Insulation seems to be a common problem in many parts of the world. I wonder just how difficult it can be to form little balls ( 10 -15 mm?) of clay mixed with a high portion of sawdust or the like and burn them to 900 degrees C, which should be possible with a large TLUD . This could be something like "pop clay" and shure has some nice properties.
Anyone knows about it? Rolf On Fri, 14 Jun 2013 01:25:38 -0700 "Rebecca A. Vermeer" <[email protected]> wrote: > Paul, > I currently use wood ash as insulating material between the kalan and > combustion chamber of the eco-kalan (a rocket stove using wood, charcoal, > coconut husk, shell, fronds and other parts of the coconut tree). The > eco-kalan uses 75-85% less firewood and therefore a lot less ash is produced > compared to traditional kalans and other traditional cookstoves in Negros > Oriental, Philippines. A shortage in supply of ash is one factor which > affects sales of eco-kalan. I have considered making an insulating > material using a 50-50 mix by volume of rice hull & clay in the form of > pellets or bricks which would be broken to pieces after firing. I would fire > the pellets or the bricks along with the eco-kalans up to 900 degrees > Celsius. Will there be significant formation of cristobalite under these > conditions? Would handling the fired pellets or the breaking of the bricks > be a health hazard? Thanks, > > Rebecca Vermeer > > From: Paul Olivier > Sent: Friday, June 14, 2013 12:07 AM > To: Rebecca A. Vermeer > Cc: Jon Anderson ; [email protected] ; larry winiarski > Subject: Re: Fw: [Stoves] : Re: Insulation and stove life > > Rebecca, > > If we directly burn river hulls, there should be a lot of cristobalite > formed. If we gasify, this problem should be minimized, provided channeling > does not occur. Also there might be cristobalite in the particulate matter in > the combustion gases. With rice hull pellets in a TLUD we have a lot less > channeling, and a lot less particulate matter. Therefore the rice hull pellet > becomes an attractive fuel for these and many other reasons. > > Thanks. > Paul Olivier > > On Jun 14, 2013 1:44 PM, "Rebecca A. Vermeer" <[email protected]> wrote: > > Hello Paul, > Larry just told me that the silica content of rice hull ash is over 90%. > At the ETHOS 2013 Conference, I saw a TURBO stove developed in the > Philippines which used rice hull for fuel. Given your comment below > regarding cristobalite “which is a nasty carcinogen” and severely hazardous > to human health (see link below), would you recommend the use of rice hull > as a household fuel for cookstoves? > > Rebecca Vermeer > > CRISTOBALITE LINK: > http://nj.gov/health/eoh/rtkweb/documents/fs/1657.pdf > From: Paul Olivier > Sent: Wednesday, June 12, 2013 12:01 AM > To: Discussion of biomass cooking stoves > Subject: Re: [Stoves] : Re: Insulation and stove life > > Paal, > > > One thing I look for on my burner is that all burner holes support a flame > throughout the process. If channeling occurs during the process or if char is > being burned as the process comes to a close, then one can see burner holes > that do not support a flame. This means that CO2 is being discharged from the > burner holes, and of course CO2 does not burn. When CO2 is formed, this > represents a big inefficiency, since combustion takes place far below the > pot. When this happens the sides of the reactor can easily turn red hot and > melt. I do not know how it is possible to spot the presence of CO2 if the top > of the reactor stays open and does not have a lid with burner holes. > > > If one turns up the fan a bit too high resulting in channeling, it can > happen that only a few holes (among a total of 80 in my case) do not support > a flame. If I turn the fan down a bit and shake the reactor, this problem is > immediately corrected. Also the effect of the presence of CO2 can be spotted > by the cook in another way. The distribution of heat to the pan is not even. > > > Also many of the positive characteristics of biochar are lost when biochar > is combusted and is reduced to ash. The combustion of biomass and biochar > takes place when channeling occurs, and the combustion of biochar takes place > if the fan is not turned off at the end of the process. Rice hull ash and > rice hill biochar are not at all the same thing when it comes to growing > plants. Also rice hull ash can easily contain cristobalite, which is a nasty > carcinogen. Under ordinary conditions, no farmer should be handling this > stuff. > > > Thanks. > > Paul > > > > > On Wed, Jun 12, 2013 at 1:06 PM, Paal Wendelbo <[email protected]> wrote: > > Ron > > By end of flame the color of the char is red to yellow, that indicate a > temperature of 700 to 800 ˚C and when there is no smoke, complete combustion > has taken place. Is that not good for biochar? > > Regards Paal W > > > _______________________________________________ > 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/ > -- Energies Naturals C.B. <[email protected]> _______________________________________________ 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/
