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.
Three flow rates, three different meanings
Feed throughput is the liquid entering the equipment. Concentrate flow is the product leaving it. Evaporation capacity is the water removed. A nameplate or quotation using only “kg/h capacity” leaves an important ambiguity. Ask which stream the figure describes and whether it is a normal duty, maximum duty or test result.
Start with a conserved-solids balance
For a steady-state balance with no solids addition, loss or accumulation, concentrate flow equals feed flow multiplied by inlet solids fraction and divided by outlet solids fraction. The difference between feed and concentrate is evaporated water. At 1,000 kg/h feed, 12% inlet solids and 60% outlet solids, this example gives 200 kg/h concentrate and 800 kg/h water removal. These are calculated mass flows, not a machine rating.
State the operating case
Give feed temperature, product composition, final concentration, available production hours and anticipated load variation. Brix can provide an approximate basis for some food liquids, but it is not automatically equivalent to total non-volatile solids. Heating area and utilities still require a heat balance and product-property information.
Make offers comparable
Ask every proposal to identify the same inlet and outlet conditions, operating range, utility quantities and acceptance method. Confirm whether preheating, vacuum, condensate removal, concentrate pumping and cleaning are included. Keep rated duty and the installed scope together when comparing prices.
Related selection resources
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.
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.