Frame 5 Rotor Reconditioning and Rotor Life Assessment

Most large pulp and paper mills require vast amounts of reliable, base-load electric power. They also depend on steady high-temperature air and steam for their process operations.

A large mill anticipated its current General Electric® Frame 5 gas turbine’s rotor would reach the end of its life cycle in 2024. A replacement would be needed. The responsible, forward-looking solution was to locate a spare rotor and have it immediately available for the upcoming outage. Having reliable spare equipment on site would lessen the disruption.

Research led the owners to a used GE® Frame 5 gas turbine rotor which had the potential to be refurbished and its lifespan extended, then held in controlled storage until the changeout.

The mill owners also knew who to call for the reconditioning and rotor life assessment – the turbine-generator experts at Mechanical Dynamics & Analysis.

The spare was obtained and shipped to MD&A’s full-service turbine-generator repair facility in St. Louis, Missouri to institute their proven gas turbine rotor life assessment program and recondition this critical piece of equipment.

Traditional rotor evaluations at MD&A feature advanced NDE results and metallurgical evaluations, engineering analyses, and any required stress and thermal modeling.

Upon arrival, the asset was immediately inspected and analyzed based on its past operations, as-found status, and forecasted activity and service life requirements.

Exacting measurements were taken of all journal diameters and internal axial distances. Complete incoming runouts were performed, as well as compressor blade drops.

Individual section runout measurements and balance data were taken for all stages. Bore hole and rabbet details were included, all to be checked again after the final assembly.

Dummy journal, distance piece, and turbine wheel runouts were also performed, and compressor wheel interference fits were analyzed.

Blade inspection and replacement blade installation on the compressor followed, featuring proprietary coatings.

Re-stacking  

The rotor was then prepared for the MD&A Gas Turbine rotor stacking elevator in St. Louis, carefully aligned and verified according to the MD&A stacking program.

Stack processes and procedures were carefully monitored and controlled.

Each step included a stone face procedure to remove any high metal after cleaning, followed by compressor assembly coupling bolt stretch and thermal gap analysis.

Finishing journal diameters were taken, followed by thrust runner and coupling face measurements.

Additionally approved by the customer in the compressor section, MD&A experts performed concluding and comprehensive runouts, then recorded and evaluated.

Experts also machined the R0 journal and thrust faces after assembly, and machined selected forward fits. For the turbine section, they also machined the T2 journal after assembly, selected fits and radii to corporate specifications, and interference corrections.

Balance and delivery

Final balance was performed at MD&A’s state-of-the-art high speed balance facility also in St. Louis.

high speed balance

MD&A’s comprehensive finishing inspections included but were not limited to the following:

• All blades free of marks and all blade damage properly addressed.
• Optimum condition of all journals.
• Speed gear properly installed.
• Balance weights staked and properly stamped.
• Verified completion of all non-conformance reports.

The Frame 5 rotor was then protected and prepared for transport.

Additionally, the remaining scope will be carried out during the outage:

• Tip grinding of the new compressor blades for optimum clearance and performance.
• Final machining of the turbine rotor rabbet fit to mate up the generator.

MD&A’s Gas Turbine Reconditioning and Rotor Life Assessment & Extension program is the ideal solution for any aging component. The focus on analysis, precision and perfection ensures the customer of reliable and predictable long-term operation.

MD&A can provide new, replacement wheels & discs for GE® 7FA and 7EA gas turbines.

Rely on the talented and experienced team at MD&A, backed by its world-class organization.

Talk to MD&A today to verify, recondition, and extend the life of all critical life-limiting assets.  Call (518) 399-3616 or use our Contact Form.