The rising membrane evaporator is structured such that liquid enters the heating tubes via the principle of a siphon pump for heating. After flowing into the separator, the liquid is separated from the vapor, then returns to the evaporator through a circulation pipe, forming a closed-loop cycle. Therefore, this type of evaporator is also known as an external circulation evaporator. The heating tubes are composed of heat exchange tubes. After the raw material liquid is preheated to its boiling point or near the boiling point, it is introduced from the bottom of the heating chamber. Driven by the high-speed rising secondary vapor, the liquid flows along the inner wall of the heat exchange tubes while evaporating. The required concentration is achieved at the top of the heating chamber, and the finished liquid is discharged from the bottom of the separation chamber. The generated secondary vapor passes through the separation plate group set at the upper part to remove bubbles, water droplets, and impurities, becoming the heat source for the next effect.
The rising membrane evaporator is suitable for processing solutions with large evaporation capacity, thermal sensitivity, low viscosity, and easy foaming. However, it is not suitable for solutions with high viscosity, crystal precipitation, or easy scaling. It is applicable to the evaporation of substances with large evaporation capacity, thermal sensitivity, viscosity, and foaming properties. Due to the extremely short residence time in single-pass operation, it can be used as a high-concentration evaporator.
