Re: Gasifier fundamental question

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

Dear Paul, Crispin and All:

If you light the stove at the bottom and then pour on the fuel, in the first
2-3 minutes ALL the volatiles are driven off, much faster than you can
supply secondary combustion air to burn them cleanly.

If you light the stove at the TOP, the pyrolysis front moves downward in a
very regular manner, releasing the fuel at a constant rate (10 g/hr = 3 kW
for our stoves on high).

See attached graphs of our latest campstove attached, with efficiencies of
38-45%, and graph of water temp, weight of fuel remaining...

(Why are we discussing what we can so easily try?)

Yours truly,            TOM REED
----- Original Message -----
From: "Paul S. Anderson" <psanders@ilstu.edu>
To: "New Dawn Engineering" <admin@newdawn.sz>
Cc: "Ron Larson" <ronallarson@qwest.net>; <tombreed@attbi.com>; "Apolinário
J Malawene" <ajmalawene01@hotmail.com>; "Bob and Karla Weldon"
<bobkarlaweldon@cs.com>; "Ed Francis" <cfranc@ilstu.edu>; "Tsamba--Alberto
Julio" <ajtsamba@zebra.uem.mz>; "Lily Coyle" <astrozen2000@hotmail.com>;
<stoves@crest.org>
Sent: Thursday, April 11, 2002 11:51 AM
Subject: Gasifier fundamental question


> 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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Campstove - 8cm.xls

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