Reasons for the issue in the relationship between secondary oil pressure and the stroke of the oil-driven motor
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During the restart of the steam turbine compressor after cleaning the filter, the use of the quick-shut valve resulted in the failure to establish the quick-shut oil pressure due to the too rapid pressure release of the start-up oil; this also caused the secondary oil pressure to release repeatedly. Could this lead to problems in the relationship between the secondary oil pressure and the stroke of the oil-driven mechanism (that is, the secondary oil pressure of 0.15–0.45 MPa no longer corresponds to the opening degree of the main steam valve)? As a result, equipment technicians were called in to conduct further static calibration tests. Does anyone here know about this?
No. Establishing a quick-shut oil pressure is a control system ； The establishment of secondary oil pressure is a system in which an electro-hydraulic converter converts electrical signals (4–20 mA current) into oil pressure signals (0.15–0.45 MPa). Since it is already a complete system, there is no need for re-tuning.
The key issue is that there was a problem on site, for no apparent reason? At least when the starting oil pressure is established, there is also secondary oil pressure; when the starting oil pressure is reduced, the secondary oil pressure fluctuates as well. What are other reasons that can cause a mismatch in secondary oil pressure?
As the quick-shut oil is generated, it flows directly into the electro-hydraulic converter, which then outputs secondary oil； If the fluctuations between the establishment and pressure release of the quick-shut oil inevitably affect the secondary oil
The pressure release for starting oil at the site was done too quickly, which caused the pressure required for rapid shutdown to be released as well; as a result, the rapid shutdown valve did not open. This happened twice. The same is true for the secondary oil pressure; then problems arise. Is there a causal relationship between the two?
It has nothing to do with this; simply re-perform the valve calibration. Due to dirty oil and prolonged operation, it is necessary to carry out valve calibration tests before shutting down and restarting the system
The secondary oil pressure is based on the quick-shut oil; it is the quick-shut oil that enables the generation of the starting oil. The quick-shut oil’s role is merely to open up the solenoid valves and other components in the oil circuit. In reality, the electrical signals are converted into pressure in the power oil, that is, the oil pressure at the pump outlet is used for regulation. So there is no significant impact. However, as a precaution, it’s best to test the range of motion of the speed control valve to be absolutely sure. If the adjustment nut becomes loose, it may not function properly, and opening the quick-shut valve could cause the speed control valve to reach speeds of several thousand revolutions per minute.