Air compressor safety operation technology
As a kind of power source, the application field of air compressors is more and more extensive, and it plays a vital role in the whole manufacturing. However, during the operation of the air compressor, due to the poor cooling heat transfer effect, abnormal pressure, insufficient exhaust volume, etc., the actual running time of the air compressor is short, the machine stops and starts frequently, and it is impossible to achieve efficient and safe operation. The requirements directly affect production and bring immeasurable losses to the company. Therefore, it is necessary to correctly identify the failure of the air compressor, analyze the cause, reduce the number of failures, and propose preventive measures to ensure the safe operation of the air compressor.
1 Air compressor failure type and cause analysis
1.1 Insufficient exhaust
The main performance of the shortage of exhaust gas is that the pressure does not reach the end pressure. From the fault phenomenon, it is likely to be caused by the following reasons:
First, the failure of the inlet air filter, when the fouling in the filter is blocked, the exhaust volume will be reduced; and if the suction pipe is too long and the pipe diameter is small, causing the suction resistance to increase, it will directly affect The amount of exhaust.
Second, the low speed of the air compressor will reduce the exhaust volume: the air compressor is designed according to the specified altitude, intake temperature and humidity. If it is used on the plateau exceeding the above standard, it will be As a result, the suction pressure is reduced and the displacement is also reduced. When the conveyor belt slips, the speed of the air compressor is reduced, which in turn affects the exhaust gas volume.
Thirdly, the wear of the air compressor is caused by the change of the clearance of the air compressor: the cylinder, the piston and the piston ring are seriously worn and out of tolerance, causing the relevant clearance to increase and the leakage amount to increase, which seriously affects the displacement.
Fourth, the air compressor system is seriously leaking, mainly because the stuffing box is not tight and the air leakage is reduced to reduce the gas volume. The reason is: first, the stuffing box itself is not required to be manufactured; secondly, it may be the piston rod during installation. There is no good match with the center of the stuffing box, resulting in air leakage caused by abrasion, strain and the like.
The fifth is the impact of the failure of the air compressor pressure valve on the displacement. It mainly refers to the metal fragments or other debris falling between the valve seat and the valve of the suction and exhaust valves, resulting in poor closure and leakage.
In addition, the mismatch between the spring force of the valve and the gas force will also affect the displacement. If the spring force is too strong, the valve will be opened slowly. If the spring force is too weak, the valve will not close in time. This will not only affect the displacement, but also if it is serious. It will affect the increase of power and even affect the service life of valve discs and springs.
1.2 Exhaust gas temperature is abnormal
An abnormal exhaust temperature means that it is higher than the design value, mainly due to a cooling system failure. Theoretically, the factors affecting the increase in exhaust gas temperature are: intake air temperature, pressure ratio, and compression index (for air compression index K = 1.4). The actual situation affects the factors of high suction temperature, such as: low intermediate cooling efficiency, or the scale connection in the intercooler affects heat exchange, the inhalation temperature of the latter stage must be high, and the exhaust temperature will be high. The air valve leaks and the piston ring leaks, which not only affects the rise of the exhaust gas temperature, but also changes the level pressure. As long as the pressure ratio is higher than the normal value, the exhaust gas temperature will rise. In addition, water-cooled machines, lack of water or insufficient water, will increase the temperature of the exhaust.
1.3 Extraordinary vibration and noise
If the air compressor fails in some parts, it will make an abnormal sound. Generally speaking, the operator can distinguish abnormal vibration and noise by listening to the sample. The drive motor is unstable, and the alignment of the shaft changes abnormal vibration and noise. The clearance between the piston and the cylinder head is too small and directly impacts; the piston rod and the piston connecting nut loose or trip, the piston end face is blocked, the piston moves up against the cylinder head, the metal fragments in the cylinder and the water accumulated in the cylinder, etc. Both can make a knocking sound in the cylinder. The exhaust valve piece is broken, the valve spring is soft or damaged, and the load regulator is improperly adjusted, etc., and the impact sound can be generated in the valve cavity.
1.4 Overheat fault
In the position where the crosshead and the sliding plate, the crankshaft and the bearing, the packing and the piston rod are in friction, the temperature is too high and exceeds the prescribed value, which is called overheating. The consequences of overheating: First, speed up the wear of the friction parts. Second, overheating makes a lot of heat.
Constant accumulation of direct burning of the friction surface and burning and causing a major accident in the machine. The main cause of overheating of the bearing is that the bearing and the journal are not uniformly attached or the contact area is too small; the crankshaft of the bearing is bent, the viscosity of the lubricating oil is too small, the oil passage is blocked, the oil pump is broken, and the oil is broken; There is no gap, the spindle and motor shaft are not aligned, and the two axes are tilted.
There are many reasons for the failure of the air compressor. There are both design and manufacturing reasons, as well as operation and maintenance and management reasons. Some effective solutions should be proposed through comprehensive analysis of these faults to extend the life of the air compressor.
2 Air compressor daily operation failure solution
2.1 Optimized cooling system
Abnormal temperature is the main cause of air compressor failure, so how to reduce the system temperature and maintain an efficient cooling system is essential to extend the life of the air compressor. The air compressor cooling system can be optimized from the following aspects.
Reduce the air compressor temperature by improving the ventilation conditions in the compressor room. The working environment of mechanical equipment has a greater impact on the use of mechanical equipment, reducing the temperature of the equipment, can reduce the adverse impact on the equipment. As the unit's service life increases, the unit's heat generation is also increasing. The original method of air intake from the intake duct to meet the gas production and cooling unit is no longer applicable. For example, the Hangzhou Cigarette Factory transforms the left and right side doors of the unit into the louver form of the lower inlet air, so that the ambient temperature air is drawn from the lower part of the equipment and then discharged from the upper exhaust fan, effectively reducing the unit temperature. The company's original unit cooling and exhaust gas is directly discharged into the exhaust passage, and then discharged from the roof, but the power of the unit exhaust fan is small.
The air exchange rate in the channel is not high, which causes the temperature in the channel to rise, which affects the cooling of the unit. By installing an exhaust fan at the exhaust passage opening, the air flow rate in the passage is increased, and the number of air exchanges in the passage is increased, thereby improving the cooling effect of the unit.
Avoid scaling of the cooling system. The fouling of the cooling system is the main cause of the abnormal temperature of the air compressor, which makes the cooling water unable to effectively exchange heat with the cylinder wall, resulting in an increase in the operating temperature of the cylinder and causing an accident. To solve this problem, many scholars at home and abroad have done a lot of research work and obtained some research results. Mainly by strengthening the monitoring and management of the cooling water quality, the cooling water is modified and the air compressor is cleaned regularly to avoid the scaling of the cooling system. The cleaning and descaling method for the air compressor includes mechanical descaling and chemistry. Descaling method, etc., because the structure of the cylinder water jacket is relatively complicated, the mechanical descaling method is difficult to clean, so the current descaling method is mainly based on the chemical descaling method.
2.2 Maintenance of the equipment
The basic maintenance of the air compressor includes: replacement and maintenance of the air filter; replacement of the oil filter, replacement of the air compressor oil; replacement and maintenance of the oil and gas separation core; installation and maintenance of the coupling; maintenance and maintenance of the cooler .
(1) Maintenance and maintenance of the air filter. The function of the air filter is to filter out the dust and dirt contained in the inhaled air, and send the filtered clean air to the compression chamber for compression. It is best to maintain the air filter once a week, unscrew the gland nut, take out the air filter, and use 0.2~0.4MPa compressed air to blow out the dust particles on the outer surface of the air filter from the inner cavity of the air filter. Use a clean rag. Wipe off the dirt on the inner wall of the air filter housing. Refill the air filter, pay attention to the tight seal at the front end of the air filter. The air filter should be replaced after running for 500 hours in the running-in period. Normally, it should be replaced once in 3000h. When cleaning or replacing the air filter element, the parts must be combined one by one to prevent foreign matter from falling into the intake valve.
(2) Replacement of oil filter and replacement of air compressor oil. Under normal circumstances, it is recommended to replace the new filter element every 1500~2000h. When changing the oil, it is best to replace the oil filter at the same time. The air compressor oil has a decisive influence on the performance of the air compressor. After the new machine is running for 500 hours, the first oil product is replaced. After that, the new oil is generally replaced every 3000 hours. It is best to change the oil filter at the same time when changing oil. Whether it is an oil filter or an air compressor oil, use a shortened replacement cycle in a harsh environment.
(3) Replacement and maintenance of oil and gas separation cores. Replace the split core every year or when the monitor issues a maintenance signal. The separation core can only be replaced and can not be used after cleaning.
(4) Installation and maintenance of the coupling. The coupling is related to the precision of the equipment, and the assembly error is relatively high. After the axial deviation calibration, the adjustment of the axial deviation, horizontal clearance and angular deviation calibration of the motor under the gasket can be adjusted. Install bolts and lock washers.
2.3 Specification operation
The standardized operation can improve the operating efficiency of the air compressor, reduce the number of failures, slow down the fatigue of equipment parts, and prolong the service life of the air compressor. The operation of the specification should include the following aspects.
Before starting the air compressor, please make sure that the pipeline valve is in the normal position, the air compressor panel is displayed normally, and then press the start button to start. When shutting down, please press the stop button to stop, and the air compressor will automatically unload and stop. Non-emergency conditions Do not stop by pressing the red emergency stop button.
Every 500 hours of operation of the air compressor, the electrical wiring inside the air compressor must be re-inspected and tightened. Record the main parameters of the air compressor every day, in case of failure to provide a basis for analysis and processing. Check the oil level daily to ensure that the coolant is adequate and observe the internal piping for leaks.
