The screw compressor works fine under no-load conditions after maintenance, but why is there significant vibration during load testing?
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We are performing maintenance on a screw compressor on-site. After the maintenance, there are no issues at no-load conditions, but there is significant vibration during load testing – what could be the reason?
Check whether there are any issues with the control system, as well as the readings on the instruments to see if there is an overload. I’m not sure what the equipment looks like; this is for reference only.
This phenomenon is difficult to find. Because during reinstallation, issues such as the meshing clearance of the transmission mechanism and the bearing alignment of the rotor arise; at this stage, it is only possible to look for problems in the instrumentation and control system first. If those issues cannot be resolved, the component will still need to be disassembled and reinstalled. During reinstallation, mutual confirmation is necessary, and records must be kept for archiving. For reference.
If it worked fine before the maintenance but started to have problems after, then there must be an issue with the assembly details
What is the coaxiality? Is there a problem with the coupling? How is the quality of the oil? Are the anchor bolts properly tightened? Is there any liquid inflow after applying load? Vibration is also high when liquid is flowing in. Is the current high? Can the shaft be rotated easily before startup?
Whether the outlet valve opens successfully or if the outlet pipeline is blocked, causing the check valve to open and close frequently and resulting in surge
The gear mesh clearance is too small, the clearance between the outer ring of the bearing and the gland does not meet the requirements, or the rotor runout is excessive.
How was the turning of the shaft before startup? Was there this issue before maintenance?
See if the load can be adjusted – reduce it a bit first to see if there’s any change, or set the outlet pressure lower, and then gradually increase the load to observe the vibration levels
I’m very grateful for everyone’s replies; thanks for participating in the discussion. Last year, debris entered this unit, causing friction between the screw and the housing; after it was shut down for maintenance, it operated for a few months before experiencing excessive vibration. During this latest maintenance session, the meshing clearance and alignment were adjusted as required. The operation is normal under no-load conditions, and there should be no issues with operation; loading should be increased gradually as per the specifications. However, excessive vibration persists. The manufacturer has also arrived, and it has been decided to send the unit back to the factory for repair. We will keep you informed of any further developments.