Determination of clathrate hydrates dissociation conditions in aqueous solutions of methanol and salt using the e-NRTL based model

Saline water and organic inhibitors have considerable effects on preventing the formation of clathrate hydrates in gas and oil industries. The purpose of this study was to demonstrate a model that is capable of estimating the effects of NaCl, KCl, CaCl 2 and methanol aqueous solutions on the equilibrium disso- ciation conditions of pure and gas mixture hydrates in wide ranges of pressure and temperature. The e-NRTL activity coefficient model is employed to describe the non-ideally of the liquid/aqueous phase. The solid solution theory of van der Waals and Platteeuw is applied to characterize the hydrate phase. The gas phase is described by the Peng-Robinson (PR) equation of state. No adjusting or fitting param- eter is used. A comprehensive evaluation of the estimated values and literature data reveals the great accuracy of this model. To give a definite opinion, the obtained results of the proposed model were com- pared to experimental data and the results of four other thermodynamic models where the e-NRTL based model exhibits the least average absolute deviation ( AAD ). The average AAD of the e-NRTL based model results over 828 experimental data points was determined to be 0.59 K, which demonstrates an excellent agreement between the experimental data and the predicted/estimated values.