As energy costs increase, the use of Mechanical Vapor Recompression (MVR) evaporators has also increased. The energy savings possible by using MVR technology is significant. ANDRITZ MVR evaporators are designed to operate with very low specific energy consumption while producing clean condensate to minimize fresh water consumption in the mill.
MVR evaporation plant 3d design
MVR evaporator
ANDRITZ MVR evaporators (sometimes referred to as a Vapor Compression Evaporator) removes water from mill liquors or effluents with minimum energy consumption and maximum plant availability while delivering high condensate quality.
The evaporators have lamella heating surfaces. Inherently non-foaming, these evaporators are ideally suited for the low dry solids applications of MVR evaporation with capacities from 10 to 200 t/h in a single unit.
MVR evaporators operate on a “heat pump” principle. The evaporated water vapor is recompressed with a simple, low-speed centrifugal fan or compressor which increases the saturation temperature of the vapor. After the fan, vapor can be used as heating steam in the same unit. The recompressed vapor condenses and releases its latent heat through the heat transfer surface for further evaporation of the liquor or effluent.
Compared to multiple-effect evaporators, MVR evaporators consume considerably less energy.
Low vapor velocities inside the evaporator, low shear rates, and the free flow falling film construction are advantages of the ANDRITZ design in minimizing foam creation. This is especially important in MVR evaporators, not only to maximize the production of clean condensate, but also for protection of the compressor or fan.
Uniform liquor distribution of the liquor over the lamellas, and the continuous redistribution of the liquor created by the dimpled shape of the lamella surface, ensure a completely wetted heating surface and eliminate local scaling or over-concentration of liquor. The lamella 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.
Highly efficient condensate segregation in the evaporator ducts and lamellas, plus the integrated stripping of foul condensate fractions, produce clean and re-usable water. Methanol in the liquor is separated from the condensate and recovered as an auxiliary fuel in an ANDRITZ methanol liquefaction system.
