Hello all, I have had my woodgas project on hold here over the winter, as the new hydro setup was so successful that I didnt need a backup generator even once this season! In fact, I dont think my batteries have dropped below 90% (when the hydro shut off in the night from a clogged intake). Anyhow, I still have a big stockpile of charcoal wood, so I decided to make some time to burn it down before the dry season sets in. Charcoal making seems like a winter-time pursuit.
I did run a batch in my horizontal retort, and I am still not happy with it. Too much smoke leaks around the lid, still takes too long to get going, etc. So, here is another project I have been working on.
I am calling it the the Tandoor - basically it is an old burned out barrel that I have lined with clay. I was inspired by the guy who makes the Primitive Technology videos on youtube. I think his video on charcoal making has been posted on this forum before. Anyhow, my thinking is to use free and abundant materials to extend the service life of the steel components, and also, playing with mud is fun. I did not do due diligence with the clay I used, and it shrank like crazy. huge cracks everywhere, but thanks to the steel shell, they couldnt really fall apart. For this test, I just crammed in more clay and went with it, but I have made a test brick that has mix of sandier soil blended with the clay, and that looks a lot more promising. The drum has like 8-10 ~1" holes in the sides to let in a draft, but I think it needs more. I also wrapped it in some leftover insulation.
Yesterday I did a test batch, using some sheet metal for an afterburner, and it did pretty well. I poked air holes in the afterburner, but that proved insufficient as well, and I had to lift it up on a couple of iron bars to get it to burn off all the smoke. Once it was dialed in, though, it ran very cleanly.
To shut it down I spread a layer of damp ashes all around the lip, and set down a 2’ square of maybe 1/8" steel plate. the drum is not very even, but it sealed tolerably well. About an hour later when i checked on it i could see spots where some smoke was escaping, so i plugged it with clay. The coals were still warm today, and started to relight when I opened it - so i shoveled them over into a drum and sealed them up.
I got maybe 1/3 of a drum - I didnt sift out the ashes yet (there was a decent amount in the bottom) and there were a few brands in there that I will have to pick out when it cools. it was not hard to shovel it out, I found a 90 degree stovepipe elbow made a good scoop for the stuff on the bottom.
I would say I am optimistic that this system has potential, and I am going to try some more experiments with clay. The possibility of a ceramic lid/afterburner intrigues me…