Process Equipment and Plant Design
Pick out the wrong statement pertaining to the comparative evaluation of performance of the packed tower and the plate tower.
In operations involving large temperature changes. (e.g. distillation), plate towers are preferred over packed towers as the packing may be crushed due to large temperature changes
Plate tower is perferred, if interstage cooling is required to remove heats of reaction or solution
The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty
Plate tower is preferred over packed tower, if the operation involves liquids containing dispersed solids
Width of the calming section provided at the inlet and outlet sides of the plate is 75 mm for column diameter below 1.5 metres and 100 mm for larger diameter columns
For segmental downcomers, the chord length is 60-80% of the column diameter. An initial value of downcomer area of 12% is taken in the design
Minimum recommended downcomer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds
An increased weir height improves the tray efficiency at the cost of high plate pressure drop; optimum wear height being 40-90 mm for column pressure above atmospheric and 6-12 mm for vacuum columns
EXAMIANS