[Gasification] making wood pellets

[Tom Reed]

Dear All:

According to our book, "Densified Biomass" (?), the power necessary to 
make sawdust pellets (typically 100 Hp hr) is 3% of the energy in the 
pellets.  However, it is electrical energy, so comparing thermal to 
thermal energy it is more like 10%.

TOM REED               BEF

Mark Ludlow wrote:

>Jeff and List:
>
>It seems as though the production of suitable gasifier feedstock may be one
>of the core criteria of successful gasifier operation from woody feedstocks.
>(Forgive me for stating the obvious!) Most of the methods of consolidation
>into forms that do not bridge upon feeding and form suitable char beds upon
>gasification that have been discussed on this list seem energy (and
>capital!) intensive in themselves.
>
>Straw and sawdust can be pelletized with a 'California Mill' type of
>machine, but not a great rates-per-horsepower of shaft power. Small blocks
>of wood are hard to create; the mechanical properties of wood that make it
>so valuable as a construction material also make it difficult to shear,
>split and compress.
>
>It made be appropriate to revisit the fundamental assumptions of gasifier
>designs that specify a tightly regulated form factor for feed. Energy spent
>chopping logs into 30cm chunks is not conserved.
>
>Mark
>
>
>
>-----Original Message-----
>From: gasification-bounces at listserv.repp.org
>[mailto:gasification-bounces at listserv.repp.org] On Behalf Of Jeff Davis
>Sent: Wednesday, August 30, 2006 10:54 PM
>To: gasification at listserv.repp.org
>Subject: Re: [Gasification] making wood pellets
>
>
>On Wednesday 30 August 2006 08:58 am, Gm Parts Source wrote:
>  
>
>>When you speak of the dies are you referring to the necked down area 
>>of an extruder?
>>    
>>
>
>Sounds correct. It's where the pellet gets it's shape.
>It's also the large ring on the ring pelleter.
>
>
>  
>
>>IF so has anyone experimented with a large pellet perhaps using a wood 
>>splitter type setup to generate the pressure and simply compressing 
>>the sawdust into a round tube?
>>    
>>
>
>This is a form of pelleting. Think it's called the hydraulic ram pelleter. 
>It's mainly used for metal shavings from lathes and mills. Kind of slow. 
>
>There is also the mechanical piston pelleter and some people have made them
>from a hay balers. But in regards to biomas fuel, this pelleter suffer from
>variations in copact density and the fuel is not as good as from a screw
>press or I would think ring pelleter. 
>
>
>Jeff
>
>--
>Jeff Davis
>Somewhere 20 miles south of Lake Erie, USA
>http://www.velocity.net/~jeff0124
>
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>  
>