Thin film dryers are characterized by a mechanically agitated thin product layer inside the dryer (Fig. Thin Film Dryer). Normally, the drying process in a vertical thin film dryer consists of a preheating, a slurry and a powder zone. In the preheating zone the product reaches boiling point. Evaporation starts and solids are formed. In the slurry zone, the concentration of solids increases. Many products during this phase tend to form agglomerates which are crushed by the pendulum blades. In the final powder zone surface moisture is further removed and the drying process is completed.
The length of the various zones depends for a given product largely on the feed rates and feed moisture content.
The concentrated product from MEE is the feed to this system. The equipment consists of a cylindrical shell of jacketed for steam heating. The inside of the shell in is used for heat transfer surface. A Cylindrical rotor of rotating at a speed of 150 rpm shall be mounted inside the shell. Concentric with the shell axis. Teflon scrappers specially designed for evaporation in the initial portion and the drying at the bottom portion. The vapors generated shall be discharged to the surface condensers from the top of the dryer. The thick sludge of the product shall be discharged at the bottom.