Crispin,<br><br>Primary air is needed for the gasification or pyrolysis process.<br>Secondary air is needed to burn the gas.<br>The secondary air could be mixed with the gas prior to combustion.<br>But in this case, there cannot be a 100% premix.<br>
Tertiary air is needed to complete the combustion.<br><br>In the Belonio burner there is no premixing.<br>What happens instead is that the gas exit through two staggered sets of hole along the periphery of the reactor lid.<br>
With the burner housing I get secondary air to enter horizontally <br> and mix with the gas exiting the burner holes along the periphery of the lid.<br>This takes place in an area protected from the wind, and over a fairly large surface area.<br>
At this point most of the gas is burned.<br><a href="http://www.youtube.com/watch?v=WXZvvoxCm1g">http://www.youtube.com/watch?v=WXZvvoxCm1g</a><br><br>But there is still a small diffusion tail.<br>This tail has also to be protected from a rush of excess air and from random air movement.<br>
Here only a small gap is provided to allow for the entry of tertiary air.<br><br>So above the burner and burning housing there is small chamber that sits right under the pot.<br>The entry of tertiary air into this chamber takes place through a small gap at the bottom.<br>
Previously the dome was this chamber.<br>Now only a short section of tube is needed.<br><br>Thanks.<br>Paul Olivier<br><br><br><br><div class="gmail_quote">On Sat, Mar 17, 2012 at 6:43 AM, Paul Olivier <span dir="ltr"><<a href="mailto:paul.olivier@esrla.com">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">See comments.<br><br><div class="gmail_quote"><div class="im">On Fri, Mar 16, 2012 at 11:56 PM, Crispin Pemberton-Pigott <span dir="ltr"><<a href="mailto:crispinpigott@gmail.com" target="_blank">crispinpigott@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear Paul A<br>
<br>
I think quite a bit more experimentation is needed before copying the top<br>
end of Alexis' burner. </blockquote></div><div><br>In this sentence, you use the word "before".<br>Why not skip the "before: and begin experimenting "with" the Belonio burner?<br> </div><div class="im">
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
The evolution is that it was not a premixed flame and<br>
the structure was built with that in mind. The change to a premixed flame<br>
was not matched by a change in the structure. </blockquote></div><div><br>I do not understand what you are saying here.<br> </div><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class="im">
The result is that there is a<br>
very high excess air rate passing through the underside and emerging by the<br></div>
pot. This has the effect of heating a lot of air and lowering the gas<br>
temperature beside the pot.<br></blockquote><div><br>Why do you think that there is necessarily a "very high excess air rate"?<br>I would agree that the Belonio burner all by itself might have a high excess air rate.<br>
That is why I designed a housing around the burner,<br> and this housing is surely not the best that could be done in this case.<br>After the housing there is still another part needed to limit excess air.<br><br>Of course one could design a true premix burner and situate this on top of the reactor.<br>
Here a distinction would be made between the lid of the gasifier and the burner.<br>The two would no longer be the same.<br>But air entrainment before burning the gas requires pressure,<br> and pressure requires gaskets that do not leak,<br>
since gaskets that leak are quite dangerous.<br>I suppose that pressure has to be controlled with a high degree of precision.<br>This might call for a fan with a good speed regulator.<br>But with a fan, the unit is no longer natural draft.<br>
<br>You are right: with a lot of excess air, combustion might be good, but heat transfer might be poor.<br>The dome looked so promising from the point of view of limiting excess air.<br>And now without the dome, I am testing the design of still another part<br>
that limits excess air and protects the flame from wind.<br><br>Thanks.<span class="HOEnZb"><font color="#888888"><br>Paul Olivier<br><br><br></font></span></div><div><div class="h5"><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
I feel that a 30% improvement in heat transfer efficiency can be achieved by<br>
addressing this issue.<br>
<br>
I have noticed that stove builders fall roughly into two groups: those who<br>
build high neat transfer efficiency stove bodies but with mediocre<br>
combustion, and those who make really good combustion but neglect the detail<br>
of getting good heat transfer. In some cases there is a sort of blind<br>
adherence to the idea that a fuel is 'clean' and there is no need for<br>
either. 'Clean burning means efficient,' which is nonsense.<br>
<br>
We should all be paying a lot of attention to both aspects of stove<br>
building: efficient combustion and efficient heat transfer. One does not<br>
automatically derive from the other.<br>
<br>
Regards<br>
Crispin<br>
<br>
<br>
-----Original Message-----<br>
From: <a href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">stoves-bounces@lists.bioenergylists.org</a><br>
[mailto:<a href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">stoves-bounces@lists.bioenergylists.org</a>] On Behalf Of Paul S.<br>
Anderson<br>
Sent: Friday, March 16, 2012 6:07 PM<br>
To: Discussion of biomass cooking stoves; Paul Olivier<br>
Cc: <a href="mailto:zong@ilstu.edu" target="_blank">zong@ilstu.edu</a>; Belonio - Philippines; Corey Berman; Hugh McLaughlin;<br>
Bob Fairchild; Alexis; Chua He<br>
Subject: [Stoves] Belonio burner top on TLUD stoves was Re: radiant heat<br>
capture, total heat measurement<br>
<br>
Dear all,<br>
<br>
Paul Olivier commented: (full message is still below, with link to a<br>
photo)<br>
<br>
> ..... which has always led me to wonder why the Belonio burner hole<br>
> pattern was not adopted on natural draft units.<br>
> If a burner housing were added, I think the unit I experimented with<br>
> would work much better.<br>
<br>
Paul O. raises an excellent point. I think that the moderate complexity of<br>
the Belonio hole pattern and secondary air inlet (contrasted to simple<br>
concentrator hole) has kept me and probably most others from experimenting<br>
with it. Perhaps we incorrectly associated it too much with the forced air<br>
(Fan Assisted = FA) aspects of Belonio's rice husk gasifiers.<br>
<br>
Very little is known about the tops of TLUDs except that some amount of<br>
constriction is needed to force the mixing of air and gases.<br>
<br>
I hope that the engineers (such as Bob Fairchild and student<br>
engineers) and others who are now working on TLUD stove issues will<br>
seriously consider the Belonio top and related enhancers of combustion of<br>
the gases.<br>
<br>
Paul (Paul A.; not to be confused with Paul O.)<br>
--<br>
Paul S. Anderson, PhD<br>
Known to some as: Dr TLUD Doc Professor<br>
Phone (USA): 309-452-7072 SKYPE: paultlud Email: <a href="mailto:psanders@ilstu.edu" target="_blank">psanders@ilstu.edu</a><br>
<a href="http://www.gtz.de/de/dokumente/giz2011-en-micro-gasification.pdf" target="_blank">www.gtz.de/de/dokumente/giz2011-en-micro-gasification.pdf</a> (excellent ref.)<br>
My website specific for TLUD information: <a href="http://www.drtlud.com" target="_blank">www.drtlud.com</a> = <a href="http://www.DrTLUD.com" target="_blank">www.DrTLUD.com</a><br>
<br>
<br>
Quoting Paul Olivier <<a href="mailto:paul.olivier@esrla.com" target="_blank">paul.olivier@esrla.com</a>>:<br>
<br>
> Kevin,<br>
><br>
> You say:<br>
> *# OK!! A 50% reduction in boiling time is very significant.<br>
> What can you now tell us that will enable us to apply it to other stoves<br>
> and combustion conditions?*<br>
><br>
> I once did an experiment in which I made the 150 Belonio about half its<br>
> original height.<br>
> I then filled it with chunks of wood and put a Belonio burner on top.<br>
> This was a natural draft unit without a fan.<br>
> This is what it looked like:<br>
<br>
> <a href="http://dl.dropbox.com/u/22013094/150%20Burner/Image2097.jpg" target="_blank">http://dl.dropbox.com/u/22013094/150%20Burner/Image2097.jpg</a><br>
<br>
> But looking back on this, I see that there were so many problems with this<br>
> burner,<br>
> even aside from the fact that it had no burner housing.<br>
><br>
> You raise an interesting question, though, which has always led me to<br>
wonder<br>
> why the Belonio burner hole pattern was not adopted on natural draft<br>
units.<br>
> If a burner housing were added, I think the unit I experimented with would<br>
> work much better.<br>
> The central problem that I see with a natural draft unit is an uneven<br>
> upward flow of primary air.<br>
> At times too much CO2 is created, and some burner holes lose their flames.<br>
> Also I would imagine that the inlet of primary air has to be strictly<br>
> control to get a consistent outlet of gas at the burner.<br>
><br>
> A natural draft TLUD is very complicated,<br>
> and I truly marvel at those who get them to work on such a broad variety<br>
> of fuels.<br>
><br>
> Thanks.<br>
> Paul<br>
><br>
> Thanks.<br>
> Paul<br>
<br>
<br>
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</blockquote></div></div></div><br><br clear="all"><div class="HOEnZb"><div class="h5"><br>-- <br>Paul A. Olivier PhD<br>27C Pham Hong Thai Street<br>Dalat<br>Vietnam<br><br>Louisiana telephone: 1-337-447-4124 (rings Vietnam)<br>
Mobile: 090-694-1573 (in Vietnam)<br>Skype address: Xpolivier<br>
<a href="http://www.esrla.com/" target="_blank">http://www.esrla.com/</a><br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>Paul A. Olivier PhD<br>27C Pham Hong Thai Street<br>Dalat<br>Vietnam<br><br>Louisiana telephone: 1-337-447-4124 (rings Vietnam)<br>Mobile: 090-694-1573 (in Vietnam)<br>
Skype address: Xpolivier<br><a href="http://www.esrla.com/" target="_blank">http://www.esrla.com/</a><br>