Why Is There Foam in My Cooling Water?

Cooling water plays a vital role in transferring heat away from Foaming in cooling water can occur rapidly without obvious cause and is not always predictable by routine system monitoring.

A small amount of foam in cooling water can be normal due to the design of evaporative cooling systems. However, in extreme cases, foam can exit an evaporative cooling system and be blown into the air and around the facility. This makes it visible to the surrounding population. Without proper understanding of the causes or remedies, flying foam can alarm the general population.

Understanding Foam

Foam formation requires the presence of a surfactant (surface active agent) to lower air-water interface surface tension. Movement such as turbulence is required to mix air into the water.

Foam can be white or take on the color of contaminants present in the cooling water. It can be light and frothy, or thick like a slurry. These observations can be helpful when troubleshooting the source.

Factors Causing Foam

There are many reasons foam can occur, either temporarily or as a long-term phenomenon. Each factor can compound the effect of the other. Your water treatment supplier should help you take a comprehensive approach. Consider all the following:

1. Excessively High Alkalinity Total Dissolved Solids (TDS) of recirculating cooling water is controlled by bleed-off of system water. High TDS can mean extremely high alkalinity levels. This lowers the surface tension of the water and can lead to foaming. In some cases, well-controlled dosing of acid can be used as an alkalinity neutralizer,
2. Chemical Overfeed Maintaining. Water quality control parameters within recommended limits are important. This is not only for economic reasons, but also to lower the risk of causing foam by avoiding excessive chemical concentrations.
3. Increased Bacteriological Activity Foam. This can often be a result of inadequate bacteriological control. Your water treatment supplier can advise on the best biocide to use and method of feed and control. The proper use of a biodispersant is key to keeping wetted components clean and free of biofouling.
4. Reduction of Biological Activity. Foam can also be an indication that your bacteriological control is working! Once a bacteriological control issue is identified, correcting this with the use of a proper program can lead to foaming. This is usually a temporary situation which improves as the system becomes cleaner. Use of biodispersants can cause significant foaming until biofilm is removed, and good microbiological control is reestablished.
5. Process Contamination Cooling. Water can become contaminated, especially via leaking heat exchangers in manufacturing facilities. Oil leaks can be another cause of foaming. A new foaming situation in these applications can be a useful tool pointing to failure of heat exchange equipment.
6. High Degree of Suspended Solids Suspended. Solids are typically a result of scrubbing airborne contaminants into the cooling system by direct water to outdoor air contact. It can be removed with a properly sized filtration system.
7. Change in System Dynamics Modifying. Anything in the cooling system, such as increasing flow rates, adding new production lines, or tying in used equipment with questionable past treatment, can result in deposits becoming dislodged and contribute to This issue can be resolved by identifying and addressing the root cause.

Remedies

It is wise to always have industrial defoamer onsite as a short-term response to a foaming situation. Usually, very little defoamer is required to break the bubbles and release the air.

The following tips can help ensure foaming is not a cause for alarm at your facility.

1. Ensure that all water quality control parameters are consistently within control limits.
2. Consider upgrading control equipment and filtration for improved stability.
3. Perform regular inspections and tests of heat exchange equipment.
4. Perform pre-cleaning of any new sections added to the cooling system.
5. Monitor the effect of each improvement and fine-tune the program accordingly.
6. Add small amounts of industrial defoamer as a short-term urgent response tool as needed.

Conclusion

Due to the design of evaporative cooling systems, a small amount of foam can be normal. However, it’s important to stay aware of how much foam is in your cooling water and how to remove it.

Prevent foam in your cooling water by understanding the common causes and factors that create it. Doing this will increase the efficiency of your operations.