Forced circulation evaporators use pumps to circulate liquid through tubes at high pressure. This prevents boiling and elevates the boiling point. When the liquid exits the tubes, the sudden pressure drop causes flashing to vapor. This forced circulation and flashing leads to more efficient evaporation. Forced circulation evaporators are useful for evaporating viscous or heat-sensitive substances since the pumping action prevents localized overheating and the rapid flow reduces thermal damage. However, they require more energy due to the power needed to drive the pumps.

1. Forced Circulation
Evaporation

2. Name: Reg. No.
Smaranika Rahman
Zobaida Mostarin Nishi
15103092
15103094

3. Forced Circulation Evaporator:
Long tube type evaporator
where force is used to drive
the liquid through the
evaporator tubes thus
producing high tube
velocities.

4. 1. Horizontal
heating type:
2. Vertical
heating type:
Types:

5. Principle:
In forced circulation evaporator liquid
is circulated through the tubes at high
pressure by means of a pump. Hence
boiling does not takes places because
boiling point is elevated. Forced
circulation of the liquids also creates
some form of agitation. When the
liquid leaves the tubes and enters the
vapor head, pressure falls suddenly.
This lead to the flashing of super
heated liquor. Thus the evaporation is
effected.

6. 1. A centrifugal pump.
2. (1-2)/(1-1) shell &
tube heat exchanger.
3. An evaporator
body with vapor
outlet at the top.
4. Deflector plate.
5. An outlet for
product discharge at
the bottom.

7. 1.
• Steam→Calendria
• Pump →Positive
velocity
2.
• Mixture →deflector
• Cyclone Separator
→leaves vapour
3.
• Concentrated
Liquid → Pump
• Concentrated liquid
→ Collect
Working Procedure

8. Advantage:
• In forced circulation evaporator there is a rapid liquid
movement due to high heat transfer coefficient.
• Salting, scaling and fouling are not possible due to forced
circulation.
• This evaporators is suitable for themolabile substances
because of rapid evaporation.
• It is suitable for the viscous preparation because pumping
mechanism is used.
Disadvantage:
• The equipment is expensive because the power is required
for the circulating the liquids.
• The hold up of liquids is high.

9. Pharmaceutical Application:
• If evaporation is conducted
under reduced pressure,
forced circulation evaporator
is suitable for thermolabile
substances.
• This method is used for the
concentration of insulin and
liver extracts.
• It is well suited for
crystallizing operation where
crystals are to be suspended
at all times.

10. Reference:
• https://en.wikipedia.org/wiki/Circula
tion_evaporator
• C.v.s subrahmanyam et al.,
pharmaceutical engineering principles
and practices - evaporation, 2001,
page no. 351 - 352.
• https://www.indiamart.com/mazda-
limited-mumbaimumbai/evaporator-
system.html
• http://www.pharmainfo.net/book/ph
armaceutical-machines/forced-
circulation-evaporator