Role and Use of Drift Eliminators in Cooling Towers
Drift eliminators are critical components in cooling towers designed to minimize water loss and reduce environmental impact by capturing entrained water droplets from the exhaust air stream.
1. Purpose of Drift Eliminators
> Prevent Water Loss – Recovers water droplets that would otherwise escape as “drift.”
> Reduce Chemical Consumption – Prevents loss of treatment chemicals (e.g., biocides, corrosion inhibitors).
> Comply with Environmental Regulations – Limits discharge of contaminated water into surroundings.
> Improve Efficiency – Ensures water stays in the system for reuse.
2. How Drift Eliminators Work
- Mechanism:
- As air exits the cooling tower, it carries tiny water droplets (drift).
- Drift eliminators use baffles, zig-zag channels, or chevron designs to force air into directional changes.
- Water droplets impinge on the eliminator surfaces, coalesce, and fall back into the tower.
- Efficiency:
- High-performance eliminators can reduce drift loss to 0.001–0.005% of circulating water (vs. 0.1–0.2% without eliminators).
3. Types of Drift Eliminators
| Type | Design | Advantages | Disadvantages |
| Chevron (Blade-Type) | Angled baffles in a V-pattern | High efficiency, low airflow resistance | Requires precise installation |
| Waveform (Zig-Zag) | Curved, sinusoidal pathways | Good for high-velocity air streams | Slightly higher pressure drop |
| Mesh-Pad | Fine mesh or knitted material | Excellent for small droplets | Prone to clogging (needs cleaning) |
| Honeycomb | Cellular structured panels | Low maintenance, durable | Less efficient for fine droplets |
4. Key Benefits of Drift Eliminators
- Water Conservation – Saves thousands of gallons per year in large towers.
- Cost Savings – Reduces makeup water and chemical treatment expenses.
- Environmental Protection – Prevents spread of legionella, salts, and chemicals.
- Improved Air Quality – Reduces visible mist around cooling towers.
5. Factors Affecting Drift Eliminator Performance
- Air Velocity – Higher speeds increase drift; eliminators must match tower design.
- Fill & Fan Alignment – Poorly positioned fills/fans can increase drift.
- Material – PVC is common (lightweight, corrosion-resistant), while PP handles harsh chemicals.
- Maintenance – Clogged or damaged eliminators lose efficiency.
. Maintenance & Troubleshooting
> Inspect Regularly – Check for scaling, algae build-up, or physical damage.
> Clean Periodically – Use low-pressure water or approved cleaning agents.
> Replace if Damaged – Warped or cracked eliminators reduce efficiency.
Comparison: With vs. Without Drift Eliminator
| Scenario | Drift Loss (%) | Impact |
| No Eliminator | 0.1–0.2% | High water/chemical loss, environmental risks |
| Standard Eliminator | 0.005–0.01% | EPA-compliant, cost-effective |
| High-Efficiency | <0.001% | Best for strict regulations |