Kursk 3.0, new kiln

So, a while ago l had a litle misshap in my charcoal kiln…

An ember must of caught fire while l was at lunch. Resault was… well… not good. All twisted and bent… I somehow perswaded it to force it to kinda work again (read: introduced it to Edvardo, the 30 pound sledgehammer :smile: ) but cooking in it was so inefficient without insulation it made no sence no more. But l wanted to change some things for a while now so instead of fixing it l made a new one. Here is the end resault (kinda).

As you can see, l made a mantel around the thing instead of in it as l have before. More surface area, and l can feed it larger branches.
First fire (on the picture) was unsucsessfull. Rain caught me soon after l lit. Second burn too, l had to abandon it soon after lighting. Yesterday finaly l made it. It was still warm from the previous burn but still, l cant belive it took only 2 hours of intense heating to reach liftoff. And when it did, man that was intense… first of all it holds more wood now, and second, its heated more and the amount of gas produced was something to see… will film it next time.

Edit: you can see my loyal friend Edvardo on the last picture. He sometimes can perform magic :smile:


Very nice.
Is the chimney only from inside and the mantle acts like the chimney?
And it looks like it is open flames visible on the back side too, is that where you are leading the burnable gasses? There is no piping visible neither on the inside nor the outside.

I guess what I am saying, very good, very interesting and more info and pics please :blush:


Thank you Johan.

Yes the chimney is there just to get the tary steam off the face when loading.
Speaking of wich, there are 2 identical openings on each side, opposite to each other. For easy loading. Thats the glow you saw.

Gas goes down trugh a small pipe on the other side. Will show.

Yes, the only chimney is the shroud. Since then l made a second one on top to keep water off. To tell the truth, only negative thing so far is its messyer to work with. Since it hasnt got real chimneys the smoke is at eye level and l still smell like ham :smile:


How many hours can you and Edvardo play together? I’ve never had such a big friend. His one third size cousin is about all the friend I can visit with and we keep those visits short.


With kiln charcoal production, I always regret this huge waste of energy by burning ot just venting the gas off.
But when production reaches the scale of Kursk kiln, useful capture of the gas may create more trouble than good. Cooling, separation, processing, usage/sale.
Couldn’t be there any small scale semi-continous process which could utilize this excess heat?


Adding on to the shroud upwards and connecting the two side shrouds and putting one or two chimneys on it that both sides vents through is only straight forward metal work an would create more draft. Then adding a layer of insulation and finishing off with a layer of metal roofing lengthwise so the curve can be followed.
I am sure that you already thought of this which means there probably is a reason that you didn’t do this.
Is it only the smoke that is messier?
On the other hand, who doesn’t love the smell of newly smoked ham :smiley:

Edvardo can’t play with the Kursk too long, Kursk plays too loud and the ringing in the ears in unbearable after a while. You could see Edvardo lying down on the ground resting. :joy:


Tom, he is the kind of friend that likes to stick around when he visits :smile: He helps me wedge split the tough logs for Kursk food. I avoid them whenever l can but sometimes some nasty knoted wood gets mixed in.
But its not the weight thats the problem, if you look closely you might see that the handle is a 2" steel pipe. I got fed up with broken wooden handles, splinters knicking them off slowly… so l welded a steel one on. Same on my pick. Works great, untill your wrist gets twice the size, red and feels like it has sand inside (tendonitis). Dont ask how l know… but that was after probably a week of work when l dug out our spring. An occasional workout shakes the bones a bit and thats it.

Kamil, best use l can think of is to have more kilns in series, so that when one reaches the liftoff stage and produces more gas thain it needs, the gas heats up the next kiln. A lot of fuel gets used up to start the thing… its just junk like twigs and branches, punky deadfall… but still.
Wood vinegar and tar, thats a topic for a nother report, l have discobered some interesting things indeed!

Johan, great minds think alike :wink: exactly what you described is alredy installed. Not seen on the pics. I rolled out two oil barrels and threw them over, 2 holes on the top.
Problem is l havent yet sealed the seams, and it mostly smokes here. A bit of mineral wool and concreete over it shuld do it. I did however notice too much draft tends to pull too much air in the burn space, and the heat exits too fast so l need to find a good balance between draft and heat sticking around for enaugh time.

This kiln operates at a much higher pressure. Not sure why, but it sure produces a lot of gas. At this pressure, every tiny leak turns in to a smoky messy cloud of tary smoke, the white brownish kind… sticcks around for days…
Ha, not sure what you ment by it ringing but its spot on. The previous Kursk was silent, had no gas nozzles. This one sounds like a jet engine :smile:


When I use a hammer with a wooden handle it makes one of my fingers hurt, but that doesn’t happen with this hammer. I think the vibration is much less.


I cherish a good wooden handle, craftsman grade well fitted but here is a selection of hammers I keep in the service truck. Tire hammer the head is a slip fit like a pick and easily replaced, brass hammer fiberglass handle not a big fan but they are very price to get a full brass sledge so is what it is. But notice stubby there, 12lb. Many a broken handle to cut down handle for underneath a truck work to now a mack dump truck torque arm handle solid 1" steel. Ain’t never gonna break that one! Though it will blow your back out swinging it all day changing springs pins and bushings as I have found out multiple times now…


Perhaps butterfly valves in the chimneys?

Is this in the startup mode or in the self-going mode?
I am guessing in self going mode and I’m thinking that either your gaspipes to the furnace are too small or that you have too big openings on the furnace so you don’t get enough ’pull’ on the kiln from the chimneys.
Perhaps both problems will be better with doors with adjustable openings in them on the furnace openings.

We like reports :wink: :smile:

I have a few of those metal handles too and as Rindert says, it is the vibrations. Not a fan of those vibrations you get when you put some mucles to use with it.


Rindert, fiberglass?

Johan, perhaps. This is still the testing phase and a lot of things need ironing out.

Correct, the point where the heating is self sustaining l call liftoff. But if you are not carefull, the reaction gets to what l call supernova. A runaway reaction, too much heat, makes too much gas, makes too much heat… and the whole thing melts :smile: its what has to be avoided. So, the gas nozzles have to be the right to not let too much gas in, and the rest of the gas vented, condensed to tar or burned outside. Previous build had a small burn space and too much gas literaly flooded it, lowering the temperature due to not enaugh air thus cooling down the reaction, it was self governing. This one might get in to supernova if all the gas is let to burn in the big fire zone.
Long answer to why there is pressure, sorry :smile: l talk too much…


Aha, I have always thought all the gasses were burnt off in the furnace but that is apparantly not the case. Is it experience telling you how to size the nozzles or is there calculations for it? Or just winging it? (Which is also experience in my book)
So this is how and why the wood vinegar and tar is harvested in a side flow, I always thought that doing that calls for more external heat but it isn’t.

And no, you don’t talk too much or give too long answers. If anyone, it would be me.


Like l sayd, the former design didnt even have nozzles, too much gas flooded out the air, regulating the temp.

It all comes down to design l guess… certainly there is no one size fits all…


I think it is probably fiberglass inside. I bought it at Harbor Freight Tools, the cheapest tools out there.


impressive, your kiln, developped through observation and experience!


Very nice job, it kinda resemble the space shuttle!!:slightly_smiling_face:


Best liftoff so far! Slowly lm geting familiar with the new kiln.

It came dangerpusly close to the supernova state, so l loosened the top lid to vent some gas.
What is interesting is once the wood starts to carbosise, things proceed extremely fast. A true liftoff. Starting with green wood, it takes about a day of smoldering to draw the moisture out. Here temps are below 100c. Then, heating to pirolisis temps. From steam to flamable gas it gets in about 15min, then an hour and a half of pure hell, and its done. No matter the size of the kiln l have noticed, the procedure and timing is about the same. But when half a cord of wood is offgasing is a sight… neighboir came to watch as he heard it roaring from his home!


When its time to transition between the drying and the pirolisis phase, usualy l let a bit of air in to boost the temps fast. Well, with this size, natural draft isnt enaugh. Lickly there is a small diesel near by, pumping lots of air trugh the exhaust when idling. A bit of venturi effect and the doors of hell open…


Kristijan ever since you started using that tank, I’ve been keeping an eye out for one.


Thank you, Really cool videos. :grinning: what did your neighbour think?

I am guessing you keep track of the temperatures in the kiln, do you try to keep it around 450-500C after liftoff until it is done or do you go even higher?