User manual

Toolbox 32 User Manual 1.47d www.cse-semaphore.com/mykingfisher
Page
95
Example:
Temperature 0
o
C
Pressure 0.6894757 Mpa
Mole N2 0.002595
Mole CO2 0.005956
Specific Gravity 0.581078
Reference Temperature 15.56
o
C
Reference Pressure 0.101560 Mpa
Result: Compressibility=0.982387, Status=0.
AGA-7 Gas Flow
This formula uses the compressibility output from the AGA-8 block and can be written in ladder to evaluate
the AGA-7 gas flow (note: an example configuration is available from www.cse-
semaphore.com/mykingfisher).
Qv = Qf x P/Pgr x Tgr/T x Zb/Zf
Qv = Volumetric flow, cubic metres/second
Qf = Flowrate at flowing conditions, cubic metres/second
P = Pressure, MPa
Pgr = Reference pressure for specific gravity, MPa
T = Temperature,
o
C
Tgr = Reference temperature for specific gravity,
o
C
Zb/Zf = Compressibility factor (output from AGA-8 block)
AGA-3 Gas Flow
The AGA-3 gas flow can be obtained by writing the following formula in ladder logic (note: an example
configuration is available from www.cse-semaphore.com/mykingfisher):
Qv = N1 * Cd * Ev * Y * d^2 * sqrt (dP / p)
Qv = Volumetric flow
N1 = Unit conversion factor (orifice flow)
Cd = Orifice plate coefficient of discharge
Ev = Velocity of Approach Factor = 1 / sqrt ( 1 - b^4 )
b = Orifice bore to meter tube diameter ratio = d / D
d = Orifice plate bore diameter = dr * ( 1 + a * ( Tf - Tr) )
dr = reference orifice plate bore diameter at Tr
a = linear coefficient of thermal expansion
Tf = temperature of fluid at flowing conditions
Tr = reference temperature (eg. from analog input channel)
D = Meter Tube internal diameter = Dr * ( 1 + a * ( Tf - Tr) )
Dr = reference meter tube internal diameter at Tr
Y = Expansion factor
dP = Orifice differential pressure (eg. from analog input channel)
p = Density of fluid at flowing conditions