A gas turbine is a combustion engine at the heart of a power plant that can convert natural gas or other liquid fuels to mechanical energy. This energy then drives a generator that produces the electrical energy that moves along power lines to homes and businesses. Presentation on Condition Based Monitoring for gas turbine engines is discussed briefly.

1. GASTURBINES&
MONITORING
SHARATH C M
BENGALURU

2. Overview:
 Gas turbines  Recommended vibration parameters
 Potential Failures  Vibration parameter measurement
tools
 Predictive Monitoring  intelligent machinery management
decisions
 performance parameters
recommended  sensor selection
 Conclusion
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3. GAS TURBINE ?
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4. Gas turbines are effectively used within the Oil & Gas industry as a high-power
driver for gas compression and power generation.
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5. • Potential Failures have different distribution depending upon the application
(mechanical design, operation range, environment etc.).
Investigations show that around 70% of all failures can be assigned to product faults, i.e.
 Material faults (e.g. due to fatigue or off design)
 Faults in planning
 Manufacturing faults
 Assembly and repair
Most of these faults may be detected before they become critical by a system that combines
vibration and performance monitoring.
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6. End user of the turbine to balance the investment cost, and the
cost of running a predictive maintenance system against;
 Higher production output,
 Less unexpected repairs,
 Optimized maintenance scheduling,
 Optimized machine performance,
Is taken.
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7. GAS TURBINE PREDICTIVE MONITORING
Process parameters are used for making
performance and efficiency calculations.
Vibration parameters are necessary
when judging the condition of the
rotating parts.
By combining vibration and performance data, better diagnostics can be made.
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8. Recommended performance parameters:
 Turbine isentropic efficiency
 Compressor isentropic efficiency
 Compressor isentropic head
 Compressor volume flow
 Data corrections against atmospheric
pressure, ambient temperature, relative
humidity speed and differential
pressure of inlet filter
 Heat rate (the actual heat input)
 Corrected heat rate
 Isentropic head
 Fuel gas consumption
 Air flow
 Gas turbine inlet temperature
 Firing temperature
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9. Recommended vibration
parameters
 Overall vibration level (according to API
standards)
 Rotor synchronous amplitude and phase
measurements (Minimum 1X & 2X)
 Casing and blade passing frequencies
 Journal Bearings – Gap, Orbit
 Rolling element Bearings – Bearing
frequencies and high frequency noise
Vibration parameter
measurement tools
 DC
 Band Pass / Smax measurements
 Dual Time function with limiting filters
 Vector measurements – Selective Magnitude
and Phase
 FFT - Auto spectra with zoom capability
 Selective Envelope Spectra
 CPB Spectra
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10. Monitoring Set-up depends on the installed monitoring equipment and the
monitoring strategy relevant for the specific application.
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11. Monitoring Set-up depends on the installed monitoring equipment and the
monitoring strategy relevant for the specific application.
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13. The goal is to provide the right information to the operations and
maintenance personnel, where the information is accurate and timely
information that can be used to make intelligent machinery management
decisions, i.e.:
 Continue or not?
 If it fails, what are the consequences?
 Can the machine be re-started?
 What should be inspected?
 Is the machine operating efficiently?
 Will it last until next scheduled overhaul/service? 13

14. Gas turbines require vibration sensors:
measuring vibration severity, the direction vibration (reference
sensor) and the motion of the shafts (position relative to bearings
and seals) giving:
• Amplitude • Phase • Frequency
When monitoring shaft vibration on gas turbines displacement sensors are
recommended
The sensor should be selected based on its response curve, frequency range,
sensitivity and noise susceptibility
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15. Bearing cap or case mounted seismic sensors (e.g. accelerometers)
are useful for evaluating casing vibrations
The vibration phase is measured by a reference sensor; either an
infrared or displacement sensor.
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