Viscosity and minimum wetting in falling film evaporation
Review concentrate viscosity, particles, distributor geometry and minimum liquid flow before choosing a falling film evaporator for a food liquid.
Check the concentrate, not just the feed
A liquid that flows easily at the inlet can behave very differently at its target concentration. Request viscosity measured at a stated temperature, concentration and method. Non-Newtonian behaviour may require more than one value. The final pass is often the condition that needs the closest review.
Wetting is a local requirement
A measured total flow does not show whether every active tube receives enough liquid. Distributor design, tube geometry, pass arrangement and recirculation influence the film. Uneven distribution and low flow can leave dry areas and encourage deposits. The minimum stable operating load must be part of the proposal.
Particles and foam change distribution
Describe filtration, suspended particles, fibres, foaming and feed flashing. A filter opening alone does not describe every particle or fibre shape. A representative product test may be needed where the distribution risk is uncertain. Do not assume every product sold as juice is suitable for the same tube and distributor arrangement.
Know when to consider another approach
When wetting cannot be maintained, deposits dominate, or the final product is too viscous for the proposed film, review the concentration target, routing and alternative evaporator principles. A forced-circulation or agitated-film comparison may be appropriate; suitability must be established from the product, not from a universal rule.
Related selection resources
How to specify falling film evaporator capacity
Separate feed throughput from evaporation capacity. Specify kg/h water removal, inlet and final solids, operating hours and the measurement basis.
Read the engineering basis ↗APPLICATION & SELECTIONEvaporator materials and CIP specification for food liquids
Specify product-contact materials, cleaning chemistry, inspection access, seals and CIP verification for a falling film evaporation project.
Read the engineering basis ↗APPLICATION & SELECTIONSteam, electricity and cooling-water checklist for evaporators
Prepare the utility data needed for steam, TVR or MVR falling film evaporation: pressures, electrical capacity, cooling conditions and operating hours.
Read the engineering basis ↗Give the equipment a clear brief.
Tell us the liquid, feed rate and concentration target. Add the utility conditions you know; we will identify what needs further review.