Question

The packed towers are preferred over plate columns in distillation, because of

• A. Low pressure drop and low hold up
• B. Low pressure drop and high hold up
• C. High pressure drop and high hold up
• D. High pressure drop and low hold up

Hint:

Packed towers are preferred when low pressure drop and low liquid hold up are required.

Answer 1

The Correct Option is A

Packed towers contain packing materials instead of trays or plates. Vapour and liquid flow through the void spaces in the packing. Packed towers generally offer lower resistance to vapour flow. Therefore, pressure drop in a packed tower is lower than in a plate column. Packed towers also have lower liquid hold up. Low hold up is useful for heat-sensitive materials because residence time is reduced. Plate columns have trays, downcomers, and liquid pools, so hold up and pressure drop are generally higher. Therefore, packed towers are preferred over plate columns because of: \[ \text{low pressure drop and low hold up} \]