Hydrolox Screens: Five Years, Zero Unplanned Maintenance

Through its subsidiaries, Xcel Energy produces power for millions of customers across the Western and Midwestern United States. Its Wilmarth Generating Station in Mankato, Minnesota, is an 18-megawatt, two-unit generating plant that burns refuse-derived fuel. The plant had been using two traditional, chain-driven steel screens measuring 10 ft x 45 ft (3.05 m x 13.72 m) to protect its cooling water intake condensers from debris. The screens, situated inside an enclosed screen house, required constant maintenance and broke down often despite being run only intermittently. They also failed to prevent high amounts of leafy debris from clogging the condensers, which hindered efficiency and power production.

Xcel Energy wanted a new, more durable screening solution that would operate 24/7 year round, reduce maintenance costs, enhance debris removal, and improve output and performance. The power plant chose to replace its steel screens with two Hydrolox Series 6000 traveling water screens with debrishandling flights. Because the screen house offered no roof access, the Hydrolox team worked with Xcel Energy to specially design the screens in sections so that they would fit through a door.

Since installing the screens in 2013, Wilmarth Station has enjoyed dramatic increases in reliability, efficiency, and performance. Rotating 24/7 year round, the screens have generated zero additional or unexpected maintenance, and the condensers require half as much cleaning and maintenance as before. The plant’s overall power production has improved significantly. Xcel Energy was also pleased that the screens could later be quickly and easily converted (using Ristroph-style buckets) to comply with Section 316(b) of the EPA’s Clean Water Act. The company plans to implement Hydrolox solutions at other affected plants across the USA.