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

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

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Process Equipment and Plant Design
A forced circulation long tube vertical evaporator as compared to the natural circulation evaporator

Employs a centrifugal pump placed between external downtake from vapor drum and inlet to tube bundle
Both B & C
Employs high velocity, high heat transfer rate and less heating surface requirement
Is economical in operation

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