[Stoves] is this new?

[Crispin Pemberton-Pigott]

Dear Alex

 

Well spotted. That combustion chamber was changed some years ago. There are
no holes near the top of the current version (which works better as a TLUD
when desired). 

 

I was able to reduce the number of holes. The Vesto being manufactured in
the Gambia uses the new version as well. 

 

The number of holes below the secondary air lines was also changed to
provide 2 or 3 char-burning pilot flames in case the main flame goes out for
some reason (it gets unstable when the charcoal is nearly gone). This
solution is one way to get the charcoal to burn more or less concurrently
with the gases, or if it was operated in a char-making mode, to burn the
char without losing the fragile flame at the secondary stage. I was always
unhappy with the way gasifiers are going out with any slight disturbance and
found that if the secondary fire is close-coupled to the pyrolysing zone and
there is a pilot flame from below, the top (big) flam re-lights
automatically if some gust of wind blows it out.

 

When burning ball-shaped fuel with a lot of air flowing through (like
perhaps the jatropha seeds) too much air passes through the primary zone. I
think this is part of the cause of the problems reported re smoking
excessively or smoking too much of the time when burning oily seeds. There
is just too much primary air and one ends up with a tall diffusion flame
with no hope of getting enough secondary air mixed into it in the (usually
very) short space provided for the flame.  

 

The simplest cure is to put a paper disk on the bottom of the combustion
chamber to block the air. It will catch fire later one and provide the
needed primary to that will burn the char (if that is desired).

 

If there are some jatropha seeds available in Yogyakarta I will try some to
see what happens. I took a new combustion chamber to them on the past trip.
(That stove is ancient).

 

Regards

Crispin hitting -14 C today and what about that 40 cm of snow?? L 

 

Crispin,
Its been a while since I saw the Vesto. It looks from the pictures like
there are secondary air holes all the way up the central tube. Is that
current?
Seems like the top rows would just be adding tramp air (unemployed air).

Alex




 

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