Investigating Thermodynamic Mechanism of Gas Hydrate Formation in Natural Gas Transmission Pipelines

Natural gas hydrate is a solid crystalline compound formed by combining water and belongs to Klatryts’s family. Guest gas molecules are trapped in water lattice cavities created by hydrogen bonds between water molecules. Based on Long and Quam’s model, hydrate formation at low temperatures and high pressures can be explained. As temperature decreases, the kinetic energy of the molecules of liquid phase decrease and the number of hydrogen bonds between water molecules increases. The formation of these bonds increases the number of molecular aggregations on the surface. As the number of cavities increase, the conditions for hydrate formation become more favorable and the chance of gas molecules being suddenly trapped in one of these cavities increases. Similarly, as the pressure increases, the number of gas molecules per unit of water surface increases, the probability of gas molecules being trapped in one of these cavities increases, which in turn increases the risk of hydrate formation. Based on tests of Leatherhaus et.al, it can be concluded that inhibitors such as salt can slow or stop the process of hydrate formation by reducing the number of cavities on the surface or like PVcap by blocking the cavities.

Keywords:

Hydrate , Liquid Phase , Hydrogen Bond , Inhibitor