Key components of a process compressor and their functions

There are several different types of process compressors, but they all have the same general function: to compress gas/vapours for onward use. Different parts of process compressors play different roles, and today we explore these key components to help you better understand these essential machines.

Process compressor parts

Compressor casing

Think of this as the house for your process compressor, forming a protective barrier between the internal workings and the outside world. Robust enough to cope with internal loads, the outer periphery of the casing is unlikely to be under full pressure (although in some compressors it does act as pressure containment).

Rotor assembly

In centrifugal compressors you’ll find the shaft and impellors; screw compressors feature screws. In these types of compressors, rotational energy increases gas pressure. Find out more about how different process compressors work here.

Impellors or other compression elements

Centrifugal compressors may have multiple stages of impellors to increase the gas’s velocity. The helical, screw-shaped rotors of screw compressors increase gas pressure by reducing its volume. Meanwhile reciprocating compressors make use of pistons to compress the gas.

Diffusers

If your compressor works using continuous flow e.g. centrifugal or axial compressors, the idea is that kinetic energy is imparted to the gas, which is then converted to pressure energy. Diffusers make use of Bernoulli’s principle which states when the velocity of a gas decreases, its pressure increases. Diffusers are often gradually widening channels which cause the velocity of the gas to decrease and thus the pressure increases.

Volutes

These stable, pressurised process compressor parts act as collection chambers, ready to guide the pressurised gas to its next stage.

Bearings

Moving away from the compressor parts involved in actual gas compressions, bearings are essential elements providing support and stability. Specific to compressor type, bearings are used to:

• Minimise friction between moving parts
• Maintain shaft position
• Act as shock absorbers: transferring vibrations/loads to the casing

Seals

Effective seals are essential to prevent pressurised gas escaping the system, leaking into the atmosphere or into other sections of the machine.

Intercoolers/aftercoolers

As pressure increases, heat is generated. It’s important to manage the temperature to:

• Maintain efficient compression (the higher the gas temperature, the lower its density and more effort and expense must go into compressing it).
• Protect equipment from heat damage.

Intercoolers are placed between compressor stages, while aftercoolers are after the final stage, cooling gas before it’s delivered to its process/stored.

Suction and discharge nozzles

These nozzles are how the gas gets in and eventually out of the compressor. Thay are often fitted with flow controlling elements.

Lube oil and seal support

Bearings and seals need lubricating and/or cooling to remain functional. Your process compressor may feature oil reservoirs, pumps and filtration systems to support the main mechanism.

Controls and supporting instruments

Process compressors are finely tuned and feature monitors to track pressure, temperature, flow and vibration. This information can be used to control the systems, avoiding problems and maintaining efficiency.

A great example of this is if you get readings of increased vibrations, reduced flow and/or higher than expected temperatures, you should suspect fouling and investigate accordingly.

Get in touch

Hopefully this guide has provided a useful introduction to the distinct and essential process compressor parts.

At Rochem, we specialise in equipment and chemicals for process compressor cleaning. If you’re responsible for an axial or centrifugal process compressor, our industry-leading products can help you regain efficiency and prolong the life of your equipment. If you’ve got any questions or would like to talk about our products, please get in touch with our knowledgeable team.