A new high-pressure vapour–liquid equilibrium apparatus

A new variable volume static type high-pressure VLE apparatus has been designed, constructed, and tested on a number of systems. The apparatus has an operating temperature range from 250 K to 393 K and pressure range from absolute vacuum up to 120 bar. The stainless steel equilibrium cell has sapphire viewing windows and a novel liquid sampling technique utilizing gas chromatographic sampling valves which permit phase sampling without disturbance to the equilibrium condition. The apparatus was tested by measuring VLE isotherms for some binary systems, viz., carbon dioxide + toluene at 283.25 K, 311.15 K, 353.15 K and 391.45 K; carbon dioxide + methanol at 263.15 K, 273.15 K, 313.15 K, 363.15 K and 373.15 K; and propane + 1-propanol at 323.15 K, 378.15 K and 393.15 K. Satisfactory modeling was obtained of the measured VLE data and thermodynamic consistency tests showed the data to be not inconsistent.