[Stoves] Meat grinder fuels for TLUDs was Re: wheat husk pellets

Thu Jun 13 16:17:51 CDT 2013

Tom, Paul,
the problem with running a fiberbound residue through, especially, an augur driven meat mincer type die, is that the process itself tends to shear the very fibers that do the binding. 1" dia x 1 long sausages are about as small as you can go from our experience .
Richard

Sent from my iPhone

On Jun 12, 2013, at 21:07, "Tom Miles" <tmiles at trmiles.com> wrote:

> Paul,
>  
> The hulls would have to be incorporated into a meal that when dried would form into a ball or pellet shape by using something like a meat grinder. It might be possible to “ret” them with the coffee skins a la Bryant/Legacy. Then you would have something to form. I have always experienced a large quantity of fines with rice husks and straw. You could tie those up by combining them in a meal but you need something fibrous to hold them together.  
>  
> Think of other uses for composted rice husks. I know someone who has made thousands of cubic yards of peat substitute by composting rice husks. So it is clearly possible to biologically “process” the husks to a beneficial form. Once you have composted the hulls why use them as fuel? They could be better as a soil amendment. The composting should generate biological binders that would give you a choice of densification methods. Pressing hulls through a metal die will just wear out the die. Probably not the first choice. I think there is a form of fuel or soil amendment that could be created. Meanwhile keep the day job and perfect your rice husk TLUD
>  
> Tom
>  
>  
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Paul Olivier
> Sent: Wednesday, June 12, 2013 7:38 PM
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] Meat grinder fuels for TLUDs was Re: wheat husk pellets
>  
> Tom's explanation still leaves me with a few questions.
> Would the rice hull have to be ground into a powder to go through a meat grinder?
> It takes a lot of energy and maintenance to grind up rice hulls.
> With a conventional pellet machine, rice hulls do not have to be ground up.
> What binder would be used with rice hulls?
>  
> Paul
>  
> 
> On Thu, Jun 13, 2013 at 9:08 AM, Paul Anderson <psanders at ilstu.edu> wrote:
> Stovers,
> 
> Tom gave a good explanation.   His message is now in the Listserv Archives.   But how can such content be made more available for future readers?
> 
> 
> Paul
> 
> Paul S. Anderson, PhD  aka "Dr TLUD"
> Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
> Website:  www.drtlud.com
> 
> On 6/12/2013 4:24 AM, Tom Miles wrote:
> Andrew,
> 
> Good explanation.
> 
> Think of two methods of forming fuels. One requires high heat and pressure.
> The other requires water and biological or chemical degradation.
> 
> Heat, pressure and some moisture (10% MC) are required for densification to
> pellets, briquettes or fire logs. A dry biomass is finely ground and pressed
> through a metal die. There are two principal binding mechanisms. In one,
> cellulose fibers pressed together with heat removes excess water and the
> fibers are bonded to each other through what is called paper bonding, or
> hydrogen bonding. It is like wetting two pieces of paper and letting them
> dry out. They are difficult to pull apart. This is a chemical bond that is a
> major bonding mechanism for most densification. When you break the pellet or
> briquette it falls apart rather than snaps.
>   A second mechanism is lignin plastic flow, as Andrew describes below. The
> lignin and part of the celluloses actually plasticize and flow. Under high
> power magnification with a scanning electron microscope a portion of the
> wood looks like solid plastic with no identifiable fibers. These pellets
> snap when you break them.
> 
> Both mechanisms are at play in a densifier. Together these mechanisms make a
> durable pellet or briquette.  As Andrew points out they require power and an
> extrusion process like a pellet mill.
> 
> A third mechanism that is used with mechanical densifiers is adding chemical
> binders, starches, or even expanding clays. These were employed in the
> older, low power cubers and briquetters to make animal feed. Molasses based
> binders were added to help stick hay together in cubes and to add nitrogen
> (protein) etc. They often added 30% to the cost of the feed. We used sodium
> hydroxide to hydrolyze straw to make it pliable for making cubes. It had the
> advantage of making the straw more digestable for the animals. This was fine
> for using low quality feeds like straw in times of feed shortage but too
> expensive when feed prices fell.
> 
> Wet methods of forming fuels are like the method described by Richard
> Stanley. Using water, chemicals, or biological degradation the biomass is
> softened and the surface become sticky. You make a pulp, meal, or dough. You
> can then use a press, like a piston press (a la Bryant), a meat grinder, a
> roller mill, or a cement mixer (Davis) to form the fuel into balls or
> bricks. Then you dry it out. The sticking mechanisms include the paper
> bonding, as described above, and adhesion by any number of sugars, starches,
> etc. that are activated or released by the process. The dried fuel is not as
> dense as a pellet or briquette but it is uniform, it stays together, and It
> burns very well because for the form of the fuel.
> 
> When we worked with Ben Bryant in the 1970s and 1980s we tried a number of
> simple wet pulping processes to make building products for both developed
> and developing countries and fibers for erosion control. Some of his
> products from this period are still made commercially. In the 1990s Ben
> introduced me to Richard and how he was applying some of the same wet
> forming principles to make bricks for fuel (and for growing seedlings). The
> lesson is to learn and understand how natural fibers and fiber chemistry can
> be used to an advantage. Sometimes a small percentage of long wet fibers can
> be used to bind together dry fine particles.
> 
> Torrefaction. Think of torrefaction as roasting biomass fuel in the absence
> of air.  Biomass is heated first to dry it, then in the absence of air to
> 280C. At this temperature it is completely dry and some of the cellulose has
> converted to gas. You lose about 30% of the weight and 10% of the heating
> value. The fuel is in the same form that you started with but it is dry and
> brittle. If you have a densifier then it takes less energy to pelletize it.
> The pellets store well because they resist moisture. Torrefaction is used
> primarily for preparing wood fuel for burning with coal in very large
> utility boilers. There are several torrefaction projects in Europe and a few
> in North America. A plant in Mississippi has shipped a couple of large barge
> loads of torrefied wood to customers in Europe.
> 
> There was a project in Rwanda some years ago that used partial torrefaction
> to prepare fuel bricks for domestic use.  A professor from the US designed a
> small torrefier and installed it in a refuse fuel operation run by a women's
> coop. The torrefied biomass was formed into a brick using a fire log maker
> like the Shimada machine. A USAID employee we contacted knew of the project
> but did not know if it was still in operation. I haven't heard of any
> similar projects at the small scale.
> 
> I hope that this long-winded explanation helps make these processes clear.
> 
> Tom
> 
>    
> 
> 
> -----Original Message-----
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
> ajheggie at gmail.com
> Sent: Wednesday, June 12, 2013 1:01 AM
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] Meat grinder fuels for TLUDs was Re: wheat husk
> pellets
> 
> [Default] On Wed, 12 Jun 2013 12:53:02 +0700,Paul Olivier
> <paul.olivier at esrla.com> wrote:
> 
> How does lignin soften to become a binding agent using a meat grinder?
> This would be truly wonderful, if it were true.
> It won't with a meat grinder, you will need some sort of binder, like
> boiled starch or clay.
> 
> Lignin plastisises under high pressure and heat, the heat is normally
> derived from the friction of the material passing through the die. At
> these pressures the cell walls collapse and then the lignin re sets to
> form a pellet that is denser than the wood it was made from. All these
> systems use a lot of power and the expensive dies wear.
> 
> The Shimada press is the one that produces a hexagonal log with a hole
> down the middle, often blackened on the outside from the heat from the
> press walls.
> 
> Similarly rotary die extruders  use pinch rollers to punch small
> amounts of feed through the holes.
> 
> 
> Have a look at:
> 
> http://www.fao.org/docrep/x5738e/x5738e0j.htm
> 
> 
> AJH
> 
> _______________________________________________
> Stoves mailing list
> 
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
> .org
> 
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
> 
> 
> 
> _______________________________________________
> Stoves mailing list
> 
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
> 
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
> 
> 
> 
> _______________________________________________
> Stoves mailing list
> 
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
> 
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
> 
> 
> 
> 
> -- 
> Paul A. Olivier PhD
> 26/5 Phu Dong Thien Vuong
> Dalat
> Vietnam
> 
> Louisiana telephone: 1-337-447-4124 (rings Vietnam)
> Mobile: 090-694-1573 (in Vietnam)
> Skype address: Xpolivier
> http://www.esrla.com/
> _______________________________________________
> Stoves mailing list
> 
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
> 
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20130613/2570b6a2/attachment.html>