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Challenges of implementing a reliable and accurate non-intrusive ultrasonic
flow measurement on penstocks at large-scale hydroelectric power
plants
Denis Funk
FLEXIM GmbH
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1 Introduction of ultrasonic clamp-on (USCO) flow measurement: Transit-time technology
Challenges and experiences of a manufacturer implementing USCO flowmeters on penstocks of hydroelectric plants
Selection of transducers
Agenda
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2.1
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2.2 Mounting and coupling
Ambient temperature fluctuations
Verification of the correctness and checkup of the long-term stability of the measurement
2.3
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Flow
Cross section of the pipe
Fluidmechanic Calibration factor
Acoustic Calibration factor
time difference
transit time in the fluid
Re
2a
fl
tV A K K
t
∆= ⋅ ⋅ ⋅&
t∆
lv
UFM
Re
a
fl
V
A
K
K
t
t
∆
&
flt
1. Introduction of ultrasonic clamp-on (USCO) flow measurement: Transit-time technology
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1. Introduction of ultrasonic clamp-on (USCO) flow measurement: Transit-time technology
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2.1 Selection of transducers
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Lambwave
2.1 Selection of transducers
Shearwave
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2.2 Mounting & coupling
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• Welded
transducer
mounting
• Robust
• Tamper proof mounting
• Long-term stable
2.2 Mounting & coupling
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2.3 Ambient temperature fluctuations
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ASME MFC-5.1-2011:
• 4. Uncertainty sources and
uncertainty reduction
“…the flow velocity is calculated
from the transit times; the
sound speed and the angle in
the coupling wedge. A
temperature influence from
temperature dependency of the
sound speed, c, may be
compensated for.”
2.3 Ambient temperature fluctuations
Piezo sensor
Piezo sensorTemperature sensor
Temperature sensor
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3. Verification of the correctness and checkup of the long-term stability of the measurement
Self-diagnostics
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Thank you for your attention!
Denis FunkHead of Market Management Power Generation
FLEXIM GmbH [email protected]
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Backup
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Pipe wall penetrationMulti reflection
2.1 Selection of transducers
Pipe wall resonance
2.1 Selection of transducers
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