Today, in many industries—including oil and gas, petrochemical, food, pharmaceutical, steel, and mining—compressed air is widely used as a cost-effective energy source for driving production line machinery or for supplying industrial gases such as oxygen and nitrogen.
To generate this economical form of energy, a device known as a compressor is employed.
Classification of Compressors
Compressors are generally classified into two main categories based on their operating principles:
1. Positive Displacement Compressors
This category includes piston, rotary vane, and screw compressors, in which a fixed volume of air is trapped and subsequently compressed.
2. Dynamic Compressors
Such as centrifugal and axial compressors, where pressure is increased by accelerating the air to a high velocity and then converting this velocity into pressure through rapid deceleration.
In medium- and large-scale industrial applications, screw compressors are the most widely used type among positive displacement compressors due to their high efficiency, low noise level, and continuous-duty capability. The following sections explain the operating principle of oil-injected screw compressors.
Oil-Injected Screw Compressor and Its Operating Principle
Oil-injected screw compressors are among the most commonly used industrial compressors and are extensively applied in industries such as mining, petrochemical processing, automotive manufacturing, pharmaceuticals, and food production.
In these compressors, oil plays a critical role in cooling, lubrication, and sealing of the compression chamber, significantly enhancing component lifespan and overall system efficiency.
Structure and Operation of an Oil-Injected Screw Compressor
The core component of an oil-injected screw compressor is the airend, which consists of two precisely machined male and female helical rotors operating within a close-tolerance housing and immersed in oil.
During the loaded (on-load) operating mode, the air inlet or unloader valve opens, allowing ambient air to pass through the intake filter and enter the airend. As the male and female rotors rotate synchronously, air is trapped between the rotor lobes. The continuous reduction in volume between the rotors results in a gradual increase in air pressure until the desired discharge pressure is achieved.
The compressed air, containing oil particles, is then directed through high-pressure piping to the oil–air separator tank. In this vessel, primary separation occurs, removing the majority of the oil from the compressed air. The residual oil content in the outlet air typically ranges between 8 and 15 ppm, which is further reduced by a high-efficiency separator filter.
Cooling and Oil Recirculation System
After separation, the compressed air flows to the aftercooler (air radiator), where its temperature is reduced before being supplied to downstream equipment and applications.
Simultaneously, the separated oil passes through an oil filter for purification and then through an oil cooler to reduce its temperature. The cooled oil is subsequently returned to the airend by natural suction, completing the lubrication and cooling cycle.
This continuous circulation ensures stable operating temperatures and reliable long-term performance of the compressor under demanding industrial conditions.
Advantages of Oil-Injected Screw Compressors
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High efficiency and stable compressed air output
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Low wear rate and extended service life
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Continuous operation capability in heavy-duty industrial environments
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Lower noise levels compared to piston compressors
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Predictable, straightforward maintenance requirements
Conclusion and Fidar Faraz Fartak Recommendation
When selecting an oil-injected screw compressor, critical factors include electric motor power, power transmission system (direct drive or belt-driven), airend quality, and the brand and reliability of consumable components.
Leveraging advanced technical expertise, an experienced engineering team, and compliance with international standards, Fidar Faraz Fartak designs and manufactures oil-injected screw compressors tailored to customer-specific operational requirements.
For professional consultation, pricing inquiries, and further technical information, please contact our technical specialists through the provided communication channels.
info@fidarcompressor.com