Re: Gasifier fundamental question

["Tom Reed" <tombreed@attbi.com>]

Dear All:

I agree with Karve that it makes a LOT of difference where the charcoal is
burned.  In our WoodGas CampStove the volatiles burn at the top of the
gasifier with secondary air, producing a flame like propane and high heat.

When the volatiles are completely burned, the combustion/gasification of the
charcoal is near the bottom of the gasifier, 10 cm from the pot and so much
of the radiation heat is disipated.

However, if we INCREASE the air to the charcoal, it is gasified to CO in
sufficient quantity to produce a beautiful CO flame at the secondary air
holes.

The air fuel ratio for volatiles in a dry fuel is about 1.  For charcoal it
is 6!

TOM REED          BEF GASWORKS
----- Original Message -----
From: "A.D. Karve" <adkarve@pn2.vsnl.net.in>
To: <stoves@crest.org>
Cc: "Paul S. Anderson" <psanders@ilstu.edu>
Sent: Saturday, April 13, 2002 7:03 PM
Subject: Re: Gasifier fundamental question


> Paul asked what difference it made if the gas burnt in the upper part of
the
> stove and the charcoal on the grate.  According to him, heat was heat, and
> as long as all the fuel was burnt, and all the heat released, it should
not
> make any difference, whether the heat came from the gas or from the
> charcoal.  I feel that the location of combustion has an effect on
> transfering the heat to the pot.  The charcoal burning on the grate is at
> least six inches from the pot and therefore it may not trasfer all its
heat
> to the pot, whereas the gas burning just below the pot may trasnfer
> relatively more heat to the pot. That is why it makes sense if the
volatile
> part of wood and the charcoal are burnt in two separate stoves, each
> designed to burn a specific fuel.
> A.D.Karve
> -----Original Message-----
> From: Paul S. Anderson <psanders@ilstu.edu>
> To: Crispin <crispin@newdawn.sz>; Stoves <stoves@crest.org>
> Cc: Bob and Karla Weldon <bobkarlaweldon@cs.com>; Ed Francis
> <cfranc@ilstu.edu>; Tsamba--Alberto Julio <ajtsamba@zebra.uem.mz>; Lily
> Coyle <astrozen2000@hotmail.com>
> Date: Sunday, April 14, 2002 3:21 AM
> Subject: Re: Gasifier fundamental question
>
>
> >Stovers,
> >
> >Crispin wrote, and I emphasize:::::::
> >
> >>Many thanks for all the energy contributors spend adding fuel to this
> fire!
> >
> >And that includes Crispin messages, too.
> >
> >Short Notes from Paul:
> >
> >1.  Ron correctly notes that MY terminology (such as use of "burning"
when
> >I should say "pyrolysis") leaves much to be desired.  But Ron responded
so
> >well that now Crispin has been able to respond with some clear statements
> >that raise questions.
> >
> >2.  When properly functioning (which was not the case with my stoves on
> >Crispin's patio), the Juntos stove does NOT give noticeable "smoke" (that
I
> >think of as "visible particles"), but there are certainly some issues of
> >unseen gasses, as with all stoves.  When the Juntos gasifier unit has
> >sufficient chimney of a couple of inches, the gasification goes to the
end
> >without smoke, with the result being only glowing charcoal.  Problems
arise
> >when some of the fuel has fallen through the grate and therefore
continues
> >to give gasses (smoke) when the charcoal is removed.
> >
> >3.  A stove that is lighted, functioning, and hot is a different beast
from
> >a cool-start stove.  Therefore, adding in fuel on top of a hot charcoal
bed
> >WITH EXTREME CONTROL OF THE PRIMARY AIR  entering under the charcoal
COULD
> >(in my humble opinion) have pyrolysis gasification down low where the
> >charcoal is in contact with the new fuel and then also have the secondary
> >combustion of the gases a few inches above the top of the fuel load.  But
> >issues of fuel types (including different moisture content of the same
> >fuel) could become more important than when those fuels were in the
> >top-lighted gasification configuration.(?)
> >
> >Please keep the comments coming, and feel free to separate out the
diverse
> >topics into separate threads of messages.
> >
> >I am learning, and I hope others are also.
> >
> >Paul
> >
> >
> >
> >
> >
> >Paul S. Anderson, Ph.D.,  Fulbright Prof. to Mozambique 8/99 - 7/00
> >Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003
> >Dept of Geography - Geology (Box 4400), Illinois State University
> >Normal, IL  61790-4400   Voice:  309-438-7360;  FAX:  309-438-5310
> >E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders
> >
> >
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http://www.crest.org/articles/static/1/1011975339_7.html Gasification
http://www.crest.org/articles/static/1/1011975672_7.html Carbon
>
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