Issues regarding the mechanical seal of hot oil pumps
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The temperature of the hot oil in our company is between 270 and 280 degrees; we use hot oil pumps manufactured by Dalian Huaneng Acid-Resistant Pump Factory, which feature mechanical seals with jackets. The newly replaced mechanical seal pump operated without problems for 1 day, but after 1 week it started to leak slightly, and the problem worsened over time; there was no other choice but to replace it again, which had to be done quite frequently. At first, it was suspected that the pump base was not aligned; after trying to align it, the problem persisted. I would appreciate it if fellow enthusiasts could discuss ways to resolve this issue.
First, you need to check the model of your machine seal and the material used for the O-ring. The leakage situation needs to be clarified; based on what you said, it should be internal leakage. Also, it’s necessary to clarify whether there is leakage – is it dripping, or something else?
The Plan21+62 option can be considered. Plan62 uses 140-degree heavy diesel or wax oil for quenching.
Agree with what was said on the 2nd floor; it’s necessary to determine whether the leakage is between the rotating and stationary rings or due to a faulty O-ring, as the solutions for these two situations are different.
At first it was a drip, then it turned into a steady stream. It seems that the moving and stationary rings are exposed; it’s still in operation and there is no backup pump, so we can only stop operations and conduct a thorough inspection later. The mechanical seal is pressed with steam.
Reply to 3# sysd8203: There is no emergency cooling for the mechanical seal here; jacket steam cooling is used, at around 140°. It doesn’t work well.
At such high temperatures, it’s better to seal them in pairs – safety is important. By the way, with such high temperatures, it’s definitely welding the metal bellows for sealing; so there’s no need to bring up the issue of O-rings.
Reply to 6# happyboybin: You can get in touch with the manufacturer for sarcasm. Ask them to come up with a better plan.
For temperatures below 300 degrees, metal bellows cloned from Dandong should work well in most cases; the seals used in our factory continue to perform well even when cold water is in use.
We have been using imported KSB pumps, but be careful not to buy fake ones. I think the problem lies in the pipeline stress; if the original poster has time, they can send some photos of the pipeline connections so that I can help diagnose the issue. One of our engineers made a mistake in the past, which caused several pumps to break down; it took some time to identify the problem, and once it was fixed, no further failures occurred. (Note: The pumping station has a total of 6 hot oil pumps)
What was said upstairs is correct – for the oil wave expansion joint at the pump inlet, since the medium temperature increases gradually, there should be no issues with sudden cooling or extreme heating. I’ll send photos to those who mentioned it upstairs later. The pump shaft is also vibrating severely. I’m not a mechanical engineer and don’t know much about pumps; I hope everyone can offer some guidance.