Retorts

[Selph]

Is there an agreement around here about which types of charcoal retorts work well? I saw the Hookway thread, and there's a few others around that I looked at. I've got a lot of wood scraps from milling up logs and taking care of the woods at my parent's place (and our own baby woods). Not looking to make a ton at once, more along the lines of medium-sized batches.

[pnut]

What method did you settle on?

I prefer using a kiln versus a retort. I build a fire around a sealed drum of wood with holes in the lid. When white smoke stops coming out of the holes I cover them with dirt to seal them up and let the fire go out and wait for it all to cool.  It produces pretty good quality charcoal and the yield doesn't seem too bad either. 

Pnut

[Frosty]

Selph's last post was almost a year ago pnut, I don't know if he's going to let us know how or if he's had any success. The pandemic may have put a halt to his activities for now. <sigh>

Frosty The Lucky. 

[pnut]

I know. I was just going through some old content I was following and thought I'd check since he's been active recently. 

Pnut

[pnut]

12 hours ago, pnut said:

thought I'd check since he's been active recently. 

*Logged on* recently. 

Pnut

[Selph]

I just started to look into this again (and found this old thread!). The pandemic did indeed hamper my ability to do much, but it was more the remodel for my FIL to move in with us that put things on hold. It took almost 2 full years of fun stuff like this away from me. I will put some effort into keeping track of exactly what I end up doing. I should spend more time here now that I can work on stuff regularly again. This is the best source of blacksmithing information on the internet, in my opinion. I'm hoping to order steel tomorrow or the day after, so I'll end up settling on something here soon. Or I suppose I could order the steel for the forge build first and then figure this out afterwards.

I'm trying to figure out now if I should go the big route and use a 55 gallon drum or if making a series of medium-ish batches makes more sense for me. That decision will probably dictate exactly which direction I go. I do have an old hot water heater we just replaced in the basement that could potentially be salvaged, I'll have to see if others have done that and what it entails.

[Frosty]

A used 55gal. drum with clamp on lid can be had here in Alaska for about $15-20 and holds how many times as much as the small container you're thinking about using? I don't know what you looked at but it's a really simple retort. Better still it uses the "indirect" method so your return is about as good as it gets. You need 1ea, 55gal clamp lid drum, preferably with a bung in the lid. If no bung you'll need a 2" floor flange and hole saw.

1ea, 2" 90 street elbow.

1ea, 2" 90 elbow.

1ea. 2" nipple that extends from the bung position past the edge of the drum body, give it an extra inch or two.

1ea. 2" pipe nipple 6"- 8" long. This will bring the end of this nipple over the edge of the drum and extend down the side a couple inches.

8' of stove rope. 

Dig a trench a little longer than the drum leaving one end pretty straight up and down, the other can be sloped down to the bottom. 

Depending on what sheet steel you come up with to cover the retort will determine how deep you dig the trench, it should be enough wider to provide a few inches of space around the drum, 4-6" is good. 

Across the bottom of the trench stretch a couple few pieces of steel bar, black iron pipe, etc. to provide a clear space under the drum. 

Load the drum with wood as closely spaced as reasonably possible WITHOUT making it a solid mass, stacking lumber face to face doesn't work well. Yes? Once packed place the stove rope in the lid's gasket space, clamp it on and lay it in the trench bung facing the sloped end at the bottom with the pipe aimed back under the drum. Pack the space under and around the drum with slash or scrap wood. Doing this BEFORE placing the drum in the trench is a good idea if the trench is a close fit.

Cover the retort with the sheet steel cover with a small gap at the rear end. The cover is to contain the heat but it doesn't need to be sealed. The front of the retort should have another piece of sheet steel covering the it's end to help contain heat and help direct the flames.

Light the wood under the drum, kick back and keep an eye on the fire. After a while smoke will start coming out of the pipe under the retort, how long depends on how dry and the size of the wood in the retort. The smoke will ignite and burn like a gas flame. When this starts stop pushing wood under the retort. It is now a self supporting process and will continue until the volatiles have been driven out. When the flame goes out take the cover off the retort and plug the end of the pipe with something to prevent oxygen from entering the drum but WILL NOT make an air tight seal. Dirt is good if you can pull it with a hoe to cover the end. Whatever it needs to be blocked.

It will be cool enough to open in a couple days if you don't want to open it and quench with water. Water will evaporate off leaving dry charcoal.

That's it a 55gal. indirect charcoal retort. Expect up to 35-40% loss by volume.

Using the wood in the retort for the heat source is called the "Semi-direct" method. Because you're burning some of your wood for heat the loss will be greater IF you do it really well, it CAN be a total wash if something goes wrong. Fall asleep when you should close it up for example. 

Shoveling coals out of a fire is the "Direct method" and in many cases the better source. Say you're camping and want to do a little smithing, shovel coals out of the camp fire. You won't have to pack a bag of charcoal with you. Hmmm?

Frosty The Lucky.