Consider the conventional schematic diagram of a plate distillation column with a total condenser and a partial reboiler shown in Figure 5-1. Assume constant molal overflow (CMO), constant pressure, and no heat leak. With the constant pressure and zero heat leak assumptions, a degree-of-freedom analysis around the column yields C + 6 degrees of freedom, where C is the number of components. For binary distillation this is 8 degrees of freedom. In a design problem we would usually specify these variables as follows (see Tables 3-1 and 3-2): F, z, feed quality q, distillate composition x_{D}, distillate temperature (saturated liquid), bottoms composition x_{B}, external reflux ratio L_{0}/D, and the optimum feed stage. With ...

Start Free Trial

No credit card required