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 <[email protected]>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" <[email protected]> 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:[email protected]<[email protected]>] > *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 <[email protected]> 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: [email protected] 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:[email protected]] On Behalf Of > [email protected] > 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 > <[email protected]> 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 > [email protected] > > 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 > [email protected] > > 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 > [email protected] > > 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 > [email protected] > > 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 > [email protected] > > 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/
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