[Stoves] material processing for briquettes few tips on technique

[Richard Stanley]

Andrew, likewise for your own posts:
 
I am taking the liberty of  sending it out thru the briquetting network, to our colleagues in Guatemala and to a high school science teacher and long friend of the family who, as ex Guatemala peace corpsman,  accompanied us on our  trip in June, to the field sites.  This was his own insight: And as it began to evolve, up ther in the little town of Sacapulas,  the director of our counterpart organisation, detailed its use in practice. Voila ! We began to realise potential throughout the corn using Maya culture. The interesting thing is that agricultural  lime is available almost everywhere. Its use in this form, for briquete producers,  has a pretty huge implication, globally.  

We will need the fibers intact: Reducing the lignin thru "white rot" to free them up without dissolving them, would be the real objective. 
This like so many other aspects of briquetting would make a great Msc or PhD dissertation: Any takers ?  we can give you ample field site support !

Will keep you posted, Andrew.

On Roks hole size to height discussion
Its of course his own call based on his own solid and well vetted testing experience. 
Many prefer longer, log shaped briquettes but as I recall from sage Tom Reed,  the effective draft is dimishes as  chimney height to diameter increases. He noted ratios of 5 to one for hsi metal chimneys. It sSeems to have a parallel  in hydraulics too. For any given "roughness coefficient" of pipe material, so much "head loss" is experienced with a given length of pipe. I have found that the chimney height  (in this case the hollow core briquette acting in part, as its chimney) should not exceed about 4 diameters (Three is about optimum--for optimum air flow, although   the cooking appliance and type –and duration– of heat desired, as well as the kind of blend being used,  all come to play somewhat). Bqs of the 16 cm variety of about 100 cm height typically had 50 mm holes to my own experience ( see the early video on our website). 

  Similarly Kobus Venter and John Davies worked with coal blends and concluded that a cross notching of the base would accomplish much of the same thing--the essential distribution of air from inside to  circumference. Rok subsequently went further into the issue a few years ago with Approvecho's help, to work out air flow issues around the circumference as well. His concusion like Crispins more recent discovery as part of a project in the Gambia,  Crispin's own conclusion was that a stack of several shorter bqs favors airflow from inside to outside of briquette as well, something far less possible with one solid log shape. How the flame migrates thru the burn, has  also been studied intensively by your own fellow citisen (and fellow of the briquette realm), in Nottingham, Joel Chaney in partial fufillment of his PhD dissertation in Mechanical Engieering, a year or so back.

But meanwhile, back out in Miumbuni, Kenya ….There is this remarkable intuitive 'knowledge unspake' that we have the priveledge of accessing as well.
So much to do, so little time eh !
 
Thanks much again for this contribution, Andrew. I will tyrot keep you abrest of any new developments in this arena.

Kind regards and pressing on, 

Richard Stanley
www.legacyfound.org
 


On Aug 4, 2012, at 10:04 AM, ajheggie at gmail.com wrote:

On Fri, 3 Aug 2012 10:32:14 -0700, Richard Stanley wrote:

> If processed correctly,  natural fibers will flex and then tend to interlock once blended with other materials in a water slurry.  
> One does not  achieve this by simple chopping or even direct use of the fiber without some form of softening (thru partial decompsition, in a hot humid anerobic environment,  (under such as a black plastic bag), or as we are learning from our Mayan colleagues in Guatemala,  use of agricultural lime (which is traditionally discarded after its use in hot water to soften and de-shell their corn kernals).

As always I find your posts on briquetting educational.

Alkalis, lime being calcium hydroxide, dissolve lignin and I expect
this is what the bugs do in retting fibres out of the stem
(simplistically wood rotting fungi can be classified into brown, white
and soft rots, the white rots attack lignin and leave the cellulose,
brown eat the cellulose and soft rots invade all the cells), it's
lignin that hold all the stringy fibres together. So I can see how
lime would separate out the fibres.

Your observation that the bugs work better in anaerobic conditions
may be that this is what favours a white rot. Flax sheaves where laid
in a water filled ditch to ret.

I may have missed something in Rok's post: Rok mentions 16cms diameter
briquettes with a 5 cms hole, I take it it is the length he is varying
between 3-12 cms and favouring a length of between 5 and 7cms?

AJH


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