A Rising Film Evaporator (RFE) is combination of vertical shell & tube heat exchanger and vapor- liquid separator mounted on top.
The feed is given at bottom of shell & tube type heat exchanger and rises in tubes. Heat is given on the shell side by heating medium. As feed receives heat, vapor generated pushes the liquid on the wall as a film and lifts the liquid upwards. The mixture of liquid & vapor are separated at top in vapor- liquid separator.
Good thermal performance is achieved because of high velocity generated by vapor lift.
This upward movement against the gravity has the direct effect of creating a high degree turbulence in the liquid. This is one of its biggest advantage for viscous products which have a tendency to foul against the heating surfaces.
Features
- Circulation pump is not needed because of thermosiphon action in tubes due to boiling.
- Multiple effect arrangement can be provided to reduce steam consumption.
- Can handle small quantities of suspended particles.
- Effective for concentration of liquids which are moderately heat sensitive.
Applications
- Concentration of dilute solutions of plant extract in water or organic solvent.
- Re-boiler to distillation Column
- Used as a pre -concentration before final drying up to saturation point
For recovery of solvent from product or waste stream.