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Air Blowers

Air is important for all of us. We need it to live. But did you know blowers are also crucial in sustaining our lives?

We need blowers to decontaminate manufacturing processes for meat, poultry, dairy products, fruits, vegetables, and beverages. We need them in wastewater treatment facilities to blow air into tanks to accelerate the process of reducing the harm the water can cause. In high-speed print manufacturing systems, we need air blowers to rapidly dry printed images. In coal mines, blowers are necessary for providing ventilation to enabler easier and healthier breathing for coal miners.

Blowers are used for these and many other applications around the world, in industries ranging from metal processing to cement production to petrochemicals and more. These devices create processes that are more energy efficient, productive, safe, economical, and reliable.

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Difference between air blowers and air compressors?

A typical blower can look quite similar to an air compressor. However, these devices are fundamentally different.

Think of an air blower as a fan that blasts large quantities of air continuously from one location to another, at faster speeds than a typical house fan. Used for heating, cooling, ventilating, and transporting, blowers produce lots of air in order to create additional airflow, but at a relatively low pressure compared with an air compressor.

By contrast, an air compressor squeezes more air into a smaller space at higher pressure intensity than an air blower. It actually makes the air denser. The purpose is to provide intense pressure to enable tools and applications to work with powerful force.

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How do blowers work?

So how does a blower work? At the start, air gets sucked into the suction side of the device. The rotors and impellers rotate. The air then gets pressurized and released.

Depending on how they move the air, blowers can be classified as either positive displacement or centrifugal.

  • Positive Displacement: These types of blowers, housing two rotors, trap a certain volume of air; they then discharge or force it out against the system pressure. Once in operation, a blower rotates at the same speed, but in opposite directions, to draw air into the blower. As the rotors revolve, air gets pulled into the inlet side of the blower and becomes confined to tight areas between the rotors and the blower casing. This pocket of air moves around the rotors and blower casing to the outlet side. When the rotors open to the outlet side, the discharge line equalizes the air pressure. Within the blower, the volume of air does not change. Rather, it is displaced from one end of the machine to the other.
  • Centrifugal: Air enters the center of a spinning impeller and divides between the impeller's blades. As the impeller turns, it accelerates the air outwards using centrifugal force. In the surrounding blower housing, this high-velocity air diffuses and slow to create pressure. Because centrifugal machines operate with pressure and flow rate as dependent variables, centrifugal blowers operate best as base load machines or in applications with constant pressure.
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Types of blowers?

Rotary Lobe Blowers (aka Roots Blower): Rotary lobe blowers consist of two rotors spinning in opposite directions. The blower sucks in air, and the lobes spin the air around before pushing the air out. They produce a high volume of air but at low pressure. Although rotary lobe blowers require minimal maintenance, they let some air escape. As such, this is not the most energy-efficient option, especially when compared to screw blowers. Since they were invented in the 1800s, rotary lobe blower technology hasn't changed too much. The main advancements have been focused on noise reduction.

Rotary Screw Blowers: The rotary screw blower combines male and female rotors that rotate and decrease the available volume between them. This causes the air to compress. At the start of the compression cycle, the inlet air fills the flute space and becomes trapped. The air is then continually compressed as the male and female rotors rotate with each revolution until the air pushes through the discharged outlet. Compared with traditional lobe blowers, the internal compression of rotary screw blowers reduces energy consumption by 30 percent. By eliminating pulses caused by lobe technology, screw blower noise levels are typically three-to-five times quieter than conventional tri-lobe blowers.

Centrifugal Blowers: When an air stream passes through this blower’s rotating impellers, the speed and volume increase. Centrifugal blowers actually change the airflow’s direction. The air or gas enters the fan wheel, turns 90 degrees, and accelerates before exiting the blower.

Multistage Centrifugal Blower: Used for creating pressure, circulating air, and creating suction, this blower can handle high pressure and high flow rates. It is ideal for creating high pressure from small volumes of air. As such, the devices are well suited for all operations where a variable flow at constant pressure is a requirement. Performance characteristics of these blowers generate a variable flow and power at a constant speed. To generate more flow, the impeller diameters need to be increased; more impellers are required to create more pressure.

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What Industries & Applications Are Blowers Used In?

Food and Beverage: includes meat processing, poultry, dairy product manufacturing.

Wastewater Treatment: the wastewater is introduced to millions of bacteria in the aeration tank. The bacteria feed on the organic waste and break down the wastewater into harmless byproducts of carbon dioxide, nitrogen and water. Because the bacteria need oxygen to survive, large quantities of compressed air are blown into the aeration tanks to speed up the activated sludge process.

Pneumatic Conveying: used to move any dry bulk material, including powders, granular forms, chips and pellets

Mining: provides ventilation into coal mines; removes methane gas from underground coal mine basins in a process called methane gas extraction

Cement Manufacturing: blowers aerate the air cement silos, ensure that the raw material remains in motion, cool the mixture after leaving the kiln, and feeds oxygen to the fire

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