Wiped Film Evaporators
Pfaudler has been manufacturing Wiped Film Evaporators since 1950's. These evaporators have found a niche in difficult evaporation operations. Though this style evaporator can be used in almost any application, the WFE excels in distillation steps where products are heat sensitive, viscous, tend to foul heated surfaces, or are high temperature boiling.
Pfaudler Wiped Film Evaporators are operating in plants world wide. Wiped Film Evaporators can be installed in a variety of configurations. WFEs with internal condensers are called short path evaporators and can operate under high vacuum. Wiped Film Evaporators without internal condensers are called top vapor outlet (TVO) and employed as column reboilers or in very dirty applications.
Major Benefits of a Wiped Film Evaporator
- Short residence time (liquid is on the hot surface for seconds)
- Operate Under High Vacuum (reduced operating temperature)
- Excellent Heat Transfer (process film is continuously agitated)
- Handle Viscous Fluids (wipers pump liquid down & provide thin film)
- Handle Dirty/Fouling Fluids (wipers continuously agitate film)
- >90% Distillate in Single Pass (without recirculating)
- No Bottom Steady Bearing (wipers effective at low speed)
How does a Wiped Film Evaporator work?
- Feed enters at top
- Falls to rotating distributor plate
- Evenly distributed to heat transfer wall
- Wiper blades create thin film
- Slots in blades dissipate bow wave and pump fluid down
- Heat is transferred from jacket
- Vapors are generated and flow radially inward
- Vapors pass through rotated entrainment separator
- Liquid droplets impinge on the entrainment separator and are returned to heated wall
- Vapors condense on internal condenser
- Distillate flows down tubes and out distillate outlet
- Bottoms product continues down wall and exits bottoms outlet
- Non-condensed vapors exit the vacuum outlet
Wiped Film Evaporator Styles
- WFE Sizes: from 1.2 to 600 ft2 std, (0.1 to 56 m2)
- WFE Wetted Materials of Construction: 316LSS std, any alloy or glass lined steel
- Short Path Type Wiped Film Evaporator
- The Short Path Wiped Film Evaporator has an internal condenser. This allows for high vacuum operation by providing a short distance between the heated surface and the condensing surface. High volumetric vapor flow rates with negligible pressure drop are possible.
Major benefits include:
- High Vacuum Operation
- Compact Design
- Lower Installed Cost
- Better Stripping of Volatiles than TVO
, 39 m2
Short Path Wiped Film Evaporator shown in the Pfaudler test stand utilized in an application involving derivatives of plant sterols
- Top Vapor Outlet Type Wiped Film Evaporator
- The Top Vapor Outlet Wiped Film Evaporator requires an external condenser. The style can also be used as a reboiler for a distillation column.
Pfaudler Wiped Film Evaporators are engineered and built per A.S.M.E. code Section VIII Div. 1. European Pressure Vessel Directive (PED) and the Chinese Safety Quality License are also available upon request.
Major benefits include:
- Reboiler for Column
- Condenser Cleaning
- Better separation than short path
, 8 m2
TVO Wiped Film Evaporator for a petrochemical application