The falling film evaporator stands out for its efficiency and gentle handling of heat-sensitive products, is suitable for solutions such as milk, glucose, oligosaccharides, sorbitol, fruit and vegetable juice, etc. It is widely used in the evaporation and concentration of aqueous solutions and organic solvent solutions in industries such as food processing, pharmaceuticals, deep processing of grain, bioengineering, environmental engineering, and etc.
Evaporation is a cornerstone process in many industries, from food and beverage to pharmaceuticals. And the falling film evaporator stands out for its efficiency and gentle handling of heat-sensitive products, is suitable for solutions such as milk, glucose, oligosaccharides, sorbitol, fruit and vegetable juice, etc. It is widely used in the evaporation and concentration of aqueous solutions and organic solvent solutions in industries such as food processing, pharmaceuticals, deep processing of grain, bioengineering, environmental engineering, and etc.
The falling film evaporator operates under vacuum conditions and utilizes a thin film of liquid that flows down the inside surface of heat exchange tubes, enhancing the heat transfer efficiency.
In the falling film evaporator, the feed is introduced through a distribution unit at the top of the heater, which disperses the liquid into each of the heat exchange tubes to form a thin film.under effect of gravity, vacuum and airflow, the films flows downwards. During this flow, the material is heated by the heating medium in the shell side and vaporizes. The resulting steam and liquid phase enter into the separator of the evaporator together, where they are fully separated. The steam goes to the condenser to be condensed (for single-effect operation) or enters the next-effect evaporator as heating medium (for multi-effect operation), while the liquid phase is discharged from the separator.
Single-effect falling film evaporator, multi-effect falling film evaporators (including double-effect, triple-effect, four-effect and five-effect), MVR (Mechanical Vapor Recompression) falling film evaporators, etc.
Falling film evaporators perform evaporation and concentration under vacuum and low-temperature conditions, with high evaporation efficiency, low energy consumption, and low operating costs, while largely maintaining the original components of the materials.
Falling film evaporators are versatile and used across various sectors, and the main applications include:
1) Food Industry: Concentrating milk, fruit and vegetable juices, syrups without damaging heat-sensitive nutrients.
2) Chemical Industry: Concentrating solutions, solvent recovery, and temperature-sensitive chemical reactions.
3) Pharmaceuticals: Drug concentration, solvent removal, maintaining the integrity of active pharmaceutical ingredients.
4) Waste Water Treatment: Concentrating effluents and enabling solvent recovery.
A typical falling film evaporator consists of the following components:
1) Heater: A heat exchanger that transfers heat to the product to cause vaporization.
2) Separator: A vessel where the vapor separates from the concentrated liquid.
3) Condenser: Where the vapor is condensed. When a large amount of secondary steam is condensed into liquid, the vacuum condition inside the system is formed, thus maintains the necessary operation pressure.
4) Vacuum System: Provides the system with an initial vacuum system.
5) Transfer Pumps: Including charging pump, discharging pump and condensate discharging pumps.
6) A thermo-compressor (optional): with a thermo-compressor, part of the secondary steam is sucked back into the shell side of the first-effect evaporator through the thermo-compressor, allowing for full utilization of the heat, characterized by low steam consumption and low cooling water circulation. Additionally, since steam entering the heating shell through the thermo-compressor is in a spray mist, it diffuses quickly, and the material is gently heated, so it’s suitable for the concentration of heat-sensitive materials.
7) CIP System (optional): Clean-in-Place system for easy and efficient cleaning.
8) For materials requiring sterilization, the sterilization and concentration processes can be completed in one step. The material is first preheated, then enters the sterilizer, and then enters the first-effect evaporator where it flash vaporizes, and the temperature drops instantaneously, suitable for concentration of heat-sensitive liquids.
9) A mechanical compression pump can be equipped, which is the MVR type falling film evaporator. All of the secondary steam is compressed and heated by the mechanical compression pump and then reintroduced into the shell side of the evaporator as the heating medium, utilizing heat fully, and characterized by low steam and cooling water consumption.
1) Efficiency: High heat transfer coefficients due to the uniform heating by steam and liquid film flow evaporation;
2) Low Temperature Operation: Suitable for heat-sensitive materials due to operating under vacuum, which lowers boiling points;
3) Energy Saving: Often used in multi-effect configurations or with Mechanical Vapor Recompression (MVR), reducing energy requirements;
4) Uniform Product Quality: Short residence time minimizes thermal degradation, ensuring quality;
5) Scalability: Can be designed for small-scale operations to large-scale industrial applications;
6) Automation: Can be fully automated for consistent performance and minimal manual intervention.
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