Generator bearing and shaft neck after wear after the accident

Generator bearing and shaft neck abrasion accident after a 2019 - 12 - 05 the turbine for nac 50 mw ChunNing, inlet steam temperature of 535 degrees, 8 pressure. 83 mpa, the accident happened on January 26, for I am on February 2nd January 22 solstice during rest, now I know of the situation is briefly as follows, hope that we can analyze the cause of the accident, to discuss and improve together. Unit in 08 year on December 26, overhaul, after generator bearing oil ( Runtime oil, kerosene leakage besmear outside lime powder, apparently see leakage crack) , replace the bearing seat and a set of bearing or bearing, bearing of tubing interface grinding, internal use compressed air to blow, with minor wear and shaft neck using metallographic sandpaper. Overhaul after commissioning is good, but at run time, oil system of oil filter has many times due to the differential pressure big, clear separation, specific time on December 29, on January 1, January 3, January 5, on January 10th, January 15, 24 January ( Stop check found a mesh has copper wire cloth edge desoldering soldering, wire cloth off, the more 8 cm length) 。 At 1 PM on January 26, 2009, normal stop, stop turning on 27 January 11 o 'clock, found the exciter is faulty. Then, stop electric cart for manual turning. Site inspection found that the generator bearing after oil gear, small generators after the end cover and exciter fan place appear serious wear and tear, as many as 2 mm. After check related curve, the oil temperature in the process of turning gradually reduce, in an accident when oil temperature drop to 20 degrees; Generator bearing shell tile temperature after repeatedly appeared in the process of turning short time to heat up, but the temperature is not more than 50 degrees ( Tile temperature measuring point on the suction side from the split around 35 degrees) , after the generator bearing return oil temperature has been normal; DCS diskless current records, but turning operation is normal, never stopped. On January 31, 2009, stopped manually turning, after dismantling the generator bearing shell found journal and bearing shell are serious wear and tear, concrete can be seen below. The deepest journal wear up to 4 mm; Other bearing and shaft neck basic normal, only minor scratches. Check another feed at the bottom of the bearing sealing, found that the internal processing oil left by the borehole popcorn 2 slices, the thickness of 1 mm, an area of about 20 mm * 20 mm. There are other smaller wire or metal particles. Our preliminary analysis: 1, the unit in the overhaul and replacement bearing seat, bearing the garbage is not clean, Application of steam) , internal residual metal impurity, into the bearing shell junk slot, embedded in the sharply, and shaft neck grinding scraping each other. Create shaft neck have Nick, so normal running, often clean up oil screen, but when the normal operation of the scratch, the area is small, in order to establish the effect of oil film, in the process of downtime, steam for the rotor cooling, to steam rotor shaft neck direction, drive bearing and shaft neck more large areas of wear and tear, eventually happen now. 2, in the process of start-up, normal operation, stop, or, in the process of turning caused by short-term loss of pressure lubricating oil, the generator bearing after burn. After generator bearing at the end of the direction of oil supply, so the generator after the first short of bearing or bearing wear. （ Source: the coalification run dry quenching technology exchange learning platform)