Regarding the issue of high vibration when the new LNG pump is in operation
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The pump had normal vibration levels during laboratory tests at the time of manufacture. However, during testing in the LNG storage tank (with all valves set to reflux mode), it was observed that the vibration levels increased sharply once the LNG level in the pump tank reached its maximum. Moreover, once the outlet exhaust valve was closed, the vibration levels rose even further. Throughout this process, both the pump’s current level and the outlet pressure remained within normal ranges. Could anyone please explain what could be the cause of this phenomenon?
Seeing this description, I have a question: was the exhaust valve not closed when the pump was started to feed material?
When starting the pump, the exhaust valve is open to remove the gas from the outlet pipeline, allowing the pump tank to be filled with liquid more quickly and also preventing cavitation from occurring. Within a certain period after startup, the exhaust valve will close automatically, and excessive vibration occurs at this time.
When starting the pump, the exhaust valve is open to remove the gas from the outlet pipeline, allowing the pump tank to be filled with liquid more quickly and also preventing cavitation from occurring. Within a certain period after startup, the exhaust valve will close automatically, and excessive vibration occurs at this time.
If this happens during debugging, check how high the tank level is Is it caused by the low liquid level in the storage tank? Also, does this vibration persist from the moment it starts until the pump stops, or does it occur periodically – for example, there are a few seconds of vibration followed by a few seconds of stability, after which vibration occurs again and then stability once more? I suspect it’s a problem with the operating conditions during debugging, rather than an issue with the pump itself.
Hello, the liquid level in the tank was much higher than the net positive suction head required by the pump, and high vibration persisted until the pump was stopped (for about 15 minutes). Regarding the process pipelines, both the exhaust pipes and return pipes have been checked, and there are no issues with blockages.
Check whether the pre-cooling meets the requirements; manually open the exhaust valve. If the condition improves, it is likely cavitation.
The pump body has not cooled down completely, and the LNG vaporizes upon entering the pump
Take a look at how high the liquid level in the tank is Is it caused by the low liquid level in the storage tank? Also, does this vibration persist from the moment it starts until the pump stops, or does it occur periodically – for example, there are a few seconds of vibration followed by a few seconds of stability, after which vibration occurs again and then stability once more? I guess it’s a problem with the operating conditions during debugging, rather than an issue with the pump itself
It might be caused by the gas-liquid two-phase mixture; will it stabilize after vibrating for a while?