Re: [foxboro] Steam FLow Calc
- From: Corey R Clingo <clingoc@xxxxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Wed, 20 Apr 2005 10:47:34 -0400
We have had an ongoing discussion here about compensation methods for
steam flow. In our DCSs here, for compensation methods that actually run
in the controller, you typically have a choice of either ideal gas [i.e.,
sqrt(Pf/Pd * Td/Tf)], or using two characterizer-type blocks (CHARC on
I/A) to give density compensation factors for temperature and pressure
variations based on linear interpolation of steam table data.
We put together a couple of investigative spreadsheets to compare the
methods. We found that for very high accuracy, or for more widely-varying
flowing conditions, the characterizer approach works best. For lower
accuracy requirements, or if your temperature and pressure stay close to
your design conditions, ideal gas is fine. Of course the decision point
is still being debated, and your point of view depends on whether you work
for the utilities plant or one of the production units :)
Of course this all may become moot, as smart transmitters that have
built-in physical properties data, or measure actual mass flow, become
more widely available.
Corey Clingo
BASF Corp.
"BrianLong" <blong@xxxxxxx>
Sent by: foxboro-bounce@xxxxxxxxxxxxx
04/19/2005 04:56 PM
Please respond to foxboro
To: "Foxboro"
cc:
Subject: [foxboro] Steam FLow Calc
We are using a CALC block to calculate steam flow. The calculation is not
as accurate as I'd like. Does anyone have an accurate "standard" way to
calculate steam flow in K# / HR.
Thanks,
Brian Long
Arkansas Kraft
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