Temperatures, Pressures and Liquid Levels of Tank Cars Engulfed in Fires. Volume 2. Description of Analytical Procedure

摘要

An analytical procedure has been developed for calculating the effects of fire on a railroad tank car containing a hazardous material. The procedure was developed so that the consequences of using different conductances for the thermal insulation on the tank and different flow capacities of the safety relief valve could be determined. The analysis is used to predict various parameters which characterize the situation such as the time to failure, the amount of product remaining in the tank at the time of failure, the maximum pressure in the tank, the time to reach certain pressure levels, etc. The procedure has been used to analyze Specification 105 railroad tank cars in the pool fire environment (this assumes complete engulfment of the car in the fire). Both the upright and overturned car cases have been considered. In the overturned car case the safety relief valve vents liquid instead of vapor and the fact that the liquid volumetric flow rate is less than that for vapor must be considered. Tank cars containing the following products have been analyzed as part of this study: ethylene oxide, propane, propylene, 1,3-butadiene, vinyl chloride, monomethylamine, and propylene oxide. The results from the analyses can be used to assess the degree to which different combinations of thermal insulation systems and safety relief valves will be successful in preventing or minimizing the consequences of tank car failures. The final report has been prepared in two volumes. This volume, Volume II, describes the analytical procedure and the computer program which was used to perform the calculations. Volume I presents the results from the parametric analyses.