Demister

Project Description

Role of Demister in Cooling Towers

A demister is commonly used when drift and moisture carryover must be strictly controlled. In cooling tower systems, it is installed to separate water droplets from exhaust air and return them to the circulation system. Engineers often choose demisters when environmental regulations or nearby sensitive equipment require better moisture control.

Working Mechanism

Moist air passes through specially designed passages inside the demister. These passages force the airflow to make several sharp turns. Water droplets cannot change direction as easily as air, so they collide with the surface and drain away by gravity.

Key Advantages

High Separation Efficiency

Compared with simple drift eliminators, demisters can achieve very low moisture carryover when designed correctly. This makes them suitable for applications with higher control requirements.

Compact Design

Demisters are usually compact in structure, which makes them easier to install in cooling towers with limited space.

Materials and Durability

Plastic materials such as PP are widely used due to their corrosion resistance and light weight. In some industrial systems, stainless steel demisters are applied when higher mechanical strength is needed, although plastic is more common in cooling towers.

Structural Forms

Blade-type demisters are the most common in cooling tower applications. Mesh-type demisters are also available and provide higher droplet capture efficiency, but they tend to accumulate dirt faster and require more frequent maintenance.

Selection Considerations

When selecting a demister, factors such as airflow volume, temperature, and available installation space should be considered. An over-designed demister may cause unnecessary pressure drop, while an under-designed one may allow moisture to escape.

Performance and Energy Use

The ideal demister design minimizes pressure loss while maintaining effective moisture separation. This balance helps reduce fan energy consumption while still achieving good environmental control.

Maintenance and Service Life

Regular inspection is recommended to check for blockages, scaling, and mechanical damage. Cleaning with low-pressure water can restore airflow channels. With proper maintenance, demisters can provide long service life and stable performance.