What Is an Industrial Air Compressor and Its Types?

An industrial air compressor is a mechanical apparatus utilized to generate pressure in compressible fluids or gasses, the most common being air. Compressors are used in a wide range of industrial settings to provide functions ranging from powering air tools to propelling gasses through pipelines. Closely related to pumps, compressors are usually categorized as either positive-displacement or centrifugal, also known as kinetic or dynamic compressors, respectively. Industrial compressors are available in varying sizes as well, with some variations being as compact as glovebox units used to inflate car tires or large enough to be used in pipeline services.

As air is being compressed, internal pressure will begin to exceed that of atmospheric pressure, and it is worth noting that energy is utilized to compress the air. As compressed air pushes to return to its normal state, energy is simultaneously released as the air expands, returning to its original atmospheric pressure. Moreover, air compressors compress air to high pressures; thus, it creates potential energy that can be harnessed. Unlike other sources of power, compressed air does not involve the conversion of energy from one form to another at the point of application. Instead, pneumatic or compressed air devices are characterized by a high power-to-volume or power-to-weight ratio.

Although compressed air is not as fast as electricity or as efficient as hydraulics, it is still useful in an array of applications. In fact, it is often the preferred option where costs and efficiency are a major concern. The primary advantage of compressed air is that users have more control over it, and it does not pose the same shock hazard risk that electricity does or the fire hazard that oils do. Nevertheless, safety codes and regulations for handling compressed air should be taken into consideration. It is also important to note that compressed air can be found in two forms: active air and energy air.

Active Air v. Energy Air

Active air is compressed air that comes in contact with a product. This type of air is useful in preserving food and beverages, electronics, pharmaceuticals, and chemical industries. Energy air, on the other hand, is compressed air used to transmit and store energy utilized in mechanical work; therefore, energy air is used to power pneumatic tools. Because of the differences in application, it is critical that active air quality is of higher purity than that of energy air. As such, contaminants like dust, water, and oil should always be filtered out. Meanwhile, the water used in powering a turbine or flushing a toilet does not need to be of higher quality than drinking water.

Types of Industrial Air Compressors

Air compressors that are of 30 horsepower size or smaller are considered rotary or reciprocating compressors. Reciprocating compressors or piston compressors take advantage of the reciprocating action of the piston(s) to compress the gas in the cylinder(s). After this initial stroke, the compressed air is then discharged via valves into receiving tanks at high pressure. Typically, the compressor and the tank are mounted together in a skid or frame as a packaged unit. Apart from providing compressed air as a source of energy, piston compressors can be utilized to transmit natural gas by pipeline operators. Below, we will outline some of the most common reciprocating and rotary compressors, as well as how they work.

1. Reciprocating Diaphragm Compressors

Reciprocating diaphragm compressors use an oscillating action of a flexible disc to generate pressure. Essentially, a motor-mounted concentric oscillates the disc which then expands and contracts the compression chamber volume. Diaphragm compressors are good options when contamination of the output air must be avoided in laboratory or hospital applications.

2. Reciprocating Single Acting Compressors

Reciprocating single acting compressors are designed as one-stage or two-stage compressors. Single-stage versions operate with air drawn from the atmosphere and compress it using a single stroke to its final pressure. In contrast, two-stage compressors compress air to an intermediate pressure in the first stage, and the compressed air that goes into the second stage first passes through an intercooler. The intercooler eliminates any heat generated in the first-stage cycle.

3. Reciprocating Rocking Piston Compressors

Reciprocating rocking piston compressors generate pressure through a reciprocating action of a piston and a one-piece connecting rod, and this setup ensures that the piston head can rock as it reciprocates. Additionally, the rocking piston type uses low friction, non-metallic rings and does not require lubrication to work smoothly.

4. Rotary Helical Screw Compressors

Rotary helical screw compressors are designed with two helical rotors that are intermeshed in a twin bore casing. The single-stage version of this compressor has an inlet located near the drive shaft end at the top of the cylinder. The rotors come apart at the cylinder air inlet end and draw air into the clearance between the secondary rotor grooves and the main rotor lobes. Furthermore, the rotation continues, enabling the rotor tips to pass the inlet port edges. Finally, the air is trapped in between the cavities of the rotor and the cylinder wall, and the main rotor lobes roll into the rotor grooves, the volume is reduced, and cell pressure is increased, causing compression as rotation continues.

5. Rotary Sliding Vane Compressors

Rotary sliding vane compressors are equipped with a rotor that is mounted eccentrically in a housing. Centrifugal force slides out the vanes as the rotor runs until the vanes seal against a film of lubricant coating on the stator wall. As the rotor turns in the cylinder, the volume of the sliding vanes’ space reduces, thereby compressing the air.

6. Rotary Scroll Compressors

Rotary scroll compressors compress air by interacting a fixed element and a helical element that orbits and progressively compresses the air. As this process repeats itself, users obtain pulse-free compressed air. Because this compressor type has few moving parts, very little maintenance is necessitated.

Conclusion

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