[Stoves] Charcoal burning in stoves (was Re: LPG import in India

neiltm at uwclub.net neiltm at uwclub.net
Sat Dec 30 06:22:48 CST 2017


On 29 Dec 2017 at 9:52, Paul Anderson wrote:

> Neil,
> 
> On 12/28/2017 4:54 PM, neiltm at uwclub.net wrote:
> > With very fine char such as the TLUDs produce, I re-use the mesh
> > scavenged from other peoples discarded disposable BBQ trays doubled up
> > across the grate to retain the fines.  Lit with a couple of sheets of
> > newspaper, and an old computer fan to augment the draft, we are cooking
> > in under a minute of striking the match.
> I understand the grate and the char placement.   What are the walls like 
> in this charcoal burner?
> 
> What is the thickness of the char layer (because some air needs to be 
> able to pass upward through the char, riight?
> 

Yes. I've never measured, which would be difficult given very varied 
sized pieces of char, but little more than is needed to cover the grate 
generously, so say an inch/ inch and a half, with larger pieces poking up 
above that.  My reason for coming up with the fan in the first place was 
experiencing too much ND draft restriction with the fine char, but mostly 
it is needed only for quick starting, adding fuel, and occasionally as a 
boost, more so if I am starting with a thicker layer, and sometimes to 
get the last gasp out of an exhausting layer more quickly.

> Is the ignition paper under the grate?
> 

Yes, that's right.  There is a small sliding door to regulate the draft 
which I made a sheet metal 'funnel' to (push) fit, with the computer fan 
at the other end, running off any old 12v car battery.  This ensures a 
rapid and complete combustion of the paper, and immediate and even 
ignition of the char.  For about 30 seconds the billowing white smoke 
looks as if I'm announcing the election of a new Pope before all rapidly 
settles down to a smokeless burn.

> How long wiill it burn (in relation to thickness of layer?   or to 
> weight?   or what else?)
> 

I've not done any weight measurements, but I find it hard to imagine a 
more fuel efficient BBQ.

I usually start with enough fuel for a half hour cook before needing to 
add more fuel.  Because it is only a fairly small BBQ, (14inch diameter 
griddle), I usually cook in batches, adding more char each time.  If I'm 
cooking chicken joints from raw I aim for about 40 minutes which is easy 
to achieve on one loading. There seems little point in trying to control 
a thicker layer for a longer time than the food needs to cook, so each 
batch of food gets its own fresh layer of fuel.

This is all made easier by the excellent control I have over the fire, 
whether by entirely regulating the ND with the sliding 'door', or if 
needed, occasionally bringing the fire up with the fan, usually only in 
short bursts or for getting the flames to quickly break through a new 
layer of char.  In addition to these options, there are 4 heights at 
which the grill can be held above the fire.  Mostly I aim not to have 
flames licking around the food, and if things get too lively are brought 
back under control quickly by closing the draft off.  The heat is greater 
at the centre and towards the back, so food is also moved around as 
required.

> Any other comments that might be useful???
> 

The fine char in the mix definitely helps with rapid lighting and 
establishment of a cooking fire compared with large lumpwood only.  

> The issue is "combustion of charcoal that is NOT lump and is somewhat 
> "fine" but not powder(?).
> 

Correct.  I use a fine riddle to remove the ash and char below the mesh 
size which is approx 2.5mm sq hole size.  Obviously most of the char is 
well above that sort of size, being the sort of mix you would expect from 
a TLUD, rocket stove or open fire.  It's only the open fire char where I 
ever need to break up some of the larger lumps.

I can do some measurements and photos when the warmer weather comes if it 
might be of any interest.  I've had this BBQ for 25 years now, so its a 
familiar tool that I am nicely attuned to, and the design persists, 
although as I said I couldn't find it on ebay.com, only .co.uk.

Best wishes,   Neil Taylor

> Paul
> 
> Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
> Email:  psanders at ilstu.edu
> Skype:   paultlud    Phone: +1-309-452-7072
> Website:  www.drtlud.com
> 
> 
> 
> 
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