Seeking advice on temperature and pressure compensation for orifice plate flow meters
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I have a simple question: Regarding the measurement issues with steam orifice plate flow meters, the temperature of the steam at 0.5 MPa is currently low (around 200°C). The originally set steam compensation temperature was 300°C, which results in significant measurement errors. If we now want to change the compensation temperature to 220°C, does it require replacing the orifice plate? Because there is a clause regarding operating temperature in the orifice plate design document; I think it would be sufficient to change the temperature for temperature and pressure compensation in the DCS to 220°C. How should this be done? Thank you!
The actual steam temperature has decreased, and with the same mass flow rate, the volume flow rate drops; this will at least prevent the orifice plate from exceeding its limits, so there is no need to replace it. There’s no problem with changing the compensation temperature to 200°C; it should be 200°C exactly, and there’s no need to use some intermediate value like 220°C.
Just compensate for the actual temperature; there is no need to replace the orifice plate
The compensation temperature is originally the theoretical medium temperature of that pipeline; it can be changed accordingly. Steam temperature compensation is based on IFC1967, and it allows for the compensation of any temperature
There is no fixed value for this temperature and pressure compensation
The DCS or integrator should be entered with the design values, while time, temperature, and pressure should be entered based on the actual measurement results. Unless the changes are substantial and exceed the scope specified by the compensation procedure. If there is a large difference between the actual operating parameters and the original data of the orifice plate and you want to make corrections, leave it to the manufacturer to perform the recalculation; you can then use the new data, considering the original data as invalid.
If it’s still saturated steam, the temperature and pressure compensation is already built into the algorithm, so no modifications are needed
At a pressure of 0.5 MPa and a temperature of 300°C, the density of steam is approximately 2.3 Kg/N3; at 0.5 MPa and 220°C, it is about 2.7 Kg/N3; and at 0.5 MPa and 200°C, it is around 2.8 Kg/N3. I hope these three values will be helpful for your judgment.