Help me understand a wood carburetor

General Discussion
#1

As you can see, I understand very little of what is happening, I hope you help me.
The nozzles.

  1. Smaller nozzles increase penetration and increase heat, but increase resistance to airflow? Truth
  2. The oxidation of the carbon provides heat that oxidation the wood above the nozzles? (ash?) Truth
  3. Upward-facing nozzles provide increased heat in the wood container and earlier oxidation of the wood?
  4. Oxidation of carbon emits water, gases,air,ash and tar? Truth
  5. Water, gases and tar are converted in the glowing carbon layer under the nozzles into combustible gases? (ash?) Truth
  6. The conversion reduce the heat? Truth
  7. To maintain the heat and change the gas flow, we make a restriction, smaller restriction increases the heat? (or increases the mixture of gases (cracking of tar gases?) Truth
  8. Does the distance between the constriction and the nozzles affect the heat?
  9. Smaller distance between constriction and nozzles increases the heat?
    Edit
    10.If we increase the heat of the air through the nozzles, does the rate of conversion of the gases increase? Truth
  10. Increased heat allows us to increase the distance between restriction and nozzles, more carbon to the conversion of gases while retaining heat?
  11. If we increase the heat, do the nozzles have to be bigger to maintain the oxygen content?
  12. If the gas passes through too cold coal, is it converted to CO2 again?
    Edit numbers.
    Edit Truth
#2

Good Morning JanA.
Our children here want snow. We’ve had no snow here yet this year. They saw your Volvo stuck picture tell me to ask you (Santa) to send them some of your snow now. To please share.

Jan, you have asked 13 questions.
It is difficult to respond trying to figure out what part of the wood gasification beast has you stalled.

I can maybe help on two of the concerns you have expressed.

You ask ASH twice. Ash is the minerals that the tree has taken up from the soil and built into it’s cell walls.
Once we burn away the H, C, and O chains then the ash remains. WE do not create this ash by gasification. Only free it up exposed.
And it must be removed from the fuel chunks/chips surfaced to expose new active surfaces.

Heat and temperature. Think of Heat as a volume. Think of temperature as a height level. Take existing heat and concentrate it; will raise the molecular temperature. And that molecules then excited activity.
In our gasifers Heat is only made in the oxidization areas across, and just below, and just above the air nozzles.
Then that is the only heat made we should have to work with for all other processes.
And heated gasses love to rise UP. It takes extra energy to force them to flow downward to do the work we want in the charcoal area.

My hope is others will fill in more full system details. We each view the gasification beast a little differently.
Regards
Steve Unruh

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#3

Like breathing through a straw.

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#4

I imagine the gasification of wood as a chemical process of decomposing wood into basic elements or their compounds, which takes place at the highest possible temperature. Given the composition of wood C -55%, O - 44%, H - 5% with minimal water and minimal heat loss in the gasifier, I expect the process to proceed with very little fresh air, in this way apricot gas should also be energy

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#5

I have many of the same questions Jan. Whatever understanding I have of these processes comes from operating a hobby forge and working in Steel mills. In both these the key is oxygen. In the forge you form a superheated area by blowing air with it’s oxygen into the center of a carbon fuel. Coal fired forge. but the fuel in that area is not coal. It’s coke formed from the coal at the periphery of the main heat. It’s a constant task to move the coke into the core of the fire and push more coal to the edge to be purified. Coal fired steel production is pretty much the same. Coal is cooked to release impurities in a coking process and then fed into the furnaces as the fuel but blasts of oxygen are required to raise the temps in the furnace above the melting threshhold of the pig iron raw material. There fore I assumed that the nozzles in a gasifier served both to accelerate combustion by drawing the oxygen out of the incoming air but also need to be sized to some velocity to act as a blast effect into the fuel. Now I’m anxious to learn the truth from our experts.

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#6

What does restriction really do, and the length between nozzles and restriction?

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#7

Hi Jan, in gasification it takes time for all of the prosses to take place so that all the tars are all burn up and changed to gases that are good this takes lots and lots of high heat.
To do this we need time. Air coming out the nozzles going to the restriction plate opening needs length or distance which is also takes time to get to the restriction opening. At the opening the now gases speed up that causes more heat more reaction. After this point it opens up the gases speeds slow down and start to cool. At engine idle this opening makes sure the tars are burned up and converted to good gases.
The charcoal below the opening is your charcoal reserves. So when your are going at full throttle down the road this charcoal makes sure every bit of oxygen is used up.
Also at this full throttle speed your hot lobe in the firetube moves down to the reduction opening and reduction zone. They both work together with the the charcoal reserves and the gas. It takes time, length or distance to do this. It is not all happening at once. I picture it as a continues flowing reaction in the gasifer to the grate or a grateless charcoal pile.
Bob

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#8

So the heat increases if the restriction is small?
Because of what Steve says, crowding?

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#9

Yes and everything must pass through that opening. If the gases can go out a different way you might have a problem when you are at engine idling. Because not everything is passing through the reduction opening. This is why I like to seal my reduction plate up with ash only, when it get hot and settles in, it seals and gets hard. It also give protection to the metals.
Bob

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#10

Thanks everyone for the help, I have some questions left, does anyone have any answers to these?

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#12

Now here is the easy read, "Except by . . . " hit your system with a big hammer called Heat.
Keep hitting it Heat harder, and harder. And never stop Heat hammering it.
And then you can more or less ignore all of this other stuff.
Replacing out and thickening material areas that are Heat damaged.
Yes. The Stalin way. “Quantity assumes a Quality of it’s own given enough quantity applied.”
S.U.

#13

I looked for device for specificly burning tar . I was wondering at what temperture it operated . I also found at what pressure it operated . I leave it to you if any of this is relevent .

DESCRIPTION OF THE INVENTION
The present invention involves a novel burner and the process for the manufacture of gas mixtures rich in hydrogen and carbon-monoxide, such as synthesis gas, fuel gas, and reducing gas, by the partial oxidation of a liquid phase slurry of solid carbonaceous fuel with a free-oxygen containing gas such as air, oxygen-enriched air or substantially pure oxygen. The product gas mixture is produced in the reaction zone of a noncatalytic, refractory-lined, free-flow partial oxidation gas generator, such as described in coassigned U.S. Pat. No. 2,809,104 issued to Dale M. Strasser et al at a temperature in the range of about 1700° to 3500° F. and a pressure in the range of about 1 to 300 atmospheres, such as about 5 to 100 atmospheres.

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#14

Steel is born of heat. Heat kills steel. Exactly why I don’t understand why sacrificial sleeves are not the answer. Even in a WK firetube the heat sinks can be welded to the sleeve. I’m not sure about the latest generation but the older ones like mine. Drop it in. Hit it with that hammer as hard as you can and swap it out when it cries uncle.

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#15

Ahh . . . TomH
Best you review all of the last three years of WK builds on the Premium side. ALL with sacrificial plates now.
Ha! You were right.
S.U.

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#16

No. That never happens.

#17

Hi Tone
23.1.2021
~60% of the delivered cold gas is originally atmospheric air… With all the nitrogen…
Max

#18

Relevant quotes from the “Merits of gasifiers” topic to your questions:
“Right, and we’re back to where we’ve been so many times before :smile: Vehicle gasification process can’t be properly examined because it works so differently depending on load” Jan-Ola Olsson

" . . .I agree with you saying that tars MUST oxidize in the upper part of the gasifier, to give clean gas. At least the majority."
“from the nozzles down the heat starts to fall so in order to keep the gasses flowing at the same speed, the diameter needs to be gradually lower(ed), hence the restriction. But it comes at a price of more drag, and the restriction heat suffering; plus potential heat losses.” Kristijan Leitinger

S.U.

#19

I thought it was very thoughtful what you wrote Steve before you removed it.
If I understand correctly, the longer the distance between the nozzles and the restriction, the colder the gas before it is mixed in the restriction and the easier it is for tar to escape?
At the same time, a larger amount of carbon can convert the gas.

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#20

Jan I am getting a lot of Hate for talking too much here on the DOW.
Anything I’ve come to understand, and working use; if it is true; and gasfication useable: others will have seen, and discovered too.
Proofed by my peers.
So I will now be doing a lot of positive quoting here-on-in.

Best Regards on your wood-for-power. I have all confidence you will get there too.
Steve Unruh

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#21

I think we are many who appreciate what you write, it makes me think.
I really appreciate the information I get from all of you who have been doing this for a while.

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