I have been involved in a local school (Portland Waldorf School) which has a blacksmithing program. There have been complaints about the smell of the coal burning and so I found out that charcoal can be used as the fuel instead of coal/coke. So I am building this charcoal maker so that the children can see how to blacksmith without coal.
There are health benefits too! Coal produces sulfer when burned which can combine with water in your lungs creating sulfuric acid (acid rain) as well as the water in your sweat. If this helps someone have a better experience blacksmithing, I will be happy.
Here I describe how I made a charcoal retort. This is also known as the "indirect" method of making charcoal. Basically you take a metal container and cook it until all of the volatile gasses leave the wood.
Step 1: Make the Container
I decided to go ahead full bore for my first charcoal attempt. Many online sources indicate that they started out with small metal containers, but I figured a 55 gallon drum would be the best bet. So I found a recycled drum merchant on craigslist, paid $25 for a drum and proceeded to cut into it.
I took some 3 inch round steel tubing and made the retort tube.
This is a tube which takes gasses from the wood as it is heated, and redirects them to where they can be burned to add to the heat for charcoaling the wood.
You can see from the image that I made the bends using miter cuts. If you don't have the tool to make these cuts, you can use Black Pipe and fittings. That would increase the cash outlay, and since I had this stuff waiting for a use, I used it.
Step 2: Provide Holes for Gasses to Escape and Burn
Next, you need to provide holes in the pipe under the drum. The point is to create a large burner-like thing.
I drilled 1/4 inch holes every 3 inches in both sides of the tube. Later I thought that might not be enough so I used my die grinder to cut 3 slits in the top of the pipe so that the gasses would be directed more directly at the drum.
Step 3: Collect Wood and Take Your Stuff to the Burn Site
At first, I figured on using all pallet wood. So I loaded everything in my van to take it to the burn site.
Below you can see that I have everything loaded up and ready to go
Step 4: Load It Up and Cover It to Keep the Heat In
On my way to the burn, I realized that I did not have any way to keep the heat in the drum.
So I stopped off at Lowes and bought 3 pieces of cement board at $9 each.
You can see that I put a tray below the assembly in an attempt to have a low impact on the site.
I did not want to burn the grass where I was doing this, and we had a copper fire place on hand.
I think this detracted from the overall effeciency, however, so I would not do this again.
Step 5: More on Trying to Keep the Heat In
Here you see the cement board leaned against the assembly.
I have some left over KaoWool (kiln refractory blanket) from a forge project so I draped that on top to keep the heat in the drum as much as possible. I draped chains over it to keep it on the drum
Step 6: Load the Drum With Wood
Here we put some wood in the drum.
this is Fir heartwood which my friend uses to heat his home. They are mill ends from a plywood mill.
We filled the drum that much.
Step 7: Start a Fire
Pile wood up under the drum and set it ablaze.
An old indian showed me how to start a fire without flint, steel, paper or tinder.
He called it a weed burner and it's fuel is propane.
It works real well.
Step 8: Burn for a Good Long Time
we lit the fire at 10:30AM and did not see gasses come out of the tube below until about 3PM....
We wound up burning about 5 pallets, plus 2 moving boxes full of scraps from the school's woodshop.
Probably about 150 lbs or so.
There is about 120Lbs of wood inside the drum.
not as efficient as I had hoped...
Step 9: Examine This Video
Step 10: Watch Out for Too Much Smoke
this really does not smoke much. See the picture.
Step 11: Enjoy Charcoal!!
I really can't believe this worked!
Enjoy some awesome home made charcoal!!
for more information enjoy these google results:
Step 12: Updated Design of the Kooker
I decided that even though we were successful, that the process could use a major improvement.
The first burn lasted about 6 hours and consumed what seemed like a lot of wood.
I figured if I insulated the space around the Barrel that the heat would concentrate more on the container and the result would be faster conversion time and less wood burned.
I was right.
Here are pictures of my updated burner. The walls are one inch thick refractory cement. I used about 6.5 bags of refractory which weigh 55 lbs each. (So now the kiln / retort weighs at least 350 pounds!!)
You can see in the photos the steel structure and the refractory walls. I welded 1/4 inch round bar between the members as rebar and also tied chickenwire to those bars for supporting the refractory cement.
The front is bolted on so that it can be removed when the barrel wears out and needs to be replaced.
The floor is just the ground, and I laid down a piece of hardy-backer cement board to protect the concrete there. I added a hinged plate of steel there as a "fire box" door. It is about 1/4 inch thick and when closed there is about 4 inches open below it.
When burning it gets red hot as do the steel members of the structure!!
I also added a hole in the top as a place where the smoke can emit. I plan to add an insulated chimney to it there in the hopes that the fumes coming out can have a secondary burn to perhaps make less smoke. The chimney will need to be very well insulated for this to occur, so I plan to make it a double-wall arrangement probably 10-12 inches diameter outside with a 6-8 inch diameter inside pipe, and fill the gap between with kaowool or perlite.
The next step will be a short video of this one burning.
Step 13: Video of New Kooker Burning
In the morning I discovered that 100% of the contents had converted to charcoal!!
The pile of wood in the picture below is what I took from to burn in the firebox. It is mostly still there!
So I don't know for sure, but I think I burned less wood in the firebox than was in the barrel, which is a huge improvement! The next burn will have more science. We will weigh the wood placed in the barrel, and note the type of wood. We will also weigh the wood burned in the firebox and then weigh the charcoal produced and time the process again. This process should give us a much better idea of the efficiency of the improved process.
Thanks for watching!