Turbine Remanufacture - One Option For Reliability And Efficiency Improvement.

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Johns, David A.; Rasmussen, David; Beverly, James
Texas A&M University. Turbomachinery Laboratories
artifact description
A case study of a remanufacture of a steam turbine is presented. The turbine has been in service for 20 years. Thermal and physical stresses have taken their toll on the turbine casing and supporting hardware. Remanufacture was planned with innovative processes and state-of-the-art component upgrades. A unique heat treatment process was designed to reshape the casing and relieve residual stresses thermally induced into the casing over its operating life. Using heat to reshape the case minimized the amount of remachining time required. A team of three vendors was combined to maximize technical and physical resources and accomplish this task in 24 days. The goals of the remanufacture included: • Recovery of lost horsepower and efficiency due to steam path deterioration • Increase efficiency through the application of packing, tip, and nozzle seal upgrades • Elimination of chronic maintenance problems. Major topics include: • Casing disassembly and damage assessment • Weld restoration of erosion damage and steam path blading • Distortion modelling and evaluation • Heat treatment of case • Assessment of heat treatment results • Machining steps required • Design and installation of retractable packing • Design and installation of tip seals and nozzle seals • Successful startup and operational history