[Stoves] Inverted top lit updraught

[ajheggie at gmail.com]

On Sunday 15 January 2012 18:09:00 Alex English wrote:
> Andrew,
> Can we melt steel with torrified wood?

Probably and it would be easier the higher the carbon content of the steel 
as the carbide forms a eutectic mixture with the iron which has a lower 
fusion temperature than iron.

Of course you can raise temperature substantially by using an oxidant 
other than air because that removes the nitrogen from the massflow.

What calorific value for the torrefied wood?

A propane:air flame has an adiabatic temperature of ~2000C but I have 
never managed to melt steel with it, oxy-acetylene is good for 3000C and 
easily melts steel.

Whilst I'm fairly confident the peak temperature achievable with a given 
flame is proportional to the mass flow I don't think I can calculate from 
first principles (the sum of energies from bonds broken and bonds made) 
and come to the same results as experiments measure various flames to 
yield.

Worse than that, I don't have access to equipment capable of measuring 
flame temperature and the temperature of the item being heated by it.
>
> I'm trying to follow your thinking on the propane flame, inner/outer
> business. Are your suggesting that the pyrolysis gasses be kept
> separated from the CO from charcoal gasification  in one device like
> the Dasifier and then burn the latter inside the former.

Just speculating along those lines. Consider also that propane burners 
with electrical elements heating the combustion air reach much higher 
temperatures, so the woodgas flame might preheat the furnace and the air 
for the char gasification, so instead of the CO+N2 mix exiting the 
gasifier at 850C...


>
> The other Das trick to elevating the useful temperature is the intense
> mixing he generates with his compressor induced flows, thereby
> maximizing the heat flux  in a small volume.

Yes but isn't this more to do with losses from the furnace, definitely 
keeping the smallest flame ( which requires mixing and turbulence to 
complete the reaction in the mallest volume) keeps all the heat 
concentrated.

We seem to have drifted somewhat from DD verses IDD for a clean flame.

AJH