Coal Storage – Handling Issues

In a coal based captive thermal power plant, coal is received from coal blocks/Mines by means of railcars or barges. Then the Coal is dropped in a coal yard and usually stored in stockpiles. Reclaiming of coal from stockpile is done using an automatic reclaimer/stacker consisting of reclaim tunnel hoppers and feeders. After that Coal is conveyed to the crusher house for coal crushing and  transferred to belt feeders from where it is fed to the boiler.

Although many handling issues encountered in bulk storage but in case of coal storage or lignite storage, followings are the major handling issues to be faced while operating the boiler:

• The most common problem in operating coal under coal storage sheds is flow blockage. It largely depends upon bulk density, particle size and moisture content in the coal.
• Sometimes while handling, coal remains stagnant outside the feeding channel which has the tendency to combust spontaneously. Such Stagnant material may pose threat to fire.
• When material discharge from conveyor belt to the chutes for a long time, the friction of material with chute surface increases and thereby reduces the velocity of steam coming from the boiler.
• Boiler efficiency is mainly depended on presence of fuel properties in coal like hydrogen, moisture, and various other fire supporting elements in coal. To sustain excellent boiler efficiency, we have to keep losses (due to absence of such fuel properties in coal) to their minimum extent.
• Few other factors responsible for sustaining maximum boiler efficiency are ‘keeping optimal air level’, ‘keeping the fineness of coal to required level’, ‘proper rotation of coal in power plant to avoid combustion’ and more.