Mass flow through Venturi tube 3

[flinana]

Hi,

I have a Venturi tube installed on a superheated steam line. In order to calcula the mass flow I have a couple of questions.
1. does the transmitter have to extract the square root or linear and then which formula would need to be applied to read mass flow and not volumetric flow?


thanks

 

[hacksaw]

fixed the sw, was in the report section, thanks

good luck, btw

 

[hacksaw]

when the calc is run for the pitot using the mfg coefficient: C=0.5403, I get considerably different numbers for the transmitter calibration, enough of a difference to need clarification from the supplier.

also a bit puzzled by the change in flow units from t/h with your other meters to kg/s

 

[flinana]

to convert from t/h to kg/s I just multiply by 3,6, What do you mean?
The pitot from the steam generator uses kg/s and we use t/h.

 

[flinana]

what do you mean by fixed the sw?

 

[hacksaw]

the old formula listed in the report(not used in the calc) included an fh factor. This was removed.

Sorted out the differences in the annubar meter d/p calculations. The calculation at the given flow and pipe size is extremely sensitive to fluid density. I am using an older equation of state with a fluid density that differs from the supplier calc by 0.14%. The accepted equations of state for steam have been improved since the calc was developed.

 

[flinana]

I have opened a warranty claim to our EPC contractor so that they check their Pitot. There cant be 205 tn/h on the pitot and 220 tn/h on our orifice! Its impossible

 

[flinana]

Btw, I forgot to mention that the feedwater flow nozzle long radius high ratio flowmeter at this point is 222 tn/h so it does seem closer with the orifice than with the pitot. Feedwater flow should be same as steam flow or not?

Attached is the FW FM

 

[hacksaw]

remember it only instrumentation, good luck with the project.
no drain hole was assumed


FLOW METER SIZING CALCULATION


Tag no
Service
Fluid Water
Meter ASME Long Radius Flow Nozzle


Pressure 115.000 Barg(116.013 Bar(A))
Temperature 179.0 Deg C
Ambient Pressure 1.013 Bar(A) ( 0 Meters Above msl)
Liquid Gravity (Gf) 0.889
Viscosity 0.160 cP

normal | maximum
Flow 235000 | 250000 kg/hr
Pipe Reynolds No. (Rd) 3936751 | 4188033
Mean Fluid Velocity (Pipe) 5.4 | 5.7 m/s
Line Loss 1.52 | 1.73 (Bar)/100 m
Friction Factor (f) 0.0156| 0.0156
Meter Loss(Installed) 0.46 | 0.52 Bar
Meter Velocity 15.0 | 16.0 m/s


**** METER CONSTANTS ****

Meter Bore (d) 3.1070 @ 20 Deg C
Pipe i.d. (D) 5.1870 Inches
Beta Ratio (d/D) 0.5990 Inches/Inch
Metal Expansion (Fa) 1.0053 (316 Stainless Steel)
Expansion Factor (Y1) 1.0000
Reynolds Factor (Fc) 1.0000
Drain/Vent Corr. (Fh) 1.0000
Discharge Coef. (Cd) 0.99320
Spinks Factor (S) 0.38178


**** TRANSMITTER DATA ****

normal | maximum
Meter Differential (h) 8952.7 | 10132.1 mm w.c.
Flow Rate 235000 | 250000 kg/hr


W (kg/hr) = 255.2 * S * D^2 * Fa * Fc * Fh * Y1 * sqrt( Gf * h )

 

[flinana]

thanks again.