Evaporate Water from Aqueous Solutions

The TAF evaporators can be used for aqueous solutions that do not contain volatile substances. Corrosive solutions can be evaporated if polymeric materials of construction are used. Special temperature control systems are required when this is the case.
Dilute (<5% dissolved substances) are usually suitable for volume reduction by evaporation. Resulting concentrates can be further reduced in volume by small second stage evaporators that operate at higher temperatures.

Pre-treatment of wastes can extend the range of applicability for evaporation. Steps that can be used include pH adjustment, precipitation, coagulation/flocculation, carbon addition, oxidation, VOC adsorption and combinations of these treatments. The pre-treatment is usually simple and inexpensive.
Exhaust gases from boilers and diesel generators can be used to evaporate water. Direct gas to liquid contact also provides a "scrubbing" effect. This may be important when waste oils are used as energy source.
Low equilibrium temperature of evaporation process allows the use of synthetic adsorbents for VOC removal. Exit temperatures are typically in the 55°C -60°C range.
Picture shows an evaporator that utilizes hot waste gases from an annealing furnace as energy for evaporation of waste water. Hot gases (190°C) are drawn into the evaporator, and the humidity saturated cooler (55°C) gases are returned to the existing furnace exhaust.
The apparatus can be modified to operate as a condenser. Common corrosion problems in metal condensers can be eliminated by constructing the apparatus of polymeric materials.