[Stoves] : Re: Insulation and stove life
Paul Olivier
paul.olivier at esrla.com
Fri Jun 14 04:50:39 CDT 2013
Here is Vietnam I saw bricks being made in a most unusual way. Coal fines
of a 40% ash content (costing $100 US dollars per ton) were mixed with clay
and formed into bricks. The bricks were stacked in a tall vertical kiln. A
fire was lit at the bottom of the kiln, and the coal inside the bricks
began to burn creating a brick riddled with tiny air pockets. The fire at
the bottom of the kiln was only needed in the very beginning of the
process. The bricks burned in a self-sustaining manner via the coal on the
inside. I wondered at the time if finely ground coffee husk biochar could
be substituted for coal. And instead of building a messy fire underneath
the column of bricks, gasifier heat from multiple gasifiers could be used
to do the initial firing of the kiln. The Vietnamese like these insulated
bricks.
I have been recently asked to visit this brick kiln again. It's hard to
believe that the process works as I have described. The owner of the brick
kiln has complained to me that he can no longer afford to transport such a
dirty coal from the north of Vietnam.
I built a 250 gasifier that mixes secondary air with the syngas before the
syngas exits the burner holes.
This unit has almost three time the power of the 150.
See: http://www.youtube.com/watch?v=ySOkH0tP8LQ&feature=youtu.be
I am not still not happy with this premixing.
But note that when I turn off the premix value, a long (and highly
undesirable) diffusion flame is created.
This larger unit might be ideal for commercial applications, like this
brick kiln.
Thanks.
Paul
Thanks.
Paul Olivier
On Fri, Jun 14, 2013 at 4:12 PM, Energies Naturals C.B. <
energiesnaturals at gmx.de> wrote:
> 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" <ravermeer at telus.net> 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 ; stoves at lists.bioenergylists.org ; 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" <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
> > 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 <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)
> > Mobile: 090-694-1573 (in Vietnam)
> > Skype address: Xpolivier
> > http://www.esrla.com/
> >
> >
> >
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>
> --
> Energies Naturals C.B. <energiesnaturals at gmx.de>
>
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--
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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