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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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