The falling film evaporator has a wide range of applications and involves multiple industries. Its working principle is relatively simple: the liquid enters the heating chamber of the falling film evaporator, and through the liquid distribution and film forming device, it is evenly covered in each heat exchange tube. Under the influence of gravity, vacuum induction, and airflow, the liquid forms a uniform thin film and flows downward. During the flow process, the heating medium in the shell side heats the liquid, causing it to evaporate. The generated steam enters the separation chamber of the evaporator together with the unevaporated liquid. Here, the gas-liquid mixture is thoroughly separated, and the steam either enters the condenser for condensation (single effect operation) or serves as a heating medium to enter the next effect evaporator, completing the multi effect operation, while the liquid is discharged from the separation chamber. So, what are the characteristics of the evaporation system of a falling film evaporator?
1. Due to the film like flow of the solution in the one-way evaporator, the heat transfer coefficient is relatively high.
2. Short residence time, less likely to cause material deterioration, suitable for handling heat sensitive materials.
3. The liquid retention is small, and the falling film evaporator can quickly adjust according to changes in energy supply, vacuum degree, feed rate, and concentration, with almost constant operation.
4. Due to the fact that the process fluid flows only under the influence of gravity, rather than relying on a high temperature difference for propulsion, low temperature difference evaporation can be used.
5. The liquid in the falling film evaporator is injected from the top of the evaporator and flows downwards along the tube wall under the action of gravity, forming a thin film. During this process, the liquid gradually evaporates and concentrates, eventually collecting concentrated liquid at the bottom. This evaporator is suitable for processing high concentration and high viscosity materials.
6. The falling film evaporator is suitable for the evaporation and concentration of foaming materials. Due to the material evaporating in a thin film state inside the heating tube, the separation of gas and liquid is achieved. At the bottom of the equipment, most of the liquid material is extracted, and only a small amount of liquid material enters the separator together with all the secondary steam for enhanced separation. The whole process has less impact on the feed liquid, thus effectively avoiding the formation of foam.