Reasons for fluctuations in the measurement values of differential pressure flow meters
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In the INEOS polypropylene plant, the measured flow rate of propylene returning to the reactor from the recycle gas compressor is subject to fluctuations; the medium flowing in the pipes is propylene, and Rosemount differential pressure flow meters are used on site. It is suspected that there is a problem with the differential pressure gauge, but after pressure testing, the gauge worked normally. The reason for the fluctuations in the measurement values is unknown; the normal manufacturing process is quite stable. Also, the pressure guide tube is relatively long; I’m not sure if that will affect the stability of the measurements. I hope experienced experts can give some guidance. Thank you
I asked the process engineers, and it seems that insufficient heat tracing is the cause; this leads to some liquefaction of propylene in the pressure guiding tube, which may affect the measurements.
I would like to ask experienced professionals: if the heating for an acrylic differential pressure flow meter is insufficient, causing some of the acrylic in the pressure guiding tube to liquefy, will this lead to measurement fluctuations? If that’s the reason, does it mean that all pressure guiding pipes need to be equipped with heat tracing? Is electric heating better or steam heating better?
If the pressure tap is not installed properly, it will affect the measurements. It depends; we need to give it a try
This post was last edited by アブイリンシャン on 2017-11-15 09:22. It seems to be vaporization; check the temperature and pressure at the flow meter – it’s possible that the pipe is too long, resulting in excessive pressure loss (or there might be a small blockage in the pipe that you haven’t noticed). Flow meters of the differential pressure type also incur significant pressure losses, so vaporization may occur right at the flow meter, which is why the readings fluctuate
Are the straight pipe sections before and after the flow meter long enough? The pressure lead pipe should not be too long.
The pressure tap is at seven or eight meters; the other instrument also fluctuates. After moving it, the pressure tap became shorter, but the instrument still fluctuates. It still seems to be due to acrylic accumulation
There should be no problem with the straight pipe section; if there is an issue with it, it can only be attributed to large measurement errors, and it shouldn’t cause significant fluctuations. It seems that the accumulation of propylene is the cause
I can’t figure it out; the boiling point of propylene is -48°C. Why does it still liquefy? Heating is also needed. . . If it’s the concern about the gas-liquid phase, just add a condenser – then the tank will be filled with water, right?