What is a Screw Compressor? Components, Working, Advantages, Disadvantages

What is a Screw Compressor?

A screw compressor is a type of positive displacement compressor that uses two interlocking rotors to compress air.

Major Components of Screw Compressor

Here are the main components of a screw compressor:

1. Rotor set: The rotor set is the heart of the screw compressor. It consists of two rotors that interlock and rotate inside the compressor housing. One rotor is known as the male rotor, and the other is known as the female rotor. The male rotor has helical lobes that mesh with the female rotor, which has corresponding grooves.
2. Compressor housing: The compressor housing encloses the rotor set and provides a space for the compressed air to accumulate. The housing is typically made of cast iron or aluminum and has inlet and outlet ports for the air.
3. Inlet filter: The inlet filter removes contaminants and debris from the air before it enters the compressor. This helps to protect the compressor from damage and prolong its lifespan.
4. Oil separator: Screw compressors typically require oil to lubricate the rotors and reduce friction. The oil separator removes oil from the compressed air before it leaves the compressor.
5. Control system: The control system manages the operation of the compressor, including starting and stopping the motor, adjusting the speed of the rotors, and monitoring various parameters such as temperature and pressure.
6. Drive system: The drive system provides power to the compressor and typically consists of an electric motor and a coupling or belt drive.

Working of Screw Compressor

A screw compressor works on the principle of positive displacement. It consists of two interlocking rotors, known as the male and female rotors, that rotate in opposite directions inside a housing. As the rotors turn, the air is drawn in through the inlet and trapped between the rotors and the housing. The air is then compressed as the rotors continue to rotate, and is discharged through the outlet.

Fig. 1: Screw Compressor

Advantages of Screw Compressor

1. High efficiency: Screw compressors are known for their high efficiency and can operate at up to 90% efficiency.
2. Low noise levels: Screw compressors operate at relatively low noise levels, making them ideal for use in noise-sensitive environments.
3. Low maintenance requirements: Screw compressors have fewer moving parts than other types of compressors, resulting in lower maintenance requirements and costs.
4. High reliability: Screw compressors are known for their high reliability and can operate continuously for long periods of time.

Disadvantages of Screw Compressor

1. High initial cost: Screw compressors tend to have a higher initial cost than other types of compressors.
2. Limited pressure range: Screw compressors are generally not suitable for high-pressure applications, as they have a limited pressure range compared to other types of compressors.
3. Sensitivity to dirt and contaminants: Screw compressors are sensitive to dirt and contaminants, which can cause damage to the rotors and reduce efficiency.
4. Limited turndown ratio: Screw compressors have a limited turndown ratio, which means they may not be as efficient at lower loads as other types of compressors.

Applications of Screw Compressor

Screw compressors are widely used in various industries for a range of applications, including:

1. Manufacturing: Screw compressors are used in manufacturing processes such as metalworking, plastic molding, and food processing, where compressed air is used to power tools, machinery, and equipment.
2. Oil and gas: Screw compressors are used in the oil and gas industry for a variety of applications, including drilling, well stimulation, and gas processing.
3. Chemical and petrochemical: Screw compressors are used in the chemical and petrochemical industries for processes such as gas separation, refrigeration, and air compression.
4. Power generation: Screw compressors are used in power generation for applications such as turbine air injection, combustion air supply, and cooling.
5. Automotive: Screw compressors are used in the automotive industry for applications such as air conditioning, pneumatic tools, and paint spraying.
6. Construction: Screw compressors are used in the construction industry for applications such as sandblasting, jackhammering, and concrete spraying.