This article teaches you how to monitor the condition of the air compressor and use the condition monitoring data to analyze some problems in the air compressor, which is outlined in detail through three major points below.
1、Use condition monitoring to control air compressor operating parameters
The two compressors are installed with vibration online monitoring system produced by Nanjing Turbine High-Tech Development Company, which mainly monitors the vibration displacement values of the four-stage journals in X and Y directions relative to the shaft tiles. At the same time, bearing temperature, oil temperature, oil pressure, air volume intake and exhaust pressure and temperature at all levels of the compressor are displayed on the main control computer. The operation of the whole air compressor can be monitored without interruption.
Since Daye did not have large oxygen production equipment before and lacked the necessary practical experience, it was often difficult to achieve good control by merely referring to the manual for rigid operation, therefore, the information provided by this monitoring system played an irreplaceable role in the correct operation out control of the air compressor. For example, during the start-up phase, after the guide vane is opened from the start-up position to 30, if the compressor is immediately pressurized, we will see that the vibration at all levels is significantly higher and very unstable, and it is determined to be low-pressure wheezing. Therefore, we improve the operation by opening the guide vane to 65 or more after driving, then come to boost the pressure, and if we don't need so much air volume, then close the guide vane to the right position, so as to avoid the low-pressure wheezing in the driving stage.
As such a large equipment, we will reduce its vibration as the main task of operation control, from 1 #, 2 # air compressor to see 1 # air compressor using 32 # turbine oil, 2 # air compressor for some reason is using 46 # oil, we through the monitoring system obtained by the 1 # air compressor a large number of dynamic line parameters of statistical analysis, found that the oil temperature control at about 35 #, its vibration condition; and for 2 # We found that the vibration of the air compressor is good when the oil temperature is controlled at 40#, and the vibration can be reduced by about 8% compared with the oil temperature at 35#.
The motor power of the air compressor is as high as 3400kW, which is the major energy consumer in our factory.
As the capacity of air compressor has certain affluence, by closing the small import guide vane and reducing the amount of air released, we can achieve obvious energy-saving effect. However, when the guide vane opening is too small, the vibration will increase again, and we have solved this contradiction better through condition monitoring.
2. Correct judgment avoids major equipment accidents of series DH air compressor
The vibration of the series control compressor had been running well from 1997 to June 1998, but an abnormal situation appeared in July 1998. We will compare for the vibration of the stage shaft at several typical moments. at 6:04 on July 9, there was no abnormality in the air compressor.
At 7:15 and 7:23 on July 9, the air compressor made an instant abnormal sound, and at the same time, the temperature of the grade bearing had an obvious rising spike at these two moments, the temperature rose from 55# to 62#, and at 8:10, the bearings at all levels were stopped and checked, there were only some large contact bright spots, and after making slight repair, the bearing temperature of the air compressor was started again at 20:15 on July 10, 58#, through the above Three moments of vibration comparison and analysis, found in the abnormal when the vibration amplitude suddenly climbed abnormally, bearing temperature changes dramatically, accompanied by a sharp scream, while in the vibration step spectrum showed the industrial frequency spikes, must be the rotor part of the abnormal damage, resulting in sudden destruction of the rotor dynamic balance. It was decided decisively to stop running the compressor at 00:50 on July 11, when it was initially determined that the abnormal condition of the compressor might be caused by a serious imbalance of the rotor system and damage to the grade impeller. After disassembly and inspection, it was found that it was much more serious than we expected. The stage impeller cover had two radial penetrating cracks, each over 100mm long, and another crack at the end seal port ring. If this rotor continues to run, the cracks will expand rapidly, which will surely cause the impeller to break and break the big cover of the compressor to fly out, the high-speed rotor will suddenly destabilize and destroy all the bearings, which will lead to the scrapping of the whole compressor, and the flying debris may also cause significant casualties, and the loss will be very huge.
3、Provide the basis for the replacement of spare parts for series II air compressor
Ⅱ series air compressor high-speed rotor, since 1997 operation shaft vibration has been at a higher level, level 65m, % 56m, beyond the allowable range of vibration.
Although the vibration amplitude is relatively large, but more stable, vibration frequency characteristics, mainly in the high-speed shaft work frequency 200Hz or so, it is obvious that the high-speed rotor dynamic balance there are large problems. The high-speed rotor will be repeatedly dynamic balance verification, found that the rotor's dynamic unbalance of the phase angle is extremely unstable, the application of double-sided de-weighting method can not find the de-weighting position. Initially decided that the rotor in the manufacturing or assembly there are defects, because this kind of defects are very hidden, must be sent back to the manufacturer to thoroughly check the treatment to solve. In order to shorten the downtime, we purchased a new set of rotors, and after replacing them, the vibration of the unit dropped significantly, with an average of 32m at the level and 28m at the % level, reaching a good operating condition. The cost of acquiring a set of rotors is very expensive, and it is obviously difficult to make up one's mind to implement without sufficient theoretical basis and realistic requirements.