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BOTTOM ASH DEASHING
Presented By
Raghu, Satish, Ramesh
Diploma Trainees
2
Bottom Ash Deashing
 What is Bottom Ash?


Solid Mineral Residue (Ash) Collected at Bottom of the Furnace that
results from burning of coal in Boiler
Indian coal contains 40% of ash content, out of which 20% is Bottom Ash,
80% is Fly Ash.
 Typical Ash Composition : SiO2, Al2O3, Fe2O3, CaO , MgO etc.
 “Ash is Necessary Evil”
 A typical 2000MW Power Station produces 9000 – 12000 tons
Bottom Ash per day
 Frequency of Deashing - every 3 hrs at 500MW, 5 hrs at 275MW
3
Ash Volume
Bottom Ash
Fly Ash
4
Bottom Ash Hopper Arrangement
5
Bottom Ash Deashing Scheme
Bottom Ash Hopper
Ash Slurry Sump
B1
B2
A1
A2
Slurry Pumps
BAHP
Water
Ash Water Sump
Ash Dyke
6
BAHP Scheme
Our BAHP line arrangement consists of a Main Isolating valve (which we always keep open
in normal condition) and individual clinker grinder jet pump valves will be opened during
Deashing time and close after Flushing complete.
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To Ash Slurry Sump
To Ash Slurry Sump
Bottom Ash Deashing Procedure
BAHP I/S
BAHP STANDBY
8
Bottom Ash Handling System - Parts
 Bottom Ash Hopper
 Seal Trough
 Feed Gates
 Clinker Grinders
 Ejectors/Jetpumps
 Bottom Ash Overflow Tank
 Hopper, Seal Trough Filling Lines
9
Bottom Ash Handling System
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Check 10.5m peepholes
• Check Ash Buildup
• Observe Sound
11
Check Overflow Lines Chokage
Overflow Lines
Overflow Tank
Overflow Tank Level
Check Auto Start of Overflow Pumps
Inform AHP Control Room
 Obtain Clearance for Bottom
Ash Deashing
14
Check Seal Trough, Refractory Cooling Water
Seal Trough Filling
Water Valve
Ensure Seal Trough
is Overflowing
Refractory Cooling Sources of Refractory,
Seal Trough Water:
Water Valve
1. BAHP Header
2. Fire Water
Open Discharge Gate
Discharge Gate
BAHP Lineup
At a time only two jet pumps are charged
Ensure Flushing is Completed in Previous Deashing Lines
17
Charge BAHP water to Jetpump
BAHP Line Vents
Pressure Gauge
Jet Valve
BAHP Main Isolating Valve
Observe BAHP Header Pressure
8
Charge Grinder Seal Water
Sources of Seal Water:
1. BAHP Header
2. Fire Water
Seal Water Pressure
Gauge
Seal Water Valve
Start Clinker Grinder Motor, Observe any abnormality
Fluid Coupling
Clinker Grinder Motor
Clinker Grinder
Clinker Grinder
Chain
Open Feed Gate
Feed gate Open Indication
After Taking Clearance from
AHP Control Room, Feed gate
has to be opened
Check Chamber Vent
23
Local Operation Panel
CG Current
Overflow Tank Level
Discharge Gate Operation
Feed Gate Operation
Check Discharge
By touching the Discharge Pipe
Also by checking at Ash Slurry
Sump end
Check Bottom Ash Hopper Level
Observe W Portion Split
Hopper Flushing
Individual
Flushing
Water
Valve
BAHP Flushing Water Valve (Main)
Ensure Empty of Hopper
Ensure Grinder
Chamber is Empty
Close Feedgate
after that
Hopper Filling
BALP Filling Valve
Firewater Filling Valve LHS
Firewater Filling Valve RHS
Discharge Pipe Flushing
 Atleast 15minutes Line flushing should be
done after Bottom Ash Deashing
31
Special Cases
 Grinder Jam
 Grinder Not Discharging
Back Flushing Procedure
To Ash Slurry
Sump
4
8
Discharge Gate
Feed Gate
33
Migratory Birds at NTPC Dadri
Thank You
NTPC Ramagundam
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