INTRODUCTION OF ROOTS BLOWERS

I. The introduction of Roots blowers

The Roots blower, also known as a Roots fan, air blower, vacuum pump, or silo aerator, depending on its function and purpose, is a type of machine with a unique and innovative design, which has been around for hundreds of years. The first design of this machine was patented in 1860 by two American designers, Philander Higley and Francis Marion Roots. Since 1944, Roots blower has been a brand of Dresser Industries, and the Dresser fan company still produces this type of fan today.

Nowadays, this type of machine has been researched and manufactured by many companies around the world, such as Robuschi Blower from Italy, Dresser Root from the US, some Japanese air blower manufacturers such as Anlet, Tsurumi, Shinmaywa, and some companies from Taiwan such as Longtech, Heywel, Greatech, Goldentech. In conclusion, machines originating from Europe or Japan are better, although they are more expensive (about 2-3 times higher) than air blowers with the same specifications originating from Taiwan. Therefore, depending on the economic financial resources and usage requirements, one should choose a suitable air blower.

II. Some typical applications of Roots blower

Currently, different types of air blowers, including Roots blowers, are widely used in many industrial manufacturing fields.

• Application in fly ash recovery and dimension removal in thermal power plants.
• Application in the treatment of industrial wastewater.
• Application in the mining and metallurgical industries.
• Application in cement factories.

III. Working principle of Roots blower

The principle of operation of the Roots blower can be explained by the diagram below.

Two interlocking rotors 1 and 3 rotate around a fixed axis in the direction of the arrow in the figure. When the two rotors rotate and combine with the casing, they form an inlet (suction), an outlet (discharge), a suction chamber (yellow part a), a compression chamber (pink part b), and a discharge chamber (red part c). When the rotors rotate at the working speed, the suction, compression, and discharge chambers are continuously formed and transport air from the suction inlet to the discharge outlet.

Basic working positions of Roots blower

To minimize losses and ensure the working efficiency of the air blower, the clearances between the rotor pair, and between the rotor and the casing must be small and suitable, which is usually standardized for each type of blower and manufacturer. These clearances must be maintained at all rotor positions. Typically, after a period of operation, these clearances may increase, causing the machine's operation to no longer meet the specified working parameters.