DRIFT LOSS
This is an undesirable loss that represents inefficiency.
- What it is: The physical carryover of tiny liquid water droplets by the exhaust air stream out of the tower. These are not evaporated.
- Cause: High-velocity air shears water into fine mist. Without proper controls, this mist is discharged from the tower.
- Key Characteristics:
- Visible: Often seen as a mist or plume near the tower (though the plume is primarily condensed vapor).
- Controllable: Minimized by Drift Eliminators – labyrinth-like devices that force air to change direction, causing droplets to impact and drain back.
- Negligible Thermal Benefit: Provides virtually no cooling.
- Carries Treatment Chemicals: The droplets contain the concentrated water treatment chemicals (biocides, corrosion inhibitors), leading to:
- Chemical Loss (increased costs).
- Environmental/Health Concerns (potential chemical drift onto people, property, or vegetation – a key concern for Legionella control).
- Impact on System: Wastes expensive treated water and chemicals. Does not contribute to concentration of solids (the droplets are at system COC, so their loss is similar to blow down but uncontrolled).