[Stoves] Fw: : Re: Insulation and stove life

[Paul Olivier]

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" <ravermeer at telus.net> 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 <paul.olivier at esrla.com>
>  *Sent:* Wednesday, June 12, 2013 12:01 AM
> *To:* Discussion of biomass cooking stoves<stoves at lists.bioenergylists.org>
> *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 <paaw at online.no> 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
>>
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>
>
> --
> Paul A. Olivier PhD
> 26/5 Phu Dong Thien Vuong
> Dalat
> Vietnam
>
> Louisiana telephone: 1-337-447-4124 (rings Vietnam)
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