Gas to liquid transfer enhancement during hydrate crystallization: Case study of CO_2 hydrate for cold storage and transport

摘要

Secondary refrigerants, like ice slurries, are already used for industrial application, but theirgeneration requires mechanical processes (scraping or brushing surface exchangers). CO_2hydrates slurries were classically obtained in a stirred reactor, by gaseous CO_2 dissolution insideliquid water and cooling process.In the present work, an original set up was developed in order to measure in real time and in situthe dissolved CO_2 amount in the liquid phase during crystallization process thanks to the FTIRATRmeasurements.Results on this device allowed to quantify crystallization driving force, related to supersaturation,and to focus on the crystallization limiting step, in particular to determine whether or not it is gas toliquid diffusion. Some parameters were tested as stirrer type (propeller, Rushton turbine with andwithout hollow shaft) or stirring speeds. The increase of stirring speed or hollow shaft stirrer choiceenhanced significatively gas/liquid transfer and thus strongly attenuated or even eliminated undercertain conditions the limiting factor at the vapor-liquid interface.