Scraper Evaporator

Scraper evaporator, which is a highly adaptable new type of evaporator, for example for high viscosity, heat sensitive and easy to crystallize and scale materials. It is mainly composed of a heating jacket and a scraper. The jacket is heated by steam. The scraper is mounted on a rotatable shaft. The scraper and the inner wall of the heating jacket are kept at a small gap, usually 0.5 to 1.5 mm. After the preheating, the liquid is added from the upper part of the evaporator in the tangential direction. Under the action of gravity and rotating scraper, the lower rotating film is distributed on the inner wall, and is continuously evaporated and concentrated during the descending process, and the finished liquid is discharged from the bottom. The secondary steam escapes from the top. In some cases, this evaporator evaporates the solution to give a solid product directly at the bottom.

The material continuously enters the horizontal evaporator from the large diameter end, is accelerated and dispensed by the wiper blade and immediately forms a thin flowing film on the heating surface. The conical thin film evaporator relies on the centrifugal force applied to the material by the rotor. This centrifugal force has two effective forces, one perpendicular to the heating surface and the other toward the large diameter end body (note: the same result also appears in the vertical conical type). In the thin film evaporator, the force is generated by these forces, and the incoming material ensures that the heating surface is sufficiently wet and does not depend on the evaporation ratio or the feed rate. Therefore, local material overheating and thermal degradation are reduced or completely eliminated.

During this process, the light component (low boiler) flows downstream (and the liquid film in the same direction) through the horizontal thin film evaporator into the vapor-liquid separator where the droplets and foam generated by vapor-liquid separation are Crushed into the liquid phase (high boiler), the separated vapor enters the external condenser or the next process; the reconstituted fraction (high boiler) climbs along the heated wall to the small end outlet.