Charcoal retort à la Johan

General Discussion
#43

Hi Johan, yes, ofcourse posting the link is ok :+1:
About my tar trap, no, i don’t collect very much, around 0,5-1 liter every burn, and some water, the tar is very thick, like pitch (beck), this is mostly because i take out the gasses in top, and have heated bottom, this gives pretty bad, black tar. To catch good tar, it should never boil, just sweat out of the wood, and run out the bottom.
Another reason is the gas pipe from top down to tar- trap should be water-cooled, this was the plan, but the stainless 6 inch pipe i cut to lenght, and put in water-hose fittings, was still standing in a corner when i had welded everything…(at that time i always had a steady supply of cold beer in my shop, and i forgot everything, welded besides the parts to be joined together and so on.
Many sad surprises when i entered the shop next day, with headache and sore eyes :roll_eyes:

Forgot some, i have had my eyes on a pretty big, round tank (farmartank) for a while, i really want to build a big, horizontal retort, which i can collect all the tar, turpentine and some methanol. By cooling the pyrolyzis gas down to 60°c all thats left is whats called un-condensable gasses, and there is plenty enough to sustain heating.
Needs fairly amount of cooling water, but it’s easy to solve with a small pump, near a lake or stream.

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#44

Pretty much what I was thinking, to be able to get as much value out of the pyrolysis as possible. I had no idea of the temperature needed though and if I understand correctly, do you mean to cool ALL the pyrolysis gasses and lead what cannot be harvested back again as fuelgasses to sustain the fire or only cool part of it as I was thinking?
If so, that is a lot of gas cooling from a big retort.

For a short while I was even also considering putting in a second sealed container in the chimney with a cooled slanting pipe out to try to harvest fuels from boiling HDPE plastics while charcoaling and utilize the heat even more.
Just combining the plastics to fuel thread with charcoal making.
Probably lots of nasties in the non fuel part released into the air, I know, and this is why it is only as a considering thought from a flu-affected runaway mind and easily discarded. At the same time I also know that if I dispose of this plastic it will get burned anyway only more controlled.

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#45

Yes, cooling all gas from the retort.
Other option would be a non-heated bottom funnel to collect mostly tars, with slow heating from beginning.

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#46

Hmm, a little trickier to fix. Probably easiest to have a dual fired kiln, one firetunnel on each side. Much like the mighty Kursk 3.0. :smiley:

Cooling that much tarry gas is also tricky. Perhaps a pipe in a barrel in a barrel and have water flowing on both sides of the gas slowing down a little entering a bigger space?
But this could cool the tar too much and not flow out… or not

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#47

I did a little thinking for exchange and drew a quickie picture of a retort with tarharvesting and turpentine/alcohol harvest, it requires watercooling for the latter harvesting but not the tar, it is inspired of the tarburning pits of the olden days but tweaked a bit and combined with a retort.

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It is on a centered pivot point for easy emptying, easy filling and gravityfeeding the tar to the outlet (adjusted idea from Göran’s retort)
Fully insulated and the two fireboxes start about 4” up from the bottom to not burn the tar and keep it a higher quality, the cooling of the gasses is optional wheather you want that harvest or not.

The size I had in mind is a 500l or 150 gallon tank, 50cm or 20” diameter and 170cm or 67” tall/long

What do you guys think, could this work?

This is NOT the retort I will build first but it is interesting enough to perhaps build some other time, the first one will be a straight forward charcoal retort.

I apologize for the flooding of my posts lately, the flu is starting to retreat so should be able to actually do stuff again soon. :smile:

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#48

Looking good Johan.
If it’s ok with you, may i post some ideas/drawings here in your thread?
Maybe some useful ideas.
And yes, i think your retort will work good.
Maybe risk of some half-charred pieces in the cool bottom, but that is no big deal, they could always be re-cooked the next burn, or used to heat the retort.
I’ve had thoughts about side fire-boxes just like in your drawing, also thinking about a central firebox, but that would be very exposed to heat.

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#49

Of course you can post your ideas here Göran :blush:

I was thinking that after the harvesting of liquids have been done the retort can be heated as a normal retort for charring. (There would most likely be a layer of baked tar in the bottom then)
I suspect the reason old blacksmiths liked the charcoal from the old tar producers because it burnt hotter is that it was not fully converted and still had tar in it but that’s my theory.

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#50

Johan, l can confirm charcoal is a ligitimate side buisniss, and a fun one too. Well the wife might not agree once she washes your clothes after a burn, and you may end up sleeping in the barn. But otherwise, great :wink:

If you want to sell premium bbq charcoal, kiln is the only way. The kolmila is tradition yes, but every single customer of myne prefers the kiln one. Its denser (not by weight-kolmila style usualy contains a lot of water or is not 100% pirolised), it burns hoter and longer.

Tlud is a no go. The fast process makes britle, soft charcoal, think popcorn. Good for gasifiers no good for grills.

If your doors and all the rest seal well you can just drill holes in the bottom. At the end of the run l pour 15l of water in the kiln and it pools at the bottom, boils and keeps the kiln at a slight overpressure as it cools, preventing an air to enter.

Overheated insulation is a risk! Pobably asbestos like. Its best if its sealed well. I got around this by covering it with fiberglas fasade mesh and plaster it with mortar (only maybe a cm thick).

The pivot is a good idea but whaever you plan regarding a kiln design always remember first that the kiln gets hot. Real hot. Basicly glowing. And blackdmiths are known for heating the steel in order to bend or reshape it :wink:

Going small at first is a good idea but may l sugest planing ahead, if (when :smile: ) you go to the biger kiln later the small one culd be used to kick start the big one so keeping that in mind culd save you a lot of wood and time heating up the big kiln.

Collecting tar l can not comment much as l too only scratched the surface, all l can tell you is that as long as you cool the gas well it will produce a lot. I dont yet have water at the kiln but when l do l think a water cooled condenser shuld produce barrels of the stuff.

For extra quality, ringung char, you want it to be exposed to high heat for a long time. Dry wood will produce the heat but not the time so l mix my wood, some dry, some thin, some green, thick… so that the kiln runs long an steady. Too much heat fast will make char britle and puffy, popcorn effect.

If l were to make a kiln again and if l had some actual level ground on the property l wuld make it on a trailer. That culd also solve your pivoting idea…

Have l missed anything? Probably, my inomniac brain speaking :smile:

Oh yes. Pipes/chimneys trugh the kiln only create problems. I found them unnessesery. Its a good practise thugh, as with everything in life, to no be greedy. Never stack your wood in the kiln, just throw it in there loose for all the heat currents and raiation to pass between them.

Giorgio, here you may own unvax chickens l belive. But any over 10 you shuld officialy report. Its the greed l mentioned above… the government is afraid of you selling a few eggs without them getin their claws in your profit…

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#51

You might check this out. They added a watercooler.

I honestly don’t quite get how yours works. You need to cool the ‘offgas’ from the retort. It looks like you are trying to run a cooling coil inside the retort. You need the retort to get hot. Then you condense the smoke coming out of it.

It is typically done with either a very long pipe sloping up, and you put a hole in it by the retort, and when it cools, it comes all the way back down into a container. OR you water cool the gas and collect the condensates.

This isn’t really a great example but it isn’t the worst either. I can’t find the ones I saw from like 10 years ago.

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#52

Sorry Sean, I see the confusion now on my drawing.
Where it says watercooling is actually the gas piping on the outside meant to be water cooled and then through a trap to collect liquids and the gasses lead back to the fire again.

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#53

The pivot is meant to be only on the tar and other liquid harvesting one that is less hot but you are right, I did not think of the softening of the metal there with all that weight. Could be an unwelcome surprise in the middle of a burn :smile:

Good thinking, there is not much extra work to run both instead of the big one while I’m at it, some tweaking involved to learn how much gas can be ‘stolen’ from the small one without getting less quality.

I have the thought of putting it on a trailer too, the small one I was imagining to make so it can be lifted on to a regular trailer but the bigger one permanently mounted on a tractor wagon chassis with support legs in the corners.

Great news about the chimneys through the kiln, I was hoping to get away from them. My mind was screaming cracks in the going-through welds :smile:

And the loose non-stacking just makes good sense to me to get the free flowing inside.
Good idea about throwing big ones and green ones in there as ‘sacrificial pieces’ for a long burn.
I think this gets easier with bigger size retort.

Thank you for the detailed experience Kristijan, much appreciated :blush:

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#54

Johan, Kristjan is a good charcoal stove maker, here is a sketch with an air-cooled method for collecting tar, just an idea, not tested ,… :slightly_smiling_face:

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#55

Good idea and good thinking with the aircooling.
If I recall correctly (Göran can probably confirm or correct me) back in the 1800’s the first tar produced is of lesser quality with too much water and so is the last tar which is too thick and a little ’grainy’ consistence. The high quality tar is brown and heated only to somewhere between 160 to 230C (320 to 445F).
As Göran said it is better to have the tar ’sweating’ out of the wood rather than boiling out but it also depends what the intent is with the tar you harvest, if it is for your own use perhaps the quality is not as important.
I have not read any newer papers about tar harvesting so I can’t say if it works good to harvest tar from a gaseous form if you make that the prime objective.

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#56

If I understand the process of gasification of wood correctly, I would state it something like this:
At the beginning, I must emphasize that I am talking about slow heating of wood, so that the processes slowly take place

-drying of wood and removal of excess water - water vapor, when all the wood is heated to about 120°C it is practically completely dry
-with further heating, various resins, oils contained in different types of wood melt, maybe Goran calls this that the wood “sweats”, these resins are probably released at less than 200°C
-above 200°C, “pyrolysis” begins, tar gas is released, which is in a gaseous state, with cooling some substances liquefy again, but mostly not, this is a very strong gas suitable for heating
-when we heat the wood towards 400°C, the release of pyrolysis gases decreases, there are fewer and fewer gases that are condenses into tar and finally remains only charcoal

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#57

Once it starts carbonising l think you may be able to steal probably 75% of the gas. The pyrolisis itself is exothermic (slightly) and with good insulation not much heat is needed to keep it going. I need to close the burn chambers almost completely when it gets going. If it get to much air its a huge steel melting runaway.

I forgot to mention one more trick for a faster startup, l have a channel on the bottom of the kiln that provides air in the bottom of the kiln (trugh all its leng). When the kiln is close to liftoff temps l will open the channel wich will alow air to enter and egnite some hot wood on the bottom. This will kick start the process and can shorten the heating time by hours.

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#58

I am pretty certain that you understand the gasification process perfectly Tone, no doubts from me :blush:
This sounds correct, I guess the biggest problem is temperature control in the kiln and proper venting of the water steam before any harvesting.

Wow. I would not have guessed that much

Doesn’t it smoke terribly cutting off the air, choking all the neighbours?

This is a very good tip that I would probably never thought of myself. It will surely be used.

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#59

Pretty much all is covered by above posts.
I forgot to mention earlier, but can confirm as Kristijan says: pivot is good and helpful, but needs to be for example taps welded on a steel “belt” heavy flat iron like a belt around the kiln, bolted together.
I know by my own experience, you could probably see in my youtube how the pivoting taps are really out of shape.
And yes, first tar is low grade, next, brown runny tar, super quality, last is more of pitch.https://youtu.be/FyBXBO6Ggyw?si=TVzSnAVQ1G7yyzam
This one is real good on tar making, has inspired me a lot.
Edit:check out his way to separate turpentine and water :smiley:

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#60

The reason is unclear to me but for some reason, as long as its burning, not much smoke is emited even if severely oxigen starved. Only if the fire goes out the amount and quality of the smoke is gloryous. I have gassed the whole village in the valley under me a couple of times :smile:

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#61

Very nice movie, a little hard to hear what the main person, Harry, was saying mainly because of the broad dialect (gotländska, I presume) but also from the lower quality sound. I remember those video cassette recorders back then, mid eighties. My grandpa had one :smiley:

A KISS setup as it should be, no bells and whistles and no overcomplicating contraptions. I enjoyed that movie a lot, thanks Göran :blush:
I loved the turpentine level checker, so easy. And the turpentine separator too, lots of ideas in this one.
The one thing missing was leading the cooled gasses back to the fire, perhaps they felt it to be too much uncertainty regarding temperature when doing it that way. But a separate charcoal unit using those gasses as a supplement in the beginning would work just fine.

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#62

A feelgood video, Göran. I couldn’t help but noticing it’s from 1986. Almost 40 years ago. Those oldtimers are probably long gone by now :pensive:
Funny though how around the 4 min mark, one of them is dressed in shorts only and his friend as if it was wintertime :smile:

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