How A Thin Film Evaporator Works
Diluted process material (purple) is introduced into the tangential feed inlets above the thermal body section. The material is then evenly distributed over the internal wall of the evaporator by means of a distribution ring that is an integral part of the evaporator rotor. As gravity draws the process material downward into the heated thermal sections, the rotor blades keep the material spread over the heated surface creating effective film turbulence. This turbulence, which has been intentionally designed into the evaporator, continually re-exposes all of the process material to the heated surface. The continual rotation of process materials prevents localized over-heating and thus helps to prevent the “fouling” of the evaporator. Since the evaporator provides a condition of high heat transfer and short residence time, rapid vaporization is attained. At extremely low bottom output rates, an additional ring may be installed in the bottom of the thermal section to increase residence time. This ring effectively acts as a dam, causing the process flow to backup into the lower portion of the thermal sections insuring proper process wetting in the heated vessel wall. The resultant escaping vapors (blue) travel upward toward the vapor outlet, being separated from the incoming feed by the distribution ring. Liquids, entrained in the vapor steam, are trapped in the vapor section and drain back into the thermal bodies. The “liquid free” vapors pass through the vapor outlet ready to be condensed. Meanwhile, the non-volatile processed product or residue (red) passes from the thermal bodies to a bottoms cone and is discharged.