[Stoves] "exothermic" is still a kind of mystery for me

[Ronald Hongsermeier]

do a google search on : pyrolysis mass flow analysis  and see if that 
helps you. i think it may well do so if you will spend some time reading.

regards,
ronald von den husten

On 23.04.2013 14:21, scda2 at t-online.de wrote:
>
> Literature:
>
> When the wood is dry and heated to around 280°C, it begins to 
> spontaneously break down to produce charcoal plus water vapor, 
> methanol, acetic acid and more complex chemicals, chiefly in the form 
> of tars and non-condensable gas consisting mainly of hydrogen, carbon 
> monoxide and carbon dioxide. Air is admitted to the carbonizing kiln 
> or pit to allow some wood to be burned and the nitrogen from this air 
> will also be present in the gas. The oxygen of the air is used up in 
> burning part of the wood charged.The spontaneous breakdown or 
> carbonization of the wood above a temperature of 280°C liberates 
> energy and hence this reaction is said to be *exothermic*. This 
> process of spontaneous breakdown or carbonization continues until only 
> the carbonized residue called charcoal remains. Unless further 
> external heat is provided, the process stops and the temperature 
> reaches a maximum of about 400°C.
>
>
> ADAM:
>
> Comment: "exothermic" is still *a kind of mystery for me, *because I 
> often realized that If the wood chamber of a retort already heats up 
> to ~300°C -- still a lot of heat Is needed from *outside* to push 
> gasification.
>
> I am really tempted to make a laboratory experiment. Place a piece of 
> oven dry wood in a small container, and place it in in electric oven 
> by 500°C., record the temperature inside the small container wood, 
> ideally the temperature should jump up more quickly above 280°C, 
> because of additional "exothermic" heat supplied from "inside the 
> wood-charcoal piece?
> *But I don't recall to have seen such a jump in a plotted graph?Also 
> anyone has an idea about that"amount" of that expected "exothermic" 
> heat??*
>
> THANKS Chris
>
>
>
>
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