Screw Compressor Explained: How Does This Technology Work?

These days, everyone can find compressed air almost everywhere – in houses, commercial establishments, and factories around the world. This is mainly because compressed air has so many uses and serves a variety of industries. With plenty of uses for compressed air, it comes as no surprise that there are also numerous different types of compressors. A compressor is basically a mechanical device that is utilised to compress air or other gases to pressures that are beyond the atmospheric pressure. In other words, it increases the pressure by minimising the volume of gas or air.

One of the most common types of air compressors used across various industries is the rotary screw air compressor, or simply “screw compressor.” It is essentially a kind of air compressor that makes use of a rotary-type positive mechanism. When the application needs continuous air demand, a screw compressor is the best option. To learn more about this technology, read on as this article explains what exactly a screw compressor is and how it works.

What is a Screw Compressor?

As mentioned earlier, a screw compressor is a common type of air compressor that utilises a rotary-type positive mechanism. It is one of the two kinds of positive displacement air compressors, and it basically makes use of two rotors to create the pressure necessary for air compression. Screw compressors are considered one of the easiest kinds of air compressors to use and maintain, and they can be commonly found where big volumes of high-pressure air are needed.

The screw element of a rotary screw air compressor was developed in the 1930s and consists of two components: a male rotor and a female rotor. In oil-injected screw compressors, the male rotor essentially drives the female rotor. On the other hand, in oil-free compressors, both rotors are driven by a timing gear. These rotors operate in close proximity to ensure smooth cooperation during their use.

How Does a Screw Compressor Work?

As explained previously, a screw compressor functions with a male and female rotor rotating in opposite directions. This movement draws in air, which is then compressed as the space between the rotors and their housing is reduced. Subsequently, the compressed air is expelled through the outlet. Every screw element has an established, built-in pressure ratio that is determined by the length and pitch of the screw, as well as the shape of the discharge port.

To achieve optimal efficiency, the built-in pressure ratio must be aligned with the required working pressure. The rotor speed is optimised to a specific level to minimise mechanical losses from heat at high speeds and volumetric losses from air losses at low speeds.

Some Vital Parts of a Screw Compressor

Like water pumps and other common industrial technologies, a screw compressor comes with several components that are vital for its smooth and effective operation. When buying a rotary screw air compressor, it is very important to know the essential components of this technology to ensure that you purchase a well-functioning device. Here are some of the most vital parts of a screw compressor:

• Rotary Screw Element: This component forces the air towards the outlet and generates pressure.
• Inlet Suction Air Filter: This component is positioned at the inlet of the compressor chamber. It captures and reduces dust and the entry of harmful particles. This is essential for cleaning and protecting the compressor stages.
• Compression Chamber: This component encases the rotary screw element. Keep in mind that it is possible to utilise multiple stages for increased pressurisation.
• Oil Filter: This component eliminates dirt and contaminants from the oil used for compression or lubrication within the oil system.
• Suction Valve: The compressing unit is usually positioned at the top. The rotary screw element handles the incoming raw air. If the system pressure is too low, it fully opens. Conversely, if the pressure is too high, it closes the valves.
• Discharge Valve: This component is usually positioned at the end of the compression process. It opens upon reaching the correct pressure and ensures sufficient pressure is maintained for proper lubrication of the compression stages.
• Compressor Motor: This component powers the rotary screws and drives the compression cycle of the unit, with the compressor microprocessor controller managing its operation.
• System Control: This component appears as a display and input panel, which is essential for operating, automating, and monitoring the compressor unit.
• Separator Vessel: This tank sifts out oil from the compressed air, serves as an oil reservoir, and maintains air pressure in the system with the help of a pressure valve.
• After Cooler: This device cools the compressed air and dissipates the heat produced during the compression process. The coolers can be either air-cooled or water-cooled. You can choose between air cooling and water cooling based on your specific needs and the installation location.
• Water Separator: The water separator is a crucial component of a screw air compressor. It is positioned after the aftercooler to eliminate liquid moisture from the compressed air, thereby ensuring that the air exiting the compressor is entirely free of any liquid water.

Conclusion

Rotary screw air compressors are undoubtedly one of the most common and useful types of air compressors out there. This type of compressor uses a rotary-type positive mechanism that makes it ideal for continuous air demand. Like any other industrial technology, screw compressors have various parts that are essential for their effective and efficient operation. Each of these components plays a vital role in ensuring that the compressor operates smoothly and effectively, thereby making screw compressors a reliable choice for high-pressure air needs. When purchasing an air compressor, be sure to seek professional advice to make sure you are getting the device that meets your requirements.