Falling Film Evaporator
Falling film evaporators concentrate liquid products by removing part of their water at a relatively low temperature. The liquid enters from the top and spreads over the inside of the heat-exchange tubes as a thin film, then flows downward under gravity. Since the film is thin and moves quickly, heat reaches the liquid efficiently without keeping it hot for a long time. The evaporator works under vacuum, which lets the liquid boil at a lower temperature and is gentler on heat-sensitive products. As water is removed and the liquid becomes thicker, it continues to flow down the tubes as a thin film, helping the product move smoothly and reducing the risk of uneven heating.
| Model | |||||
| Water Evaporation Capacity (kg/h) | 500-2000 | 1200 -5000 | 3600-20000 | 12000-50000 | 20000-120000 |
| Feed Concentration (%) | According to product characteristics | ||||
| Final Product Concentration (%) | According to product characteristics | ||||
| Steam Pressure (MPa) | 0.05-0.1 | 0.6-0.8 | |||
| Specific Steam Consumption (kg steam/kg evaporated water) | 1.13 | 0.38 | 0.28 | 0.28 | 0.23 |
| Evaporation Temperature (℃) | 48-90 | ||||
| Sterilization Temperature (℃) | 86-110 | ||||
| Cooling Water Consumption (t of cooling water/t of evaporated water) | 28 | 9-14 | 7-9 | 6-7 | 5-6 |
The liquid enters from the top of the evaporator and is spread into a thin layer along the inside of the tubes. As this thin film flows downward, heat from the outside of the tubes removes part of the water as vapor. The vapor and the more concentrated liquid then move into a separator, where they are split apart. In a single-effect system, the vapor goes to a condenser; in a multi-effect system, that vapor can be reused to heat the next evaporation stage. The concentrated liquid then leaves the separator and continues to the next process.
Falling film evaporators are widely used in food, pharmaceutical, chemical, biotechnology, environmental, and waste-liquid recovery processes. In food production, they are suitable for heat-sensitive or foaming liquids that need to be concentrated without staying at high temperature for too long.
The system can include the evaporator, separator, condenser, thermocompressor, vacuum pump, product pump, condensate pump, operating platform, electrical instruments, valves, and piping.
- Steam heats the liquid quickly and evenly, so it does not stay hot longer than necessary.
- In a multi-effect evaporator, the vapor from one stage can be used again in the next stage, which cuts down on fresh steam use.
- The falling-film design also works well with liquids that foam easily because most of the liquid leaves the heating tubes before reaching the separator, so the product moves through the evaporator more gently and less foam forms.
- Juice and dairy products can be sterilized before concentration. They are heated to about 90–125℃ for 30–60 seconds before entering the evaporator, where flash evaporation quickly brings the temperature down.
- Thanks to CIP (cleaning in place) system the evaporator and piping be cleaned without taking them apart, and the internal surfaces are easy to reach and clean.
