Application of Ultrasonic Air Flow Measurement to Industrial Gas
Post on 03-Feb-2022
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realtimepower.net
Application of Ultrasonic Air Flow
Measurement to Industrial Gas Turbines
Dr. A.R. Boucher C.Eng. MIET
Technical Director
Real Time Power, Inc.
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Outline
• Introduction
• Principle of Measurement
• System Description
• Uncertainty Analysis Example
• Results from High and Low Load Operation
• Real-Time Heat & Mass Balance
• Benefits to End Users
• Conclusions
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duct factor = average velocity in plane P / average velocity along vector L
velocity direction is vertically down
(width of vector L exaggerated in this diagram)
Calculation of Duct Factor
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Uncertainty Analysis Example
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Probe tip to probe tip distance = 3.200 m,
Average air flow angle across path = 50°,
Average air speed = 26.5 m/s
Speed of sound = 345 m/s
Uncertainty in distance = ±2 mm
Uncertainty in timing = .±2 μs
Air speed along path = 26.5 x cos(50°) = 17.03 m/s
Upstream time of flight = 3.200 / (345 – 17.03) = 9757 μs
Downstream time of flight = 3.200 / (345 + 17.03) = 8839 μs
Time difference = 918 μs
Maximum worst case reading = 17.12 m/s (+0.48% worst case error)
Minimum worst case reading = 16.95 m/s (-0.52% worst case error)
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Summary of Correlations
New Signal Existing Signal Correlation %
Air Speed
IGV Position Nonlinear 99.16%
Air Vol Flow Rate Compressor Pressure
Ratio/Density
Linear 98.42%
Air Mass Flow Rate Compressor Discharge
Pressure
Linear 98.46%
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Real-Time Mass Balance
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Accurate prediction of
exhaust gas oxygen
concentration
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Real-Time Mass Balance
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Accurate prediction of
exhaust gas oxygen
concentration
Twin gas turbines
running at same load
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Real-Time Heat Balance
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Accurate prediction of exhaust gas temperature
Exhaust gas temperature prediction validates TIT estimate
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Exhaust Gas Temperature Prediction
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Temp Limit computed from Press Ratio
Temp Pred determines when max load is reached
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Benefits to End Users
• Max Load & Heat Rate Forecasting
• Min Load & Heat Rate Forecasting
• Real-Time Performance Monitoring
• Troubleshooting Performance Issues
• Early Detection of Potentially Serious Problems
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1X1 Unit Summer Max Load Prediction
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Forecasted max load
Traders can schedule the
unit for the next 72 hours
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2X1 Unit Summer Max Load Prediction
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Max load with evap coolers running
Requires accurate prediction of
evap cooler performance!
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2X1 Unit Winter Max Load Prediction
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System correctly predicts
that EGT limit would
be reached at 99% load
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2X1 Unit with Duct Burners
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System correctly predicts
maximum load with evap coolers
and duct burners running
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Conclusions
• Accurate measurement of air mass flow rate is
possible with ultrasonic technique
• Allows engine and unit performance to be
monitored and predicted with high levels of
accuracy and confidence
• Allows performance issues to easily and quickly
identified, and provides early warning of
potentially serious problems
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