Today, we’ll explore the significance of water quality management in cooling towers. Failure to manage the water quality circulating within a cooling tower can lead to issues such as microbial growth, corrosion, aging, and performance degradation. Therefore, effective water quality management is crucial for the operation and maintenance of a cooling tower. Here are some methods that can be adopted for water quality management.
- Blowdown
- Scale Prevention
- Corrosion Control
- Control of Biological Growth
1. Blowdown
Water evaporation occurs leaving behind dissolved solid residues(TDS) in a pure vapor state. Without any control, TDS in the circulating water will continue to increase persistently. This poses a risk not just to the cooling tower but to all parts involved in water circulation. Blowdown is a method to regulate TDS concentration. It involves continuously discharging a portion of the circulating water along with TDS residues and replenishing it with relatively pure makeup water. There are various methods for blowdown, but a common approach involves continuously discharging about 0.3% of the circulation rate through a drain valve. Despite the benefits of blowdown, chemical, electrostatic, and electronic treatment of water is necessary to prevent scale formation, corrosion, and biological growth.
2. Scale Prevention
The primary component causing scale formation in cooling towers is calcium carbonate, which has a solubility of approximately 15 ppm. It’s necessary to introduce designated compounds into the water, using water treatment facilities, to exclude solids that create scale from the solution.
3. Corrosion Control
Metals used in cooling towers are susceptible to corrosion in several ways. This can occur due to high levels of O2 and CO2, low pH, or contact between different metals. The increase in dissolved solids escalates conductivity and the potential for corrosion. Hence, blowdown can be considered a highly effective method not only for controlling scaling but also as a preventive measure against corrosion.
4. Control of Biological Growth
Within cooling towers, the growth of slime and algae can often be observed, potentially compromising cooling efficiency. Compounds containing chlorine or chlorine-based substances are effective in removing slime and algae. However, an excess of these substances can pose a risk of damaging other organic materials within the structure and wooden components
