Centrifugal pump vibration
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Centrifugal pump vibration Hello everyone, I have a rather troublesome pump here. I have been unable to solve the vibration problem for a long time. Please help me. Now tell me the situation: Model 80Y120 * 2. Medium diesel, outlet pressure 1.4MPA. Vibration suddenly appeared a year ago, reaching 12mm/s, or even higher, and the orifice ring and interstage sleeve were seriously worn. The work done for this purpose includes: In all centrifugal pump overhaul projects, all accessories have been updated and cut impellers, the entire pump has been reinstalled, and process pipelines have been cleaned. After multiple repairs, there has been no improvement. Generally, the vibration value is very small after the pump is opened after repairs, and is generally controlled at 2~3mm/s. But after two weeks, it reached 10 or above. The orifice ring and interstage sleeve were severely worn. I searched for process reasons and found no problems, and there was no problem when his backup pump was running. Most of the time, the backup pump was running for more than a year. Please help me find the reasons and solutions.
If you have a vibration measuring instrument, you can carefully measure the vibration displacement and speed values of bearings, footings, etc., as well as the frequency corresponding to the maximum value of vibration. Based on the frequency of vibration, you can determine what type of vibration it is. For example, unbalance, misalignment, loose feet, bearing failure, etc. If you don’t have a vibration measuring instrument, you need to carefully use a screwdriver to listen, or feel the vibration of the bearings, feet, and motor with your hands. ； Use your hands to feel the temperature rise at each bearing. Then, analyze the obtained data to find out the cause of the vibration.
Brother: After reading the replies from other guys, he was talking about general vibration diagnosis methods. It can be seen that he has some experience. However, the situation you mentioned does not require anything. Just looking at your description, I can find that the key is not vibration. Vibration is the consequence, maybe not the cause. The reason is as follows: You see: the vibration is very small after each maintenance, which proves that the cause of the vibration has been temporarily eliminated; the vibration becomes larger after two weeks, proving that the lesions have reappeared; so what you need to find are factors that can be eliminated after maintenance, but will appear again after a period of operation; First, you have to answer a question for yourself: Why does the mouth ring wear? The vibration is very small, if the gap is appropriate, and there are no hard particles in the process medium, how can it wear? The mouth ring is worn and the dynamic balance is destroyed. Of course, the vibration will increase. Is it that the dynamic and static parts are gradually becoming inconsistent, that is, the gap has changed? Or are there hard particles? Note: Even if the dynamic and static parts rub against each other, the vibration will not occur even if the vibration is too large. It is often wear that destroys the dynamic balance and causes vibration.
Don't look for problems with the bearings yet. Let’s first look for process problems. Does your pump often run out of time? Or is the filter often clogged or broken? Secondly, the standard of your pump is also very low. If it doesn't work, it is recommended to replace it with a pump with API version 8 or above.
The main reasons are:: 1. Troubleshooting operating problems, evacuation, cavitation, etc. ； 2. Ring wear is related to shaft runout. Check the bearing fit, clearance, channeling, etc. ； 3. Balance holes in impeller ； It definitely works! :lol :lol This post was last edited by pqj527 on 2008-3-1 11:32 ]
I agree with the opinion above, especially drilling balance holes should be effective.
Don’t impellers generally have balance holes? ! !