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

[Kevin Chisholm]

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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