Chapter: Mechanical and Electrical : Power Plant Engineering : Coal Based Thermal Power Plants
Classification of Ash Handling System
Classification
of Ash Handling System
i) Hydraulic system
ii) Pneumatic system
iii) Mechanical system
The commonly used ash discharge
equipment is as follows:
i) Rail
road cars ii) Motor truck iii) barge
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. It is generally used in large power
plants. Hydraulic system is of two types, namely, low pressure hydraulic system
used for intermittent ash disposal figure. Figure shows hydraulic system.
Figure:
Hydraulic system
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 to 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.
Water jetting of ash is shown in figure. In this method a
low pressure jet of water coming out of quenching nozzle is used to cool the
ash. The ash falls into trough and is then removed.
Pneumatic System
In this system ash from the boiler furnace outlet falls
into a crusher where a lager 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.
Figure: Pneumatic system
Mechanical system
Figure: Mechanical system
Figure shows a mechanical ash 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 banker with the help of trucks.
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