Ammonia Dosing
Ammonia Dosing
Ammonia Dosing
DEFINITION:
Ammonia helps to reduce resistivity of fly ash resulting in better ionization of the
particles and increase in collection efficiency of ESP fields.
STATUTORY LIMIT:
SPM : 150mg/Nm3.
SOX: 2000mg/ Nm3.
NOX: 750 mg/ Nm3.
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Transformer e
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mA KV
+ Positive Ions e
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e Negative Ions e +
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e Free electron +
e e e e e e
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WORKING PRINCIPLE IN DETAIL:
1) Step-up Transformer increases output Voltage from 415 V to 55 KV or
more according to the design criteria of ESP.
2) Output AC voltage is converted to DC through rectifier banks.
3) (+) ve side is connected to collecting plates and (-) ve side is connected to
discharge electrodes as shown if figure above.
4) When ash particles pass between collecting and discharge electrodes, due to
high electro-static field, the ash particles are ionized (negatively charged)
and attracted towards collecting plates where particles are collected.
5) After formation of sufficient thickness of ash particles on collecting plates,
collecting electrodes are hammered by continuous/intermittent rapping
mechanism.
6) Major portion of the Ash particles are thus collected in the hopper below
and a small quantity is carried over to the next fields due to velocity of flue
gas inside the ESP. Higher flue velocity increases re-entrainment of ash to
next fields.
7) Discharge electrodes are also hammered intermittently by another rapping
mechanism to dislodge the positively charged particles, which are collected
on discharged electrodes.
1000
800
600
400
200
0.05 0.5 2 5 10
Mass Mean Diameter (Micron)
Dry Air
7% H2O by volume
1010
25% H2O
0 10 20 30 40 50
Voltage in KV
% of COLLECTION in ESP FIELDS
at Different position
ESP FIELDS
100% TO 0.16%
GAS FLOW Dust 20% 4% 0.8% 0.16% STACK Dust
Burden Burden
ASH HOPPER
Caution:
Higher injection rate of NH3 may result ash to clinging to the Plates of ESP,
reducing the Plate rapping infecting.
SCHEMATIC DIAGRAM of
AMMONIA DOSING SYSTEM
Flow meter
Pressure gauge
Solenoid valve
Ammonia Cylinder
Isolating valve
Conveying Air
Manual control valve from Air Heater
EXPERIMENTATIONS TO REDUCE SPM
by AMMONIA DOSING IN ESP
AT TITAGARH GENERATING STATION
Clean dust burden at ESP Outlet 0.13 gm/Nm3 0.147 - 167 gm/Nm3
350
300
250
200
150
100
50
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
125
105 Injection
MILL CUT-IN
stopped
85
65
45
25
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
TIME
Av. SPM
RESULTS:
500 474.6
434.22
400
CONSUMPTION OF AMMONIA:
Generation Division
Online
SPM
Hosted From TGS Server By Environmental Cell
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