[Stoves] Particles and particle types (was Charcoal Making Stove)

[AJH]

On Tue, 24 Oct 2006 18:39:29 -0500, Tami Bond wrote:

>
>If you like you can call these things 'aerosols' which means a solid or 
>liquid particle suspended in a gas.

Yes, sols are interesting things because they have weak forces that
both attract and repel the constituents and it's the regularity with
which they do that that affects the way they interact with light.
Hence the sooty particles in woodsmoke appear blue on reflection but
yellow with transmitted light.

>
>I think of 3 kinds of particles
>1. ash (the solid fireflies) which are so large that they are only 
>lofted when there is a lot of velocity (fans or buoyancy).

Are you confident these are always large? It's the possibilities of
forming small silicacious particles that concerns me.

>
>You can combust unburned fuel by keeping it *really* hot and mixing 
>well. Time, temperature, turbulence.
>Harder to get rid of black smoke below ~1200 C; it just doesn't oxidize 
>fast enough. There is combustion literature on this topic.
>Dilution quenches everything. If you're down to 500 C, probably won't do 
>much of anything, so you have to get it at the flame front.

I find that flue exit temperatures of 700C are generally high enough
to get visibly clean effluent if there is enough excess air when
burning wet wood, mind this is sampled with a K type thermocouple
which are notorious for under reading in an environment where they see
a lower temperature surface to radiate heat to. If there is
insufficient air then there will always be soot in the exhaust, just
like running a car with the choke on.

AJH