Natural gas often contains heavy hydrocarbons and/or other contaminants which need to be removed before the gas is liquefied. If these impurities are not removed, they can freeze-out at the cryogenic temperatures present in LNG plants and pose a risk to safe, reliable, and economic plant operation. To assess the risk of a freeze-out event occurring, it is vital to predict the conditions (temperature, pressure, and composition) under which solids can form. High accuracy is required for these predictions, as operating a plant 1-2 K away from its optimum conditions to avoid solid formation can significantly reduce its overall energy efficiency and increase operational costs.
Thermodynamic models for the freeze-out process require both pure component data (for the contaminant/impurity of interest) and phase equilibrium data for the relevant mixtures (including solid-fluid equilibria). The aim of this project is to conduct an experimental campaign to measure these data using a high-pressure, cryogenic, optical apparatus. The obtained data will be used to improve the predictions of thermodynamic models of the solubility of heavy hydrocarbons and other contaminants in methane. These models will be implemented in the freely available software package, ThermoFAST 2, to enable widespread use in the LNG industry. This will allow the operators of LNG plants to better assess the conditions under which freeze-out events can occur, meaning that these plants can be operated more safely and efficiently.
Partners: GPA Midstream, The University of Western Australia
Project Leader: Prof. Eric May
Duration: 36 Months