[Stoves] Chimneys, rice husks [Ovens]

Sat Jun 15 02:20:33 CDT 2013

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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>> ****
>>
>>
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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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