[Stoves] Traditonal Charcola Making Process / retort

[Tom Miles]

Crispin,

That looks like a goal worth exploring further. 

To maintain 1250 C (2282 F) you would definitely need dry wood and a
gasifier. A TLUD probably burns at too high excess air, i.e. heats up too
much nitrogen, to maintain the high temperature.

I'm still unclear as to what size kiln (m3 and kW) makes sense from a batch
curing perspective. How many stoves per batch and what size kiln do you
need?

Tom

  

> -----Original Message-----
> From: stoves-bounces at listserv.repp.org [mailto:stoves-
> bounces at listserv.repp.org] On Behalf Of Crispin Pemberton-Pigott
> Sent: Tuesday, July 03, 2007 8:13 AM
> To: 'Discussion of biomass cooking stoves'
> Subject: Re: [Stoves] Traditonal Charcola Making Process / retort
> 
> Dear Paul
> 
> I was not going to consider a kiln type until I learned more about the
> type
> of gases produced, the heat content in them, problems I might face
> running
> it for a long time and the economic of the firing and the charcoal.
> 
> Energy is quite expensive at $0.14 per KWH in Maputo - if you are using
> electricity.  I don't yet know the cost of wood when bought in bulk.
> Charcoal is $12 for 70 Kg retail, roughly 2000 MJ = 544 KWH or $0.02 a
> KWH.
> 
> Wood is probably 1/2 the price or less (remember that transport is
> expensive).
> 
> Turning wood into charcoal is a big business so diverting wood to make
> woodgas and charcoal would be more efficient than traditional methods
> (which
> yield about 15%).  The problem is the charcoal is not worth much so it
> might
> be better simply to use wood to fire the kiln, but I like the idea of
> turning out a large amount of charcoal if I can.  It has a huge market.
> It
> will displace inefficiently produced competition.
> 
> If I get 0.75 Kg of charcoal per stove fired and I produce 500 stoves a
> day
> at each of 10 locations, I get 3.75 tons of charcoal a day.  That will
> take
> 14 tons of wood a day.  While this sounds like a lot, it is a pittance
> compared with what is going on in the rural areas now to provide 300
> tons a
> day.
> 
> If I can buy 14 tons of wood and make 5000 stoves, and still turn out
> $640
> worth of charcoal, as well as save 3.5 x 5000 KWH in electricity =
> $2450.
> Saving $2450 and generating $640 leave a lot of money to buy 14 tons of
> wood.  In fact I could afford to pay more than $0.20 a kg which is more
> than
> the charcoal costs retail!
> 
> This means that it is very attractive to use biomass to fire the
> stoves.
> Now...check this out!  Each stove put into the market saves about 60%
> of the
> charcoal which means that to save the energy in biomass that was used
> to
> create it will take only about a day.  To save the purchaser the price
> of
> the stove takes about 3 weeks.  That is a pretty good deal all round.
> 
> It also means that promoting the use of biomass to fire modern charcoal
> stoves is environmentally defensible from every point of view.
> 
> The main question is what temperature I can get the kiln to, and
> maintain,
> using a gasifier.  This affects the chemistry chosen for the mixture.
> If I
> can maintain 1250, a full 80 degrees higher than I am using now, I can
> use
> less feldspar, lower the cost and still get a low thermal expansion
> product
> - probably even get a lower expansion value.
> 
> So that is my reasoning and present view.
> 
> Thanks
> Crispin
> 
> 
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