Sichuan Nonferrous Metals Improve the Operation Stability of PTM Crane 2055 Air Compressor Xiang Bo, Deng Yongchun, Cheng Jia (Sichuan Qixing Aluminum Industry Co., Ltd., Meishan 620041, Sichuan) How to improve the operational stability of the ERC2055 air compressor Several improvement measures were proposed to make it run better and smoother in the summer, thus improving the advanced technology level of the electrolytic aluminum multi-function crane.
Aluminum electrolysis multi-function crane, also known as electrolyzer operation machine, referred to as PTM, which integrates mechanical, electrical, hydraulic, gas control and other specialties, is one of the key equipments for large-scale prebake electrolyzers. At present, most of the PTM cranes are equipped with the slide air compressor ERC2055 provided by Italy MATTEI, which provides continuous compressed air power source for the pneumatic components of each mechanism. Therefore, how to improve the running stability of ERC2055 air compressor under high temperature and heavy dust and strong corrosive environment is the basic condition for ensuring the reliable operation of electrolytic PTM crane, and is the key factor to promote the normal production of electrolysis.
1ERC2055 air compressor working principle and structure sliding vane air compressor working principle As shown, the rotor is placed eccentrically in the stator, and the rotor and stator inner cavity are tangent at a certain point. A slider groove is longitudinally machined in the axial direction of the rotor, and the slider is free to slide in the slider groove. When the rotor rotates, due to the centrifugal force, the sliding vanes in the vane groove will be pulled out against the inner wall of the stator. Thus, the two sliding vanes, the outer circular surface of the rotor, and the inner wall of the stator form a cavity which can change in volume as the rotor rotates. We call this variable inner cavity a primitive volume. It is the sliding vane air compressor that continuously changes the volume of the element to continuously output compressed air.
1 stator 2 rotor 3 sliding sheet single working chamber sliding vane principle to improve the running stability of PTM crane 2055 air compressor. The internal structure of the ERC2055 air compressor body is shown as %å©.
1. Air filter gas 2. Operation valve 3. Fuel tank 4. Compressed air chamber 5. Rotor 6. Oil cooler 7. Oil filter 8. Oil nozzle 9. Oil pressure relief valve 10. Oil water separator 11. Compressed air 12. Coalescing filter 13. Anti-vacuum valve 14. Low pressure backup valve 15. Safety valve 16. Return valve 17. Intake valve ERC2055 Air compressor internal structure 2 Common fault phenomenon and cause analysis Relative humidity in Meishan area, Sichuan Large, 7096%, the wind is small, the summer temperature is high and humid, the air in the electrolysis plant is not easy to circulate, the air compressor is installed on the driving beam, the surrounding temperature will be 50~60 °C, and the crane beam dust and Fluoride on the electrolytic cell has more corrosive gases and damages the components of the PTM crane. The air compressor does not stop running for a long time, especially during the summer heat, frequent high temperature alarm shutdown and electrical trip, which seriously affects the normal production of electrolysis. Common fault phenomena and causes are: 2.1 Fault phenomenon: air compressor caused by high temperature trip 2.1.1 Working environment analysis The external environment is relatively harsh, the ambient temperature is too high, the average summer temperature in the Meishan area of ​​Sichuan is 28 ° C, the electrolysis workshop Insulation structure design, the electrolytic cell in the normal production tank temperature is 850~900 °C, a large amount of heat will be generated to radiate into the air. The ambient temperature on the PTM crane running above the electrolyzer is 1 25~35 than the temperature of the ring i. 53~63°C. The sliding vane air compressor will generate a lot of heat, and it will be lubricated and cooled by the oil bath. The superheated lubricating oil will be cooled by the oil cooler and distributed to the surrounding air. Under normal operation, the air compressor is relatively The ambient temperature rise is about 30 °C, so the air compressor body temperature is between 8393 °C during normal operation of the air compressor.
2.1.2 Analysis of operating equipment When the air compressor is just started, the lubricating oil in the air compressor tends to have a lower temperature, or the temperature is usually lower than the lower limit of the optimal working temperature of the lubricating oil. The temperature of the lubricating oil is increased as soon as possible to avoid the lubricating oil running at low temperatures for a long time. When the temperature of the lubricating oil is lower than the temperature set by the bypass valve, the lubricating oil does not pass through the oil filter and directly enters the compression chamber through the oil filter, and the lubricating oil will generate a large amount of heat due to the air pressure opportunity. The temperature rises in a short time. When the temperature reaches the temperature set by the temperature control bypass valve, the bypass is cut off, and the lubricating oil enters the cooler for cooling, so that the temperature of the air compressor is kept within a reasonable range. Due to the action of the spring, the opening and closing of the temperature controlled bypass valve is a gradual process. See the circulation path of the lubricating oil of the vane air compressor.
The lubricating oil circulation path can be known. When a problem occurs in a certain part of the air compressor, or a certain part fails, the air compressor temperature will exceed the operating temperature, causing a high temperature alarm or an ultra high temperature alarm interlocking action shutdown. Many years of operation observation found that the air compressor is running at high temperature for the following reasons: (1) The cooling function of the oil cooler is reduced; the temperature difference between the oil inlet and the inlet of the oil cooler can be judged. Under normal conditions, the temperature difference is between 13 and 18 °C. At 13 ° C, the cooling effect of the oil cooler cannot meet the normal operation requirements of the air compressor. At this time, check whether there is too much dust and sludge on the oil cooler, and clean it up in time. Secondly, there is too much fouling in the pipeline to block the oil circuit. The lubricating oil cooled per unit time should be reduced, and the temperature drop can not meet the requirements.
(2) The temperature control bypass valve is faulty, causing the air compressor operating temperature to be abnormal.
Study on improving the running stability of PTM crane 2055 air compressor 1 Compression chamber 2 Oil filter 3 Temperature control Bypass valve 4 Cooler 5 Bypass temperature control Bypass valve principle Figure 2 Temperature control bypass valve on the sliding spool The temperature sensing probe controls the opening and closing of the valve core by the probe, and determines that the temperature control bypass valve opening temperature is within 70±10 ft; after long-term use, the probe has reduced efficiency and cannot operate at a normal temperature point, so that it comes out from the air compressor body. The hot lubricating oil cannot be or completely cooled back to the air compressor body through the oil cooler, so that the air compressor temperature cannot be effectively controlled; 3 the lubricating oil with impurities passes through the temperature control valve and jams the sliding sliding core, so that The spool cannot be completely closed, and some of the oil is directly bypassed to the unit, resulting in poor cooling.
(3) The failure of the electronic control system, such as the false alarm of the temperature probe, the operation of the ultra-high temperature and strong corrosive gas caused by the malfunction of the temperature relay and the high-temperature environment of the circuit breaker, the wind cooler is susceptible to the perforation run of the hydrogen fluoride gas. At present, air cooling can only be used for 4 to 8 months, and it is not stable, which greatly increases the cost of maintenance.
2.2.2 Operation equipment analysis Electronic control system, detection equipment body failure. Too much dust enters and jams the spool. The air intake filter and the pipeline are not tightly sealed, and the air dust is excessively entered into the air compressor control system. It is found that the spools of the servo valve and the discharge valve are most likely to be stuck. The seal fails and the spool is suffocated and cannot operate normally. The compressed air produced has more water and the efficiency of water removal is reduced. The air-cooled radiator is easy to scale in the wall of the cooling pipe. Secondly, the aluminum alloy fins gather dust and sludge, and the heat dissipation effect is not good. The steam separator is faulty and cannot be drained normally. Air-cooled radiators are susceptible to corrosion and perforation and have a short service life.
3 Improvement measures Through several years of tracking and groping, it is believed that in order to adapt to the high temperature, high dust, high corrosion and humidity environment of the region, the ERC2055 air compressor runs smoothly, and several functional parts of the air compressor are improved.
Jumping and alarming; (4) Oil pressure relief valve piece falling off, oil pressure relief valve is to discharge excess lubricating oil in the stator cavity outside the cavity when the air compressor starts. If the oil pressure relief valve piece falls off, the compressed air will enter the compression chamber for secondary compression, the air compressor load will increase, and more heat will be generated. The cooling system cannot cool too much heat, and the air compressor temperature cannot be controlled.
(5) Lubrication of cooling oil failure. The lubricating oil of the air compressor not only lubricates various moving parts, such as the rotor journal and the sliding piece rotating at high speed, but also generates a large amount of thermal energy during the cooling and compression process, such as the friction heat generated by the friction pair and the high-speed motion, and the heat generated when the air is compressed. . The air to be compressed contains a large amount of dust, water and corrosive hydrogen fluoride and sulfur dioxide gas, which has a great influence on the lubricating oil and renders the lubricating oil ineffective. After the lubricating oil fails, no oil film is formed on the relative motion pair, and the relative motion friction generates heat, and the cooling effect is lowered, so that the temperature rise is too high when the air compressor is running.
2.2 Fault phenomenon 2: Air compressor operation can not be properly loaded and unloaded 2.2.1 Working environment analysis Environmental factors The air humidity to be processed is large, and contains a large amount of hydrogen fluoride corrosion gas, which is not conducive to the extension of lubrication life, the bias in compressed air The acidic condensate accelerates the corrosion of the heat exchanger and the pipeline; the components of the air compressor are not suitable for high dust, high ambient temperature and high humidity. 3.1 Adjust the temperature control valve parameters to reset and improve the temperature control bypass valve opening temperature. Within 70±10 ft, after long-term use, the probe function is reduced, and it can't operate at normal temperature point, so that the hot lubricating oil coming out from the air compressor body cannot be completely cooled by the oil cooler and returned directly to the air compressor body, making it empty. The temperature of the press can not be effectively controlled; combined with the local climatic conditions in Sichuan, the air compressor is located on the PTM crane beam, especially in summer, the minimum is 53 or more, and in winter, there are more than 30. Therefore, the temperature control bypass valve can be used in summer. The adjustment is made to be in the open state. After the summer experiment, the high temperature alarm caused by the failure of the temperature control bypass valve is solved by this method. Now five PTM crane air compressors are used for such shielding in the hot summer days, and the effect is obvious.
3.2 Improvement and improvement of the service life of air-cooled radiators Crude cold and air-cooling are integrated into one, but in the course of use, the service life of air-cooling is short, 6~12 months, which has been a prominent problem, and oil-cooled The life expectancy is much longer, more than 2 years. Therefore, in order to save the cost of spare parts, the oil cooling and air cooling are separately produced, and the air cooling is frequently replaced without moving the oil. The reason for the low air-cooling life is that, in the special environment of electrolytic aluminum, because the air contains acid gases such as hydrogen fluoride and sulfur dioxide, these gases will dissolve in the condensed water to improve the stability of the PTM crane 2055 air compressor. The study of weak acidity, the impact on heat exchangers and pipelines is mainly caused by corrosion leakage, especially aluminum slab heat exchangers. Therefore, two solutions are provided in the design of the air compressor, which is an internal anti-corrosion treatment of the aluminum squash heat exchanger, which can prolong the life of the heat exchanger and increase the life of the heat exchanger by about 1/3. . However, since the quality of the anticorrosive treatment is unstable in actual operation, the life of the heat exchanger may be degraded. The second method is to replace the compressed air heat exchanger with a corrosion-resistant material. For example, the stainless steel material can significantly increase the life of the heat exchanger. In the general design, the life of the heat exchanger is not less than 2 years, but this change The initial investment of the heat exchanger is large, and the thermal conductivity of the stainless steel material is lower than that of the aluminum alloy, and the heat exchange per unit area is low. Therefore, in order to achieve the same heat exchange effect, the stainless steel heat exchanger is large in size and cumbersome, and needs to be separately supported. A cooling fan performs heat exchange. Although this will increase the cost of input, it is necessary to improve heat exchange efficiency, improve the quality of compressed air produced, and enhance the reliability of air compressor operation.
3.3 Increase the dust holding capacity of the air intake filter and increase the automatic dust removal device. The current use of the air intake filter has a short service life and increase the daily maintenance work. The air filter element is purged daily for a period of two weeks. Suitable for use in heavy dust environments where electrolytic aluminum is used. A strict air filtration system has been chosen, but in daily maintenance it is important to ensure efficient operation of the air filtration system. According to the comparison with the air compressor of the same use as Ingersoll Rand, it was found that the Ingersoll Rand air compressor inlet filter was added with a pretreatment filter and equipped with an automatic suction dust removal device H, for example.
The automatic dust-removing device is suitable for working in a high-dust working environment of the aluminum plant. The suction port of the compressor is designed with an oversized filter element. The four-fold filter is first passed through the disc type coarse filter and then passed through a cyclone type dust-removing device equipped with an automatic suction dust-removing device. Finally, through the air filter, multiple filtration. Moreover, appropriately increasing the volume size of the filter and increasing the dust holding capacity of the filter will prolong the maintenance period of the filter system, thereby prolonging the service life of the air filter, the main engine and the oil filter.
4 Conclusions Improving the operational stability of the ERC2055 air compressor under high temperature and heavy dust and corrosive environment is the basic condition for ensuring the reliable operation of the electrolysis PTM crane. Therefore, doing the following work plays an important role in improving the stability of the air compressor: (1) Under the heavy dust environment of electrolytic aluminum, do the maintenance of the air compressor, and focus on ensuring the air filtration system. Efficient work with the lubrication system, if necessary, increase the frequency of maintenance of the air compressor.
(2) The air compressor is caused by the high temperature, the air compressor can not be loaded and unloaded normally. The fault is the most common problem of the air compressor. Use the correct detection method and judge according to the simple and difficult process and steps. , accurately handle all types of failures.
(3) In view of the operating characteristics of the ERC2055 air compressor under high temperature, high dust, high corrosion and humidity environment in the region, propose improved methods, such as adjusting the parameters of the temperature control valve, improving and improving the service life of the air-cooled radiator, and increasing The large air intake filter dust holding capacity and the addition of an automatic dust removal device will better improve the operational stability of the ERC2055 air compressor.
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