LIQUID-LIQUID VAPOR-PHASE EQUILIBRIA IN THE SYSTEM METHANE PLUS ETHANE PLUS EICOSANE - RETROGRADE BEHAVIOR OF THE HEAVY LIQUID-PHASE

The fluid phase behaviour of the ternary system methane + ethane + eic osane was studied experimentally with special emphasis on liquid-liqui d-vapour equilibria and retrograde condensation of the second, heavier liquid phase in this region. P, T sections for mixtures of constant c omposition were determined according to the synthetic method for nine constant molar ratios of ethane and eicosane and different mole fracti ons of methane. The temperature range investigated was 290-307 K and t he pressure range 5.0-6.4 MPa. Addition of methane to a binary ethane + eicosane mixture expands the three-phase curve to a region and shift s it to lower temperatures. The influence of the concentration of eico sane and of methane on the phase behaviour in the three-phase region a nd on retrograde phenomena is discussed.