A small-scale experimental study on the initial burst and the heterogeneous evolution process before CO2 BLEVE

The sudden rupture of a vessel containing liquefied carbon dioxide (CO2) can generate a boiling liquid expanding vapor cloud explosion (BLEVE). The entire evolution process and mechanism of CO2 BLEVE has not been fully characterized, and its influencing factors have not been systematically examined. In this study, the ejection process and microphase change process in the vessel were recorded by a high-speed camera. Within 20 ms, the pressure peaks surpassed the initial values and were considered to be the initiation of a sequence that generated a CO2 BLEVE under certain conditions. In addition, a critical relief caliber with a diameter of 8 mm was observed under the initial burst pressures of 3 and 5 MPa. This critical relief caliber is essential for risk control and management. About 52 ms after the rupture, a heterogeneous nucleation center was formed in the liquefied CO2 in the vessel. Subsequent nucleation center extension and swelling generated another pressure peak. The pressure peak did not surpass the initial pressure value. However, this phenomenon did not eliminate any possible connections between the heterogeneous nucleation process and the CO2 BLEVE. If the conditions had been proper, the explosion could have happened.