Benefits
- Very low energy consumption that can utilize existing secondary heat sources
- Excellent condensate segregation
- Easy capacity control
- Proven in the most demanding applications from mechanical pulping to woodroom effluent
ANDRITZ effluent evaporator
The ANDRITZ ZEDIVAP evaporator (Zero Effluent DIscharge Evaporator) utilizes lamella-type heating surface for the demanding effluent evaporation applications.
The ANDRITZ zero effluent discharge evaporator is designed to recover and recycle pulp or paper mill effluents. With effluent evaporator technology, even difficult and dilute effluents can be processed to recover water for the process. In many cases, the remaining concentrated effluent stream can be further processed to recover valuable process chemicals.
Design
The evaporator uses tested and proven lamella heating surfaces to evaporate water from even the most difficult or dilute effluent streams with minimal energy consumption. The lamellas are ideally suited to resist potential scaling or fouling, even with effluents that have high fiber content.
The evaporators use Mechanical Vapor Recompression (MVR) and/or multiple-effect evaporation principles which are custom-tailored to achieve minimum operating costs for each unique mill condition.
Applications
- Water recovery and COD/BOD removal from debarking and woodroom effluent
- Water recovery, color, and COD/BOD removal from bleach plant effluent
- Recovery of incompatible process elements (e.g. sodium in bleach plant effluent from Ca-based mills)
- Water recovery and COD/BOD removal from mechanical pulping effluent
- Water recovery and COD/BOD removal from semi-mechanical pulping effluent
Best possible energy efficiency
The correct combination of evaporation principles (MVR and MEE) is engineered to minimize energy consumption.
Non-foaming design
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.
Non-plugging design
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.
Cleanest condensates
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.
