[Bioconversion] switchgrass pellets

[AJH]

On Fri, 20 May 2005 08:34:21 -0400, Jonathan Reeves wrote:

>
>I wish to manufacture switch grass pellets on a small scale (up to a few
>10s of tons annually in the first instance from about 10 acres) for
>pellet stove use by a few locally interested farms/houses.  Does anyone
>have experience of the feasibility of converting switch grass to pellets

First I must apologise for the double posting of this message, I had
not noticed Jonathan had re posted from another address when this one
bounced to me.

I cannot particularly help about pelleting switch grass as I have not
been involved in it. I think the perceived wisdom is that the material
to be pelletised needs to be ground such that the largest piece is
<0.4 of the die diameter and the material needs to contain at least
12% lignin unless a binder/glue is used.

My main thought in this scenario is that pellets attributes are needed
for two things, one to facilitate transport by conventional freight
means and two to cut the cost of a stoker, especially in the sub
50kW(t) sizes.

If the material is to be burned in local stoves then I would aim for
burning in some sort of intermediate densified form, possible small
bales or pucks. Maybe even burned fast and furious and then the heat
meted out via a thermal store. This is because the capital cost of
pelleting may not be recovered by any savings in the capital cost of
the furnace.

I believe there are good reasons for pelleting grasses in mixture with
wood and these are to do with the slagging problems with ash from
grasses as well as chlorine content of some straws causing corrosion.
Diluting the grasses with wood mitigates the problem.

AJH