At present Oil free air compressor It is improved and developed on the basis of oil air compressor. It mainly adopts two ways: one is to replace oil with water, and the other is to coat the rotor with self-lubricating coating. Because the bearings at both ends of the rotor at high speed need oil lubrication, it is necessary to seal the lubrication space of the rotor bearing and the compression space of the rotor, It is precisely because of this high-speed seal that the processing accuracy of oil-free air compressor is quite high and the cost is very high. And there is a huge problem that even the best technical seal will be damaged. Once the main engine head of oil-free air compressor fails, because it is too precise, the main engine head can only be returned to the manufacturer for maintenance, greatly increasing the irreparability, even if it can be repaired, It needs to pay a huge amount of money and a lot of maintenance time. Therefore, if it is not a super large enterprise, it is better not to blindly purchase oil-free air compressor.
Oil and no oil in the air compressor generally refer to the oil content of the gas discharged from the exhaust port of the air compressor. Generally, the oil content of the oil compressor is relatively high, and the oil content of the oil-free compressor is 0.01ppm, so this oil content is used to distinguish the oil and no oil in the air compressor. There is also an oil free air compressor, which uses resin materials instead of oil lubrication, Therefore, the final discharged gas without oil is called totally oil-free air compressor, but the quality of this kind of air compressor is not very satisfactory at present, and the domestic general is oil-free machine with oil lubrication.
The air in the air tank of the air compressor occupies a certain space, but it has no fixed shape and volume. When pressure is applied to the air in the closed container, the volume of air is compressed to increase the internal pressure. When the external force is withdrawn, the air will return to its original volume under the action of the internal pressure. If there is a movable object in the container, when the air returns to its original volume, the object will be pushed out by the pressure of the air in the container. This principle is widely used in production and life. For example, when compressed air is injected into the ball, the more sufficient the air, the harder the ball will be; When compressed air is injected into the tire, the tire can bear a certain weight. On large cars, use compressed air to open and close doors and brakes; The hydraulic press uses compressed air to pressurize water. In the factory, the compressed air is used to drive the air hammer to strike iron; In coal mines, it can use pneumatic picks to drill holes. Compressed air is also used for pipeline transportation of liquid and granular objects.
Compressed air is the second largest power energy after electricity, and it is also a process gas source with multiple uses. Its application scope covers petroleum, chemical industry, metallurgy, electricity, machinery, light industry, textile, automobile manufacturing, electronics, food, medicine, biochemistry, national defense, scientific research and other industries and departments. What is not ideal is that the compressed air contains a considerable amount of impurities, mainly including: solid particles - in a typical urban environment, there are about 140 million particles per cubic meter of air, about 80% of which are smaller than 2 μ m in size, and the suction filter of the air compressor cannot eliminate them. In addition, wear debris, rust residue and oil carbide will be constantly generated inside the air compressor system, which will accelerate the wear of gas equipment, leading to seal failure; Moisture -- The relative humidity in the atmosphere is generally higher than 65%. After compression and condensation, it becomes wet saturated air and carries a large number of liquid water droplets. They are the root cause of corrosion of equipment, pipes and valves. Ice can also block the small holes in the pneumatic system in winter. It is worth noting that even if it is separated from pure saturated air, condensate will still be separated with the decrease of temperature. Every 10 ℃ decrease, its saturated water content will decrease by 50%, that is, half of the water vapor will be converted into liquid water droplets (see Table 1). Therefore, it is necessary to adopt multi-stage separation and filtration devices in the compressed air system or pretreat the compressed air into dry air with a certain relative humidity; Oil -- lubricating oil can be used to lubricate, seal and cool the high-speed and high-temperature air compressor, but it pollutes the compressed air. The low oil machine, semi oil-free machine and all oil-free machine developed with self-lubricating materials have reduced the oil content in the compressed air, but they also have the side effects of reducing the service life of vulnerable parts, rusting of the machine interior and pipeline system, and increasing the oil content of the air compressor in the running in period, wear period and load reduction period. This is undoubtedly a threat to the pursuit of high reliability of automated production lines.
In addition, it should also be emphasized that the oil brought to the system from the air compressor is not beneficial under any circumstances. Because after several times of high-temperature oxidation and condensation emulsification, the performance of the oil has been greatly reduced, and it is acidic, which not only does not play a role in lubrication for subsequent equipment, but will damage normal lubrication; Microorganism -- In the process of pharmacy, bioengineering, food manufacturing and packaging, the contamination of bacteria and bacteriophages cannot be ignored. (Shanghai Purdue Compressor Co., Ltd.)
