[Stoves] Chimneys, rice husks [Ovens]

Sat Jun 15 11:13:23 CDT 2013

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-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 <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%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 <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

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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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-- 
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/
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