ASH HANDLING PLANT

Description of ash handling plant in thermal power plant operation.

1. Ash Handling System Ntpc-BRBCL (250*4) MW Submitted by : Aditya Anand Medha Mehta Abhijeet Bouri Sourav Mondal

2. What is ash ? Ash , also known as ember or clinker, is defined as the powdery residue left after something has been burned off Generally, it denotes the mineral content that is mostly left after combustion.

3. Bottom Ash Bottom ash  is part of the non-combustible residue of combustion in a furnace or incinerator. It is a Ash generated below furnace of steam generator In an industrial context, it usually refers to coal combustion and comprises traces of combustibles embedded in forming clinkers and sticking to hot side walls of a coal-burning furnace during its operation The clinkers are poked or just fall by themselves into the water, cooling down eventually Can be used in road construction and as a component of concrete

4. Fly Ash Fly ash is ash that comprises of fine particles carried alongwith flue gases. All types of fly ash includes substantial amounts of silicon dioxide and calcium oxide Particle size from .5µm to 100µm Component Bituminous Subbituminous Lignite SiO2 (%) 20-60 40-60 15-45 Al2O3 (%) 5-35 20-30 20-25 Fe2O3 (%) 10-40 4-10 4-15 CaO (%) 1-12 5-30 15-40 Data credits: fly ash systems , Max Ophulus , version 3

5. Data credits: https/:jnfnjj23jkf/fly-ash-production/census/1123hfn

6. Data credits:https :/ggrfjdjsn23/fly-ash- utlilization // countrywise //data census/334?bf

7. What is Ash Handling System ? The ash handling system handles the ash by Bottom ash handling system , coarse ash handling system , fly ash handling system , ash disposal system up to the ash disposal area and water recovery system from ash pond and bottom ash overflow

8. Parts of Ash handling System Bottom Ash handling system Coarse Ash (Economizer Ash) handling system Air Preheater ash handling system Fly Ash handling system Ash Slurry disposal system

9. Challenges of Ash handling Indian coal has high and inconsistent amounts of ash Ash handling is legally required to be environmentally friendly System has to be reliable with minimum maintenance problems System must be energy efficient

10. Ash Handling Systems

11. Wet Ash handling System The free falling Ash from boiler furnace is collected and stored in a ‘W’ shaped water impounded bottom ash hopper provided below boiler furnace for its periodic removal twice in a shift of eight (8) hours per unit. The Hot Ash from the furnace gets quenched as it enters into the water minimizing the clinker formation The mixture of Ash and Water (SLURRY ) stored in the hopper is discharged through feed gate to clinker grinder to crush the over size clinkers to 25mm and below The crushed clinker along with water, which forms bottom ash slurry is conveyed to Ash Slurry sump Water required for jet pumps is supplied from high pressure (HP) ash water pumps located in Ash water pump house clinker grinder

12. General Process

13. W Shaped System General layout Water Impounded hopper Pic: NTPC-BRBCL Generally water requirement is 3 times that of ash removed The water requirement is reduced greatly in scrapper chain type system ( water:Ash = 10:90)

14. Scrapper Chain Conveying System Belt conveyors are used to dispose the bottom ash from scraper chain conveyor to bottom ash silo. Employ continuously operating or submerged belt conveyor running below boiler furnace. SCC system receives hot clinkers, slag and ash falling from the boiler, through a transition chute to water filled trough. The trough containing the conveyor is filled with water for quenching of bottom ash. Bottom ash is discharged onto scraper chain conveyor, where it is fed to grinder that crushes it to 25mm size. The crushed bottom ash conveyed to bottom ash silo by belt conveyors.

15. General Layout

16. Coarse Ash (Economizer Ash) handling System Coarse Ash from Economizer hoppers is extracted continuously and mixed with water in flushing box provided below each hopper. It is then discharged in to the Ash Slurry Sump. Water required for mixing economizer Ash is provided through separate FAHP Water Pumps. Continuous generated Economizer slurry is fed by gravity into respective bottom ash hopper pipes with necessary slopes

17. Air Pre-heater Ash Handling System Ash generated from APH hopper is evacuated once in a shift by Vacuum conveying system connected with the ESP hopper vacuum conveying system

18. Fly Ash handling system DRY MODE Fly ash carried along with the flue gas from the boiler is collected continuously in ESP hoppers Extraction, transportation and disposal of fly ash from ESP are in two stages

19. In first stage, Ash collected and stored in hoppers is extracted in dry form through pneumatic vacuum extraction system using mechanical exhauster ( vacuum pumps) and taken to buffer hoppers for further transportation to ash silos in next stage In dry transportation system, fly ash from ESP hoppers is taken to buffer hopper located near ESP Ash from the air ash mixture is separated from the air and collected in the primary collector Air is passed through reverse pulse jet type bag filter for further separation of carryover ash Clean air from the outlet of the bag filter is discharged from vacuum pump to atmosphere

20. Ash collected in buffer hopper is transported by Dry pneumatic pressure conveying system to Fly ash Silo Ash collected henceforth in Fly ash silo is then unloaded to bulker for its further use in cement factory Air required for transportation of the ash from Buffer hopper is taken from TRANSPORT AIR COMPRESSOR Fluidizing air blowers are provided to supply hot air for fluidizing the ash in buffer hoppers for effective conveying of the dry fly ash

21. Wet Mode Dry ash is taken to wetting unit, mixed with water and slurry is collected in collector tank The ash slurry is then taken to ash slurry sump to ash pond thru ash slurry disposal pump FAHP water pump provides the high pressure water to wetting unit

22. Pneumatic conveying system of fly ash Pneumatic vacuum conveying system Pneumatic pressure conveying system

23. Pneumatic Vacuum Conveying System Ash is conveyed pneumatically under negative pressure through specially designed valves and pipelines from fly ash hoppers to – Nearby Silo, for eventual disposal in dry or moistened condition Intermediate Surge tank, for onward dry transportation by pneumatic pressure conveying system to remote silo Wetting Unit-Collector Tank – Air washer set, for wet disposal in slurry form The wetting unit system can be a standby for the preceding dry system. The slurry can be mechanical exhausters/vacuum pumps are generally need for creating the vacuum. Hydraulic exhausters, though available,are seldom need nowadays.

24. General Layout

25. Pneumatic pressure conveying system Ash is conveyed pneumatically under positive pressure from Fly ash hoppers or Intermediate surge tank to Silo for dry ash storage. Further, onward disposal is done in dry or semi dry condition through tankers or open trucks

26. Ash Slurry disposal System Bottom Ash slurry, fly Ash slurry and the Coarse Ash slurry shall be pumped from common ash slurry sump upto the dyke area which is located at a distance from slurry pump house.

27. Use Of Fly Ash Ash brick Cement factory Land filling Highway construction THANK YOU