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

Thu Jun 13 19:24:55 CDT 2013

Thanks so much, Richard, but that size is too big for a TLUD.

Paul

On Fri, Jun 14, 2013 at 4:17 AM, Legacy Mail <rstanley at legacyfound.org>wrote:

> 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<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
>
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> --
> 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/ ****
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-- 
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/
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