Analysis and measures for the decommissioning of air compressors in light hydrocarbon facilities
The screw air compressor has the characteristics of high efficiency, automatic monitoring and economic operation, high reliability, simple maintenance, low noise and low vibration. 1 Impact of air compressor failure on the device When two air compressors in Shuanghe Station are in normal state, one of them can be started to meet the production needs, and the Other one is used as a backup machine in an emergency to ensure normal production. These two air compressors The drying system is connected in parallel through the pipeline. The maximum working pressure of the air compressor is 0.75 MPa. The compressed air discharged from the air compressor is first dehydrated by the drying system and then enters the air storage tank. When the air pressure stored in the air storage tank is low, When the air compressor is loaded with pressure, the air compressor starts to load compressed air. When the air storage tank pressure is higher than the air compressor unloading pressure, the air compressor starts to unload and stop the compressed air, so that the air storage tank always maintains a certain pressure and the air storage tank is compressed. The air is supplied directly to the pneumatic control valve of the production unit. Schematic diagram of the air compressor system process flow Because the air compressor backup machine and the working machine are not interlocked, even if the working machine is stopped, the backup machine will not start automatically, and the air compressor does not have any operation signal to be introduced into the light hydrocarbon operation central control room. The air compressor has a fault shutdown. There is no display in the control room of the light hydrocarbon operation. If the operator cannot find and process it in time, the production device will have no instrument wind or the instrument wind will be lower than the minimum working pressure required by the pneumatic valve. Failure, the temperature, pressure, liquid level and other parameters of the entire light hydrocarbon plant production can not be adjusted normally, it is easy to cause over-temperature and over-pressure operation of the production device, which brings safety hazards to the production; at the same time, the temperature and pressure of the light hydrocarbon device The violent fluctuations caused by parameters such as liquid level directly affect the smooth operation of the light hydrocarbon plant. According to the characteristics of continuity and stability of natural gas treatment, even if the instrument wind problem is dealt with, it takes a long time to produce qualified products, which directly affects the output of the device and causes economic losses. It can be seen that if the air compressor fails to be detected in time, it will bring a very large safety hazard and economic loss to the production. 2 Air compressor failure and cause analysis The air compressor of the light hydrocarbon plant of Shuanghe Station of the North Shaanxi Project Department is set to alarm when the exhaust temperature exceeds 110 °C. When it reaches 120 °C, it will automatically stop and stop. In the production process, it is found that after the air compressor is operated for a period of time, the automatic automatic protection and shutdown is always carried out, especially during the summer production period, which frequently causes the production device to fail to produce normally. Through the inspection of the air compressor, it was found that the air compressor was stopped, the computer controller showed that the exhaust gas temperature was too high (displayed over 120 °C) or the motor overload caused automatic protection shutdown. Check the sensitivity of the air compressor mechanical equipment and the calibration instrument. Any abnormalities were found, indicating that the air compressor was shut down because the relevant parameters were too high and the automatic protection was stopped. Therefore, the main reasons for the high exhaust gas temperature and motor overload are as follows: 1. The main factors affecting the high exhaust gas temperature and motor overload are as follows: 2.1 Air compressor working pressure is high If the working pressure of the air compressor is high, the air compressor must be set to a higher exhaust pressure, the exhaust pressure is high, the air compression ratio is large, and the generated heat is also increased; therefore, the higher the pressure setting, the exhaust temperature. The higher the natural, the higher the exhaust pressure, the higher the motor load, which makes it easy to cause high air compressor exhaust temperatures and motor overload. 2. 2 Motor loading frequently If the motor is loaded frequently, it will cause long running time of the motor with load, short running time of empty load, easy to cause overload and high temperature of the motor, which will increase the temperature of the whole air compressor system and cause high exhaust temperature of the air compressor. . 3 Measures taken for air compressor downtime 3. 1 Reduce exhaust pressure The inspection found that the current working pressure of the air compressor is set to 0. 75 MPa, and all the pneumatic valves of the statistical field device find that the highest working pressure of the pneumatic valve is 0. 45 MPa, which is obviously the highest setting of the current air compressor. The exhaust pressure is significantly higher than the pneumatic pressure required for the regulator valve. If the compressor pressure is reduced, the exhaust temperature can be reduced and the motor load can be reduced. According to the actual situation and after many tests, we set the maximum exhaust pressure of the air compressor to 0.68 MPa, which reduces the maximum working pressure of the air compressor. 3. 2 Solve the frequency of motor loading The frequency difference between the unloading pressure and the loading pressure of the air compressor is affected by the frequent loading of the motor. The smaller the pressure difference is, the more frequent the motor is loaded. The lowest loading pressure of the air compressor is 0. 72 MPa and the maximum exhaust pressure of the air compressor is 0. The pressure difference of 75 MPa is only 0.03 MPa. Since the air storage tank itself can store a certain pressure for the field device equipment, if we increase the difference between the unloading pressure and the loading pressure, the motor loading times will decrease, the motor The empty load running time will increase accordingly. The pressure difference between the unloading pressure and the loading pressure is increased by the pressure difference of 0. 56 MPa and the newly set unloading pressure of 0. 68 MPa. Reduced frequent loading of the motor. 3. 3 Purge air cooler According to the actual situation of dust in the large wind and sand in northern Shaanxi, the air cooler of the air compressor is usually cleaned every two months, and in the summer, it should be cleaned once every half month to ensure the air cooling fins can be smoothly ventilated. The system temperature can be quickly discharged. 4 Reform air compressor stop interlock start Through the above rectification measures, we solved the problem of air compressor shutdown caused by excessive air compressor exhaust temperature and motor overload. Although it can ensure that the air compressor does not stop frequently, the various failure factors of the air compressor still exist. The working air compressor will be shut down and the other standby machine can be operated to ensure the supply of the instrument wind and ensure the normal production. Through this idea, we consulted the data and found that if the air compressor has no loss of compressed air after the maximum working pressure is unloaded or the air pressure is not lower than the loading pressure for a long time, the motor of the working air compressor will automatically stop, but The program is turned on. If the air pressure drops to the loading pressure of the air compressor, the air compressor will automatically start the motor to make the air compressor run. Therefore, we let the two air compressors start paralleling at the same time. 5 implementation effect The air compressor is one of the important equipments to ensure the safe, continuous and smooth operation of the light hydrocarbon plant. By adopting the above measures, the problem of frequent shutdown of the air compressor is solved, and the safety brought by the air compressor shutdown to the light hydrocarbon device is eliminated. Hidden dangers ensure that the continuous and stable production of light hydrocarbon plants increases the production of light hydrocarbons, and the shutdown of the two air compressors after the transformation starts, which ensures the smooth supply of the instrument air of the automatic regulating valve. 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