Regenerative blowers are machines used to move air by way of a non-positive displacement method. A positive displacement device would trap a quantity of air and force it to move a given distance in a given direction. The method by which regenerative blowers move the air, however, allows some air passing over a blade of the impeller to slip past it. This air is moved forward by another blade.
The structure of a regenerative blower is relatively simple. It consists of an impeller with blades radiating out from it. This impeller is enclosed in a housing with empty space between the tips of the blade and the housing so they have no contact. Air flows into the blower through an inlet port and out through an exhaust port.
To operate the blower, a motor or engine drives the impeller such that the blades rotate inside the housing. The air blower draws air in through the inlet, and this air makes contact with a blade on the impeller as it enters. Contact with the moving blade accelerates the air, thereby moving it outward toward the housing. Pressurized air is discharged from the blower through an exhaust outlet, but not all of the air touched by a given blade exits right away.
A circular ring of space between the impeller blades and housing allows some air to slip past the first blade with which it makes contact. Regenerative blowers are sometimes referred to as ring compressors or ring blowers for this reason. This air falls to the base of the succeeding blade. Contact with this second blade then re-accelerates this air in the same way as the first.
Many applications make use of regenerative blowers, from heavy industry to chemical and environmental processes. They may be used in operations such as packaging, lifting, and conveying products in a factory; dust and smoke removal; sewage aeration; and soil vapor extraction. In general, regenerative blowers are best suited for applications involving high rates of airflow at low pressure or where a vacuum is required.
Regenerative blowers operate with high efficiency and are usually relatively compact in size for the large amount of air they move. They produce lower amounts of acoustical noise than many other types of blowers, and they generate little vibration as they operate with dynamically balanced impellers. With the only moving part in each unit being the impeller, regenerative blowers are highly reliable and experience little wear. Consequently, they require little maintenance or downtime.
Minimal clearance between the impeller and the housing necessitates that debris be kept out of a blower for failure-free operation. Filtering air before it enters the blower is a good way to keep the unit clean and the impeller moving freely. If the impeller and housing lock up, the unit may be damaged beyond repair.
Some regenerative blowers rely on airflow through them for cooling purposes. Excess pressurization of the unit may cause airflow to slow or stop thereby impeding the necessary cooling. If the impeller of a blower heats up at a different rate than the housing, it may expand in size faster than the housing. Such a mismatch can result in impeller movement being impeded by contact with the housing. This may also result in a catastrophic failure.