falling film evaporatorIt is to add the feed liquid from the upper tube box of the heating chamber of the falling film evaporator, distribute it evenly into each heat exchange tube through the liquid distribution and film forming device, and flow from top to bottom in a uniform film shape under the action of gravity, vacuum induction 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 sufficient separation of the vapor and liquid, the steam enters the condenser for condensation (single-effect operation) or enters the next-effect evaporator as the heating medium, So as to realize multi-effect operation, the liquid phase is discharged from the separation chamber.

The feed liquid of the falling film evaporator enters the feed liquid distributor from the top. The feed liquid distributor distributes the feed liquid evenly into each heating tube and makes it flow downward along the inner wall of the tube in a film shape, and the liquid film evaporates and vaporizes by the heat transferred from the tube wall. When the heat transfer temperature difference is not large, vaporization occurs on the inner surface of the strongly disturbed film, rather than on the interface between the heating tube and the liquid film (I. e., the inner surface of the heating tube), so it is not easy to scale. The steam produced usually flows down in parallel with the liquid film. Due to the large vaporization surface, the amount of liquid entrainment in the steam is small, and the feed liquid flows in a film shape on the inner wall of the pipe, which does not fill the entire section of the pipe, so the amount of feed liquid passing through can be very small.

The liquid distributor is a key component of the falling film evaporator, and the heat exchange intensity and production capacity of the falling film evaporator essentially depend on the uniformity of the liquid distribution along the heat exchange tube. By uniformly distributed it is meant that the liquid is not only uniformly distributed into each tube, but is also uniformly distributed along the entire periphery of each tube and maintains its uniformity over the entire length of the tube. When the feed liquid does not uniformly wet the inner surface of all heating tubes, the surface of the missing or less liquid may scale due to evaporation, and the scale surface in turn blocks the flow of the liquid film and further deteriorates the heat transfer conditions in the adjacent area.

Performance characteristics:

(1) The feed liquid of the falling film evaporator is added from the top of the evaporator, and drops along the tube wall under the action of gravity, and evaporates and increases concentration in the process, and the concentrated liquid is obtained at the bottom. Falling film evaporator can evaporate materials with high concentration and high viscosity.

2) Because the solution flows in a film shape in the single-pass evaporator, the heat transfer coefficient is higher.

3) The residence time is short, it is not easy to cause material deterioration, and it is suitable for processing heat-sensitive materials.

4) The liquid retention is small, and the falling film evaporator can operate quickly according to the changes of energy supply, vacuum degree, feed rate, concentration, etc. near constant,

5) Since the process fluid only flows under the action of gravity, rather than being pushed by the high temperature difference, low temperature difference evaporation can be used.

6) Falling film evaporator is suitable for evaporation and concentration of foaming materials. As the feed liquid evaporates in a film-like manner in the heating tube, vapor-liquid separation is formed. At the same time, at the bottom of the effect body, most of the feed liquid is pumped away. Only a small part of the feed liquid and all secondary steam enter the separator to strengthen the separation. The feed liquid integration process does not form too much impact and avoids the formation of foam.

Scope of application:

Falling film evaporator is widely used in medicine, food, chemical industry, light industry and other industries of water or organic solvent solution evaporation concentration, and can be widely used in the above industry waste liquid treatment. Especially suitable for heat-sensitive materials, the equipment under vacuum low temperature conditions for continuous operation, with high evaporation capacity, energy saving, low operating costs, and can ensure that the material in the evaporation process invariant.