FC Flow Computer
99
ILVA Flowmeter - This meter type requires an initial linearization using the lineariza-
tion table. In addition, the following specialized corrections are required.
For Gas/Steam Expansion (imperial)
Y = 1 – (115.814 • (dp / p) • 0.0001)
Where:
Y = gas expansion correction (NOTE: Y=1 for liquid)
dp = differential pressure - inches water gauge
p = upstream pressure - psia
For Reynolds Number (volumetric calculations for Gas/Steam)
Cre = (1 – (n / Qn)
-1
to
a
maximum
value
of
m
Where:
Cre = Reynolds number correction (NOTE Cre = 1 for liquid)
Qn = nominal water volumetric flowrate (column 6)
m = (see table below)
n = (see table below)
Meter Size
n
m
DN50
2.53
1.200
DN80
0.64
1.125
DN100
0.21
1.100
DN150
0.13
1.067
DN200
0.07
1.050
The final gas expansion and Reynolds number correction is:
Qc = Qn • Y • Cre
For Volumetric Calculations: (calculate the density corrected volumetric flowrate):
Qd = Qc • (Dn / Da)
0.5
Where:
Qd = density corrected volumetric flowrate
Qc = nominal water volumetric flowrate (column 6) corrected for
Reynolds Number and gas expansion effects.
Da = actual flowing density of working fluid
Dn = nominal density of water at reference conditions
Once corrected for density a further correction is required to take into account the
effect of temperature on the ILVA primary element.
Temperature Compensation
For Volumetric Calculations: Using the value of Qd derived above, the temperature
corrected flowrate can be calculated: Qa = ((Ta - Tref) • 0.000189 • Qd) + Qd)
Where:
Qa = actual volumetric flowrate
Qd = density corrected volumetric flowrate (from above)
Tref = reference temperature in °C (generally 20°C)
Ta = actual flowing temperature of working fluid (in °C)
It is possible to convert from a mass flowrate to a volumetric flowrate and vice versa
using the following simple formula: Ma = Qn • Da
Where:
Da = actual flowing density of working fluid
7.3.13
ILVA Flow Meter
Equations
Содержание FC
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