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CHIMNEY
BOILER
C
OAL
MILL
ID FAN
PA FAN
FUEL OIL TANK
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CONSTRUCTIONALLY ESP CONSISTS OF
POWER SUPPLY UNIT
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Emitting electrode
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Collecting & Emitting system
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DESIGN PARAMETERS OF ESPAsh percentage in coal.
Inlet dust concentration
Outlet dust concentration
Flue gas flowTotal collecting area
Specific collecting area
Flue gas velocityPressure drop
Temperature drop
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(Principle of ash Separation)
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Field charging Saturation charge
qs
CORONA
Corona generation
It is difficult to charge small size ash particle
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HOW IT LOOKS
Corona is generated in spots along the wire at critical voltage
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WHAT HAPPENS...
High resistivity ash leads to back corona
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EFFECTS
Back corona reduces precipitator voltage
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HIGHER THE TEMPERATURE LOWER ISTHE OPERATING VOLTAGE.
HIGH TEMPERATURE INCREASES ASHRESISTIVITY
10DEG. CENT. RISE IN TEMPERATURE
EFFICIENCY IS REDUCED BY 2-3%.
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i i i i i l i
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Effect of Resistivity on Wm
0
2
4
6
8
10
12
14
16
18
1.00E+09 1.00E+10 1.00E+11 1.00E+12
Resisticvity(ohm.cm)
Wm(cm/s)
Wm(cm/s)
Resistivity vs Migration Velocity
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COARSE PARTICLES ARE EASIER TOCOLLECT THAN FINE PARTICLES.
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Effect of particle size on efficiency
91
92
93
94
95
96
97
98
99
100
101
0 2 4 6 8 10 12
Particle size(Microns)
Efficiency
Efficiency
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HIGHER QUALITY OF FLOW CANADVERSLY AFFECT THE EMISSION
PERFORMANCE.AIR INGRESS INCREASES FLOWDETRIMENTAL TO PERFORMANCE
HIGHER FLOW REDUCES SPECIFICCOLLECTION AREA.
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POOR ALLIGNMENT CAUSES LOW
VOLTAGE A COMMON REASON FORPOOR PERFORMANCE.
POOR ALLIGNMENT CAN RESULT INFOULING OF THE ELECTRODE AND IMPAIRPRECIPITATION
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REGULAR DISLODGING COLLECTEDASH FROM COLECTING PLATES
ENSURES GOOD PERFORMANCE.HOPPERS ARE NOT MEANT FORSTORAGE. ASH BUILD UP CAN AFFECT
THE ELECTRODE ALLIGNMENT ANDCAUSE MECHNICAL DAMAGE TO THEELECTRODE AND RAPPING SYSTEM.
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UNEQUAL DISTRIBUTION LEADS TOOVERLOADING AND REDUCTION IN
SPECIFIC COLLECTION.AFFECTS COLLECTING ELECTRODE.
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Air ingress:
- increases flow reduces percentage
moistures.- moisture can aid conduction in ashlayer can improve operating voltage.
Milling system:- Particle size is dependant on millingsystem.
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HIGHER FLUE GAS VELOCITY REDUCESTREATMNET TIME
AFFECTS MIGRATION VELOCITYAFFECTS LIFE OF COLLECTINGELECTRODE
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INTERMITTENT CHARGING
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Base charge avoids saturation of transformer
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Water washing ESP fields ensurescomplete surface cleanness of emitting,
collecting electrodes & and ashcollecting surface
Removes sticky layer of ash and oil
which is the cause of back corona
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