A falling film evaporator is a highly efficient evaporation system widely used for concentrating solutions, recovering solvents, and treating industrial wastewater.

The system is particularly suitable for heat-sensitive materials because evaporation takes place under vacuum and the liquid has a very short residence time on the heating surface. This helps reduce thermal degradation while maintaining high evaporation efficiency.

During operation, the feed liquid enters the upper distribution section of the evaporator and is evenly distributed onto the inner surface of the heat exchange tubes. Under the combined effect of gravity and vacuum, the liquid flows downward as a thin and uniform film.

Heat supplied from the shell side causes the liquid film to evaporate continuously. The generated vapor and concentrated liquid enter the vapor-liquid separation chamber, where they are separated. The vapor can be condensed or used as the heating medium for the next effect in a multi-effect evaporation system.

Falling film evaporators are widely used in pharmaceutical, food processing, chemical, environmental protection, and industrial wastewater treatment applications.

Working Principle

The falling film evaporation process typically follows these steps:

Feed Liquid → Liquid Distribution → Thin Film Formation → Heat Transfer → Evaporation → Vapor-Liquid Separation → Concentrated Product

The feed liquid enters the top distribution system and is evenly distributed across the heat exchange tubes.

A thin liquid film forms on the inner wall of each tube and flows downward under gravity.

Meanwhile, the heating medium on the shell side transfers heat through the tube wall to the liquid film.

As the liquid flows downward:

• Heat transfer occurs continuously

• Part of the liquid evaporates

• The solution becomes increasingly concentrated

• The generated vapor flows into the separation chamber

The vapor and concentrated liquid are separated in the vapor-liquid separator.

Depending on the process configuration:

• The vapor can be condensed directly in a condenser, or

• Used as the heating medium for the next stage in a multi-effect evaporation system.

This design enables efficient evaporation with relatively low energy consumption.

Product Specifications

Technical parameters can be customized according to process conditions and customer requirements.

Main Components

A typical falling film evaporator system consists of:

Feed Distribution System

Ensures that the incoming liquid is evenly distributed across the heat exchange tubes.

Uniform liquid distribution is essential for maintaining stable film formation and efficient heat transfer.

Heating Chamber

The heating chamber contains heat exchange tubes where the liquid forms a thin falling film.

Heat is transferred through the tube wall, causing partial evaporation of the liquid.

Vapor-Liquid Separator

Separates the generated secondary vapor from the concentrated liquid.

The separator design helps prevent liquid droplets from entering the vapor outlet.

Condenser

In a single-effect evaporation system, the generated vapor is condensed into liquid.

Multi-Effect Connection System

For multi-effect evaporation systems, the vapor generated from one effect can be used as the heating medium for the next effect.

This significantly improves overall energy efficiency.

Vacuum System

Maintains the required operating vacuum and reduces the boiling temperature of the process liquid.

This is particularly important when processing heat-sensitive materials.

Key Features

High Heat Transfer Efficiency

The liquid forms a thin and uniform film on the heat exchange surface.

This reduces thermal resistance and provides a high heat transfer coefficient.

Compared with conventional bulk boiling systems, falling film evaporation can achieve efficient heat transfer with a relatively small temperature difference.

Short Residence Time

The liquid flows continuously through the heat exchange tubes.

This results in a short residence time at elevated temperatures.

The short thermal exposure helps reduce:

• Thermal degradation

• Product discoloration

• Changes in chemical composition

• Loss of heat-sensitive components

This makes falling film evaporators particularly suitable for temperature-sensitive materials.

Suitable for Vacuum Operation

Falling film evaporators can operate under vacuum conditions.

Vacuum operation reduces the boiling temperature of the process liquid, allowing evaporation at relatively low temperatures.

Advantages include:

• Reduced thermal damage

• Improved product quality

• Lower operating temperatures

• Suitable processing of heat-sensitive materials

High Evaporation Capacity

The continuous thin-film design provides a large effective heat transfer area.

The system can achieve high evaporation efficiency while maintaining stable operation.

Low Liquid Hold-Up

The volume of liquid retained inside the evaporator is relatively small.

This provides several advantages:

• Faster process response

• Easier process control

• Reduced material residence time

• Reduced product degradation risk

Suitable for Concentrating Solutions

As the liquid flows downward through the heat exchange tubes, water or solvent continuously evaporates.

The solution concentration gradually increases.

Falling film evaporators are suitable for concentration processes involving:

• Salt solutions

• Chemical solutions

• Organic solutions

• Process liquids

• Industrial wastewater

The actual applicable viscosity range depends on the liquid distribution performance, heat transfer characteristics, and final concentration requirements.

Energy-Saving Operation

Falling film evaporators can be integrated into multi-effect evaporation systems.

The secondary vapor generated from one effect can be reused as the heating medium for the next effect.

This significantly improves steam utilization and reduces overall energy consumption.

System Characteristics

1. Uniform Liquid Distribution

The feed liquid enters from the top of the evaporator and is evenly distributed onto the heat exchange tubes.

A stable liquid film is formed along the inner wall of the tubes.

Uniform distribution improves:

• Heat transfer performance

• Evaporation efficiency

• Operating stability

2. High Heat Transfer Coefficient

Because the liquid flows as a thin film rather than a large liquid volume, thermal resistance is reduced.

This allows efficient heat transfer between the heating medium and the process liquid.

3. Short Processing Time

The material passes through the heating surface quickly.

This minimizes exposure to elevated temperatures and helps protect heat-sensitive products.

4. Flexible Operating Conditions

The system can respond relatively quickly to changes in:

• Feed flow rate

• Feed concentration

• Heating steam supply

• Vacuum conditions

• Evaporation capacity

This provides good operational flexibility for industrial processes.

5. Low Temperature Difference Operation

Because of the high heat transfer efficiency and vacuum operating conditions, falling film evaporators can operate with relatively small temperature differences.

This improves energy efficiency and reduces thermal stress on sensitive products.

6. Suitable for Foaming Materials

The evaporation process mainly occurs inside the heat exchange tubes.

The vapor and concentrated liquid are then separated in a dedicated separation chamber.

With proper separator design and operating conditions, the system can reduce excessive foam generation and minimize liquid entrainment.

Applications

Chemical Industry

Falling film evaporators are widely used for:

• Chemical solution concentration

• Salt solution evaporation

• Acid and alkali solution processing

• Solvent recovery

• Process liquid concentration

Material selection can be customized according to the chemical composition and corrosion conditions of the process medium.

Pharmaceutical Industry

Suitable for:

• Heat-sensitive pharmaceutical solutions

• Concentration of active ingredients

• Solvent recovery

• Process wastewater treatment

The short residence time and vacuum operation help protect temperature-sensitive products.

Food & Beverage Industry

Applications include:

• Fruit juice concentration

• Dairy processing

• Sugar solution concentration

• Food ingredient concentration

• Flavor and extract processing

Low-temperature evaporation helps reduce thermal damage to sensitive food products.

Environmental Protection

Falling film evaporators are widely used in industrial wastewater treatment systems.

Typical applications include:

• High-salinity wastewater concentration

• Brine concentration

• Zero Liquid Discharge (ZLD) systems

• Industrial wastewater volume reduction

• Resource recovery

Salt & Chlor-Alkali Industry

Suitable for the concentration and treatment of:

• Brine

• High-salinity process solutions

• Chloride-containing wastewater

• Salt chemical process liquids

For highly corrosive chloride environments, equipment materials can be selected according to the specific temperature and chemical composition.

Material Options

The material of the falling film evaporator can be selected according to the process medium and operating conditions.

Available materials include:

• Titanium Gr1

• Titanium Gr2

• Titanium Gr7

• Titanium Gr12

• Stainless Steel 304

• Stainless Steel 316L

• Duplex Stainless Steel 2205

• Super Duplex Stainless Steel

• Titanium-Steel Clad Plate

• Nickel Alloys

For highly corrosive media, titanium and titanium alloy materials can provide excellent corrosion resistance and long-term service performance.

Quality Control

Each falling film evaporator can be manufactured and inspected according to customer specifications and applicable pressure vessel requirements.

Typical inspection procedures include:

Material Inspection

• Chemical composition verification

• Mechanical property testing

• Material traceability

• Material Test Certificates

Welding Inspection

• Welding procedure qualification

• Welder qualification

• Visual inspection

• Dye Penetrant Testing (PT)

• Radiographic Testing (RT), if required

Pressure Testing

• Hydrostatic pressure testing

• Leak testing

Dimensional Inspection

Verification of:

• Equipment dimensions

• Tube dimensions

• Nozzle orientation

• Flange connections

• Internal components

Surface Treatment

Stainless steel components can undergo:

• Pickling

• Passivation

Titanium components can undergo appropriate surface cleaning and treatment according to process requirements.

Advantages of Falling Film Evaporation Technology

• High evaporation efficiency

• High heat transfer coefficient

• Short residence time

• Suitable for heat-sensitive materials

• Low liquid hold-up

• Suitable for vacuum operation

• Energy-saving multi-effect configuration

• Stable continuous operation

• Good process flexibility

• Suitable for industrial wastewater concentration

• Can be customized for corrosive process media

Customized Falling Film Evaporator Solutions

We provide customized falling film evaporation equipment according to customer process requirements.

Customization options include:

• Single-effect evaporator

• Multi-effect evaporator

• Vacuum evaporation system

• Brine concentration system

• Wastewater treatment system

• Zero Liquid Discharge (ZLD) system

• Titanium heat exchange components

• Titanium-clad pressure vessels

• Customized heat transfer area

• Customized evaporation capacity

The equipment design can be optimized according to:

• Feed composition

• Feed concentration

• Required final concentration

• Evaporation capacity

• Operating temperature

• Operating pressure

• Corrosion conditions

• Energy consumption requirements