Annual maintenance at power plant is moving along steadily
WILLMAR -- Employees at the Willmar Municipal Utilities power plant are doing a lot of heavy lifting these days.
They're changing and repairing gears, shafts and cast-iron boiler parts weighing hundreds of pounds during the annual spring maintenance project. It's all part of their effort to keep the lights burning in Willmar.
Most power plants including Willmar's have some annual maintenance and it's usually done in the spring or fall when the electrical load is down.
"We have annual maintenance so we maintain reliability through the rest of the year,'' says Ken Nash, power production superintendent.
"We keep a list of stuff that goes wrong during the year that we need to fix while it's down and not hot, and go after that when we're shut down.''
The boiler was shut down April 6 and should return to service in about two weeks. Meanwhile, personnel are working inside and around cooled machinery that normally operates under intense heat.
More maintenance than usual is being done this year on the shafts of unit No. 3, the main coal-fired boiler. Tom Leenstra, relief operator, said new front and rear shafts, new bearing mounts, new bearings and new front air seals were installed, and the grate tracking system was rebuilt.
Nash said the shafts had not been replaced since the boiler was new in 1959. "And it was in amazingly good condition,'' Nash said.
The shafts consist of two 15-foot pieces, each weighing about 800 pounds. The shafts go in from one end and must be aligned correctly to avoid binding or sticking in the bearings. The slowly rotating shafts drive the grate system that carries the coal dropped by the stokers. The stokers are disassembled and parts replaced as needed.
Much of the work proceeds slowly with the use of hoists and rigging. So far, only one finger has been pinched. The injury was treated and the crew member returned to work, said Nash.
"It's all manageable. It doesn't have to be a very big (piece) before it can be really heavy with cast iron,'' he said.
Nash said the work is going real well.
"We have a pretty talented maintenance crew here,'' he said. "We make sure there is nothing getting ready to happen to us that would shut us down. It's mostly checking everything over and replacing consumables.''
Of the 19 power plant employees, seven are working on maintenance. Some of the power plant employees work the night shift.
Utilities General Manager Bruce Gomm said this was a good time to have an outage.
"One of the concerns we always have when we shut our power plant down is the cost of the replacement power, and we have to buy that from the Midwest Independent System Operator, what is called local marginal pricing, which is basically the real-time pricing,'' he said.
Typically the cost of that power, at least during peak hours, is more than the cost of local generation, he said. The utility plans for higher power costs because annual maintenance is required.
But for a variety of reasons, that price has actually been running less than the cost of local generation.
"The cost of power and maintenance will be coming in under budget,'' Gomm said. "Part of the maintenance cost that we budget for is the replacement power. That will be coming in under what we expected it to be.''