Tri-State Generation & Transmission Assn. expects the coal-fired Craig Unit 1, which went down on Sept. 7 due to equipment issues, to be back in operation in mid-December.
Meanwhile, the Colorado-based cooperative said in an Oct. 31 blog posting that employees are making the most out of the difficult situation that occurred on Sept. 7 when a water induction event on the plant’s Unit 1 turbine/generator caused significant damage resulting in an unscheduled outage.
“We’ve moved up our planned 2014 minor spring outage to right now to take advantage of the downtime while the turbine is being repaired to complete a fairly long list of maintenance and capital projects that we had planned for next year,” explained Rick Johnson, the Craig Station’s plant manager. “With the repairs that we are doing on the turbine, coupled with our rescheduled routine outage activities, we should be well positioned to reliably operate Unit 1 until its next scheduled major outage in 2016.”
Another potential silver lining to the unfortunate outage event was the discovery of a ground fault during a diagnostics check on the Unit 1 generator field that, if not corrected, could have caused a costly and lengthy electrical failure on the unit, said engineering superintendent Dana Gregory. The corrective measure – a generator field rewind – will also be accomplished within the projected turbine repair timeframe.
“Normally, we plan at least six months to a year ahead of time for an outage,” said Lisa McCurdy, maintenance planner and scheduler. “But, we have had a lot of support from our people here at the plant and at headquarters to help us get the materials and people that we need to accomplish this work while the unit is offline.”
Work on the Craig Unit 1 turbine is mainly focused on rebuilding the high pressure / intermediate pressure steam path components and the generator field rewind. These repairs will be completed by General Electric. Craig personnel will handle turbine valve repairs on the unit.
In the meantime, the rescheduled spring outage is in full swing at the plant, with a long list of inspections and maintenance activities, as well as several capital projects in progress throughout the Unit 1 portion of the plant.
“We have a lot of work going on in our unit one boiler, where we are making repairs and inspections to our water wall and re-heat tubes,” McCurdy said.
Other activities include numerous inspections and repairs of values, pumps and fans, air heaters, motors and many other plant components and systems that are vital to round-the-clock operation of the units.
There are three capital projects underway at the plant during the outage. They are improvements to the fire suppression system on Unit 1’s coal feeder and mills, a generation protection upgrade and a partial refurbishment to the Unit 1 cooling tower.
Craig provides the association with a total of 655 MW of relatively low-cost, reliable generation. Operated by Tri-State, this is a three-unit, 1,311-MW plant. Craig Units 1 and 2 make up the Yampa Project, owned by Tri-State and four other regional utilities. Tri-State is the sole owner of Unit 3.