Is there a market for a small, cheap charcoal retort?

[agg221]

Would your planned design lend itself to scaling to a 200l volume? It's a useful size as there is a lot less cutting needed and it will still make a reasonable volume from the smaller, less straight material.

 

Having spoken to people about fast burns, I understand there can be issues with getting a good quality material. There is a tendency to break up the structure of the wood too much, making it powdery. You also have to allow a certain time for the volatiles to diffuse out from the centre of the wood as it chars, otherwise they remain trapped and recondense in the middle. This would place limitations on the thickness of wood you could process and may mean it wasn't suitable for certain species.

 

Any thoughts?

 

Alec

[openspaceman]

Having spoken to people about fast burns, I understand there can be issues with getting a good quality material. There is a tendency to break up the structure of the wood too much, making it powdery. You also have to allow a certain time for the volatiles to diffuse out from the centre of the wood as it chars, otherwise they remain trapped and recondense in the middle. This would place limitations on the thickness of wood you could process and may mean it wasn't suitable for certain species.

 

Complicated subject but yes you are right in that slow seems to make better charcoal, the Japanese ritual charcoal left the sticks intact, just slightly shrunk, and this was made from green over a period of days.

 

However you waste too much of the raw material making char from green wood in evaporating water in a kiln.

 

It isn't so much allowing evolved volatiles to escape but rather that they undergo cracking reactions whilst still in the wood matrix and are deposited as char inside the cell structure.

 

The general rule is you increase yield with larger pieces cooked slowly, increased pressure also increases yield, our kiln produced good beech char from 15%mc material at 40psi.

 

The corollary is in gasification if you subject the smallest material, such as sawdust, to a rapid rise in temperature, >1000C/sec, you end up with very little char and that is mostly ash, the off-gas evolved at such high temperature doesn't have time to react and thus CO and H2 dominate.

[timbernut]

I reckon the ideal material for this retort would be produced by a branch logger? I've been thinking of getting someone to make me a wood burner to run specifically on it as well as filling my ring kilns with it. I'd be well happy replacing them with a smallish retort for quicker turnaround

[Woodworks]

Would your planned design lend itself to scaling to a 200l volume? It's a useful size as there is a lot less cutting needed and it will still make a reasonable volume from the smaller, less straight material.

 

Having spoken to people about fast burns, I understand there can be issues with getting a good quality material. There is a tendency to break up the structure of the wood too much, making it powdery. You also have to allow a certain time for the volatiles to diffuse out from the centre of the wood as it chars, otherwise they remain trapped and recondense in the middle. This would place limitations on the thickness of wood you could process and may mean it wasn't suitable for certain species.

 

Any thoughts?

 

Alec

 

Thanks Alec

 

The charge chamber is a 200l barrel. Not had any problems with 2 hour burns and had lots of compliments on our charcoal. Only been using small wood from the branch logger and not yet tried it with larger stock so sounds like I best do some tests with that.

 

Timbernut

 

Yep branch loggings make great charcoal and use material that might otherwise get wasted

Edited July 10, 2016 by Woodworks