Post by SA Hunter on Jul 17, 2015 23:27:29 GMT 8
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The design of this ‘wood gasifier’ stove is exceedingly simple and it can be built in under an hour using only empty tin cans and a few very basic tools (watch it in operation here). It would make a great little maker project with your kids; you’ll have great fun working on building this together, and will have a superb little cooking stove to use afterwards! The gasifier design is also a wonderfully compact and efficient stove, burning twigs you can collect yourself (rather than gas canisters), that’s ideal for cooking during a barbecue in the back garden or even on a family camping trip.
The gasifier stove is made up of a smaller can nestled inside a larger can, allowing air to circulate in the gap between them. Wood is loaded into the inner can as fuel, and as it burns it draws fresh air up through the bottom for a hearty, intense combustion – just like any barbecue. What’s unique about a gasifier stove is that it has a second, higher row of air holes that reintroduce oxygen. As wood breaks down in the heat of a fire it releases lots of gases and vapours and smoke that are all actually flammable, but would otherwise have blown away in a normal fire. But with this second row of air holes, fresh oxygen is drawn in and you get secondary combustion of all these gases. This means a gasifier stove is very efficient and releases all of the heat energy in the fuel, and is also smokeless when it’s running. Gasification of wood has been crucial through history, and can even be used to drive a car or van instead of petrol or diesel – there were over a million wood-powered cars across Europe during the Second World War!
Here’s how to make your own gasifier stove.
You will need:
one large can (the size of a normal paint tin)
three normal-sized cans (the size of an average baked bean tin)
drill
small metal shears
file
kitchen tongs
What to do:
GasiferStoveRemove the bottom of the large can, and empty out the contents. If you don’t have a can opener, see this neat trick here on how to open a can without using any tools.
Drill a row or two of large holes around the bottom of the large can.
Cut out a circular hole in the centre of the top of the large can, the same size as the normal-sized can. You can use the base of the smaller can as a template and etch (or use a marker pen) around the outline. You’ll find it easier if you drill a few holes just inside the outline and then use the metal cutting shears to snip around the circle.
Remove the top of one of the normal-sized cans. Drill plenty of holes into the bottom of the can. Also drill a row of holes about half an inch from the top of the can.
Use the file to take off any sharp edges or burrs in both cans.
Now carefully ease the smaller can down through the snug hole in the top of the larger can, as shown in the picture, so that you have one can nestled within each another. The top rim of the small can should be flush with the top surface of the big can, so that holes on the bottom are held suspended in the air.
Load up the inner can with some kindling (dry newspaper will work a treat) and just a small handful of twigs, broken into little pieces, and filling no higher than about half-way up the inner can.
You can help the stove get started by adding a flue on top of the combustion can, to encourage a strong updraft of air through the fire. Make a flue from a few extra cans and taking off both tops and bottoms. You can slot them together into a hollow tube about a foot long by snipping a short cut into the top of one can so that it can be squeezed slightly and slotted into the bottom of the next can.
Light the kindling in your gasifier stove through the air holes at the bottom, and be amazed at how quickly it gets going. You have a roaring fire to either cook with, or simply sit around in the evening! You can watch the operation of this kind of tin-can gasifier stove here.
The cans obviously get hot during operation, so be careful not to touch them and use the kitchen tongs to adjust anything.
