ZEDIVAP effluent evaporators
The ANDRITZ Zero Effluent Discharge Evaporator (ZEDIVAP) is designed for very demanding effluent evaporation applications.
Processing difficult and dilute effluents with minimum overall energy consumption and maximum plant availability and condensate quality.
The ZEDIVAP evaporator uses a proven lamella-type heating surface configured to resist the often very difficult scaling and fouling conditions of effluent with high fiber content.
ZEDIVAP is the name for technologies ANDRITZ uses to recycle pulp mill effluents so that they can be re-used in the process. All the technologies use evaporation as the main water separation process. ZEDIVAP evaporators use a combination Mechanical Vapor Recompression (MVR) or Multiple Effect Evaporation (MEE) principles custom tailored to achieve minimum operating costs for each unique mill condition.
- Water recovery and COD/BOD removal from debarking and wood room effluents
- Water recovery and colour and COD/BOD removal from bleach plant effluents
- 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 effluents
- Water recovery and COD/BOD removal from semi-mechanical pulping effluents
Best possible energy efficiency
The combination of MEE and MVR evaporators results in minimum overall energy consumption.
Inherently non-foaming design
Low vapour velocities inside the evaporator, low shear rates, and less foaming are achieved with the free flow falling film construction. This is especially important in MVR evaporation not only to maximize condensate re-use, but also for protection of the compression fan.
Uniform liquor distribution on the heating elements and continuous redistribution of the liquor by the dimpled shape of the surface ensure a completely wetted heating surface and eliminate scaling or liquor over-concentration. A special nozzle-type distribution system is used for the most demanding applications.
High efficiency condensate segregation in the evaporator ducts and lamellas, plus integrated stripping of foul condensate fractions produce clean and re-usable water. Separated methanol is recovered in a methanol liquefaction system.
- Very low overall energy consumption that can be tailored to utilize existing secondary heat sources
- Excellent condensate segregation
- Easy capacity control
- Proven in the most demanding applications from mechanical pulping to wood room effluent