Gasifier fundamental question

["Paul S. Anderson" <psanders@ilstu.edu>]

Stovers (especially Tom and Ron)

Crispin at New Dawn Engineering wrote to me:
>Dear Paul
...  (snip)
>I wanted to see what people came
>up with as a reason for burning from the top down.  I am singularly
>unimpressed with the reasoning.  I suspect that it is a 'given' not to be
>questioned.  I am still waiting to hear ANY reasonable explanation for not
>smoking off the wood in any pattern or position.  Charcoal is made by
>running the smoke (from the charing process) through the uncharred wood.
>Why should it be different with a stove??
.....

VERY sound statements.  Now, what do the experts say?

I can imagine that the issues of "fire present" versus "heat without fire, 
as in a retort" could be very important, especially for issues of control 
of the amount of gases being generated.

I think we have a requirement of burning the gases soon after generation 
because we are dealing with SMALL stoves and POOR economic 
conditions.   And that also might influence what is and is not possible 
with top lighting versus bottom lighting.

IMPORTANT NOTE:    It is not really "top" vs "bottom" because SOME 
gasifiers force the air downward through the fuel, making it the equivalent 
of bottom lighting where the air flow is upward.     Instead, the issue 
focuses on the air flow going AGAINST the direction of the pyrolysis 
front.   Tom Reed called his stove the IDD  (Inverted DownDraft gasifier) 
and many people do not like that expression, because it is really an 
UpDraft,  BUT it is directed AGAINST the progression of the burning that 
comes downward from the top

Therefore, when the draft and the progression of the burning are in the 
SAME direction, IS there control of the gasification process (as separate 
from the "burning" of the char after (or simultaneously with) the gases 
having been driven off?

What this boils down to is this:  How are the "against burn" draft and the 
"with burn" draft crucial with the gasification process as envisioned for 
the small-scale domestic household stoves such as the Juntos stoves or the 
Reed-Larson IDD stoves or even the Reed "Turbo" stoves with blowers?

Looking forward to the replies.   Tom R, please forward this to the 
Gasification List serve if those people should see it, but request that 
replies get sent to the Stoves List serve.

Paul






>Re you call for assistance:
>
>1.  Emissions testing.  Must be scientific and rigorous, with appropriate
>quantification according to the variables of fuels and combustion
>chambers.  You need to have the equipment and knowhow.  We provide the
>stove(s) and info about the fuels.
>
>I put the question the Executive of REASWA today and they were interested to
>do the testing here at the Cemistry Department of the Kwaluseni campus.  It
>is a real possibility that the equipment could be bought by the project and
>used only for our purposes, and if others want to have things tested the
>project would get income from its use (like R1000 per test?).
>
>2.  Efficiency testing:  Very similar to the above statement, but this is
>more closely linked to the issues of combustion chambers and the stove
>structures (placement of the pots to get higher efficiency).
>
>Ditto.  No reason not to build capacity in the local university.  It will
>certainly be cheaper that the USA and we can do a lot more of it.
>
>We (REASWA) have a project that requires testing inside houses as well as
>stoves so these things seem to fit together with great synchronicity.
>
>3.  External examiners:  We will seek an independent review periodically
>during the 3 years  of the Shell grant.
>
>Seems we have located someone already.
>
>I liked the grid of options and relationships for examining the stove
>components.
>
>I have thought about implementation and schools that prepare a lot of food
>for lunch feeding schemes are ripe for testing purposes as they are many and
>malleable.  They also use a great deal of fuel collected by students.  We
>can get 'professional' opinions from the cooks too.
>
>I am likely to go ahead with the solar stove project with GTZ and this fits
>well with the manufacturing capacities that are required.  I will get three
>samples from them in the next few days.
>
>I haven't lit a match since you were here as I am tooooo busy but money is
>at last rolling slowly.  The pumps for Moz are under way at last - 100 of
>them.
>
>Nothing else at the moment.  Glad to hear you are up and running again.
>
>Regards
>Crispin

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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