Trash Dumpster charcoal Retort Kiln Design
This is our charcoal retort made from a trash dumpster that is laid on its side and set on legs to lift it about two feet off of the ground. The dumpster is surrounded with thin sheet metal and there is a space of two inches in between the two where the flames traverse. We fuel a large fire underneath until the wood releases flammable gases. The gases spew from the bottom of the door and are directed into the firebox and will keep the fire burning until the charcoaling is complete.
Makes maybe 1/2 ton per firing.
Unloading from the roll-back. This photo gives you a better idea of the size and construction method.
Where did it come from?
A couple of years ago some of the younger local fire fighters were setting dumpsters on fire so that they could get overtime pay for putting the fires out again. Hey this was an improvement, before dumpsters they were in the habit of lighting off abandoned farm structures and remote log homes. Anyway the dumpster was evidence in the court case and when that was over I asked the county for it and they said sure. In general, old dumpsters are readily available at large metal recycling operations. But check your local landfill first, they might have a few holey ones sitting around.
If you’re into charcaol, I highly recommend building something on this scale. Originally we were making charcoal by the barrel but the dumpster method is infinitely easier since it’ll hold boards up to 6 feet long. If you happen to be located near a wood molding or flooring mill take advantage of the fact that the cut-offs are worth practically nothing these days.
Action shot please?
I don’t have an action shot. We have learned that for compatibility-with-the-community we should run this thing during the darker hours and we call 9-1-1 before hand to tell them that there is no need to send the fire department up to the mountain again!
Here’s the requested action shot:
Peter- no, we never used propane.
We’ve run this thing for 7 or 8 years now, I hope the recent round of repairs gives us 7 or 8 more! The main thing I wish we’d done differently is support posts in the middle of the firebox to prevent the pretty severe sag. But it works quite well, and it doesn’t take much longer to cook than our barrel-sized ones did.
You can see that after she gets going, there’s not much smoke.
Quote: So that smoke stack is venting the inner chamber, not the fire box?
Chris, the smoke stack is venting the firebox through the space between the inner chamber and the outer sheet metal. The rest of the flames in Lee’s picture are volatile gases from the inner chamber that are leaking around the door.
Quote: It may be worth my while to come down and “borrow” that thing some time. I doubt I can get away with it in suburban Alexandria.
A charcoal retort would fit in really well with all of the other Fire & Brimstone equipment. And there are a bunch of you bloomers and buttons guys up in that area. Maybe you could cook something up. I hope Kerry doesn’t read this thread!
I ran this last weekend, thought y’all might want to see the final results. I removed about 50 lbs of charcoal before I took the picture.
Question : how full was that and how much shrinkage do you get?
My guess is that’s about 600lbs, that’s not much better than a guess. I think we often get about 800 lbs or even more from this retort, but this one was 1)mostly white pine, 2) not as tightly packed as some runs, and 3) had a little more loss from burning as a kiln (see below).
I sometimes run this as a combination kiln and retort. The evening before the main run, I burn a fire under it for several hours. When that dies down, and the retort is not pushing out gases so fast, the wood in the retort starts smoldering. I let it do this overnight, and then finish it off by cooking as a retort the next morning until it’s done, and then caulking the door tight. I let it run as a kiln longer this time, the white you see in the center of the box is ash from the time it smoldered as a kiln.
The advantages of doing it this way are that it’s a bit less labor and fuel stoking the firebox, and it gets a lot of the smokiest part done overnight, leading to fewer visits from the fire department. Disadvantage, is of course, a little less yield.
Hope this helps- a sketch cut through the center of the retort from front to back. There are 3 exhaust pipes from the coaling box into the fuel box, I think they are 2″ d pipe.
I don’t think there’s much special about this design that bears copying, particularly. It’s main advantage is its size. The biggest mistake we made was not supporting the coaling chamber well enough, which led to lots of distortion and leaking problems. But it works.
Thanks Skip Williams for the good kiln design , questions and asnwers
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