Stephen, What I am trying to do now is to highlight the danger of directly combusting rice hulls. If the rate of gasification remains low (at 100 kg/M2), I do not suspect that cristobalite will be formed in a TLUD. I sent some rice hull biochar from my gasifiers to Josh Kearns. I hope that he tests it for the presence of cristobalite.
Thanks. Paul On Sat, Jun 15, 2013 at 5:29 PM, Stephen Joseph <[email protected]>wrote: > Hi Paul > > No we are pyrolysing them in the outer chamber so they are not subjected > to direct combustion. > > Mr Khoi's stove is not a TLUD. I would not recommend people use TLUD > stoves for rice husks unless they cover the husks with wet clay and then > dry the clay. This coating has the advantage of keeping the temperature > down and also activating the surface > > In any of my TLUD work I try to get people to coat their biomass in an > iron rick clay to improve both CEC and yields. > > Regards > Stephen > > > On Sat, Jun 15, 2013 at 7:40 PM, Paul Olivier <[email protected]>wrote: > >> Stephen, >> >> Are you burning rice hulls at a temperature less than 450 C? >> >> Paul >> >> >> On Sat, Jun 15, 2013 at 4:10 PM, Stephen Joseph >> <[email protected]>wrote: >> >>> I paul >>> >>> Not if you use the design with an inner fire box and an outer pyrolysis >>> chamber as is Mr Khois design. In fact it is the main reason why I >>> recommended this design configuration and sizing to PED. >>> >>> We did a large research project with the Australia Government research >>> arm ACIAR to optimise the design. >>> >>> I have measurde the rice husk temperature in this outer chamber and it >>> stays pretty uniform at around 450C after the initial drying and >>> torrefaction phases. >>> >>> >>> Regards >>> Stephen >>> >>> On Sat, Jun 15, 2013 at 5:55 PM, Paul Olivier <[email protected]>wrote: >>> >>>> But, Stephen, temperatures can rise above 900 C when burning rice hulls. >>>> If we operate at low temperatures (450 C) in burning rice hulls, are we >>>> not inevitably making a lot of smoke? >>>> Even at relatively low average combustion temperatures, will there >>>> not be a tendency for hot zones to form within the combustor? >>>> >>>> Paul Olivier >>>> >>>> >>>> On Sat, Jun 15, 2013 at 2:44 PM, Stephen Joseph <[email protected] >>>> > wrote: >>>> >>>>> All >>>>> >>>>> There has been a lot of work done on formation of crystobalite. The >>>>> rate of formation is both a function of time and temerature >>>>> >>>>> If you have low temperatures (450c) and short times (<60 minutes)you >>>>> wont produce it. >>>>> >>>>> Mehta in India did a lot of work on this in the 80's and published a >>>>> book on rice husk ash cement if I remember correctly >>>>> >>>>> Regards >>>>> Stephen >>>>> >>>>> >>>>> On Sat, Jun 15, 2013 at 5:20 PM, Paul Olivier >>>>> <[email protected]>wrote: >>>>> >>>>>> Tom, >>>>>> >>>>>> I found this news report: >>>>>> >>>>>> http://www.ipsnews.net/2009/10/thailand-renewable-energy-not-so-clean-and-green-after-all/ >>>>>> Not such a nice story. >>>>>> I do not think it's a good idea to burn rice hulls or rice straw in >>>>>> either power plants, brick kilns or household stoves. >>>>>> >>>>>> Paul >>>>>> >>>>>> >>>>>> On Sat, Jun 15, 2013 at 1:10 PM, Paul Olivier <[email protected] >>>>>> > wrote: >>>>>> >>>>>>> Tom, >>>>>>> >>>>>>> I have read in many articles that cristobalite can form at >>>>>>> temperatures of about 900 C. >>>>>>> http://www.jicosh.gr.jp/old/niih/en/indu_hel/2004/pdf/42-2-24.pdf >>>>>>> In burning rice hulls, temperatures can easily exceed 900 C. >>>>>>> If cristobalite forms and is breathed in, human health is severely >>>>>>> impacted: silicosis, tuberculosis, cancer and so forth. >>>>>>> >>>>>>> *Silica (SiO2) is a constituent of the ash produced by the >>>>>>> combustion process. Different >>>>>>> types of biomass fuels contain different quantities of silica. The >>>>>>> International Agency for >>>>>>> Research on Cancer has classified silica as a human carcinogen. Long >>>>>>> term inhalation >>>>>>> of airborne silica particulates can cause lung cancer or other >>>>>>> related health problems. >>>>>>> As rice hull ash contains high levels of silica (~15%), its use as a >>>>>>> biomass fuel >>>>>>> presumably increases the risk of developing silicosis-related >>>>>>> illnesses, and care should >>>>>>> be used in handling the ash.* >>>>>>> >>>>>>> http://www.reap-canada.com/online_library/IntDev/id_eco_sugarcane/7%20Strategies%20for.pdf >>>>>>> >>>>>>> *Silica (SiO2) is the main mineral component of rice husk ash (RHA) >>>>>>> (85-90 per cent). It carries serious health risks, particularly to the >>>>>>> respiratory system.* >>>>>>> http://www.dhf.uu.se/pdffiler/cc7/cc7_web_art4.pdf >>>>>>> >>>>>>> Cristobalite can be present in both the ash and fly ash. If someone >>>>>>> designs a stove to burn rice hulls or rice straw, he has to be sure that >>>>>>> temperatures remain below the point of cristobalite formation. >>>>>>> >>>>>>> Paul >>>>>>> >>>>>>> >>>>>>> On Sat, Jun 15, 2013 at 11:18 AM, Tom Miles <[email protected]>wrote: >>>>>>> >>>>>>>> Paul,**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> After discussing rice hull combustion and gasification at some >>>>>>>> length you are now saying this is dangerous. Why, specifically? You >>>>>>>> have >>>>>>>> discussed the potential to emit cristobalite but there is no evidence >>>>>>>> of >>>>>>>> the hazard it presents. What evidence do you have that burning rice >>>>>>>> husks >>>>>>>> or rice straw is a health hazard?**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> Tom **** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> *From:* Stoves [mailto:[email protected]] *On >>>>>>>> Behalf Of *Paul Olivier >>>>>>>> *Sent:* Friday, June 14, 2013 8:56 PM >>>>>>>> *To:* JJ Claire; Discussion of biomass cooking stoves >>>>>>>> *Subject:* Re: [Stoves] Chimneys, rice husks [Ovens]**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> JJ,**** >>>>>>>> >>>>>>>> I would not recommend that you burn rice hulls ir rice straw.**** >>>>>>>> >>>>>>>> In many cases this is quite dangerous.**** >>>>>>>> >>>>>>>> Paul**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> On Sat, Jun 15, 2013 at 9:40 AM, JJ Claire <[email protected]> >>>>>>>> wrote:**** >>>>>>>> >>>>>>>> Greetings one and all,**** >>>>>>>> >>>>>>>> I visit the Philippines often and usually stay about six months a >>>>>>>> year. **** >>>>>>>> >>>>>>>> I often use a rice hull stove. I would like to get a plan to build >>>>>>>> a **** >>>>>>>> >>>>>>>> concrete stove. I am also wondering if there is such a thing as >>>>>>>> building **** >>>>>>>> >>>>>>>> an 'oven' using cement and/or concrete? I would like to build one, >>>>>>>> **** >>>>>>>> >>>>>>>> a white model if possible, [vice a black model], if such a plan is >>>>>>>> **** >>>>>>>> >>>>>>>> available and if the technology would be practical. We have a **** >>>>>>>> >>>>>>>> lot of rice hulls and not all that much firewood. **** >>>>>>>> >>>>>>>> I would be open to heating the oven with firewood and then **** >>>>>>>> >>>>>>>> maintaining the heat level with or by burning rice hulls. I have** >>>>>>>> ** >>>>>>>> >>>>>>>> a lot of rice hulls and want to make the best use of the hulls.**** >>>>>>>> >>>>>>>> I currently use the wood ashes to make lye so I can make soap, **** >>>>>>>> >>>>>>>> but I have not used any ashes from rice hulls to make lye. I**** >>>>>>>> >>>>>>>> wonder if making lye with rice hulls is possible.**** >>>>>>>> >>>>>>>> The rice hull stoves we use are sort of a metal pail with a wire >>>>>>>> rack. **** >>>>>>>> >>>>>>>> I am looking for a stove, hopefully one that is hot, medium and >>>>>>>> cool, **** >>>>>>>> >>>>>>>> for cooking with rice hulls over a long number or years. **** >>>>>>>> >>>>>>>> On our island, rice hulls are still burned to 'get rid of them', >>>>>>>> and **** >>>>>>>> >>>>>>>> believe it or not, rice straw is still burned. I often ask >>>>>>>> neighboring**** >>>>>>>> >>>>>>>> farmers to bring me their straw and provide them a small bit of *** >>>>>>>> * >>>>>>>> >>>>>>>> cash for doing so. We use the rice straw for making compost.**** >>>>>>>> >>>>>>>> We add some rice hulls to the compost. Most of the rice hulls**** >>>>>>>> >>>>>>>> are burned for fuel to cook with. We add the char from the cooking >>>>>>>> **** >>>>>>>> >>>>>>>> process to the garden. I am wondering if we are making the best*** >>>>>>>> * >>>>>>>> >>>>>>>> use of the rice hulls and if the plans I am speaking of by post *** >>>>>>>> * >>>>>>>> >>>>>>>> are available. **** >>>>>>>> >>>>>>>> Please inform, I am open to suggestions and direction.**** >>>>>>>> >>>>>>>> Blessings,**** >>>>>>>> >>>>>>>> JJ**** >>>>>>>> >>>>>>>> **** >>>>>>>> >>>>>>>> *From:* "[email protected]" <[email protected]> >>>>>>>> *To:* Discussion of biomass cooking stoves < >>>>>>>> [email protected]> >>>>>>>> *Sent:* Friday, June 14, 2013 5:02 PM >>>>>>>> *Subject:* Re: [Stoves] Chimneys, rice husks**** >>>>>>>> >>>>>>>> >>>>>>>> [Default] On Fri, 14 Jun 2013 17:37:30 -0400,"Crispin >>>>>>>> Pemberton-Pigott" <[email protected]> wrote: >>>>>>>> >>>>>>>> >We are experimenting in Indonesia with draft-operated buoyancy >>>>>>>> balancers to limit the pull to the ideal even when combustion >>>>>>>> conditions >>>>>>>> change in the large wood stoves. They are easy and cheap to make. They >>>>>>>> are >>>>>>>> mounted on the side of the stack of all oil furnaces. >>>>>>>> >>>>>>>> We have used them on pellet stoves (which have their own id fans) to >>>>>>>> limit draught on an insulated ss chimney that rose through 4 >>>>>>>> floors. I >>>>>>>> wasn't entirely happy with the idea as it raised the possibility of >>>>>>>> the boiler room getting combustion products if the seal wasn't >>>>>>>> good, I >>>>>>>> would have been happier if the air was sucked from outside. In fact >>>>>>>> there was subsequently a problem but this was down to poor >>>>>>>> maintenance. >>>>>>>> >>>>>>>> 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/ >>>>>>>> >>>>>>>> **** >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> 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/ >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> 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/ >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> 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/ >>>> >>>> _______________________________________________ >>>> 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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