In industrial applications and during natural gas transport, the presence of water under liquid form or within a vapour phase can lead to gas hydrate formation causing the blockage of industrial units and transport lines. Hence, in order to avoid such situation, it is very important to well determine its formation conditions. It is occurred by using a rigorous thermodynamic model. Due to the lack of data in the literature concerning gas hydrates formation in the absence of an aqueous phase,usual thermodynamic models predict correctly gas hydrate dissociation temperature only in the presence of aqueous water. Our purpose is to propose a thermodynamic model with hydrate phase that can predict gas hydrate dissociation temperature in both cases: with and without water liquid phase.At first, using an existing apparatus, we have developed a new experimental protocol in order tomeasure gas hydrate dissociation temperature in the absence of liquid water. It consists in measuring the water content in the vapour phase as a function of the temperature by using a Karl Fischer coulometer. We have measured the dissociation temperature of many simple and mixture hydrates.We have also developed a thermodynamic model that is able to predict correctly gas hydrate dissociation temperature, in the absence and in the presence of liquid water. This model is based onthe use of Dharmawardhana's approach for the calculation of hydrate fugacity in the empty hypothetical hydrate, Kihara potential for the calculation of the Langmuir constant and CPA EoS forfluid phases modelling. We have shown that the use of CPA EoS improves the prediction of gas hydrate dissociation temperature. We have also developed a biphasic flash (hydrate-fluid) allowing the calculation of the formed mixture hydrate amounts. The calculated amounts are in agreement with the experimental ones.
