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07. What are The Advantages of Oil-injected Screw Air Compressors?

Oil-injected screw compressors have become the new mainstream in the development of air compressors today, offering superior and reliable performance. They have minimal vibration, low noise, high efficiency, and no vulnerable parts. The precise fit between the male and female rotors, as well as between the rotors and the casing, reduces gas backflow leakage and improves efficiency. The absence of cylinder reciprocating motion reduces vibration and noise. The unique lubrication method brings several advantages:

  1. The lubricating oil is continuously injected into the compression chamber and bearings due to the pressure difference generated, simplifying the complex mechanical structure.
  2. The injected lubricating oil forms an oil film between the rotors, providing lubrication and cooling effects to the equipment. The secondary rotor is directly driven by the main rotor without the need for highly precise synchronizing gears.
  3. The injected lubricating oil enhances air sealing. From an energy-saving perspective, oil-injected compressors have higher energy efficiency compared to oil-free compressors, thereby improving the volumetric efficiency of the air compressor.
  4. The lubricating oil reduces noise generated by high-frequency compression.
  5. During operation, the lubricating oil is atomized into a mist and thoroughly mixed with the hot compressed air. The oil circulates at a high speed, experiencing repeated heating and cooling cycles. The presence of moisture and corrosive gases in the air accelerates oil oxidation. Therefore, synthetic lubricating oil is commonly used as it absorbs a large amount of compression heat, keeps the exhaust temperature from becoming excessively high, and prevents friction between the rotors and the casing due to different thermal expansion coefficients.、
  6. The presence of oil and gas in compressed air can cause various operational issues. Even with precise filtration, complete oil-free conditions cannot be achieved. Although oil-injected compressors have higher energy efficiency, the use of precision filters incurs additional costs for procurement and replacement, as well as some pressure loss.

Overall, oil-injected screw compressors offer significant advantages in terms of performance, efficiency, and reliability, but the presence of oil in the compressed air requires careful consideration and proper maintenance to ensure optimal operation.

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