An improved Parrish-Prausnitz (P-P) model to predict the hydrate formation condition of natural gas with a high volume content of CO₂

Predicting the hydrate formation condition is an important issue for determining high CO₂content natural gas transport. The widely used Parrish-Prausnitz (P-P) model cannot predict the hydrate formation temperatures and pressures accurately for high CO₂content natural gas. This paper introduced a simple correction factor into the P-P model, resulting in an improved P-P model. The analytical expression of this new parameter is developed by correlating the deviations of the predicted hydrate formation temperatures with the CO₂molar fraction in the gas mixtures. A total of 140 sets of experimental data were applied to validate the proposed model, which covered wide pressure and CO₂molar fraction ranges of 1.45–13.0 MPa and 0–90%, respectively. The results show that the improved P-P model balances a simple form with high accuracy. The average deviation of the improved P-P model is 0.098 °C, whereas that of the original P-P model is 2.424 °C. It is essentially comparable in its prediction ability to CSMGem software and the cell potential method when it is applied to predicting the hydrate temperatures of high CO₂content natural gases.