The negative pressure during the startup of a centrifugal turbine compressor causes an increase in bearing temperature and vibration
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Dear teachers, I have a question. Our company has a centrifugal turbine compressor with 4 stages of compression. During startup, it was started without first contacting the control room; the control room failed to open the inlet valve for one and a half minutes (this refers to the valve in the gas supply line, not the inlet guide vanes), which resulted in a negative pressure at the inlet of 0.8 MPa. Once the inlet valve was opened, the vibration level across the 4 stages increased by 4 um, and the shaft temperature rose by 10°C. Moreover, the variations in temperature and vibration as a function of load were much greater than before. The bearings used are tilting-pad type bearings. Currently, it is operating at reduced load. After switching to this mode, the bearing temperature and vibration levels remain stable, with no significant increases or decreases observed. Could the teachers help analyze the possible reasons briefly? Could it be caused by that area? What should be done or checked next? Thank you for the guidance.
I suggest you stop the vehicle and check the bearings
The compressor is surging. It is best to indicate what the original vibration level was, what the original oil temperature was, and by how much the vibration and oil temperature increased when the load rose. This will make it possible to determine whether to operate at reduced load or to continue operating at full load. Has there been any change in the temperature of the thrust bearing?
May I ask about the changes in shaft runout, the changes in thrust bearing temperature, and the changes in lubricant consumption? It is recommended to check the bearing for wear on the thrust pads. If the compressor lubricant is being consumed in large amounts, it means the seal has also worn out. Judging from your description, the sealing should be fine.
If the inlet valve of the centrifugal compressor is not opened, it will not cause vibration in the bearings; it is recommended that you still check the bearings.
The oil temperature is automatically controlled by a temperature control valve, at around 50 degrees. The vibration level at grade 4 has increased from 11 to 15. The bearing temperature has risen from 97 to 108.
Hello, I hadn’t paid attention to the sealing aspect before; it’s important to know what level of sealing is used, and the exhaust gas should be routed to a pipe for release. I didn’t pay much attention to the amount of gas before. I would like to ask, what symptoms will occur if the seal is damaged?
Hello, I hadn’t paid attention to the sealing aspect before; it’s important to know what level of sealing is used, and the exhaust gas should be routed to a pipe for release. I didn’t pay much attention to the amount of gas before. I would like to ask, what symptoms will occur if the seal is damaged?
It has little to do with sealing; I work in the compressor industry, and the unit probably uses carbon ring seals! I’m not entirely sure about this. If the mechanical seal is worn, it can cause air leakage. A temperature increase in the bearing oil from 97 to 108 definitely indicates that there is damage to the bearing; changes in temperature will also lead to vibrations. It is recommended to stop the machine for inspection. Continuing to operate it may cause damage to the rotor, which could ultimately result in the impeller rubbing against the ring, leading to the destruction of the rotor. If you need my help, I’m available.