Tom, I am not sure if I understand all that you are saying here. I thought that the potassium compounds melt at 350 C and vaporize at substantially higher temperatures. If most of the K stays in the char, then it does not vaporize at 350 C. Is this correct?
Paul On Sun, Oct 16, 2011 at 11:00 AM, Tom Miles <[email protected]> wrote: > The actually exists as KOH and vaporize starting at about 350 and > increasing in greater proportions as you increase temperature. Once it > vaporizes it condenses quickly with chlorine or sulfur, if present. Only > when it is hot enough (750 C or higher) will it begin to melt, especially If > it is present with silica in a ratio of about 1:2. Husk silica is more > resistant than straw silica to alkali silicate formation. I would think the > most of the K will stay in the char. If you get K volatilization you will > see it where you burn the gas. Over time you’ll get agglomeration of very > fine (submicron like cigarette smoke) particles that we call an alkali fume. > At such low fuel rates you’re not likely to see anything for some time. > **** > > ** ** > > Using the rice husk as a pilot fuel for the coffee husk makes a lot of > sense. You’ll get a clean gas and a rich husk char. **** > > ** ** > > Tom**** > > ** ** > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Paul Olivier > *Sent:* Saturday, October 15, 2011 5:17 PM > *To:* Discussion of biomass cooking stoves > *Subject:* Re: [Stoves] why does coffee husk biochar smell like urine?**** > > ** ** > > Frans, > > When subjected to temperatures greater than 350 C, > are you saying that K2O melts but does not vaporize? > Are you saying that we end up with melted K2O? > If the original coffee husks contains 36% to 38% > then the final biochar must contain at least twice that amount. > If this is correct, then coffee husk biochar must be quite valuable, > not only as a soil amendment but also as a fertilizer. > Surely this cannot be right. > > The coffee husk contains some sort of oily substance > that begins to volatilize at temperatures as low as 170 C. > When gasified it produces a lot of black soot. > I tried many burner designs in the last few weeks to get rid of the soot > and to turn orange flames into blue. > Supplying hot premixed secondary air does not effectively consume this > soot. > Sometimes it makes things worse. > > A few days ago I cheated. > I mixed coffee husks and rice hulls in equal volumes. > (Note that the coffee husk has a bulk density of 180 kg/m3, > while the rice husk has a bulk density of about 100 kg/m3.) > The flame at the base was blue and white. > This is the first time I saw the color white in the gasification of coffee > husks. > As the flame rose, it split into two parts: > one part vertical and the other part more horizontal. > The vertical part was blue/white and the more horizontal part was orange. > But there were no streaks of black within the orange part of the flame and > no visible soot. > > The gasifier that I used looked like this: > > http://dl.dropbox.com/u/22013094/150%20Gasifier%20Drawings%20PDF/001%20-%20150%20Gasifier%20Assembly.pdf > Note the burner design: > it is a Belonio burner with two rings of burner holes, together with a > burner housing. > This burner design gives by far the best result. > Secondary air is sucked up between the housing and the burner. > It then moves from vertical to horizontal, > and from here it hits the two rings of holes that are offset from one > another. > > The best result, of course, is with 100% rice husks. > With the current burner design, the flame is totally blue right from the > very beginning. > > When I mixed rice hulls with coffee husks (half/half by volume), > not only does most of the soot disappear, > but the burn is quite consistent and steady from beginning to end. > > Paul > > **** > > On Sun, Oct 16, 2011 at 5:35 AM, Frans Peeters <[email protected]> > wrote:**** > > Dear Paul ,**** > > **** > > I did many times fusions with pure KOH .**** > > At 350° C it melts and is very aggesive to dissolve ceramics Al2O3 and SiC > powders . (Diamond recup. )**** > > It is verry verry hygroscopic and the hydroxyde airosols with water in the > air gives your nose sense alcalic .**** > > Your brain makes the link to urine . but not the real potasium make it .** > ** > > It goes not into gas but sputers airosols has a special creep effect out > of a creuset .! Even after cooling .**** > > Also a battery and fuel cel with KOH . It creeps in a isolated conductor > for 20 cm after years ,and destroys manny apparati .**** > > KOH Is colourless but Nickel gives yellow.salts .**** > > It does not become K2O2 becouse to destroy SiC we must ad Na2O2 to oxydize > the carbide .**** > > Potasium is to measure with flame spectro 440 um purple colour in a > hydrogen flame . (Sodium =yellow . Cupper =green Sr =red**** > > Sorry ,I drink no coffe ! But have a friend who drinks pee ….** > ** > > **** > > Regards**** > > Frans**** > > **** > > **** > ------------------------------ > > *Van:* [email protected] [mailto: > [email protected]] *Namens *Paul Olivier > *Verzonden:* zaterdag 15 oktober 2011 9:07 > *Aan:* Discussion of biomass cooking stoves > *CC:* Will Rutherford; loren cardeli; CHRISTA ROTH > *Onderwerp:* [Stoves] why does coffee husk biochar smell like urine?**** > > **** > > Christa, > > Do you have any idea why coffee husk biochar smells like urine? > > I just read that coffee husks contain 36% to 38% K2O. > This supposedly accounts for the low melting point of its ash. > That its ash has a low melting point makes sense to me, > since, if I leave the fan on a bit too long after the gasification cycle is > finished, > I see a stony yellowish/white ash at the bottom of the reactor. > > How is this possible that coffee husks could have so much K2O? > What happens to the K2O when it is subjected to heat? > I see that K2O has a melting point > 350C. > If subjected to heat does it turn into K2O2 or even KO2? > At what point does it turn into a gas? > > Does the presence of K2O account for its urine smell? > What does this urine smell mean with regard to the value of coffee husk > biochar? > Would coffee husk biochar be rich in potassium? > > Paul > -- > Paul A. Olivier > 27C Pham Hong Thai Street > Dalat > Vietnam**** > > > _______________________________________________ > 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://www.bioenergylists.org/ > > **** > > > > > -- > Paul A. Olivier PhD > 27C Pham Hong Thai Street > 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://www.bioenergylists.org/ > > > -- Paul A. Olivier PhD 27C Pham Hong Thai Street 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://www.bioenergylists.org/
