Vapour Liquid Equilibrium Measurements & Solid Formation Tests in Industrial Mix (23.RP1.0167)

The Challenge

Mixed refrigerant cycles are key to the efficient production of LNG. This project’s aim is to enhance the understanding of phase behaviour of a mixed refrigerant and to determine the optimum reliable predictive model of its thermodynamic properties.

Vapour liquid equilibrium (VLE) and solid formation predictions provided by different thermodynamic models can vary by significant amounts at low-temperature conditions, increasing the margins required when sizing process equipment.

Understanding the optimum reliable predictive thermodynamic model will avoid operational problems such as solid formation in the mixed refrigerant, and the need for over‐sizing of process equipment. Oversized equipment will significantly increase capital expenditure and undersized equipment will reduce operational output.


The solution and outcome

This project used an experimental visual technique with two-phase sampling developed by The University of Western Australia (UWA) to characterise VLE and solid formation behaviour of the mixed refrigerant down to its minimum operating temperature.

These results were compared to different thermodynamic models implemented in multiple software packages to determine the model with closest predictions to the physical measurements. Through this project systematic VLE measurements of phase component fractions and vapour volume were taken in order to recommend a reliable predictive thermodynamic model.

The research outcome provides the industry with know‐how regarding the optimisation of the mixed refrigerant composition and the associated liquefaction process. The optimum predictive thermodynamic model was determined and implemented in the process simulation software. This commercial in confidence knowledge will remain undisclosed in the public domain.


The impact for the future

The design of the mixed refrigerant composition and the associated liquefaction cycle requires a reliable model of its thermodynamic properties. The optimum predictive thermodynamic model will support the productivity, efficiency and safety of LNG process plants which hinge on proper equipment functionality.

Project Researchers

  • Prof Eric May
  • Dr Brendan Graham
  • Dr Peter Metaxas
  • Dr Peter Falloon

Project Status