The vapor rising in the column gets richer and richer in light components at each stage. This illustrates precisely why a distillation column can be used to separate chemical components. O-Xylene, on the other hand, the heaviest component, has a higher concentration in the liquid than in the vapor. Benzene, the lightest component, has a higher concentration in the vapor than in the liquid. Notice the enriching of lighter component that occurs in the vapor in the above example. When convergence has been achieved, calculate vapor compositions. If Pctc is greater than PT, decrease T.Ħ. Check to see if Pctc is sufficientiy close to PT.ĥ. Calculate vapor pressures of all components at T.Ĥ. The calculation procedure is iterative:Ģ. This is by far the most common type of calculation encountered in distillation work because column pressure is usually known.
The problem is to calculate the unknown temperature or pressure and the composition of the vapor phase (j>y).īubble-Point Temperature Calculation. In addition we must be given either the pressure or the temperature of the system. In all bubble-point calculations, we know the composition of the liquid (x/s are all given).
