Gasification Wood Stoves

[Kieran]

What is the difference between a gasification stove & a normal stove like the honey stove? :/

[MikeWilkinson]

For all you need to know about various wood stoves go here:-

http://zenstoves.net/Wood.htm

And for some ideas on DIYing a non-powered one see here :-
http://www.bioenergylists.org/files/EverythingNice_Stove_Instructions.pdf

[Ashley Cawley]

What is the difference between a gasification stove & a normal stove like the honey stove? :/
In my own words; Gasification stoves make better use of the gases that burn from Wood. Normally only some of the expelled gas is burnt in an open fire, but with a gasification stove more (or all) of the gas expelled is burnt, making it more efficient (your getting more heat-energy out of the wood your burning).

When you see a gasification stoves working properly, you will be able to tell something different is going on by watching the flames, someone might post a photo or video to show it..

[Kieran]

In my own words; Gasification stoves make better use of the gases that burn from Wood. Normally only some of the expelled gas is burnt in an open fire, but with a gasification stove more (or all) of the gas expelled is burnt, making it more efficient (your getting more heat-energy out of the wood your burning).

When you see a gasification stoves working properly, you will be able to tell something different is going on by watching the flames, someone might post a photo or video to show it..
thanks ash

[MikeWilkinson]

This has got to be one of my favourite wood gassifiers, when he gets it going check the flame out - Blue!!!


http://www.youtube.com/watch?v=6XxL6pPGGCE"]http://www.youtube.com/watch?v=6XxL6pPGGCE

And this one is slightly different - you can tell when it starts burning wood gas as the flames start at the vents and not on the woodpile.


http://www.youtube.com/watch?v=6Dc9w7FzmuU

[paul standley]

Here's my 10 pennies worth...

As a general rule, Wood gasification stoves usually rely on burning a single load of fuel (wood, cones, pellets etc) and once the fire is going, you wouldn't add more fuel to it.

Also, they tend to be lit from the top (kindling at the top on top of the main fuel) and burn downwards thus creating the wood gas as it burns down and the gas burns as it rises exits out of the twin wall holes at the top of the stove.

[Ashley Cawley]

Here's my 10 pennies worth...

As a general rule, Wood gasification stoves usually rely on burning a single load of fuel (wood, cones, pellets etc) and once the fire is going, you wouldn't add more fuel to it.

Also, they tend to be lit from the top (kindling at the top on top of the main fuel) and burn downwards thus creating the wood gas as it burns down and the gas burns as it rises exits out of the twin wall holes at the top of the stove.I can see the top/down theory now! Thanks for explaining :)

Yeah it's worth noting Kieran that ironically it's not just the wood that's burning! Sounds silly I know but if you think of it like this; the heat of your fire or ember heats the wood which makes the wood expel gas, it is this gas which is combustible and burns if there is a heat-source hot enough to ignite it. When you've got a good fire going and there is a lot of heat the wood literally gets converted from wood into a gas form as it's heated and it is those gases that burn.

[Kieran]

I can see the top/down theory now! Thanks for explaining :)

Yeah it's worth noting Kieran that ironically it's not just the wood that's burning! Sounds silly I know but if you think of it like this; the heat of your fire or ember heats the wood which makes the wood expel gas, it is this gas which is combustible and burns if there is a heat-source hot enough to ignite it. When you've got a good fire going and there is a lot of heat the wood literally gets converted from wood into a gas form as it's heated and it is those gases that burn.

Yeah, I get that. Learnt about it in Science.
Thanks Ash & all the other guys that have posted.

[MikeWilkinson]

Just quickly built and test a new one in my lunch break, Used two heinz soup cans, small diameter one and normal can, the pull top made it real easy. After a few mods got a really nice set of blueish flames from the gas jets (depends on fuel). He is what was observed :-

As intial fire creates bed of ember - air is being drawn up through the wood pile and you get a normal burn.

Initial flames create coal (pyrolysis layer) bed which now sits on top of fuel pile but below the gas jets.

Air in side wall of cans heats up and begins drawing cool air up from base and into flame at top stove.

As air is drawn up it creates a vacuum effect, pulling some woodgas down through the wood pile and up the side wall, where it mixes with air.

Wood gas begins to burn instead of actual wood.

As this process increases, the wood begins to burn in a less oxygen rich environment creating charcoal and releasing more gas - Think of the plume you get when making charcloth. More gas is being drawn down and around the sidewall creating a super hot flame at the gas jets - really noticable towards the end of the burn.

Once all the gas has been burnt off, the charcoal then smolders - gives a slight simmering effect.

Finally all fuel is burnt and you are left with a little bit of ash.

Overall a very efficient use of fuel, that produces a good hot flame and little smoke and almost completely consumes the fuel so little waste.

My camera batteries are knackered at the moment, but as soon as my new ones arrive I'll get some construction photos and working photos.

The great thing is I can flip the whole assembly upside down and use the base as my priming pan for my penny stove, so for the sake of two coke cans, two soup tins and some wire for the pot stand I now have an efficient, compact multi-fuel cook system capable of burning wood, spirits & Solid fuel tablets. Love DIY Kit.

[MikeWilkinson]

Photos of the above.

105102104103101

[paul standley]

The great thing is I can flip the whole assembly upside down and use the base as my priming pan for my penny stove, so for the sake of two coke cans, two soup tins and some wire for the pot stand I now have an efficient, compact multi-fuel cook system capable of burning wood, spirits & Solid fuel tablets. Love DIY Kit.

Mike, you are legend in your own lunchtime and a man after my own heart....!

[MikeWilkinson]

One last thing about these stoves from me...

The smaller you go the more important wood selection is. A bigger system is a little more forgiving in using cooler burning woods/ damper woods than the small units. The small units need to stay hot enough to keep the flow of air going through the sidewall, any cool spots in the burn and you lose the wood gas burn and end up with a very smokey smoldering. Use really dry wood and keep the fuel size relatively small.

[Martin]

One last thing about these stoves from me...

The smaller you go the more important wood selection is. A bigger system is a little more forgiving in using cooler burning woods/ damper woods than the small units. The small units need to stay hot enough to keep the flow of air going through the sidewall, any cool spots in the burn and you lose the wood gas burn and end up with a very smokey smoldering. Use really dry wood and keep the fuel size relatively small.

Interesting point there Mike. When I tried my Bushbuddy out last weekend, I noticed that, when I fed it with larger, wetter wood, it smoked a lot and the fire nearly went out. Not really surprising but a good observation nevertheless.

Martin

[paul standley]

One last thing about these stoves from me...

The smaller you go the more important wood selection is. A bigger system is a little more forgiving in using cooler burning woods/ damper woods than the small units. The small units need to stay hot enough to keep the flow of air going through the sidewall, any cool spots in the burn and you lose the wood gas burn and end up with a very smokey smoldering. Use really dry wood and keep the fuel size relatively small.

Yep, I agree with that... It's a critical mass thing, small gasifier cans/stoves can't maintain a viable body of heat energy below a certain physical size and can't burn for too long on a charge of fuel which is why I've not really used them as a trail stove because to get a decent size and sensible burn time, the stove size becomes a bit too big for backpacking fo me.
Single wall hobo can stoves, or honey style stoves etc.. whilst being less efficient, are light and can be small and can be fed with fuel indefinately. You Pays your money and takes your choice...!