Multi-component liquid-steam operations
Material transfer - Ideal compartmentalized distillation

Clearly, a rectification column can only separate a mixture of n components into two groups, one of k components, the other of (n - k) components (0 < k < n): (n - 1) columns are therefore needed to achieve total separation. For a given column, you need to specify the separation you wish to achieve. To do this, it is useful to define the key constituents of the mixture to be separated:

• the light key is mostly collected at the condenser, along with all its more volatile constituents;

• most of the heavy key is collected at the boiler, along with all its less volatile constituents.