Comparison of Packed and Tray Columns

Wide range of liquid loads Wide range of gas loads 

Specialty alloys needed for corrosive fluids Available in cheap, noncorrosive materials 

Used mainly for distillation Used mainly for gas scrubbing or small-scale distillation ( 1 m diameter) 

The principal considerations that determine (or at least influence) the choice between packed and tray columns are the ability of either t) e to handle a given gas or liquid load, or range of loads, and the pressure drop per theoretical stage. Somewhat lower on the scale of priorities is the ability to handle corrosive fluids, liquids containing solid impurities or components with a potential to crystallize, and liquid hold-up. 

Packed columns score well in terms of low Ap, robustness over a wide range of gas loads, and ready availability of corrosion-resistant components. They are less suitable for handling a wide range of liquid loads (distillation) or fluids with a tendency to deposit solids. These are the preferred domain of tray columns. Table 8.2 summarizes the principal advantages and drawbacks of the two types. 

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