[Stoves] Jatropha fruit as fuel?

[Crispin Pemberton-Pigott]

Dear Bjarne

It is now clear - there are two sections of the stove - a gas making unit
and a mixing/burning unit.

I am still missing one critical piece of information: where does the
secondary air enter the upper unit? It seems to have all the basic parts in
place. 

There is a feature, not in the positive sense, that man gasifiers have which
is to separate the gas burning from the fuel bed. There is no essential
reason for doing this. It actually introduces two new problems that should
not be there which are: separating the radiated heat from the underside of
the flame from fuel bed and the addition of the problems related to the
flame going out and not re-lighting.

Thus, where you add the secondary air is critical. It can prevent both
problems. It would be unfortunate if you were spending money and effort to
create a problem that should not be there.

I did not realise without the photos that you had a removable upper section.
The photos helped a lot in clearing that up. If the secondary air were
pushed into the gas at the top of the fuel containing section and the plate
with the triangular holes were not present, what happens? If there was the
same top round disk placed at the top if the fuel container - or better, at
the bottom of the upper unit so it is removable - it would push the
secondary air into the gas near enough to the fuel to help keep it hot. The
'disk' could have any of a number of complex shapes to promote mixing, but
the point is that the secondary air should not be added near the top because
it means the flames will be running against the pot spoiling the CO and PM
burn. That is why I am asking about where (am perhaps how) the secondary air
is introduced.

The stove looks quite strong.

Regards
Crispin


Dear Crispin
Here is some pictures of the Jiko Bomba casification cookstove.
The first shows the two part of the stove with pellet as fuel in the firebox
before fire is lit.
Second show the stove burning.
The third the same, in the end of the gasification.
The forth shows the charcoal stage where the pellets remains as glowing
carbon. A pot can be put on top of the bottom part of the stove, there are
three supports for that.

Yours
Bjarne Laustsen