Gas units undergoing combustor, hot section replacement

Basin Electric’s natural gas generation facilities are undergoing the replacement of two major components of the units’ turbines. The combustor and subsequent hot section (high pressure turbine, or HPT), the area of the turbine that reaches high temperatures (as high as 1,600 degrees Fahrenheit), are being replaced as part of an effort to maintain the fleet.

“After about 25,000 hours of use, the coating on the hot sections breaks down and high temperatures wear on the metal causing lower efficiency and the risk of a catastrophic failure,” said Jesse Folk, Basin Electric senior mechanical engineer. “If a unit experienced a catastrophic failure, we wouldn’t just need to replace the combustor and HPT but every section after that, so it’s in our best interest to replace these sections before that happens.”

Folk said some of these components will last beyond the 25,000-hour expectancy and some will fall a bit short, which is why it is imperative that the equipment is inspected on a biannual basis. If the equipment is showing signs of wear replacement is budgeted and scheduled.

Because groups of the natural gas units were constructed around the same time, they all are requiring this maintenance around the same time, as well. Folk said the combustor and hot section in Lonesome Creek Station Unit 1 was the first to be replaced in 2016.  Lonesome Creek Station Units 2 and 3 underwent the same maintenance in 2018 and 2019 respectively; and units at Pioneer Generation Station, Culbertson Generation Station, and Groton Generation Station followed. Lonesome Creek Station Units 4 and 5 will be the final facilities to receive the new equipment, scheduled in 2022 and 2023. These projects are scheduled to be conducted during regular maintenance outages in the spring and fall.