Laigang Tianyuan Gas Company's 5 oxygen generator unit is KZONAr-9000/6000/370 air separation unit. Its supporting Shenyang blower factory produces DH71 with a force of 0.51MPa, motor speed of 1500r/min, ―, two-stage rotor speed of 8739r/min, three or four stages. 2. Fault phenomenon April 8, 2010, 5 oxygen generators by 3 The hot standby state of the month was transferred to the driving production. The air compressor was successfully started in the normal state before the start of the startup, and the operating parameters were normal compared with the historical data. After ten days of operation, the DCS monitoring value of the air compressor showed that the vibration of the first and second rotors gradually increased from 643um to 64um (the alarm value was 61um), and the maximum was 69um, which was close to the chain parking value (75um). There is no obvious change in the running flow, pressure, and discharge temperature. The gap between the detection sensor probes is normal, and the instrument has no obvious faults. Looking at the DCS vibration trend graph, it is found that the vibration rise is synchronous with the oil temperature rise fluctuation, and the bearing temperature is relatively stable. The increase in oil temperature is related to the increase in the temperature of the oil cooling water caused by the increase in ambient temperature. Signal acquisition was performed on the vibration of the air compressor using the Inventec EN900 offline vibration acquisition analyzer. Compared with the original data, the spectrogram shows that the ratio of the first harmonic wave of the first and second rotors to the effective value of the vibration is higher, the rise is obvious, and the waveform diagram and the purification axis trajectory have no obvious change. In addition, it is multiplied by 714 in the horizontal direction of vibration and has a sideband (,). Judging from the slow change of the vibration value and the fall of the oil temperature fluctuation, it is considered that the rotor imbalance is the main cause of the vibration, and the oil temperature is increased to make the oil film thin and the vibration is increased. The 714 multiplier is a high frequency band, and there is a high possibility that gear meshing is poor due to its wide sideband.
3. Fault check and treatment Due to the continuous high temperature of the weather, although the measures of adding the circulating cooling water fan to reduce the water temperature and opening the oil cooler to the maximum, the air compressor shaft vibration is still operating in the super alarm state, and there is a chain at any time. Parking is possible. On June 12, the use of external air consumption reduction opportunities was used to overhaul the air compressor parking. Because the air compressor rotor was last balanced in October 2007, the inspection focused on the impeller rotor, gears and bearings. Dismantle the air compressor rotor, impeller and gearbox, bearing. After disintegration, it was found that the first and second impellers of the air compressor were severely fouled, and the scale was partially peeled off. The main components of the test scale were Fe304 and dust. Analysis shows that the fouling on the impeller is the main cause of the rotor imbalance and high vibration. The fouling is formed by the oxidative corrosion of the inner wall of the suction pipe of the air compressor and the adhesion of dust in the air to the impeller during the compression process. Checking the gear meshing situation revealed that there was a noticeable wear scar on the edge of the spindle gear near the top of the tooth tip, which was suspected to be caused by foreign matter entering. Inspection of the rotor bearing fit clearance is within the technical requirements.
Treatment measures: The impeller scale was cleaned with high pressure water (1020 MPa), and all were removed until the impeller color was seen. Replace the self-cleaning filter cartridge in the air suction chamber. The large and small gears were inspected in detail, and no other abnormalities were found, and no foreign matter was found. Oil quality testing of the lubricating oil in the fuel tank is carried out and filtered by an off-line coalescing oil filter. The test index is within the acceptable range. A pipe and a shut-off valve are added next to the oil cooler cooling water inlet to prepare the cooling water from the freezer to reduce the water temperature.
The installation was resumed after the treatment was completed, and the test was carried out on June 13. The unit operated smoothly after driving. After adding to the normal load, the vibration of the first and second rotors is maintained at about 57um, and the vibration of the third and fourth stages is slightly higher than that before the maintenance. The air compressor was operated for more than two months, the ambient temperature rose to the highest, the water temperature and oil temperature also rose to the highest, and the air compressor was running normally and smoothly.
Through the handling of this fault, the importance of preventing impeller fouling is recognized. Make sure that the air filter cartridge replacement cycle is changed from the original one year to six months. An impeller cleaning device can be added to the condition. When the air compressor is parked for a long time, nitrogen gas should be introduced into the air inlet and passage of the carbon steel pipe to prevent oxidation and corrosion. The lubricating oil should be tested and filtered before driving to prevent the wax from coalescing into a film, which will affect the cooling effect and increase the oil temperature. It is necessary to further strengthen the vibration monitoring and deterioration trend comparison analysis of the air compressor gear to detect the occurrence of gear failure and prevent the sudden failure. Even if it is short-term hot standby, maintenance work should be done well. The inspection and maintenance preparation before driving should be as full as possible to prevent parking failures that may occur during operation and reduce the number of parking stops.
(Continued from page 389) 460MW supercritical CFB boiler, the world's first and currently the world's largest supercritical CFB boiler.
5. New opportunities and development prospects of circulating fluidized bed boiler technology The circulating fluidized bed boiler combustion technology is the best clean coal combustion technology with commercial operation. With the continuous reduction of global coal reserves and the continuous improvement of environmental protection requirements, new opportunities have been brought to the development and promotion of circulating fluidized beds.
1) Coal is an important chemical raw material. As the reserves continue to decrease, large-scale pulverized coal boilers will gradually be restricted by the state. The circulating fluidized bed is suitable for burning various fuels, and it is a good project for urban garbage disposal, which will inevitably be supported by the government.
2) At present, the national thermal power plants have responded to the requirements of the State Environmental Protection Administration and have launched the desulfurization project. However, as a pulverized coal boiler, it is difficult to adopt dry desulfurization technology due to structural limitations, so limestone wet desulfurization is mostly used. Wet desulfurization requires a large investment in desulfurization equipment such as flue, booster, absorption tower, limestone slurry system, gypsum dewatering system, wastewater system, limestone powder preparation system. The circulating fluidized bed boiler can be desulfurized by dry spraying in the furnace, and even denitrification can be realized, and the increased investment is small, and the system desulfurization rate is increased to over 80%.
3) Circulating fluidized bed in the use of high-ash, low-volatility or high-sulfur and other inferior fuels that are difficult to adapt, and peak-loading power plants with high load requirements and self-supplied power plants with high load fluctuations Boiler combustion technology is the best choice. The international community has developed in the direction of large-scale. The 220/th, 41oth/circulating fluidized bed boiler developed in China has been put into operation. Therefore, circulating fluidized bed boilers have strong vitality in the domestic and foreign markets, and have far-reaching significance for its development.
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