Regenerative blowers move air using non-positive displacement. They allow some air to pass over a blade and then forward using another blade.
This is different from machines that use positive displacement that work by trapping air and forcing it to move.
These devices are relatively simple and use only the blades and enclosed space to operate. Air flows into the blower through a port and out through a different port.
Regenerative blowers operate using a motor or engine that causes the blades to rotate.
How are Regenerative Blowers Used?
There are several different reasons why you might need a regenerative blower. Industries that work with chemicals or environmental processes often use regenerative blowers. They are also used in lifting, packaging, and conveying products. A regenerative blower can be used to remove dust or smoke from the air, extract soil vapor, or perform sewage aeration. They are well-suited for applications that require high rates of air flow at a low pressure, or when a vacuum is required in a process.
What are the Beneficial Features of Regenerative Blowers?
The benefits of regenerative blowers include their ability to operate at a high efficiency. They are usually small in size considering the amount of air they are able to move. They are also quiet and create very little vibration.
Regenerative blowers are also easy to maintain and operate in a simple manner that results in fewer breakdowns. There is only one moving part inside the blower (the impeller), so there is little wear and tear overall. These reliable machines require little maintenance and are easy to use.
Becker Pumps offers two different types of blowers: 1-stage and 2-stage. Both feature many of the same advantages, and if necessary, can be converted into the different stage blower. (One can be converted to two and two to one, if needed.)
We also guarantee our blowers will have all the features you expect, including quiet operation, dependability, and low maintenance.
Improving Efficiency for Regenerative Blowers
The side channel design of regenerative blowers has been a staple for over fifty years in the industry. The continuous and pulsation-free volumetric flow of these blowers is a unique characteristic, especially in comparison to reciprocating machinery. Furthermore, these side channel blowers, when likened to axial and radial machines, generate a substantially larger pressure ratio.
The rotor disc accelerates all air taken into the blowers, after the air passed around the outer area of the side channel, it is then moved around the perimeter of the side channel and then into another chamber of the rotor disc. This process is repeated over and over to build up pressure during the circulation of the rotor disc. Around half of a rotation is when a large portion of the compressed air leaves the device. The rotor disc in the regenerative blowers then send the remaining amount of air to the inlet of the device where it will be mixed with fresh air.
Although the production stage for this model series of regenerative blowers was already reached, there are still important optimizations possible for enhancing their efficiency. For instance, drive optimization can be improved by increasing the flow area, thus raising the efficiency of the blowers.
Drive in Regenerative Blowers
Regenerative blowers now must meet new efficiency classes introduced by the legislature.
Motors with 0.75 kW or higher now need to have and efficiency rating of at least 77.4% (2-pole motor). Higher power rated motors must now reach an efficiency rating of at least 95.4%. This high efficiency class IE2 is the initial step in significantly reducing a motor’s energy consumption. After January 1, 2017 these values were tightened. During those first two phases, the minimum efficiencies were increased. The first phase moved the minimum efficiency up to 95.8%, based on a 2-pole motor. This will also be a requirement for motors with shaft power ratings of 7.5 kW or higher. On January 1st 2017, a later phase was introduced in which motors with a power of 0.75 kW and higher must meet values of the IE3 efficiency class, or premium efficiency. An alternative option to equip motors with an electronic speed control in conjunction with the IE2 motors is also available.
Increasing the quality of materials used in regenerative blowers and making geometric modifications to the motor size and package length drastically improves the motors. This can mean higher prices but these expenses are typically reimbursed by lower operating costs. Due to this higher expense, it can still be difficult to remain successful in the market.
Also, motor efficiency is high, relative to the efficiency of the regenerative blowers. This makes it extremely important for the hydraulic and volumetric compressor efficiency to be enhanced so that overall power consumption is reduced. Any increased motor costs will eventually be compensated by the optimization of the regenerative blowers. In these regenerative blowers, the drive represents a significant part of the total costs. This increases the difficulty of maintaining low costs while raising efficiency. Regenerative blowers can be applied to a wide range of operating applications; therefore, it is a requirement to reach the highest possible rate of efficiency across all uses due to the device load and efficiency changing at each operating point.
Double-sided rotor discs are typical in the designs of regenerative blowers. They can be used for two-flow and two-stage configurations. The pressure ratio with two-stage operations increases at the expense of volume flow. The geometry of the rotor disc needs to guarantee that the two halves of the disc are sealed off from each other. However, for double-flow operations, the volume flow can be increased by lowering the possible pressure ratio, allowing the device to be adjusted to any customer’s operating point, further improving efficiency.
3.2 Flow Route
The geometric specifications of the main dimensions are an important aspect of achieving an optimal design for regenerative blowers. The parameters of the geometry are decided through a proper combination of the rotor disc’s outside and inside diameter; length and design of the interrupter; number of blades, blade angle, etc. Once these values are defined, flow channels, including the outlet and inlet, are designed so pressure can build-up in a controlled manner. 3D CAD software confirms that the channels are optimized, and using a computational fluid dynamics (CFD) simulation, the effectiveness of the geometries is tested. During this simulation, regenerative blowers represent a complex, transient computational model.
Ensuring the new optimizations produce the proper result before the first models are created is a significant advantage of this approach because it renders numerous tests unnecessary.
Next, the resulting parts need to be fully realized using casting production methods. However, some designs either cannot be used or are associated with increased costs, depending on the casting process. It is necessary that compromises be made when flow optimization and costs of the regenerative blowers are being considered.
Lastly, another important part of creating optimal designs for regenerative blowers are the size of the gaps between the moving and static parts. Different manufacturing tolerances can be reached, depending on the applied casting processes. Die casting is commonly more accurate than sand casting. In addition to the gap sizes, tolerances for the subsequent device are also important. The larger the tolerances and gaps between parts, the greater the loss. This has an immense effect on the efficiency of regenerative blowers; therefore, keeping the tolerances as small as possible and maintaining reasonable production costs and reliable production methods is imperative.
Adjusting Speed to Change the Operation Point of Regenerative Blowers
In the industry of contact-free turbomachinery, regenerative blowers are best suited for operations with varying speeds. Thus, increasing power density can be achieved by increasing the speed, typically up to 100-120 Hz. Furthermore, it is possible to set the speed and the volumetric flow to each customer’s specific needs.
The regenerative blowers’ characteristics make them applicable in many operating conditions. This allows the blowers the capability of working at a reasonable efficiency without losses from blow-off valves and throttles. In addition, a frequency converter can be integrated into the drive to increase the ease of use.
Regenerative Blowers and Design
The design of newer regenerative blowers plays a pivotal role, as opposed to devices previously built. It is important that efficiency-optimized
designs do not have a negative impact on the flow route. Thus, there are some limitations with respect to the design of the blower’s outer shape. This requires a good compromise between aesthetic and functionality.
When these aspects are considered together, a new optimized device that consumes significantly less power at a comparable operating point is created. Optimizing and improving the individual components of regenerative blowers makes it possible to make major enhancements, even for devices that have existed for some time.
This process holds many positive side effects, including the reduction of both size and weight, which improves the ease of integration. This has a positive effective on the energy performance by conserving resources. The newly optimized flow route also reduces the noise production of the device. Much of the noise caused is created by the flow noise, which has been improved upon drastically.
To learn more or to discuss your regenerative blower needs, contact Becker Pumps.