2. Ash
Ash is the residue remaining after the coal
is incinerated.
Composition of Ash:
- SiO2 .Al2O3.Fe2O3.CaO. MgO
3.
4. Ash Handling System
The ash handling system handles the ash by
bottom ash handling system, coarse ash
handling system, fly ash handling system, ash
disposal system up to the ash disposal area and
water recovery system from ash pond and
Bottom ash overflow.
5. Parts of Ash Handling System
Bottom Ash Handling System
Coarse Ash (Economizer Ash) handling
system
Air Pre Heater ash handling system
Fly ash handling system
Ash slurry disposal system
6. Bottom Ash Handling System
Bottom ash resulting from the
combustion of coal in the
boiler falls into the over
ground, refractory lined, water
impounded, maintained level,
double V-Section type/ W type
steel- fabricated bottom ash
hopper having a hold up
volume to store bottom ash and
economizer ash of maximum
allowable condition with the
rate specified. The slurry
formed is transported to slurry
sump through pipes.
7.
8. Coarse Ash (Economizer Ash)
handling System
Ash generated in Economizer hoppers is evacuated
continuously through flushing boxes.
Continuous generated Economizer slurry is fed by
gravity into respective bottom ash hopper pipes with
necessary slope.
9. Air Pre Heater ash handling system
Ash generated from
APH hoppers is
evacuated once in a
shift by vacuum
conveying system
connected with the
ESP hopper vacuum
conveying system.
10. Fly Ash Handling System
Fly ash is considered to be collected in ESP Hoppers.
Fly ash from electrostatic precipitators or fabric bag filters (or
sometimes both), located at the outlet of the furnace and before
the induced draft fan, is extracted by Vacuum Pumps.
11. •Electrostatic precipitators or fabric bag filters (or sometimes
both) located at the outlet of the furnace and before the
induced draft fan.
•Generally, the fly ash is pneumatically transported to storage
silos for subsequent transport by trucks or railroad cars
Figure: Fly-Ash Washing
12. The ways of fly ash utilization include
•Concrete production, as a substitute material for Portland
cement and sand
•Embankments and other structural fills (usually for road
construction)
Waste stabilization and solidification.
•Cement clinkers production - (as a substitute material for clay)
•Mine reclamation
•Stabilization of soft soils
•As Aggregate substitute material (e.g. for brick production)
•Mineral filler in asphaltic concrete
•Agricultural uses: soil amendment, fertilizer, cattle feeders, soil
stabilization in stock feed yards, and agricultural stakes
•Loose application on rivers to melt ice
•Loose application on roads and parking lots for ice control
•Other applications include cosmetics, toothpaste, kitchen
counter tops, floor and ceiling tiles, bowling balls, etc
13. Ash Slurry Disposal System
Bottom Ash slurry, Fly ash slurry and the Coarse
Ash slurry shall be pumped from the common ash
slurry sump up to the dyke area which is located at a
distance from Slurry pump house.
14.
15. Requirement of Ash Handling
System
In Thermal Power Plant’s coal is generally
used as fuel and hence the ash is produced
as the byproduct of Combustion.
Ash generated in power plant is about 30-
40% of total coal consumption and hence
the system is required to handle Ash for
its proper utilization or disposal.