GT ROTOR ASSESSMENT CORRECTION OF GEOMETRICAL UNBALANCING

摘要

During Gas Turbine rotor lifetime specific tests are performed to assure safe and efficient operations, aiming at savings in manufacturing and maintenance. By proposing new tools and processes, OEM pursue higher quality standards for new built rotors and try to reach the same quality level applied in factory also to field; their aim is also reducing operations time and costs. As a consequence the rotor assessment before/after the scheduled maintenance outages becomes more and more important. Some fundamental issues connected with the rotor dynamic assessment are the following : rotor shape diagnostic: including the whole measurements needed for detecting axial dissymmetries, which may cause rotor unbalances; mass distribution measurement in rotating stage, depending on the particular blades sequence in a set at first and/or at following assembly; radial homogeneity of blades tips, affecting the GT performances. In last years, Ansaldo Energia (AEN) has developed some special tools for measuring axialdissymmetries either on blade tips and on rotor components, in order to improve its own competency and speed on GT rotor assessment. In addition, a system has been set to support decisions about corrective actions to be performed on rotors, complying the highest quality standards. Presently, AEN is deepening the way to get high quality standard while reducing intervention duration by performing, before any action, an analysis suggesting the best and most suitable mix of possible corrective actions among bearing collar turning, blades assembly sequence optimization, balancing rotor weight, rotor disks rotation and so on.