Overhaul keeps Willmar, Minn., power plant steam turbine spinning
WILLMAR - A once-every-five-year overhaul project finds the steam turbine that produces some of Willmar's electricity at the 65-year-old city power plant is in good condition.
"The good news is that the turbine is in very good condition, especially considering its age,'' says Jon Folkedahl, supervisor of power production for Willmar Municipal Utilities. "We have to inspect it and rework it every five years. But like I keep telling people, we have to continually rebuild something at the power plant because of its age.''
Folkedahl said insurance companies require the utility to overhaul and inspect the steam turbine every five years and this year happens to be the fifth year in the cycle.
Work began after the power plant was shut down April 1, but the job has taken longer because some things were found in the steam turbine that required lengthy repairs. Folkedahl said three of the main bearings needed to be shipped to vendors who were backed up.
Folkedahl said everything was rebuilt that needed rebuilding, and he hoped the turbine would return to service today or Friday.
"It took quite a while to get those main bearings back. But in general the turbine is in very good shape, as is the boiler,'' he said.
The boiler was also out of service for normal annual maintenance. Utility workers crawl through the entire boiler, make repairs and bring in outside consultants to make visual inspections.
"We repair the little things that have gone wrong over the years,'' said Folkedahl.
The boiler sends steam made from water to the turbine, which is like a giant pinwheel. Steam spins the turbine, which turns the electric generator, which sends electrical energy throughout the town.
Work on the steam turbine requires specialists.
"Normally, we don't take apart the steam turbine. It's specialized work. It's extremely close tolerances that must be observed. So we have to bring in specialized craftsmen to do that kind of work,'' said Folkedahl.
Local generation is part of Willmar's energy portfolio, providing 14.2 percent of the city's electrical load in 2012, said Chris Carlson, power supply broker. Carlson said the energy that would have been provided by the turbine during the maintenance project was replaced with power purchased under current contracts and on the open market.
Folkedahl said the cost of repairing the main bearings and a few other items pushed the cost about 10 percent over budget, "but it was all reasonable.''