[Stoves] Chimneys, rice husks [Ovens]

Sat Jun 15 04:40:45 CDT 2013

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
>>>>>>
>>>>>> _______________________________________________
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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/
>>>>
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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/
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