What are the causes of fluctuations in the main steam valve of a turbine? ? ?
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This post was last edited by Li Yakun on 2019-3-6 at 23:32. Green represents the steam pressure, yellow represents the compressor speed, and red indicates the opening degree of the main steam valve. Images cannot be uploaded for now; they will be uploaded later. During operation, the main steam valve of the turbine experiences fluctuations from time to time, with the speed sometimes dropping by 800 RPM instantly. I seek advice from experts,,,
Excuse me, I can’t see your pictures. Are there any changes in the processing parameters during fluctuations? For example, does the steam pressure or the compressing medium change?
Fluctuations in the main control valve will inevitably cause fluctuations in speed. There are several main reasons for this issue: 1. The intake parameters (mainly flow rate, pressure, temperature, etc.) fluctuate significantly ； 2. Sticking of actuating mechanisms: such as hydraulic motors, electro-hydraulic converters, etc ； 3. There are issues with the speed control system itself or the PID settings are inappropriate; adjustments are required ； 4. Signal interference.
After half a day of trying, I still couldn’t upload the images; I’m sorry. The steam pressure remains relatively stable, with no significant changes in its trend. Before the fluctuations occur, the actual rotation speed is about 50 revolutions higher than the target speed, which causes the main steam valve to keep closing. When it closes to a certain extent, the main steam valve opens suddenly, resulting in a decrease in rotation speed and an increase in steam pressure
Hello, third point: If it’s a problem with the speed control system itself or the PID settings are not appropriate, from which aspects can this be verified? It can’t be explained just based on this one point alone, right? If adjustments are needed, we can figure out how to make them – we can give it a try! Article 4: Signal interference – what are its sources of interference? Thank you! ! !
1. Questions about PID: The PID settings are located within the governor, and they can be adjusted dynamically as the unit is in operation. Adjustment should be done slowly (generally, the speed fluctuation should remain within 100 rpm; this range can be achieved through such adjustments) ； 2. Questions regarding signal interference: interference caused by the proximity of strong and weak electrical currents, interference caused by the proximity of excitation equipment, and interference resulting from a lack of separate grounding, etc. All of these can cause fluctuations in speed; whether they are the main causes can only be determined by an on-site inspection.
If the fluctuations in the speed of this machine can be attributed to factors other than process changes, such as fluctuations in load, steam pressure, and temperature, then it is due to fluctuations in the speed control system. So, regarding fluctuations in the speed control system, is your secondary oil pressure synchronized with the voltage? Do you have a wrong throttle? What is the rotational speed of the faulty throttle spool? Is the control oil pressure stable? The more specific parameters a friend provides, the better.
Friend, if we can rule out the effects of process factors such as load fluctuations, as well as fluctuations in steam pressure and temperature. Well, then the problem with the speed control system is more serious. Does your speed control system use the wrong throttle? Are the secondary oil pressure and control oil pressure stable? First, check whether the indoor output voltage matches the secondary oil pressure What is the speed of the wrong throttle spool? Confirm these issues first. Then proceed with the analysis. According to you, the speed remained high while the speed control valve was constantly closed; suddenly the speed dropped. This phenomenon seems to indicate that there is a jam in the speed control system. You’ve mentioned not many conditions; it would be better to find more of them for a better analysis.
You can try cleaning the electro-hydraulic converter and the control oil circuit, as well as removing any salt or scale buildup in the speed control valve.
Fluctuations in the main steam valve? It’s the speed control valve, right? Isn’t the main steam valve only available in two positions: open and closed? But in any case, it seems that there is a problem with the speed control system; the control oil, electro-hydraulic converters, and hydraulic motors need to be checked one by one.