What should be noted during the turbine speed-up process?

During the speed-up process, care should be taken to quickly exceed the turbine’s critical speed. Also, pay attention to the system pressure and use backflow control to regulate the inlet pressure properly. Avoid accelerating too quickly to prevent impacts on other positions.

During the turbine acceleration process, when the speed rises above 1800 rpm, close monitoring of the lubricating oil pressure is necessary. If a decrease in pressure is detected, the turbine speed must be adjusted immediately; however, care must be taken to avoid staying at the turbine’s critical speed to prevent resonance-induced shutdown. It is important to get past this critical point of pressure change as soon as possible. Once the lubricating oil pressure returns to normal, the DC lubricating oil pump can be stopped, and acceleration can resume.

Agree with the above views: Personally, I believe that when increasing speed, one should pay attention to: 1. Quickly exceeding the critical speed. 2. Coordinate well with the reaction unit to prevent excessive acceleration, which could lead to negative pressure (causing a rapid drop in pressure in the settler); the backflow movement must also be properly controlled. 3. When compressing the rich gas and integrating it into the system, pay attention to the back pressure to strictly prevent surging. 4. For those with automatic speed control, it is essential to use it, as this will result in a smoother operation.

When increasing the speed, pay attention to the following: 1. Critical speed; 2. Impact on dry gas seals; 3. Speed of acceleration; 4. Valve opening degree; 5. Anti-surge operating point; 6. Be careful not to exceed the speed at high points

During the turbine acceleration process, the following points should be noted: 1. Ensure that the startup conditions are met; allow the startup light to come on, select either manual or automatic acceleration mode, control the speed and pressure, press the startup button and the acceleration button. The secondary oil pressure is used to adjust the opening of the control valve, thereby accelerating the turbine rotor to 1500 r/min. The turbine should then be warmed up at low speed for at least 25 minutes. 2. After the turbine is started, the steam seal extractor is put into operation; the steam pressure of the extractor is adjusted appropriately according to the speed increase of the unit, to ensure no steam leakage from the shaft seals at both ends of the turbine. 3. After the turbine is started, especially during each speed increase, perform the following checks: (1) Use a stethoscope to listen to whether the sounds at each bearing, on the casing, and around the coupling cover are normal. (2) The temperatures of each bearing, the oil pressure at each point, as well as shaft displacement, shaft vibration, and expansion values must be checked continuously and recorded on schedule. (3) Check at the oil return pipe gauge to see if the oil level and return oil temperature are normal. (4) Check whether the expansion washers of the cat claw bolts can move freely (free movement is normal). 5) Continue to increase the speed by pressing the speed-up button, either at a rate of 500 r/min or automatically up to 3000 r/min, and run the unit for 10 minutes while checking the condition of all its components. 6) Press the speed-up button to quickly exceed the first critical speed of 3455 r/min (for compressors) at a speed of 6000 r/min, or let it accelerate automatically to 4500 r/min, and run for 10 minutes. 7) Adjust the drain at the lowest point of the steam system to a lower level or turn it off as appropriate, depending on the hydrophobic conditions. 8) Continue to increase the speed from 500 r/min to 6089 r/min, run for 10–15 minutes, and check the condition of all parts of the unit. At this point, the speed regulator begins to operate. 9) Select the manual speed-up mode, and contact the control room and the boiler to connect the back pressure to the pipeline network at 1.0 Mpa. That is, gradually close the backpressure vent valve to increase the exhaust pressure step by step. When the turbine’s backpressure is slightly higher than the pressure in the pipeline network, slowly open the exhaust isolation valve until it is fully open. After that, close the vent valve as well as the drain valve on the exhaust pipe, and reduce the flow of water from the cylinder’s drain valve. During this switching process, it is important to maintain stable system pressure. After completion, choose between manual or automatic speed increase to continue raising the speed.

Low-speed warm-up: After draining water from the pipes, close the drain valve; once the conditions for starting up are met, use the quick-close assembly (1111) to open the quick-close valve (2301). At startup, turn the handle of the directional valve (1830, 1839); the directional valve (1839) generates start-up oil at 8 bar, while the directional valve (1830) connects the quick-shut oil to the return oil. Then, release the handle of the directional valve (1830) to create quick-shut oil at 8 bar. After 5 seconds, release the handle of the directional control valve (1839), and the oil level will start to drop slowly; at this point, the quick shut-off valve (2301) will open automatically. The travel switch (ZS587) on the quick-shut valve interlocks with WOODWARD505 (1310); WOODWARD505 is allowed to actuate the turbine only when the quick-shut valve is fully open. After starting, carry out a gradual low-speed warm-up, maintaining the rotational speed at around 600 revolutions per minute for 20 to 30 minutes. Note that the lubricating oil temperature should be between 35 and 40°C; it is not allowed to start the machine or increase its speed if the temperature is too low. 6.4.7.4 After checking and confirming that all parameters are normal, increase the speed according to the acceleration curve. Once the speed reaches 1000 rpm, maintain it for 10 minutes, check the operating parameters, listen to whether the sound of the turbine is normal, and ensure that there are no abnormalities in the temperatures and vibrations of the bearings. Speed increase: a. Once the unit is operating normally, the speed is increased by 200 revolutions per minute. b. Use the governor to control and adjust the steam valve in order to raise the speed to the rated value ； When increasing the speed, be careful to allow the machine’s temperature to rise gradually, following strictly the speed-up curve specified by the manufacturer, and avoid exceeding the critical speed too quickly. c. Units that are newly installed or started up for the first time after major repairs must undergo an overspeed protection test. The method is as follows: once the quick-shut valve is fully open, operate the WOODWARD505 regulator to increase the speed of the unit until the emergency safety device (three-out-of-two) sends a signal, causing the quick-shut valve to close. Once the speed drops below the minimum value, use the speed regulator to raise the speed back to the rated value ； d. Check whether it is running normally. If the oil temperature reaches 45°C, water should be supplied to the oil cooler. e. Adjust the steam seal extractor based on the steam leakage situation. Under load a. Increase to full load at an loading rate of about 100 kw/min. b. Check that the control system is operating properly, and that the secondary oil pressure, the opening degree of the hydraulic actuator, and the load are in proper balance with each other ； c. Check that the unit’s noise, vibration, axial displacement, temperatures of the thrust bearings and shaft bearings, as well as the rate of temperature increase of steam and metal, are all within normal ranges ； d. Pressure of the high-speed steam seal extraction pump and oil outlet temperature of the cold oil cooler, in a timely manner. Lubricating oil inlet pressure for each bearing stage. Close the drain valves everywhere. Use counter-rotating motion to control the inlet and outlet pressures of the compressor. The flare at the inlet should be slowly closed as appropriate. When increasing the speed, pay close attention to the inlet and outlet pressures of the compressor, and gradually raise the rotational speed to the rated value of 10,077 r/min as needed.

A few days ago I just saw a multiple-choice question about turbines and critical speed! That is: when reaching the critical speed, it is necessary to quickly exceed it – not slowly!

I’ve learned how to write; it’s been extremely beneficial. For a beginner like me, having experts explain things is really great treatment

1. During the turbine acceleration process, it is necessary to closely monitor the vibration of each bearing; if the vibration levels exceed the allowable limits, the turbine should be stopped immediately, and the maximum vibration value of the bearings at the critical speed should be recorded. 2. If the unit’s speed is near the critical speed, it should be increased to above the critical speed and then maintained at that level. Once the parameters stabilize within the allowable range, the unit continues to increase its speed.