[Stoves] [Gasification] Grass Fireballs burn cleaner than wood

[Richard Stanley]

Jeff, Tom et al,

Great observations about the effects of retting vis a vis pollutants  
and net energy values, you guys.

I'd just like to add our experientially based two cents to augment  
and strengthen them.

We train the producer to not toss out anything when wet processing.  
The fines and slurried fines which settle out in the mortar and  
pestle (as powdery paste) or out of a chopper masher  (as a powder /  
small flakes), or a hammer mill (as dust), are usually preserved and  
recombined in the mix as fine fibers and infill  material to further  
stiffen and densify the briquette. Personally, however,  I never have  
considered the effect of removing the material to increase its heat  
value. If you are referring to that which is contained in fresh cut  
biomass which  washes/ gasses  off/evaporates  in the early stages of  
insitu decomposition however it very aptly applies to our own  
experience.

I say this because we will tend to use only that which is already  
partially  dried /browned yellowed before the threshing pounding o\r  
milling begins.
Very much in support of this supposition, and holding the type of  
biomass constant, the attempt to directly process freshly cut biomass  
by pounding threshing milling etc., most often assures one of lots of  
smoke & low heat etc. no matter how well the resulting briquette is  
dried before it is ignited.  (Its tempting to do so as the green  
yellow stuff is nice and sticky and gives the illusion of being the  
ideal briquette feedstock  material....

There are briquettes and there are briquettes...

Richard S.

> On Thursday 28 December 2006 04:52 pm, Tom Miles wrote:
>> Direct combustion of grasses can produce significant emissions due  
>> to the
>> volatilization of inorganics and production of submicron  
>> particulates.
>> Fireballing or wet processing such as holey briquetting would  
>> reduce this
>> significantly by removing soluble inorganics. But there may be  
>> applications
>> where charcoal production is a viable alternative as it has been  
>> with the
>> sugar cane tops and leaves.
>
> Below is some interesting information about retting. Source; VITA  
> Tech. Paper
> #46.
>
> My retting may be beyond their retting. In other words, maybe my  
> fuel value is
> less.
>
>
>
> "RETTING AND PRESSING
>
> Partially decayed and processed cellulosic materials give a much
> higher heating value than if the materials are simply dried.  For
> example, dried rice straw (10 percent moisture content) has a
> heat value of only 3,000 BTU/pounds (7 million joules/kilogram
> [J/kg] or 0.0698 gigajoules/kilogram [GJ/kg]), but this will
> increase to between 7,500 (17.4 million J/kg or 0.0174 GJ/kg) and
> 12,000 (28 million J/kg or 0.0279 GJ/kg) when the material has
> partially rotted before it is dried.   In the Philippines, the
> MAPECON research group has set up a pilot plant producing such
> fuel, with 25 percent moisture content and an average of 10,000
> BTU/pounds (23 million J/kg or 0.0232 GJ/kg) which they call
> `green charcoal,' at the rate of one ton per hour.   The group
> reports that it is very competitive with other types of fuel."
>
>
> Best Wishes,
>
> Jeff
>
>
>
>
>
>
> -- 
> Jeff Davis
> Somewhere 20 miles south of Lake Erie, USA
> http://www.velocity.net/~jeff0124
>
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