A huge quantity of ash is produced in central stations, sometimes 10 to 20% of the coal burnt in a day. In large power stations hundreds of tonnes of ash may have handles every day.
Handling of ash includes
Its removal from the furnace.
Loading on the conveyor and delivery to the fill or dump from where it can be disposed off.
A good ash handling plant should have the characteristics
It should have enough capacity to cope with the volume of ash that may be produced in a station.
It should be able to handle large clinkers, boiler refuse, soot, etc.,
It should be able to hot wet ash effectively and with good speed.
The plant should not cost much.
The operation charges should be minimum possible.
The operation of plant should be noiseless as much as possible.
The plant should be able to operate effectively .
Should have high rate of handling.
Ash handling equipments
The following equipment are used commonly for ash handling.
Bucket elevator
Bucket conveyor
Belt conveyor
Pneumatic conveyor
Hydraulic sluicing equipment
Trolleys or rail cars
Ash handling system
The modern ash handling system are classified into four groups. These are
Mechanical handling system
Hydraulic system
Pneumatic system
Steam jet system
i.Mechanical handling system
In this system ash cooled by water seal falls on the belt conveyor and is carried out continuously to the bunker. The ash is then removed to the dumping site from the ash bunker with the help of trucks.
ii.Hydraulic System
In this system, ash from the furnace grate falls into a system of water possessing high velocity and is carried to the sumps.
In this method water at sufficient pressure is used to take away the ash to sump. Where water and ash are separated.
The ash is then transferred to the dump site in wagons, rail cars or trucks. The loading of ash may be through a belt conveyor, grab buckets.
If there is an ash basement with ash hopper the ash can fall, directly in ash car or conveying system.
iii. Pneumatic system
In this system ash from the boiler furnace outlet falls into a crusher where larger ash particles are crushed to small sizes.
The ash is then carried by a high velocity air or steam to the point of delivery. Air leaving the ash separator is passed through filter to remove dust etc.
So that the exhauster handles clean air which will protect the blades of the exhauster.
iv. Steam jet system
In this method a low pressure jet of water coming out of the quenching nozzle is used to cool the ash. The ash falls into a trough and is then removed.
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