Dry Ash Handling System for Power Plants

Abstract

The most commonly used wet ash handling system in which slurried ash is pumped to ash lagoons is compared with a relatively new dry ash handling system in which moistened fly ash and dewatered bottom ash are continuously transported to the disposal area and compacted. The proposed system for a typical 2,000 MW power plant features submerged drag bar conveyors under the boiler hopper and a system of fixed and movable conveyors. Two sets of independent conveyors are provided to enable conveyance of fly ash and bottom ash separately when required, and to minimize chances of complete breakdown of the system. These conveyors are fully enclosed to reduce noise and dust. Manned equipment is limited to bulldozers which spread and compact the ash. Problems in conveying, storing, and compacting ash are enumerated. Control of moisture content, use of suitable compactors, and provision of lined drainage courses in the ash pile are emphasized. Conveyor movements are shown with reference to a valley disposal area. As soon as the top of the ash pile is reached, it is covered with topsoil and seeded. Runoff to be treated is restricted to that over the exposed ash area by means of interception ditches.