Thermophysical Properties, Hydrate and Phase Behaviour Modelling in Acid Gas-Rich Systems

International audienceIn this communication we present experimental techniques, equipment and thermodynamic modelling for investigating systems with high acid gas concentrations and discuss experimental results on the phase behaviour and thermo-physical properties of acid gas-rich systems. The effect of high CO 2 concentration on density and viscosity were experimentally and theoretically investigated over a wide range of temperature and pressures. A corresponding-state model was developed to predict the viscosity of the stream and a volume corrected equation of state approach was used to calculate densities. The phase envelope and the hydrate stability (in water saturated and under-saturated conditions to assess dehydration requirements) of some acid gas-rich fluids were also experimentally determined to test a generalized model, which was developed to predict the phase behaviour, hydrate dissociation pressures and the dehydration requirements of acid gas rich gases

Direct measurement of hydrate equilibrium temperature in CO₂ and CO₂ rich fluids with low water content

A high-pressure experimental setup was used to obtain experimental data on the hydrate equilibrium (melting) temperature (HET) of hydrates formed from low water content CO2 and CO2 rich mixtures. A novel method was used to measure hydrate formation temperature in addition to melting temperature directly at realistic temperature/pressure conditions encountered in transport by pipelines or ship. The method can be used to evaluate the likelihood of hydrate formation in pipelines/ships transporting pure CO2 and CO2 coming from capture processes as well as from high CO2 content produced gas. The data generated from the measurement can also be used to investigate the kinetics of hydrate formation and dissociation in low water content fluids at pipeline/ship conditions. This paper details the experimental equipment, methods, test fluids and results. Experimental results are compared against predictions of the simplified cubic plus association equation of state (sCPA-EoS) coupled with the van der Waals and Platteeuw solid solution theory