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

[CHRISTA ROTH]

Huck, in the GIZ-HERA manual microgasification: https://energypedia.info/wiki/File:Micro_Gasification_2.0_Cooking_with_gas_from_dry_biomass.pdf  you find most of your answers. 
See  pages 12 onwards, where we tried to describe in an easy-enough way step-by-step the processes happening when burning biomass and how the principles are put to work in different stoves/burners. You may find the visualisation helpful, where heat-driven pyrolysis and oxygen-driven char-burning and gas-combustion are separated.  AS Paul Anderson already pointed out, 'TLUD' is not a device but rather an operation mode. 
The figure on page 24 of the manual explains how to switch from TLUD (top-lit up-draft) mode to Bottom-burning  UD mode, if you can deliberately control primary air so you can add sufficient air at the end to burn the char (from whichever side the air gets in bottom and/or side burning).

any stove/burner that provides the option to increase primary air at the end of the char-making pyrolysis process should be able to burn the char. The air control and the configuration of the air-holes matter most: with forced air or substantially increased air flow on the hot char, the char will burn to ash. The configuration of the air-holes will determine, how the char is burnt: wherever an air-hole leads oxygen on the char, you find an increase in the glowing intensity which indicates that the 'char is burnt'.
the TChar concept (8b in the figure) is also explained in more detail on pages 28-30 and again page 60.
Two weeks ago we made an interesting prototype in Madagascar with a simple accessory to an existing charcoal stove. Much easier and cheaper than developing a gasifier from scratch. and a lot safer to use, as you don't need to transfer hot charcoal, you simply lift the accessory up and replace the pot. 
can give you more details if you are interested.
Hope that helps. 
regards
Christa

Am 15.10.2014 um 21:49 schrieb Paul Anderson <psanders at ilstu.edu>:

> Huck,
> 
> In  general, data about the operational aspects and results of use of some stoves (you named two) are not readily available.  You said "seem to burn".   That is different for making direct claims, or of implying that there are no negative effects of burning the char inside the gasifiers.   Some claim to have superior materials, as in the fuel chamber.   You can  ask them directly.
> 
> But unless reasons and differences are clarified and documented, I would agree with the comments by Ray and Julien and Kirk and others, which say:   It is not good practice to burn the charcoal in the TLUD stove that made it.   I thank them all for sending replies, a sure sign that everyone knows that questions to  the Listserv are to everyone, not just to a few who get named in the opening line.
> 
> HOWEVER, there are two exceptions because of differences in the TLUD designs:
> A.   The TChar concept.    See documents at my website and elsewhere.   This has not been implemented (as far as I know) in any particular project with 20 or more stoves, in part because of the difficulty of joining WELL (safety, leaks of primary air, workmanship, variability of charcoal stoves to serve as the bottom base, etc.).
> 
> B.  The charcoal burner insert for the Servals Champion TLUD. See:
> 
> http://www.drtlud.com/2012/09/06/servals-charcoal-burning-attachment-for-champion-tlud-stove/
> 
> I am sure that Sujatha of Servals (a member of this Listserv) will answer specific questions.   None of these inserts is in the USA, as far as I know.   I do not have one.
> 
> Comments on A and B:  The concept is quite appropriate, but both do involve movement, transfer, possible spillage, etc of hot charcoal.    That is similar to the third "option" C.
> 
> C.  Simply pour the hot char into an appropriate stove that is made to burn charcoal, and then continue cooking.    Please note that the char from TLUDs tends to be in smaller pieces than the standard charcoal sold on the streets.   And the existing charcoal stoves are mainly for the street-vendor size charcoal (which is inherently wasteful, but that is not the question being discussed.)
> 
> Huck, because you are initiating a new housing project with kitchens included, you are able to offer to the residents whatever combination of stoves you make available.   We all are anxious to have your results reported back to this Listserv.
> 
> Paul
> 
> Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
> Email:  psanders at ilstu.edu
> Skype: paultlud      Phone: +1-309-452-7072
> Website:  www.drtlud.com
> 
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