A, before the operation of air compressor, should pay attention to the following questions:
1. Keep the lubricating oil in the oil pool within the scale range, and check that the oil quantity in the oiler should not be lower than the scale line value before the air compressor runs.
2. Check whether the moving parts are flexible, whether the connecting parts are fastened, whether the lubrication system is normal, and whether the motor and electrical control equipment are safe and reliable.
3. Before the air compressor runs, check whether the protective devices and safety accessories are in good condition.
4. Check whether the exhaust pipe is unblocked.
5. Connect the water source and open the inlet valve to make the cooling water flow smoothly.
Second, attention should be paid to the operation of the air compressor before it is started for the first time after being stopped for a long time, and it must be rotated to check whether there is any impact, jamming or abnormal sound.
Third, the machine must be started under no-load condition, and then gradually make the air compressor run under load after the no-load operation is normal.
Four, after the normal operation of the air compressor, should always pay attention to all kinds of instrument readings, and adjust at any time.
Five, air compressor is running, should also check the following contents:
1. Whether the motor temperature is normal, and whether the readings of all electric meters are within the specified range.
2. Whether the operation sound of each part is normal.
3. Whether the suction valve cover is hot and the valve sound is normal.
4. Whether the various safety protection devices of the air compressor are reliable.
Six, air compressor running for 2 hours, oil-water separator, intercooler, after cooler oil-water discharge once, gas tank oil-water discharge once per shift.
Seven, air compressor found in the operation of the following situations, should immediately stop, find out the reason, and be ruled out.
1. Lubricating oil or cooling water is finally cut off.
2. The water temperature suddenly rises or falls.
3. The exhaust pressure suddenly rises and the safety valve fails.
The power part of the press operation must comply with the relevant provisions of the internal combustion engine. 1. When installing the air compressor, a wide and well-lit place is needed for easy operation and maintenance.
2. The relative humidity of the air should be low and there should be less dust. The air should be clean and well ventilated, away from flammable, explosive and corrosive chemicals and harmful and unsafe articles, and away from places where dust is emitted.
3. When installing the air compressor, the ambient temperature of the installation site should be higher than 5 degrees in winter and lower than 40 degrees in summer, because the higher the ambient temperature, the higher the exhaust temperature of the air compressor, which will affect the performance of the compressor. If necessary, the installation site should be equipped with ventilation or cooling equipment.
4. If the factory environment is poor and there is a lot of dust, pre-filtration equipment must be installed.
5. The air compressor units at the air compressor installation site shall be arranged in a single row.
6. Reserve a service road, and when conditions permit, a crown block can be installed to facilitate the maintenance of air compressor equipment.
7. Reserve maintenance space, and the distance between the air compressor and the wall must be at least 70 cm.
8. The air compressor shall be at least one meter away from the headspace.
Comparison of mainstream air compressors;
Taking the piston air compressor as an example, it shows that the production of the main engine and key control components of the twin-screw air compressor is not easy, although the technology and capital threshold are high. But for users, from the analysis in the above table, it can be seen that in the application range of twin-screw air compressor, compared with the corresponding piston air compressor, the only disadvantage of twin-screw is the high purchase cost, but this can be completely compensated by the low use cost and long life hit of twin-screw air compressor. In fact, the procurement cost only accounts for a small part of the total cost.
Here is an example. If a user wants to buy a 20m/min, 0.7MPa air compressor and plans to use it for ten years, the running time is equivalent to 30,000 hours, we will design two schemes for them. See the following table: purchase cost of twin-screw air compressor piston air compressor 159000, matching power 1 10KW, power consumption of 3.3 million kwh, electricity expenditure of 3.96 million kwh (according to 1 yuan/kwh), 3.3 million yuan, 3.96 million yuan ★ electricity expenditure with excessive energy loss under partial load or no load. According to 80,000 kwh, 80,000 yuan, 6,543.8+0.6 million kwh and 6,543.8+0.6 million yuan ★★★★★★ ★ The maintenance cost is about 60,000 yuan and 40,000 yuan respectively. Generally, there is no maintenance of about 50,000 yuan ★★★★★★★ There is no total expenditure of 90,000 yuan to replace a new machine, with a total expenditure of 3,594,390 yuan and more than 800,000 yuan. If the gas consumption changes,
★★★★ If it is a belt-driven screw machine, the belt needs to be replaced.
★★★★★★★ The post-treatment device of piston air compressor has a heavy burden, which may increase the maintenance cost of the post-treatment device.
★★★★★ There is another factor to consider, that is, after the piston air compressor is used for a period of time, the displacement will be reduced due to wear and tear. If the allowance is not enough when selecting the model, it will cause insufficient gas and affect the production efficiency. Sometimes a small displacement air compressor will be added to make up for it, which is also an extra cost. The displacement of screw air compressor will never drop. In order to make the air compressor run normally and reliably, and ensure the service life of the unit, it is necessary to make a detailed maintenance plan, implement special operation, regular maintenance and regular inspection and maintenance, and keep the air compressor unit clean, oil-free and dirt-free.
Maintenance of main components is carried out with reference to the following table:
Note: A. When repairing and replacing all components according to the above table, it must be confirmed that the pressure in the air compressor system has been released and isolated from other pressure sources, the switch on the main circuit has been turned off, and a safety sign that it is not allowed to turn off has been made.
B The replacement time of compressor cooling lubricating oil depends on the use environment, humidity, dust and whether there is acid-base gas in the air. The newly purchased air compressor must be replaced with new oil after the first operation of 500 hours, and then every 4000 hours according to the normal oil change cycle, and the machine with an annual operation of less than 4000 hours should be replaced once a year.
C. The oil filter must be replaced after 300-500 hours for the first use, and every 2000 hours according to the normal time after 2000 hours for the second use.
D when repairing and replacing the air filter or air inlet valve, remember not to let any sundries fall into the main cavity of the compressor. When operating, close the host entrance. After the operation, turn it by hand several times according to the rotation direction of the main engine, and then turn it on after confirming that there are no obstacles.
E. When the machine is running, check the belt tension every 2000 hours. If the belt is loose, adjust it until the belt is tight; In order to protect the belt, it is necessary to prevent the belt from being scrapped due to oil pollution in the whole process.
F every time the oil is changed, the oil filter must be changed at the same time.
G try to replace the parts with the original parts of the company, otherwise the supplier will not be responsible for the matching problem. When the air compressor runs for about 2000 hours, in order to remove the dust on the cooling surface, it is necessary to open the cover of the cooler purge hole on the fan bracket and purge the cooler with a dust-blowing air gun until the dust on the cooling surface is completely purged. Shang Ruo's radiating surface is seriously polluted and difficult to clean. You can unload the cooler, pour out the oil in the cooler, seal the four entrances and exits to prevent dirt from entering, then blow off the dust on both sides with compressed air or rinse with water, and finally dry the water stains on the surface. Put it back in place.
Remember! Don't scrape off dirt with hard objects such as iron brush to avoid damaging the surface of radiator. The moisture in the air may condense in the oil-gas separation tank, especially in wet weather, when the exhaust temperature is lower than the pressure dew point of the air or when the machine is stopped for cooling, more condensed water will be precipitated. Excessive moisture in oil will cause emulsification of lubricating oil and affect the safe operation of the machine, and the possible reasons;
1. Poor lubrication of compressor main engine;
2. The effect of oil-gas separation becomes worse, and the pressure difference of oil-gas separator becomes larger;
3. Causes the parts to rust; Therefore, the condensed water discharge plan should be made according to the humidity. The method of discharging condensed water should be carried out after the machine is stopped, the oil-gas separation tank is pressureless, fully cooled and the condensed water is fully precipitated, such as before starting in the morning.
1, first open the air valve to eliminate air pressure.
2. Unscrew the front plug of the ball valve at the bottom of the oil-gas separation tank.
3 slowly open the ball valve to drain water until the oil flows out, and then close the ball valve.
4 Screw on the front plug of the ball valve. The safety valve has been set before the whole machine leaves the factory, and the supplier does not encourage users to adjust the safety valve privately. If adjustment is really necessary, it should be carried out under the guidance of the local labor safety department or the supplier's maintenance personnel to avoid adverse consequences.
For general users, some compressor maintenance suggestions are provided for users' reference.
(1), weekly:
A. check the device for abnormal sound and leakage.
Check whether the meter reading is correct.
C. check whether the temperature display is normal.
②. Every month:
A. check whether the machine is rusty or loose. If there is rust, remove rust, oil or paint, and tighten it loosely.
B. drain the condensed water.
(3) every three months:
A clean the dust on the outer surface of the cooler, fan cover and blades.
B. fill the motor bearing with lubricating oil.
C. check whether the hose is aged and cracked.
D. check the electrical components and clean the electrical cabinet. In the running state, the oil level of the compressor should be kept between the minimum and maximum oil level. Too much oil will affect the separation effect, and too little oil will affect the lubrication and cooling performance of the machine. During the oil change cycle, if the oil level is lower than the minimum oil level, the lubricating oil should be replenished in time. The method is as follows:
(1), stop internal pressure release (confirm that there is no pressure in the system), and pull down the main power switch.
(2) Open the oil filler on the oil-gas separation tank and add a proper amount of cooling lubricating oil.
③ For the oil change time after normal operation of the air compressor, please refer to the regular maintenance table. Long-term operation of air compressor will cause equipment to be blocked by scale, reduce efficiency, increase energy consumption and shorten service life. If the scale can not be removed in time, it will be in danger of equipment maintenance, shutdown or scrap replacement. For a long time, traditional cleaning methods, such as mechanical methods (scraping and brushing), high-pressure water and chemical cleaning (pickling), have many problems in cleaning air compressors:
Deposits such as scale cannot be completely removed, and the equipment will be corroded. Residual acid will cause secondary corrosion or under-scale corrosion of materials, which will eventually lead to the replacement of equipment. In addition, the cleaning waste liquid is toxic, and wastewater treatment needs a lot of money. Enterprises can avoid the above situation by using efficient and environmentally friendly cleaning agents, which are efficient, environmentally friendly, safe and non-corrosive. Not only the cleaning effect is good, but also the equipment is not corroded, which can ensure the long-term use of the air compressor. Air compressor noise pollution control noise is a kind of noise that people don't need. It is a public hazard that has been put on the agenda and needs to be solved urgently. There are many aspects of noise pollution, but the classification of air compressor noise pollution is low. The noise level is above 40dBA, which has different effects on sleep. Long-term exposure to noise will cause permanent deafness, which often leads to indigestion, poor spirit, nausea and vomiting, and even personal injury and death.
Air compressor is a kind of general mechanical product with large quantity and wide range, which is widely used in machinery, mining, chemical industry, construction and other departments. Its high noise level and great influence have become one of the important sources of environmental noise pollution. From production to manufacturing departments, solving the noise problem of air compressors can further improve product quality and greatly help improve people's livelihood and environmental pollution. The noise pollution of air compressor needs reasonable control, and the state has increased its investment in this area.
Noise pollution is also an important factor of environmental pollution. People living near factories or highways are more or less troubled by machinery and equipment and car noise. Taking noise pollution index as an index to assess factories and living environment has long been included in the national environmental protection standards. Then, equipment manufacturers and suppliers should also have the responsibility and obligation to reduce the noise pollution during the operation of mechanical equipment through technical means and better create a low-decibel working and living environment. 1, air compressor should be parked away from steam, gas and dust. The air inlet pipe shall be equipped with a filtering device. After the air compressor is in place, it should be wedged symmetrically with a cushion block.
2. Always keep the outside of the storage tank clean. Welding or hot working near the gas storage tank is prohibited. The gas storage tank is subjected to water pressure test once a year, and the test pressure is 1.5 times the working pressure. The barometer and safety valve should be checked once a year.
3, the operator should be specially trained, must fully understand the structure, performance and function of air compressor and ancillary equipment, familiar with the operation and maintenance procedures.
4, the operator should wear work clothes, lesbians should be woven into a work hat. It is strictly forbidden to operate after drinking, do not engage in anything unrelated to the operation, do not leave the post without authorization, and do not decide to replace the work by non-local operators without authorization.
5. Before starting the air compressor, do a good job of inspection and preparation according to regulations, and pay attention to opening all valves of the air storage tank. After the diesel engine is started, it must be heated at low speed, medium speed and rated speed. Pay attention to whether the readings of various instruments are normal before operating with load. When the air compressor is started, the load should be gradually increased, and all components can run at full load only after they are normal.
6. During the operation of the air compressor, always pay attention to the readings of the instrument (especially the readings of the barometer) and listen to the voices of various departments. If any abnormality is found, stop the machine immediately for inspection. The maximum atmospheric pressure in the gas tank shall not exceed the pressure specified on the nameplate. Every 2 ~ 4h, open the condensate drain valve of intercooler and gas storage tank 1 ~ 2 times. Do a good job of cleaning machines. After the air compressor has been running for a long time, it is forbidden to wash it with cold water.
7. When the air compressor stops, the exhaust valve of the air storage tank should be opened gradually, and the pressure should be reduced slowly, and the speed of the diesel engine should be reduced accordingly, so that the air compressor can run at a low speed without load for 5 ~ 10 seconds. After the air compressor stops running, the diesel engine continues to run at a low speed for 5 seconds and then stops. When the temperature is below 5 degrees in winter, the cooling water without antifreeze should be discharged after shutdown.
8. When cleaning the radiator, it is forbidden to use combustion method to remove oil pollution from the pipeline. Maintenance work such as cleaning and fastening must be carried out after shutdown. When blowing parts with compressed air, it is forbidden to aim the tuyere at human body or other equipment to prevent injury and damage.
9. Regularly (weekly) conduct manual exhaust test on the safety valve of the gas storage tank to ensure the safety and effectiveness of the safety valve.
10, do a good job of cleaning the machine. After the air compressor has been running for a long time, it is forbidden to wash it with cold water. Air compressor displacement refers to the amount of air discharged by the air compressor in a unit time, which is converted into a suction state.
influencing factor
1. Leakage: There is no contact between the rotors of the air compressor and between the rotors and the casing during operation, and there will be a certain gap, so gas leakage will occur.
2. Rotational speed: The displacement of the air compressor is directly proportional to the rotational speed. The rotational speed often varies with the voltage and frequency of the power grid.
3. Suction state: In a general positive displacement air compressor, the suction amount remains unchanged. When the suction temperature rises, or the suction pressure decreases due to the excessive resistance of the suction pipe, the density of the gas decreases, which will correspondingly reduce the mass displacement of the gas.
4. Cooling effect: The temperature of the gas will increase during compression, and the temperature of the rotor and casing of the air compressor will also increase accordingly. Therefore, in the process of inhalation, the gas will be heated by the rotor and casing and expand, so the inhalation volume will be reduced accordingly.
how to improve
In order to improve the displacement of air compressor, that is, improve the output coefficient, the following methods are usually adopted:
1. Clean the cylinder and other parts if necessary.
2. Correct selection of clearance volume;
3. Adopt advanced cooling system;
4. Keep the piston ring tight;
5. Reduce the resistance when inhaling gas;
6. Keep the air valve and stuffing box sealed;
7. Maintain the sensitivity of suction valve and exhaust valve;
8. Dry and cold gas should be inhaled;
9. Properly increase the speed of air compressor;
10. Keep the output pipeline, air valve, air storage tank and cooler sealed; Pressure parameter matching
Working air pressure control: that is, how much air pressure is needed when working. Most air compressors used in the laboratory have adjustable air pressure of 0-8 bar (about 0-8 kg), which meets the air pressure requirements of experimental equipment. Stable continuous displacement (usually expressed in L/MIN): refers to the number of liters of gas flow per minute under rated working pressure, which needs to ensure the continuous stability of gas flow, so the working stability of air compressor is highly required.
Compressed air quality
Oil-free air compressor is the first choice: the material of oil-free air compressor itself does not contain oily substances, so it is not necessary to add any lubricating oil when working, so the quality of discharged air is greatly improved and the safety of supporting equipment required by users is also guaranteed. Different from the oil-free air compressor, the discharged gas contains a lot of oil molecules, which will bring different degrees of corrosion to users' supporting equipment, so it is necessary to choose an oil-free silent air compressor to ensure air quality. After installing the air filtration device, the air quality should reach the following international standard values.
The selection of air compressor is mainly based on the working pressure and flow rate of pneumatic system.
The working pressure of air source should be about 20% higher than the highest working pressure in pneumatic system, because the loss along the pipeline and local loss should be considered. If the working pressure of some parts of the system is low, a pressure reducing valve can be used to supply air. The rated discharge pressure of air compressor is divided into low pressure (0.7~ 1.0MPa), medium pressure (1.0~ 10MPa), high pressure (100MPa) and ultrahigh pressure (100 MPa or above). The common service pressure is generally 0.7- 1.25. First of all, according to the characteristics of air compressor, choose the type of air compressor.
Then, according to the working pressure and flow required by the pneumatic system, the output pressure pc and suction flow qc of the air compressor are determined, and finally the model of the air compressor is selected. pc=p+∑△p
Pc: output pressure of air compressor.
P: The maximum working pressure in pneumatic actuators.
∑△p: total pressure loss of pneumatic system.
In general, the other ∑△p=0. 15~0.2MPa. Without gas storage tank, qb=qmax.
Set the gas storage tank, qb=qsa.
Qb: Flow provided by pneumatic system.
Qmax: Maximum air consumption of pneumatic system
Qsa: Average gas consumption of pneumatic system.
Suction flow of air compressor, qc=kqb.
Qc: Suction flow of air compressor.
K: correction coefficient. This paper mainly considers the leakage of pneumatic components and pipeline joints, the estimation error of gas consumption of pneumatic system, the utilization rate of multiple pneumatic devices used at different times and the possibility of adding new pneumatic devices. Generally, k =1.5 ~ 2.0.p = (n+1) * k * p1* QC * (PC/p1) {[(k-1)/[