Cause Analysis and Treatment of Fluctuation of Guide Vane of Air Compressor
Analysis and Treatment of Fluctuation of Inlet Guide Vane of Chemical Design Communication Air Compressor Zhang Xiping, Zhao Lifu Offshore Oil Tianye Chemical Co., Ltd. Annual production of 300kt synthetic ammonia, 520 kt urea plant was introduced in the early 1990s. There are two centrifugal compressors, an air compressor and a nitrogen compressor, for the air separation of 23,000 m3/h. Among them, the air compressor is a radial isothermal centrifugal compressor produced by Sulzer, Switzerland. It has 5 stages and is driven by steam turbine. The main design parameters of the compressor are as follows: speed 5 outlet temperature 128 °C normal power raw air first The self-cleaning air filter removes dust and other mechanical impurities and controls the flow through the inlet vanes to enter the impeller for compression. After each compression of the first three stages of the impeller, the air is cooled by an internal cooler provided on both sides of the cylinder, and the condensed water is separated in the matching steam trap, and then compressed in the fourth and fifth stages. After entering the aftercooler, the cooled air enters the air cooling tower. There is an anti-surge vent line in front of the aftercooler, which is used as an outlet pressure assistant engineer when driving or abnormal conditions, working in the warehousing department of CNOOC Tianye Chemical Railway. C (pay attention to the temperature control and measurement accuracy, and then measure the temperature evenly); (4) repair the defect part with argon arc, temper after welding, temperature 680720 C, holding time 2h; (5 ) Use a special tool () to turn the cylinder partition groove. The special tool for the turning tool is mounted on the bearing housing of the steam turbine. The 1kW output motor drives the planetary reducer (20r/min) to directly drive the dummy shaft. Manually adjust the cutter head screw and top wire, and then find the positive groove and then turn it to ensure the size after turning. Finally, the spacer groove is polished with 100 sandpaper to ensure surface roughness. Reload the partition and measure the fit clearance to meet the requirements. 3 Conclusion The repair of the steam turbine cylinder baffle groove solves the problem of over-displacement and corrosion of the baffle groove matching gap, which lays a foundation for the safe operation of the steam turbine, prolongs the service life of the cylinder block, saves maintenance funds, and is used for future steam turbines. Maintenance has tried a new road. The chemical design communication was adjusted to prevent the air compressor from falling into the surge zone. The air compressor is designed for constant speed operation. The flow adjustment is controlled by the inlet guide vane opening, that is, the change of the rotation angle, so that the inlet airflow direction and the flow passage area are changed, thereby controlling the intake air amount. The adjustment range is 9°110°. The guide vane is a single supporting blade, which is signaled by the DCS during operation, and the piston type actuator causes the piston type actuator to drive the connecting rod to control the vane to realize flow control. 2 Problems existed On February 21, 2010, the inlet guide vanes began to fluctuate. When the device was stable and the working conditions were not adjusted, the air flow rate changed by about 1 000 m3/h in 20 s, due to the change. Too obvious, there is no threat to the normal operation of the device, the reason is not clear, can only be temporarily controlled and observed, and analyzed to find the cause of fluctuations. However, the amplitude and frequency of the fluctuations became larger and larger. By March 13, the flow rate increased to 4000m3/h, and the frequency increased from 12 times/d to 45 times/d. For this reason, the link stroke has to be The limit is set so that it can only operate within a certain range, so that the instantaneous fluctuation of the device does not affect the stable operation of the device. 3 Reason analysis 3.1 Process aspect Before the inlet guide vane fluctuates, the process parameters are not obviously abnormal, the actual flow rate is also far from the surge line, and the processing air volume is not adjusted. When the fluctuation occurs, it is not during the molecular sieve switching period. factor. 3.2 The inlet filter of the equipment is replaced recently, the pressure difference is 0.3 kPa, and there is no damage. The possibility of flow fluctuation due to excessive resistance of the air filter chamber does not exist. From the operating parameters, the inlet and outlet temperatures of the intercoolers do not exceed the design value, and the cooling effect is good, which will not cause the air compressor to reduce or fluctuate. From the perspective of the compressor body, the factors affecting the flow rate include impellers, diffusers, bends, and return flow devices. If these components are clogged or fouled, they will first be expressed in terms of vibration and other parameters. In the case where there is no abnormal change in the vibration value, it is obvious that it is not a problem of the device itself. 3.3 Instrumentation After the above analysis, the problem is concentrated in the instrument aspect. The inspection found that the inlet guide vane instrument has a large amount of dust in the air. After the discharge is blown off, the number of vane fluctuations is reduced, but there are still fluctuations. It is judged that there may be a blockage inside the valve positioner, etc. Dealing with the problem. 4 Problem Handling The inlet guide vane is closed when the air is lost, and the positioner must be disconnected from the instrument air when the air compressor is running. Therefore, the limit of the connecting rod is first strengthened to ensure that the vane is broken when the instrument air is broken. No action, the preparation of the corresponding instrument is also ready. On April 3, the positioner inspection was dismantled and it was found that a large amount of aluminum glue molecular sieve dust for adsorbing moisture in the instrument air dryer was accumulated in the nozzle, and was cleaned up and put back into use. Checking the results of the treatment confirmed the previous judgment that the inlet guide vanes did not fluctuate again. 5 Precautionary measures Obviously, the key to preventing similar faults is to strengthen the management of instrument air. The following measures have been taken for this purpose. (1) All partially pulverized instrument air dryer adsorbents were replaced. (2) Through the transformation, reduce the pressure relief rate during the regeneration of the adsorbent of the dryer, increase the regeneration temperature and the amount of regeneration gas, and prevent the adsorbent from being powdered due to excessive pressure relief or incomplete regeneration. (3) Install a separation tank on the inlet guide vane instrument air line to separate the dust that may be brought from the instrument air. (4) Closely monitor the pressure difference between the instrument air dryer before and after, and periodically open the instrument air line guide to check for dust. 6 Summary Air compressor inlet guide vane fluctuations seriously threaten the safe and stable operation of the device. On the one hand, it will have a serious impact on the stable operation of the air compressor itself, which may cause surge and no-load phenomenon of the compressor; on the other hand, it will also cause great harm to air separation conditions and equipment. If the fluctuation range is large and the frequency is too high, the pressure difference between the air cooling tower and the molecular sieve exceeds the design value, and even the tray may be overturned, the molecular sieve is powdered, and the bed is not equal. Shortly after the vane wave fluctuation fault was eliminated, the air separation device appeared to have the processing air volume exceeding 128km3/h, and the cooling water was brought into the molecular sieve, and the C2 exceeding the standard in the cold box air had to be limited to load. After the overhaul in August 2011, the internal inspection of the air cooling tower found that some of the tower downcomers were damaged. The analysis concluded that this was caused by the fluctuation of the inlet guide vanes. Therefore, once the inlet guide vane is found to have abnormal fluctuations, it must first be mechanically restricted, and then find the cause and take corresponding measures to avoid more serious consequences. Moving Gantry Leveling(Straighting) Hydraulic Press Moving Gantry Hydraulic Press,Leveling Of Various Steel Plates,Gantry Leveling Hydraulic Press,Gantry Straightening Hydraulic Press Wuxi DALI Hydraulic Machinery Factory , https://www.hydraumatic.com