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Ash Handling System

What is Ash?

  • Ash is the residue remaining after the coal is incinerated.

Composition of ash handling system?

  • SiO2, Al2O3, Fe2O3, CaO , MgO.

Why Ash Handling System is required?

  • In Thermal Power Plant’s coal is generally used as fuel and hence the ash is produced as the byproduct of Combustion. Ash generated in power plant is about 30-40% of total coal consumption and hence the system is required to handle Ash for its proper utilization or disposal.

Ash terminology in power plants?

  • Fly Ash ( Around 80% is the value of fly ash generated)
  • Bottom ash (Bottom ash is 20% of the ash generated in coal based power stations.

What is fly ash?

  • Ash generated in the ESP which got carried out with the flue gas is generally called Fly ash. It also consists of Air pre heater ash & Economiser ash (it is about 2 % of the total ash content).

What is bottom ash?

  • Ash generated below furnace of the steam generator is called the bottom ash.


Volume of ash and properties



System Description

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. Description is as follows:


  1. A.      Bottom Ash Handling System

Bottom ash resulting from the combustion of coal in the boiler shall fall into the over ground, refractory lined, water impounded, maintained level, double V-Section type/ W type steel- fabricated bottom ash hopper having a hold up volume to store bottom ash and economizer ash of maximum allowable condition with the rate specified. The slurry formed shall be transported to slurry sump through pipes.

  1. B.      Coarse Ash (Economizer Ash) handling System

Ash generated in Economizer hoppers shall be evacuated continuously through flushing boxes. Continuous generated Economizer slurry shall be fed by gravity into respective bottom ash hopper pipes with necessary slope.

  1. C.      Air Pre Heater ash handling system

Ash generated from APH hoppers shall be evacuated once in a shift by vacuum conveying system connected with the ESP hopper vacuum conveying system.


  1. D.      Fly Ash Handling System

Fly ash is considered to be collected in ESP Hoppers. Fly ash from ESP hoppers extracted by Vacuum Pumps up to Intermediate Surge Hopper cum Bag Filter for further Dry Conveying to fly ash silo.

Under each surge hopper ash vessels shall be connected with Oil free screw compressor for conveying the fly ash from Intermediate Surge Hopper to silo. Total fly ash generated from each unit will be conveyed through streams operating simultaneously and in parallel.

  1. E.       Ash Slurry Disposal System


Bottom Ash slurry, Fly ash slurry and the Coarse Ash slurry shall be pumped from the common ash slurry sump up to the dyke area which is located at a distance from Slurry pump house.

Related Pages

  1. khmitesh permalink

    What is the typical area required for Ash Pond for any 660X2 MW Thermal Power plant ?

    • Narender Rakhra permalink

      As per NTPC specifictaion about 11 acres of land is required for 3 X 660MW with coal having 40 % of Ash Content

      • Sathishwaran.G permalink

        i want the over all calculation parts of ash handling plant…capacity of hopper,like that…

  2. United Conveyor Corporation has earned a reputation for providing quality service and great products to their customers in every aspect of a project. They offer great customer service and provide various ash handling systems to help your plants performance.

  3. dave permalink

    great technology

  4. bhaskar permalink

    can you tell me the implications of lowering down the water level to avoid splashing of water due to falling of ash on boiler tubes. how feasible it would be?

    • The design of Boiler is such that it can not splash the water on Boiler tube. LOwering of water level is not permitted as basic function of water is to maintain the pressure in the furnace. If the pressure increases beyond the limit then due to higher pressure inside the fire will come out of the joints and leakages. Boiler furnace is under negative pressure everytime.

  5. can u tell me wat is gap timing in conveyer . nd how it is mesured nd calculated

  6. shubham jain permalink

    i want to know about more detail about the foundation of terbine generator raft

  7. amitkumar permalink

    sir,i am amit can u suggestion sir what is advantage ash handling system .and what type used ash .

  8. super informatio

    • khmitesh permalink

      Hello Kori Putnanja,

      Thanks for the compliment for our wordpress blog, we will appreciate if you can throw more questions; so we can make a complete “Q&A – thermal power plant blog”. Which will intend help young engineers ?
      Thanks again, for the complement; this will help to keep our enthu up.

  9. Thank you for this basic and valuable information…!

  10. sammy permalink

    what is the working of intermediate surge hopper? It has openings for both coarse ash for ash slurry & fine ash for fly ash silo….how it is achieved in ISH??

  11. Good explanation industryal ash handilng system

  12. amit singh permalink

    good idea for knolewge…….

    • amit singh permalink

      what is a D pump in ash handling.

      • khmitesh permalink

        No Idea, what a D pump is. Will try to find it.

      • ukganjir permalink

        D pump is ash conveying device, which transfer ash to main plant to silos.

  13. Shovan Ray permalink

    good for us

  14. priyo hutomo permalink

    i want to know impeler type on sump pump.please tell bro

    • khmitesh permalink

      Will definitely put it in the next article.

  15. Thank you for another excellent article. The place else
    could anybody get that type of info in such a perfect manner of writing?
    I’ve a presentation next week, and I am at the look for such information.

  16. gp saravanan permalink

    i want more than que?

  17. Rahul Biswas permalink

    can any body tell me what is dense phase ash conveying system in short??

  18. Where will I get the layout of ash handling plant or its block diagram

  19. yatin permalink

    what is use of ash silo ?

  20. subrahmanyam goriparthi permalink

    Sir, I need yo known what are types of bottom ash handling system other than water impounded system… Latest techniques in fly ash handling system.

  21. i interested Ash handling bt may i one question all of you plz -sory I talk hindi kya koi bachpan se pwoer plant ke bare me sikh ke ata hai !!!! My experience balco 540mw o&m ahp area not a balco employee !!!

    • khmitesh permalink

      you can share your thought in Hindi too….all ideas are welcome in this forum

  22. mahesh permalink

    d pumps are also ash handling system that is normally seen in cement plants. these systems fitted below the fly ash silo which directly convey the ash to cement plant. Normally the conveying time is 20 minutes or above.

  23. Altaf hussain permalink

    All posses are god so, im good knowledge

  24. muthussamy permalink

    is there any project in ash disposal techniques

  25. Pradeep Nyathari permalink

    good basic information of industrial ash handling system

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