Pellet Stove Principles... (also Junto?)

[Reedtb2@cs.com]

Dear Dean, Paul and Aul:

"Starting a fire above a fire" is certainly a good idea, but will require more air and more control, depending on the nature of the first fire.  

I take as my text the wood pellet stove.  Dry wood pellets are supplied to form a layer of pellets controlled to no more than 3 pellets thick.  The upper pellets are rapidly heated by the rising CO generated by the charcoal which burns on a grate in an updraft of air, and much of the volatiles are burned in remaining excess air.

Most of the air is consumed by the bottom layer of charcoal formed by pyrolysis of the top two layers, but there is still sufficient unburned air to finally burn any smoke and volatiles not burned during the flaming pyrolysis of the upper layers.  (Air/Fuel ratio for charcoal combustion = 12/1; for biomass = 6/1; for pyrolysis = 1/1.) 

If all this is done properly there is VERY low emissions and LOW excess air, and still efficient heat transfer. 

I believe when this is understood properly that a better Rocket stove operation can be achieved.  

Yours truly,                 TOM REED                 BEF STOVEWORKS

I don't think I have ever seen an explanation of this, but I would welcome comments.  
> Dear Paul,
>
> I'm glad that we're starting to send small pictures, worth a thousand words
> sometimes and does not clog up my not terribly fast system.
>
> I've often wondered, especially since you started in this direction, whether
> starting a fire above a fire in a chimney would benefit both fires so that
> the result was overall cleaner combustion. Can you determine if this is so?
>
> Does the upper fire clean up escaping smoke from the lower? Does preheated
> hopefully swirling air help the upper fire to burn cleaner? Is there greater
> draft because of the upper fire that assists better burning in the lower
> fire? Are exit temperatures above 1200F? Etc.
>
> Thanks for doing this interesting experiment!
>
> Yes, the top part of your stove is a Rocket. But we certainly have no
> trouble with anyone using Rocket ideas...That's what we're trying to spread
> around!
>
> Best,
>
> Dean