Experimental Methods to Study Hydrate Phase Equilibria

1 Experimental Methods to Study Hydrate Phase Equilibria 

Knowledge of CO2 hydrate formation conditions is very important for rational and design of processes in CO2 capture and sequestration. Several studies have focused on determination of incipient CO2 hydrate formation conditions. The condition at which an infinitesimal amount of hydrate phase is present in equilibrium with liquid phases is referred to as incipient hydrate formation condition [28]. Using different experimental methods, macroscopic hydrate phase equilibrium can be determined 

All these methods were used to determine phase equilibrium above the ice point, i.e., Lvr-H-V line. 

This method operates at isobaric condition (constant pressure). The crystallizer with a gas-liquid system is set to pressures at which the hydrate equilibrium temperature needs to be determined. Initially the pressure of the system drops because of dissolution of the gas into the liquid caused by mixing. The pressure of the system is maintained constant by a supply of gas from the reservoir or fluid withdrawal. The system temperature is decreased to induce hydrate formation. The pressure of the system drops because of cooling and hydrate formation. After hydrate formation, the temperature of the system is increased slowly until an infinitesimal amount of hydrate crystals exists in equilibrium with the vapor and liquid phases. During heating, the system pressure is maintained constant by fluid withdrawal. This point is recorded as equilibrium condition. The equUibiium point is determined by visual observation. 

---