[Terrapreta] new address to the simple kiln

[folke Günther]

2008/5/27 Ron Larson <rongretlarson at comcast.net>:

>  Folke:
>
>     1.  I like your advance a lot - and suggest it may have
> considerable merit in third world cooking.  You did an excellent job in the
> photos and explanations. Some questions:
>
> a.  What is the weight yield for char in the interior can?   A typical
> number for charcoal-making stoves is 25%.  Yours could be higher as there is
> no "flaming pyrolysis" (less carbon conversion to CO?) in the interior can.
>
*I don't know, but  will measure input -- utput to make a rough estimate *

>  b.  What is the ratio of weights for the exterior combustable wood to the
> interior pyrolyzable wood (before the interior can stops pyrolysis gas
> emissions)?  I.e.  What is the minimum mount of exterior fuel required?
>
*I use to fill up the space between the cans and fire it. Well before the
firewood is burnt out, the pyrolysis starts. Perhaps I take too much just to
be sure.*

> c.  How long did it take before you could see pyrolysis gases coming from
> the interior can?
>
*After the firewood i lit, it taks about 20-25 minutes. It is very much like
making an ordinary fire. After some time, you see that it takes on.*

> d.  How long before the entire pyrolysis operation was completed?
>
*The total time might be about 1 -1.3 hours Then, you have som cooling time
before you can start over again. I use to let it stay to the next day.*

> e.  Have you tried leaves,grasses, and twigs packed tightly in the interior
> can?  These are hard to combust in stoves but still could become valuable
> biochar.
>
*So far I have tried leftover wood from carpentry, bad sunflower seed (
rather smelly because of the high oil content), **Miscanthus **and wood
chips with small twigs among them. I always pack it as thight as I can. I
will go in with pure twigs, but I think it is necessary to dry them
thorough, so they snap when I pack them.*

>  <snip>
> In those early days, we had some discussion of a well-known Indian
> researcher's (name forgotten) efforts to promote an inverse version on
> yours (a central flame within a toroidal outer pyrolysis chamber.  Top
> loaded - major difficulties in sealing.  The design never took off.
>
*I think it is very like Ravi Kumars charcoal producing stove, He calls it
the 'Anila' stove. Attaching a picture. It inspired me a lot, but as I am
lazy of habit, I excluded the internal hole and made the fire on the outside
instead.*

>      c.  The top-lit charcoal-making stove has not taken off as I had
> hoped (in later years, for terra preta/biochar reasons).  There are three
> main reasons I think for that failure.
>         -  One is that a top-lit design is strictly batch operated; your
> design overcomes that because you can add more exterior fuel at any time
> With some modifications in your approach, you could add new fuel at the
> bottom rather than the top.  I suppose that one could find a way to replace
> the interior can - maybe even have the second can move down from an early
> higher position (and itself be replaced by a third can).  It would be nice
> if the lower air supply could be made conrollable (commercial versions maybe
> using a speed-controlled fan??   I found that a ceramic conical "plug" in
> circular holes worked pretty well - compared to sliding "windows".
>
*Yeah. But why complicating it when you can go to the junkyard and get the
parts very cheap? And the feedstock is such as it normaly is in excess.*

>         - The second is that it is messy to shut down, assuming you have
> finished the cooking job with just the right amount of starting fuel
> (reference problem #1)  Lots of smoke when the pyrolysis front gets to the
> bottom -until you open up the lower primary air supply and start consuming
> the char (which we on this list want to save for soil augmentation).  Your
> design solves that problem also (assuming that you only see minimum noxious
> gases at the end??).
>
*No smoke at all. It just stops. *

>         -  The third problem is getting the charcoal out after cooking is
> over.  It is hard ( and messy and somewhat dangerous) to extinguish the hot
> charcoal when you have primary and secondary air ports and a flame exit.
> Your design also solves that problem apparently.  As you note, the interior
> can can have a removable bottom "lid".
>
*Yes, Ihave though of that too, just to make it easy to turn the inner jar
withut loosing the material. But using the outer jar as a 'lid' is good to,
as long as the jar is not larger than your arms are long. *

>
> 3.  This is to urge others to follow Folke's important suggestion about
> being able to cook with this alternative interior-pyrolysis-can design.
>
*A picture of that is added o the page
<http://www.holon.se/folke/carbon/simplechar/simplechar.shtml>now. A more
elaborated page on cookin  a good wok is added later.*

> I spent some months in Ethiopia trying to perfect a charcoal-making design
> (batch type, top-lit, primary (with control) and secondary air supply) for
> the cooking of enjira.  This is a (delicious) thin sourdough flat bread
> cooked on a homemade thick ceramic disk (a "magogo"), of about 60 cm
> diameter.  Has to be one of the most inefficient cooking methods around.  I
> think there is a fair chance that Folke's approach could work there (steel
> (tefloned??) cooking surface being preferred), with this plate maybe sitting
> on top of the interior can.  This might also be applicable (at least
> outdoors) with the la plancha metal cooking surfaces used throughout the
> Spanish-speaking Americas.
>
*I noiced that when putting something flat on the stove, it easily starts
smoking (=incomplete burning of the gasses). Therfore, the wok pan is ideal.
*

> There are probably ways to move this indoors with a chimney.
>     I emphasize that my main justification for further research by this
> list is charcoal production.  But it is also a way of cutting costs
> (assuming future carbon credits) for the roughly 3 billion of the world's
> population cooking at least part of the time with wood.  (Also of course
> increased food production and use of scrap fuels not otherwise combustible
> and headed at least partly towards unwanted methane.)
>
> 4.  I kick myself for having been too top-lighting centric.
> Congratulations to Folke.
>
> Ron
>
>
>
> ----- Original Message -----
>  *From:* folke Günther <folkeg at gmail.com>
> *To:* 'Terra Preta' <terrapreta at bioenergylists.org>
> *Sent:* Monday, May 26, 2008 8:01 PM
> *Subject:* [Terrapreta] new address to the simple kiln
>
>  See http://terrapreta.bioenergylists.org/gunthersimple0508
>
> ---------
>
> A complete description of the simple charring methods for home garden is
> now at http://www.holon.se/folke/carbon/simplechar/simplechar.shtml
> I saw that there is an older address at the terrapreta list. I use it to
> cook the dinner wok at the same time as I am burning the charcoal.
> Sending you a picture of that too asap.
> YS
> FG
>
> --
> NB :Send your mails to folkeg at gmail.com, not to holon.se
> ----------------------------------------
> Folke Günther
> Kollegievägen 19
> 224 73 Lund
> Sweden
> Phone: +46 (0)46 141429
> Cell: +46 (0)709 710306
> URL: http://www.holon.se/folke
> BLOG: http://folkegunther.blogspot.com/
>
> ------------------------------
>
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>


-- 
NB :Send your mails to folkeg at gmail.com, not to holon.se
----------------------------------------
Folke Günther
Kollegievägen 19
224 73 Lund
Sweden
Phone: +46 (0)46 141429
Cell: +46 (0)709 710306
URL: http://www.holon.se/folke
BLOG: http://folkegunther.blogspot.com/
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