of Ash handling system
Boilers burning pulverized coal (PC) have bottom furnaces.
The large ash particles are collected under the furnace in a water-filled ash
hopper, Fly ash is collected in dust collectors with either an electrostatic
precipitator or a baghouse. A PC boiler generates approximately 80% fly ash and
20% bottom ash. Ash must be collected and transported from various points of
the plants as shown in figure. Pyrites, which are the rejects from the
pulverizers, are disposed of with the bottom ash system. Three major factors
should be considered for ash disposal systems.
Needs for water and land are important considerations for
many ash handling systems. Ash quantities to be disposed of depend on the king
of fuel source. Ash storage and disposal sites are guided by environmental
Figure: Layout of ash collection and
The sluice conveyor system is the most widely used for
bottom ash handling, while the hydraulic vaccum conveyor (figure) is the most
frequently used for fly systems.
Figure: Layout of ash handling
Bottom and slag may be used as filling material for road
construction. Fly ash can partly replace cement for making concrete. Bricks can
be made with fly ash. These are durable and strong.
Mechanical means are required for the disposal of ash. The
handling equipment should perform the following functions: 1. Capital
investment, operating and maintenance charges of the equipment should be low.
2. It should be able to handle large quantities of ash. 3. Clinkers, shoot,
dust etc. create troubles. The equipment should be able to handle them
smoothly. 4. The equipment used should remove the ash from the furnace, load it
to the conveying system to deliver the ash to dumping site or storage and
finally it should have means to dispose of the stored ash. 5. The equipment
should be corrosion and wear resistant.
Figure: Ash handling equipment