Saturated Steam Flow Measurement Problem

V

Thread Starter

Vinod Ghate

Hello;
We are facing a problem in steam flow measurement. We have a saturated steam flow meter (Orifice based) at plant Inlet. It receives steam from boiler at a press. 8- 12 bar press. Orifice has been designed for 15 Kg/Cm2(g) press. 18,000 Kg/hr flow. This indication is Press Temp. compensated in DCS.

Downstream of this, there is PRV which reduces steam press. to 6.5 Kg/Cm2(g) & there are Orifice-based flow meters at this press. giving flow to Columns.

Main steam flow meter reading shall match to sum of all individual column flow meter, which is not happening. When press is @ 9 Kg/Cm2(g)main steam flow is more by 1300 Kg/hr & when press increases to @12 Kg/Cm2(g) main steam flow meter shows flow more only by 400 Kg/hr. There is no variation in indication of downstream flow meter as they get constant press. of 6.5 Kg/Cm2(g)Down stream flow meters doesn't have any compensation.

We are unable to explain why there is a difference. Pl. help us to understand the same.
 
You might want to check and confirm that the transmitter is not square rooting the signal AND the DCS is also square rooting the transmitter's square root signal. It's been known to happen more than once.
 
A more complete statement of the installation for a proper evaluation. All you've provided is the DCS version to borrow a phrase.
 
Top