Mini charcoal retort - Mk2

[Chris Sheppard]

After havign completed several burns with mk1, with only one that ended up as a pile of ash, I decided to have a go at Mk2, usign a 50kg gas bottle this time. The hope was to double the amount of wood produced but in the same time scale.

 

Because of the weight of the canister when full, I went for an top lid rather than a closable bottom. Lid is made from an old rim with the holes welded up. Originally cut some holes in the base for the gas to escape, hoping it would burn hotter and faster but found with the first burn it wouldn't shut down and it was still hot a couple of days after - they got welded back up.

 

So, last night was the first proper go at it. Loaded it up with mainly birch poles and a few alder around 80cm long (only felled in the last few weeks so was keen to see how that affected it too) and filled what gaps I could with a few logs out of my shed, though it was still quite loosely filled. Dropped the lid on and lit a fire in the gap between the retort and the oil drum and loaded in a few lumps of old slabwood to get it going.

 

Was a bit smoky to start with (figured it might be) but once the fire got going the smoke died down fairly well.

 

Started to get the escaping gas igniting after around an hour and a half, which was quite good I thought with it being green.

 

Left it burning and in the morning it had cooled down enough to open and empty - result.

 

Got double the amount of charcoal than the smaller one would produce and in a similar time with similar amount of fuel - all good. Only had one bit of unconverted wood and that was a biggish lump of alder, which was probably quite wet anyway

 

I know it looks like I'm just messing round in the garden (which I suppose I am) but am planning to use the same method to make a bigger, easily poratble kiln for in the wood that will run off brash so making burning up produce a product at the same time as we've loads of charcoal sized timber to go at. What I like about this method is it's a bit more foolproof and looks after itself rather than needing quite as much attention.

 

Few pics for anyone interested

[Sam Thompson]

Cool stuff I might even give that a go myself

[Dean Lofthouse]

That dog needs shaving Chris

[Ty Unnos]

Looks good. I was at CAT yesterday and they have a home made retort. Have you seen it?

 

The CAT one is an oil drum inside a big metal tank. But they have a pipe for the wood gas to escape and feed into the fire.

 

Does yours have any way for the gas to escape?

Edited June 27, 2011 by Ty Unnos

[Chris Sheppard]

That dog needs shaving Chris

 

She's on tablets for thyroid - it grows like mad

 

Looks good. I was at CAT yesterday and they have a home made retort. Have you seen it?

 

The CAT one is an oil drum inside a big metal tank. But they have a pipe for the wood gas to escape and feed into the fire.

 

Does yours have any way for the gas to escape?

 

I've not seen the one at CAT but had heard about it, I'd like to go bigger than that, like an oil storage tank inside another.

 

The first one, the gas would escape through the join where the base was hinged and so the gas was fired into the bottom of the fire - this one, the gas comes out under the lid at the top, but because of the overlap seem to be sent down with a bit of force so is still working. That was my idea with the vents in the base of it but they didn't work and it wouldn't shut down itself

[Ty Unnos]

I am also thinking about building my own but for now am using a ring kiln.

 

What surprised me about the CAT kiln was it had a single 2" pipe for the gas to escape coming out of the oil drum. Also with the drum on its side the pipe was coming out the bottom near the front.

 

I was expecting lots more holes and to have them at the top! Anyway maybe the answer is to have a single hole rather than lots.

[Ty Unnos]

The CAT kiln:

 

Biochar at the Centre for Alternative Technology: business opportunity for small woodland owners or climate change solution | The Woodlands.co.uk Blog

[Chris Sheppard]

I am also thinking about building my own but for now am using a ring kiln.

 

What surprised me about the CAT kiln was it had a single 2" pipe for the gas to escape coming out of the oil drum. Also with the drum on its side the pipe was coming out the bottom near the front.

 

I was expecting lots more holes and to have them at the top! Anyway maybe the answer is to have a single hole rather than lots.

 

The idea of the hole facing down is to feed the gas into the base of the fire I'm guessing - then as long as there's heat, the whole thing is running off it's own gasses.

 

What puts me off a ring kiln is that I'd have to keep an eye on it, it's not as efficient, and they are well expensive.

 

The CAT kiln:

 

Biochar at the Centre for Alternative Technology: business opportunity for small woodland owners or climate change solution | The Woodlands.co.uk Blog

 

That link was quite helpful - managed to find a video of theirs working.

 

I really could do to find some of those barrels with lids

[renewablejohn]

If your anywhere near Bolton I could let you have a couple of barrels with lids.

[wills-mill]

Very cool, good effort!

 

I read something on the 'net from a chap who was insulating his retort or oil drum to keep things even more efficient....