Fault Analysis and Treatment of Vibration and Displacement of Air Compressor Shaft

4Experience Wenyu t air compressor shaft vibration displacement fault analysis and treatment Zhang Jingtao, Li Hongbo, Wang Feng (Jigang Group Co., Ltd. Maintenance Engineering Company, Jinan 250101, Shandong, China) caused by the edge curling of the blade. Disassemble the first and second rotors by disintegration, and return to the factory to repair the second impeller blades to do the dynamic balance test, thus solving the fault of the secondary pinion shaft vibration displacement.

1刖m Jigang Gas Company currently has 6 sets of oxygen generators with an oxygen production capacity of 135,000 m%. In November 2012, the air compressor station TAE-100M/30 type COOPER turbine air compressor (hereinafter referred to as air compressor) occurred the secondary pinion shaft vibration displacement, protection control interlocking shutdown failure, endangering the stability of the compressed air system. run. After careful analysis, the cause of the fault was found, and corresponding measures were taken to eliminate the large vibration displacement of the secondary shaft, and the air compressor was restored to stable operation.

2 Fault analysis and processing 2.1 Equipment overview and failure phenomenon The compressor, motor and oil system of Jinan Steel Company are located on the same rigid base, and the intercooler is arranged on both sides of the box. Three-stage compression, the driving gear shaft drives two driven gear shafts for speed increasing operation, the first and second impellers are mounted on the same gear shaft, and the three-stage impeller and balance disc are mounted on one gear shaft. The oil supply system is mainly composed of main oil pump, auxiliary oil pump, oil cooler, oil filter and oil pipeline auxiliary parts, etc. The main oil pump is a screw pump, and the auxiliary oil pump is a gear pump. The oil station is equipped with a 4.5kW electric heater. The compressor is equipped with a three-stage shaft vibration displacement on-line detection device, which adopts constant pressure control mode.

On November 24, 2012, the post inspectors found that the secondary shaft vibration displacement of the air compressor was large and the protection control was interlocked. From the equipment operation fault alarm information, the vibration displacement measurement of the secondary shaft when the air compressor is stopped is 56|JLm, which is greater than the protection control interlock value 48|JLm. The motor and electrical system are inspected, no abnormality is found, and it is decided again. Start the air compressor test. After the air compressor is started, it runs for 15 minutes without load. The on-line detection values ​​of the shaft vibration displacement of each stage are normal, but the interlocking stop occurs again when loading.

School of Mechanical Engineering and Automation. He is now an assistant engineer in the gas department of Jigang Steel Maintenance Engineering Company, and is engaged in equipment management.

2.2 Analysis of the cause of the failure Analysis of the equipment failure phenomenon, the maintenance personnel initially determined the vibration of the secondary shaft vibration of the air compressor caused by the failure of the machine has two reasons: First, the air compressor secondary shaft vibration displacement detection component is damaged; second, air pressure There is an abnormality in the secondary bearing bush or the primary or secondary rotor.

According to the principle of troubleshooting, it is easy to check the principle of first easy and then difficult. Firstly, the vibration vibration detecting component of the secondary shaft of the air compressor is inspected, and no abnormality is detected in the detecting component. After the inspection is completed, the test is carried out again. The fault phenomenon is exactly the same as that during the first test. After the second test run, the cause of the fault shutdown caused by the damage of the test component can be eliminated. Subsequently, the air compressor speed increase box was disassembled, and the use of the secondary bearing bush was checked, and no abnormality was found. Finally, the first and second intake pipes are disassembled, and the operation of the first and second impellers is checked. It is found that the edge of the secondary impeller blades is damaged, which is the direct cause of the vibration displacement of the secondary shaft.

There are two reasons for the edge curling damage of the secondary impeller blades: foreign objects enter the human body in the second impeller volute; the equipment runs for a long time, and the impeller itself is fatigue damaged. After on-site inspection of the equipment, the first-stage impeller and the third-stage impeller were intact, but it was found that the condensate drainage of the primary cooler was not smooth, and the inner wall of the cooler was seriously corroded. Therefore, it can be inferred that the main cause of the damage of the secondary impeller is that the rust and rust off the inner wall of the primary cooler enters the secondary volute with the airflow, which causes the edge of the impeller blade to be damaged, rather than the fatigue damage of the impeller itself caused by long-term operation of the equipment. . 2.3 Troubleshooting measures 1) Disassemble the first and second rotors of the air compressor to the manufacturer, perform the grinding and trimming of the edge of the secondary impeller blades, and then perform the high-speed dynamic balance test on the first and second rotors. 2) Open the gas cooler side of the primary cooler and use a vacuum cleaner to clean the rust and other foreign matter in the cooler. Then, the first-stage cooler gas-side sewage pipeline is repaired to ensure that the condensed water generated during the operation of the equipment can be discharged in time. 3) Using the opportunity of disassembling the speed increasing box, open the bearing bushes at all levels to check and clean the carbon deposits and burrs on the surface of the bearing bush to avoid the bearing bush failure during the operation of the equipment. 4) After the first-level rotor repair and dynamic balance test passed, the equipment installation will be resumed. The center alignment of the motor and the speed-increasing box will be re-checked during installation. The results show that the alignment is good. (Continued on page 77) Wang Jinxiu and other hot-rolled wide-band ICDP roll eddy current testing technology application of eddy current testing interface crack defects, may be the phase change of the local structure of the roll, at this time can accept the roll.

The state of the roll surface before the coarse grinding of the roll and the indication of the flaw detection are known from the working principle of the eddy current flaw detection. The eddy current flaw detection is not sensitive to the surface and spot defects of the roll surface. Therefore, the surface of the roll surface, such as pores, indentations and spot peeling, may be indicated by the flaw. Small and easy to cause missed inspection, so the roll grinding needs to be carefully checked with the naked eye. If only the eddy current test is used, it is easy to cause the defect to cause the defect roller to be on the machine.

When the indication value of the eddy current flaw is high, the circumferential direction of the corresponding part of the roll should be carefully checked. In this case, the mechanical crack is the most dangerous and not easy to eliminate. The surface crack is usually deep and its subcutaneous The strike is at an oblique angle to the tangential direction of the roll surface. The roll surface crack will be quickly tested to the subcutaneous fatigue in the use of the roll (upper page 75). After the air compressor is normally loaded, the on-line detection value of the secondary shaft vibration displacement is 15.6|JLm, and the equipment is stable. .

2.4 Precautions in the inspection process When disassembling the first and second rotors of the air compressor, because the first-stage impeller is inconvenient to disassemble, firstly disassemble the second-stage impeller, then disassemble the first-stage gas seal and the oil seal in sequence, and finally from the first-stage volute The center pulls the rotor out. During the rotor disassembly process, it is difficult to perform the secondary impeller back cap and the first and second air seals. In order to facilitate the installation, the back cap is modified, that is, two parallel planes are manually processed on the conical surface of the back cap, so that the 30mm fork wrench can be used to disassemble the back cap. In order to solve the problem that the gas seal bolt is difficult to disassemble, the inner hexagonal bolt tail is modified, and the original round tail is changed into a regular hexagon, which is more convenient and quicker to disassemble, and improves the maintenance efficiency.

Each gap value is measured. After the first and second rotors are reloaded, in order to ensure a successful trial, a number of strict gap values ​​are measured, which have the following aspects. 1) Using the lifting shaft method to measure the extension between the various bushings, after reaching the depth of the composite roller joint layer, it will continue to expand along the path substantially parallel to the roller surface, and will be unstable after reaching the critical crack area, thus forming the roll belt. Fracture peeling off.

The operation measures for the characteristics of eddy current testing are as follows: 1) Selecting the end of fine grinding to perform eddy current testing, avoiding the interference of the fatigue layer of the roll on the flaw detection value, and making the eddy current display more realistic and accurate. In the process of grinding, the flaws appear to be too small and small, and must be carefully inspected with the naked eye at the corresponding roll position. If the crack is long, the grinding is paused, and the depth of the flaw is confirmed by ultrasonic flaw detection before deciding whether to grind.

3) In order to avoid the existence of defects such as pores and pits which are not sensitive to eddy current testing, the roll surface of the finishing section after the finishing is visually inspected by grinding.

4) After the use of the pattern roller, in order to prevent the residual mechanical crack caused by the stress concentration at the bottom of the groove, the grinding amount of the pattern roller to be flat roller must be greater than 8 mm, and the flaw detection should be strengthened in the subsequent work and grinding process.

3 Conclusion After the application of eddy current testing technology, the rolling mill operating rate is increased, the unplanned roll changing rate is reduced by 12%; the surface defect rate of the sheet is reduced, the scrap rate caused by the roll printing is reduced by 0.6%; and the machining grinding is reduced. The amount of single grinding of the milk stick decreased from 0.312mm to 0.245mm; the roller consumption of Laigang 1500mm hot rolling production line was reduced by 0.19kg/t, and the annual benefit was 64.125 million yuan.

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