Prediction of hydrate formation conditions in the solutions containing electrolyte and alcohol inhibitors and their mixtures using UNIQUAC-NRF models

•Hydrate equilibrium pressure calculations are carried out for single and binary gas mixtures in the presence of inhibitors.•The UNIQUAC-NRF and Electrolyte-UNIQUAC-NRF models are used to predict the hydrate pressure formation conditions.•The predicted values of hydrate pressure were compared with the experimental data.•The hydrate systems of several gases in the presence of methanol, binary and ternary electrolyte systems were investigated.

In this work, the prediction of hydrate formation conditions in the presence of the thermodynamic inhibitors is presented. Using the van der Waals–Platteeuw model, computation of the L–S–G equilibrium is carried out for hydrate formation conditions in the presence of methanol and electrolytes using the local composition models of the UNIQUAC-NRF and Electrolyte-UNIQUAC-NRF for nonelectrolyte and electrolyte systems, respectively. The model is applied to calculate water activity coefficient for prediction of the hydrate formation pressure of methane, ethane, H2S in the absence and presence of the electrolytes. The results of the present model are compared with the experiment and UNIFAC group contribution model. Also both UNIQUAC-NRF and UNIFAC activity coefficient models are used to predict the hydrate formation conditions in the presence of alcohols. The results show very good agreement with the experiment.