AUSTHERM Pty Ltd - Hydrate Modelling

AUSTHERM Pty Ltd
A.B.N. 83 066 556 661
Solid Gas Hydrate Modelling

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Austherm Pty Ltd Principals have had a long interest in modelling the formation and decomposition of materials of industrial and environmental concern. One class of materials of particular interest are the solid gas hydrates.

Gas hydrates are important in the design and operation of super-critical fluid extraction processes, as a potential source of natural gas, in the processing of conventional natural gas and as a potential method of sequestering green- house gases.

Systems containing both carbon dioxide and water are of interest because of their aqueous phase chemistry as well as their gas-liquid-solid phase equilibria. The prediction of the acidity of co-existing aqueous solutions is of interest in corrosion control, in reactions with natural minerals and in considering the well-being of living organisms. Many solid carbonates and hydrogen carbonates have limited solubility in aqueous solutions so prediction of their possible formation is of importance.

We have compared the molecular and chemical thermodynamic approaches to modelling systems and processes involving gas hydrates. We have used the chemical thermodynamic approach to model the stability of carbon dioxide hydrate using experimental data from the published literature. This approach has been found to indicate a simple linear temperature-dependent stability of hydrates, the two parameters reproducing the expermental data with high precision. The predicted enthalpies of formation of solid hydrates compare well with those in the published literature and may be used to model the thermal changes in processes.

Austherm Pty Ltd has applied the chemical thermodynamic model to hydrate formation during gas processing, during super-critical fluid extraction, and to carbon dioxide hydrate chemical equilibria with sea water. We believe that our methods may be applied to most situations were prediction of gas hydrate formation is of importance. Our particular expertise is our ability to predict the overall chemistry of systems under conditions when hydrates form.

Austherm Pty Ltd uses the Gibbs energy minimisation approach to the calculation of chemical and phase equilibrium. This approach allows similtaneous calculation of aqueous phase chemistry and multi-phase equilibrium, including the use of solid-solution models for hydrate phases containing multiple vapour-phase species in the solid lattice.

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