[Stoves] Fwd: briqetting charcoal dust and fines with fibers as binders as alternative to starch.

Sat Jun 21 21:30:22 CDT 2014

Dear Richard,
we have designed a rural biogas plant that uses green leaves as feedstock.
It takes about 10 kg green leaves to produce 1 kg biogas. The midribs and
veins of leaves, constituting about 50% of the dry weight of leaves remain
in the digester as non-digested debris, which has to be periodically
removed from the biogas plant by opening a drain valve at the base of the
digester. This debris consists of softened fibres which can be used as a
binder in making briquettes of both charcoal powder as also of sawdust.
Yours
A.D.Karve

On Sun, Jun 22, 2014 at 5:48 AM, Richard Stanley <rstanley at legacyfound.org>
wrote:

>   Dear Jeff and Rolf and  AD,
>
> For  all who are considering the use of starch as the main binding agent
> for char and charcoal based briquette blends,  I would offer an
> alternative: The use of  natural plant fibers as naturally occurring
> agricultural residues. These grasses straws fronds stringy stem materials
> can make great binders If you know how to soften them such that they deform
> plastically while still retuning fiber tensile strength. We cover this ad
> nauseam in our User Producer Manual available thru our website but its not
> all that complicated  in its basic form.
> We do this because a) starch in itself f does not burn well and b) Starch
> requires boiling at least heating water to make the paste. The waste plant
> material is combustible, and it only requires chopping and semi
> decomposition in natural sunny conditions, but thats about it.
> I just sent this out to a more recent briquetter, Eric Theiss. Thought it
> might assist you all in what we are learning about how to densify and
> rigidify  briquettes without need for more force or starch binder.
>
> (At least when it comes to infilling granular materials in the blend, size
> matters !
>
> Richard Stanley
> www.legacyfound.org,
> Ashland Oregon,
>
> =========
>
> Begin forwarded message:
>
> *From: *Richard Stanley <rstanley at legacyfound.org>
> *Date: *June 10, 2014 1:57:54 PM PDT
> *To: *Eric T <2etpdq at gmail.com>
> *Subject: **Fwd: briq. sample comments *
>
>
> HI Eric,
> Well I did a few tests on your samples and discovered that while your mix
> is very fibrous the fibers are far too plentiful to really benefit from
> just compaction in and do of themselves What you had been adding was too
> coarse to fill int the gaps that existed too. i added fine sawdust then
> crumbles charcoal in varying quantities and found that if I selected the
> finer stuff (falls thru a door screen) it does a great job of densifying
> the material…(I used our standard compound lever press which was generating
> at max 1000 kgs over a 10 cm dia. cylinder face. Minus the 1 1/8th's inch
> dia. hole in the center. That= a net surface cross sectional area of ~75 cm
> ^2 or a pressure per unit area of 1000/75=13 kgs per cm ^ or roughly about
> 190 psi.
>
> Adding more force does not increase the density. In-filling with the right
> size of material does. (By the way I am using soupy slurry of probably 50%
> water or more--to assure full dissociation and distribution of the fines
> and fibers within the feedstock)..(I am also measuring on basis of unit
> weight per dry volume of samples)
>
> the compressed donuts (bottommost photos) are drying as well speak but
> even a day old the difference between them in terms of felt density is
> remarkable. the charcoal fines sample below easily doubles the density of
> the raw sample and is about 1.5x the fine sawdust additive blend.
>
> Some other observations:
> I pushed the charcoal additive to the point of fiber binding failure  per
> below. ( you sample on left for control, 25% sawdust added, then 50% (Next,
> --no sample shown here--  adding more sawdust than that failed the test;
> ie., not enough fibers to hold the mass together.
>
> Next with charcoal fines first ( sample not shown here) I tested crude
> crumbled charcoal that would fall only through ¼" square wire mesh it was
> not densifying much at all despite about 50% added force in the press--
> Then ( shown below second from right) I added further pulverised charcoal
> that would fall through a door screen ≈ ⅛" mesh size. Per sample --second
> from right-- I added 40% then pushed it on up to 60% ( that sample not
> shown here but represented in the donut briquette below) with good binding
>  and excellent  infilling. When I pushed it on up to ≈75% fine charcoal I
> saw the failure as shown on the right sample below.
>
>
> close ups show gradations of infilling ;
>
> below:
> (your raw sample unaltered composition, reformed and squeezed in my hand)
>
>
>
> Below: same raw sample blended with 25% added blend of medium to fine
> sawdust equal mix of residues off chop saw and belt sander..
>
>
>
>
> Below: pushed sawdust to 50% but while it was still binding up well it was
> still not densifying as much as it could.
>
>
>
>
> below; charcoal fines as infiller ≤40%
>
>
>
>
> Below; charcoal fines ≥70% = insufficient fiber binder and structural
> failure
>
>
>
>
> compressed briquettes below
>
> 1) ( on left);  your original material reformatted into the donut shape
> per description above:
> 2) (center) your raw sample blended with 40% charcoal fines (⅛" dia minus
> --down to powder-- sieve size)
> 3) (right) 60% charcoal fInes same sieve size )
>
> Other characteristics as additional indicators:
> • The rate of compaction (amount of movement of piston to buildup of
> resistance / pressure) decreases to right.
> • There is a  noted reduction in the rate of expansion just after molding
>  to the right.
> • The amount of slurried feedstock added to the cylinder pre-compression,
> was about equal in the samples below.
>
> In short:
> Your feedstock is too fibrous (you are going to too much work processing
> using these precious fibers, when you could instead be using far less of
> them with far more really fine additives. Note course "sawdust or charcoal
> crumbs larger than the ⅛" minus size will not add much at all. ). For the
>   biggest bang for your buck,  get ahold of really fine 1/8" minus sieve
> size combustible material. The best for heat output is charcoal but any
> wood or oily based combustible husk material would come in a close second
> creating moor of a wood fire....
>
> These same samples were then dried over four days in ambient conditions
> and measured. the starting sample of  ≈sg 0.23,  to  40% charcoal fines at
> sg 0.30,  to 60% charcoal fines (amour maximum before structural failure
> (due to an insufficient fiber binding content), with an sg of 0.42
>
> hasta,
> Richard Stanley
>
>
>
>
>
>
>
>
>
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>
>
>
>
> Sent from my iPhone
>
>
> Sent from my iPhone
>
>
>
>
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>

-- 
***
Dr. A.D. Karve
Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)
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