Fundamental:

        The film formation of the feed liquid in the falling film evaporator is completely different from that of the rising film evaporator. As shown in the figure below, there is a feed liquid distributor on the top of the falling film evaporator. Its function is to evenly distribute the feed to each falling film evaporator. The membrane tube ensures that the liquid in each falling film tube flows down the tube wall in the state of a liquid film. The flow of the feed liquid in the falling film tube is carried out under the action of gravity and secondary steam flow. Since it is not the secondary steam that overcomes the gravity of the material liquid to push upward to form a film, but the material liquid evaporates while flowing downwards. At the bottom of the falling film tube, the material liquid and the secondary steam are basically separated, so the secondary steam entrains the material. The phenomenon of liquid is greatly improved, and the film distribution and evaporation of the material liquid in the heating tube are more stable and orderly. The aspect ratio of the falling film tube is between 100-250, and the tube diameter is generally between 38-50mm.

System Composition:

        The system includes evaporator, separator, condenser, vacuum and drainage system, various effects of liquid, transfer pump, operating platform, electrical instrument control cabinet and valves, pipelines, etc.

Technical Features:

At present, the most widely used in practice is the falling film evaporator. This is because the falling film evaporator has low heating temperature, fast evaporation rate, large heat transfer coefficient, short residence time of materials in the equipment, and good energy saving effect.

   ● Low evaporation temperature, up to 45-55℃, especially suitable for materials that are not easy to scale, easy to evaporate or have strong heat sensitivity.

   ● The concentration ratio is large, the concentration time is short (6-10min), and the concentration can be completed by one falling film evaporation.

   ● The flow rate of the pump is relatively small, the installed power is small, and the power consumption is low.

   ● The material and liquid undergo vapor-liquid separation at the bottom of the evaporator, and then enter the separator for separation, which enhances the separation effect.

   ● A film cloth device is set on the top of the evaporator to ensure that the material liquid is evenly distributed in the film tube of the evaporator to form a film, with a large heat transfer coefficient and high evaporation efficiency, which can prevent the "dry wall" phenomenon.

   ● There is no liquid column in the heating tube, and there is no temperature loss due to the static pressure of the liquid column. Each effect only needs to operate at a low heat transfer temperature difference (5-9°C), with high heat transfer efficiency and evaporation intensity big.

   ● Special design allows efficient switching changed to adapt to different products.

   ● Equipped with CIP cleaning pipeline in the equipment, which can realize in-situ cleaning.

Various Types of Falling Film Evaporator：

1. Tubular Falling Film Evaporator

        The tubular falling film evaporator is to add the material liquid from the upper pipe box of the heating chamber of the falling film evaporator, and distribute it evenly into the heat exchange tubes through the liquid distributor, and flow into a uniform film from top to bottom under the action of gravity and airflow. During the flow process, it is heated and vaporized by the shell-side heating medium, and the generated steam and liquid phase enter the separation chamber of the evaporator together. After the vapor and liquid are fully separated, the secondary steam and concentrated liquid are discharged respectively.

 2.Plate Falling Film Evaporator

        The plate-type falling film evaporation uses hollow plates as heat exchange elements. The liquid passes through the liquid distributor on the upper part of the heater group. A liquid film is formed on the outer surface of each plate and flows downward by gravity. During the flow, the heating medium in the plate cavity After heating and vaporization, the secondary steam generated enters the shell, and is discharged after the mist is separated. The concentrated liquid enters the bottom of the shell and is discharged.

3. Forced Falling Film Evaporator

        The forced falling film evaporator is a common falling film evaporator with a large flow circulating pump to increase the thickness of the liquid film, reduce fouling, and reduce and prevent the "dry wall" phenomenon.

4. MVR Falling Film Evaporator

The material liquid is added from the top of the evaporator and flows down the tube wall in a film-like manner under the action of gravity. During this process, the material liquid is continuously evaporated and concentrated, and the finished liquid is obtained at the bottom of the heat exchanger. After the generated secondary steam is separated in the separator, it enters the MVR compressor, and after compression to do work, the temperature and pressure of the secondary steam rises, and it is used as a new heat source to heat the raw material liquid.

Application range:

        The falling film evaporator designed by Jiangsu Heide has the characteristics of low heating temperature, fast evaporation rate, short residence time in the equipment, and good energy saving effect. It has been widely used in food, dairy, light industry, chemical, pharmaceutical, etc. In the industry, if the evaporative concentration of vegetable juice, milk, egg products, sugar liquid, vitamin C, collagen, traditional Chinese medicine, sodium glutamate, papermaking black liquor and other materials, it is also particularly suitable for the evaporative concentration of heat-sensitive substances.