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FANS & BLOWERS
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FANS & BLOWERS
Machines to move gases/ gases mixedwith small solid particles
Centrifugalfans
Axial flow fans
Operation of fan similar to that of pumps
Efficiency offans (40-70%)
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Fans & Blowers - Major EnergyConsumer
CementPaperPower PlantsSugar
Energy Consumption - 10 to 25%- Depending on Type of Industry
Substantial Energy Saving Potential -Installing VSDs
Upto 25%
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PUMPS/BLOWERS FORMULAE
Rpm Capacity
Head Rpm2
Power Capacity x head
Power Rpm3
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If rpm is reduced what happens to
Capacity
Head
Power
PUMPS/BLOWERS FORMULAE
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Types of Control
Damper - Most Popular Variable Speed Drive
Recirculation
Damper
VFC
VFD
Ideal
Power
Flow25 7550 100
100
75
50
25
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FANS HOROSCOPECHARACTERISTIC CURVE
n1 rpm
n2 rpmPower consumption
80%
76%74%
Volumetric flow
P
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FAN EFFICIENCY
Q x P
102 x (m) x kW(I)
- Pressure rise of the fan, mm WC
(m) - Motor efficiency
Q-Volume flow rate in m3/s
P
kW(I) - Motor Input Power
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FACTORS AFFECTING THEPERFORMANCE OF A FAN
RPMDiameter
Density
Temperature
Parameter Rpm Diameter Density Temperature
Volumetric n D3 - -capacity
Pressure rise n2 D2 r 1/TPowerconsumption n3 D5 r 1/T
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THROTTLING OF A FAN
Suction/Delivery
Why?
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THROTTLING - SUCTION
0 mm
-600 mm
-700 mm
Average pressure of fan =(10336 - 700) + 10336
2= 9986 mmWg
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THROTTLING - DISCHARGE+100
(120) mm
-600 mm
0 mm
Average pressure of fan =
(10336 - 600) + (10336 + 100)
2= 10086 mmWg
Average density higherpower consumption high
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POWER CONSUMPTION OF ANOVER SIZED FAN
Fan designed1,20,000 m3/hr
650 mmWg
Actual requirement 90,000 m3/hr
510 mmWg
10 mmWg
Damper 60%
-500 mmWg-720 mmWg
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Consumes - 289 kW
POWER CONSUMPTION OF A OVERSIZED FAN
Power 730 mm Wg x 90000 m3/hr
Pressure rise = 10 - (-720)= 730 mmWg
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CORRECT SIZE FAN
+ 10 mmWg
-500 mm Wg
Pressure rise = 10 - (-500)
= 510 mmWg
Power 510 mmWg x 90000 m3/hr
Consumes - 202 kW
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Energy Loss in Damper Control..
Pr
essure
Volume
N1 rpm
N2 rpm
Loss Across Damper
Required
720
510
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POTENTIAL IN OVER SIZE FAN
Energy saving potential in over sized fan
= x Power consumption
= x 289 kW = 87 kW
P across damper
Total pressure rise
220
730
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ENERGY AUDIT IN FANS &BLOWERS
Is it off the correct capacity/head?
Is the fan/blower really required?
How is the fan controlled?
Damper throttling
Guide vane control
Speed control
ENERGY AUDIT IN FANS &
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ENERGY AUDIT IN FANS &BLOWERS
Replacement by high hfan
What is the efficiency of fan?
Can the capacity/head be further finetuned?
Can the blower be interlocked with
process operation?
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Coal Mill Ventilation Fan SpeedReduction
+ 5 mm
50%
BF
-360 mm
-270 mm
38 kW
Pressure drop = 90/365 = 24%Head required = 0.76 times present head
rpm of ventilationfan reduced by10%
Savings Rs 1.34 lakhs
Investment Rs 5000
Payback 1 month
Belt driven
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INSTALL A LOWER RPM MOTORFOR VENTILATION FAN
+ 20 mmWg
-150 mmWg-50 mmWg
38 kW
+ 50 mmWg
Pressure rise of the fan = 200 mmWgNet p across damper = 65%
P 130 mm wg
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INSTALL A LOWER RPM MOTORFOR VENTILATION FAN (contd)
Power consumption by 75 kW/ 980 rpmmotor = 50 kW
Replace with 75 kW/980 rpm motor
Power consumed by the 150 kW/ 1440 rpmmotor = 100 kW
savings - Rs.8.00 lakhsInvestment Rs 2.00 lakhs
Payback 3 months
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Install right size fan for ESP
Fan Design 1, 10, 000 m3/ hr, 200 mm
Variable speed
Plant originally rated for 300 TPD, operating
at 450 TPD
Present operation
1, 48, 000 m3/ hr, 110 mm WC
110 kW
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110 148Quantity km3/hr
200
Head
(MM)110
CHARACTERISTIC CURVE
Des point -Eff. - 78 %
Op point
Eff. - 44 %
1000 rpm
740 rpm
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Install right size fan for ESP
Install right size fan
Capacity - 1, 50, 000 m3/ hr
Pressure - 125 mm
Annual Savings - Rs. 12.00 Lakhs
Investment - Rs. 10.0 Lakhs
Payback - 10 Months
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INSTALL HIGH EFFICIENCY FANFOR COOLER FAN #1
80%
Temperature32oC
Temperature55oC
550 mmWg
Fan inefficient = 54%Replaced with
high efficiency fan
Savings Rs 3.00 lakhs
Investment Rs 4.00 lakhs
Payback 16 months
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Install VFD for Boiler ID Fans
Present ControlDamper Based on Furnace DraughtEnergy Loss Across Damper
-60mm -110mm
50% ID Fan53kW
VFD-29kW
30TPH
Boiler
ESP VFD
PIC
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Install VFD for Boiler ID Fans..
Install Variable Frequency Drive (VFD)Control by Varying SpeedDamper - 100% Open
Power with damper = 53 kWPower with VFD = 29 kW
Savings = 24 kW
Annual Savings - Rs. 7.76 LakhsInvestment - Rs. 6.85 Lakhs
Payback - 11 Months
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ID Fans Operation
ESP
ID Fan
ID fan is operated with fluid coupling & IGVControl
System studied in detail
135 m3
/sec, 236 mmWg, 645 KW Overall efficiency52%
Where to attack?
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ID Fans Operation
ID fans power consumption
Motor losses, VFC and fanThese need to be looked into
Motor VFC FanInput Power
100%
645 kW
Fluid Power52%333 kW
hLoss6%
38.7 kW
hLoss20.46%129 kW
hLoss21.54 %144 kW
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ID Fans Operation
Loss in Variable fluid Coupling
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% loss is highest at 66% speed For this fluid coupling few suppliers
Loss estimated at 132 KW
Calculated loss also 127 KW
How to Avoid / Reduce this?
Replace VFC with high efficient VSD
Operate VFC with higher speed
not possible
ID Fans Operation
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Based on ID fan characteristic curve
Reduction in speed
Doesnt affect operating
efficiency much
ID Fans Operation
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How to proceed now?I Step
Reduce IGV Control and lower speed of fan &control through VFC
Explore the option of putting VFC in closed
loop with draught
Discuss with suppliers & collect loss curves
At 40% speedclosed loop should be
possible
Replace with quick response actuator Operating in many cement plants for critical
fan applications
Soda recovery boilers in paper plant
ID Fans Operation
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How to proceed now?II Step
Replace VFC with a 6.6 KV VFD
Excellent long term option
HT VFDs installed already
Chettinad cement6 drives- recently
Tata powerVFD for ID fan
Operating for last 8 years
ChinaRecent years several HT VFDs
installed
ID Fans Operation
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ID Fans Operation
Option -1
Annual Saving - Rs 30.2 Lakhs
Option -2
Annual Saving - Rs 198 Lakhs
Investment - Rs 375 Lakhs
Payback period - 23 Months
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To Sum Up
Fans & Blowers -Energy Savings
Industry
Implement
Benefit
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C f d ti f I di I d t