2602 Study on the characteristics of CO_2 hydrate formation

The objective of the present study is to elucidate the conditions which influence on CO_2 hydrate nucleation. In this study, we measured the induction time which is the time from putting liquid CO_2 droplet into the pressure chamber to forming the hydrate film to clarify the effect of the surrounding water conditions. Two types conditons of ion-exchanged water were filled in a pressure chamber under the pressure and temperature conditions of 40 MPa and 3〜5℃, respectively. In the case of using the water that had previously frozen as ice and melted at atmospheric pressure, hydrate formation was not observed. On the other hand, in the case of using the water that had previously frozen as ice and melted at hydrate formation pressure of 40 MPa, hydrate formation was identified. In addition the ratio of melted water weight was changed from 0 to 5 %. The lager the ratio of melted water induced the shorter the induction time. The relation between induction time and surrounding water conditions and mechanism of it are discussed.