Problem of oil mist being thrown along the axis on both sides of the centrifugal pump bearing housing
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We have a centrifugal pump on site; the medium used is washing oil at 160°C. There is an exhaust vent on the bearing housing, and this vent has been blocked since the equipment went into operation in 2005, yet the equipment continues to operate normally. After the temporary shutdown on March 24, 2016, oil mist was intermittently emitted from the shaft clearances on both sides of the bearing housing; the oil level in the oil cup dropped to zero within roughly 12 hours. Previously, this pump had been in continuous use for 2 months with no issues. Now that the exhaust hole has been opened, oil mist is no longer being emitted outward. I would appreciate it if everyone could help analyze the reason for this.
Your pump is likely a Sulzer pump; the bearing housing is cooled by air, and it is recommended to modify it to use water cooling.
The bearings inside the bearing housing heat up, causing the oil temperature to rise; the oil and gas then evaporate. If the exhaust holes are blocked, they can only escape through gaps. As long as the exhaust vent is opened, there will be no problem.
The upper ventilation plug should be open, but why was there no fuel mist in the first ten years?
1. The one on the upper part should be called a breathing cap; it needs to be open during operation in order to maintain normal pressure inside the bearing housing and prevent oil leakage due to positive pressure. It is generally used for labyrinth-sealed bearing covers. 2. The oil leakage you mentioned due to the blockage of the breathing cap is likely caused by the positive pressure in the bearing box resulting from the operation of the motor fan. Hope it’s useful to you
Well, this has also happened with the pumps we use; the lubricating oil sprays out directly from the fan in the bearing housing. The reason is that too much lubricant was added. 2. The oil slinger spins too fast.
At that time, the oil seal was new and could withstand a certain level of air pressure; over time, the oil seal started to leak
A few days ago, the pump was shut down for 10 hours for maintenance. After it was restarted, oil leakage began to occur on both sides of the bearing housing. I believe this is due to hot oil remaining inside the pump head, which causes heat to be transferred to the bearing housing through the shafts; at the same time, the pump head also has a heating effect on the bearing housing, resulting in continuous heating of the bearing housing during shutdown. This leads to the vaporization of oil, creating positive pressure. Once the pump starts operating again, the temperature of the bearings rises, further promoting oil vaporization. The exhaust vents become blocked, and the oil mist is discharged along with the gas under positive pressure inside the bearing housing. Previously, oil leakage did not occur because there was a small amount of oil and gas in the bearing housing, which was discharged through the small gaps in the labyrinth seal, allowing for a balance to be achieved. I invite all experts to offer their criticism and suggestions
There’s probably a problem with the bearing; oil mist will definitely cause the oil temperature to rise. It is recommended to measure the oil temperature.
This post was last edited by hy_0619 on 2016-4-6 at 11:10. The temperature inside the bearing box is high; your exhaust hole isn’t open, so the hot oil and gas can’t escape. They are forced out through the gap between the main shaft and the oil seal, and in this process the lubricating oil is also carried away. The main problems are: 1) the oil temperature inside the bearing box is high, 2) the exhaust hole isn’t open