Centrifugal compressors are typically mounted with two or three main bearings. The main bearings support the main drive shaft, which cycle pumps gas compressor impellers that are arranged in series. The bearing arrangement provides a balanced system, which helps minimise vibration, increase efficiency and reduce noise.
The two most commonly used bearing types are radial or sleeve bearings and thrust bearings. Radial or sleeve bearings are the most common type and support the radial thrust of the compressor, whereas the thrust bearings typically support the axial thrust.
Radial or sleeve bearings are usually split into two parts – an inner race and an outer race. The inner race usually fits onto the drive shaft to support the weight of the impellers and the outer race supports the bearing on the compressor casing. High quality radial bearings should be chosen to reduce noise and vibration, as well as increasing bearing longevity.
In contrast, thrust bearings are usually much larger and the most common types are either ‘ball’ or ‘roller’ bearings. These are specifically designed to support the primarily vertical thrust produced by the compressor. They allow some axial movement but must be placed as close as possible to the compressor impeller to reduce vibration.
The main bearing supports installed in a centrifugal compressor are essential for the safe and reliable operation of the system, and choosing the right type based on your application is critical for optimising compressor performance and reliability.
In order to ensure that your centrifugal compressor is fitted with the most suitable type of bearing support for your application, it is important to consider factors such as the speed and temperature of the compressor, the load that needs to be supported, and the size of the bearings required.
When selecting the bearings for your centrifugal compressor, it is important to ensure that they are properly sized to handle the load they are intended to take and that they are designed to handle the varying temperatures and speeds of your compressor. If the bearings are not properly sized, they may cause excessive vibration, noise and premature fatigue.
In addition to size and type, it is also important to determine if the bearings need to be lubricated and at what frequency they need to be lubricated. Depending on the type of bearing and application, it may be necessary to lubricate the bearings regularly or to use oil bath-style lubrication. The frequency at which the bearings should be lubricated will depend largely on the amount of heat generated during operation.
Centrifugal compressors may also require specialized lubricants, depending on the application, in order to enhance reliability and reduce wear and tear. The type of lubricant should also be chosen based on thermal ratings, compatibility with materials and bearing selection. Specialized lubricants are also often required to meet specific safety regulations.
To ensure the long-term performance of your centrifugal compressor, it is important to select the most suitable main bearings to handle the loads present, understanding the conditions of your application and how often the bearings must be lubricated. Choosing good quality bearings, lubricants and ensuring regular maintenance are all important steps in ensuring that your compressor runs reliably and efficiently.
