RE: History of very small true gasifier units

["Ron Larson" <ronallarson@qwest.net>]

Paul ( cc Andrew and stoves)

You said:

1.  "I have become interested in the history of the development of very
small
true gasifier combustion units.

But I question every claim for "gasifiers" because the definitions are so
weak.  For example, I give below the recent messages from Crispin and AJH.

	<snip some material from Crispin and AJH for clarity - you saying:>

My comment and question:  Just because it is top-lit does not make it a
gasifier.  There would need to be air intentionally entering at the bottom,
to come up through the biomass (straw), and create gases specifically to be
flared later (milli-seconds or longer) when secondary air is intentionally
introduced.

I suspect that the "can with straw" did NOT have air entering at the
bottom, but because the straw is so much like loose paper, the air from the
top that could reach the burning zone was providing sufficient primary air
AND simultaneously providing the secondary air needed to get the flame.

Anyone with further (and first hand) information about the "can with straw"
combustion unit, please send it to me (via Stoves List is best so that all
can comment.)  (I am sending this also to the "Gasification List Serve" for
comments from that perspective.)"

(RWL1):  I too would like to hear more from anyone in Kampala or
knowledgeable on such a fuel.  But I also hope some others on the list can
try this experiment.  I can't agree with your postulate - as I think it
would never be able to burn cleanly in that manner.  I'll bet that the
experiment also needs to have a sizeable (15-20 cm?) height for a 10-12 cm
fuel diameter as a  "chimney- combustion space" above the top level of straw
and secondary air inlets. My main point is that I see no reason straw as
described should  not work in the right design.  It is wonderful to hear
that someone is burning straw cleanly and that it is the cheapest fuel
around. Alex English is the person on our list with the largest history of
"charcoaling" straw.  Alex?

2.  You also said:

"Meanwhile, I would like to hear from anyone about OTHER very small
gasifiers, including when where who what etc.  I am sure that some of you
experimented with the likes of Tom Reed's IDD gasifier.  I will post my
1-page "Short introduction to the Juntos Gasifier Stove" very soon,
probably today, without pictures so it will transmit easily.

	(RWL):  I look forward to your short history.  I spent a lot of time 7-8
years ago trying to find earlier examples of charcoal-making stoves - mostly
unsuccessfully.  Many of the first responses when we were still part of
"bioenergy" was that it couldn't be done.  Then Tom Duke - a very bright
Iowa farmer reported on doing something similar with two holes in the
ground - getting separate control of both primary and secondary air.  He
said that he had heard of this with the term "Mormon" stove.  He said he
tried  it (I never have) and was able to make it work.

	I have looked at piles of remote traditional charcoal-making literature and
have never found a description with top lighting and bottom air entry - with
or without flaring (which would need secondary air of course).  But some of
the Swedish literature from several centuries ago had some of the feel for
this approach.  They had some charcoaling designs where they had their first
lighting right in the center of big piles.  No flaring, ever, I believe -
but they did seem to have a uniformly moving outward (and some downward)
movement or the pyrolysis front - opposite to the direction of the air flow.
Most rural charcoal making that I have read about does bottom lighting.

	About six months after I first started writing about my experiments on
"bioenergy" and then "stoves" - I had a message from a Swedish PhD student
who was doing a follow-up thesis on a different (maybe even a Professor on
sabbatical) stove researcher who sounded as though he had introduced
something very much like what I had developed - maybe even in Uganda.   I
have lost the computer on which that message sat - and I don't believe this
doctoral student was ever active on "stoves" or reported his work to us.   I
spent some time today trying to locate Swedish doctoral stoves theses -
unsuccessfully.  I don't believe I ever saw a picture of the stove - but
seem to recall that it sounded like it had natural draft with top lighting
and at least primary air control.  I hope any Scandinavian listening in with
access to stove theses or stove (maybe missionary) African development might
be able to identify this.  I might remember the name.  The thesis work
should have been started in about 1994 or 1995

	Best I can do on your question - sorry.

3.  And you concluded:
"Also, I refer to my previous posting of 3 days ago about "Theory and
terminology questions about combustion".  Not a single comment from anyone
yet."

(RWL3)  I will comment on this as a response to a later message of today,
which includes Andrew and then Tom Reed.


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