Thermodynamic Modeling of Gaseous Hydrates

Almost all recent activities on the prediction of hydrate crystal formation conditions are based on the science of thermodynamics. In the study of equilibrium in the formation of hydrates, we are faced with different phases, and therefore the best way is to use the specific model of that phase for each phase so that we can calculate the fugacity’s more accurately. The most common thermodynamic model used to predict the properties of a gas phase is the "state equation". In the hydrate system, two types of additives are used. When the hydrate phenomenon is known to be harmful, inhibitors are used to prevent the formation of hydrates. In addition, due to the unique properties of hydrates, improvers are used to improve the conditions for hydrate formation. Thermodynamic models in the presence of inhibitors are modified by calculating the coefficient of activity and solubility of the components. Because in the presence of additives, the activity coefficient will no longer be one and on the other hand in the presence of inhibitors the solubility of gaseous components in the aqueous phase changes. The paper examines the model and its results in the presence of inhibitors. The inhibitors considered in this work are ethylene glycol and methanol and the prediction of hydrate formation in the presence of this type of inhibitor with state equations such as SRK and PR has been investigated.