[ethos] RE: [Stoves] Charcoal Stoves (Thomas Reed)

[Dean Still]

Dear Kevin,

The "tall insulated chimney" that Tom refers to was 33cm tall made from
light weight fire brick material. The charcoal was placed at the bottom of
this cylinder on a grate which allowed room air to pass up through the
burning charcoal. We'll make a video of it this week.

Best,

Dean

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Kevin Chisholm
Sent: Sunday, June 18, 2006 7:20 PM
To: tmiles at trmiles.com; 'stoves list'
Cc: ethos at vrac.iastate.edu
Subject: Re: RE: [ethos] RE: [Stoves] Charcoal Stoves (Thomas Reed)

Dear Tom and Dean
----- Original Message ----- 
From: "Tom Miles" <tmiles at trmiles.com>
To: <tmiles at trmiles.com>; "'stoves list'" <stoves at listserv.repp.org>
Cc: <ethos at vrac.iastate.edu>
Sent: Sunday, June 18, 2006 11:45 PM
Subject: RE: RE: [ethos] RE: [Stoves] Charcoal Stoves (Thomas Reed)


...del...>
> Either way it looks like the techniques Dean has used to reduce CO (tall
> insulated chimney - might improve CO and efficiency for a wide range of
> charcoal qualities.
>
There is a lot of good to be said for chimneys:
1: They vent the products of combustion outside the living space, and 
virtually eliminatre concerns for Indoor Air Quality.
2: The draft they create allows the Strove Designer to get much better 
control over primary and secondary air, to give combustion which is much 
more complete.
3: They permit the efficient use of a wider range of fuel conditions, for 
example, smaller size, and higher moisture content.

Up with Chimneys!! :-)

Best wishes,

Kevin

> Tom
>
>
> -----Original Message-----
> From: stoves-bounces at listserv.repp.org
> [mailto:stoves-bounces at listserv.repp.org] On Behalf Of John Hofmeyr
> Sent: Sunday, June 18, 2006 4:52 PM
> To: stoves list
> Subject: Re: RE: [ethos] RE: [Stoves] Charcoal Stoves (Thomas Reed)
>
> Hi Tom and others,
>
> In Message-ID: < <mailto:44948947.5070903 at comcast.net>
> 44948947.5070903 at comcast.net> Tom Reed wrote: 'The question of
> "combustability" and efficiency is very complex.  Conventional charcoal 
> made
> for cooking represents a "buffered endpoint" in charcoal making.'
>
>
>
> Questions were raised about the CV and volatiles content of charcoal with
> respect to its efficiency in cooking. I wonder whether the fixed carbon
> content is maybe a more important consideration, because this is the value
> which will translate into the utilisable energy, especially for grilling,
> simmering and stewing.
>
> I introduce this idea, because, while the energy in the volatiles is
> important for ignition, I think this energy is likely to be burnt off
> rapidly?
>
> Therefore, would this energy only be useful, for example, to bring a pot 
> to
> the boil?
>
> If yes, would the energy from the glowing charcoal be recoverable more
> efficiently and over a longer period?
>
> And would this energy be maximised if the Fixed Carbon content of the
> charcoal is maximised, but with balanced volatiles for ignition (about
> 12-15%%, dry basis)?
>
>
>
> I think it is for this reason that the EU specifications for charcoal tend
> to require a fixed carbon content above 80%, to ensure smokeless burning 
> and
> to avoid rapid burn-off  of volatiles.
>
>
>
> Further, on  Sent: Monday, June 05, 2006 3:35 PM Dean wrote: "2/3rds of 
> the
> energy in wood is lost when making it into charcoal."
>
>
>
> Properly-carbonised wood returns ~70% of its CV as solid, in the form of
> biocharcoal with Fixed Carbon >80%.
>
> By this I mean for example:
>
> 12000 tpa wood at 25% moisture equivalent to 9000 tpa bone dry at 
> 19GJ/ton,
> yields 4000 tpa biocharcoal (80%FC) at 30GJ/ton.
>
>
>
> Regards,    John in Joburg
>
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