An experimental study on the temperature dependence of CO2 explosive evaporation

The need for transportation and storage of CO2 in bulk quantities is likely to increase in the near future. The handling of CO2 on such scale gives rise to a number of technological challenges and safety aspects. The accidental rupture of a vessel containing liquefied CO2 may lead to a Boiling Liquid Expanding Vapour Explosion (BLEVE). Whether explosive evaporation of liquefied CO2 is also possible at storage temperatures below the homogeneous nucleation temperature 271 K (-2 degrees C) is unclear. This article describes the results of 12 experiments with 40 L CO2 cylinders at various temperatures to investigate the temperature dependence of explosive evaporation. The cylinders were opened with linear shaped charges to simulate a near instantaneous rupture, and blast was measured at various locations. The observed blast could be clearly attributed to explosive evaporation. The results show that below the homogeneous nucleation temperature, BLEVE blast does not disappear abruptly, but instead follows a gradual decay. Predictions with a numerical BLEVE blast model overestimate the observed blast peak overpressure and impulse, but qualitatively show a similar behaviour. The energy lost by the acceleration of the cylinder parts is a possible reason for overestimations of the model. The consequence of the test results is that for accident scenarios with CO2 at low temperatures a BLEVE should not be neglected in hazard assessments. Future large scale bulk storage will take place at a 105 times larger volume than the cylinders applied in the current small scale experiments. We expect that the blast-reducing effects of a tank shell will disappear at such scale. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 241381. (C) 2013 Elsevier Ltd. All rights reserved.