Thierry, this is a excelent idea!
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Beware of excellent ideas that add fabrications complexity. Add mainteneces points. Add failure points.
Engine heats inputs are better applied by reducing down the raw fuel wood moisture and pre-warming the raw wood just before adding into the hopper. Then the gasifier system can be single wall simple, not condensating.
To better heat boost the tar ring section Ben Petersons’ original Woodie model gasifier and then his later book system route the hot produced gasses first past a simple inlet air loop. Then around the tar ring zone; as an “pyrolysis accelerator” before exiting the gasifier hearth. Removing some of the heat from the gas and internal slowing it he had to enlarge the the drop out pocket and cleaning out trap.
Tones proposal is to preserve the core reactions heat in a charcoal system by temperature energy wrapping the core with still hot produced gas. Let the hot gas lose the external heat. Not the core reaction area.
Way back Australia Kurt Johanasson did this with his triple shell raw wood gasifier system.
So not a matter of who copied who. They were/are all realizing better uses for all made heat energys will give better overall boosted performances.
Heat energy is only wasted, if you waste it. Do not attempt put it to some useful work.
Max gasman was always saying to stop heating the crows.
S.U.
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Thinking about very high carbon material. I have heard many times that cast iron is very corrosion resistant. It has higher carbon content than any steel. Perhaps cast iron would make durable nozzles.
Rindert
P.S. But of course Silicone Carbide (Hexaloy) would be the ultimate.
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It does have a wery low melting point thugh… and bad thermal conductivity. But the good thing is it culd be cast in any form so thats good. Easy to machine too.
Speaking of wich, l tryed throwing a bit of cast iron in the forge a while back and l was surprised how easy it melts. Im thinking of giveing casting a try someday. I love cast iron cookwere but here you can only buy enamel coated ones wich are crap, and they cost a kidney…
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I realy like the charcoal cooling method. Will use for sure.
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If you do it maybe you can make money that way. It used to be a “cottage industry”, meaning one person could do it in a shed behind the house. The hard part is making patterns.
In modern times most patterns are made by CNC. So then, if you have a CNC machine and really know about the metal casting industry in your area you can maybe make a living as a pattern maker. But you have to be very good, because now people expect everything to look perfect.
Rindert
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In the topic about the tractor, we nicely developed the thinking about the production of caloric wood gas, Goran and Bob state that when the fuel starts to run out, a very strong gas appears, how would one explain this? Obviously, the temperature in the hot zone with charcoal rises a lot, thus the steam and pyrolysis gases are completely decomposed and strong gas is produced, and in all probability the entry of fresh air is also minimal, because the expansion of gases at elevated temperature is large. I notice this situation with my gasifier when I put more load on the tractor for a while… What did I do differently in the gasifier than what is done at WK? The biggest difference is in the size of the air nozzles, and I think this is essential. If we make an experiment and blow compressed air into the embers through a small hole, we can see that this method ignites the charcoal much more than a gentle breeze, and I also believe that in the first case, much less air is introduced. I think that the narrow and fast jet of air also drags and swirls the pyrolysis gases, which penetrate deep between the glowing coals and thus the conversion of gases takes place at a high temperature. I will mention the lower nozzle again, where the negative pressure is the deepest and thus the air velocity is the highest, there is an area of fine coal, coal dust and ash that collapses from above, probably a “bubble” of coal plasma is formed here, which transforms the remaining superheated steam into flammable gas. Some time ago, we said that this air supply can be done with a valve from the engine and a ring from the bearing, well, it would make sense to cut notches in the ring from the bearing, similar to how a gas burner is made on a stove, it is possible to make the notches at a slight angle, in order for gas circulation to occur.
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Yes Tone, I see that the Imbert design uses a much smaller nozzle holes which causes a higher velocities of air blasting into the firetube area and have a different shape firetube, and lower velocities air blasting in the firetube in a WK Gasifier with much larger nozzle holes. The common things they both have is time, frequency of light and sound, heat or temperature, vaccum, air, moisture in the fuel but not the type of wood fuel, hard, soft, mixed or moisture content. You said at the end of the fuel run when the fuel was fully pyrolysis and moisture was removed from the wood that is now Charcoal, thus event happens. After pulling hard on your tracker engine going up hill. In my experience it is a high vacuum pull maybe caused by the charbed not necessary a hard pull or load on the engine, but it can be from going up hill.
So narrowing down, it sounds like at this point the wood fueled gasifier does a conversion changing over and becomes more like a Charcoal Gasifier in its operation. We know Charcoal gasifiers are lacking water/moisture so we add it. A wood gasifier has to much so we try to remove it. We also know this is a balancing act of being way to hot or to cold in making good gases out of a gasifier, what ever design type we are using. It seems there is this almost perfect zone to operate in with many variations. We just need to find it and operate in it when we can. Conclusion is if we can build a gasifier that can make and operate in this super good zone for long periods of time that would be the wining combination. You seem to be on the right track with upper/ lower nozzles.
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Tone, with your gasifier, when it is powered by perfectly dried wood, do you produce dry gas? (like the gas from a coal gasifier with a downward flow)
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"The biggest difference is in the size of the air nozzles, and I think this is essential. If we make an experiment and blow compressed air into the embers through a small hole, we can see that this method ignites the charcoal much more than a gentle breeze, and I also believe that in the first case, much less air is introduced. I think that the narrow and fast jet of air also drags and swirls the pyrolysis gases, which penetrate deep between the glowing coals and thus the conversion of gases takes place at a high temperature. "
Do you mean that the air must not only enter at high speed into the gasifier but also through many small holes?
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Bob answered the question perfectly. Charcoal has too litle water, wood too much. Thats why l developed what Bob later baptised as Rocked fuel. Your torrefied wood achives the same thing! The thing is, even wood with 0% moisture (technicly impossible) still has one molecule of water too much per atom of carbon, so either we chemicaly eliminate water (torefication) or add carbon to it (charcoal).
Yes, l have observed and writen about this “supernova” effect a lot in my Mercedes thread. Indeed, once the gasifier gets to a certain temperature, interesting things start to apear. You wuld think that the gasifier wuld go to heater mode, spiting unreduced gas trugh the grate, but not in my experiance. I once tryed flooring it on the highway for a long time. Imagine. A 2.3l engine, with a gasifier l belive 7" in size. Runing on either Rocket fuel or wet charcoal, cant remember, doing over 85mph and still wanting to go higher but the traffic was bad. It just seemed it had limitless gas producing capability!
But! Whem l opened the gasifier next day, instead of a charcoal filled charbed, inside was a ball of slag the size of a large grapefruit 
and the gasifier cracked badly…
So. First of all. To reach those temperatures, raw wood is out of the question. There just is no way, its water moderates heat too well. So torrefied wood or Rocket fuel, or wet char. Mercedes also had a excelent gas heat recovery heatex.
Second, we must ask ourself do we realy want this effect? Deal with slag and half molten gasifier? I dont know…
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I think that it is impossible to get such caloric gas in a charcoal gasifier as from a wood gasifier. For example, when we open the lid on the wood gasifier and brown smoke rises from it, which is created from dried wood, we all know that this is a terribly strong gas, but greasy, full of tar, but when this gas passes the hot zone and is blown by air jets pushed deep into the glowing coals, the gas we want is created. A construction that would enable such operation in a wide area is a challenge for me. I have before my eyes a sentence uttered by my brother Primož, “steam and pyrolysis gases must be pushed into the heart of the action”, so a narrow and fast jet of air would be the right solution, as it moves the extreme heat away from the housing and metals and pushes it there and vortices of pyrolysis gases. In this way, the extreme heat stays in the middle of the hot pipe, where a loose zone is created, here the pieces of coal and hot gases swirl without problems and move downwards, but here the air jets tear them apart and push them aside,… It would be very good if the gasifier would work in overpressure, this would be achieved by blowing air onto the nozzles, the condensation of water vapor would be much more efficient, but there is a great risk of gases coming out, so I am abandoning this idea, but in the future I will try using even smaller air openings
Thierry, lately I’ve been using exclusively air-dried wood that dries in the gasifier, I can say that there is no water leakage from the front of the refrigerator, well, the filter is still a bit damp
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Tone I believe you are on the right track, since Joni came to the same conclusion with his gasifier. High velocity nozzles with a significant length to build a self repairing protective ash layer.
In my WK that I am building I think I may have accidentally jetted my nozzles. The lug nut nozzles I added are 1/2" but before the nozzle are 3/4" holes. May create a Venturi effect. I’ve been wondering if that would be detrimental to the way a WK naturally works.
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Yes Tone.
You re-state one of many reasons to pursue raw wood gasification.
A challenge without a doubt.
Rise to this challenge. For the net energy benefits.
I live in a place of mountains, small plains valleys and the mighty ocean. A place where it annual does rain a lot.
So flowing rivers. Many, many flowing rivers small to mighty.
The WK system is one of the lower Columbia River dams. Not all that high. By retaining and channeling a relatively slow flow; but a massive volume of flow. Flows capable of filling valley plains with deep, deep rich silt. Create wash out deltas into the ocean. Flow volumes harnessed, able to powering whole cities and industries.
The air velocity is king gasifier systems are like one of the upper Columbia River power dams. Up there less flow volumes but falling from higher that flow/velocity churning does easily carry down all fines and silts and erode away first soft, and then hard rocks making fresh minerals available. Dam restrained and channeled makeing useable power too.
There are selected uses and needs for charcoal gasifier systems. But it is offensive to see the energy loss in the charcoal making part of it to me and others. Impossible to justify this except as a narrow needs solution.
A fancy sweet cake to be eaten occasionally.
Much better to daily live on full use soups and stews. Meat pies.
CodyT reminded of Joni who did develop and demonstrate good power from chipped type wood fuels.
There was in the early 2000’s related an account of the modern Finnish woodgas driver who on his very complex W flow pathway hearth had a burn through introducing wood chip pyrolysis gasses directly deep into hot active hearth core.
He was then getting wonderful engine power. He could not explain the why’s of this.
He did then however supposedly intentionally designed to duplicate this.
He held the information close, hoping to patent it and sell to the big power companies I think. Or maybe unwilling to share until he could explain the why of it.
Your concept has been discovered and done previously Tone.
Keep pursuing this.
Best Regards
Steve Unruh
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I have found the size of the holes in the nozzle and how many nozzles to the size of the engine are directly related, the engine’s rpm, that makes vaccum makes the velocities of air being pulled into the firetube through the nozzles. On the other hand same size liter engine the vaccum can very greaty by rmps of the engine. Adding a active charbed of a hot
Lobe high heat will change it more.
Try this some time with a cold firetube. Look at the vaccum measurements above the charbed hopper reading and after the charbed your cooling rail readings driving. Running all the air through the gasifier system to the engine on gasoline or diesel vs. running the same engine with the gasifier operating with a hot active Charcoal bed. The nozzles velocities of air flow are the same moving through with the same rpms right? No. But the vacuum pull readings will be much lower. Why? It is the cold gasifier Charcoal bed. High vaccum or high low velocities are not just the size of the holes or how many you have. It can be your charbed being what we call loose or tight. Lots of variables in a gasifier of different types of design in the firetube. Some with insulation and layers with ash, some designed to pull heat out of the firetube transfering to the in coming air that protects the fire tube metals. The list goes on and on.
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Harder, but not impossible 
charcoal has all the potential to make gas with a consistancy of 50% CO and 50% H2 (water gas), without the danger of tar ruining the sistem like wood does. Geting to that is a nother question… sometimes it happens. Like from all the guys reporting extreme power when low on wood. Or the anecdote l wrote with my Mercedes on the highway. But to put this to everyday use is a nother question…
This water gas is what can be seen as a flame at gasifiers air intake at shutdown, when steam reacts with hot carbon and makes this potent nitrogen free gas. This gas is stupid fast burning, and l dare to say probably shuld be stronger thain petrol.
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I am not sure that it got clear on in the text, I read it a few times and interpreted it different the second time around (which is probably how you meant it) so this is just to make sure for me and other newbies. 
As you all know I don’t have any actual experience yet but the big increase in volume and velocity because of the heated air/gas should cause very different readings.
But this is a smart way to identify if you have bottlenecks in the system, especially if you have many points to read the vacuum by moving the meters to get the vacuum difference between different parts of the gasifier.
If they show on a cold system then also have unnecessary vacuum when running the gasifier as well.
And please tell me if I am wrong so I can learn 
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Very true. A dead cold charbed doesn’t offer much resistance at all. Even whith the gasifier lit I find the vacuum ratio can sometimes double with a long hard pull vs moderate speeds.
In the back of my mind I seem to remember at some point we discussed the fact that air expands about 3 times with a 300C increase (negative pressure not taken into account). Imagine what will happen to the gasses passing the live char.
An interesting experiment would be to somehow compare the woodgas flow exiting the gasifier vs downstream the cooler. Maybe we’re underestimating the tubing size needed for the hot parts.
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That is kind of how I am thinking too, up the hot dimensions to keep the resistance as low as possible
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Somewhere i described my Volvo system, i put on piping like my mentor told me, double cyclones, from them 2x2 1/2" down to one 3" pipe over the back, on the roof down to 2 1/2" pipe down front to the filters, after filters 2" pipe up to engine. No cooler on this, gas around 40°c always up engine (up 50°c hot summer).
He learned me about the gas expansion law, don’t remember now, gas heated from 0° to 275° expands 5 times?
This should help keep gas speed steady along the piping.
On the chevy i just use too big pipes all the way, because there is space, and i had them.
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