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Fans & Blowers

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Fans & Blowers

Introduction

Types of fans and blowers

Assessment of fans and blowers

Energy efficiency opportunities

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Energy Efficiency Opportunities

1. Choose the right fan

2. Reduce the system resistance

3. Operate close to BEP

4. Maintain fans regularly

5. Control the fan air flow

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a) Dampers

b) Pulley change

c) Inlet guide vanes

d) Variable pitch fans

e) Variable speed drives (VSD)

f) Multiple speed drive

g) Disc throttle

h) Operating fans in parallel

i) Operating fans in series

5. Control the Fan Air flow

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a) Dampers: reduce flow and increase

upstream pressure

Types:

• Louvered Damper

• Radial Damper

• Vortex Damper

• Variable Inlet Vane (VIV)


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a) Dampers:

• Advantages/ Disadvantages…

…..on Blog…..


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b) Pulley change:

• Pulley & Belt Drives

• Possible to have various combinations of

pulleys (sheaves) & belt drives on the

motor and the fan to vary the fan speed

• Driven by a single-speed motor.

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b) Pulley & Belt Drives:

• A convenient way of reducing the

rotational speed of fans

• usually designed to operate under 1,800

rpm

• The belt transfers the power from the

motor to the fan, and changes the fan

speed relative to the motor speed

according to the desired pulley ratio.

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b) Pulley & Belt Drives: Types of Drives

The four principal types of belts are:

• Flat belts;

• V-belts;

• Cogged V-belts; and,

• Synchronous belts.

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b) Pulley change: reduce motor/drive pulley

size


…..on Blog…..


(BEE India, 2004)

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c) Inlet guide vanes

• Create swirls in fan direction

• Reduce angle air and fan blades

• Lowering fan load, pressure, air flow


…..on Blog…..


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d) Variable pitch fans: changes angle

incoming airflow and blades


…..on Blog…..


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e) Variable speed drives (VSDs): reduce

fan speed and air flow

• Two types

• Mechanical VSDs

• Electrical VSDs (including VFDs)


…..on Blog…..


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e) Variable frequency drives

• Change motor’s rotational speed by

adjusting electrical frequency of power


…..on Blog…..


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f) Multiple speed drive

• Changes fan speed from one speed to

other speed


…..on Blog…..


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g) Disc throttle:

Sliding throttle that changes width of

impeller exposed to air stream


…..on Blog…..


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h) Operate more fans in parallel (instead of

one large fan)


…..on Blog…..


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i) Operate fans in series

• Advantages

• Lower average duct pressure

• Less noise

• Lower structural / electrical support required

• Disadvantages

• Not suited for low resistance systems


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5. Controlling the Fan Air Flow

Comparing

Fans in

Parallel

and Series

(BEE India, 2004)

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(BEE India, 2004)

5. Controlling the Fan Air Flow

Comparing

the impact of

different types

of flow control

on power use

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Some Clues:

• High operating cost;

• High maintenance cost;

• High level of noise;

• High air leakage in ducting or system;

• Inadequate air flow through certain

branches; or

• Inability to adjust flow rates according to

production needs.

Identification of Inefficient F & Bs

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caused by…

• inefficient fan operation,

• improper fan selection (usually oversizing

for the application),

• operation in the wrong pressure range,

• poor system design,

• wasteful air flow control choices and

• operation when not needed.

High operating cost

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• Belt slippage is not only wasteful of

energy, but also results in excessive

wear and early failure of the belt and

pulleys.

• Belt over-tightening results in higher

energy consumption, excessive wear on

the bearings and early belt and bearing

failure.

High maintenance cost

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• Soft starters can extend fan motor life

by keeping the motor temperature lower.

• Variable frequency drives (VFDs) are

also commonly used to soft start fans by

gradually bringing fan speed up to

operating conditions.

High maintenance cost

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• oversized fans, or

• with the wrong type of fan for the

application

High level of noise

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Due to poorly designed or maintained

ducting or equipment, stuck dampers or

other reasons.

The result is more fan power required.

High air leakage in ducting or

system

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Due to inadequate balancing and duct

configurations.

Inadequate air flow through certain

branches

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The use of dampers to block or by-pass air

flow is very inefficient and causes more

power to be drawn by the fan.

Inability to adjust flow rates as per

need

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When air flow requirements change with

time…

..a single fan may be forced to operate far

away from the BEP over long periods of

time…

reduce the fan efficiency.

What are the options to avoid it??

How to avoid overdesign in Fans

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options :

• Multiple fans in series or parallel;

• Replacing fans with a more appropriate

type for the load;

• Better matching of fans/blowers to motors


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• In parallel or series?- depends on

requirement

•Installed in series close to each other:

increase pressure locally or

•Installed in series far apart: increase

pressure in different parts of the ductwork.

• Installed in parallel : varying the air

flow rate.


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• In parallel or series?- depends on

requirement

• Fans in series in an induced-draft/ forced-

draft configuration minimize the amount

of pressurization in a duct or an

enclosure.


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Training Session on Energy

Equipment

Fans & Blowers

THANK YOU

FOR YOUR ATTENTION

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