Mechanical Vapor Re-compression (MVR) is another technology for Evaporation for wastewater, which operates with the Heat Pump Principle.
Water Vapor evaporated from effluent is recompressed with a simple, low speed centrifugal fan. The fan increases the saturation temperature of the vapor and hence the vapor can be used for heating in the same effect. The recompressed vapor condenses and releases its latent heat through heat transfer surface for further evaporation of effluent.
Membrane Group’s MVR systems are operated under vacuum and typically boil water at 60 C. Since the evaporation takes place at lower temperature there is a much lower chance of organics carryover in the system. The complete system is compact, skid mounted and comes in various capacities as per the client requirement.
Key Advantages of Membrane Groups’ MVR Evaporator are: -
No/ Minimal requirement for Steam (only Startup) therefore much lower operating cost compared to MEE
Very Low specific energy consumption
Excellent condensate quality
No requirement for Cooling Water
Suitable to concentrate wide variety of liquor to very high level with minimum temp difference using tubular technology
Fully Automated PLC Based system
Eco-Friendly – eliminates boiler
Much Lower Opex compared to MEE
MVR Evaporators are typically used to concentrate effluent from a feed concentration of ~1-10% to 25%-35 and are available in various capacities. Post reaching a concentration of 35% the effluent has to be further treated in a Dryer/ Crystallization System to reach a concentration above 90% Solids and hence achieve ZLD. Membrane Group recommends and supplies Agitated Thin Film Dryer (ATFD) for this application wherein Dry baggable salts of less than 10% Moisture can be obtained on a continuous basis without any down time.
MVR Evaporators can also be used to pre-concentrate the effluent before feeding to Multi effect evaporator and can thereby drastically reduce the overall cost of operations.