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Vibration Monitoring for Gas Turbines Steve Sabin – SETPOINT Vibration Jan 2015.

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Presentation on theme: "Vibration Monitoring for Gas Turbines Steve Sabin – SETPOINT Vibration Jan 2015."— Presentation transcript:

1 Vibration Monitoring for Gas Turbines Steve Sabin – SETPOINT Vibration Jan 2015

2 About content… To activate the links and animated content in these slides, please run in “Slide Show” mode

3 About SETPOINT… 20 minutes from Lake Tahoe Machinery ProtectionCondition Monitoring

4 About me… BSEE from Oregon State University 22 years with Bently Nevada Sales Engineer in Western Canada TransCanada Pipelines, NOVA Pipelines, etc. ORBIT magazine executive editor Marketing Director Lots and lots of articles / app notes / white papers 5 years with SETPOINT Secretary for API th and 5 th editions

5 Links to Resources API th edition 1Q2005 ORBIT magazine Gas Turbine Vibration Monitoring article Georgia Tech Short Course on Combustion Instability (“Humming”) Video on how SETPOINT uses the PI System in place of stand-alone condition monitoring software NOTE: You must be in PowerPoint Slide Show mode for these links to be active

6 Monitoring Fundamentals

7 The Industry Standard – API 670 Details sensors, monitoring systems, documentation requirements, and installation practices Specifies accepted “good engineering practice” for machinery protection Excellent starting point for company-specific vibration monitoring standards in all industries (not just O&G) Developed and refined over five successive editions since first published in 1976 by a broad community of end users, instrument manufacturers, and machinery OEMs Originally focused on bearing vibration, axial (thrust) position, bearing temperature, and gearbox casing vibration – expanded to include surge detection, overspeed, condition monitoring, and recip-specific measurements

8 Distinctions Protection SystemsCondition Monitoring Systems Purpose API 670 Scope Displays Platform

9 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. API 670 Scope Displays Platform

10 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. Information Delivery High-resolution data for machinery engineers to analyze for run/don’t run decisions, outage planning, root cause diagnostics, etc. API 670 Scope Displays Platform

11 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. Information Delivery High-resolution data for machinery engineers to analyze for run/don’t run decisions, outage planning, root cause diagnostics, etc. API 670 ScopeNormative Historic focus of 1 st through 5th editions Displays Platform

12 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. Information Delivery High-resolution data for machinery engineers to analyze for run/don’t run decisions, outage planning, root cause diagnostics, etc. API 670 ScopeNormative Historic focus of 1 st through 5th editions Informative New in 5 th edition as an “Informative Annex” Displays Platform

13 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. Information Delivery High-resolution data for machinery engineers to analyze for run/don’t run decisions, outage planning, root cause diagnostics, etc. API 670 ScopeNormative Historic focus of 1 st through 5th editions Informative New in 5 th edition as an “Informative Annex” DisplaysBasic (bargraphs / status / trends) Intended for operators – often via DCS screens; local display at racks are optional but frequently included Platform

14 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. Information Delivery High-resolution data for machinery engineers to analyze for run/don’t run decisions, outage planning, root cause diagnostics, etc. API 670 ScopeNormative Historic focus of 1 st through 5th editions Informative New in 5 th edition as an “Informative Annex” DisplaysBasic (bargraphs / status / trends) Intended for operators – often via DCS screens; local display at racks are optional but frequently included Detailed (waveforms, orbits, spectrums, etc) Intended for machinery experts; often via remote access to a local server in the plant collecting and storing the data Platform

15 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. Information Delivery High-resolution data for machinery engineers to analyze for run/don’t run decisions, outage planning, root cause diagnostics, etc. API 670 ScopeNormative Historic focus of 1 st through 5th editions Informative New in 5 th edition as an “Informative Annex” DisplaysBasic (bargraphs / status / trends) Intended for operators – often via DCS screens; local display at racks are optional but frequently included Detailed (waveforms, orbits, spectrums, etc) Intended for machinery experts; often via remote access to a local server in the plant collecting and storing the data PlatformHardware Intended strictly for machinery protection; usually rack- based; not simply transmitters into PLCs or DCSs

16 Distinctions Protection SystemsCondition Monitoring Systems PurposeAuto-Shutdown Protection High-integrity “alert” and “danger” alarms suitable for automatically tripping the machine – no operator intervention required. Information Delivery High-resolution data for machinery engineers to analyze for run/don’t run decisions, outage planning, root cause diagnostics, etc. API 670 ScopeNormative Historic focus of 1 st through 5th editions Informative New in 5 th edition as an “Informative Annex” DisplaysBasic (bargraphs / status / trends) Intended for operators – often via DCS screens; local display at racks are optional but frequently included Detailed (waveforms, orbits, spectrums, etc) Intended for machinery experts; often via remote access to a local server in the plant collecting and storing the data PlatformHardware Intended strictly for machinery protection; usually rack- based; not simply transmitters into PLCs or DCSs Software Generally computer-based; uses Microsoft business/consumer operating systems

17 Radial Vibration Displacement (mils pk-pk) Y-probe X-probe

18 Casing Vibration Velocity (in/sec 0-pk)

19 Axial (Thrust) Position Gap (mils) Can configure for: increasing gap upscale* (normal) increasing gap downscale (counter) *increasing gap upscale depicted here NORMAL COUNTER Probe

20 Eccentricity Indicates amount of shaft bow Typically measured at a shaft extreme Slow-roll speeds (well below rotordynamic effects)

21 Phase / Speed Pulses/min (rpm)

22 Reverse Rotation CW Rotation

23 Reverse Rotation CCW Rotation Peak reverse speed # of reverse rotations

24 Temperature Measurements Bearing metal temperature measurements are covered in API 670 and are often included in the machinery protection system, since they are machinery temperatures, not process temperatures Other temperatures in machinery are sometimes measured as well: Electric motors – winding temperatures Gas turbines – exhaust temperatures Recip compressors – valve temperatures

25 Conceptual Overview Sensors Turbine Generator Machine Cases Bearings Shafts Monitors Machinery Protection System

26 Typical Probe Mounting image courtesy of Elliott Group

27 Typical Transducer Arrangement

28 Typical System Arrangement 8 x 4-channel monitors for 30 vib’n, thrust, speed, and phase inputs 3 x 6-channel monitors for 16 temp inputs 4-20mA and relay outputs Redundant MODBUS® links with DCS Fully redundant power connections to 24Vdc supplies Condition Monitoring SW Local HMI

29 Typical Local HMI

30 Typical Condition Monitoring Plots Orbit / Timebase Polar Trends Bode

31 Typical Condition Monitoring Plots Waterfall Spectrum Alarm List

32 Gas Turbine Classifications

33 Classifications Industrial (i.e. Heavy Duty)Aeroderivative Fluid-film bearings Solely for industrial use Heavy / Large /Foundation-mounted Always single-spool; often single-shaft Conventional maintenance Rolling-element bearings Adapted from aircraft engine design Lightweight / Compact / Skid-mounted Often multi-spool GG driving a PT Swap-out maintenance SGT6-2000E (103 MW) FT4000 SWIFTPAC® (60 MW)

34 Sub-Classifications “Light” IndustrialHybrid All-industrial components Fluid-film bearings Skid-mounted / packaged Part-aero / Part-industrial components Mix of bearing types Multi-spool/shaft MS6001FA (LP compressor) + LM6000 (HP compressor and HP/IP turbine) Centaur 40 (50 MW) LMS100 (~100 MW)

35 Major Manufacturers IndustrialAeroderivative

36 Brands, Acquisitions, and Mergers x 10 6 (but mostly convergence)

37 Monitoring Considerations

38 Aeroderivative Nomenclature (Image courtesy of ORBIT magazine)

39 Multi-Spool Aeros HP Turb LP Turb HP Comp LP Comp Aerodynamically-Coupled Gas Turbine 2-Spool Gas Generator Driven Machine (pump, generator, compressor, etc.) Turb Power Typical 1-Spool GGTypical 2-Spool GG (shown in figure below) Typical 3-Spool GG LM2500GE LM6000Rolls-Royce RB211 GE LM1600Rolls-Royce TRENT LP Spool HP Spool

40 Monitoring Philosophies IndustrialAeroderivative Fluid-film bearings  Proximity Heavily instrumented  6-12 sensors Conventional maintenance Engine problem = loss of product Relatively OEM-independent Relatively “clean” vibration signals Rolling-element bearings  Siesmic Lightly instrumented  1-3 sensors Swap-out maintenance Engine problem = loss of life Extremely OEM-dependent Extremely noisy vibration signals (lots of signal processing required)

41 Recommended Monitoring MeasurementDescription MINIMAL TRANSDUCER SUITE Radial Bearings Thrust Bearings Shaft Speed / Phase X-Y proximity probes Dual-voting axial probes Once-per-turn phase reference probe SUPPLEMENTAL FOR LARGE FRAME SIZES Casing Vibration* Eccentricity Seismic velocity at bearing caps Proximity probe for rotor sag or bow INDUSTRIAL * NOTE: GE frame-type gas turbines use only seismic bearing cap vibration for shutdown protection; proximity probes on radial bearings are used only for condition monitoring.

42 Recommended Monitoring MeasurementDescription ENGINE Casing Vibration Shaft Speed Seismic at OEM-specified locations with OEM-specified filtering (primarily 1X) Multi-tooth gear for each spool speed POWER TURBINE Rolling Element Bearings Casing Vibration Fluid Film Bearings Radial Bearings Thrust Bearings Shaft Speed/Phase Seismic velocity at OEM-specified locations X-Y proximity probes Dual-voting axial probes Once-per-turn phase reference probe AERODERIVATIVE

43 Typical OEM-Specified Schema GE IDM FOR AERODERIVATIVES 1.Monitor each 1X for blade loss events Fast (100 mS) danger level time delay trip 1 second time delay on alarm levels 2.Monitor filtered Hz wideband for “other” engine problems 10 second time delay alarm 10 second danger level to trip 3.Have unfiltered accel signal available for diagnostics (not used for monitoring) Monitor Accel Interface Module  Wideband Hz (100mV/ips)  Raw Acceleration (10 mV/g) Spool Speed x gear ratio  1X velocity tracked at spool speed 50 pC/g Control Room Field HOT WARM COOL

44 Why Velocity and not Accel?

45 Exhaust Gas Temperature Ideally measured at turbine inlet, (but usually too hot there!) Measured at tubine exhaust plenum instead (via thermocouples placed circumferentially) Indicates problems in hot gas path Can be used for both control and monitoring Typical exhaust gas temperature profile (Screen capture from GE System 1 software)

46 Combustor Instability (Humming) Huge issue with DLE engines Excellent short course by Georgia Tech’s Tim Lieuwen (click on screen at right for link to course slides)

47 “Humming” Monitoring Monitored with dynamic pressure transducers observing pulsations in combustor cans – often with stand-off tubes Proprietary OEM schemas for sophisticated narrow-band frequency monitoring (often 12-pole or better roll-off required) Used as part of feedback control loop to adjust fuel mixture if humming occurs Combustion Control “Humming” Monitor Combustor Pressure Sensor Control Target: “As lean as possible without humming”

48 Typical Gas Turbine Transducers High-Temperature Moving-Coil Velocity Sensor (Metrix 5485C) High-Temperature Accelerometer Sensor (Metrix SA6350) Proximity Sensor (Metrix MX2030) High-Temperature Pressure Sensor (Kistler)

49 Recommended Reading

50 Q&A


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