Swedish fire torch stove - Atcontact.de VideoTube


Swedish fire torch stove 8 years ago

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Here is a stove with strong smokeless flame which also produces charcoal. No fan. Just fill with wood, add a bit of alcohol as fire starter, light a match and throw on top.

Original title: mask stove - make charcoal smokelessly


General principle of TLUD (top lit up draft) stoves: Smouldering wood creates smoke and leaves behind charcoal. Smoke rises and is mixed with fresh air entering the stove above the smoke layer and burned off.

Process details: Air from the small holes allows wood to smoulder continuously but is not enough to maintain a fire after the bit of alcohol is burned off. Rising smoke is mixed with the secondary air from the upper air hole and burned off in a self sustaining flame above the smoke layer. Flame is above and isolated from the charcoal by the smoke to avoid burning the charcoal so as to maximize charcoal production. The fire is smokeless because nearly all the smoke is burned off in the flame. When all water and hydrocarbons have been driven out of the wood the remaining CO production is insufficient to sustain the flame. At this point all of the remaining wood has turned to charcoal. Once the flame is out, remove the top of the stove and sprinkle water on the charcoal to put out the ember. Collect and dry the charcoal for use.

I would love to see someone invent a 45 gallon drum stove to make charcoal which uses pyrolysis and does not burn the wood.

The stove can be used for cooking or heating or boiling water and produce charcoal at the same time. For very dry wood feed, this stove produces about 20% charcoal by weight.

Tools required to make this stove: a can opener, a nail or any pointy tool, a knife and a pair of scissors.
Material: a tall steel beverage can (e.g. coconut juice) and a peach or tomato can.

How to make a mask stove - see description on this first Mask Stove video: http://www.youtube.com/watch?v=_QVhg-wvBp8

Second video of the mask stove shows carbon monoxide reading and the blue flame when fuelled with hard wood pellets: http://www.youtube.com/watch?v=MMTzQKOempQ

Key to the mask stove is the shape of the opening of the two secondary air holes. The size/shape of the cut in the tin evolved from a round hole to a bigger round hole to a round hole with two smaller holes to a rectangular hole to two rectangular holes to the mask stove hole you see here. What I look for is to have the flame in the entire volume of the stove above the secondary air holes. I am satisfied with this version of hole opening shape and believe it is within 85% of the optimal.

How to use a chunk of wood as fuel for the Mask Stove:
- measure a tree branch that will fit in the Mask Stove
- cut a section with length10mm less than the internal height of the stove. Split into 4 pieces using an axe or large knife.
- put two small twigs at the bottom of the stove so that the chunk of wood does not block the primary air holes
- put the tinder (4 pieces of paper towel dosed with methyl alcohol in my case) between the four pieces of wood. Keep the centre of the 4 pieces clear of tinder
- light a match and throw it in

Observations:
- the stove is easy to light and smoke-free when using alcohol-soaked paper as fire starter
- burns very clean and very little visible smoke
- smell of smoke is much stronger than when burning wood pellets
- burned for 33 minutes and left a large pile of hot coal
- spread the charcoal on the snow. After drying, 42g of charcoal was collected.

Earlier result showed this stove takes 90g of wood to boil one litre of water. Note that the best natural draft cook stoves all use less than 50g of wood per litre of water boiled.

Recommendations for future experiments
- try using wood from another type of tree
- try using wood with higher water content matching tropical climates
- try removing the bark to see if the smell can be reduced
- try other plant material
- try cooking something

There are too many small holes at the bottom for burning sticks. Unless the sticks are tightly packed there will be too much primary air. If the speed of the rising air is faster than the burn speed of the smoke/secondary air, it will bellow out smoke that is impossible to keep lit. The easy solution is just make a second stove with less number of holes at the bottom for stick fuel or when simmering is needed. The secondary hole height should be reduced proportionally but the width of the hole should be maintained.

I believe the Mask Stove should work regardless of the size of the can at the bottom. I have a Mask Stove with just a single can which burned a handful of wood pellets to boil 1 litre of water. It produces the same flame characteristic as the video. Only punched 8 holes on the bottom and made the secondary air openings with the same width but shorter in height. It burns for 25 minutes .

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