The stirrer rotation effects of gas hydrate performance in the hydrate crystallizer

Abstract

Gas hydrate is a crystalline solid consist ice in the shape of water and gas on a high pressure and low temperatures conditions. The water molecules have hydrogen bonds form a framework which has a cavity. Inside the cavity among the water molecules, there are gas molecules trapped in a variety of shapes and sizes. Some researchers have been investigated about it, mainly the application of the research was embodied in the storage of gas hydrate. It is because the hydrates are already considered an important thing in storage media of industrial petroleum. Then, the performances of gas hydrates include the formation rate, the hydrate stability, and the storage capacity. In this study, it was used propane-butane as gas for clathrate. The research aims to know the influence the hydrate performance by influencing the rotation of stirrer inside the crystallizer that predicted to increase the agitation of the hydrate performance. In the research, the stirrer rotation speeds were rotated at 200 rpm, 300 rpm, and 400 rpm. Then, it were investigated the performances. The water inserted in the crystallizer has 50 ml in volume using the demineralized water. The temperatures used were 273 K at the hydrate formation and 268 K at the hydrate stability measurements. As for the pressure, it was used 0.2 MPa. The results showed that the stirrer rotation speed of 400 rpm has the highest hydrate formation rate, stability, and storage capacity compared to the other rotation speed. It is due to the fast rotation of stirrer resulted in the existence of centrifugal force which led to agitation (cavitation or turbulence) in the larger system. Therefore, the mass transfer of gas into the cavity of water molecules and the heat transfer from the cooling bath to the system more quickly. It causes the fast hydrate formation. Then, the fast one made the penetrated gas inside the water molecules stronger making the high stability of hydrate. If the hydrate had the high stability, it would be also high the storage capacity in the room temperature. Meanwhile, the 200 rpm has the lowest one.