Regarding the issue of excessive vibration in vertical high-speed pumps
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Our unit has a vertical high-speed pump, whose structure is shown in the figure below. After startup, the vibration of the bearing housing fluctuated between 1.8–3.5 mm/s, accompanied by abnormal intermittent noises. The working medium is: propylene. Motor operating speed: 3000 rpm; input speed of the high-speed shaft: 11345 rpm. Among them: the number of teeth on the low-speed shaft is 125, while the number of teeth on the medium-speed shaft that matches it is 55. Medium-speed shaft: Number of teeth on the lower gear: 113; Number of teeth on the high-speed shaft gear that meshes with it: 67; The output high-speed shaft is equipped with an inducer wheel and an open impeller. The spectrum collected at the bearing housing is shown in the figure below: Please help analyze whether this fault is caused by imbalance of the drive wheel, imbalance of the high-speed shaft, or imbalance of the impeller
Possible process-related issues should be ruled out first, and then disassembly for inspection is required. Determine whether it is a process issue; try it with no load, that is, make the judgment under conditions that meet the minimum requirements. The structure is relatively complex and should be disassembled for inspection. During this inspection, a maintenance check should also be carried out. It is also necessary to check whether the oil needs to be replaced, as the bottom bearings in such structures are likely to get damaged when operating in an environment with a high concentration of oily impurities. For reference.
Is this running after maintenance, or is it the original pump? There are abnormal intermittent noises; I think it might be that a gear isn’t properly aligned or a certain component isn’t installed in the right place.
Was this first-order spectrum detected using a manual vibration meter?
Same problem; the cause has still not been found
There are intermittent abnormal noises; it is necessary to check whether propylene may be vaporizing Are the cold pump time and temperature within the acceptable range?
There is an issue with impeller balance due to the 1X height, but it is not a major problem. For amplitude fluctuations, it is necessary to monitor which frequency component is fluctuating before conducting an analysis. If there is 1X fluctuation, then the impeller may be loose or cracked. If it is a fluctuation in the meshing frequency, it may be caused by changes in flow rate, and no action is needed. If it is a fluctuation in the meshing frequency sideband, the gear may be damaged. If conditions permit, an endoscopy can be performed; if not, oil samples can be taken for testing.
It’s the Stadain high-speed pump; there’s probably some slight friction, so it needs to be taken apart for inspection.
2 is not the meshing frequency; it should be a harmonic of some frequency. Check the high-speed shaft bearing