[Stoves] Chimneys, rice husks [Ovens]

Sat Jun 15 04:55:21 CDT 2013

Stephen,

Remember the context here: I have been talking about the direct combustion
of rice hulls.

Paul

On Sat, Jun 15, 2013 at 4:40 PM, Paul Olivier <paul.olivier at esrla.com>wrote:

> Stephen,
>
> Are you burning rice hulls at a temperature less than 450 C?
>
> Paul
>
>
> On Sat, Jun 15, 2013 at 4:10 PM, Stephen Joseph <joey.stephen at gmail.com>wrote:
>
>> I paul
>>
>> Not if you use the design with an inner fire box and an outer pyrolysis
>> chamber as is Mr Khois design.  In fact it is the main reason why I
>> recommended this design configuration and sizing to PED.
>>
>> We did a large research project with the Australia Government research
>> arm ACIAR to optimise the design.
>>
>> I have measurde the rice husk temperature in this outer chamber and it
>> stays pretty uniform at around 450C after the initial drying and
>> torrefaction phases.
>>
>>
>> Regards
>> Stephen
>>
>> On Sat, Jun 15, 2013 at 5:55 PM, Paul Olivier <paul.olivier at esrla.com>wrote:
>>
>>> But, Stephen, temperatures can rise above 900 C when burning rice hulls.
>>> If we operate at low temperatures (450 C) in burning rice hulls, are we
>>> not inevitably making a lot of smoke?
>>>  Even at relatively low average combustion temperatures, will there not
>>> be a tendency for hot zones to form within the combustor?
>>>
>>> Paul Olivier
>>>
>>>
>>> On Sat, Jun 15, 2013 at 2:44 PM, Stephen Joseph <joey.stephen at gmail.com>wrote:
>>>
>>>> All
>>>>
>>>> There has been a lot of work done on formation of crystobalite.  The
>>>> rate of formation is both a function of time and temerature
>>>>
>>>> If you have low temperatures (450c) and short times (<60 minutes)you
>>>> wont produce it.
>>>>
>>>> Mehta in India did a lot of work on this in the 80's and published a
>>>> book on rice husk ash cement if I remember correctly
>>>>
>>>> Regards
>>>> Stephen
>>>>
>>>>
>>>> On Sat, Jun 15, 2013 at 5:20 PM, Paul Olivier <paul.olivier at esrla.com>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
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Stoves mailing list
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>>>>>>> site:
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>>>>>>>
>>>>>>>
>>>>>>> ****
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Stoves mailing list
>>>>>>>
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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/ ****
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Stoves mailing list
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>>>>>>> site:
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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/
>>>>>
>>>>> _______________________________________________
>>>>> Stoves mailing list
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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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>>
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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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