Forced circulation evaporators
are most suited for the liquids which tend
to crystallize upon concentration and which
have tendency to scale.
Evaporators in which circulation
is maintained, regardless of evaporation
rate or heat duty, by pumping the liquid
through the heating element with relatively
low evaporation per pass are suitable for
a wide variety of applications.
The forced circulation
system is the easiest to analyze and permits
the functions of heat transfer, vapor-liquid
separation, and crystallization to be separated.
Forced circulation systems are generally
more expensive than natural circulation
systems and are therefore used only when