On 11/6/2005 7:18 PM Robatoy mumbled something about the following:
In article ,
Andy Dingley wrote:


Anyone have experience of bulk sawdust disposal? I'm looking into the
possibility of a pelletising press as a way of turning useless sawdust
into a storable and possibly saleable pellet fuel. However all the
pellet presses I've seen have been huge and expensive, intended for use
by a pellet-making plant, rather than just intermittently disposing of
waste from a small timberyard.

I also note that meat-packing screw presses are cheap and commonplace
S/H, but sawdust pellet presses are anything but. Anyone heard of a DIY
conversion process ? I'm expecting that hard-facing the screws would be
needed, but a little engineering work is no problem.


I found that pressed sawdust logs are invariably mixed with some sort of
binder. I'm trying to understand if it is even possible to get sawdust
to stay together after a shape has been made from it...pellet, log,
whatever.
If one is going to have mix it with a binder, is a lot of pressure even
needed or can it be done passively in say, a muffin tin-like form?
Can some information be gleaned from the folks that make feed pellets?

Just mulling things over..

Is applying 'work' to the making of a pellet of sawdust in the hope of
it yielding energy when burned going to give you a positive yield?


After doing some digging around on google, I've found this much out
about pellet mills.

Sawdust is run through a hammermill to bring it to some uniform size
(whatever size that is supposed to be), run through a drum dryer to
bring it down to about 10% RH. Steam heated to some specific temp that
I can't find, then pressed through a die creating 1/4in (6mm) diameter
pellets ranging from 1/2in (13mm) to 1 in (25mm) in length. They are
then cooled and screened and vacuumed before being heat sealed in bags.
No binders used at all.

Fuel cost comparison

Premium Wood Pellets Per Ton Per mm BTUs
8200 BTUs/lb. $180.00 $13.71
80% efficiency

Propane Per Gallon Per mm BTUs
90,000 BTUs/gallon $1.80 $30.80

Electric Per KWH Per mm BTUs
3415BTUs/kwh $0.10 $30.80
95% efficiency

Oil #2 Per Gallon Per mm BTUs
138,000 BTUs/gallon $1.80 $16.29
80% efficiency

Natural Gas Per MCF Per mm BTUs
100,000 BTU $1.60 $20.00

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