We have a boiler plant and steam is generated at following conditions:

Meter Max Flow: 125 TPH
Meter Min Flow: 0 TPH

Steam Transmitter DP range: 0 - 3500mmWC
(i.e., 0 - 3500mmWc corresponds to 0 - 125TPH)

Operating Pressure: 10.5KG/CM2
Operating Temp.: 180-182 Degrees centigrade

Orifice's Beta value: 0.663339756
Viscosity of steam: 0.00015850 Poise
Pipe size: 406.4/381.0 (OD in mm/ID in mm)

Based on this data, would anyone suggest the exact formula for compensation of steam flow? Also can anyone suggest a suitable link on net for downloading steam parameters esp. density of steam at various temperatures?

thanks
au revoir
Rahul

 

This Link may help you out...
http://www.rosemount.com/products/flow/m3095compensated.html

if not your local Emerson Process Management (Rosemount Div) contact can help you.

Thanks,
Roley

 

Once upon a time I bought a copy of "Steam: its generation and use" published by Babcock & Wilcox, and still refer to on occasion.

But when it comes to steam flow, the simplest solution is the ability of high end smart dp transmitters to calculate mass flow. If I recall right, these measure three variables: DP, the absolute upstream pressure and temperature from a thermocouple. With the 3 variables it runs a compensation calculation to end up with mass flow, not volumetric.

We put one on those Honeywell smart multivariable transmitters on our main steam header in 1996 and it hasn't missed a beat since. We did replace the orifice plate in 2003, though. It generates a conventional 4-20mA that we run into the DCS.

John

 

I think it depends what you are going to do with the result of your calculation.

1. For very accurate mass balancing or energy calculations you require steam tables, which are available built in to flow computers such as Yokogawa. (STLD etc.)

2. For boiler control, I installed and commissioned a DCS on a major manufacturer's boiler. I was instructed by the boiler manufacturer to use the standard gas formula. If the steam pressure and temperature does not fluctuate by large amounts, this formula's accuracy is acceptable.

 

You could try to use the program FlowCalc. It can calculate a flow formula with compensation for you. You can also get charts of the output of the compensated flow formula versus flow calculated through ISO 5167 at different levels of temperature and pressure. The program can be found at http://www.controlengineering.se

Regards
Kristian

 

> We have a boiler plant and steam is generated at following conditions:

> Meter Max Flow: 125 TPH
> Meter Min Flow: 0 TPH

> Steam Transmitter DP range: 0 - 3500mmWC (i.e., 0 - 3500mmWc corresponds to 0 - 125TPH)

> Operating Pressure: 10.5KG/CM2
> Operating Temp.: 180-182 Degrees centigrade

> Orifice's Beta value: 0.663339756
> Viscosity of steam: 0.00015850 Poise
> Pipe size: 406.4/381.0 (OD in mm/ID in mm)

> Based on this data, would anyone suggest the exact formula for compensation of steam flow? Also can anyone suggest a suitable link on net for downloading steam parameters esp. density of steam at various temperatures?

Answer
Compensated Steam Flow Fornula Qc=Q*[Square Root of (Pa+1.033/Pd+1.033)*(Td+273/Ta+273)]

Qc = Compensated Steam Flow
Q = Main steam Flow
Pa = Actual Pressure
Pd = Design Pressure
Ta = Actual Temperature
Td = Design Temperature

 

Dear friend

Use following side for your reference

http://www.efunda.com/materials/water/steamtable_sat.cfm

 

> Compensated Steam Flow Formula
> Qc=Q*[Square Root of (Pa+1.033/Pd+1.033)*(Td+273/Ta+273)]

> Qc = Compensated Steam Flow
> Q = Main steam Flow
> Pa = Actual Pressure
> Pd = Design Pressure
> Ta = Actual Temperature
> Td = Design Temperature

=================================

Compensated Steam Flow Formula Qc=Q*[Square Root of (Pa+1.033/Pd+1.033)*(Td+273/Ta+273)]

this formula is for GAS flow compensation, for steam flow pressure/temperature correction there is another formula, can anyone provide that

we also searched standard library of rockwell PlantPAX and found that "PT_Compensation" Block only support correction for gases other than steam and NG. For steam ASME formula and For GAS AGA formula suggested to do compensation.

any help would be appreciated, we have been using 3095MV but those flowmeters are obsolete. we dont have programming software to change flowmeter correction data. we are planning to replace multivariable FT with normal DP FT+PT+TT combination with Compensation formula in Rockwell Compactlogix PLC.

 

What is Pd and Td? design process parameter for example air? or used in the calculation of the flow coefficient?

 

> What is Pd and Td? design process parameter for example
> air? or used in the calculation of the flow coefficient?

Pressure should be in Kg/Cm2, Temp is in Deg C.

 

Thanks for the information.

pls. let me know the unit of Pa & Pd.
unit of Qc & Q.

> Compensated Steam Flow Formula
> Qc=Q*[Square Root of (Pa+1.033/Pd+1.033)*(Td+273/Ta+273)]
>
> Qc = Compensated Steam Flow
> Q = Main steam Flow
> Pa = Actual Pressure
> Pd = Design Pressure
> Ta = Actual Temperature
> Td = Design Temperature
>
>=================================
>
>Compensated Steam Flow Formula Qc=Q*[Square Root of
>(Pa+1.033/Pd+1.033)*(Td+273/Ta+273)]
>
>this formula is for GAS flow compensation, for steam flow
>pressure/temperature correction there is another formula,
>can anyone provide that
>
>we also searched standard library of rockwell PlantPAX and
>found that "PT_Compensation" Block only support correction
>for gases other than steam and NG. For steam ASME formula
>and For GAS AGA formula suggested to do compensation.
>
>any help would be appreciated, we have been using 3095MV but
>those flowmeters are obsolete. we dont have programming
>software to change flowmeter correction data. we are
>planning to replace multivariable FT with normal DP FT+PT+TT
>combination with Compensation formula in Rockwell
>Compactlogix PLC.