2-8 What are the characteristics of oil-injected screw air compressors?
Oil-injected screw air compressors offer efficient, reliable performance with low vibration and noise. Lubricating oil cools, lubricates, and increases airtightness, improving volumetric efficiency. Oil reduces noise and absorbs heat, but can cause issues. Precision filters can't fully remove oil, leading to additional costs and pressure loss.
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Answer: Oil-injected screw air compressors have become the new mainstream of air compressor development today. They have superior and reliable performance, low vibration, low noise, high efficiency, and no vulnerable parts. The precise matching between the yin and yang rotors and between the rotors and the housing reduces gas backflow leakage and improves efficiency; There is only mutual meshing of the rotors, no reciprocating motion of the cylinders, which reduces the source of vibration and noise; The unique lubrication method brings many advantages:
(1) Relying on the pressure difference generated by itself, lubricating oil is continuously injected into the compression chamber and bearings, simplifying the complex mechanical structure.
(2) The injected lubricating oil can form an oil film between the rotors, which has the effect of lubricating and cooling the equipment. The auxiliary rotor can be directly driven by the main rotor without the help of high-precision synchronous gears.
(3) The injected lubricating oil can increase the airtightness. It is used to improve the volumetric efficiency of the air compressor. From the perspective of energy saving, the energy efficiency of oil-type air compressors is definitely higher than that of oil-free air compressors.
(4) Lubricating oil can reduce the noise caused by high-frequency compression.
(5) During the use of the air compressor, the oil supply is in the form of mist and is fully mixed with the high-temperature compressed gas. The lubricating oil is repeatedly heated and cooled at a very high circulation speed. At the same time, the water vapor and corrosive gases in the air accelerate the oxidation and deterioration of the oil. Therefore, synthetic lubricating oil is often used, which can not only absorb a large amount of compression heat, but also prevent the exhaust temperature from being too high, and there will be no friction between the rotor and the casing due to different thermal expansion coefficients.
(6) The oil and gas in the compressed air will cause many problems in use. Even after being processed by a precision filter, it is impossible to achieve a completely oil-free state. Although the energy efficiency of oil-containing air compressors is higher, the precision filter will generate additional purchase and replacement costs and a certain amount of pressure loss.
