Donut Wood Stove - Simple Blue Flame Wood Gas Stove

Last update: 2010-11-06
Donut-shaped stove which burns with a short blue strong flame. Boils 1 litre of water from 23C in 12 minutes. 54 minutes burn on one can of wood.

This video shows the the first prototype. For the latest version click here: http://www.youtube.com/watch?v=czoEp9xD7GY

WARNING: Smells smoky. Light smoke with pot of water on it. Carbon monoxide reading of 112ppm when burning and 177ppm when flame is out, which is deadly if used inside a small tent. Always use under a fume hood which exhausts air outside the house or use it outdoors.

-height 120mm, dia 98mm. 20 4mm holes
-donut hole dia 40mm, height 90mm. IMPORTANT: fill pellets up to 10mm below hole.
-290g hard wood pellets
-add one layer of charred pellets before adding fuel to prevent small smoke puffs when pyrolysis reaches holes.
Note: my preferred method to light pellets now is to add a bit of methyl alcohol to some expanded wood pellets and then light. Expanded pellets are made by placing some a few sheets of wet newspaper on top of a layer of pellets and then wait for the newspaper and pellets to dry. Store the expanded pellets in a jar until needed.
- Burn time: 54 minutes
- Pot stand for 10mm gap

IMPORTANT : Either put the stove on a grate or design a grate and hole at the bottom of the stove for air.

- I tried cooking with this several more times, sometimes it is very blue and other times less so. For this video, I believe the wax used as fire starter and my use of the Apple Nano to record this contributes to the blueness. Further observation based on cooking on a larger version of this stove seems to indicate that amount of wood pellets used is another factor.
- soot left on the pot
- use taller side wall for outdoor as wind shield. If too short, wind will blow out one part of the flame/charcoal will smoke at that part/flame will continue to burn on the other parts
- When pyrolysis reaches bottom layer, flame becomes stronger for 3 minutes then weakens. Flame then continues in one part of the fuel. Other parts may smoke.
- When finish cooking, dump pellets/charcoal in a container of water
- If donut hole is too big or if pellets loaded too high, it will be difficult to light and will take longer to boil water.

Recommendations for further experiments:
- Seems to work better with a convex lens shaped disk / gas wick, Also tried a funnel shaped cap with fins which sits directly on the edge of the air tube to shape the flow of gas/air
- Add an outer can for downdraft pre-heated air
- Insulate outside can
- Punch (not drill) a ring of 4mm holes half way between donut hole exist and rim
- Shape the donut hole to have a wider bottom (might help to reduce the flame size near the end of the burn).

References for top-lit-up-draft wood gas stoves:
Paul S. Anderson, Ph.D.Dr. TLUD (Tee-lud), TLUD Handbook, http://www.bioenergylists.org/files/TLUD%20Handbook%202010-02-21.pdf
http://www.hedon.info/docs/BP53-Anderson-14.pdf

Inspiration for this design comes from:
Tom Reed
Ronal Larson
Paul Anderson
Crispin Pemberton-Pigott
Paal Wendelbo
Ray Garlington
Nathaniel Mulcahy (WorldStove)
Zen Seeker (ZenStoves)
UnlimitedBushcraft
MrBillTroop73
TerraFirma369
guns4toys
NCHiker1970
WorldStove
lannyplans
hiramcook
minibulldesign
trailgear555
jasonklass
and many others.

Category:

Science & Technology

Tags:

• Donut
• Wood
• Gas
• Stove
• pellets
• charcoal
• room
• space
• heater
• Make
• TLUD
• emergency
• survival
• camping
• biomass
• biochar
• cooking
• hiking
• backpack
• hobo
• gasifier
• education
• scouts
• axial
• tube

[joakim2407]

Have you ever tried using wood chips instead of pellets? I'm curious to see if it would work. =)

[jw934]

@joakim2407 I have not. But now that you mentioned it, I'll try it. I can get some chips from the flower bed or cut a stick into small chunks or just go buy a bag of hickory BBQ flavouring wood chips. Perhaps I'll cut up a stick as that is most likely what I would use in an emergency or for camping. I'll try it this weekend and post the video. Thanks for the suggestion. By the way, I'll use my new blue flame stove (/watch?v=lOrc5Ua3weQ) instead of the donut wood stove.

[jw934]

@joakim2407 If the wood chip is even very slightly damp, the stove does not work at all. Once the accelerant runs out the flame only lasts 2 minute. But after I dry the wood chips on top of a barbecue, the peanut magic stove works great. Got about 20 minutes burn with about just 8 pencil sized sticks. I guess if I was out camping somewhere other than in a desert, I would always carry some dry wood sticks or chips. I would use it to both cook and dry some more sticks afterwards.

[joakim2407]

@jw934 I've tried using wood chips from a fairly dry pine. I used my home made wood gasifier stove, based on the one BCoutdoorsurvival makes; see the related videos list. My first attempt was not that good, it burned quite bright for 5 minutes, but didn't really gasify properly. I then cut the chips into thinner pieces, about 3-4 millimeters in width, filled it up and lit it using some fine shavings on the top. It worked really well, had about a 15 min clean burn and almost no remaining coals =)

[jw934]

@joakim2407 I just checked out that video. Thanks for the suggestion. Even though it hasn't rained here for two days, I am still having trouble finding wood lying on the ground that is dry enough. I saw a patent for a stove for use in sub-zero conditions. It had three walls to maximize heat retention and pre-heats both primary and secondary air. Perhaps I will get around to build one of those one day.

[jw934]

I finally figure out how to light a Donut Wood Stove and keep it burning reliably in the wind. The problem was that whenever there is wind, it is hard to light. If the fuel to one side of the tube blows out the flame on the other side would not be able to light it. This causes a large amount of smoke.

The solution consists of:

- redesign the stove with higher sides

- add a wind screen/pot skirt outside of the stove and pot

- light the stove by dumping a layer of burning pellets on top

[joakim2407]

@jw934 I'd love to see you try that out =)

Back to my stove; I've found that it works all right even with wood that's not completely dry. I used fine shavings in between pencil sized wood chips, all which I got from the inner wood of a dead standing pine, as it had rained the night before. I find pine and birch to be the best fuel for my stove, but every kind of three will do as long as it's dry enough.

Now that winter is coming, I'd love to see you experiment with a "sub-zero stove" =)

[jw934]

@Jigaboo123456 See my new method for starting gasification in the description for the Hammer Stove. It may solve the problem you described.

[jw934]

@jw934 Video on Hammer Stove posted.

[jw934]

I have stopped experimenting with the Donut Wood Stove. Tried different configurations, but could not achieve the rate of success required. The problem is that even with slight wind, only one section of the fuel would burn and the other part of the stove just produces smoke.

Just started to develop a "hammer stove" that so far seems to solve that problem. I will do some camping with it and try it many more times before posting a video. Minutes to build using two pop cans and reusable.