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PERFORMANCE OPTIMIZATION OF FORCED DRAFT FAN of UNIT #1 (BBGS)
Project Guide:Mr. Samir BandyopadhyaySenior Manager, Mechanical Maintenance DepartmentBudge Budge Generating StationCESC Limited
Presented By:Saikat Halder, Mechanical Engineering, IIEST, Shibpur
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Presentation layout
• Introduction• Fans• Air and Flue gas path• Governing Equations• Result and Discussion• Conclusion
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Introduction
• Forced Draft (FD) fans are used for supplying the combustion air into the furnace of a boiler.
• A good design of fan and its control system increases plant reliability by improving furnace pressure control and airflow control, which is most critical control part of combustion control system.
• In this report, the performance evolution, monitoring and optimization of Forced Draft fan of BBGS unit #1 has represented.
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Fans• Fans generate a pressure to move air (or gases) against a resistance caused
by ducts, dampers, or other components in a fan system.• Fans fall into two general categories: Centrifugal fan Axial flow fan• System characteristics• Fan characteristics
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Fan Characteristics Curve
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Air and Flue Gas path
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Measurement of various fan parameters
• Pressure of air at the discharge to each FD fan at different load.
• Flow of each FD fan at different load.
• Current requirement (Amps) of each FD fan at different load.
• Inlet damper position of each FD fan at different load.
• The average temperature of the air passing through the FD Fan.
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Governing equations
• The equation for determining total efficiency is:
• Power input to the motor
• Power input to the shaft
• Air density
( all the equations are taken from the documents of Bureau of
Energy Efficiency)
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Result
0 20 40 60 80 100 120 140 160 180 200 220 240 260 2800
50
100
150
200
250
300
350
400
450
500
550
600
650
70%80%
90% 100%
Discharge (mᵌ/sec)
50%
Design Point
Hea
d (m
m o
f WC
)
60%
H-Q Curve of FD Fan-A
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Result contd.
0 20 40 60 80 100 120 140 160 180 200 220 240 260 2800
50
100
150
200
250
300
350
400
450
500
550
600
650
Discharge ( mᵌ/sec)
Head
( m
m o
f WC
)
80%90%
100%
60%70%
Design Point
H-Q Curve of FD Fan-B
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Result contd.• Both fan operation
FD Fan-A
FD Fan-B
• Single fan operation FD Fan-A
Load (MW) Volume Flow Rate (mᵌ/sec) Head (mm of WC) Power (kW) Efficiency (%)
150 (60%) 97.8 256 840.8 29.2
175 (70%) 105.1 255 849.9 30.9
200 (80%) 115.7 274 877.3 35.4
225 (90%) 119.5 288 895.6 37.7
250 (100%) 129.0 303 913.9 40.8
Load (MW) Volume Flow Rate (mᵌ/sec) Head (mm of WC) Power (kW) Efficiency (%)
150 (60%) 113.5 260 831.6 34.8
175 (70%) 121.5 261 859.0 36.2
200 (80%) 136.1 289 886.4 43.5
225 (90%) 143.2 292 913.8 44.9
250 (100%) 143.0 299 913.8 45.9
Load (MW) Volume Flow Rate (mᵌ/sec) Head (mm of WC) Power (kW) Efficiency (%)
125(50%) 165.5 200 1017.9 31.9
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Result contd.• Design Efficiency of both the fan: 74.53%
• Both fan operating
FD Fan-A 28.3% to 41.9%
FD Fan-B 34. 8% to 47.6%
• Single fan operating (FD Fan-A) 30% to 35%
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Remedial suggestions
• Design modifications by consulting with the manufacturer or some consulting engineering firms.
• Use of Variable Frequency Drives(VFDs)
• Use of fluid coupling with variable speed
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Conclusion• The capacity of the FD Fan was considerably higher than required.
• The FD fans operated within a low power output area over a long period of time, thereby increasing power consumption and increasing costs of operating the unit.
• Constant speed of the motor creates inefficient operation.
• Use of dampers to control the air flow is a inefficient manner of flow control.
• Modification in the design of the fan, use of use of Variable Speed Drives (VFDs), use of fluid coupling with variable speed are some corrective measures for improvement.
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Thank You
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