Vibration. This paper briefly describes the characteristics and hazards of the surge mechanism of the centrifugal air compressor, and how to prevent the centrifugal air compressor when the summer temperature rises; the shooting and the female å· 1; Bifurcation, introduction of centrifugal air music reduction machine, corpse-powered medium gas compressor. The basic working principle is to increase the kinetic energy of gas molecules with a high-speed rotating impeller. After the diffuser, the kinetic energy of gas production is converted into pressure energy. 1. It has a large amount of exhaust gas and high efficiency. Simple structure. The volume is small, the gas is not polluted by oil, and the smooth running airflow under normal working conditions is not pulsating. However, centrifugal air compressors are sensitive to changes in gas pressure flow temperature and are prone to surge. Surgery is especially frequent when the summer temperatures are high. 2 Mechanism of Surge Surge is the periodic oscillation of the medium in fluid machinery and its pipelines, which is the mechanical vibration that occurs when the medium is excited by periodic suction and discharge. In a centrifugal air compressor, surge is a common fault in the operation of the compressor and is an advancement in the rotation stall. When the centrifugal type reducer is reduced to a certain extent, the compressed gas will form a de-flowing group on the non-working surface of the impeller, and the impact loss will increase sharply, which not only increases the flow loss, but also causes the airflow to decrease. The pipe network is returned to the compressor, causing strong vibration of the fuselage and issuing asthma or screaming Lu. This phenomenon is called the end vibration of the centrifugal compressor. 5 determined speeds, total corresponding flow values, compressor efficiency reached the highest point. When the flow rate is greater or less than this value, the efficiency will drop. As usual, the operating point of this flow is the design condition point. The performance of the compressor is affected by the surge condition on the left side of the line, which is called the stable working condition area of ​​the compressor. Stable working condition area When the compressor is in operation, if the flow rate is reduced due to external reasons, it will cause serious rotation and detachment in the flow path of the shrinking machine. If the gas volume is reduced, the whole of the compressor impeller The flow channel is occupied by the vortex zone of the airflow. At this time, the pressure of the compressor will suddenly drop by one. However, the pressure in the larger capacity pipe network connected to the compressor does not drop immediately. The phenomenon in which the gas flows back to the compressor. When the pressure in the pipe network drops below the discharge pressure of the compressor outlet, the gas backflow will stop and the compressor will resume venting to the pipe network. However, because of the amount of intake air, a vortex zone appears in the flow path. As a result of this cycle, the flow rate in the unit and the pipeline will change periodically. The pressure on the inlet and outlet of the machine will be greatly pulsated. As the gas flows back and forth in the compressor inlet and outlet, it is accompanied by a large periodic airflow hum and severe machine vibration, which fluctuates in the pressure flow 1 of the instrument operating panel; it can be clearly reflected in the No. 1 recording. The operating site can also be immediately noticed. The vibration of the machine caused by the surge. The rate of the amplitude tube is closely related to the size of the volume. The larger the volume of the tube network, the lower the surge frequency and the larger the amplitude. The exhaust pipe network capacity of these machines is very large. At this time, the surge frequency is even smaller than that of the 汜3 surge characteristic. The compressor is characterized by the following conditions. Under normal conditions, the compressor vibration is relatively stable and the amplitude is small. When the compressor approaches or enters the surge condition, the cylinder and the bearing will vibrate strongly. The amplitude is much higher than that during normal operation, and the frequency is low. Under normal conditions of VSl3CH, the compressor outlet pressure and inlet flow rate change little, and the measured data fluctuates around the average value with a small amplitude. When the compressor approaches or enters the surge condition, the change of the outlet pressure and the inlet flow rate are large, and periodic and large-scale pulsation occurs, and sometimes the gas may flow backward from the compressor inlet. Under normal conditions, the compressor noise is small and it is high and low when it is continuous, causing periodic changes. When entering the surge condition, the noise increased dramatically and even a popping sound appeared. 4 Surge of the surge The surge phenomenon is very harmful to the compressor. Mainly now, the following aspects will sway, which will greatly fluctuate the pressure flow of the gas supply parameters and damage the stability of the plant process system. The blade will vibrate strongly, the impeller stress will increase greatly, and the noise will increase. The friction and collision of the static and dynamic components are caused, and the shaft of the compressor is bent and deformed. When the shaft is severe, the shaft curtain is moved and the impeller is damaged. The bearing journal wear is aggravated, the stability of the lubricating oil strand is destroyed, and the bearing alloy is fatigue cracked and even burned. 51 Damage to the interstage seal and shaft seal of the compressor, which reduces the efficiency of the compressor and even causes an explosion fire. 61 affects the normal operation of other sets of equipment connected to the reducer, 1 disturbs the normal operation of the operator, so that the accuracy of the instrument is reduced, and even the fire spirit. Surge is the inherent characteristic of the air compressor caused by the compressibility of the gas. It is also suitable for the unique phenomenon of the centrifugal air compressor. Therefore, anti-surge becomes the most important protection device for the centrifugal air compressor control system. Surging control is very important, because the surge will occur in a + safe working state. Therefore, if the operation may cause the flow to drop below the centrifugal compressor surge flow. Then you should set up the surge control system. 5 Surgery measures for surge and improvement Surge protection device for 51 compressors The miscellaneous air compressor in the power plant of Guixi Smelter is a 38-type 3-stage compression centrifugal air compressor of American Yaoxing Company. The air compressor has an automatic dual flow limit control. When the system pressure reaches the set pressure of the air compressor, the inlet guide vanes will slowly close, and the air continues to output at the required rate and relative pressure. If the system demand continues to fall below the range of stable operation of the air compressor, the inlet guide vanes will be closed to the minimum opening, and at the same time, on the exhaust line of the air compressor, the air will be discharged through the vent valve at the front end of the check valve. atmosphere. Through the previous introduction, we know that the direct cause of air compressor surge is that the inlet flow is less salty, and the reduction of the mouth flow directly leads to the reduction of the air compressor load. The negative pressure of the air compressor is reduced. The intuitive response is that the motor current is reduced. Most air compressors are equipped with anti-surge devices. Their working principle is basically the same, that is, when the air compressor is running close to the surge curve, the vent valve is opened to reduce the outlet pressure to prevent surge. The anti-surge slope setting adopted by one person 38 is the most common species. 2. By setting the ratio of system pressure to motor current, under the corresponding system pressure, if the current is lower than the set value, the air pressure is automatically turned on. The venting valve of the machine unloads the air compressor to prevent surge. 1 When the surge occurs, due to the strong pulsation of the airflow and the periodic vibration surge slope, the combination of 1 and 2 can be used to obtain the relationship between the surge venting of the centrifugal compressor and normal operation. 3 through 3, the compressor has a protective venting zone between normal operation and surge. Scared to play, the existence of Gang. Pay to avoid compressor surge, and the size of the venting area affects the utilization of the empty jade machine. Under the premise of the existence of the de-protected area, the workshop in the demolition area will be passed to the site for the surge test by the technicians of the 1 line, and the actual surge curve of the air compressor will be drawn, and then the internal pressure of the air compressor will be built. The surge slope was compared and it was found that the anti-surge slope was indeed too low, resulting in an excessively large venting area, which affected the utilization of the air compressor. Through the serious discussion between the workshop leaders and the electromechanical process personnel, the manufacturer reduced the venting area and expanded the normal working range of the air compressor. The modified line 4.1234 52 device shortage and artificially improved the anti-surge slope setting can effectively ensure the normal situation. The air compressor operates stably, but as the summer temperature increases, the power center reduces the amount of intake air, and the temperature rise also increases the internal resistance of the motor. Reduced the loss of downtime! Half the effort. Therefore, the motor current is often lower than the set value of the anti-surge slope, which causes the air compressor to vent frequently, which seriously threatens the safe operation of the air compressor, and sometimes has to be shut down for maintenance, thus affecting the operating efficiency of the air compressor. In response to the frequent anti-surge venting of high-temperature space-time presses, the workshop tried the following measures. Since the temperature rise is the root cause of frequent venting, the workshop passes various cooling measures, such as adding water-cooling facilities outside the plant to increase heat dissipation in the plant. The fan and the like have achieved a certain effect, and the number of times the air compressor is emptied has been slightly reduced. However, due to the large size of the plant and the large number of operating equipment, it is necessary to invest in the reduction of the temperature. Therefore, we need to find ways to reduce the number of emptying of the air compressor. Through the anti-surge slope of the air compressor, we can clearly see that the minimum current that triggers the venting is proportional to the set system pressure. So if we control the system pressure. Make the system force to the lower limit within the allowable range. It is possible to operate the equipment at a lower current without placing it. 4. In addition to the centrifugal empty jade machine, there are three smaller æ±´ complex air compressors. According to the change of the reaction force of the pipe network, the opening or stopping station or the two injection type air compressors can flexibly adjust the pressure of the pipe network to make the air compressor work at a lower level. System pressure changes are frequent. This makes the operator. Frequently need to start and stop equipment to adjust the system 1 force. Therefore, it is still necessary to find a suitable solution to the history. After the normal working area current is modified to prevent the surge slope, the air compressor operates well, which can effectively prevent surge. The utilization rate of equipment that has not been frequently released has been greatly improved. 6 summarize the summer temperatures. The air-free thinning makes the centrifugal air compressor less efficient and easy to surge. Therefore, pay attention to the heat dissipation of the equipment during the summer, and try to reduce the temperature of the equipment and the environment. ,Time. Appropriately, control the air pressure of the pipe network, try to shift the surge point downwards, and reduce the chance of surge. In addition, the surge curve of each air compressor has a slight difference, the equipment is initially low, manufacturers can go to the site to test the surge curve, so as to develop a more reasonable anti-surge slope and improve the operating efficiency of the equipment. . 1 Xu Zhong. Centrifugal compressor principle elbow. Mechanical Industry Press, 1990 2 Li Yongsheng. Anti-surge control of centrifugal compressors. Large nitrogen fertilizer. 2, 9.32 3 recommended Bao Zhi. Surge analysis and solution for centrifugal compressors, 1. China Compressed 4 Gu Yuyong, Zhang Mengchao. Discussion on the Surge Mechanism of Centrifugal Air Compressor and Anti-surge Control Method 0 China Compressor Network, 2,9 Electric Washing Outlet Pressure
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