[Stoves] Char from coir Re: Biochar Inquiry

Musungu Wycliffe Nabutola reecon at mitsuminet.com
Wed Apr 16 02:56:55 CDT 2014


Dear Stovers,

The production of briquettes from coconut husk needs a binder. We did look
at the possibility of using starch, from Tapioca (cassava), that was even
more expensive. We ended up using clay. In Mombasa the clay is also not
cheap and very difficult to come by.

Musungu

 

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Crispin Pembert-Pigott
Sent: 15 April 2014 17:23
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] Char from coir Re: Biochar Inquiry

 

Preaching to the Coir

 

It may be work mentioning (maybe not) that I gave burning coir a shot in
2003 using the only materials available - which required bringing coconut
husks from Mozambique as Swaziland only has one palm tree.

 

What I found was that the 'particle size' was pretty important at any fixed
scale. This means that the number of chunks in the combustion chamber is
sort of fixed, and that means about 4 pieces across the diameter to get a
burn at all, and probably my universal number of <6 is better to get a
reliable burn.

 

Observations at the time are that the outer husk is the major source of
energy driving the burn, and that there is a lot of gas produced which burns
well provided several things are 'on track'.

 

The environment has to be hot (not open) and there is a clear two-stage burn
taking place. This means it is inherently a char-making fire even if it is
bottom lit. This, Paul, may impact your interpretation of what is possible.

 

The outer hard bit burns pretty well though with a lot of long chain
particle smoke, and the soft bits which are often pretty damp smoulder
driven by the fire from the outer husk.  The result is that the softer
fibrous inner husk is pyrolysed and creates wood gas, with a clearly defined
secondary burn taking place above the fuel (provided of course there is
secondary air available and it is contained etc etc).

 

Why this happens is clearly because there are two different fuels burning:
the inner and outer husk. 

 

The conclusion I drew was that coconut husk can be burned very cleanly, that
char can be produced without making it a TLUD, and that it has to be large
in diameter compared with a small cooking stove.  Applications would be for
schools and prison cooking, dormitories and perhaps large scale water
heating. 

 

It is likely to be suited to a hopper-fed crossdraft burner with char taken
out from the 'far side' at the appropriate time.

 

Because there is a huge amount of work required to make pellets from coir or
to chop up the husks into small pieces, I suggest that the best use of this
is for something 'industrial' such as process heat.

 

If one wanted a reliance char product (for briquetting) then it should be
done in matches and the smoke burned for process heat like salt making, and
the charcoal sold as a cooking fuel.

 

Regards

Crispin

 

 

 

From: Paul Anderson <mailto:psanders at ilstu.edu>  

Sent: Tuesday, April 15, 2014 6:33 AM

To: lhelferty at biochar.ca ; teddy <mailto:teddykinyanjui at hotmail.com>
kinyanjui 

Cc: biochar at yahoogroups.com ; Ted <mailto:tswysocki at hotmail.com>  Wysocki ;
Johnathon Caguiat <mailto:johnathon.caguiat at mail.utoronto.ca>  ; Discussion
of biomass cooking stoves <mailto:stoves at lists.bioenergylists.org>  

Subject: [Stoves] Char from coir Re: Biochar Inquiry

 

Stovers and Biochar folks,

Our thanks to Teddy in Kenya for his comments below sent to Lloyd H. and a
few others, and especially for the link to his blogspot (well worth seeing).
It shows that he has successful creation of char from coir (coconut husk).
But do note that his kiln is ignited at the bottom, and then has the coir
put on top.   That clearly seems to work, and I see that as mainly a
"retort" style of pyrolysis, with the heat (and no oxygen) rising from the
bottom to pyrolyze the coir.   So, if you are only trying to make char (or
biochar) from coir, consider Teddy's method.   Maybe Trevor can replicate
this in the Marshall Islands, or others do it wherever possible.
Considering the tons and tons of coir around for free, and the need for
biochar for soil improvement in the "coconut-belt" of the world, this could
be quite significant.

Clearly it is not TLUD processing, so the question still remains if TLUD
pyrolytic methods and temperatures can sustain the secondary flame for
cooking and yield char.

Paul

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