Air blowers are an important tool in modern industrial manufacturing. Along with air compressors, they are one of the basic pumps that provide air power and reaction media. Air blowers are specially designed to produce large, continuous low-pressure air flows.

From metallurgy to pneumatic conveying, from aeration to ventilation, from pipeline testing to HVAC systems, air blowers occupy an important role in a variety of applications. Air blowers come in many different models, types, sizes, air delivery and pressures. This guide introduces the types of air blowers, working principles, difference with air compressors, applications, and how to choose the best air blower for your application.

What is air blower?

Evolution of air blowers

Air blowers first appeared in blacksmithing works, metallurgy had already appeared in China 5,000 to 6,000 years ago. After entering the Iron Age in the 5th century BC, ironware became an important factor in promoting historical progress and once became a symbol of the level of productivity development.

Iron smelting is a combination of multiple technologies, and air blowing technology is an indispensable part of it. Air blowing is to blow certain amount of air into the furnace with a certain pressure to make sure complete combustion of the fuel, thereby obtaining a higher furnace temperature and improving smelting efficiency.

Metallurgical air blowing technology has experienced the development from intermittent air blowing to continuous air blowing, and the air blowing equipment has developed from leather bellows to wooden fans and piston-type wooden bellows.

The earliest instruments used for forced air blowing were fans and blowpipes. The murals in the tomb of Rekhmire (about 1450 BC) in the 18th Dynasty of Egypt have painted images of jar-shaped foot-operated blowers.

With the modern industrial revolutions and the development of science and technology, various large-scale blower machines have appeared today, such as the early Roots blower, and the later screw blower and centrifugal blower.

The development of air blowing equipment is not only an important part of the progress of iron smelting technology, but also affects more industries as the progress of mechanical technology.

In addition, with the development of technology, new air blowers such as magnetic suspension air blowers and air suspension blowers have emerged. These new air blowers use technologies such as magnetic suspension bearings and high-efficiency impellers.

They have the characteristics of no lubrication, low maintenance cost, and high operating efficiency. They are an important direction for the development of air blowers in the future.

Types of air blowers

An air blower is a machine that can develop and pressurize a large amount of airflow. It is mainly used to provide fresh air, gas or dust transportation, ventilation, and pressurization in various industrial applications.

According to working principles and mechanical structure, air blowers can be classified into roots blowers, screw blowers, centrifugal blowers. Some portable air blowers are also used as leaf blowers and vacuum cleaners.

(Roots blower)

Roots blower: Roots blower is a kind of positive displacement blower(PD blower), which adopts two or three lobe rotors to rotate in opposite direction in the cylinder to blow air, also known as lobe blower. Through the continuous relative rotation of the two rotors, air is sucked from the outside into the pockets between the rotors and the casing, and then discharged from the exhaust port.

(Screw blower)

Screw blower: Screw blowers are usually composed of two screw rotors rotating in opposite directions. The rotation of the screws compresses and transports the gas, achieving forced air supply. This type of structure is stable and reliable, and its efficiency is better than that of air compressors in low-pressure environments.

Therefore, it is widely used in various fields, such as waste gas treatment, water treatment, petrochemical industry, compressing natural gas, etc.

(Centrifugal blower)

Centrifugal blower: Centrifugal blowers(also known as centrifugal fans) use a spinning impeller to create a vacuum that draws outside air into the blower, spinning impeller apply centrifugal force to the airflow and increases its velocity and pressure.

A centrifugal blower that has only one impeller is a single-stage centrifugal blower, a centrifugal blower with two or more impellers is called a multi-stage centrifugal blower. Magnetic levitation blower(maglev blower) and air levitation blower are new technologies of centrifugal blowers.

Targeted air guidance is the difference between air blowers and ordinary fans. This also makes air blowers widely used in ventilation, coal, electricity, metallurgy, water treatment, pneumatic conveying and other industrial fields. Each type of air blowers has its specific technical characteristics and applications.

For example, Roots blowers have a wide range of choices in terms of pressure and flow parameters; screw blowers have a simple structure, good stability, and are relatively simple and convenient in terms of displacement and output pressure control; centrifugal blowers have the advantages of high efficiency, low noise, large and smooth airflow.

How does air blower work?

The rotors of air blowers

(Three-lobed rotors of Roots blower)

Roots blower: There are generally two lobe rotors in a Roots blower. The simple form of a lobe rotor is a cycloidal rotor, which consists of the tangential parts of alternating hypocycloidal and epicycloidal curves. There are two forms of lobe rotor, two-lobed rotor and three-lobed rotor. The profile of two-lobed rotor has smaller generating circles whose diameters are one-quarter of the larger.

(Screw rotors of screw blower)

Screw blower: Two screw rotors with opposite threads are mounted on parallel shafts. The two screws mesh with each other, one screw rotates clockwise and the other screw rotates counterclockwise. The spiral grooves between the two screws form a series of pockets. When air enters, the pockets filled with air will move toward the exhaust port as the screw rotors rotate (the two screws rotate but do not move, only the pockets appear and move periodically).

(Centrifugal fan of centrifugal blower)

Centrifugal blower: There are involute blades on impeller, which have different designs and sizes depending on the type of application and the desired effect. Forward curved blades can produce higher air velocity at low rotation speeds; backward curved blades rotate faster, with the flat part of the blade away from the direction of rotation, which can produce higher air pressure; radial blades are not curved and are often seen in small airflow applications.

Air blower working principles

(Roots blower working principle)

Roots blower: The Roots blower consists of two counter-rotating lobe rotors. The blower draws in air and drives it to flow through the gaps on both sides of lobe rotors to the discharge port, thereby complete accelerating and conveying the airflows.

The lobe rotors are driven by synchronous gears to rotate relative to each other at the same speed, which means that when the lobes on the rotors rotate to the meshing position, it can prevent air from flowing back but there is no relative friction happen in the contact point, which avoids the need for lubricating oil and enables the Roots blower to perform work with strict pollution control.

The air delivery of the Roots blower is positively correlated with the speed of the lobe rotors, but the pressure that can be generated is low.

(Screw blower working principle)

Screw blower: As rotary blower it works just like the rotary compressors, the screw blower relies on rotation of two screw rotors and several pockets formed by the two screw rotors. As the screw rotors rotate, the pockets volume changes continuously and periodically from large to small.

When the volume is the smallest, the pressurized air is discharged. The working process of the screw blower has the characteristics of internal compression and forced air supply. Within the load range, the exhaust pressure can be adaptively adjusted according to the back pressure.

The change in pressure has little effect on the air flow, and the air volume can also be adjusted by the rotation speed.

(Centrifugal blower working principle)

Centrifugal blower: Centrifugal blowers are also called turbine blowers. Their working principle is almost the same as centrifugal compressors which is that the motor rotates to drive the impeller to rotate. The air is driven by the rotating impeller to rotate together, and obtains centrifugal force and acceleration and is thrown out along the gradually opening gap between the impeller blades.

After the air hits the casing, the flow direction changes, the flow rate decreases and the pressure increases, and the kinetic energy is converted into static pressure energy.

Finally, the pressurized air is discharged from the exhaust port. When the impeller rotates, a certain negative pressure will be formed at its center, so that the outside air is replenished under the action of atmospheric pressure, so as to achieve the purpose of continuous blowing.

The magnetic levitation blower(maglev blower) is a turbo blower that adopts magnetic levitation bearings. Its main structure is that the impeller is directly mounted on the extended end of the motor shaft, and the rotor is vertically suspended on the active magnetic bearing controller.

It does not require a speed increaser or coupling. It is a single-stage high-speed centrifugal blower that is directly driven by a high-speed motor and speed-regulated by a frequency converter. Its core is magnetic levitation bearings and permanent magnet motor technology.

The air levitation blower is a centrifugal blower of a new concept. It draws on the turbine engines of aviation and spacecraft, applies advanced air suspension technology, and adopts two high-end core technologies, “high-speed direct-connected motor” and “air suspension bearing”.

It improves the speed gear coupling, cooling system and oil lubrication system of traditional single-stage high-speed turbo blowers, greatly improving the product’s technical performance and operational reliability.

What is air blower used for?

In food industries, we need air blowers to help meat processing, large-scale poultry farming, dairy fermentation, fruit, vegetable and beverage production, etc.

In water treatment industries, we need air blowers to blow air into water tanks in wastewater treatment facilities to accelerate the reproduction of specific microbial communities and decompose harmful substances in wastewater, which is what we often call aeration.

In high-speed printing manufacturing systems, we need industrial blowers to quickly dry printed images.

In commercial places, air blowers are widely used in ventilation, dust removal and cooling.

In industrial plants, air blowers can inhale and transport air to various work areas to maintain air circulation and provide sufficient oxygen to help people breathe and blast furnace combustion, etc.

In mining, air blowers can deliver fresh air to mines to ensure the safety of underground workers; remove methane gas from underground basins in coal mines and increase concentration through flotation and leaching.

In the field of environmental protection, air blowers can be used for exhaust gas treatment, transporting exhaust gas to designated locations for treatment.

In pneumatic conveying, air blowers can be used to convey any dry, bulk material, including powders, granules, chips and pellets. For example: cement, lime, detergent, etc.

In the metallurgical industry, air blowers are used to supply oxygen to furnaces, keep raw materials flowing, cool the mixture after it leaves the kiln, and can also be used to clean SCR catalysts.

Air blowers are used in all aspects of our lives, from blowing fallen leaves to indoor ventilation, from snow blowers to industrial blowers, from exhaust emissions to sewage treatment, from pneumatic conveying to petrochemicals and many other applications, all of which are inseparable from air blowers. These devices make the process more energy-saving, efficient, safe, economical and reliable.

What is the difference between air blower and air compressor?

Air blowers look very similar to air compressors. However, these machines are fundamentally different. An air blower is more like a large fan that can blow a large amount of air from one location to another continuously, except that the air moves faster and at a higher pressure than an ordinary household fan, but their pressure is relatively low compared to air compressors. Air blowers are used for heating and cooling systems, HVAC systems, and pneumatic conveying applications and others.

In contrast, air compressors squeeze more air into a smaller space to develop a higher pressure intensity of air than air blowers. It actually makes the air denser, aims to provide strong pressure to enable air tools and related applications to have strong power to work. Different types of compressors have various parameters and suitable applications.

Both air equipment develop pressurized airflow during operation. However, they are basically different at compression ratios. Air compressors compress air with a higher compression ratio. Air blowers main purpose is to convey air, or convey materials by airflow, they only require a little air pressure and velocity, so the compression ratio is naturally lower. Thereby the two are different in performance, cost, and energy consumption, etc.

Air blower applications

Air blowers are used in various industries such as metallurgy, chemical plants, organic fertilizer,  food, decorative building materials, crude oil, mining, textiles, gas stations, pneumatic conveying, wastewater treatment, petrochemical industry, etc. Each type of air blowers has its unique advantages based on its design, working principle and desired applications.

For example, rotary lobe blowers excel in low-pressure continuous airflow due to its working principle, Roots blowers are widely used in applications that require constant airflow and low/medium air pressure, such as gas transportation in sewage treatment and fine chemical production.

Moreover, because of the oil-free airflow it developed, Roots blowers are very suitable for conveying clean air, coal gas, sulfur dioxide and other inert gases. They are the preferred products for special gas industries (coal gas, natural gas, biogas, carbon dioxide, sulfur dioxide, etc.). Roots blowers are also commonly used blowers in small and medium-sized sulfuric acid plants.

On the other hand, the application range of screw blowers is more broad. Due to its mechanical structure and working principle, the rotary screw blower has higher compression efficiency, can provide higher air pressure, with quiet, stable operation as well as higher energy efficiency, and is suitable for various industrial environments and different applications such as processing equipment and pneumatic tools in industrial production, air purging, gas transportation and drying, air conditioning systems, gas turbines, boiler ventilation, etc. It is also often used for pressurization of industrial emission systems, such as control and treatment of industrial waste gas emissions.

(KSB Series Low Pressure Oil Free Screw Air Blower)

Centrifugal blowers can handle larger airflow, operation is energy-saving and oil-free, can provide clean air supply for special industries such as medicine, electronics, food, aviation, etc. Multi-stage centrifugal blowers can easily process small amounts of air into high pressure, so they are widely used in aeration, petrochemicals, metal smelting, thermal power generation, sewage treatment, waste heat recovery, desulfurization and denitrification, etc.

Centrifugal blowers also include air suspension blowers and magnetic suspension blowers. These new technologies further improve the efficiency and reliability of centrifugal blowers, and reduce the maintenance costs.

How to choose the right air blower?

Different types of blowers have different advantages and disadvantages. For example, the airflow delivered by Roots blowers is proportional to the rotation speed of lobe rotors, with a simple structure and stable performance, the flow rate changes little when adjusted within the allowable pressure range, and the pressure selection range is very wide.

However, Roots blowers have low insulation efficiency, high noise, high energy consumption, and pulsating air flow. The pulsation of the air flow may cause cavitation and/or damage the components downstream of the blower.

The screw blower can easily compress and transport air by driving the screw rotors to rotate at high speed through synchronous gears. It has higher compression efficiency and exhaust pressure, and the displacement and output pressure control are relatively simple and convenient. At the same time, screw blowers usually have good sealing performance, can greatly reduce gas leakage, and the system is highly stable.

However, the screw is easy to wear and needs lubrication with lubricants such as oil, the air and product may be contaminated, and may need to remove oil sludge and carbon deposits.

Centrifugal blowers have the characteristics of high energy efficiency, low energy consumption, large air delivery, low noise, smooth operation, no pulse, wide stable area, clean and oil-free gas, few wearing parts, easy installation, operation and maintenance.

The optimized impeller reduces the axial force to the lowest level, and the static and dynamic balance correction makes the air flow smooth. However, centrifugal blowers rely on centrifugal force to compress the gas, which is more prone to surge risk.

In general, Roots blowers, screw blowers and centrifugal blowers each have their own scope of application and characteristics. For applications requiring low/medium-pressure airflow, Roots blowers are very suitable; for applications requiring high-pressure airflow, screw blowers are a better choice; and for applications requiring high flow, centrifugal blowers are a more suitable choice. Different types of blowers have different advantages and disadvantages.

Considering all these factors will help determine the blower that best meets your industrial requirements and ensure long-term efficient performance and cost-effectiveness.

Explore Kotech’s air blowers

The above is a brief introduction to what is air blower and how does it work, as well as its advantages and applications. If you want to know more about air blowers, you can click the consultation button by the right side. Kotech is a leading air blower manufacturer and is the first choice for all your compressed air solution needs.

Our experts team is experienced and professional, and can help you solve any problem you may have on air compressors. From selection to installation to maintenance, we can provide a complete guide including optimal advice and solutions for your project.

KSB series low pressure oil free screw air blowers are created with optimized sound insulation design, making its noise as low as 73 ~ 85dB (A). Oil free double-screw air end and optimized profile design for higher efficiency and lower energy consumption.

KSB series air blowers adopt international 5-level precision synchronous gear and combine labyrinth seal and carbon ring seal to achieve oil and air isolation, make sure the compressed air is 100% oil-free.