<div dir="ltr"><div><div>But, Stephen, temperatures can rise above 900 C when burning rice hulls.<br></div>If we operate at low temperatures (450 C) in burning rice hulls, are we not inevitably making a lot of smoke?<br></div>
<div>Even at relatively low average combustion temperatures, will there not be a tendency for hot zones to form within the combustor?<br></div><div><br></div>Paul Olivier<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">
On Sat, Jun 15, 2013 at 2:44 PM, Stephen Joseph <span dir="ltr"><<a href="mailto:joey.stephen@gmail.com" target="_blank">joey.stephen@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
All<div><br></div><div>There has been a lot of work done on formation of crystobalite. The rate of formation is both a function of time and temerature</div><div><br></div><div>If you have low temperatures (450c) and short times (<60 minutes)you wont produce it.</div>
<div><br></div><div>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</div><div><br></div><div>Regards</div><div><span class="HOEnZb"><font color="#888888">Stephen</font></span><div>
<div class="h5"><br><br><div class="gmail_quote">
On Sat, Jun 15, 2013 at 5:20 PM, Paul Olivier <span dir="ltr"><<a href="mailto:paul.olivier@esrla.com" target="_blank">paul.olivier@esrla.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr"><div><div><div>Tom,<br><br></div>I found this news report:<br><a href="http://www.ipsnews.net/2009/10/thailand-renewable-energy-not-so-clean-and-green-after-all/" target="_blank">http://www.ipsnews.net/2009/10/thailand-renewable-energy-not-so-clean-and-green-after-all/</a><br>
</div><div>Not such a nice story.<br></div>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.<br><br></div>Paul<br></div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Sat, Jun 15, 2013 at 1:10 PM, Paul Olivier <span dir="ltr"><<a href="mailto:paul.olivier@esrla.com" target="_blank">paul.olivier@esrla.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr"><div><div>Tom,<br><br>I have read in many articles that cristobalite can form at temperatures of about 900 C.<br><a href="http://www.jicosh.gr.jp/old/niih/en/indu_hel/2004/pdf/42-2-24.pdf" target="_blank">http://www.jicosh.gr.jp/old/niih/en/indu_hel/2004/pdf/42-2-24.pdf</a><br>
In burning rice hulls, temperatures can easily exceed 900 C.<br>If cristobalite forms and is breathed in, human health is severely impacted: silicosis, tuberculosis, cancer and so forth.<br><br><i>Silica (SiO2) is a constituent of the ash produced by the combustion process. Different<br>
types of biomass fuels contain different quantities of silica. The International Agency for<br>Research on Cancer has classified silica as a human carcinogen. Long term inhalation<br>of airborne silica particulates can cause lung cancer or other related health problems.<br>
As rice hull ash contains high levels of silica (~15%), its use as a biomass fuel<br>presumably increases the risk of developing silicosis-related illnesses, and care should<br>be used in handling the ash.</i><br><a href="http://www.reap-canada.com/online_library/IntDev/id_eco_sugarcane/7%20Strategies%20for.pdf" target="_blank">http://www.reap-canada.com/online_library/IntDev/id_eco_sugarcane/7%20Strategies%20for.pdf</a><br>
<br><i>Silica (SiO2) is the main mineral component of rice husk ash (RHA) (85-90 per cent). It carries serious health risks, particularly to the<br>respiratory system.</i> <br><a href="http://www.dhf.uu.se/pdffiler/cc7/cc7_web_art4.pdf" target="_blank">http://www.dhf.uu.se/pdffiler/cc7/cc7_web_art4.pdf</a><span></span><span></span><br>
<br></div>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. <br><span><font color="#888888"><br>
</font></span></div><span><font color="#888888">Paul<br></font></span></div><div><div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sat, Jun 15, 2013 at 11:18 AM, Tom Miles <span dir="ltr"><<a href="mailto:tmiles@trmiles.com" target="_blank">tmiles@trmiles.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div link="blue" vlink="purple" lang="EN-US"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Paul,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">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?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Tom <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Stoves [mailto:<a href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">stoves-bounces@lists.bioenergylists.org</a>] <b>On Behalf Of </b>Paul Olivier<br>
<b>Sent:</b> Friday, June 14, 2013 8:56 PM<br><b>To:</b> JJ Claire; Discussion of biomass cooking stoves<br><b>Subject:</b> Re: [Stoves] Chimneys, rice husks [Ovens]<u></u><u></u></span></p><div><div><p class="MsoNormal">
<u></u> <u></u></p><div><div><div><div><p class="MsoNormal" style="margin-bottom:12.0pt">JJ,<u></u><u></u></p></div><p class="MsoNormal">I would not recommend that you burn rice hulls ir rice straw.<u></u><u></u></p></div>
<p class="MsoNormal" style="margin-bottom:12.0pt">In many cases this is quite dangerous.<u></u><u></u></p></div><p class="MsoNormal">Paul<u></u><u></u></p><div><div><div><div><div><div><p class="MsoNormal" style="margin-bottom:12.0pt">
<u></u> <u></u></p><div><p class="MsoNormal">On Sat, Jun 15, 2013 at 9:40 AM, JJ Claire <<a href="mailto:pugoclaire@yahoo.com" target="_blank">pugoclaire@yahoo.com</a>> wrote:<u></u><u></u></p><div><div><div><p class="MsoNormal">
<span style="font-size:14.0pt;font-family:"Bookman Old Style","serif"">Greetings one and all,<u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">I visit the Philippines often and usually stay about six months a year. <u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">I often use a rice hull stove. I would like to get a plan to build a <u></u><u></u></span></p></div>
<div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">concrete stove. I am also wondering if there is such a thing as building <u></u><u></u></span></p></div>
<div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">an 'oven' using cement and/or concrete? I would like to build one, <u></u><u></u></span></p></div>
<div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">a white model if possible, [vice a black model], if such a plan is <u></u><u></u></span></p></div><div>
<p class="MsoNormal">
<span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">available and if the technology would be practical. We have a <u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">lot of rice hulls and not all that much firewood. <u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">I would be open to heating the oven with firewood and then <u></u><u></u></span></p></div><div><p class="MsoNormal">
<span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">maintaining the heat level with or by burning rice hulls. I have<u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">a lot of rice hulls and want to make the best use of the hulls.<u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">I currently use the wood ashes to make lye so I can make soap, <u></u><u></u></span></p></div><div>
<p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">but I have not used any ashes from rice hulls to make lye. I<u></u><u></u></span></p></div><div><p class="MsoNormal">
<span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">wonder if making lye with rice hulls is possible.<u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">The rice hull stoves we use are sort of a metal pail with a wire rack. <u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">I am looking for a stove, hopefully one that is hot, medium and cool, <u></u><u></u></span></p></div>
<div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">for cooking with rice hulls over a long number or years. <u></u><u></u></span></p></div><div><p class="MsoNormal">
<span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">On our island, rice hulls are still burned to 'get rid of them', and <u></u><u></u></span></p></div><div><p class="MsoNormal">
<span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">believe it or not, rice straw is still burned. I often ask neighboring<u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">farmers to bring me their straw and provide them a small bit of <u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">cash for doing so. We use the rice straw for making compost.<u></u><u></u></span></p></div><div>
<p class="MsoNormal">
<span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">We add some rice hulls to the compost. Most of the rice hulls<u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">are burned for fuel to cook with. We add the char from the cooking<u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">process to the garden. I am wondering if we are making the best<u></u><u></u></span></p></div><div>
<p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">use of the rice hulls and if the plans I am speaking of by post <u></u><u></u></span></p></div><div><p class="MsoNormal">
<span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">are available. <u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">Please inform, I am open to suggestions and direction.<u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">Blessings,<u></u><u></u></span></p></div><div><p class="MsoNormal"><span style="font-size:14.5pt;font-family:"Bookman Old Style","serif"">JJ<u></u><u></u></span></p>
</div><div><p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Bookman Old Style","serif""> <u></u><u></u></span></p></div><div><div><div><p class="MsoNormal"><b><span style="font-family:"Arial","sans-serif"">From:</span></b><span style="font-family:"Arial","sans-serif""> "<a href="mailto:ajheggie@gmail.com" target="_blank">ajheggie@gmail.com</a>" <<a href="mailto:ajheggie@gmail.com" target="_blank">ajheggie@gmail.com</a>><br>
<b>To:</b> Discussion of biomass cooking stoves <<a href="mailto:stoves@lists.bioenergylists.org" target="_blank">stoves@lists.bioenergylists.org</a>> <br><b>Sent:</b> Friday, June 14, 2013 5:02 PM<br><b>Subject:</b> Re: [Stoves] Chimneys, rice husks</span><u></u><u></u></p>
</div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><br>[Default] On Fri, 14 Jun 2013 17:37:30 -0400,"Crispin<br>Pemberton-Pigott" <<a href="mailto:crispinpigott@gmail.com" target="_blank">crispinpigott@gmail.com</a>> wrote:<br>
<br>>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.<br>
<br>We have used them on pellet stoves (which have their own id fans) to<br>limit draught on an insulated ss chimney that rose through 4 floors. I<br>wasn't entirely happy with the idea as it raised the possibility of<br>
the boiler room getting combustion products if the seal wasn't good, I<br>would have been happier if the air was sucked from outside. In fact<br>there was subsequently a problem but this was down to poor<br>maintenance.<br>
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