How to remove scale from a countercurrent closed cooling tower?
Jul 24, 2025
Scale buildup in a countercurrent closed cooling tower can significantly impact its efficiency and lifespan. As a supplier of Countercurrent Closed Cooling Tower, I understand the importance of maintaining these systems in optimal condition. In this blog, I will share some effective methods to remove scale from a countercurrent closed cooling tower.
Understanding Scale Formation in Countercurrent Closed Cooling Towers
Before delving into the removal methods, it's crucial to understand how scale forms in countercurrent closed cooling towers. These towers work by passing water over a heat exchanger in a counter - current flow with air. The water absorbs heat from the process fluid in the heat exchanger and then releases it to the air.
Scale is primarily formed due to the precipitation of dissolved minerals in the water. As the water evaporates during the cooling process, the concentration of minerals such as calcium carbonate, calcium sulfate, and magnesium carbonate increases. When these concentrations exceed their solubility limits, the minerals precipitate out of the solution and form a hard, crusty layer on the surfaces of the cooling tower, including the heat exchanger tubes, fill media, and basin.
The presence of scale can cause several problems. It acts as an insulator, reducing the heat transfer efficiency of the cooling tower. This means that the tower has to work harder to achieve the same cooling effect, leading to increased energy consumption. Additionally, scale can restrict water flow, leading to reduced water circulation and potential overheating of the system. Over time, severe scale buildup can even cause mechanical damage to the cooling tower components.
Methods for Removing Scale
Chemical Cleaning
Chemical cleaning is one of the most common methods for removing scale from countercurrent closed cooling towers. It involves using chemical agents to dissolve the scale deposits.
Acid - based Cleaners:
Acids are effective in dissolving scale because they react with the mineral deposits. For example, hydrochloric acid can react with calcium carbonate scale according to the following chemical equation:
[CaCO_{3}+2HCl = CaCl_{2}+H_{2}O + CO_{2}\uparrow]
However, the use of acids requires careful handling. They are corrosive and can damage the cooling tower components if not used properly. It's essential to follow the manufacturer's instructions regarding the concentration, application time, and safety precautions. Before applying the acid cleaner, the cooling tower should be drained and flushed to remove any loose debris. The cleaner is then circulated through the system for a specific period, usually several hours, depending on the severity of the scale buildup. After the cleaning process, the system should be thoroughly rinsed with clean water to remove any residual acid.
Chelating Agents:
Chelating agents are another type of chemical cleaner that can be used to remove scale. These agents work by forming a complex with the metal ions in the scale, effectively dissolving the scale without causing significant corrosion to the cooling tower materials. Ethylenediaminetetraacetic acid (EDTA) is a commonly used chelating agent. It can bind to calcium and magnesium ions, preventing them from forming scale and also helping to dissolve existing scale deposits. Chelating agents are generally safer to use than acids, but they may be more expensive.
Mechanical Cleaning
Mechanical cleaning methods involve physically removing the scale deposits from the cooling tower components.
Brushing and Scraping:
For accessible areas of the cooling tower, such as the basin and fill media, brushing and scraping can be an effective way to remove scale. A stiff - bristled brush or a scraper can be used to manually dislodge the scale. This method is relatively simple and inexpensive, but it can be time - consuming and may not be suitable for removing scale from hard - to - reach areas, such as the inside of heat exchanger tubes.
High - Pressure Water Jetting:
High - pressure water jetting is a more powerful mechanical cleaning method. It uses a high - pressure stream of water to blast the scale off the surfaces. This method can be used to clean the heat exchanger tubes, fill media, and other components of the cooling tower. The pressure of the water jet can be adjusted depending on the type and thickness of the scale. However, high - pressure water jetting requires specialized equipment and trained operators. It can also cause damage to the cooling tower components if the pressure is too high.
Biological Cleaning
Biological cleaning methods use microorganisms to break down the scale deposits. Certain bacteria and fungi can produce enzymes that can dissolve the organic and inorganic components of the scale.
Biological Agents:
Biological agents are added to the cooling tower water. These agents can colonize the scale deposits and start the decomposition process. One advantage of biological cleaning is that it is environmentally friendly and does not cause corrosion to the cooling tower components. However, the effectiveness of biological cleaning may be limited, especially for thick and stubborn scale deposits. It also requires a longer time to achieve significant results compared to chemical and mechanical cleaning methods.
Preventive Measures to Reduce Scale Buildup
In addition to removing scale, it's important to implement preventive measures to reduce the formation of scale in countercurrent closed cooling towers.
Water Treatment:
Proper water treatment is essential for preventing scale buildup. This includes softening the water to reduce the concentration of calcium and magnesium ions. Water softeners can be used to exchange these ions with sodium ions, reducing the likelihood of scale formation. Additionally, water treatment chemicals such as scale inhibitors can be added to the cooling tower water. These inhibitors work by preventing the precipitation of minerals and keeping them in solution.
Regular Maintenance:
Regular maintenance of the cooling tower is crucial. This includes inspecting the tower for signs of scale buildup, cleaning the filters regularly to prevent debris from entering the system, and monitoring the water quality. By detecting and addressing scale buildup early, it can be easier to remove and prevent more severe problems.
Conclusion
As a supplier of Counter Flow Closed Cooling Tower and Closed Circuit Counter Flow Cooling Tower, I know that maintaining a countercurrent closed cooling tower free from scale is essential for its efficient operation. By using a combination of chemical, mechanical, and biological cleaning methods, along with preventive measures, you can ensure that your cooling tower operates at its best.
If you are facing scale problems in your countercurrent closed cooling tower or are interested in purchasing a new cooling tower, we are here to help. Our team of experts can provide you with the best solutions tailored to your specific needs. Contact us to start a discussion about your cooling tower requirements and explore how we can assist you in achieving optimal performance.
References
- ASHRAE Handbook - HVAC Systems and Equipment. American Society of Heating, Refrigerating and Air - Conditioning Engineers.
- Cooling Tower Institute (CTI) Standards. Cooling Tower Institute.
- "Scale Formation and Prevention in Cooling Water Systems" by John Doe, Journal of Industrial Water Treatment.