Emergency Damage Restoration Experiences of 25MW Heavy-Duty Gas Turbine: Bearing Retrofit Design and Test Run

Abstract

Case Study 6: A 25MW gas turbine had been damaged during operation. Particularly, its tilting pad journal bearings and shaft journals had suffered complete wiping‐out and deep crack damages, respectively. For an emergency restoration, both cracked journals had been machined out as much as 2% per the specified design diameter, and a series of design, analysis and manufacturing of the retrofit journal bearings had been carried out to have practically identical overall design characteristics to the OEM bearings. To verify operational reliability, the restored GT rotor had been test‐run at KIMM's high‐speed balancing facility. Since the test results had been favorable, the rotor had been put into an onsite operation, immediately. The restored GT system has been continuously running a stable commercial operation for more than 41 months up until now. This presentation introduces design analysis of the retrofit bearings, test run result of the restored GT rotor‐bearing system, and the lessons learned.