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Ash Handling and Dust Collection

Ash Handling and Dust Collection

The disposal of ashes from a large capacity power station is of some importance as it is 10 to 20% of the coal used. A 200 MW capacity power plant using Indian coals produces as large as 60,000 tons of ash per annum. This quantity of ash is equivalent to a height of 1.5 metres covering four hectares area. This shows that a power plant of 200 MW capacity requires 160 hectares area during its life time if the ashes produced are dumped at the site of the plant.

The ashes should be discharged and dumped at a sufficient distance from the power plant because of following reasons

(1) The ash is dusty, therefore irritating and annoying to handle.

(2) It is sufficiently hot when it comes out of the boiler furnaces.

(3) It produces poisonous gases and corrosive acids when mixed with water.

The ash handling is a difficult problem and sufficient attention should be given to design the ash handling plant. The difficulties encountered in the ash-handling plant layout are listed below:

(I) It forms clinkers by fusing together in large lumps which must be broken before given to any reasonably sized conveying equipment.

(2) The ash produced is abrasive and will wear out the conveyor parts on contact with it therefore special conveyors must be designed to handle the ashes.

(3) The ashes must be cooled before carrying from the furnace collecting hoppers as it is very difficult to carry hot ashes.