Analysis of Causes of Vibration Caused by Loose Rotor of Generator Rotor

Analysis of the Causes of Vibration Caused by Loose Rotors of Generator Rotors Bao Cheng, an overview of the Hubei Ezhou Power Plant Project is the first foreign-invested power infrastructure project in Hubei Province with an installed capacity of 2,300 rivers. The unit shaft is made up of TCDF33.5 steam turbine produced by Hitachi, Japan, QFSF300220 generator produced by China Dongfang Electric Machinery Co., Ltd., and Dingji 16704 exciter and auxiliary exciter are combined. This unit combination is still in Hubei Province. The first case. The whole shaft system of the unit consists of 5 stages of rotors, 10 support bearings and 1 separate thrust bearing. There are 4 couplings in the shaft system. The generator rotor and the exciter rotor are connected by the wave joint coupling. The other 3 Each coupling is a rigid coupling, and its arrangement is 1. The thrust bearing is located in the No. 2 bearing housing.

The low-voltage generator exciter auxiliary exciter corrugated simple coupling is the largest shaft vibration for 38 units, and the vibration is better. On the 23rd of 1998, the accident of the air-side seal oil pump accident of Unit 1 occurred. At that time, the standby oil pump was linked, and the temperature of the No. 58 bearing tungsten gold was not detected. The oil return temperature of each bearing was normal, but the shaft vibration of the No. 58 bearing was Different degrees of change, especially the shaft vibration value of the No. 7 bearing bush increased significantly, and its value increased from 26μm to 79μm. On December 14th, when the unit started the critical speed, the No. 7 bearing nut No. 567 bearing bush journal has Different degrees of damage, No. 5 lower tile has about 180, 2, long and wide scratches, No. 6 tile damage is lighter, about 45 tungsten gold on the left side of No. 7 lower tile partially fell off, its area is about 57, 35 plus, 2, and the bright belt of the upper and lower tiles and the journal are ground, which is caused by the partial fragments of the tungsten gold. The bearing of the 8th is normal, and the generator sealing tile has only slight scratches.

1 Fault handling and vibration cause analysis After the on-site repair of No. 7 bearing bush and the overhaul and reassembly of No. 58 bearing bushing, in view of the vibration condition of the unit and the inspection condition of No. 58 bearing bush, the supervisor believes that the turning of the tile inspection No. 7 There is a phenomenon of hook gold shedding, but it cannot be said that the large vibration of the No. 7 tile shaft is caused by this, because the 7th tile tungsten gold falling off position is about 45. on the left side of the lower tile, and is not in the bearing surface of the journal and the bearing contact 60. On the above, the analysis of the state of tungsten gold shedding may be due to the potential quality of the bearing bush during the casting process in the manufacturing plant, so the crew test showed more than a year. First, fluctuations and changes in generator seal oil pressure and temperature will only directly affect the generator rotor. The effect on the 7th watt shaft vibration is only indirect. After the seal oil pressure and temperature are stable, the generator rotor 5 is 6 The vibration of the bearing bush can basically return to the original stable condition, that is, the oil temperature corresponds to a vibration value, while the shaft vibration of the 7th watt is high, which also indicates that the fluctuation and change of the sealing oil pressure and temperature are not directly affecting the 7th watt. There was no similar vibration during the increase of the shaft vibration. From the above point analysis, it can be preliminarily determined that the real cause of the large vibration of the 7th wattage axis has not been found, so it is not rushed to start again, and the wheel sway of the generator rotor and the excitation rotor is detected.

Check the generator rotor and the exciter rotor to find the wheel yaw value of 0.4, far exceeding the original value of the installation. The disassembly of the coupling is improved. It is found that the rotor end of the generator has looseness on the wheel flange and is fixed. The rotor end of the generator is 180 degrees apart from the wheel, broken, and the section is polished. Two screws are partially broken, and three broken bolts are continuously arranged. 2 locating pins, one has been broken into segments, and the other locating pin and pin hole are severely deformed. The pin hole is from 25.00 in the original to the elliptical hole in the middle 26.80.

According to the preliminary analysis of the bolt and pin fracture phenomenon, it can be seen that the tightening force of the fixed flange flange bolt and the pin is insufficient and the tightening force is not uniform, that is, the bolt tightening torque is insufficient. The friction between the two pairs of wheels is insufficient, and when the bolt is subjected to a variable load, the stress is concentrated at the root of the bolt, and the unit is operated for a long time, causing fatigue fracture.

After comprehensively checking the data of the two pairs of wheels of the corrugated section coupling, the generator rotor end-to-wheel measurement shows that the gap between the generator rotor and the counter-wheel flange is 0.34, according to the manufacturer's rotor. Assembly requirement 4, the design range of the joint is 0.050.28, the matching clearance is too large, and the measured fit clearance is 0.06 larger than the designed maximum gap. The pair of wheels are assembled in the manufacturer and no on-site inspection is required. When the tightening force of the rotor-to-wheel flange of the generator rotor is insufficient and the tightening force of each bolt is uneven, the clearance between the generator rotor and the flange of the opposite wheel flange is too large, which is the cause of the fatigue fracture of the bolt and the pin.

The inspection and reassembly of the coupling components is essential, and each process and process quality is related to the vibration of the unit shafting.

The first is to repair and reassemble the rotor end of the generator rotor. All the 8 bolts are replaced by the manufacturer, and each bolt hole is cleaned by wire tapping to facilitate the bolt and the tightening force. The deformed locating pin hole is made by the on-site reaming pin. When the pin hole is changed to the flange of the wheel, it is recommended that the bolt tightening force is insufficient for the manufacturer. The measured value of the round scoop is 0.12, the value of the exciter rotor to the side of the wheel is 3, and the design value of the manufacturer is 2!1. To ensure the joint quality of the coupling, it is required to bias the two pairs of scissor After the treatment of two pairs of rounds of scooping was passed, the data of the scoring partial acceptance were 1, 1 and 0.0075 mm, respectively, which met the excellent standard. Finally, the generator rotor and the exciter rotor coupling pair wheel are connected, and the center record is 5.

Note that the rotor is rotated counterclockwise 3 and the precautions and recommendations for the same type of unit are repaired. Unit 1 is started, and the 7th shaft vibration is basically restored to its original state. On January 7, 1999, the unit belt At 305 elbow load, the 7th wattage shaft vibration is 41.33. During the 14-day full load continuous trial operation, the shaft vibration of the entire shafting system is stable within 5, 4, and reaches an excellent level. The unit has been running so far, it is safe and stable, and it is stable and full.

The generator rotor and the counter wheel flange of the unit are assembled by the manufacturer according to the design, assembled in the factory and shipped to the site. The manufacturer does not make any requirements for on-site installation. For the same type of structural unit, in order to prevent the occurrence of potential quality accidents, it is recommended to carefully check the bolts of the generator rotor and the wheel flange and the wheel itself. First, check whether the generator rotor excitation is loose on the wheel flange. If the wheel flange is loose, the flange of the generator should be disassembled to check the matching clearance between the generator rotor and the flange of the wheel flange. Factory design and power industry standard inspection requirements.

First, use a torque wrench to check whether the tightening force of each bolt is in place, whether it is uniform, and whether the torque meets the design requirements of the manufacturer. First, check if the positioning pin is in place. First, strictly check whether the bias and sway of the two pairs of scoops meet the requirements of the manufacturer's design and the power industry standard inspection. The bias value of the wheel scoop is preferably controlled within 0.01, which is advantageous for the fitting of the shape of the ¢26.80mm to the ¢27mm. The quality of the joint in the reloading wheel.

Li Guoli