Background
A large lake-cooled power station in New South Wales was having major problems with the cooling capacity of its main condensers. As a result, de-rating of the generators, particularly in the hot summer months, was not uncommon. This came at a significant financial cost to the owner, and of-course the wider electricity grid and energy consumers.
An inspection of the condenser tubes during an outage showed clear evidence of biofilm, caused by biological activity in the cooling water. Biofilm has a higher insulation factor than CaCO3, and was a major contributing factor to the lack of cooling capacity of the condensers.
The original design of the plant included a chlorine gas disinfection system, however this had been decommissioned for many years and no replacement disinfection system was ever implemented.
WTS had been supporting other aspects of the site’s water for years; we were subsequently tasked with finding the best solution to control the biofilm.
Approach
Realising that biological control had been lost, WTS explored many options to replace chlorine gas. We applied our four-phase solution process to make their cooling water work again.
Solution
The solution was chlorine dioxide (ClO2). Not only could ClO2 handle the elevated pH of the cooling water, it also had little effect on corrosion rates of the copper-based condenser tubes. Ultimately, it gave a superior penetration and clean-up of the biofilm and maintained cleanliness of the condenser tubes.
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WTS engineered & manufactured Chlorine Dioxide generator
Results and benefits
- Full power. Thanks to clean & fully effective condensers, the power station never de-rated their generators due to cooling problems again, even through a period of drought which reduced their cooling lake’s capacity.
- No additional corrosion. Testing showed ClO2 had negligible effect on the corrosion rate of the copper condenser tubes
- Biofilm eliminated. ClO2 is a strong biocide that kills, penetrates and cleans-up biological growths.
- ROI. Elimination of cooling-induced generator de-rating gave the power station a strong financial case to continue the WTS managed ClO2 generation and disinfection program.
- Safety. ClO2 is far safer than the original chlorine gas system that had been decommissioned years prior.
