Working Principle of Dynamic Compression in Turbo Blowers

Single stage high-speed turbo blower

The single stage high-speed turbo blower follows the compression principle of the centrifugal compressor, or dynamic compressor with radial design. It works at constant pressure with performance depending on external ambient conditions delivering compressed air without pulsations. This is different from the positive displacement compressors working at constant flow, where the inlet air density does not affect performance and the compression is pulsating.

Air is drawn axially into the center of the impeller with radial blades and is pushed radially by means of centrifugal force. The rotation of the impeller accelerates the speed of air (kinetic energy), and forces it to pass through the downstream diffusers and volute. Here, the high kinetic energy is converted into potential energy (pressure) slowing down the speed of the air through expansion. The velocity energy is converted into pressure energy according to Bernoulli’s principle (pressure is inversely proportional to velocity squared).

The optimal operation of a turbo blower is achieved when the blower is performing within its specified range of air flow. Maximum efficiency for turbo blowers is a product of both pressure and air flow, and is limited by surge and choke.

Surge is the reversal of flow within the dynamic compression process. It takes place when the capacity being handled is reduced to a point where insufficient pressure is being generated to maintain flow. This means that as the flow travels through the compressor, the pressure has reached the maximum limit of the compressor impeller that it can push against. Since the compressor cannot overcome the pressure, the air flow slips backwards rather than being pushed into the system. This leads to vibrations that can potentially damage internal components. To prevent such occurrence, the bypass valve (Blow-Off valve) is open before reaching the surge point.

Choke occurs when the compressor is operating at low discharge pressure and very high flow rates. The compressor maps for a fixed RPM value, compressor output increases as the backpressure at compressor discharge drops. This leads to an increased gas velocity. The increase in gas velocity occurs until it reaches its maximum at sonic velocity. The choke point (or stonewall) is reached when the air velocity is close to sonic velocity MACH 1 in any of the compressor parts. The air velocity and flow rate cannot go beyond this value.

Turbo Blower for low static pressure operations

The Runtech Systems RunEco EP Turbo Blower is specifically designed for low static pressure operation, for example vacuum, often used in applications in the pulp and paper industry. It is a radial turbo design that provides a higher gas flow volume as is evident in its relatively larger size. It is also designed to be more robust allowing it to perform in harsh conditions where the air is not pure, and the working environment tends to be more corrosive. That’s why the impeller is made from Grade 5 titanium, and is directly coupled to the motor shaft. 

Furthermore, the seal between the high-pressure zone (inside the volute) and the low-pressure zone (suction cone) is achieved through a labyrinth end seal. The rotor design is subcritical to natural frequencies of the system enabling for a wide operating range. A special consideration has been paid to the bearing design to provide trouble-free operation even when the rotor is unbalanced during operation.

Turbo Blower for Wastewater Treatment

HOFFMAN’s REVOLUTIONPLUS Blower for municipal and wastewater treatment combines an advance blower management system with a significantly smaller physical footprint than traditional blowers to set a new standard for blower design, performance, and efficiency.

The REVOLUTIONPLUS uses innovation and advanced technology to deliver energy savings of up to 40%, increased reliability with low maintenance requirements, and are factory pre-wired and tested in an ergonomically designed sound enclosure for plug-and-play operation.

Hoffman produces a variety of turbo blowers with power inputs ranging from 10 to 700 horsepower, making them ideal for a wide range of applications. Our turbo blowers provide innovative technology for municipal and industrial wastewater treatment, brewing and distilling, and power generation.

Turbo Blower for Wastewater Treatment

At Robuschi, we have been providing products and services for the low pressure compressed air market for decades. We have supplied generations of customers worldwide with our innovative blower solutions. Our latest innovation comes in the form of a blower boosted by turbo technology. Now, you have access to a full spectrum of low pressure technologies, including lobe, screw and now turbo blowers.

The Robuschi Robox Turbo is equipped with a centrifugal high speed turbo blower. Designed to be compact and efficient, but also provide increased and more reliable performance due to its capability to overclock the turbo to provide more air pressure when needed.

The efficiency of turbo blowers can tackle energy concerns in wastewater treatment plants, and at the same time decrease their environmental and financial impacts (total cost of ownership).