Thanks, Kristijan. I missed that the question was about smoldering charcoal, not smoldering in general.
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From the discussion of pyrolisys in the context of wood-based-gasifiers I understand that two processes occur in woodgas-reactors: incineration and pyrolisys. But, only pyrolysis produces the gaseous fuel that we want. Combustion/Incineration is required to generate heart for the pyrolisys reaction.
Therefore, oxygen-concentration in the reactor is the fulcrum between pyrolysis and incineration, because incineration AKA combustion AKA buring is oxidative and pyrolisys in not. (Please correct me if needed)
But, what if we could separate the processes of incineration and pyrolisys with an expiremental apparatus?
I am in contract with a YouTube Pyrolysis Reactor Designer and Operator: NatureJab ( https://www.naturejab.com/ ) His design uses magnetron heating elements (from microwave) to drive the pyrolysis reaction on plastic waste. Because plastic is petroleum byproduct, his effort focuses on recovering a liquid-fuel not unlike gasoline.
However, he has agreed to put wood-chips in his reactor as either a partial or full-load as an expirement.
From such an expirement, what would you be most interested in?
What might we determine? And, what part of the reaction is not well understood?
I’m looking for input from wood-gassers, has anyone put plastic in their reactor?
Thank You For Your Consideration and Happy New Year!
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If you take a look at the back of HWWT, the reports from Auburn show they did do a test of mixed wood and plastic. It’s also here in the free library:
You’ll still need wood to maintain a char bed and not all plastics will play nice. I’d stick to HDPE and LDPE aka milk jugs, garbage bags, soda bottles and caps. I do a little bit of 3D printing and when I get my WK done I’ll probably toss in my failed prints, especially my PLA since they’re plant based anyhow.
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Ben Peterson was working in this area. I can’'t find anything related right now but I’m not that good on a computer. I"m sure someone here can help. My area of interest is self sufficiency. I never saw a way of coming up with enough plastic to make it feasible to produce useable amounts of fuel.
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Tom, unless you live next door to a garbage dump / landfill! 
Wood is the freedom fuel. 
(In my opinion…)
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KVL’s work from a long time ago; charcoal gasifier:
Scroll up for a picture of the gasifier.
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Exactly, and like Mike said Wood is the freedom fuel.
I see it as a “well, if it works and I have some then cool” kind of attitude to adding stuff other than wood to a gasifier. I think Edmundo Ramos also has added plastic with his charcoal but don’t quote me on that.
I’m not a soda drinker anymore so I don’t exactly have a steady supply of bottles, and you’d probably want to shred it so that’s just more work. If I’m out and about I’d maybe toss a bottle or two in to not litter. Make sure you take the caps off or you might hear it go boom in the hopper.
I think HDPE is more useful as something to melt down and re-use since you can melt it in an old toaster oven. I’ve seen neat stuff made out of milk jugs and caps, like knife handle scales.
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Hi JoeSPA
one of the overlooked factors in conversion from solid fuels to gaseous fuels is the cells structures that grown woods have. Far more complex going on than just thermal-chemically breaking to elemental oxygen, hydrogen and carbons. Then recombining into fuel use chains.
I’d thought of pointing this out on @Kellyian “Gasifier for running on MDF”.
Observe the glowing cells layered stacks in the gasses in-out gasses exchanging going on in the lower hot burning charcoals:
Click on the picture and expand out to really see this.
At certain conversion rates you can see a pulsation cycling “breathing” occurring.
Also see the glass edges now smoked up door glass.
Made by a few pieces of OSB (oriented strand board). It at least has some remains grain structure in the shaved, been compressed woods strands. And a much lower percentage ratio of homogenous resin binder glues that any HDF or MDF furniture materials.
The proof of my beliefs is burning for fuel actual wood plywood scraps; versus raw wood split and chunks; versus even OSB/HDF/MDF. Plywood is ok; almost complete grain layers structure left in the thick sheets layers. Not so bad.
The others are pita sooting, blackening, all insides coating.
To burn for heat or fuels cleanly, completely fossil coal; homogenous plastics and resins requires they be particularized / shredded to make greater surface reactive edges as they are non-porous. And still then needing forced air to add enough extra oxygen to even begin to chemically balance out their excessive carbons in the plasticizer resins glues.
Still . . . using any wastes as fuels means you are Urban dependent on those wastes being generated.
You convert yourself to being a cockroach solution for others excesses and lazinesses to generate your consumable inputs.
Cockroaches, and other wastes converters like maggots and worms never get Hero awards. Tolerated at best. Always shunned and bad-mouthed. Aggressively killed off at worst.
Grow your own trees and brush and then you are fuel input Independent. Only way to be truly Free.
Steve Unruh
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I, and I believe that most users of this forum, have the goal of obtaining quality gas from wood, suitable for use in an internal combustion engine. One of the processes that occurs in a gasifier is also the so-called pyrolysis, if I type the word “pyrolysis” into an online search engine, the first result is the following text:
“gasification and thermal decomposition of wood (pyrolysis): at higher temperatures, gases (oxygen, hydrogen) are first released from the wood, followed by the thermal decomposition of the wood (cellulose, lignin,…) into a gaseous state. Pyrolysis is an endothermic process (uses energy), while combustion is an exothermic process (releases energy)”
If you look at the gasifier sketches in more detail, you can see that the air inlet nozzles are placed low in the area where the charcoal is mainly located, where the oxidation of the charcoal mainly takes place, which glows white in this way and thus creates the conditions for the conversion of pyrolysis gases. At the same time, part of this radiation spreads upwards and heats the wood above this area. This expansion and also the direct oxidation of hydrogen and oxygen, which is released from the wood, create conditions for the expansion of a large amount of new gases, which in turn relatively raises the pressure in the gasifier, which automatically reduces the flow of fresh air,…
If we think like this, we cannot draw a line in our method of gasifying wood that would determine the limit above which only pyrolysis would take place without oxidation and also the release of carbon atoms, everything above is intertwined.
Mr. Steve recently mentioned the simplicity of the “Joni” gasifier, where our friend uses a very shallow area with charcoal and states, as far as I understand, that all three processes (pyrolysis, oxidation and reduction of gases) take place directly in a narrow area, this is also proven in his contributions. Well, Mr. Wayne (and I) use a large supply of charcoal in his hot tube, which provides the ability to run for long periods at low load, or even sudden full loads, without fear of running out of charcoal for reduction.
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Hi Joe.
Its way more complex. But most of all, the gas we use to power our engines is not pyrolisis gas. In fact, we struggle as hard as we can to avoyd it as its full of tar. Thats the tarry, smelly sticky hopper gas. Only after it has passed trugh a hot bed of carbon it transforms in to clean useable gas.
Tom, same here about the plastic. But l live next to a cemetery and in our country we got a nasty habbit of lighting big parafin candles in plastic covers over the graves. Looks nice but horrible for the enviroment… well, about a fifth of the wax ends up in the bin and the huge bin does fill up fast. While the plastic cover is PVC its useless, but the parafin is pure and l am figuring out how to use it for a long time now.
Occasionaly l see a liquid parafin candle with like a pint of oil still in, thats basicly the best diesel you can get. But the majority is solid wax. Was thinking to melt it and impregnate charcoal with it for a gasifier. Shuld make wery potent gas, needs testing
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Yes, this can be observed by watching the vacuum ratio between rails and hopper during a hard accelleration. Starting from a normal 3:1 ratio, I sometimes find it increasing to 6:1 when pushing things hard for a while.
One famous author once said - “there are so many variables…”
I don’t recall him mentioning this fenomena, but that may be due to his superior hopper condensing ability, which will take care of most of the excess steam created, even during a hard pull.
Another variable is the increasing heat of the gasses passing the restriction. They will expand and take up more room, which will also contribute to the increased vacuum ratio. Very hard to tell which variables are affecting things the most.
I remember Kristijan once reporting - I think it was one of his waggon box gasifiers - when he let go of the pedal down to idle, smoke started to back out his air inlet. I’ve never experienced that much positive pressure, but my air-mix can be thrown off some. After idling for a while and things cool down, I need to richen the air-mix back up to keep the engine from stalling.
Just thinking out loud here - confirming your statements.
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Hi Jo, smoke coming out the primary air inlet happens me all the time, more after pulling hard.
I use it a lot for tailgaters, it’s interesting to see how much smoke-smell they stand.
The old blue volvo had a very tight check-valve flap in the primary inlet, and not much resistance through the bad filter lead to, when down to idle, the positive pressure filled the secondary piping backwards, pushing the air out. This leading to stall, after some seconds, or, when taking of again. Therefore i like using double, in series secondary air valves, one coupled with throttle.
This phenomena is mostly a Imbert-thing, i believe, the WKs big char, and heat reserve would deal with this, and “even out” the fluctuations.
What do you think?
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I thought you used the longest finger on your left hand for that. 
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Well, as I mentioned before - there are so many factors involved. Funny enough I have more of the varying pressure (air-mix) sympthomes on the huge WK-inspired Volvo gasifier. The Mazda truck has a smaller Imbert-inspired charbed, but with less sympthomes 
Still, I’ve never had smoke backing out on either of them unless I shut down the engines. But then again - different engines and different setups. On the truck I have huge 120 liter filter barrel. It may even out both pressure differences and gas quality some.
I see Don just chimed in. I think with enough smoke the finger isn’t necessary 
I’ve had hopper puffs in situations like that (white smoke) and even some intake events (blue smoke). The proplem is you cant rely on them happining at the right time
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Hehe, that is only when they get enough of the smoke, and passes me. But only if the honk, and behaves as $ssh#les. 
But i am very nice in traffic mostly, sometimes im ready to give a real close tailgater and honker the “evil eye”, just to be surprised when they pass me, it’s just because they want to film the wood powered car, and wawing, giving thumbs up 
Sometimes it’s a benefit to live in a country where some knows what woodgas is…
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Something i know affects this, is i mostly drive on not perfectly dry wood, as im a little short on space, the amount of moisture releasing could be enormous.
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I have already written that shortly after I started using wood gas in my tractor, I noticed that thick smoke started coming out of the air inlet every time I went down a slope or took off the gas after a heavy load. , so I installed a non-return valve , well , I still check the effect of the overpressure several times by opening the chimney , where smoke is visible. Even if there is no additional air to maintain the layer of glowing charcoal (for a short time), there is no fear that the temperature in the hot part would drop significantly, since a lot of oxygen is released during pyrolysis, the overpressure of which pushes it down into the glowing charcoal. Intensive cooling of the upper part of the gasifier, which also causes intensive condensation of catean gases and water vapor, which means a decrease in pressure inside and thus the constant entry of fresh air into the process, if we take this to the extreme, the gasifier becomes a heater just like a central heating boiler. We want to get as much good gas as possible for the engine to operate, so a compromise is needed in the balance between the intensity of condensation and the humidity of the gas at the outlet of the gasifier.
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Indeed, l had problems with any stelth gasifier build. Small super insulated hopper meant that soon the whole hopper went in to pyrolisis mode. This produced potent gas when driving but idle was impossible.
Here l have to disagree Tone. This is a huge problem and it absolutely will cool down the charcoal lair. You may not notice it that much because your gasifier is big and has a big mass of charcoal but in my small stelth gasifiers it was like someone poured water in the gasifier as soon as l went to idle. And indeed thats exactly what happens. Yes, oxigen does come as a product of pyrolisis but unfortunaly mainly as water. This steam will react with hot carbon to make extremely potent gas, but its also extremely endothermic and with no aditional supply of energy (no fresh air intake) the resault is a dead gasifier.
Only practical way to get around this was a wery high idle, in the 2000rpm range. I tryed air cooling the hopper via powerfull fan and this complicated things alot. Wet charcoal is the way to go for such project as it does not show any of this effect
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Kristjan, such discussions are very useful, it is good to have a discussion about the details that go into turning wood into gas. Understanding these processes is essential so that you can build a gasifier adapted to this task.
Now, when we talk only about pyrolysis, I can highlight some characteristics:
-wood consists of carbon, hydrogen and oxygen atoms bound to each other in various bonds
-when we heat the wood, it starts to dry and at about 150 °C all the moisture evaporates from the wood
-when we heat the wood to 200°C - 250°C it starts to smoke, which means that some of the bonds between the atoms in the wood structure start to break
-if we know the process of cooking charcoal, where we get only carbon from the wood, I can say that first mainly hydrogen and oxygen atoms start to be released, Kristjan calls this “chemically bound water”. Now we have come to the key point where opinions differ, I think that the oxygen and hydrogen atoms are released separately, but if the conditions are right (high enough temperature…above 500°C), they can also immediately combine into H2O, which means combustion and additional high heat, which also tears apart the carbon atoms and forms tar gases.
So what happens when we have a layer of glowing charcoal below, and very dried or torrefied wood above? My opinion and experience show that here, for quite some time, very high quality gas is produced without additional air. The condition is the airtight closure of the non-return valve on the air inlet, which allows the pressure to rise throughout the entire gasifier system, including the filter and cooler. It is also interesting that the condensation of excess steam becomes more intense at higher pressure (another automatic phenomenon that has a positive effect on the operation of the gasifier). However, the engine requires a good gas mixer that is not too bothered by this fluctuation in gas pressure.
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What the four of you ToneS, KristijanL, JO, and GoranK are describing are actual working conditions wood gasifiers.
Practical guys putting a system to practical daily usage.
That means from a cold condition starting up; to a stabilized continious operation.
And as an organic solid wood fueled system, HOW from the previous full operations running state-of-conditions, the gasifer system was left by the operator; determines just how difficult, and long, of tars making, that next from cold starting up to stabilized will be.
The step-by-step; must-understand down to the molecular level approaches to understanding, will be L-o-n-g, t-e-d-i-o-u-s and lose the patience of most all of your supporters.
What works better is to make something work in any fashion. Then improve, improve, improve on that beginnings.
Then the fellow able to do that; has the difficulty of separating out what was actual system successes and failures/limitations; versus also growing/learning capabilities operator enabling efforts.
Because a good operator can make blue flare gas out of a long piece of metal pipe.
Yeah. A short show-off stunt, yeah. Frankly what most all only have the patience for. YouTube moments. Then they skip/flitter off to another feat of interest. Frankly most people are butterflys in this modern enabled world.
Rare, rare, will be the individual to months after months grinding out, true able-to-work, working systems, accepting that the working operator will be the key to it too. Too many will then waste much efforts, time, and resources digitizing it. Automating it. Dehumanizing it. And call that progress.
Steve Unruh
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