Levén evaporator

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The characteristic of the Levin evaporator is that a boiling chamber is added above the heating chamber. In this way, the solution in the heating chamber, under the influence of this additional liquid column, can vaporize only when it reaches the boiling chamber. A vertical partition is installed above the boiling chamber to prevent bubbles from growing. Furthermore, since the circulation tube is not heated, the driving force for solution circulation is greater. The height of the circulation tube is generally 7–8 m, and its cross-sectional area is about 200–350% of the total cross-sectional area of the heating tubes. As a result, the flow resistance inside the circulation pipe is low, and the circulation speed can reach up to 2 ~3 m/s. The advantages of the Levin evaporator are its high circulation speed and excellent heat transfer performance. Since the solution does not boil inside the heating tubes, crystal formation within those tubes can be avoided; therefore, it is suitable for processing solutions that tend to form crystals or suffer from scaling. Its drawback is that the equipment is large and requires a high factory building. Furthermore, due to the high static pressure of the liquid layer, a higher pressure for the heating steam is required.