Temperature of ash

Posted in: , on 24. May. 2007 - 18:53

Dear sirs,

Please let me know what is the temperature of coal ash below bunker discharge, and is it possible to use submerged belt conveyor there.

Thanking you,



Re: Temperature Of Ash

Posted on 24. May. 2007 - 05:19

I've seen it red hot before it hits the quench water.

Submerged belts have been used, though I think more normally submerged chain conveyors are used.

Depends a bit on the amount of as the conveyor needs to take away.

Re: Temperature Of Ash

Posted on 25. May. 2007 - 05:14

I have seen mostly very heavy drags in this application, sometimes submerged screws in smaller applications.

Never seen a belt used for this. It is a brutal application for a belt particularly because you can never make a perfect skirt seal around the belt edges and material will quickly grout the belt in solid. Under water you will not know what is happening until everything stops.

Re: Temperature Of Ash

Posted on 25. May. 2007 - 06:15

Thank you Mr. J D < designer,

I have alo seen said drag conveyor but in my current enquiry my client is using Baggase, Husk, coal fuel it depends on availability of fuel, I have already supplied such conveyors for husk, and bagasse, I just wanted to know whether it is possible to use belt, coz when ash drops in the conveyor it passes through the water means the temperature of the ash will defienatly drop and we can use hr grade belt which will able to stand up to 150-160 c and the capacity of the conveyor is also low as 5.0 tonns / hr.

by the way thank you for your reply


Re: Temperature Of Ash

Posted on 25. May. 2007 - 08:56

For Bagasse/Coal fired boilers submerged belt conveyors are the norm.

Check the type of coal, the ash content and if possible the type of ash produced. This could vary from very fine grits to large clinkers depending upon the coal being burnt.

Regarding temperature..... This is a variable since the grits lose temperature very quickly whilst the clinkers take much longer. Hence check the coal type and also check if the type of boiler proposed is prone to developing clinkers.

Engicon specialises in correcting non-performing plants and low cost de-bottlenecking of systems.

Re: Temperature Of Ash

Posted on 26. May. 2007 - 05:36

Dave, I am curious how the belt is installed in the quench tank so that fines don't get around the edges and build up below the carrying belt.

Also, are these belts or chain belts? (ie a belt bolted to a heavy chain on each edge so that it can pass through a tight concave curve)

Lyle Brown
(not verified)

Re: Temperature Of Ash

Posted on 26. May. 2007 - 11:51

In Australia where a number of our power stations run on glorified dirt and the boilers have questionable clinker control, the boiler ash handling equipment is more akin to that used in a mining environment (longwall AFC’s etc).

See RUD as an example:


This company has various ranges (systems) also, dedicated to boiler ash handling:


Though I think their concepts are based on steel belting of some configuration.

In the applications I am referring to a belt (fabric or steel cord) conveyor wouldn’t last a day.

As for temperature, it depends, how are you going to cool it - much water to ash do you have, what is the temperature of the ash and water (are you going to cool it? or supplement it with cool feed water to maintain the temperature etc)? You could do a calc using heat transfer and some assumptions.



Re: Temperature Of Ash

Posted on 29. May. 2007 - 05:59


Have used both the SSC (Submerged Scraper Conveyor), and the underwater conventional troughed belt conveyor, for bottom ash.

What I learnt from this is that the SSC is far superior, especially if designed by someone who has done it before (many times.....many, many many times).

I hope this helps you


LSL Tekpro

Graham Spriggs

Re: Temperature Of Ash

Posted on 30. May. 2007 - 08:14

At 5 tph you could dump it into a skip full of water. Depends on how far you want to go. Five tph is perilousy small to justify forking out cash on an SSCC.

Belting must be a joke.

John Gateley johngateley@hotmail.com www.the-credible-bulk.com

Re: Temperature Of Ash

Posted on 30. May. 2007 - 08:18

Good point John

I missed the fact that it is only 5t/h

For this duty we normally sluice the ash to a pit and simply pump it away.


LSL Tekpro

Graham Spriggs

Re: Temperature Of Ash

Posted on 30. May. 2007 - 08:46

Oh, and incidentally...

There are about eight coal fired dryers at a Phosphate plant here in RSA at Phalaborwa.

Each produces a small amount of ash which is water quenched and sluiced to pits.

From there it is removed from the wet pits by a slow spiral clasifiers (screw conveyors).

The capacity is so low that once a day, a front end loader clears the ash piles.

Be careful with the interface between the fire grate and the sluice.

On this particular installation the design was prone to occasional blockages, and I lost a very good friend Jhonnie Stukkie, who was burned to death trying to unblock dryer number 6 fire box from below, which was the only access point.

LSL Tekpro

Graham Spriggs

Re: Temperature Of Ash

Posted on 30. May. 2007 - 10:00

For 5 T/hr you can use a small industrial scale submerged ash conveyor rather than the large versions you see at the back of power stations. There are lots about.