[TheForge] charcoal

[Jerry Frost]

Bob:

There are a number of different techniques with two main differences. Direct 
and indirect combustion.

Direct combustion is basically lighting the wood and controlling the air 
till it's cooked.

Indirect combustion involves putting the wood in a relatively airtight 
container and keeping the fire on the outside. When the wood begins 
outgassing you redirect the "smoke" into the outer or fire chamber and burn 
it.

Returns for direct combustion run to 20-30%. Returns for indirect run 
30-50%. A lot depends on your technique, dilligence, etc.

A 55gl drum with the clamp on lid works nicely for a small scale operation. 
Replace the rubber gasket with stove rope gasket and plumb the bung so it'll 
redirect the "smoke" to the combustion air intake.

The set up can be very basic with the drum simply propped up on a few bricks 
and a fire lit under it. If the drum's on it's side it'll get more heat from 
the fire but you'll need some plumbing to direct the "smoke" back under it: 
a nipple, two elbows and a couple various lengths of pipe in 2". If you 
stand the drum upside down the bung will naturally be under it in the fire 
zone but you'll need a bigger fire to get it going.

Kep it burning till the drum stops smoking then stuff the bung with 
fiberglass insulation to stop the air. If you screw the bung plug in, it'll 
stop the air alright but the vacuum as it cools might collapse your drum 
though it's unlikely with stove rope as a gasket under the lid. . . Still.

If you have some scrap sheet steel like metal roofing laying around then 
it's easy to move to the next step in efficiency and enclose the drum in a 
chamber. Adding some insulation will improve it again.

I salvaged a 500gl. fuel oil tank a couple years ago and as soon as I find a 
300 gl tank for the same $ (free<grin>) I'll make my charcoal retort. 
Indirect method. Maybe I'll really luck out and find a 700-1,000 tank. 
WooHoo.

Prepping the wood is more important than wood type. You want dry wood no 
more than 4" thick, length doesn't matter within reason. There's a lot of 
disagreement about hard wood vs. softwood but it's only true to a degree. If 
you check out one of the firewood URLs or a pocket handbook you can see 
exactly which woods make the most heat/lb. Mineral residue is another 
consideration though it isn't a major factor outside some wood types. For 
example the cottonwood we have around here is terrible firewood. Even dry it 
has a low BTU and high mineral content so the main way it warms you is 
cutting, splitting, packing and cleaning the stove. Any of our softwood 
species is preferable to the local cottonwood.

Anyway, in practical terms the rule of thumb is: the better the firewood, 
the better the charcoal. Even this is a misnomer, all charcoal that doesn't 
have a high ratio of mineral content is equal, lb. vs lb. Where you'll 
notice the difference is the return when you're making it.

If on the other hand you're into making fireworks and or gunpowder, purity 
and consistency makes all the difference but if you're making fireworks 
there's nothing I can tell you. <grin>

Frosty
-------------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

http://www.artmetalradio.com/

From: "Bob Smolen" <boka at mwt.net>


>I have some cull logs and wondered if anyone has tried making charcoal and
> is it worth the effort? I use gas and also like coal but it would be nice 
> to
> make own fuel if practical. There are a lot of sawmills in the area and I
> can get trimmings cheaply, but is there a lot of work once you have the
> wood?
> Thanks,
> Bob
>