What causes intermittent evacuation in high-temperature pumps?
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There is a medium at 200 degrees at the bottom of the tower where the pump is located; the pump uses double-end face mechanical seals in a back-to-back sealing configuration, with metal bellows serving as the auxiliary seals. Previously, the mechanical seals leaked, causing diesel to flow into the pump, which resulted in vacuum conditions in the pump. It is suspected that the high temperature of the flushing oil caused it to vaporize, leading to the vacuum condition. Today, both mechanical seals in the pump were replaced, and no leaks were detected during testing; however, vacuum conditions still occur. The normal outlet pressure is 1.25 MPa, but after about 10 minutes, the pressure drops to 1.0 MPa. Yet, when the outlet valve is opened, the pressure returns to normal levels. The exhaust from the pump is also quite thorough. What could be the reason for this? Please, experts, help analyze it
The medium transported by our high-temperature pumps is at around 300 degrees Celsius; frequently, the outlet pressure does not rise or there is no flow – is this caused by cavitation?
Our pumps have not encountered this issue before; a few days ago there was internal leakage in the mechanical seal, and it was suspected that diesel used for flushing leaked into the pump and turned into bubbles due to the high temperature. Today the mechanical seal was replaced and tests were conducted, showing no leakage, but the problem of vacuum formation still persists. I’m not sure what the cause is; I hope someone with more experience can offer some guidance