(B)LOWER
BLOWER
Blower is equipment or a device which increases the
velocity of air or gas when it is passed through equipped impellers. They are
mainly used for flow of air/gas required for exhausting, aspirating, cooling,
ventilating, conveying etc. Blower is also commonly known as Centrifugal Fans
in industry. In a blower, the inlet pressure is low and is higher at the
outlet. The kinetic energy of the blades increases the pressure of the air at
the outlet. Blowers are mainly used in industries for moderate pressure
requirements where the pressure is more than the fan and less than the
compressor.
APPLICATION OF BLOWER
- Blowers are used in industries when there is a requirement for larger volumes of air flow at higher pressures. A fan with higher pressure ratio (output pressure / input pressure) can be called as a blower provided it produces pressures as high as 1.20 kg/cm2.
- Positive displacement blowers are often used in pneumatic conveying, and for sewage aeration, filter flushing, and gas boosting, as well as for moving gases of all kinds in the petrochemical industries.
- Like fan systems, blowers are widely used in industrial processes where a constant flow of air/gas is needed at higher pressures such as conveying material in dust collector systems, combustion air for burners, drying & cooling, general ventilation & circulation of air and so on.
- Blowers with higher efficiency are also used in industrial vacuum systems where suction or negative pressures are required.
- Therefore, blowers(along with compressors and fans), largely cover Municipal, Manufacturing, Oil & Gas, Mining, Agriculture Industry for their various applications, simple or complex in nature.
- These are available from
various manufacturers in different designs. Few of the well-known brands are
Roots, Hoffman, Bosch, Sutterbuilt ,Sullair and Joy.
TYPES
1. Positive Displacement Blowers
- A positive
displacement blower has a function that’s straightforward yet effective. Air or
gas enters through an expanding section on one side and exits through a
decreasing section on the other side. To put it simply, positive displacement
blowers trap and then release the air.
- Positive displacement
blowers maintain a constant speed and flow regardless of changes in pressure.
You can use these blowers to move both air and neutral gases.
- Rotary lobe blower
I.
One type of positive
displacement blower is the Rotary lobe blowers which consist of two rotors
spinning in opposite directions. The blower sucks in air, and the lobes spin
the air around before pushing it out.
II.
One of the best
aspects of rotary lobe blowers is they produce a high volume of air, which is
crucial for vacuum systems. However, this air has low pressure (about 15 psi),
so a rotary lobe blower is not the best choice for applications that require
high pressure.
III.
Another benefit to
rotary lobe blowers is that they take little maintenance and work with most
blower systems.
IV.
But they do let some
air escape, so they are not the most energy-efficient blower option. They are
incredibly loud but can be quieted with silencers.
2. Helical Screw Blowers
- Each helical screw
blower has a main rotor with two lobes. This rotor fits into the flute of a
second rotor. The two rotors turn in a helical pattern that is carefully timed
so they do not contact each other.
- Helical screw blowers
typically produce air at higher pressures than rotary lobe blowers do. They
also perform more quietly than rotary lobe blowers.
- These intricate
blowers are energy-efficient options as well. The sealed design of helical
screw blowers leads to a smooth air flow and limited air leakage.
- Helical screw blowers
are used to move both air and gas, depending on the application
3. Centrifugal Blowers
- Centrifugal blowers
are the most common blowers used in ventilation systems. They’re also used to
transport gas and control air pollution.
- When an air stream
passes through this blower’s rotating impellers, it increases in both speed and
volume. Centrifugal blowers actually change the airflow’s direction as well.
The air or gas enters the fan wheel, turns 90 degrees, and speeds up before
exiting the blower.
- A centrifugal blower
is an ideal tool to maintain a continual gas transfer. When gas passes through
a centrifugal blower, it increases in kinetic energy. When the gas exits the
centrifugal blower, new gas enters to normalize the gas pressure.
- One specific kind of centrifugal
blower is called a multistage centrifugal blower. This blower is used for
creating pressure, circulating air, and creating suction. It can handle high
pressure and high flow rates and is ideal for creating high pressure from small
volumes of air. You can use it for fish tank aeration, gas meter testing, and
even powering artificial lungs.
4. High Speed
Blowers
- If you need a blower
with a significantly high pressure and flow, look for a high speed blower.
These electrical blowers run via a motor. They have impellers at each side of
the shaft to provide double suction.
- High speed blowers can
reach a pressure up to 25 psi and a flow up to 15,000 m3 per hour.
5. Regenerative Blowers
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