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Multiple-effect evaporators and concentrators

The ANDRITZ RecoVap multiple-effect evaporator utilizes proven lamella-type heating surfaces for high efficiency and reliability.

The challenge

To process the spent cooking liquors or effluent using the minimum amount of energy while maximizing product dry solids, plant availability, and condensate quality.

The solution

The ANDRITZ RecoVap evaporator uses proven lamella-type heating surfaces. Inherently non-scaling, this allows the use of various heat sources and enables selection of the most energy-efficient process connection.

Pioneers in high dry solids evaporation

RecoVap evaporators use crystallization technology to produce the highest dry solids with minimum washing requirements. As an option, systems for liquor heat treatment (to reduce liquor viscosity) and calcium de-activation (to prevent calcium scaling) can be integrated directly into the RecoVap evaporator.

Fully integrated stripper

The stripper is part of the multiple-effect evaporator system. Typically, the heat source for the stripper is from effect #1 and the stripper vapors are condensed in effect #2 to maximize energy efficiency.

Inherently non-foaming design

The evaporation process inside the RecoVap relies on free flow falling film techniques. This produces low vapor velocities and low shear rates inside the evaporator, which eliminates foam generation in difficult applications.

Non-plugging design

Uniform liquor distribution on the heating elements and continuous redistribution of the liquor by the dimpled shape of the surface ensures a completely wetted heating surface and eliminates local scaling or over-concentration of liquor. The lamella-type heating surface ensures that water-soluble scaling can be washed away by a simple dilution wash, eliminating the need for time-consuming and costly outages for cleaning.

Optimized liquor distribution

The design of the RecoVap takes full advantage of the lamella-type heating surface to optimize liquor distribution system and internal circulation flows. This results in excellent liquor distribution over the entire effective heating surface with minimum pumping power – saving capital and energy costs.

Cleanest condensates

Highly efficient condensate segregation in the evaporator ducts and lamellas, plus the integrated stripping of foul condensate fractions, produces clean and re-usable water. The methanol is separated from the condensate and recovered in an ANDRITZ methanol liquefaction system.

Efficient chloride and potassium removal

Crystallization technology is used in the integrated system for removal of chlorides and potassium. Energy consumption is minimized by using the secondary vapor from the evaporator for the crystallization process. ANDRITZ recovery boilers utilize an ash leaching process for simpler and cheaper removal of chlorides and for potassium removal.

Best possible energy efficiency

The use of fully integrated foul condensate stripping, optimized liquor distribution, the ability to use various heat sources within a single thermal effect, and many years of experience with mechanical vapor recompression (MVR) evaporation create an evaporation system that meets unique customer requirements while providing the best possible availability and energy efficiency.


  • Energy-efficient evaporators for optimum mill operation
  • Highest firing liquor dry solids with maximum availability using crystallization technology
  • Cleanest reusable condensates at optimum temperatures using the minimum amount of steam
  • Lowest steam and electricity consumption
Evaporation plant lamella

Evaporation plant lamellar

Evaporation plant

Evaporation plant


ANDRITZ Oy, Finland

Phone: +358 (0)20 450 5555

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