Carbon dioxide hydrate equilibrium conditions in aqueous solutions containing electrolytes and methanol using a new apparatus

A knowledge of the gas hydrate formation conditions, i.e., pressure, temperature, and compositions, of the coexisting phases at equilibrium, is required in formulating processes to avoid their formation in natural gas transmission lines or processing equipment. Additives like methanol and electrolytes are often used to inhibit hydrate formation in industrial ope:rations. Computation of the inhibition effects of these additives is necessary for the design. of such operations. Development of thermodynamic methods to calculate the hydrate equilibria conditions requires accurate experimental data. In the present work experimental three-phase (aqueous liquid solution, vapor, and incipient hydrate) equilibrium conditions of CO2 hydrate formation in aqueous solutions of electrolytes and methanol are measured in the temperature range of 263-279 K and pressure range of 0.9-3.0 MPa. A new ''full view'' sapphire tube equilibrium cell and the associated equipment are designed, fabricated, and used for the measurements. The equipment details and the measured data are also reported here.