Forced circulation

Force is used to driving the liquid through the evaporator tubes thus producing high tube velocities. A high efficiency circulating pump, designed for large volume and sufficient head, is used to supply the force. Forced circulation evaporator is suitable in the pharmaceutical area for evaporation of thermolabile substance.

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. 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/Circulation_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/pharmaceutical-machines/forced-circulation-evaporator