[Stoves] Char retort question

[ajheggie at gmail.com]

[Default] On Fri, 31 May 2013 00:30:27 -0400,"David G. LeVine"
<dlevine at speakeasy.net> wrote:

>Let me start with "This is something I think I remember seeing."
>
>Given a mass of biological matter (no, I don't care if it is twigs, 
>grass or tree stumps), put it in a horizontal 55 gallon drum with a band 
>clamped head and a pipe from the top of the head down and under the drum 
>with holes in the pipe which is parallel to the drum.  Once filled 
>(maybe not full either), a fire is started with scraps until the gasses 
>coming out of the pipe burn.  This means the heating becomes self 
>sustaining and the carbon is unlikely to be vaporized, but the gasses 
>driven off are used, not wasted.  Suddenly the pollution is reduced and 
>the efficiency goes up.
>
>1. Does this ring a bell in anyone else's mind?
>
>2. Does this sound like a viable approach?

Yes it's the system originally developed by Lurgi for coal pre WW2 and
has been revived many times, in England Robbie Webster promoted it
about 10 years ago and I suspect the Adam Retort uses a similar
feedback path. The limitation is the poor surface area through which
the heat can pass, not a big problem with dry wood.

It is viable but think of the timeline of how pyrolysis develops, the
offgas does not evolve evenly and its calorific value changes during
the process, this tends to mean most of the heat from the offgas is
happening after the main charge is carbonised. Yury Yudkevitch
addressed this problem by having a series of cylinder retorts feeding
a central offgas manifold which then heated the "oven" space in which
the cylinders sat, removing cyclinc=ders and replacing with fresh in a
batch sequence.

AJH