Retrofittable casings enhance 7B turbine performance
A GE Gas Power customer, a major natural gas power station in south Texas, had experienced turbine and exhaust casing cracks, as well as out of roundness issues. The customer experienced downtime and costly repairs from out of roundness issues in its peaking operation, with 100 to 200 starts per year. Operators observed cracking, which initiated and propagated. Despite appropriate maintenance—drill relief holes to stop propagation—the cracks continued.
The costs related to downtime and operational maintenance were mounting, without resolving the issue. In response to these concerns, which are driven by cyclic duty heat cycles and age, the customer had upgraded a 7B with a 7E turbine end.
More recently, after a competitive search for the best solution, GE products were selected to replace the exhaust frame assembly (casing plus diffuser) on two units with 7EA configuration exhaust frame assemblies, as well as replace the turbine shell on one of those units. The unit with turbine shell replacement recovered an additional 3-4 MW when compared to the sister unit.