study the prevention methods of boilover. The prevention methods can divided into initiative and passive prevention methods. The passive prevention method is measure the tank wall temperature with the IR thermal field diagnosis method. According to temperature of tank wall and the heat zone temperature, predict the boilover formation. The second method of passive prevention method is using the zeolite to prevent the super-heat water acute boil. The initiative prevention method is using serpentinepipe cooling system apply on boilover prevention. The temperature of oil layer,oil-water interface, water layer and radiation proved the serpentinepipe cooling system can reduce and prevent the harmfulness of boilover. The small-scale tank boilover fire prevention methods can provide theoretical foundation for the prevention of large-scale tank boilover fire.