[Terrapreta] Folke's retort kiln

[bakaryjatta]

Dear list members,

It is with great regret I see nice simple things being discussed until 
people get headaches (and more confused) All I see is that a retort without 
a tight lid is put upside down in a larger drum which is used to contain 
fuel surrounding the retort. There is no air entering the retort and no fire 
inside, but if the contents are heated, volatile gasses escape at the 
bottom. These gasses meet with the external fire and air entering through 
the holes at the base of the larger drum. Once the fuel is lit and the 
temperature of the stock to be charred is high enough to produce gas, no 
further fuel is required to keep the process going. You may light the fuel 
between the retort and the outer drum at the top and possibly also through 
the air holes at the bottom of the outer drum. Refuelling can only been done 
from the top until gas from the retort starts to escape to take over the 
firing.

Very nice and handy for small batches. And usable for cooking using a wok. 
As Gunther explained, a flat cooking surface would block the draft.

My 200 l drum retort is too big for cooking. Really, I would like to find 
out how to control the process and store the extra gas for other purposes.

Someone told me once not to complicate subjects when talking to simple 
folks. KISS, KISS ( Keep It Simple Stupid)

We have no choice in audience on internet, but if we want to influence large 
numbers to become of active participants in applying TP for its many 
benefits, perhaps the experts should try hard to introduce KISS KISS 
technology and use KISS KISS communication. And a drum equals a bag of rice 
in cost here. That's a big investment when many earn less than that per 
month.

Kind regards,

Bakary Jatta


Francoise Precy <f.precy at hotmail.co.uk wrote:
>
>
> Hi everyone,
>
> http://www.holon.se/folke/carbon/simplechar/simplechar.shtml
> Trying to piece things together and clear up my understanding. What got 
> said so far:
>
> On 27 May 2008 22:51:33 -0700 "Philip Small" wrote:
> ?when the pyrolysis front advances "upwind", against the draft, and that 
> draft comes from below, it corresponds to the same principles as both top 
> lit updraft pyrolysis and reverse downdraft pyrolysis. The draft carries 
> smoke, generated between the pyrolysis front and the charcoal, across the 
> hot char to the flame.? This device is top-lit so we ?get some of this 
> effect.? ?The more he controls his Superficial Velocity (Source - PDF 
> http://www.woodgas.com/Superficial%20Velocity.pdf), the more benefit he 
> can get from this effect.? ?Only a toplit "stage 1" is a candidate (for 
> that effect).
> ?after the initial batch burns down, (...) the retort is still putting out 
> woodgas?. When the fuel (is topped up), (the pyrolizing) does ?not conform 
> to the same effect.?  ?Superficial Velocity effects (affects?) the 
> pyrolysis gas temp as it closes in on the charcoal. ie slower SV cracks 
> more CO2, until it's too slow to keep the flame above the charcoal burning 
> red hot enough to radiate down (so as) to push the pyrolysis front 
> (advancing upwind, away from the charcoal). OK my head hurts now. -philip
>
> This gets me confused b/c I imagine the draft going down (towards the only 
> way out, so there is a downdraft inside that inner barrel), and the 
> flame(s) being mostly up albeit outside. Assuming that the pyrolysis 
> starts within at the top, is the pyrolysis front on top of the layer of 
> charcoal or underneath it?
> If it's underneath, then the gases get 'filtered' mostly by the biomass / 
> wood etc, not by the charcoal. If the pyrolysis front is on top, which 
> doesn't make much sense to me so far, then the gases get filtered both by 
> charcoal and by biomass. Was seeing it underneath but Philip ain't the 
> only one who gets a headache from it, so by now I just can't work out 
> anything further
> The only sort of sensible thing I can think of is a system of 3 barrels of 
> progressive sizes, the smallest (with a few small vents at the bottom 
> maybe) filled with wood / biomass, sitting upstraight inside the largest; 
> with the intermediary barrel turned over (bottom up) coming on top of the 
> smallest barrel. So the smoke would have to go through the charcoal, come 
> out by the top, go down the inner side of the intermediate barrel, and get 
> burnt on the outside of it.
> One notable advantage as far as I am concerned: saves lugging full barrels 
> about (can't see myself lifting ? not dragging ? on my own 2 metal bins 
> with the smaller one full of wood). So allows for bigger batches than a 
> poxy 20 litres-sized one. Don't know about any advantage re. elimination 
> of gases.
> Serious potential downfall: it'll probably take longer to heat up as the 
> fire is not in direct contact with the container that holds the wood. 
> Wonder if anyone's got any more precise idea on that point?
>
> ?Wok pan?:
> 2008/5/27 Ron Larson wrote: ?enjira. This is a (delicious) thin sourdough 
> flat bread cooked on a homemade thick ceramic disk (a "magogo"), of about 
> 60 cm diameter.... this plate (disc) maybe sitting on top of the interior 
> can (barrel).?
> Folke answers: ?when putting something flat on the stove, it easily starts 
> smoking (=incomplete burning of the gasses).? So it's not the 
> wok-pan-shape that's necessarily needed: if the 'plate / disc' is sitting 
> on top of the inner barrel without overlapping (too much) the gap between 
> the inner and outer barrel, the combustion of gases should still be 
> effective. May also raise the disc on 3 stones so it leaves a gap between 
> itself and the outer barrel's rim.
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