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 CO2 content natural gas transport. The widely used Parrish-Prausnitz (P-P) model cannot predict the hydrate formation temperatures and pressures accurately for high CO2 content 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 CO2 molar 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 CO2 molar 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 degrees C, whereas that of the original P-P model is 2.424 degrees 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 CO2 content natural gases. (C) 2016 Elsevier B.V. All rights reserved.