Why is the secondary oil pressure of the turbine exceeding 0.45 MPa and reaching 0.5 MPa?
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Our plant’s turbine was shut down for 2 days to fix a minor issue with the compressor, during which time the oil pump kept running. Once the unit is started, everything seems to be normal, but when the load increases, the secondary oil pressure can exceed 0.45 MPa and reach 0.5 MPa; the actual opening degree of the control valve also exceeds 100% and reaches 125% (see figure). Excuse me, why is this? Are there any formulas for calculating the secondary oil pressure, as well as the input current of the electro-hydraulic converter?
There is a problem with this electro-hydraulic converter, and it needs to be dealt with by instrument maintenance personnel.
It has been in operation for half a year; the compressor was taken offline for minor maintenance, while no changes or repairs were made to the turbine.
It’s probably a problem with the electro-hydraulic converter. When the hydraulic actuator is at zero position, there are two small knobs – XO; these are usually set to 0.15 MPa. When the actuator reaches its full scale, XL should be set to 0.45 MPa. Instrument technicians should know this. I might have remembered the function of those small knobs incorrectly; please check relevant documentation.
Isn’t it necessary to perform valve calibration tests before driving? When the secondary oil pressure is 0.5, adjust the setting screw of the error valve, and then adjust the feedback; there should be no problems with the electro-hydraulic converter, and valve position limits also need to be taken into account
Isn’t it necessary to perform valve calibration tests before driving? When the secondary oil pressure is 0.5, adjust the setting screw of the error valve, and then adjust the feedback; there should be no problems with the electro-hydraulic converter, and valve position limits also need to be taken into account
It may be necessary to redo the static debugging.
Since the forum account is not linked to the WeChat account, two posts were accidentally created under the two separate accounts! But I’m not sure how to delete the post. Below are the reasons and solutions: Reason: During maintenance, in order to allow oil to return quickly, the return valve of the accumulator on the control oil line was opened; however, it was forgotten to be closed when the machine was started up, which caused a change in the oil pressure in the pipeline. (Deeper underlying reasons still need to be analyzed together.) Action taken: Close the return valve of the control oil accumulator, then lower the secondary oil pressure to 0.45, and adjust the opening degree of the steam valve to restore normal operation.
The cause and solutions have been found! But the deeper principles still need to be analyzed.