[Stoves] Cuber and size of densifying machines. (no longer Re: The wood and char and fuel "debate" )

[Ronal W. Larson]

Andrew, Richard, list

	1.  I haven’t seen the topic of “holey” briquettes in this recent discussion.  About 15 years ago, this was a big deal on this list.  I think the hockey puck shape has many merits, but I believe both combustion and pyrolysis is much improved with one or more holes in the puck.  The reason is the more efficient capture of radiant energy from the flames.   Of course the puck with holes also dries better/faster.  I wonder if the puck density increases (optimizes) with holey pucks (not bulk density - which obviously goes down).  Any studies of optimum diameter or length of the hole  (optimum in a combustion or pyrolysis sense) with puck shapes ?

	2.   I have not seen any statistics on optimum bulk density.  I believe the holey puck is so much superior to the plain puck that we can say that highest possible density is not what we want.  Others have noted that wood can be too dense for good operation.  Might that too dense material become useable with holes?

        3.  I would like to see the difference between “spheres" with and without a central cylindrical hole.   During the last stove camp, I made and reported on hand-making ellipsoids that were not too far from spheres.  Others didn’t conclude what I did - that I could make a quite dense “sphere” with one hand.  Now I wished I had tried something with two hands (maybe a little bigger than a golf ball), but with a central hole so we could get water out, and then dry, more easily.  The central hole also supposed to act like a hole in a “holey” briquette, by capture of radiant energy.  

         4.  The reason to bring this up is to see if we can better understand the influence of both shape and holes.  I don’t see a good way to make holey spheres in machines, but I can’t see any better shape if done with hands alone.  So this is hoping others will give attention to shapes and holes.   And ways to make something like a sphere - which has to provide air paths that have consistency (thinking of the poor air flow through a container of coin-like shapes). 
     I don’t see pellets helping in this category of the study of holes, but optimum pellet diameter and length are still worth studying.

Ron


On Mar 8, 2014, at 7:50 AM, ajheggie at gmail.com wrote:

> [Default] On Thu, 6 Mar 2014 17:46:38 -0600,Richard Stanley
> <rstanley at legacyfound.org> wrote:
> 
>> Good point frank,
>> Its also about getting the fines  to flow in and around the particles fibers etc., without too much pressure. We use a soupy water (only 20 - 30 percent solids usually) as the carrying agent. It requires a  lot  less pressure  --and results in a lot less wear and tear on the much less expensive machine– than high pressure screw ram melting lignin or even the eccentric roller within a screen die mill. But its a lot less sexy too…
>> Richard 
> 
> 
> Richard your system is more akin to papermaking where the fibres are
> separated from the rest of the wood and then dry on a mesh which
> eliminates the air spaces, paper has a density >1 whereas the dry raw
> wood will be around 0.4 and of course chipping increases the bulk
> density such that 1m3 of dry wood weighing 400kg will occupy 3m3.
> 
> AJH
> 
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