Re: [CAD_CAM_EDM_DRO] Re:Of Shops and Heat

Gerald;
These were very common in Oregon up until shortly after WWII. Several
companies tried to capitalize on the idea during the energy scams of the
1970's. One such company suckered our university into putting in a huge
sawdust fired heat plant using the "latest technology". They took it out
later.

This is not to say that sawdust heaters don't work. The problem is that
they are cranky. Things like moisture content, chip size and even fiber
orientation in relation to the cut all have a significant effect on
combustion. More than one company tried to overcome these problems by
pelletizing the sawdust (miniature Presto logs). It worked but the cost of
pellets defeated the whole purpose - free heat.

The most successful sawdust burners I've seen use fluidized bed combustion.
This amounts to forcing pre-heated air up through a bed of sand and into the
combustion pile. It helps prevent the pile from smothering itself in
unburned combustion gasses. How well it works on a small scale, I have no
idea.

The other common feature of successful systems is continuous feed (as
opposed to batch feed) of the fuel. This is also their weakness. The fuel
must be kept at just the right moisture content. Too wet and it kills the
fire. Too dry and the fire creeps back through the conveyor system and
ignites the fuel reserves. Too much fines in the air and you get a nice big
explosion.

The university physical plant was right across from the mechanical
engineering building. We were treated to many demonstrations of skill from
the local fire department.

The Swedish are much better at making these things work and I understand
sawdust burners are common there. Might try an internet search.

Doug

----- Original Message -----
From: <Area51tats@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Wednesday, December 27, 2000 7:56 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re:Of Shops and Heat


> Would you be willing to give a more accurate description of the saw dust
> burner? I would like to build one for my shop. I have a cabinet mfg near
by
> that throws away literaly tons of sawdust.
>
> Gerald
> Iowa
> -29 F. on xmas morning
>
>
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