[Stoves] Chimneys, rice husks [Ovens]
Tom Miles
tmiles at trmiles.com
Sat Jun 15 11:49:29 CDT 2013
>From my experience with industrial rice husk burning in Thailand I suspect
that it is likely that a health hazard is not from the combustion process
itself, where emissions are controlled by control devices, but from the
management of the fuel and the ash which can create what are called fugitive
emissions. Devices used at plants like AT Power are designed to remove fine
particulates. If their smoke stack is in compliance then that is not the
problem. (If it is out of compliance then the problem may be corruption, not
technology.) We don't have similar complaints from communities in the US
where rice husks are burned at the same scale but where fugitive emissions
are tightly regulated. In one case fugitive cristobalite silica was an issue
for the ash handling system but that was resolved.
Testing combustion and fugitive emissions could determine if a household
that burns a few kg per day of husks for cooking is going to create a health
hazard similar to an uncontrolled plant that burns 20-30 tons per hour. As
far as I know that has not been done.
If ash or char from burning rice husks in domestic or industrial devices is
determined to be hazardous then it should be appropriately identified,
labeled, and handled. Since rice husk is perhaps the largest potential
domestic fuel source in a desperate world it is likely that survival will be
chosen over potential health risks. We can't abandon rice husk as a fuel. We
have to find ways to make it work. TLUDs may be part of the answer.
Tom
From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Richard Stanley
Sent: Saturday, June 15, 2013 9:13 AM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Chimneys, rice husks [Ovens]
Paul,
>From the side lines,. that appears to be solid research. Aside from a few
bribe-oriented complaintants, most report what you are concerned about and
the partners and sources of funding for the groups doing the reportage are
good as well. I guess then it is a question of whether or not binding and
blending of the rice hulls with other biomass effectively retards
cristobalite formation -- or has no effect on it--or enhances it, for that
matter.
Richard Stanley
www.legacyfound.org
On Jun 15, 2013, at 12:20 AM, Paul Olivier wrote:
Tom,
I found this news report:
http://www.ipsnews.net/2009/10/thailand-renewable-energy-not-so-clean-and-gr
een-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 <paul.olivier at esrla.com>
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%20Strate
gies%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 <tmiles at trmiles.com> 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:stoves-bounces at lists.bioenergylists.org] 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 <pugoclaire at yahoo.com> 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: "ajheggie at gmail.com" <ajheggie at gmail.com>
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
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" <crispinpigott at gmail.com> 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
stoves at lists.bioenergylists.org
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
stoves at lists.bioenergylists.org
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
stoves at lists.bioenergylists.org
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
stoves at lists.bioenergylists.org
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/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20130615/ee20f332/attachment.html>
More information about the Stoves
mailing list