Falling Film Evaporators’ Advantages
Falling film evaporators are widely used in industrial, chemical, biochemical, and other fields. Falling film evaporators are so popular in the market because it has several essential advantages, mainly as follows:
1) The material in the heat exchange tube is in the form of a film and has a fast flow rate, so the evaporation heat transfer coefficient is large;
2) Since the pipe material flows downward along the inner wall of the pipe by its own gravity, instead of pushing with the pressure difference, the low temperature difference can be selected;
3) After the tube material is heated, it exhibits convection boiling, so the surface state of the heat exchange tube hardly affects the boiling of the material.
Falling Film Evaporators’ Disadvantages
Even though there are many advantages of falling film evaporators, there are still some disadvantages, such as:
1) It is necessary to ensure that the inner wall of the heat exchange tube of the equipment is completely wet but the membrane is not too thick. It is necessary to carry out a very accurate design calculation of the material feed amount and the length of the heat exchange tube to meet such requirements;
2) The equipment procurement cost is very high due to high design and manufacturing requirements;
3) Falling film evaporators are not applicable to materials that are prone to fouling or contain solid suspended matter.
Difference between the Rising and Falling Film Evaporator
The falling film evaporator and rising film evaporator are both devices used to concentrate or extract substances. There are some differences between them, as follows:
1) The falling film evaporator can evaporate substances that are higher-concentration, higher-viscosity, and heat-sensitive substances.
2) The working system of the falling film evaporator is different from the rising film evaporator’s working system. During the working of the falling film evaporator, liquid goes from the top to the bottom. Whereas, during the working of the rising film evaporator, liquid goes from the bottom to the top.