Ash Handling and Ash Water Recirculation System shall consist of the following sub systems:
Bottom Ash and Economiser Ash Handling System
Jet pump and Water Impounded Hopper System – An intermittent system consisting of water impounded hoppers, clinker grinders, jet pumps etc.
OR
Submerged Scrapper Conveyor and dry type hopper System – A continuous system consisting of dry type Bottom Ash hoppers, submerged scrapper conveyors, clinker grinders, bottom ash slurry trench, BA Slurry Transportation Pumps etc.
Economiser, Air preheater and duct hopper ash shall be handled in wet form. Economiser ash slurry from economiser hoppers shall be led to bottom ash hopper and the same shall be discharged along with bottom ash slurry into slurry sump of the Bottom ash slurry disposal pump house. Air preheater and duct hopper ash shall be collected at an intermediate slurry transfer tank and shall be intermittently discharged along with bottom ash slurry into slurry sump of the Bottom ash slurry disposal pump house
Bottom Ash Hopper Overflow Water System
Over flow water from bottom ash hopper is to be reused in ash handling system. For this purpose overflow tank, settling tank & surge tanks, overflow water transfer pumps and sludge pumps shall be provided.
Dry Fly Ash Conveying system
Two alternatives for pneumatic conveying system have been specified for conveying of fly ash in dry form from ESP hoppers upto buffer hoppers. i.e. vacuum conveying system or pressure conveying system
Vacuum Conveying System
It shall consist of liquid ring vacuum pumps, material handling valves, cast iron and MS pipes, instrument air compressor etc.
OR
ii) Pressure Conveying System
It shall consist of screw compressors, air lock/pump tanks, ash intake & discharge valves, CI & MS pipes, instrument air compressors etc.
Ash Water System
Ash water system shall consist of bottom ash HP water pumps, BA LP water pumps, flushing water pump, fly ash HP water pumps etc.
Ash Disposal System
i) Bottom ash and economizer, Air preheater and Duct ash slurry disposal system
The bottom ash and economiser ash slurry from both the units, shall be transported by BA slurry pumps from bottom ash slurry pump house to ash dyke.
ii) Fly ash slurry disposal system
The fly ash collected in HCSD silos near chimney shall be mixed with water in an agitator tank at controlled rate to obtain the desired high concentration. This high concentration slurry shall be further pumped to Ash dyke
Dry Fly Ash Transportation system
The dry fly ash from the electrostatic precipitator hoppers shall be taken to buffer hoppers of each unit. The dry ash buffer hoppers shall be located adjacent to the ESP. Dry fly ash from buffer hoppers shall be transported either to HCSD silos located near the ESP of unit #1 or to storage silos located near the plant boundary. The dry fly ash transportation system shall be provided for each unit for transportation from buffer hoppers to the silos (HCSD/Storage). The user industries shall take the dry fly ash from storage silos either in closed tankers or in open tankers. The storage silos shall also have rail unloading facilities.
The system will consist of buffer hoppers, Transport air compressors, CI pipes, Structural steel silo, buffer hopper & silo aeration blowers, hydromix dust conditioners, telescopic chutes, booster & wash water pumps etc.
Ash water Recirculation system
Ash Water recirculation system shall be provided to reclaim the overflow water from bottom ash overflow lagoon to the ash water pump house
Seepage water recirculation system at dyke area, Fugitive dust suppression system at dyke area, Cooling Towers for equipment cooling water system, Air conditioning & ventilation are included in the scope of work.
Under electrical system, Motors, VFD,PLC etc. are included in the package
Under C&I system, instrumentation cables are included in this package. DCS based control system shall be procured separately under station control and instrumentation package.
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