The bacterial count is way down while uptime is right up
Danfoss has achieved cleaner cooling water, fewer production shutdowns, and lower costs on several fronts, after Danish Clean Water’s units were installed on the cooling towers that serve the production areas.
The engineering company Danfoss previously combatted bacteria in its production cooling systems with the use of strong chlorine products several times a week. However, for more than ten years, Danfoss has had units from Danish Clean Water (DCW) installed on six cooling towers in Denmark to ensure continuous cooling of the machinery with no unplanned downtime.
“None of us worry about the bacterial count or the like in the coolers today, but before we started using this solution, it could be several thousand per millilitre. That figure is now one or two bacteria per millilitre at most, so the cooling water is actually cleaner than drinking water. The vessels are biofilm-free, and we never experience production shutdowns due to the formation of biofilm. If we prevent just one shutdown on a machine in a year, the costs of this solution are amply recouped,” says Martin Brander, Senior Manager for Global Section Integration at Danfoss.
Cooling tower serving the Danfoss production areas.
Combating algae and biofilm
The collaboration began with the mirror pool in the entrance of Danfoss’ headquarters, where the company had fought a tough, chemical-based battle with algae for many years. The battle for an algae-free pool was not won until Danfoss tried a DCW unit, which quickly solved the problem and at the same time saved the company DKK 100,000 a year on chemicals. It occurred to Martin Brander that this method could also benefit Danfoss’ production process.
“Spurred on by the success with the mirror pool, we wanted to test the same technology and method on our cooling system in the production areas, where production shutdowns happened regularly because the exchangers were clogged by algae and biofilm. Machine downtime was costing us a lot of money and happening too often,” he says.
A solution using just water, salt and electricity
The secret behind the DCW solution is hypochlorous acid (HOCl), produced by electrolysis using water, salt and electricity. Hypochlorous acid is the active ingredient in the disinfectant Neuthox, which the DCW units dose into, among other things, the cooling water in an ultra-low and very precise concentration. Neuthox effectively destroys bacteria, and at the same time it is safe for humans and the environment.
“We no longer have bacteria and other build-up circulating in the pipes, and this saves us on repairs and maintenance on our cooling towers. It also reduces electricity consumption, as the cooling water pumps can get the water around more easily. All we have to do now is to refill the units with salt and check them twice a year. Otherwise, they run efficiently and stably. The constant uptime is crucial to us,” says Martin Brander.
Martin Brander also emphasizes that the solution provides a safer working environment: “We no longer have to deal with chemicals in the cooling towers, and at the same time there is no risk of spreading Legionella bacteria in the air, because the cooling water is completely clean. Legionella can otherwise grow in the biofilm in vessels and pipes and atomize itself to the surroundings when the cooling water evaporates,” he says.
Facts
Danfoss previously experienced high bacterial counts of 30,000 CFU/ml in 37-degree cooling water. When the DCW units were installed 10+ years ago, the bacterial counts dropped to practically none and have remained at that level ever since.
The DCW units dose Neuthox into, among other things, the cooling water at Danfoss, so the cooling towers are kept clean.
Key benefits of the DCW solution
- Effectively removes bacteria, biofilm and algae
- Prevents downtime and ensures stable operation
- Saves time and money on repairs and maintenance
- Cuts chemical purchases, transport and CO₂
- Improves safety by replacing dangerous chemicals
- Reduces the risk of spreading Legionella in the air
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