epri-steam turbine generator notes

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July 2008

Fossil and Nuclear Steam Turbine-Generators

ContentsUpgrade to Guide for On-Line Testing and Monitoring of Turbine Generators .................................................................................. 2 Shutdown Protection of Steam Turbines Using Dehumidied Air ............. 3 Advanced Labyrinth Seal Project ...................................................... 3 Additions to Guidelines for Reducing the Time and Cost of TurbineGenerator Maintenance Overhauls and Inspections ............................ 4 EPRI Turbine-Generator Program Holds 2007 Steam Turbine-Generator Workshop/Vendor Expo and Summer 2007 Users Group Meeting....... 6 EPRI Turbine-Generator Users Group Holds Winter 2008 Workshop/ Meeting in San Diego ................................................................... 6 Tracking Laser Coordinate Measurement System Application Project Completed .................................................................................. 7 Boiler/Reactor Feedpump Turbine Rotor End-of-Life Project .................... 7 The Effect of Organics/Amines on Turbine Performance ....................... 7 Turbine and Generator Compliance to NERC Standards Interest Group Workshop ................................................................................... 8 Evaluation of Low-Pressure Turbine Stator Coatings to Reduce Erosion on Rotor Blades ............................................................................ 8 Reference Book for Steam Turbine-Generator Products ......................... 8 Generator High-Voltage Bushing Installation Guide.............................. 9 Non-Intrusive Methods to Validate NERC Standards: Steam Turbine Frequency Response (MOD-027)................................................... 10 Inspection Criteria for Generator Rotors Subjected to Abnormal Negative Sequence Current .......................................................... 10 New Turbine-Generator Projects Delivered in 2007 ...........................11 Fifth EPRI Turbine-Generator Program Technology Transfer Workshop and Summer 2008 TGUG Meeting ................................................12 Productivity Improvement Expert Reviews 2008 .................................12 Improving the Financial Risk of an Aging Turbine-Generator Fleet ..........12 Steam Turbine Valve Actuator Condition Assessment Guide .................13 Valve Metallurgy Guides for U.S. and International Turbine Units...........14 Additions to the Turbine-Generator Preventive Maintenance Database ...................................................................................15 Evaluation of Electrohydraulic Control Fluid ......................................15 Steam Turbine Bolting Maintenance Guide .......................................16 Looking Forward: Program 65 and NSTI ..........................................17 Stress Corrosion Cracking and Corrosion Fatigue Workshop to Be Held .....................................................................................18 2009 European TGUG Workshop and Meeting ...............................18 2008 Boiler and Reactor Feed Pump Turbine (B/RFPT) Workshop ........18 Turbine-Generator Supplemental Projects ..........................................19 Axial Entry Disk Blade Attachment NDE Performance Demonstration .....21 Determination of Parameter for 12% Cr Turbine Blades Using Fatigue Sensor Technology ............................................................21 Guide for Inspection of Low-Pressure Turbine Blades .......................... 22 Optimization of Fatigue Sensor Measurement for Curved Blade Surfaces .................................................................................... 22 Upcoming Events ........................................................................ 23 Program Staff ............................................................................. 23 Steam Turbine Blade Failure Root Cause Analysis Guide .................... 23

Mechanical Hydraulic Control System Maintenance Guide in ProgressTurbine mechanical hydraulic control (MHC) systems are still in wide use today on units that are 3050 years old. These are inherently reliable control systems, but they require knowledge of the expected wear characteristics of mechanical components and system setup procedures. Work force changes by plants and equipment suppliers have reduced the level of expertise that can be applied to adequately maintaining and troubleshooting MHC systems. In response to these issues, early this year, work began on completion of an MHC system maintenance guide. The report will be completed by March 2009.

Typical Cam Shaft/Roller MHC System Controls

This technical report will detail basic MHC operation, inspection, setup, troubleshooting, and maintenance. It will help new systems engineers become familiar with the problems and corrective actions needed to keep MHC-related unavailability low. The intent of the report is to cover the MHC devices for the General Electric (GE) fossil and Westinghouse fossil steam turbine valve applications.continued on page 2

Mechanical Hydraulic Control System Maintenance Guide in Progress continued from page 1

Because just six nuclear units in the world still employ these types of turbine control systems (as opposed to the more modern electrohydraulic control systems), the initial report will contain only limited information about nuclear units. As the project progresses, we will investigate the possibility of adding more nuclear MHC information to the final report. Including nuclear information greatly expands the original scope of the project. The current outline of most of the information to be included in the report is as follows: 1. Technical Description. This section will include a general description of the GE, Westinghouse 300#, and Westinghouse 150# MHC systems, with an emphasis on front standard (pedestal) components, lube oil tank components specifically related to control functions (but excluding the lube oil system itself), valve hydraulic cabinet components, and mid-standard components. The components included are as follows: a. For GE units: speed/load changer, load limiter, speed governor, secondary speed relay, acceleration relay, secondary pilot valve, linkages, cutout governor, initial pressure regulator, stop valve bypass valve controller, intercept valve (IV) speed governor, IV dashpot breakdown link, overspeed trip, backup overspeed trip, main stop valve/reheat stop valve trip devices, trip anticipator, test devices, vacuum trip, thrust bearing trip device, electrical trip interface, steam seal regulator, main shaft oil pump, and control rotor (gear on a few units) b. For Westinghouse (150# and 300#) units: speed/load changer, auxiliary governor, load limit valve, oil impeller, throttle pressure regulator, governor emergency trip valve, throttle valve controller, throttle valve servomotor, overspeed trip valve, trip manifold, main oil pump, control valve (CV) servomotor, IV servomotor, multiple orifices and check valve, and control rotor

2. Inspection. This section will include inspection criteria for the GE and Westinghouse turbine control devices. Copies of data sheets used to record measurements and condition will be included. The criteria for inspecting the controls system will be given. Included will be common adjustments, such as setting (measuring) regulation, CV crack point, and overspeed set points. 3. Maintenance. The maintenance section will include preventive and corrective maintenance tasks for the GE and Westinghouse turbine control devices. Applicable procedures for disassembly, repair, and reassembly of the components will be included, and any special tooling will be listed. Any safety considerations for working on the control devices will be given. Included will be references to partial upgrades or modifications that have typically been performed. 4. Post-Maintenance Commissioning. This section will describe activities required to set up and perform preoperational checks on the controls system prior to starting the unit following a major outage, whether or not major work was performed on the controls system. 5. Troubleshooting. This section will include a guide to troubleshooting operational problems. Common operational problems, symptoms, causes, and solutions will be included. For more information on this project, contact Alan Grunsky, 704.595.2056, agrunsky@epri.com.

Upgrade to Guide for On-Line Testing and Monitoring of Turbine GeneratorsThe EPRI report Guide for On-Line Testing and Monitoring of Turbine Generators (1006861), released in 2002, provides information about failure mechanisms for all major generator manufacturers and identifies the most appropriate on-line detection systems. The objectives of the project are to add guidance for off-line testing and to refine the assignment of appropriate failure mechanisms by including age and duty cycle of the generator. The report will be available no later than December 31, 2008. For more information, contact Jan Stein, 650.855.2390, jstein@epri.com.

Steam Turbine-Generator NotesIs published by the Electric Power Research Institute's (EPRI's) Fossil and Nuclear Steam Turbine-Generator Program 1300 W.T. Harris Blvd., Charlotte, NC 28262, fax 704.595.2867 NSTI/Program 65 Contact: Alan Grunsky, 704.595.2056, agrunsky@epri.com

Steam Turbine-Generator Notes

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July 2008

Shutdown Protection of Steam Turbines Using Dehumidied AirEPRIs Program 88 (Heat Recovery Steam Generators), Program 64 (Boiler and Turbine Steam and Cycle Chemistry), Program 65 (Steam Turbines, Generators, and Balance-of-Plant), and the Nuclear Steam Turbine-Generator Initiative released a report on the use of dehumidified air in protecting steam turbines during shutdown. The report, published March 2008, is Shutdown Protection of Steam Turbines Using Dehumidified Air (