Release mechanisms and waves interaction during liquified CO2 depressurization in a double-membrane conical vessel

Abstract

An unintended release of liquid CO2 during its transport results in depressurization with rapid phase transitions, evaporation, and expansion. Such progression may lead to catastrophic container failure with boiling liquid expanding vapor explosion (BLEVE). Therefore, to design safe CO2 transport structures, it is essential to investigate the processes associated with CO2 depressurization. This paper presents a new test rig combining a divergent cross-sectional test vessel with a double-membrane rupturing system. The rig is designed to study the effect of diverging cross sections on phase transition rates and wave propagation during liquid CO2 depressurization. The apparatus has a high-pressure (HP) conical-shaped vessel and a medium-pressure slip-on flange section (MPS) that separates two membranes. The main contribution is examining rupturing methods and subsequent generated waves behavior to evaluate the installation performance. Pressure histories and high-speed video recordings were utilized to analyze the wave pattern and membrane rupturing mechanisms by increasing or decreasing the MPS pressure. A comparison of these two techniques demonstrates that decreasing the MPS pressure requires an extended period between diaphragms rupture and has a lower evaporation wavefront velocity than increasing the MPS pressure. Increasing the MPS pressure method has better reliability and simplicity and provides a more controllable operating system. Increasing the MPS pressure avoids a complicated wave pattern in the test section and prolonged rupturing time.ArticleHighlightsThe conical vessel with a double membrane shows the wave structure during saturated liquid CO2 depressurization.During liquified CO2 decompression, the double-membrane rupturing sequence affects the expansion wave pattern and evaporation rate.By decreasing the medium-section pressure, slower wave propagation and complex reflected waves are observed in the test section.