[Stoves] Burning saw dust in TLUD stove

[Crispin Pemberton-Pigott]

Dear Richard

I certainly like the idea of shaping the load of sawdust to create anything
approaching a constant burn. The main reason for the failure of sawdust
burning stoves to become popular (so I am told) is because the firs starts
off small and gets larger and larger with time until it is a raging inferno
with a huge surface area. Choking it creates massive smoke.

So addressing that is perhaps the main issue. Briquetting is the simplest
obvious approach.

I note that Dedza Pottery uses sawdust to file their kilns, dropping it into
a 'centrifugal fan-like' impeller, falling into a blast of air from a real
centrifugal fan. Certainly that qualifies as a fluidized bed but it is
pretty miserable to operate (continuous attention needed, with a stick in
hand).

How about a downward-angled cone that tapers larger towards the bottom
dropping loose sawdust into a primary air choked region under the combustion
chamber? The Mayon Turbo Stove pretty much does that using a donut of fuel
but it is tapered the other way and manually rattled to feed episodically.

I like Larry's angled 'steps' for larger fires. It raises in my mind the
relationship between the particle size and the distance across the feeder. 6
times? 10 times? 20 times? Which will work without clogging?

Regards
Crispin enjoying Christa's book of micro-gasifiers and fuels...