[Stoves] Retted Switchgrass Fireball Test

[Roger Samson]

Jeff

In Ohio, you should be able to late fall cut the switchgrass and winter bale
it on frozen ground or in the spring. With winter or late spring harvest of
upland ecotypes of switchgrass you should be able to get potassium levels of
around 0.05% and chlorine levels of 0.01% (ie more or less the same as wood
pellets). With this chemical composition, alkali species migration from high
temperature combustion is not much of an issue. 

I have had some feedback from commercial boilers users that herbaceous fuels
like switchgrass need to be fairly dense to burn effectively. Some have
suggested a bulk density range of 35-50 lbs/cu foot or 550-800 kg/m3 is
required. It maybe that herbaceous fuels, unlike wood are too quick to
release their gases and then it's difficult to control the combustion
process. In China several people have suggested to me that mixing coal fines
into densified herbaceous fuels as a way to improve the quality of
combustion and keep fuel costs competitive with coal in standard coal
cookstoves.  In Canada, we are getting high quality combustion from crop
milling residues or switchgrass pellets in boilers and pellet stoves. These
fuels have wood pellet like bulk densities of around 700 kg/m3. 

I wonder what the density of your switchgrass fireballs are?

Roger Samson
www.reap-canada.com





-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Tom Miles
Sent: Saturday, September 02, 2006 6:51 PM
To: 'AJH'
Cc: stoves at listserv.repp.org
Subject: Re: [Stoves] Retted Switchgrass Fireball Test


Andrew,

I agree with you about the need to increase temperatures. 

A hazard of higher temperatures from char combustion when burning straw is
the potential to melt ash constituents in the straw or corrode the metal
parts with alkali salts. This could be partially offset by combined firing
with wood or paper.   

Tom

 
-----Original Message-----
From: 'AJH' [mailto:list at sylva.icuklive.co.uk] 
Sent: Saturday, September 02, 2006 3:08 PM
To: tmiles at trmiles.com
Cc: stoves at listserv.repp.org
Subject: Re: [Stoves] Retted Switchgrass Fireball Test

On Sat, 2 Sep 2006 12:58:40 -0700, Tom Miles wrote:
<snip>

It makes me think that to burn the fireballs Jeff had trouble with you
will need to up the temperature in the primary zone of the tlud, which
is going to mean increasing air supply and burning a bit of char. This
off course has major implications for the life of the metal parts.

AJH





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