Agitated Thin Film Evaporator
The agitated thin film evaporator is the right answer modern technology has to offer to solve the difficult problems posed by heavy organic products, having high viscosity and being very sensitive to high temperature. The molecular distiller falls within this line, and in it, the condenser is placed inside the evaporator, in order to shorten up the passage of vapors and eliminate any clogging during its passage to the refrigerating tubes.
The agitated thin film evaporator has a rotating distributor that throws lecithin containing 30 to 50 % humidity, towards the hot vertical wall, by means of centrifugal force. A dynamically balanced agitator, commanded by a motor reducer, has a number of blades that rotate near the heating surface closely enough to let a thin film form. This device is particularly fit for viscous liquids and no Newtonian ones as lecithin, the reological features. Lecithin humidity produced is less than 1%. Vapours produced go through a drop separator and are transported to the vacuum system.
This agitated thin evaporator creates a thin film and a special turbulence before the blades than rotate very fast, which increases the heat transference coefficient compared to traditional systems. On the other hand, the residence time of the product when in contact with the hot surface is minimum, what happens to be particularly important when dealing with organic substances sensitive to moderate temperatures. The evaporator vacuum works and the vacuum is produced by a three stage ejector system, so that the thin film temperature does not rise beyond 100ºC. This unit has a capacity of 100 ton/day of dry lecithin. If a larger capacity is required, then two or more parallel evaporators.
Plants with agitated thin film evaporators have the following advantages over the traditional discontinuous ones: Steady functioning, involving considerable time saving, because there are no charge and discharge operations that call for down time. The whole plant can be automated. Minimum residence time in contact with hot walls, which results in better product quality. The plants occupies little space.