Centrifugal Air Compressors Basics

Centrifugal compressors technology is one of the most reliable and efficient compressed air solutions in many industries. At the heart of the centrifugal air compressor is the impeller. Every compressor unit is optimized for a given power range, with each pressure variant having an individually designed impeller. The centrifugal air compressor impeller is built to last, making these compressor units highly reliable. 

Centrifugal air compressors are used in many industrial applications. Some of the sectors that rely heavily on centrifugal air compressors include:

• Automotive
• Food and beverage
• Parma
• Power and renewable energy
• Wastewater treatment
• Oil and gas

From this article, you will learn more about centrifugal air compressor basics. Read on. 

What Is a Centrifugal Air Compressor?

A centrifugal air compressor is one of the dynamic compressors with a radial design. Unlike positive displacement air compressors, such as screw compressors and vane compressors, centrifugal air compressors operate at a constant pressure. Additionally, centrifugal compressor performance is affected by external factors, such as temperature change at the inlet valve. 

How Does Centrifugal Compressors Work?

Centrifugal air compressors working principle is as follows:

The rotating impellers draw air into the center of the impeller through the cation of centrifugal force. The radial air movement results in a pressure rise and the creation of kinetic energy. The kinetic energy is then converted into pressure as the air passes through a centrifugal air compressor diffuser and volute. 

Each compression stage results in pressure rise. Multiple stages may be required to achieve the desired pressure, depending on the application requirements. The oil and gas industry is known to use this kind of centrifugal compressor arrangement to achieve very high pressure. Accordingly, wastewater treatment requires low pressure, and therefore a single-stage arrangement is sufficient to achieve the desired pressure ratio. 

Modern centrifugal compressor configurations have ultra-speed electric motors used to drive the impellers. The design results in a compact unit without a gearbox and oil-lubrication system. Therefore, current centrifugal air compressors are oil-free. 

What Are Types of a Centrifugal Air Compressor?

Centrifugal air compressors can be found in different designs and configurations. However, the most popular centrifugal air compressor types are:

• Single-stage centrifugal air compressors
• Multi-stage centrifugal air compressors

It is important to understand that these compressors follow the same working principle. However, they only differ in their construction and how they achieve compression. Here is an overview of the two types of centrifugal air compressors.

Single-stage centrifugal air compressors

Single-stage centrifugal air compressors are among the most used compressor units in the market. These compressor types have a single impeller that directs the air for compression. A single-stage centrifugal air compressor comes with a diffuser attached to the guide vanes. The compressor unit can offer up to a 3:1 compression ratio due to its impeller peripheral speed and blade geometry. Additionally, single-stage compressors have flow capacity ranging between 1000 cfm and 300,000 cfm. 

Single-stage centrifugal air compressors can also be integrally-geared single-stage compressors or overhung single-stage compressors. 

Multi-stage centrifugal air compressors

Multi-stage centrifugal air compressors are another type of centrifugal air compressors. These compressors are made to pass compressed air through multiple compression stages for different applications. Multi-stage centrifugal air compressors are used in applications where single-stage air compressors can’t keep up with the pressure requirement. 

Multi-stage centrifugal air compressors are designed with many impellers on the rotor. Every impeller diffuser is made to leave the discharge as the air enters the next impeller. Multi-stage compressors multi-stage air compressors can be sub-classified into other compressor types, including:

• Pipeline multi-stage compressors
• Integrally geared multi-stage compressors.
• Multi-stage centrifugal compressor with horizontally split casing
• Multi-stage centrifugal compressor with vertically split casing
• Multi-stage centrifugal compressor with bell casing

Advantages And Disadvantages of Centrifugal Air Compressors

Advantages of Centrifugal Air Compressors

• They are generally lightweight with simple designs that are easy to produce. 
• They are oil-free; thus, they produce clean compressed air. 
• They are suitable for applications that require a constant supply of compressed air. 
• They are designed with fewer rubbing parts. 
• They are relatively energy-efficient machines. 
• They do not require a special foundation. 
• They produce a high-pressure ratio per stage than axial flow air compressors. 
• They are more reliable and low cost. 

Disadvantages of centrifugal air compressors

• They require complex mounting since they work at a high speed. 
• They experience surging, choking, and stalling issues. 
• They are not suitable for applications that require high compression at limited pressure. 
• They come with a large frontal area than axial flow compressors. 

Applications of centrifugal air compressors

Centrifugal air compressors are used in a wide range of industries. Here are some examples of sectors that require centrifugal air compressors to work efficiently: 

• Food and beverage industry
• Gas turbines and superchargers
• Oil and gas industry 
• Pneumatic tools in the manufacturing industry
• Air conditioning and refrigeration

Frequently Asked Questions 

What Is the Price of a Centrifugal Air Compressor?

Industrial centrifugal air compressor prices vary significantly. The figures quoted here are estimates meant to give you a general idea of centrifugal air compressor costs. 

On average, you can buy centrifugal air compressors at the following price ranges:

• 5hp centrifugal air compressor for $1500 to $5000
• 25hp centrifugal air compressor for $5000 and $8000
• 100hp centrifugal air compressor for $20000 to $35000 
• 200hp centrifugal air compressor for over $70000

What Are the Main Parts of a Centrifugal Air Compressor?

A centrifugal air compressor is made of different parts. The good news is that this compressor type has fewer internal rubbing parts, making them more reliable, efficient, and low-maintenance. The main parts of a centrifugal air compressor include the impeller, diffuser and volute. Other centrifugal air compressor components include:

• Idler shaft
• Input shaft bearing
• Drive gear
• Seal housing
• Gearbox seal
• Diffuser shroud
• Discharge flange
• Compressor’s casing

What Is the Application of a Centrifugal Air Compressor?

Centrifugal air compressors are used in many industries for various applications. Some of the applications of centrifugal air compressors are in refineries, chemical plants, onshore and offshore oil and gas exploration, and food and beverage. 

What Are the Main Brands of Centrifugal Air Compressor?

There are many centrifugal air compressor manufacturers. Some of the best centrifugal air compressor brands include:

• Atlas Copco centrifugal air compressors
• Ingersoll Rand centrifugal air compressors
• Quincy centrifugal air compressors
• Sullair centrifugal air compressors
• Kaeser centrifugal air compressors

Conclusion

In summary, centrifugal air compressor basics are all about the structure, construction, and applications of a centrifugal air compressor. Beyond the maintenance and costs, you should evaluate what makes a centrifugal air compressor to understand its working principle and whether it is suitable for your applications or not. Additionally, you may want to compare centrifugal air compressors to other compressor types, such as axial flow compressors and screw air compressors.