Discussion and improvement of the sealing of the bearing device of boiler induced draft fan
The defects of the original seal and lubrication and the analysis of the cavity ring on the bearing side cover and the bearing cover (seat) of the fan constitute an approximate straight-through labyrinth seal structure. Although there is no pressure difference between the bearing oil inside and outside, the bearing rolling element With oil agitation, the oil flow has both a splash to the seal (more often when the oil level is higher) and a tendency to migrate outward in the axial direction. Due to the difference in the dynamic energy consumption of the straight-through labyrinth, the sealing is mainly ensured by reducing the gap and increasing the number of cavities (rings). There are only two (cavity) rings on the bearing side cover of the device, and the gap has been increased from 01400150mm to 21503100mm due to wear, the seal has completely failed, and the oil leaks over the chamber with the oil return hole because there is no retreat. It can only continue to the outside, leaving a contact seal (felt) also leaks due to leakage and severe wear after oil saturation, resulting in shorter maintenance intervals or increased leakage.
Through calculation and analysis, it is considered that the lubrication method is improper. Therefore, the way the original design lubricant is lubricated should be restored, and the sealing system must be modified. Seal modification situation In 1997, the lubrication of the bearing of a boiler induced draft fan was restored to the oil bath mode. Only two improvements were made, that is, inserting a oil baffle (made of white iron) on the side of the bearing, close to the inside of the bearing side cover. A rubber ring is added to the gap seal to play a certain role. The inner oil block made of white iron (the inner diameter is slightly larger than the outer diameter of the nut, ensuring that the static and dynamic parts are not rubbed, and the bottom is cut off below the oil level so that the oil in the oil chamber and the bearing convect and mix with each other) is bolted to the bearing side. The cover or the bearing cover (seat) acts to block the oil flow from splashing outward (oil chamber).
After the transformation of the trial effect, the fan has undergone 2 trial runs (times above 10h), no leakage, and the sealing effect is unexpectedly good. Operation The fan has been put into use since the transformation. It has passed the test of a long period (100d). It runs smoothly, the sound is normal, the oil level remains unchanged, and even the traces of leakage or leakage are not seen. The problem of the production equipment is to ensure the clean and civilized scene. The outer oil block (PTFE) is almost free of wear and other parts are less likely to wear. The change of bearing lubrication method should be treated with caution. Seeking truth from facts and specific analysis are the secrets of successful transformation. It is not excluded that there are other successful experiences in changing the lubrication method of bearings, including the use of some new lubricating materials and anti-wear agents (such as iron tyrants). The purpose of this paper is to introduce a simple method of sealing modification, suitable for similar Bearing lubrication and sealing problems.
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