Types of process compressors: centrifugal vs reciprocating vs rotary screw
06.17.25
If all process compressors have the same general function, is any style suitable for every application? …No.
If you’re choosing a for your refinery, medical facility, factory or any other industry, it’s important to choose the most relevant design for your needs. There are a few to choose from, so let’s take a closer look…
What is a process compressor?
In a nutshell, a process compressor is a machine used to compress gases or vapours for industrial use. The goal is to make the gas or vapour more efficient to store, transport or to enable/speed up chemical reactions.
Different types of process compressors
Although the basic goal of all process compressors is the same, there are three main designs that compress gas in different ways: centrifugal compressors, reciprocating compressors, and rotary screw compressors.
Centrifugal compressors
These types of compressors deploy Bernoulli’s principle which states the total energy of a fluid or gas always stays the same: the sum of potential energy + kinetic energy + pressure energy.
After the gas enters the system via the inlet, the high-speed rotating blades of a centrifugal compressor increase the kinetic energy of the gas by accelerating it outwards. Once the gas leaves the impellor and enters the diffuser, it is slowed and the volume reduced. In this way, the kinetic energy is transferred to pressure energy and the pressurised gas exits to be used as desired.
Centrifugal compressors are efficient and able to compress large volumes of gas. They are used at sites and in scenarios such as:
- Oil refineries
- Natural gas operations (e.g. for transportation, storage and reinjection)
- Air compression for air supply systems
- Refrigeration
- Chemical industries to facilitate chemical reactions
Reciprocating compressors
The second type of compressor makes use of Boyles law: the pressure of a gas is inversely proportional to its volume, assuming the temperature and amount of gas are constant.
Reciprocating compressors are also referred to as piston compressors because they use pistons to compress the gas and increase its pressure. The piston moves down, drawing gas into the cylinder through an open valve. As the piston moves back up, the valve closes, the cylinder’s volume is reduced, and the gas is compressed.
This style of process compressor is favoured in situations where highly pressurised gas is required e.g.:
- Vehicle air brakes
- Powering pneumatic tools, jackhammers and drills
- Refrigeration
- Air conditioning
- Petroleum industry e.g. compressing gas at refineries
- Medical industry e.g. for precision tools in dentistry
- Aircraft pneumatic systems e.g. door operation, brakes, landing gear
Rotary screw compressors
The final main type of process compressor is rotary screw, so-called because it works by a pair of screws rotating in opposite directions. Gas is drawn in and compressed as the space between the rotors and casing gets smaller.
This type of process compressor is favoured where a continuous supply of compressed gas is needed e.g.:
- Oil and gas industry e.g. compressing gases for refining
- Car assembly lines including spray painting and tyre inflation
- Food and drink industry e.g. bottling and packaging
- Refrigeration
- Medical industry e.g. for dental tools
Get in touch
While the goal of all process compressors is similar, it’s interesting to compare the methods deployed by different models. Understanding how they function helps determine the correct style for your application, and we hope this guide has helped if you’re considering your options.
At Rochem we specialise in and for centrifugal, and axial process compressors. The efficiency and reliability of your equipment is vital to your business, and we’d be delighted to discuss how we can help.
