[Stoves] Pellet stoves - risks

[Frans Peeters]

Dear Frank and all,

    I got the PUF  with pine biomas
But it ONLY happens if the fuel adding is too large !
REAL TLUD is badge and no adding on top but theoretical UNDER the FIRE .
So use 5 more  NEW  TLUDS and refill the cold again .
An automatic pellets stove drops ONLY 5 pelets a second! And never pufs .
No 5Kg at once  !. so you get PUFS like a BULL STEAMING along its ears .

 Frans


Dear Andrew

Can we realistically run a pelleter at 280 C input and save energy? The
output is already charring the material. Perhaps that is torrefaction on the
fly, so to speak. If so, the MJ/kg should rise with processing. 

The pellets are have in Java are 8% moisture (Albasia). IF it gets really
hot and was bagged, it should be zero.

Crispin


Frank on the large scale I doubt it is a problem because as you heat wood up
through 100C and drying and then on to the evolution of some VOCs to this
280 C torrefaction range you are always in an endothermic reaction, let it
slide above 330C and it becomes mildly exothermic, so with a bit of feed
back it should be possible to stay around280C with no thermal runaway. By
thistemperature presumably lignin is quite plastic so pelleting power should
be lower.I'm not sure what chemical changes are taking place but I'm
assuming some hydroxyl groups  are being lost, making the material less able
to attract water i.e changing from hydrophilic to hydrophobic, so unlike
sawdust pellets torrefied pellets should store better without attracting
moisture and disintegrating. What are they like when dropped in a glass of
water for an hour or two?

With large scale it will also be easy to incinerate the low cv offgas given
off bythe process.

AJH