To understand how blowers work, it helps to start with the idea that a blower is a type of fan designed to produce higher pressure and velocity than ordinary ventilation fans. Most industrial blowers use either centrifugal or positive-displacement principles to increase the energy of the air so that it can be pushed through equipment, pipes or burners with relatively high resistance.
The most common industrial design is the centrifugal blower. Air enters the blower through an inlet at or near the centre of a rotating impeller. As the impeller spins, its blades grab the air and accelerate it outward by centrifugal force into a surrounding scroll-shaped casing. As the air moves from the centre to the outer edge, its velocity increases. The casing then converts part of this velocity into static pressure by gradually expanding the flow area and directing the air toward the outlet. The result is a stream of air at higher pressure that can travel through narrow passages, nozzles or small ducts.
In many catalogues, a centrifugal blower looks similar to a centrifugal fan, but it is often designed with tighter clearances, specific blade shapes and higher speeds to achieve a higher pressure ratio. The impeller may have forward-curved, backward-curved or radial blades, depending on the required pressure, efficiency and dust-handling capability. The blower is driven by an electric motor through a direct coupling or belt drive, and the motor power is sized to provide the energy needed for the required flow and pressure.
Another class of blowers uses positive-displacement principles, such as Roots blowers or screw blowers. In these units, two or more rotors trap fixed volumes of air and carry them from the inlet to the outlet, compressing the air as it moves. These blowers produce relatively constant flow regardless of pressure changes and can reach higher pressures than most single-stage centrifugal blowers. They are commonly used for aeration, pneumatic conveying and processes requiring stable airflow.
Blowers are controlled in several ways. Flow and pressure can be adjusted by changing speed with a variable frequency drive, throttling with dampers and valves, or in some positive-displacement machines by bypassing part of the flow. Instrumentation such as pressure gauges, flow meters and temperature sensors helps operators verify that the blower is working within its design range and that downstream processes are receiving the correct air supply.
In summary, blowers work by spinning an impeller or displacement rotor to add energy to air, increasing its pressure and velocity so that it can overcome higher resistance in pipes, burners, process equipment or conveying lines than a standard ventilation fan could handle.
