[Bioconversion] Re: [Stoves] Grass Pellets

[Roger Samson]

Andrew

I am plant scientist but will comment as an amateur combustion specialist.
Clinker is formed through the combination of silica combining with the
binders (chlorine and potassium) in the presence of heat, much like the
concept of concrete being formed by sand, cement and water. Silica is not
the problem it is the binder and a high temperature that causes the stuff to
fuse.   

Some suggestions to manage the combustion that are being used by companies

1. keep a low temperature and low primary air where biomass is initially
burning to avoid too high a temperature (you can combust the gases at high
temperature later)
2. keep a live floor, and auger or push out fuel as it burns so that by the
time it is withdrawn it is completed burned out and not mixed with the fresh
fuel being added
3. avoid excess air so that the alkali species migration (heavily induced by
the presence of chlorine) is limited by not having too much air flow out of
the initial combustion zone
Its easier to manage these processes in bigger units. There are many
companies in Canada now selling pretty good technology and exporting. 
 
Roger

-----Original Message-----
From: bioconversion-bounces at listserv.repp.org
[mailto:bioconversion-bounces at listserv.repp.org] On Behalf Of
sylva at iname.com
Sent: Thursday, February 16, 2006 5:37 PM
To: bioconversion at listserv.repp.org
Cc: stoves at listserv.repp.org
Subject: [Bioconversion] Re: [Stoves] Grass Pellets

On Tue, 14 Feb 2006 09:57:28 -0800, Tom Miles wrote:

>If Andrew Heggie agrees alternate fuels for heating appliances might be a
>good topic for the Bioconversion list which seems to have picked up the
>pelleting topic. I would introduce the topic to see if there is interest.
>http://listserv.repp.org/mailman/listinfo/bioconversion

I think the ways and means of getting heat out of more difficult
biomass is worth talking about on Bioconversion.

With a bit of luck we can stay on topic and avoid parochial political
issues or unsolicited commercial posts.

Barley has been mentioned, I burn barley tailings but with 50% wood
pellets. I have a feeling this vastly derates the stove.

Roger Samson has frequently mentioned the difference in potassium (and
chlorine) between over wintered switch grass and summer harvested. The
implication being that winter rain leaches out these components. We
have previously discussed "washing" dung and Richard Stanley's
"retting" will also involve leaching. How about artificially leaching,
in warm water, or a big pressure cooker?

What suggestions other than adding kaolin and limestone have we for
mitigating slagging? How does Roger's advance gasifier stove (not
apparently available outside Canada) avoid the problem?

I have recently had to remove some quite hard white clinker from the
de ashing auger of an industrial woodchip boiler, this from small
dimension willow and I suspect that the higher bark content of small
coppice is the problem.
-- 
Andrew Heggie
please reply to list as I am posting from an account which I do not check,
as REPP are blocking my posts

-- 
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