Active magnetic bearings (AMBs) are a type of bearing that uses magnetic forces to provide radial and axial support for rotating components. These bearings are used in turbo blowers to provide frictionless, low-vibration operation, as well as to improve efficiency and reliability. AMBs use a set of electromagnetic actuators, position sensors and an electronic controller to create a magnetic field that supports the rotor and eliminates mechanical friction. The AMB system components work together to continuously adjust the magnetic field in milliseconds to ensure the rotor is properly suspended, even when the system is running at high speeds and high loads. This allows the turbo blower to run more efficiently and reliably, improving overall performance.
Turbo blowers are widely used in industry. They are needed for blowing air or other gas for the process. Alternatively, the blower can be used to create a vacuum. The fundamental principle is to use a motor and impeller. The motor rotates the impeller, and the impeller moves the air or other gas. The pressure of the gas increases slightly, but the pressure increase is moderate and lower than in the compressor. There is no clear consensus with the line between the turbo blower and compressor in terms of gas pressure and volume flow. However, the blower is more for transferring large amounts of gas whereas the turbo compressor is primarily for increasing the gas pressure. Turbo blowers can be used for example in the following processes:
- Aeration
- Drying
- Pneumatic conveying
Figure 1. Example of a turbo blower
Turbo blower applications
The industries and applications that use the above-mentioned processes are:
- Wastewater treatment
– Aeration for oxidizing the biological purification process
- Chemical
– Pneumatic conveying of powders and raw material with pressurized, dry and oil-free air
- Pharmaceutical
– Cleaning and drying of machines, production rooms, packages, and bottles with clean air
- Pulp and paper
– Vacuum for dewatering pulp and paper
- Food and beverage
– Pneumatic conveying of ingredients, drying and sorting of equipment and products
- Aerospace
– Clean air for manufacturing aerospace devices, vacuum waste systems
- Automotive
– Clean air for painting, vacuum grip for moving components, windshields, body sheets
High-speed impeller
The word turbo refers intuitively to high-speed spinning. In general, that connects easily to automotive turbochargers, which serves as a good reference for turbo technology. High-speed spinning refers especially to the spinning of the impeller wheel. High-speed spinning can be achieved with a low or moderate-speed conventional electric motor and massive gearbox. Alternatively, direct-drive technology can be used, where the impeller wheel is directly connected to the high-speed electric motor. The difference between these two alternatives is explained in the video by The Switch, a Finnish electric motor manufacturer.
Direct drive turbo blowers
Direct-drive turbo blowers are the best solution for applications where the footprint is limited, or the operational performance requirements are the highest. Directly driven turbo blowers operate at high speeds and also in harsh environments.
If the turbo blowers are supposed to have a minimum need for maintenance, active magnetic bearings come into the picture. To build frictionless, maintenance-free turbo blowers, turbo blower OEMs need high-quality active magnetic bearings.
Active magnetic bearings levitate the rotational part of the electric motor using electromagnetic forces. By levitating the rotor there is no contact and therefore no wear between the rotating and stationary parts. This increases energy efficiency and reduces maintenance costs. Operation is totally oil-free and very robust against process disturbances or wearing or dirty impeller.
Lower operating expenses with magnetic bearings
Wastewater and water treatment plants are good examples of applications where there is a lot of use for turbo blowers. These turbo blowers represent up to 80% of the annual operating expenses. By introducing frictionless active magnetic bearings, operating expenses can be cut by 30%. Therefore, active magnetic bearings are often used in turbo blowers for wastewater and water treatment.
For a medium size water treatment plan, savings can be significant.
Request for more information
We have designed magnetic bearings for several types of turbo blowers for machine powers ranging from 200 kW up to 1 MW. Our technology is feasible also beyond these limits. Don’t hesitate to contact us and talk to our active magnetic bearing experts.
Author: Dr. Janne Heikkinen
Learn more about active magnetic bearings for other applications:
Active magnetic bearings for turbo compressors
Active magnetic bearings for high-speed spindles
Why magnetic bearings for high-speed applications?
Applications of active magnetic bearings