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G'day Alexander,<br>
<br>
Thanks for your comments and suggestions! I agree that a "diffusion"
flame (with no primary air) may work better at low pressure and
possibly lower gas quality so I will add a comment to the
spreadsheet.<br>
<br>
All the best,<br>
HOOROO<br>
<pre class="moz-signature" cols="72">Mr Paul Harris BEng (Ag) (Melbourne)
Visitor at The University of Adelaide</pre>
<br>
On 22/05/2012 5:24 AM, Alexander Eaton wrote:
<blockquote
cite="mid:CAFmBdUCQpyYE4_JMwYwp0qMSk6aAB85k1g8L5rwq=izxL7w6Vg@mail.gmail.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
We have had many cases of poor air mixes generating biogas flames
that are not blue. I agree the "blue" does not necessarily mean
the most efficient combustion, but it is a good starting point. In
fact, I would add more value to the "observed" characteristics of
the flame as a good indicator of burner efficiency: If you can see
that the flame is blue (no yellow tips), stable, compact, does not
"float" above the ports, and you can smell that there is not
excessive odor, only very serious tests will give you much better
information. We realized this when we could basically "guess" the
results of our burning testing before the measured results were
calculated.
<div>
<br>
</div>
<div>Also, just a comment on the biogas burner information on the
wiki site: </div>
<div><br>
</div>
<div>First is it very well done and complete, however the
equations and relationships seem to fall apart under the low to
"no" pressure that we have in digesters in Latin America (eg,
non-dome-type). After a lot of trial and error, our "newest"
burner does not have any primary air mixing, our injector jet is
a bit larger than the calculations would suggest, and the burner
ports are about equal to that of LP Gas. This burner performs
much better than over ten iterations of other burners that have
better air mixing, and follow the normal calculations presented
in the literature. We believe this has everything to do with
nearly orders of magnitude difference in pressure between
tubular and fixed or floating dome systems. We are hoping to
publish these results shortly. In short, I would add an * to
any guides that allows for differences in burner designs for
systems that normally function at just a few mm of water column
pressure. </div>
<div><br>
</div>
<div>Best, </div>
<div><br>
A </div>
<div> <br>
<br>
<div class="gmail_quote">On Mon, May 21, 2012 at 12:11 PM,
Hoysall Chanakya <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:chanakya@astra.iisc.ernet.in" target="_blank">chanakya@astra.iisc.ernet.in</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Dear Dr
Tumwesige,<br>
Done well and is self contained.<br>
<br>
Would you like to supplement that the primary gas:air mixing
should be at<br>
stoichiometric ratio (calculated based on CH4 content) and
secondary air<br>
is at the burner ports (top openings). Further, methane
/biogas always<br>
burns with a blue flame and so a blue flame cannot be used
as an indicator<br>
for correct air-fuel ratio. At ideal conditions, the flame
burns with a<br>
hissing sound and the flame does not touch the burner tops
but burns 2-3mm<br>
above.<br>
best wishes<br>
Chanakya<br>
<br>
<br>
<br>
<br>
> Dear All,<br>
><br>
> I am writing a paper on biogas appliances, below is an
extract from the<br>
> paper.<br>
><br>
> All gas burners follow the same principle; the force
which drives the gas<br>
> and air into the burner is the pressure of gas in the
pipeline. A biogas<br>
> stove can have single or double burner with varying gas
consumption rates<br>
> ranging from 220 dm3 hr-1 to 450 dm3 hr-1 at standard
temperature and<br>
> pressure. This consumption rate results from the
pressure provided by the<br>
> biogas plant and the diameter of the inlet pipe. The
jet at the inlet of<br>
> the burner increases the gas speed, so producing a
draft that sucks<br>
> primary<br>
> air into the pipe. The primary air must be completely
mixed with the<br>
> biogas, and this is achieved by widening the pipe to a
minimum diameter,<br>
> which is in constant relation [JUS1] <#_msocom_1>
to the diameter of the<br>
> jet. The widening of the pipe again reduces the speed
of the gas. This<br>
> diffuse gas goes into the burner head. The burner head
is formed in such a<br>
> way as to allow equal gas pressure everywhere before
the gas/air mixture<br>
> leaves the burner through the orifices at a speed only
slightly above 0.25<br>
> ms-1, the specific flame speed of biogas. More oxygen
(secondary air) is<br>
> supplied by the surrounding air to enable final
combustion.<br>
> ------------------------------<br>
><br>
> [JUS1] <#_msoanchor_1>Specify what this constant
relationship is plus<br>
> reference<br>
> Please, is some one in position to provide more
information on the<br>
> highlighted section of the extract?<br>
><br>
> Thank you in advance,<br>
><br>
> Regards<br>
> --<br>
> Vianney Tumwesige<br>
> Director - Green Heat (U) Ltd [image: Picture]<br>
> P.O. Box 10235<br>
> Kampala-Uganda<br>
> 256 (0) 71 237 9889<br>
><br>
> "The more people are self sufficient in cooking fuel,
the more personal<br>
> and<br>
> financial freedom they have." - Emma Casson<br>
><br>
><br>
> <<a moz-do-not-send="true"
href="http://trustvianney.wordpress.com/" target="_blank">http://trustvianney.wordpress.com/</a>><br>
><br>
> --<br>
> This message has been scanned for viruses and<br>
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> believed to be clean.<br>
><br>
> _______________________________________________<br>
> Digestion mailing list<br>
><br>
> to Send a Message to the list, use the email address<br>
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href="mailto:Digestion@bioenergylists.org">Digestion@bioenergylists.org</a><br>
><br>
> to UNSUBSCRIBE or Change your List Settings use the web
page<br>
> <a moz-do-not-send="true"
href="http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org"
target="_blank">http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org</a><br>
><br>
> for more information about digestion, see<br>
> Beginner's Guide to Biogas<br>
> <a moz-do-not-send="true"
href="http://www.adelaide.edu.au/biogas/" target="_blank">http://www.adelaide.edu.au/biogas/</a><br>
> and the Biogas Wiki <a moz-do-not-send="true"
href="http://biogas.wikispaces.com/" target="_blank">http://biogas.wikispaces.com/</a><br>
><br>
><br>
<br>
<br>
--<br>
Dr. Hoysall Chanakya<br>
Centre for Sustainable Technologies<br>
(Assoc. Faculty at Centre for Infrastructure, Sustainable
Transport and<br>
Urban Planning (CiSTUP) and Centre for Contemporary Studies)<br>
Indian Institute of Science, Bangalore 560 012<br>
ph 91-80-2293 3046; fax-91 <a moz-do-not-send="true"
href="tel:80%202360%200683" value="+18023600683">80 2360
0683</a><br>
<br>
<br>
--<br>
This message has been scanned for viruses and<br>
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<br>
for more information about digestion, see<br>
Beginner's Guide to Biogas<br>
<a moz-do-not-send="true"
href="http://www.adelaide.edu.au/biogas/" target="_blank">http://www.adelaide.edu.au/biogas/</a><br>
and the Biogas Wiki <a moz-do-not-send="true"
href="http://biogas.wikispaces.com/" target="_blank">http://biogas.wikispaces.com/</a><br>
<br>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
Alexander Eaton<br>
Sistema Biobolsa<br>
IRRI-Mexico<br>
RedBioLAC<br>
<br>
Mex cel: (55) 11522786<br>
US cel: 970 275 4505<br>
<br>
<a moz-do-not-send="true" href="mailto:alex@irrimexico.org"
target="_blank">alex@irrimexico.org</a><br>
<a moz-do-not-send="true" href="mailto:alex@sistemabiobolsa.com"
target="_blank">alex@sistemabiobolsa.com</a><br>
<br>
<a moz-do-not-send="true" href="http://sistemabiobolsa.com"
target="_blank">sistemabiobolsa.com</a><br>
<a moz-do-not-send="true" href="http://www.irrimexico.org"
target="_blank">www.irrimexico.org</a><br>
<a moz-do-not-send="true" href="http://www.redbiolac.org"
target="_blank">www.redbiolac.org</a><br>
<br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Digestion mailing list
to Send a Message to the list, use the email address
<a class="moz-txt-link-abbreviated" href="mailto:Digestion@bioenergylists.org">Digestion@bioenergylists.org</a>
to UNSUBSCRIBE or Change your List Settings use the web page
<a class="moz-txt-link-freetext" href="http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org">http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org</a>
for more information about digestion, see
Beginner's Guide to Biogas
<a class="moz-txt-link-freetext" href="http://www.adelaide.edu.au/biogas/">http://www.adelaide.edu.au/biogas/</a>
and the Biogas Wiki <a class="moz-txt-link-freetext" href="http://biogas.wikispaces.com/">http://biogas.wikispaces.com/</a>
</pre>
</blockquote>
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