Process Equipment and Plant Design
A high vapour velocity is required for high plate efficiency in a seive plate coloumn. The satisfactory value of operating vapor velocity for design purpose in seive plate column is about __________ percent of the flooding velocity.
Bubble cap trays though most expensive are the best in situations, where low vapour rates is to be handled and a positive liquid seal is essential at all flow rates
Murphree efficiency of all the three trays are nearly equal, however the peak efficiency is generally higher for seive and valve trays than the bubble cap
Valve trays have the highest turn down ratio (i.e. the ratio of the highest to the lowest vapour flow rates) and thus provides the maximum flexible operating range
Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features
Plate tower is perferred, if interstage cooling is required to remove heats of reaction or solution
Plate tower is preferred over packed tower, if the operation involves liquids containing dispersed solids
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
The total weight of a dry plate tower is usually much more than that of a dry packed tower designed for the same duty
EXAMIANS