Cooling towers can accumulate a colossal 275 kilograms of suspended matter in a single year if left untreated. This can lead to a range of issues that can negatively impact everything from efficiency to productivity, says Simona Vasilescu of NCH Europe .
9 February 2017 | Simona Vasilescu
Cooling towers can harbour conditions favourable to pathogens, such as Legionella, so an adequate water treatment regime is essential to protect employees and people living nearby. Water treatment negligence can also lead to unnecessary electricity use. Here are five areas to consider when ensuring compliance.
1. Identify the two types of cooling tower
Industrial evaporative condensers and draft cooling towers are easily confused, but there is a key difference between them. In draft cooling towers, the air outside of the tower is used to cool the water inside through an air inlet. In evaporative condensers, gas contained in a tube is cooled by a heat transfer process that requires water to flow over it, creating condensation.
2. Keep contaminants clear
Draft cooling towers are, in essence, massive air scrubbers, so the most problematic issues will arise from external contaminants entering the water supply. In such a large structure reliant on external cooling it is impossible to stop particles such as pollen or silt being drawn into the system. Once these insoluble particles are in, they form deposits on surfaces. This is known as fouling.
3. Dealing with silt
Don't confuse fouling with scaling. Both result in deposits forming on equipment, but there is a distinct difference between the two, and each requires a different water treatment solution. Silt in your system won't dissolve and will eventually form a sludge that will clog up your system and promote microbiological fouling. Scaling occurs when calcium ions exist in a body of water where carbonate is also present, the result of which is the formation of crystals on pipes, which will continue to grow until they are treated and removed, all the while affecting productivity and incurring financial expense.
4. Sulphate-reducing bacteria can cause problems, too
Evaporative condensers face similar issues, but the impact is different. For example, if sulphate-reducing bacteria made their way into the water supply during a process of contamination in this type of cooling tower the effect on production would be felt very quickly. As water flows over iron pipes bacteria can easily latch onto the surface and form sulphide salt deposits. These deposits accelerate corrosion, leading to the system falling victim to microbiologically induced corrosion.
5. Sample the water
There's no secret when it comes to water treatment to stopping harmful contaminant build-ups - it's all in the chemistry. Understanding the cooling tower you're using and identifying the problems ahead means you're already halfway to solving them as you will be able to identify the correct dosage of the most appropriate chemicals, like inhibitors and biocides.
Regular sampling and testing of the water circulating your cooling tower helps us keep you ahead of potential problems. Keeping everything clean, safe and functioning properly requires eternal vigilance.