A new kinetic model for gas hydrates using collision theory.

摘要

This thesis involves the modeling of a new kinetic rate equation for gas hydrate system blending the knowledge of statistical thermodynamics and chemical kinetics. The approach is a basic molecular level dynamic simulation using a software package called Moldy and collision theory for chemical kinetics. The fugacity is obtained using Peng Robinson equation of state which is used to calculate the concentration of methane. By using the crystallographic data to define the positions of methane molecules in the water lattice, ensemble averages of molecular level energies are calculated using Moldy. Energy and the collision numbers obtained are used as parameters to obtain the rate constant which is the most important parameter in the rate expression for formation of hydrates. A novel rate expression is modeled using the above mentioned parameter which is then compared with the experimental values. The model reveals that the formation rate is a strong function of difference in the collision number at system pressure and the three-phase equilibrium pressure at a given temperature. The rate constant indicates weak temperature dependence.