Methods Of Compressed Air Generation

What does a compressor do?

A compressor uses atmospheric air and reduces it to a high-pressure potential via supply of mechanical energy. The entrapped air molecules are pushed together by reducing the space which forms compressed air. The main types of compressed air generation are positive displacement, specifically rotary screw and piston type air compressors.

 

The main types of compressors

Rotary screw compressors are the second most important category of compressors apart from the piston type.

Rotary Screw Type

Rotary Screw compressors are fitted with two spindle-shaped, inter-meshing rotors.The Main rotor converts approximately 85-90 % of the energy absorbed.

The auxiliary rotor ensures the sealing of the clearance (working space) between suction and the pressure side.

During this compressed air generation process, the continued rotation of the rotor causes the Opening intake to close, as this volume is reduced the pressure increases. As this happens oil is injected into the system for lubrication, sealing and heat dissipation purposes.

Operating Principles

• Air enters through the inlet opening. The Threaded gaps of the rotors are filled with the air.
• When the rotor turns past the inlet opening they form a closed compression space between the thread gaps and the housing. This decreases in size due to the counter-rotating movement of the rotors, and the enclosed air is compressed. This compression continues until the compression space, which keeps decreasing in size , reaches the outside edge of the discharge port
• The compressed air flows out.

Types of Screw Compressors

1. Oil Injected (Single-stage compression)
2. Dry (Single and 2-stage compression)
3. Water-Injected (Single-stage compression)

See the Field Air Compressors range of Oil Injected Rotary Screw Air Compressors

Piston Type

Piston compressors fall under the category of reciprocating compressors for oil lubricated or oil free compression.

Operating Principles

• Single stage Piston compressor – The suction air is compressed directly to the highest pressure in the same cylinder. This design may be advantages when mainly low pressure is required.
• Two-Stage Piston Compressor – In the first stage the air is compressed to pressure and in most cases, is equal to the square root value of the absolute final pressure. An intermediate cooler, which causes a reduction in volume of the compressed air, is installed between the first and second stage.
• Double-Acting Piston Compressor – Cylinders on these types of compressor are double acting – the air is compressed twice per revolution and stage (double – acting).

Piston compressors consist of a crankcase, crankshaft, connecting rod (side rod), cylinder, piston, suction and pressure valve.

Types of Piston Compressors

1. Single- Stage Compression (Only one compression chamber available).
2. 2-Stage/Multi stage Compression (Several compression Chambers are connected in series)
3. Double-Acting compression (The compression chambers below and above the piston of each cylinder are used).

See the Field Air Compressors range of Reciprocating Piston Compressors

About Field Air Compressors

Field Air compressors (Pty) Ltd. Was officially established in 1992. We are a company based on family values with over 20-years’ experience in the compressed air industry. We offer many products, specializing in air compressors of most brands. We offer servicing, maintenance, and spares for all types of compressors, as well as hire out units as required. We distribute Chicago Pneumatic Air compressors and air tools. Our sales team offer friendly service and we have an experienced technical team to offer you any technical advice when required.