Falling film evaporator advantages and disadvantages

 Falling film evaporator advantages

Falling film evaporator is widely used in industrial, chemical, biochemical, and other fields. Falling film evaporator is so popular in the market because it has several essential advantages, they are 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 evaporator disadvantages

Even though there are many advantages of falling film evaporator, there are still some disadvantages of falling film evaporator, for example:

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 evaporator is not applicable to materials that are prone to fouling or contain solid suspended matter.

Difference between rising and falling film evaporator

Falling film evaporator and rising film evaporator are both devices used to concentrate or extract substances. There some differences between them:

1) Falling film evaporator can evaporate substances that are higher-concentration, higher-viscosity, and heat-sensitive substances.

2) The working system of falling film evaporator is different from rising film evaporator’s working system. During falling film evaporator’s working, liquid goes from the top to the bottom. Whereas, during the rising film evaporator’s working, liquid goes from the bottom to the top.

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