Vibration in the inlet pipeline of multi-stage centrifugal pumps
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We have three multi-stage centrifugal pumps from Shanghai Kaiquan used as feed pumps for the waste heat boiler, model: DG25-50*12. It is mainly used to supply water to the boiler; the deionized water flows from the deaerator to the feed water pump. The pressure in the deaerator is 0.12 Mpa, and the temperature is 100–104°C. Now, when all three feed water pumps are started, there is significant vibration in the inlet pipes, as well as large fluctuations in the outlet pressure gauge; however, the vibration at the outlet is not significant. We began to assess cavitation by lowering the temperature of the deaerator water to 83°C; however, the feed pump still experienced significant vibration in its inlet pipeline. It was later suspected that the inlet pipeline of the feed water pump was blocked; the main valve of the pipeline has been replaced with a new one, and opening the manhole of the deaerator for inspection revealed no issues. I urgently need the help of all experts.
We have the same problem: the export pressure fluctuates greatly, and the check valve makes a noise every few minutes. It was working fine before.
Let’s make the inlet pipe larger and see. We did the same thing when installing the water pump before; after making the inlet larger, it worked fine.
Based on your description, installation issues as well as mechanical problems with the inlet bearings or alignment can be ruled out. It is recommended to use methods such as increasing back pressure, raising the inlet flow rate, and increasing the minimum reflux volume
It is still necessary to look for the cause within the scope of process control; first, it is essential to verify whether all process control parameters match the design parameters.
Is the inlet filter clogged?
Still looking for the problem at the entrance – is there insufficient traffic there?
Imported as DN125, exported as DN65. It should be a problem with the pipeline; we have been using this pipeline since 2011. The conditions I mentioned above appeared suddenly.
The problematic feed water pumps have all been in use for almost a year at the shortest; if there had been issues, they should have appeared long ago. Are you helping me do some research?
There was no change in the process; it was just that the above situation appeared suddenly
The inlet filter has been checked and is not clogged.