Azeotropic information are very important for the design of distillation processes.
Spinning band column
For the measurement of azeotropic data, a micro spinning band column with an electronically controlled reflux ratio is used. This equipment allows measurements up to pressure of 2.5 bar. The experimental setup is shown schematically in the following figure.
Depending on the liquid load and the number of revolutions of the spinning band (optimum speed 2000 rpm), up to 50 theoretical stages at a low pressure drop can be realized. Since the reflux works on the basis of a vapor dividing principle, not only homogeneous but also heterogeneous pressure maximum azeotropes can be determined. With the help of a vacuum pump for pressures below atmospheric and a nitrogen reservoir with a pressure of ~5 bar for higher pressures in connection with the manostat the desired pressure is kept constant. The temperature is determined with the help of a Pt100 resistance thermometer and the pressure by means of a sensor. For the analytical determination of the azeotropic composition, gas chromatography is used.
J. Gmehling, R. Bölts: Azeotropic Data for Binary and Ternary Systems at Moderate Pressures; J. Chem. Eng. Data (1996), 41, 202 - 209.