Wiper System

Continuous agitation of the product film on the evaporator surface can significantly improve process performance due to:

• uniform distribution of the material on the evaporator surface
• mixing and enlarging the surface of the product film
• improved heat transfer into the film
• avoidance of fouling

This is accomplished with a wiper basket consisting of a rotating distribution plate and several wiper strands. A wiper strand consists of a guiding rod equipped with a series of wiper elements.

Wiper baskets from UIC are mounted without a footstep bearing, i.e., they are free-hanging above and outside the vacuum chamber. A simple or double acting mechanical sealing is isolating the wiper basket shaft from the vacuum chamber.

For materials with sufficiently low viscosity (η ≤ 1.000 mPa·s) roller wipers have proven most effective. Their functional principle can be easily captured from the pictures.

As the internal diameter of the rollers is larger than the external diameter of the guiding rod, the rollers can penetrate the film and adapt themselves to different film thicknesses. There is no mechanical contact between roller wipers and evaporator surface which largely prevents abrasion and scratches.

Splashing that may occur from the roller wipers due to centrifugal forces can be remedied with splash guards.

Advantages of a roller wiper system include:

• Self cleaning
• Self lubrication
• Optimal agitation of the product film
• Virtually no fouling at the roller wipers
• Virtually no abrasion

Roller wiper systems are UIC's preferred choice and have been implemented in the majority of plants delivered so far by us.

For feed materials with higher viscosities or sizeable solid content block wipers may become a viable alternative.

Picture Gallery