How to solve resonance of control valves caused by high-precision mass flow meters
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About 60 cm next to the flow meter on the left side, there is a control valve used for manually adjusting the flow rate to keep it stable; it cannot adjust automatically, and the flow rate fluctuates greatly in automatic mode. The PID parameters are the default settings set by the control system: P 100, I 60, D 0. Noise can be clearly heard from the control valve; when the flow meter is powered off, the noiseほぼ disappears. It is suspected that the flow meter caused resonance in the control valve, resulting in its inability to adjust automatically. The control valve operates normally; how to resolve this issue? 641
This post was last edited by Darija on 2020-12-5 06:33. Flowmeters have requirements regarding installation and vibration; I haven’t heard that it affects control valves. When in manual mode, the flow rate is normal, indicating that there is no issue with the flow meter. Is there a problem with the control valve itself, or are there issues with the PID parameters? Try adjusting the PID parameters; generally, these parameters need to be tweaked. From the flow graph, it is clear that the parameters are not appropriate. Your diagram is really not informative at all.
The probability of resonance between a valve and a Coriolis mass flow meter is very low, but it cannot be ruled out. Recommendation 1: Adjust the opening degrees of the manual valves before and after the control valve, so as to change the operating opening degree of the control valve from its previous value for observation purposes ； 2. Check whether the valve core structure of the control valve itself, along with the pre-tightening force of the actuator, are suitable for the current differential pressure; in particular, it may be that the selected cylinders or diaphragm heads are too small. 3. Positioner parameter issues.
First, it could be electromagnetic interference from your electric heat tracing; second, the control valve itself may have poor resistance to interference; third, the shielding grounding might not be in good condition
Check whether there is any issue with the AO analog output signal. Second, examine the PID parameters and slow down the pulse output speed. Third, check if there are problems with the valve positioner; wear and tear over time due to prolonged use of the control air circuit valves can cause oscillations in the positioner. The fact that the manual valve and flow meter show no movement indicates that there are no issues
It looks like a Coriolis flow meter. Vibration could be caused by the control valve. Check at the same time whether there is a lack of fluid in the flow meter; it could be caused by the excitation sensor, and the empty tube experiences significant vibration
This post was last edited by qugd on 2020-12-7 at 10:29. This is likely resonance in the pipelines and valves caused by the vibration of the excitation coil inside the Coriolis mass flow meter. As can be seen from the diagram, there are no suitable support or fixing measures between the pipelines and the two flow meters; this is a problem that arises during the installation of the mass flow meter, and it allows resonance to spread to the surrounding equipment and pipelines. It is recommended to provide reliable support near the locations where the pipelines and flow meters are installed; in addition, a support should be placed between the flow meter and the valve to prevent the transmission of vibrations, thereby eliminating resonance. During the installation of pipelines and flowmeters, stress or lack of support can cause resonance between the mass flowmeter and the surrounding equipment.
The PID parameters are incorrect; reduce P further, make I less than 10, and try again.
Manual adjustment works fine, which indicates that the valve and flow meter are still compatible. It’s likely that the PID tuning parameters haven’t been set properly; this can be adjusted by setting them within an optimal range so that automatic regulation can take place.
Start by adjusting the PID parameters