Background
The network, comprising a total of 1,050 kilometers of piping, dates back to 1965, making it one of the oldest in Sweden.
Several studies have concluded that the best way to eliminate corrosion issues would be to phase out the chambers where these problems and risks are most severe. However, due to high maintenance costs, the financial resources for this are lacking. "It's a Catch-22. The money we would have needed to phase out the chambers has been consumed by maintaining them," Mats explains.
Since March 2016, the district heating chambers have been protected by warm-condensation dehumidifiers, which have reduced moisture levels in the air and halted the corrosion process. "The critical threshold for corrosion is 60% relative humidity. Keeping the spaces below that level halts the corrosion process," explains Fredrik Edström, Head of Research and Development at Airwatergreen.
What problems did Airwatergreen's dehumidifiers solve?
Kraftringen and Airwatergreen developed the "Dry Climate" service.
This entails Kraftringen transferring responsibility for the climate within the chambers to Airwatergreen for a fixed monthly cost: "This means we don't have to tie up any capital. We receive a quarterly invoice and Airwatergreen handles the rest. In addition to lowering the humidity, Airwatergreen provides us with data on the condition of the chambers, which simplifies maintenance planning," Mats says. He also emphasizes that personnel operating within the chambers benefit from an improved working environment: "We want to offer a safe workplace."