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The difference in cost between plate and packed columns is not too great, although packings are generally more expensive than plates.

In addition, the difference in column height is not usually significant if the flow rates are such that efficiencies are near maximum.

Conditions favouring packed columns:

Small-diameter columns (less than 0.6m)

More choices in materials of construction for packings especially in corrosive service (e.g. plastic, ceramic, metal alloys)

Lower pressure drop (important in vacuum distillation)

Less liquid entrainment · low liquid hold-up, especially suitable for thermally sensitive material

Foaming liquids can be handled more readily (less agitation of liquid by the vapour)

Conditions favoring plate columns:

Variable liquid and/or vapour loads

Low liquid rates · large number of stages and/or diameter

High liquid residence time

Dirty service (plate columns are easier to clean)

Presence of thermal or mechanical stress due to large temperature changes which might lead to cracked packings

Exotherms requiring cooling coils inside column

As a rule of thumb, plates are always used in columns of large diameters and towers that have more than 20 to 30 stages.



Attributes

Packed Tower

Tray Tower

Gas Pr Drop

Smaller

Liquid hold up

Smaller

Liquid / gas ratio

High values can be best handled

Low values can be best handled

Liquid cooling

Cooling coils more readily built

Side Stream

More readily removed

Foaming system

Operate with less bubbling of gas & hence more suitable.

Corrosion

For difficult corrosion, less costly

Solid present

Not satisfactory

Not satisfactory

Cleaning

Frequent, Cleaning difficult

Easier

Temp. Fluctuation

Fragile packing tend to crush


Thanks for reading - Packed Columns vs. Plate Columns
Naitik Patel
Industrial Guide

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