Regenerative blowers are the ideal solution for moving large volumes of air at lower pressures or vacuums. Unlike positive displacement compressors and vacuum pumps, regenerative blowers "regenerate" air molecules through a non-positive displacement method to create vacuum or pressure. In the world of air handling equipment, regenerative blowers are probably the least understood of today's technologies, but when system parameters fall within the range of a regenerative blower, it can be the most cost effective method for producing pressure or vacuum.
Regenerative blowers are also called side channel blowers or ring compressors, terms that refer more to their physical construction. The more common name regenerative comes from their basic operating principle, as discussed below.
Regenerative blowers in plant installations are typically in a direct drive design, versus electric motor / gas engine belt drive configurations. (refer photo depicting these 2 designs). The impeller in the direct drive (sometimes called monobloc) construction is mounted directly on the electric motor shaft and rotates at the motor's nominal speed, typically 2900 or 3500 rpm. The impeller consists of numerous radial blades on the circumference of the impeller. The number, size and angle of these blades contribute to the pneumatic performance (flow vs. pressure / vacuum) characteristics of each blower. Some makes of blowers have somewhat "flat" curves (Y axis =pressure / vacuum, X axis = scfm), while other makes have quite steep performance curves. The impeller spins within a housing that consists of an inboard and outboard "channel" (hence the term side channel blower). As the impeller passes the inlet port, air is drawn in. As the impeller rotates, air is captured between each blade on the impeller and is pushed both outward and forward into the channels. The air then returns to the base of the blade. This process is repeated over and over as the impeller spins. It is this regeneration that gives the blower its pressure / vacuum capabilities. In essence, a regenerative blower operates like a staged reciprocal compressor and while each blade to blade regeneration "stage" results in only slight pressure increases, the sum total, from air entry to outlet can yield, in some makes continuous operating pressures up to 9 psig or vacuum to 14" hg with flows in the 200 to 250 scfm range at these points.
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