The author Thomas Charlton was the first person to use the often misattributed phrase, "the price of liberty is eternal vigilance." Perhaps if he had he worked in the water treatment industry, he would have said, “the price of production is eternal vigilance.” Cooling towers are the perfect embodiment of this notion as they can accumulate a colossal 275kg 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, explains Simona Vasilescu, marketing manager of NCH’s Water Treatment Innovation Platform.
Safety is of the utmost importance as cooling towers can harbour conditions favourable to pathogens, such as Legionella. Consequently, an adequate water treatment regime is essential for the protection of employees and members of the public who live nearby. Water treatment negligence can also lead to excessive and unnecessary electricity use.
The first step to combating issues that regularly arise in cooling towers is identifying the type of tower you have. Industrial evaporative condensers and draft cooling towers are easily confused, but there is a distinct difference between the two. In draft cooling towers, as the name suggests, 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.
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 prevent particles such as pollen or silt being drawn into the system. Once these insoluble particles are in, they settle and form deposits on surfaces. This is known as fouling.
It’s important not to confuse fouling with scaling. While both result in deposits forming on equipment, 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, however, occurs when calcium ions exist in a body of water where carbonate is also present. The end 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.
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 begin to form sulphide salt deposits. These deposits accelerate corrosion, leading to the system falling victim to microbiologically induced corrosion.
There’s no magic formula or secret when it comes to water treatment to prevent harmful contaminant build up, it’s all in the chemistry. Understanding the cooling tower you’re using and identifying the problems ahead means you’re already half way to solving them as you will be able to identify the correct dosage of the most appropriate chemicals, like inhibitors and biocides.
That’s where working with a company like NCH comes in handy. Not only are our water treatment solutions completely bespoke for the unique requirements of individual systems, we’re constantly on hand to support ongoing monitoring and maintenance. 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 constant surveillance and eternal vigilance. You might say it seems like a pipedream. As painful as that pun may be, it’s only half as painful as the downtime and costs you’ll encounter if you neglect water treatment.