The turbine speed suddenly dropped from 8000 r/min to 7000 r/min, and after some time it returned to normal. What could be the reason?
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The steam pressure is normal, with no fluctuations； The lubricating oil pressure is also normal.
First, check if there is a problem with the tachometer, and then examine the speed control mechanism.
This post was last edited by SAN*NGR428 on 2018-9-16 08:40. Does the steam enthalpy mean that there is a change in superheat? Has the vacuum level fluctuated? Is there intermediate extraction steam? Are there any fluctuations in the pressure and flow rate at the exhaust port? Did the opening of the speed control valve change when the rotation speed fluctuated? Has the oil pressure fluctuation been adjusted? There are generally at least 5 to 6 speed probes. On the DCS or CCS/ITCC screens, two or three values related to the speed regulator can be seen; there is also one local speed gauge or a gauge for detecting zero speed. Additionally, there are 3 probes that feed data into the electronic overspeed protection system. It’s possible to check the protective devices in the cabinet to see if there are any changes
In a back-pressure steam turbine, changes in the opening degree of the control valve result in changes in the control oil pressure as well
Check the speed tracking parameters to see if there are any changes
If there is a change in the opening degree of the control valve, it indicates that there are indeed significant fluctuations in the rotational speed. It’s necessary to determine whether the decrease in rotational speed is due to an increased opening degree of the control valve After the rotation speed is restored, does the control valve remain at its expanded position or return to its original opening degree? The back pressure generally does not experience large fluctuations; if the temperature of the incoming steam decreases, it is likely a problem with the control valve.
It is possible that the adjustment of the steam valve does not correspond to the rotational speed; this leads to a decrease in speed. By increasing the opening degree of the steam valve, the speed gradually returns to the level corresponding to that opening degree
Excluding changes in steam parameters, check whether the oil pressure control valve at the lubricating oil station is operating unstably It is also necessary to verify whether the secondary oil pressure matches the previous parameters
If the turbine is the driving machine, then the operating condition of the compressor also needs to be considered
I think there might be a problem with your oil motor! It might be that the spring for the throttle is faulty! It’s also possible that the piston inside the cylinder is stuck! It’s a good chance to take a look! The recommendation to suspend operations for maintenance is aimed at carrying out these tasks
Are there any fluctuations in the pressure of the low-pressure steam pipeline network?