Screw Type Evaporator

Application Scope
Widely used in the oil and chemical industries, particularly suitable for high-viscosity materials (such as gum, honey, etc.) that are prone to crystallization, scaling, and thermal sensitivity.
Material continuously enters the horizontal evaporator from the large diameter end, accelerated and distributed by the scraper blade, and immediately forms a thin [1] flowing film on the heating surface. The conical film evaporator, relying on the centrifugal force applied to the material by the rotor, has two effective forces: one perpendicular to the heating surface and the other directed towards the large diameter end (note: the same result also occurs in vertical cone-shaped film evaporators). These forces produce material acceleration, and the incoming material ensures the heating surface is sufficiently moist, independent of the evaporation ratio or feed rate. Therefore, local material overheating and thermal degradation are reduced or completely eliminated.
During this process, the light components (low boiling substances) flow in the same direction as the liquid film through the horizontal film evaporator into the vapor-liquid separator. Here, the liquid droplets and foam produced by the vapor-liquid separation are shattered and enter the liquid phase (high boiling substances), while the separated vapor enters the external condenser or the next process. The heavy components (high boiling substances) climb along the heated wall to the small end outlet and are discharged.

Working Principle

The evaporator shell is equipped with a heating steam jacket internally, containing rotatable blades or scrapers. The scrapers come in two types: fixed and rotor-style, with the former having a gap of 0.5 to 1.5mm between the shell's inner wall, and the latter's gap varies with the speed of the rotor. The feed liquid is added to the upper part of the evaporator along the tangent direction (or to a spinner disk coaxial with the scrapers). Due to gravity, centrifugal force, and the scraping action of the rotating blades, a downward spiraling film forms on the inner wall of the evaporator, which is then evaporated and concentrated during this process. The liquid is then discharged from the bottom. This type of evaporator is a single-pass evaporator that utilizes external power to form the film.

Equipment specifications and main parameters