Cologne, 13 June 2012

Transcription

1 Power Gen Europe Track 6 Session 3: Maintenance Tools Paper ID # 323 GT ROTOR ASSESSMENT & CORRECTION OF GEOMETRICAL UNBALANCING AND BLADE TIP NON HOMOGENEUS SURFACE Cologne, 13 June 2012

2 Paper ID 323 GT ROTOR ASSESSMENT & CORRECTION OF GEOMETRICAL UNBALANCING AND BLADE TIP NONHOMOGENEUS SURFACE Authors: A.Rava (AEN), R.Traverso (AEN), A.Pesatori (PoliMI), M.Pastorino (UniGE) Co Author & Speaker: E.Pignone (AEN) 2

3 Agenda 1. Introduction 2. Present special tools for measuring axial dissymmetry 3. The way forward: OPAR evolution 4. Usage case study special tools for blade length special tools for radial run out 5. Future developments Face run out detection on Hirth teeth coupling Multi parametric methodology for GT assembly optimization 3

4 1 Introduction This work concerns some fundamental issues connected with rotor assessment and related maintenance tools. In particular: radial homogeneity of blades tips, which affects the Gas Turbine (GT) performances; rotor shape, regarding all measures for detecting axial dissymmetries, causing rotor unbalances; The aim is to reach the same quality level applied in factory also in the field. Lathe machine 4

5 1 Introduction Introduction to radial run out: The radial run out is the measure of rotor dissymmetry (eccentricity, ellipsoidality) in amplitude and phase, taken long the rotation axis measurements (depending on rotor size) in different axial sections Eccentricity measurements Vs axial position carries important information about rotor shape dissimmetries There is a correlation between rotor shape ad rotor balancing Introduction to blade tip radial homogeneity assessment: Blade tip non homogeneous radial length affects the Gas Turbine (GT) performances 5

6 2 Present special tools for measuring axial dissymmetry Among the special tools developed in the past by AEN, we can mention: BMS A real time contact less measurement system for the evaluation of the blade lengths, in order to avoid unacceptable radial inhomogeneities (BMS Blade Measurement System patent WO 99/45339). OPAR A system for measuring axial dissymmetries on rotorcomponents(rotorradialrun out), which can be applied both in the workshop and in the power plant (ROS radial Run Out Sensor Italian Patent 677/11). ROS 6

7 3 The way forward in AEN: OPAR evolution Presently, AEN is developing a new tool to check the axial dissymmetry of the rotor disk faces, along the Hirth coupling, which is used to connect two rotor disks together and is characterized by teeth bedding the end faces of each disk. F 1 (R 1,t ) α(t) Rd(t) Face run out α ο F 2 (R 2,t ) Radial run out 7

8 Usage case study BMS Measurements requirements : Relatively quick measurement Real time measurement during grinding process Different shape and material blades measurement Measurement accuracy of 20 μm High repeatability Allowing measurement while turbine rotating at 10 round/min 8

9 4 Usage case study BMS Measurement technique choice Time of flight: low performance (mm resolution) Interferometer: not suited for measurement of reflective target and not absolute measurement Optical barrier: low range of measurement, but high accuracy (micrometers) and suited for almost every measurement 9

10 4 Usage case study BMS System block diagram Emitter Optical beam Blades Mechanical positioner Worker Custom electronics Receiver 10

11 4 Usage case study BMS System transfer function and error x 11

12 4 Usage case study BMS BMS system in operation tuning of laser beam alignment 12

13 4 Usage case study BMS BMS system in operation blade length measurement Repeatability of 5 μm Accuracy of 10 μm over a range of 500 μm 13

14 4 Usage case study ROS Measurements requirements : Measurement accuracy of 2 μm High repeatability Allowing measurement while turbine rotating at round/min 14

15 4 Usage case study ROS Radial measurement sensor Measurement technique choice LVDT laser triangulator 15

16 4 Usage case study ROS Measurement technique choice in Operation&maintenance application Proxymity alerts Tilting control sensor Pitching sensor 16

17 4 Usage case study ROS Radial run out correction techniques After a first measurement phase, a system to support decisions about actions in order to correct the axial dissymmetry measured on rotors, can be applied. Such corrective actions are : 1. Bearing area turning machining, choosing one side only, i.e. turbine side or compressor side, or both 2. balancing weights introduction, 3. rotors unstacking with rotation of a part of rotor disks, choosing which parts have to be rotated to obtain a global balancing. 17

18 4 Usage case study ROS Radial run out correction techniques Axial dissymmetry correction by bearing area turning Single bearing area turning Two bearings area turning minimum unbalancing option Two bearings area turning no mass info 18

19 4 Usage case study ROS Radial run out correction techniques Axial dissymmetry correction by balancing weights introduction 19

20 4 Future developments Face run out detection on Hirth couplings elsewhere Position [mm] st.dev [mm] Height [mm] Position [mm] 20

21 5 Future developments Error metrics for assessing Hirth quality Example of Hirth profile (drawing) Example of Hirth profile (by calculation) AEN is evaluating several metrics, based on measured data, for assessing Hirth quality: Local errors between measured and theoretical profiles Global errors between measured and theoretical profiles Eccentricity Errors on teeth features Symmetry axis misalignment 21

22 5 Future developments Multi parametric methodology for GT assembly optimization Technique : Assessment of rotor unbalancing by radial runout Partial rotors unstacking Rotor assembly with rotation of a part of rotor disks, choosing which parts have to be rotated to obtain a global balancing 22

23 6 Summary In this presentation we have see: Special tools for measuring dissymmetries blade tips (BMS) axial unbalancing/dissymmetry (ROS) Same HW and SW in factory and field Some correction technique applied in case studies Blade tip grinding to obtain high radial homogeneity of blades tips, which affects the Gas Turbine (GT) performances Rotor Shape balancing by bearing area turning machining and/or weights introduction Rotors unstacking with rotation of a part of rotor disks, choosing which parts have to be rotated to obtain a global balancing. The preliminary results of the R&D AEN project OPAR evolution, a system developed to support decision about corrective actions to be performed on GT rotors 23

24 The end GT ROTOR ASSESSMENT & CORRECTION OF GEOMETRICAL UNBALANCING AND BLADE TIP NONHOMOGENEUS SURFACE Authors: A.Rava (AEN), R.Traverso (AEN), E.Pignone (AEN) A.Pesatori (PoliMI), M.Pastorino (UniGE) Dipartimento di Elettronica e Informazione 24

25 BACK UP 25

26 5 Future developments Multi parametric methodology for GT assembly optimization 26