A Method for Minimizing the Tightening Force Variation in a Single Center Tied Rotor that Occurs during Operation of a Large Gas Turbine

Abstract

EthosEnergy has developed a rotor solutions program to introduce to the marketplace. Integrity of rotor assembly is very critical for safe and reliable operation of a gas turbine. Rotor components have finite design life and consequently, planned maintenance involving inspection and replacement of life limiting components is critical for reliable operation. Rotor reliability issues can cause unit unavailability, increased maintenance costs and forced outages. Recently, OEM has released a technical information letter (TIL) to inform customers of end of life of rotor and consequence of rotor failure, if prescribed maintenances are not performed. To address rotor end of life issues, some independent service providers may offer inspections during a planned maintenance and rotor life time extension. Rotor life time interval extension needs to be based on engineering assessment of operating stresses/temperature, understanding of material failure modes, advanced NDE inspection techniques, OEM know-how, etc., which many of these independent service providers may not have. As a result, fidelity of a life time extension recommendation provided by an independent service provider should be carefully evaluated relative to risk associated with consequence of a rotor failure. Contrary to many other service providers including OEM, EthosEnergy has adopted a different approach by offering a cost-effective rotor solution. Using state-of-the-art engineering tools and advanced manufacturing techniques, EthosEnergy has designed replacement compressor and turbine wheels for frame 6 and frame 7 gas turbines. EthosEnergy wheels are interchangeable with OEM components and can be tailored to accept in-kind or improved blade root profile. EthosEnergy solution is to replace life limiting components of a rotor and thereby minimize overall project cost for a typical user. EthosEnergy rotor exchange program has been developed to reduce our customers risk profile at a cost substantially below a complete replacement of an OEM rotor. Details of EthosEnergy rotor solution will be discussed in this paper.