Down Draft Gassifier Wood Burners

Here's the place you can post your favorite wood burning stove and also information on how to build and where to get supplies.
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zelph
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Joined: Tue Aug 14, 2007 1:53 pm

Re: Down Draft Gassifier Wood Burners

Postby zelph » Tue Feb 12, 2008 10:47 pm

DarenN wrote:Zelph;
have you seen this one?
http://intotheborderlands.blogspot.com/ ... sited.html
looks pretty straight-forward.
DarenN.......


While looking over the information and going to the links provided I came onto this site that shows a charcoal product made from cocont shells. Take a look at this site and watch some of the videos. This is interesting stuff. http://www.kingsgrill.com/index.html

Burning a can filled with twigs is difficult to do when the pile is started from the top down. An even start-up of the entire surface is necessary. Starting it with natural tinder found onsite in the woods would be very challenging. The guy talks about starting his with cotton balls smeared with veselene. These types of stove are requiring you bring along a fire starter. If you have to do that, you may as well bring along alcohol for a lightweight alcohol burner and forget the heavy weight wood burner that is call the inverted downdraft gasifier.

My interest in these burners is to study them, try them and come to a conclusion. Are they myth, urban legend or what? Are they practical? Building a small campfire and holding the pot over the fire with an extended green branch supported by a rock pivot would suffice. To what extent do we go? :D
http://www.woodgaz-stove.com/

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DarenN
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Location: Surrey, B.C. Canada

Re: Down Draft Gassifier Wood Burners

Postby DarenN » Tue Feb 12, 2008 11:46 pm

zelph wrote:My interest in these burners is to study them, try them and come to a conclusion. Are they myth, urban legend or what? Are they practical? Building a small campfire and holding the pot over the fire with an extended green branch supported by a rock pivot would suffice. To what extent do we go? :D


my interest is the same as yours. 'does it work?'

i spent almost a year perfecting my MK1 woodburner, but it still blackens pots. that's the part i'd like to get away from. if these 'gasifier' stoves can do that............
the MK1 is an up-draft stove, but it isn't simple. i spent a lot of time and energy getting the venting, and the shape, just right to create a proper draft through the fire. all the while, trying to keep it packable, and make it fit as a potstand without additional parts. i've sold close to fifty of them in less than a year and the only complaint is the black soot on the pot. just like any other fire.
if a gasifier type woodstove could be made to burn as clean as alcohol..........
"I'd rather be happy than right." Slartibartfast

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zelph
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Joined: Tue Aug 14, 2007 1:53 pm

Re: Down Draft Gassifier Wood Burners

Postby zelph » Wed Feb 13, 2008 11:17 am

[quote="DarenNmy interest is the same as yours. 'does it work?'

i spent almost a year perfecting my MK1 woodburner, but it still blackens pots. that's the part i'd like to get away from. if these 'gasifier' stoves can do that............
the MK1 is an up-draft stove, but it isn't simple. i spent a lot of time and energy getting the venting, and the shape, just right to create a proper draft through the fire. all the while, trying to keep it packable, and make it fit as a potstand without additional parts. i've sold close to fifty of them in less than a year and the only complaint is the black soot on the pot. just like any other fire.
if a gasifier type woodstove could be made to burn as clean as alcohol..........[/quote]

I firmly believe that we will never see a packable wood burning stove on the market that is clean burning. I'm talking about wood picked up on the trails etc. not kiln dried exotic woods from home.

The stoves that we see are all updraft stoves. The ones that are lit on top of the twig pile and work it's way down are updraft stoves. The double walled stoves are updraft burners. I believe the double wall doesn't do squat for the performance of the stove.I proved that to myself by doing a comparison between two zip stoves. One was modified to remove the inner wall. They were tested side by side on the same day under the same conditions, same kind of fuel(clothespins) by weight. The modified one out performed the original by a small amount.

The small wood burning stove that I recently tested produced charcoal in the process of burning. Just yesterday I read that to produce charcoal from wood it requires that there be a lack of oxygen so as to cause an incomplete burning of the wood. In order for wood to burn it needs to be gasified(heated to the point of turning to a gas). Your match or butane lighter performs that task when the pile of twigs is ignited. Once the pile is ignited the heat produced starts the chain reaction of turning to gas the twigs next to the flames of the little fire on top of the pile, spreading from one twig to the next. This little stove is a slow burning stove just because it has to burn from the top down. It still produced soot on the bottom of the pot.
http://www.woodgaz-stove.com/

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zelph
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Re: Down Draft Gassifier Wood Burners

Postby zelph » Wed Mar 19, 2008 1:46 pm

I recently read this from a link provided by -------- ?at Whiteblaze.net It gives some insight to how terminology gets in the way when describing a new stove. These Doctors and Professors seem to glorify the stoves they create by the descriptions given of them.

The entire Handbook is a good read for those interested in the subject of wood burners. I pieced together some high points to post here for future reference. Thomas Reed and Paul Anderson have produced commercial stoves.


With “Preface” by Paul S. Anderson:

One relatively new technology
was identified and initiated in 1985 by Dr. Thomas B. Reed. He originally
called it “Inverted DownDraft” (IDD) gasification, but recently we have also
called it “Top-Lit UpDraft” (T-LUD) gasification, a name that more clearly
denotes what is actually happening in this combustion technology. The terms
“gasifier” and “gasification” refer to having any type of combustible gases
from dry biomass created distinctly separate from the combustion of
those gases, even if the separation is only a few millimeters and/or milliseconds.



http://www.crest.org/discussiongroups/r ... sifier.pdf

RICE HUSK
GAS STOVE
HANDBOOK
Alexis T. Belonio
With “Preface” by Paul S. Anderson
APPROPRIATE TECHNOLOGY

PREFACE
The importance of this “Handbook” and the work of Engr. Alexis
Belonio should not be underestimated. I have been given the honor to write
this Preface, and my intent is to illustrate the importance of this work.
The search for technology for clean combustion of low-value dry
biomass in small stoves suitable for residential cooking has been ongoing
for hundreds, if not thousands, of years. One relatively new technology
was identified and initiated in 1985 by Dr. Thomas B. Reed. He originally
called it “Inverted DownDraft” (IDD) gasification, but recently we have also
called it “Top-Lit UpDraft” (T-LUD) gasification, a name that more clearly
denotes what is actually happening in this combustion technology. The terms
“gasifier” and “gasification” refer to having any type of combustible gases
from dry biomass created distinctly separate from the combustion of
those gases, even if the separation is only a few millimeters and/or milliseconds.
Developments and adaptations of Dr. Reed’s IDD or T-LUD
technology during the past twenty years have been slow, mainly without
commercial products, but discussed and shown occasionally as a
combustion curiosity on every inhabited continent.




Juntos T-LUD Gasifier Stoves
The Juntos brand of
Top-Lit Updraft (T-LUD)
gasifier stoves are
developed by Dr. Paul
Anderson of Illinois State
University. Using as fuel
various types of dry
chunky biomass (including
wastes such as yard
wastes, locust tree pods,
and briquettes mainly from
paper pulp and sawdust,
the stove operates by natural convection. Early versions in 2002 were made from tin
can with the top removed and covered with another metal serving
as outer jacket with an annular space of 1 cm to pre-heat the air,
thereby improving the combustion of burning gases. A 2-cm
diameter air pipe is installed at the bottom of the stove reactor to
provide primary air to the burning fuel. (3)
An improved version of this stove, the Juntos Model B,
(shown in Figure 27), has two chambers: (1) the pyrolysis
chamber, and (2) the combustion chamber. The pyrolysis
chamber is the bottom part of the stove that is basically made of a
metal container in which air enters the central fuel area from
underneath a grate that supports the fuel. As reported from the
internet, the pyrolysis chamber has a diameter of 10 cm to 15 cm
and can be made into various heights as long as the flow of
primary air is not obstructed.
The fuel is ignited on top of the
column of fuel, creating smoke
via the process of pyrolysis.
The second chamber is where
the hot flammable pyrolysis
gases receive the flow of
secondary air. The combustion
chamber acts as an internal
chimney so that gases are
completely combusted before
reaching the cooking pot.
The Juntos Model B
T-LUD gasifier (Fig 27) won an
award for cleanest combustion
of nine natural draft biomass
stoves. Simplicity helps keep
its base price below US$10.
T-LUD gasifiers are
batch-fed and can yield
charcoal equaling
approximately 25% by weight of
the load of biomass fuel. (4)
http://www.woodgaz-stove.com/

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zelph
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Re: Down Draft Gassifier Wood Burners

Postby zelph » Wed Mar 19, 2008 10:49 pm

This information highlighted in bold letters is important stuff. These guys are now turning things right side up.

So many have been under the impression that their wood burners were actually drafting downwards.

If you read and re-read these articles you will see how misleading these terms have been. Time to start dispelling the Urban Legend of down draft stoves.

With “Preface” by Paul S. Anderson:

One relatively new technology
was identified and initiated in 1985 by Dr. Thomas B. Reed. He originally
called it “Inverted DownDraft” (IDD) gasification, but recently we have also
called it “Top-Lit UpDraft” (T-LUD) gasification, a name that more clearly
denotes what is actually happening in this combustion technology.
The terms
“gasifier” and “gasification” refer to having any type of combustible gases
from dry biomass created distinctly separate from the combustion of
those gases, even if the separation is only a few millimeters and/or milliseconds.
http://www.woodgaz-stove.com/

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Pure Mahem
Posts: 447
Joined: Fri Sep 21, 2007 4:13 am

Re: Down Draft Gassifier Wood Burners

Postby Pure Mahem » Wed Mar 19, 2008 11:21 pm

I am just now thinking that I may have made a large scale gassifier a few years ago at my seasonal camp site. They give us a tractor trailer rim the kind that splits I placed this on a few old bricks and then placed a Dryer tub on top of it. I used 2 metal rods through the barrel so it would sit down over the tire rim about 4 inches. I put your basic campfire in it and let it go this thing after filling it took off like a jet engine. I had flames about 25 feet in the air. I thought it was great, until a few people came over thinking the camper was on fire. Oh well it was still great but neadless to say the dryertub kind of hit the road. I don't know what just made me think of this now. But I think it may have exploited quiet a few of the gassifier properties.
"Lad I don't know where you've been. But, I see you won first prize!"

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zelph
Posts: 15822
Joined: Tue Aug 14, 2007 1:53 pm

Re: Down Draft Gassifier Wood Burners

Postby zelph » Thu Mar 20, 2008 12:39 pm

Pure Mahem wrote:I am just now thinking that I may have made a large scale gassifier a few years ago at my seasonal camp site. They give us a tractor trailer rim the kind that splits I placed this on a few old bricks and then placed a Dryer tub on top of it. I used 2 metal rods through the barrel so it would sit down over the tire rim about 4 inches. I put your basic campfire in it and let it go this thing after filling it took off like a jet engine. I had flames about 25 feet in the air. I thought it was great, until a few people came over thinking the camper was on fire. Oh well it was still great but neadless to say the dryertub kind of hit the road. I don't know what just made me think of this now. But I think it may have exploited quiet a few of the gassifier properties.


Sounds like my kinda campfire. :D The dryer tub must have looked pretty neat with all the holes showing flame. The entire tub was acting like a chimney, wow!!! I can picture it in my mind, WhoooWheeeee nice one. I'm going to see if I can find one of those dryer tubs. I have a stainless steel tub that came out of a cream separator, about 18" in diameter that works well for a contained backyard firepit.
http://www.woodgaz-stove.com/


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