[Stoves] Why doesn't charcoal burn in the Champion TLUD?

Wed Oct 15 14:45:40 CDT 2014

Bernhard, Huck,

The Vietnam Magic Flame Stove is a TLUD stove that burns torrefied biomass
pellets.
It use a fan to supply the air needed for gasification.

http://www.bioenergylists.org/files/A%20Clean%20Burning%20Cookstove%20-%20Belonio%20etal%202010.pdf

https://www.youtube.com/watch?v=5juuitxuWVU

They have solved the problem of burning torrefied biomass pellets with a
secondary flame (near the pot).

I think that is possible to burn charcoal pellets with a flame at the
secondary air level after the end of the pirolysis stage, in the same TLUD.
It can be done using a fan to provide sufficient air for gasification of
the charcoal pellets, or with a sufficient tall chimney (with primary air
full open).

For example, i achieve this with a burner with secondary air holes located
on top of the concentrator ring.
With this burner, is more easy to burn the gases than a "standard" TLUD
burner.

This is a video of one of my TLUD (the first version of the burner):

https://www.youtube.com/watch?v=uq-5nq8Rx08

The material stress, i think, was resolved in the oorja stove, with a very
thick cast iron grate.

With this possibility, the user or cooker can have the decision to burn all
the fuel pellets, or to save the char or biochar for later use.

Greetings
Roberto Poehlmann

*Bernhard Müller* bs_mueller at gmx.net
<stoves%40lists.bioenergylists.org?Subject=Re%3A%20%5BStoves%5D%20%20Why%20doesn%27t%20charcoal%20burn%20in%20the%20Champion%20TLUD%3F&In-Reply-To=%3CCE6423BB-9FFE-42C0-8BE2-F421E5584DF8%40gmx.net%3E>
*Tue Oct 14 23:54:39 MDT 2014*

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------------------------------

Huck,
once there is enough primary air, the charcoal does burn in a TLUD,
but it should be avoided for several reasons:
1. the distance between the embers and the pot is too long to obtain a
sufficient heat transfer
2. the material (steel) would be stressed too much
3. the extremely toxic CO will not be turned into CO2 completely. This
is an important factor since TLUDs are operated mostly indoors in
developing countries.
Bernhard S. Mueller
Eschborn, Germany

Am 14.10.2014 um 20:00 schrieb stoves-request at
lists.bioenergylists.org
<http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>:

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*> > >* Today's Topics:
*> >*   1. Why doesn't charcoal burn in the Champion TLUD? (Huck Rorick)
*>*   2. Why doesn't charcoal burn in the Champion TLUD? (Julien Winter)
*> > >* ----------------------------------------------------------------------
*> >* Message: 1
*>* Date: Tue, 14 Oct 2014 09:36:35 -0700
*>* From: "Huck Rorick" <huckrorick at groundwork.org
<http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>>
*>* To: <psanders at ilstu.edu
<http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>>,	<stoves
at lists.bioenergylists.org
<http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>>
*>* Subject: [Stoves] Why doesn't charcoal burn in the Champion TLUD?
*>* Message-ID: <009201cfe7cd$11cf6470$356e2d50$@groundwork.org
<http://groundwork.org>>
*>* Content-Type: text/plain; charset="us-ascii"
*> >* Hi Paul,
*> > > >* Can you explain why the charcoal in a Champion TLUD doesn't
burn?  There is
*>* heat generated to drive off the gases from the wood.  Why doesn't that heat
*>* burn the carbon as well?
*> > > >* Under what circumstances would it burn?
*> > > >* If you leave the charcoal in the bottom of the TLUD and
don't dump it out
*>* into an airtight container will it slowly burn away in the bottom of the
*>* TLUD?  If you shut off the primary air?  Will it burn away quickly if you
*>* give maximum primary air?
*> > > >* Huck
*> >* Huck Rorick
*> >* Executive Director
*>* Groundwork Institute
*>* 2640 Silvercrest Street
*>* Pinole, CA 94564
*>* Phone: 510-222-4111
*>* email:  <mailto:huckrorick at groundwork.org
<http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>>
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www.groundwork.org <http://www.groundwork.org>
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*> >* ------------------------------
*> >* Message: 2
*>* Date: Tue, 14 Oct 2014 13:36:03 -0400
*>* From: Julien Winter <winter.julien at gmail.com
<http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>>
*>* To: Discussion of biomass cooking stoves
*>* 	<stoves at lists.bioenergylists.org
<http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>>
*>* Subject: [Stoves] Why doesn't charcoal burn in the Champion TLUD?
*>* Message-ID:
*>* 	<CALv4xTyzrQ5MMwAfLnLoSChgAytjp+J-E_iQ6QeGNmF+EATK+Q at
mail.gmail.com <http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>>
*>* Content-Type: text/plain; charset="utf-8"
*> >* Dear Huck;
*> >* Charcoal from pellets burn slowly in a Champion-type TLUD,
because there is
*>* not enough primary air movement.  The resistance to gas movement in the
*>* charcoal bed is too high.  Also, there isn't the draft from a strong
*>* pyrogas flame.
*> >* If you burn wood chips or sticks, the gas permeability of the char bed is
*>* high, and the charcoal will burn off quite well.
*> >* It would be nice, however, if one can get the charcoal fire closer to the
*>* bottom of the pot so that there is better transmission of radiant heat.
*>* Paul has a TLUD for that which breaks in half when the pyrolysis phase is
*>* complete.  Otherwise the path between the char fire and the pot should be
*>* well insulated.
*> >* Some people mention how good it is to have a fan to force the primary air.
*>* That is true for pellets, but not so much for sticks and chips, because
*>* their permeability is already high and their bulk density is low (so you
*>* will burn off your batch of fuel is 10 minutes if you force the air).
*> >* (I should note that the gas permeability of a bed of fine wood chips (< 10
*>* mm)  is also low).
*> >* I keep promising data to show this.  Its coming soon.
*> >* Cheers,
*>* Julien.
*> >* --
*>* Julien Winter
*>* Cobourg, ON, CANADA
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