metalresearcher
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Wood burns in air at 1900 C ?
Wood has a lot lower combustion energy than gas fuel such as natural gas or propane, because the (very rough) formula is (C6H10O5)n so it is just a
'compound' of water and carbon, so the water does not participate in the reaction. Btw, this 'water' is not the moisture always available in wood.
Propane or natural gas (impure methane), or even coal (impure carbon) do not contain fixed oxygen at all.
Combustion values per unit of mass:
https://en.wikipedia.org/wiki/Heat_of_combustion
So one would expect that wood burns at a much lower temperature. Wood does actually not burn in itself, it has to be lighted by tinder, newspapers,
lighting blocks, or other ignition source. This is because wood has to be decomposed and the resulting flammable gases ignite and provide heat to
decompose more wood. This endothermic decomposition process which lowers temperature, does not exist in coal or gas.
But in flame temperature:
https://en.wikipedia.org/wiki/Adiabatic_flame_temperature
wood (assumed dry seasoned wood, not freshly felled trees) burns as hot as methane or propane in air.
When I look at my woodstove and point my temperature gun to the hottest embers, it ts rarely hotter than 900 C and that is already charred which burns
hotter.
Where are these fugures (1900 C in air) got from ?
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Bert
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Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
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Note these are theoretical, not actual, flame temperatures produced by a flame that loses no heat
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So in the real world, you have all kinds of extra air with plenty of nice cool Nitrogen moving through due to convection, plus radiation, plus
probably other losses that I am not caffeinated enough to think of.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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unionised
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The nitrogen is accounted for, but the other losses are not.
Having said that, even a candle flame gets well over 1000 C so I doubt that a wood fire is as cool as 900
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Bert
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There is rather more air moving through an open wood fire than that which supplies exactly the ammount of O2 needed, and that ammount would be widely
variable by the construction of the fire, wind, size, any artificial draft from a chimney, etc.
The factors are so widely variable, I do not think that the gas through put COULD be accounted for.
[Edited on 10-12-2017 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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unionised
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Adiabatic Flame temperatures are calculated, rather than measured.
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Bert
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Temp measured was in the real world. I assumed he was asking why the IR thermometer was giving him a far lower reading?
You're certainly correct about the calculated temperatures. I may be right about what's going on in his fireplace?
[Edited on 10-12-2017 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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zed
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Burning wood, can get very hot indeed. Force air through it, and you will see the magic.
Here, it appears that rogeryermaw, may be burning wood with a forced air assist, to produce Phosphorus.
https://www.youtube.com/watch?v=mibM4WUx74Q
Need copper? This unit doesn't run on wood, but I suppose it could make as much Phosphorus or Copper, that you might ever need.
https://www.youtube.com/watch?v=W1VF_iVQmM0
[Edited on 11-12-2017 by zed]
[Edited on 11-12-2017 by zed]
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