Process Equipment and Plant Design
Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column.

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
Maintenance cost for valve and seive trays are comparatively more than bubble cap tray due to their relatively complicated construction features
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

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Process Equipment and Plant Design
In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement

Creates relatively lower turbulence on the shell side resulting in lower shell side heat transfer co-efficient
Can accomodate less number of tubes for a given shell diameter
Results in higher shell side pressure drop
Facilitates easier shell side cleaning; hence is more suitable for handling high dirt factor shell side fluid

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Process Equipment and Plant Design
Pick out the wrong statement pertaining to the design of a horizontal tube evaporator.

It is suitable for process, in which the final product is a liquor instead of solid
Its usual dimensions are: tube dia = 2-3 cms; evaporator body dia = 1-4 metres and evaporator height = 2.5-4 metres
Liquor flows inside the tube, while the steam is outside submerging the tube
It is unsuitable for concentrating those liquids, which form a scale or deposit salt

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Process Equipment and Plant Design
The centre to centre distance between two consecutive baffles in a shell and tube heat exchanger is called the baffle pitch or baffle spacing, which is more than 1/5th the I.D. of the shell. Which of the following is not a function of the baffles?

To increase the tube side heat transfer co-efficient by inducing turbulence
To reduce the induced vibration in the tubes
To provide support to the tube bundle
To increase the residence time of shell side fluid

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