Development and testing of a new apparatus for the measurement of high-pressure low-temperature phase equilibria

A new apparatus for the study of high-pressure phase equilibria at low temperatures using an analytical method was designed, assembled and tested. The apparatus was specially developed for the study of multi-phase equilibria in systems containing hydrocarbons, water and hydrate inhibitors, at temperatures ranging from 213 K to 353 K and pressures up to 40 MPa. The core of the apparatus is a variable-volume equilibrium cell, equipped with a 360° sapphire window and connected to an analytical system by three capillary samplers.The quality of the apparatus was confirmed through several tests, including the study of the system methane + water. An equilibrium point for the quaternary system methane + n-hexane + methanol + water is also presented.

► A new apparatus for the study of high-pressure phase equilibria at low temperatures using an analytical method is described. ► The experimental set-up was tested, namely through the study of the binary system methane + water. ► A test was made with the quaternary system methane + hexane + methanol + water. ► The comparison of the obtained results with literature values confirms the quality of the new apparatus.