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Because of the accident to bearing damage, completes the bearing detection is of great urgency - bearing knowledge

by:Waxing     2020-06-02
The kansai electric power company to hainan power plant the kansai electric power company power plant capacity of 600 mw # 3 machine in June 1972 destructive accidents occurred in trial operation. The accident happened in units great vibration within a very short time after that happened. Usually, the increase of steam turbine generator vibration for many reasons, but in such a short time so big vibration, # 3 # 11 bearing ( Exciter) This time the cause of the accident damage. Because of # 11 bearing bearing cover and bearing assembly quality is not very good, commissioning, the speed drop shaft vibration particularly big, wear and tear of the bolt screw thread; The overspeed test ( Speed up to 3850 r/min) , # 11 bearing the axial vibration of a sudden increase, the bearing cover fixed bolt out, busbar loss; On the bearing and oil baffle ring after fly out, can't offer lower bearing lubricating oil, # 11 a bearing. At this time, the oil film damping is reduced, resulting in a decline in shaft critical speed, close to the actual speed ( 3850 r / min) And cause resonance, the resonance immediately prompted a huge vibration exciter shaft ( See the figure) 。 In a great vibration of the unit after a very short period of time, more section of shaft fracture, parts and components, and cause a fire, especially big accident. Figure 3 is # 9 ~ # 10 generator bearing structure, figure 4 to # 11 bearing structure. With the increase of generator capacity and the growth of the shaft, the vibration of steam turbine generator problem will become even more important, so the structure, installation and commissioning should be particularly pay attention to all aspects. The accident lesson, for bearing installation and fixed must adopt a full consideration of the problems of vibration installation technological process. In addition, we should balance adjustment method of improvement including exciter generator of the whole shafting vibration calculation method of inspection. Heilongjiang big bending axis accident of a certain power plant in heilongjiang province motor maintenance staff of a certain power plant in November 1993 # 2 machine processing exciter commutation carbon brush a blaze defect, due process, technical level is not high, cause the ring of fire, lead to # 2 generator field loss, active load swing sharply, speed regulating valve is out of control, buried under the ruin for the accident. When electrical run attendant for control of generator out-of-step, when using a synchronizer # 2 machine active load reduction, has adjusted is invalid, so break out the magnetic switch, column of the machine. After solution column # 2 machine, speed regulation valve cannot close, not only maintain the unit idle, and rotational speed rising rapidly, causing critical protector action, the main valve closed automatically. Defects, due to the main valve automatically the jamming are not locked, unit caused by overspeed accident: the first is at the end of the turbine triple blade fracture damage, breakdown first exploded in the low pressure cylinder, and strong vibration unit, string of shaft, shaft stability damage, and damage the generator seal. Followed by the hydrogen spillover second explosion happened and caught fire, and turbine turbine oil ignition and part of the cable; , then further instability of shafting, destroy all bearings, twisting spindle, make each activity turbo-generator set some serious touch grinding, impact, seriously damage the unit. Close the main steam pipe after electric main gate and total valve, just completely cut off the admission, rotor rotational power lost and stop, the process time is short. Supercritical unit in one power plant in jiangsu shaft neck injury in jiangsu province with 2 units of 600 mw supercritical unit. On March 3, 2006 C level maintenance smoke generator rotor is found that the generator excitation end bearing severe wear and shaft neck also serious wear and tear. Opened on March 8 # 8 bearing shell tiles, wazhou found # 8 axis neck middle severe wear, wear occurs in middle position, wazhou # 8 shaft neck axial period of about 420 mm long axis, the wear depth ( Radius direction) 0. 1毫米~ 0。 80毫米。 The deepest about 1. 0mm。 Turned out after # 8 on the bearing shell tile, tile on a slight abrade, # 8 journal is severely scratched, article 17 of the scar, the largest scar about 2 mm wide, deep about LMM, the scar is circular shape, from the middle to the sides, in turn, gradually densely distributed in # 8 journal. Dig out # 8 bearing bush found that after the second half of the tile generator end basic jacking oil sac by wear or by wear tungsten gold filled, heavily damaged motor end surface of tungsten gold, tungsten gold and steam end surface has serious phenomenon, hair, hair attached to a large number of fine wire. Mesh serious breakage caused a large number of fine wire into the lubricating oil system, a large number of fine mesh wire as lubricating oil pours into between shaft and bush. Destruction of the oil film between the shaft and tile, exacerbated by the friction between the shaft and tile. Accident occurs, the mother pipe jacking oil pressure has fallen to 9 mpa, 12 mpa is lower than the design value. Under the pressure, # 8 journal has not completely jacking. As mother pipe jacking oil pressure drop, which leads to the shaft and bearing clearance is reduced, while the low pressure cylinder on both sides of the bearings with bearing affected by the condenser vacuum and single side bending, thus easy cause bearing one tile burning.
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