Distillation Columns

General Description

  • Essentially a tall vertical cylindrical shell with a number of nozzles
  • The internals of the column consist of a series of plates or trays or a variety of packings
  • Distillation column and absorption column are most widely used in the chemical industry
  • Divided into two types, namely plate or tray columns and packed columns

Plate/tray columns
The perforated plate holds the liquid and gas is sparged through this pool of liquid. The various devices in practice are bubble cap tray, valve tray, sieve plate etc. Thus on the device liquid used the continuous and gas is dispersed phase.

Packed Columns
These columns are filled with proprietary packings such as raschig rings, pall rings, intalox saddles, cascade mini rings, sulzer mella pack etc. These packings provide intimate contact between gas/vapour and liquid. Here the gas phase is deemed as continuous while liquid as dispersed.
The height of the column is mainly governed by mass transfer considerations.
Total height of a column is sum of space required for mass transfer device and tower internals such as packing support plate, hold down plate, liquid distributor, gas/vapour distributor, liquid redistributor and demister etc.