An improved method for calculating critical temperatures and critical pressures in natural gas mixtures with up to nC11 hydrocarbons

Abstract

This study suggests an improvement to the empirical model proposed by Peng (1986, Can. J. Chem. Eng. 64, 827–830) to calculate critical temperatures and critical pressures in natural gas mixtures. It aims to extend its application to natural gas mixtures containing hydrocarbons compounds up to undecane (nC11). This work focuses on establishing new matrices of coefficients Aij by obtaining new binary interactions between heavy compounds and the rest of compounds present in natural gas mixtures. The analysis considered more than 300 natural gas mixtures. Different comparisons were made between calculated critical properties, and referenced critical properties. Mean absolute errors <1.00% for the critical temperatures, and <2.70% for critical pressures were obtained. These low average deviations demonstrate the accuracy of this study, and could be considered as an easy-to-use engineering tool for estimating critical properties in natural gas mixtures, applicable to lean gas, rich gas, gas condensate, and Natural Gas Liquids (NGL).