When feasible, it is highly efficient to further use the energy produced by running the retort. The unit re-burns
gas to continue the retort processes. Further use of the produced gases could fuel an engine/generator or a
boiler (details on these optional techniques are outside the scope of this document).
I think you would be better off to enclose the retort in a firebox and use the retort gasses to provide most of the conversion heat required. There are a lot of retort ideas around but the one i’m proposing that has been done a lot is basically a barrel in a bigger barrel with twigs and trash wood taking up the extra space. Light the trash and it heats up the inner barrel retort to the point that the inner barrel gases ignite and drive the reaction. I believe your proposal is a lot of filtering and cleaning that would remove most of the benefits of the simpler fuel that is charcoal.
Yes I like how many designs recirculate the gasses to fuel the charcoal production cycle. I currently make charcoal in an even easier method of TLUD (aka fill a barrel with wood and poke holes in the bottom and light from the top).
I thought it would be nice to have the tar as a byproduct, I hear it is good for fence posts
You could dedicate a retort purely for distillation and still use the excess gas to self heat the retort. But you’d likely want water cooled condensers. Imagine an alcohol or essential oil still. All the byproduct would be useful in some way, but if you want a lot of charcoal you’re best off with a TLUD like you have now or a full self heating retort in my opinion.
This Spring I was planning to do just that. I have a 30, 16 and 10 gallon drums to play with. The inner drum I was just going to install a center tube so the gasses excape at the top and migrate down the botton and exhuast out. The Ill create a fire chamber basically just a ledge for the inner drum to rest on and then opon chamber to feed fuel into. Then chimney out the top. MIght intall this in the shop for shop heating. When done we will just have to fire up the torpedo heaters to let it cool down to where we can handle it and install a new batch of wood. Could have mutliple inner drums ready and you just swap them out.
What you are proposing is a ‘closed’ retort. IIRC there is a thread on wood vinegar, which is essentially what you are aiming for, but I think there are several video’s in there of various ‘still’ designs. Most of them use a long pipe with a slight vertical rise for the condenser. sometimes they drape wet clothes on the vertically rising pipe. Or some just use a water bath cooler.
I should mention, that typically, they collect everything, then let it settle out, and in theory (I didn’t get it to work right but that isn’t completely unsurprising) that it settles out into 3 layers over a few months, the bottom layer is the tar, the middle layer is the wood vinegar, and the top layer is mostly water.
Because it is distillation with a pot still, check your local laws about having a ‘still’.