Cooling towers are a critical component in many water systems, providing comfort or process cooling across a broad spectrum of technologies and applications. Cooling towers vary greatly in design and footprint, but all have the main goal to provide removal of waste heat from processes or building systems. Water treatment control parameters are critical to maintaining any cooling system to improve water and energy efficiency, maximize equipment life expectancy, reduce hazards, and minimize downtime
Many factors such as the system design, operating conditions, makeup water quality, chemical feed and control equipment, on-site monitoring program, and treatment chemicals are considered when specifying the control ranges for a cooling treatment program. Operation outside of these design control parameters can result in problems that:
- Increase operation, energy, water, and maintenance costs
- Damage the cooling and/or chiller system
- Result in system failure
The table below summarizes common cooling tower control tests and their importance to the water treatment program. Actual control tests conducted will vary based on site-specific requirements.
|
Sample
|
Test
|
Purpose
|
Consequences
|
Corrective Measures*
|
|
Raw Water
|
Conductivity |
Establish cooling tower blowdown control range, monitor changes in raw water, and calculate cycle of concentration. |
Impacts cooling tower blowdown and can indicate other water quality changes that may influence cooling tower operation. |
|
|
Total / Calcium Hardness
|
May help establish cooling tower control range and can be used to calculate cycles of concentration.
|
Changes may impact cooling tower control limits.
|
|
| Chlorides |
| Silica |
|
Total Alkalinity
|
May help establish cooling tower control range.
|
|
|
Cooling Tower Water
|
Conductivity
|
Used to monitor and control blowdown requirements.
|
Low levels (excessive blowdown) wastes water and treatment chemicals, and can lead to corrosion.
High levels (inadequate blowdown) can cause scale deposits and excessive fouling. Scale deposits can result in cooling system failure.
|
If low, blowdown should be reduced. Note: decreasing blowdown will increase the chemical levels.
If high, blowdown should be increased. Note: increasing blowdown will decrease the chemical levels.
|
| Calcium Hardness |
Used to calculate Langelier Saturation Index (LSI) to monitor calcium carbonate scaling potential. |
High levels can cause scale deposits and excessive fouling which can result in less efficient operation and system failure. |
If high, increase blowdown and/or troubleshoot acid feed, if applicable. |
| Total Alkalinity |
| pH |
Used to calculate Langelier Saturation Index (LSI) to monitor calcium carbonate scaling potential.
Used to monitor acid feed control if applicable.
|
Low pH can cause corrosion and iron deposits and result in equipment failure.
High pH can cause scaling in heat transfer areas.
|
If high and not using acid, increase blowdown.
If high or low and using acid, troubleshoot acid feed.
|
| Chlorides |
May be used to calculate cycles of concentration (unless elevated by chlorine-based biocides) and monitor corrosivity of water (if applicable). |
High levels increase corrosivity (e.g., mild steel, copper, stainless steels). |
If high, increase blowdown. |
| Silica |
May be used to calculate cycles of concentration and monitor silica scale forming potential. |
High levels of silica can lead to silica scale formation. |
If high, increase blowdown. |
| Inhibitor Actives (Phosphate, Phosphonate, Azole, Zinc) |
Used to monitor active scale and corrosion inhibitor levels. |
Low inhibitor levels can result in scale deposits and corrosion.
High inhibitor levels wastes chemicals and can result in deposits which can result in system failure.
|
Cycles of concentration must be considered in relation to inhibitor tests. If high or low, the inhibitor may also be proportionally high or low.
If inhibitor is low, increase feed rate.
(Note: Keep in mind the impact of other factors upon inhibitor level. For example, if phosphate requirements increase significantly in a soft water program, check for hard water.)
If inhibitor is high, decrease feed rate.
|
| Tracers (PTSA, Molybdenum) |
Used to monitor product levels. |
Low tracer levels can indicate low product dosage, which can lead to scale deposits and corrosion.
High tracer levels can indicate high product dosage, which can lead to wasted product, potential deposits, and corrosion.
|
Cycles of concentration must be considered in relation to the tracer. If high or low, the tracer may also be proportionally high or low.
If tracer level and inhibitor actives are low, increase feed rate.
If tracer level and inhibitor actives are high, decrease feed rate.
Note: Keep in mind the impact of other factors upon the tracer level.
|
* Note: The control measures listed are general and may or may not be the best recommendation for your unique system requirements. Always consult with your water treatment professional to determine proper corrective measures.
Conclusion
Effective water treatment is a critical part of the preventative maintenance program for any cooling tower system. When determining a new water treatment program and critical process parameters, partnering with an experienced solution provider is vital. A customized water treatment program from Chem-Aqua does more than protect cooling water systems. Tailored treatment solutions help maximize the life, efficiency, reliability, and safety of cooling water systems while keeping energy, water, and maintenance costs to a minimum.
To learn more about Chem-Aqua® and our superior line of programs, products, and services, visit www.chemaqua.com today.