What is BLOWER and types of blowers?

What is BLOWER?

Blower is a machine which is used to move air at moderate pressure. OR simply, blowers are used for blowing air/gas in a specific or given area.A blower can develop a maximum pressure of about 202 kiloPascals, which is equal to 2 atmospheres.

 blower

Working principle:

Blowers increase the pressure of the absorbed gas by the centrifugal movement of the impeller. when the impeller is rotating, the channels in the impeller push the air forward by centrifugal movement and a helical movement occurs. Then the gas is continuously compressed along the channel and the pressure increases linearly. Then the pressurized air is transferred from outlet duct of the blower.

*In a blower the inlet pressure is low and the outlet pressure is high. Because the kinetic energy of the blades increases the pressure of the air at the outlet.

Types of blowers:

*Blowers are classified into two types they are

  (1) positive displacement blowers

  (2) centrifugal blowers

*Blowers also use blades in  various designs like fans. Such as backward curved, forward curved and radial, they are mainly operated by a electric motor.

(1) Positive displacement blowers:

     Positive displacement blowers or Rotary air blower is used to move gas or air for a variety of applications.

     Positive displacement blowers are almost similar to positive displacement pumps, which squeezes fluid that in turn increases pressure.

    Positive displacement blowers are preferred  over a centrifugal blower because a high pressure is required in a process.

  EX: Cycloidal or Lobe blowers

 Cycloidal or Lobe blowers:

Construction:

The general construction of a lobe blower consists of only two or three lobes as rotating parts. They run in close contact with each other and with casing to run efficiently.

Working principle:

It consists of two or three lobe impellers mounted on parallel shafts, rotating in opposite with in a casing closed at the ends by side plates. These blowers are constant volume machines and deliver a fixed discharge of air at a high velocity from the outlet.

cycloid blower 1

Advantages:

(1) They provide a large volume of flow which ranges from 30 to 15000m3/ hr.

(2) Sustainable energy efficiency

(3) Low maintenance time and costs

Disadvantages:

(1) Leakages between the lobes is possible

(2) It produces high noise during working

Centrifugal blowers:

Centrifugal blowers are also called as turbo blowers

Turbo blowers deliver gases at constant pressure, constant suction pressure, constant volume and at constant weight.

centrifugal blower 1

Principle:

In centrifugal blower the energy is transferred from a rotating shaft to air or gas. A pressure rise is achieved by adding kinetic energy to a continuous flow of air through the rotor or impeller.

Construction:

The construction of the centrifugal blower resembles a centrifugal pump. But in centrifugal blower the parts are made as light as possible and the size is smaller than the centrifugal pump it consists of a enclosed type impeller.

Applications:

(1) waste water treatment

(2) Flue Gas desulfurization and lead recycling

Disadvantages:

(1) The cost of the centrifugal blowers is high

(2) since the pressure developed is low, multistage centrifugal blower has to be used for generating high pressure

Prepared by

Sreenivasulu chenna

 

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