Evaporative cooling systems such as cooling towers are widely used for rejecting heat and maintaining temperatures in a variety of applications by directing high flow rates of air counter-currently to water flow. This, consequently, also makes cooling towers excellent air scrubbers. Whether cooling towers are utilised to provide cooling for an industrial facility or simple air conditioning in a building, the water treatment program can make a key difference in their operation.
Besides corrosion inhibitors, biocides and bleed control, filtration is not commonly seen or usually viewed as a basic water treatment requirement for cooling towers. This is somewhat baffling considering that a simple 100 ton cooling tower can scrub the air contained in Toronto’s Skydome in only 24 hours! Yet, many cooling tower owners do not employ a filtration technology as part of their regular water treatment program despite the fact that when properly selected and sized, the use of a filtration system can result in trouble-free operation and significant savings in operating costs.
Filtration technologies are numerous and can range from manual replacement systems such as cartridge or bag filtration to more sophisticated automated systems employing sand, vortex, or other methods.
It goes without saying that the cooling tower water will be cleaner when filtered, but what does this mean in practical terms for the mechanical system? Here are 5 reasons why filtering cooling tower water makes sense:
1 – Decreased blockages and down-time
When the proper type of filtration is employed, particulate matter and suspended solids originating from the surrounding environment or from the system’s piping or process will be removed from the cooling tower water. This can mean decreased deposition in the hot water distribution basin, fill, and cold water sump of the cooling tower, as well as reduced blockages in heat exchangers, piping, or other critical process components. This, in turn, can mean improved operation of the system with less unscheduled down-time.
2 – Decreased energy use and maintenance costs
Savings in energy and maintenance can be significant with the installation of the right filtration technology. As mentioned in the previous point, cleaner water can mean decreased deposits, which in turn, can translate into greater heat transfer efficiency and lower energy usage. Furthermore, the frequency of periodic cleanings of system components can decrease, or the cleanings themselves may take much less time and be easier to perform, thus reducing maintenance costs.
3 – Increased effectiveness of corrosion inhibitor
Filtered cooling tower water may not only minimize under-deposit corrosion, but increase the effectiveness of the corrosion inhibitor that is utilised, since the absence of deposits will allow for a better passivation of the system metal, consequently prolonging the engineering life of the system. In addition, less suspended solids in the water can allow for a more efficient use of the inhibitor since it will bind mostly with the system metal and components rather than with the particulate matter.
4– Better Bacteriological Control
Similarly to the corrosion inhibitor, the water treatment program biocides and bio-dispersants will also benefit from an increased notch in effectiveness due to the fact that there are simply less nutrients and organic matter in the water for the bacteria to feed on and flourish. In turn, fewer quantities of these products may be required to maintain proper bacteriological control in the system resulting in chemical savings.
5 – Minimizing the Risk of Legionella Bacteria
Finally, in line with the previously stated reason, the risk of the presence of Legionella bacteria in the cooling tower water can also be minimized due to the increased effectiveness of the biocides and bio-dispersants. Furthermore, since most filtration systems come packaged with a circulation pump, stagnation and the presence of dead legs in the system piping can simultaneously be eliminated, thus further reducing the risk of the presence of these potentially problematic bacteria.
When properly selected and sized, filtration systems can be an invaluable part of a cooling tower water treatment program as they can greatly benefit the operation of a cooling tower in terms of its water quality, mechanical efficiency, and overall operating costs. Klenzoid representatives are available to discuss your site specific filtration needs.