<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Andrew and list:</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>This just to pick up on a few of your words from below: <i class="">"oxygen diffuses into the flame".</i></div><div class=""><i class=""><br class=""></i></div><div class=""><span class="Apple-tab-span" style="font-style: italic; white-space: pre;"> </span>This is accurate for most combustion. But with most TLUDs, the gases usually diffuse into the (secondary) oxygen. The result is "wispiness". There is a big difference on which is the larger outer medium. But the initial part of TLUD flames, where the flame is very close to the secondary air "hole" looks identical to a gas jet entering a body of air (but that is an illusion). So for the usual TLUDs, your phrase should be that the "pyrolysis gas diffuses into the flame".</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>The flame photo from Dr. Olivier that I forwarded is the traditional - gas jets entering air. This is NOT what most of us working with TLUDs have experienced.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I need to emphasize also that with methane combustion (which almost all of us can visualize), there is a different chemistry going on from combusting CO and H2. The former has the same number of particles [3] before and after combustion. The latter sees a reduction in particle number [3 down to two]</div><div class="">[CH4 + 2 O2 > CO2 + 2 H2O ; 2H2+O2 > 2 H2O; 2 CO +O2 > 2 CO2]; I don't see a relationship here to colors, but I think this pressure drop helps with TLUDS (that are leaving char behind).</div><div class=""><br class=""></div><div class="">Ron</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><br class=""><div><blockquote type="cite" class=""><div class="">On Jan 13, 2019, at 4:58 AM, Andrew Heggie <<a href="mailto:aj.heggie@gmail.com" class="">aj.heggie@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">On Sun, 13 Jan 2019 at 02:02, Ronal W. Larson <<a href="mailto:rongretlarson@comcast.net" class="">rongretlarson@comcast.net</a>> wrote:<br class=""><br class=""><blockquote type="cite" class=""> I see the word "Gasifiers" here a lot and want to emphasize instead the word "pyrolysis". This list has a sister group called "gasification" - that never has any discussion of making charcoal - only of consuming it.<br class=""></blockquote><br class="">The gasification list has dwindled worse than stoves, there have been<br class="">no posts since November.<br class=""><br class="">Anyway stoves isn't only about TLUD, so gasification of whole wood<br class="">happens in many stoves.<br class=""><br class="">I hope we can get more insight into this business of how rice hull<br class="">burners have a blue flame which only seems to happen when burning wood<br class="">if the gases and air are well mixed. The paper Alex linked to suggests<br class="">potassium has an effect in burning sooty particles, interestingly it<br class="">does point out that the amorphous parts burn out earlier than the<br class="">graphitic bits, which is what I would have expected as graphite<br class="">resists oxidation.<br class=""><br class="">It doesn't help with whether the higher ash content in rice husks<br class="">causes some interaction that leads to a bluer flame.<br class=""><br class="">I have a new wood burning room heater that has an insulated firebox<br class="">and a glass window. Once up to temperature and turned down it acts as<br class="">a pyrolyser and the flames are a lazy purple blue floating above the<br class="">hot wood, unfortunately my camera does not record what my eyes see<br class="">otherwise I would post a picture of the secondary air inlets combining<br class="">with the offgas.<br class=""><br class="">I have never seen any rice husks so cannot comment from personal experience.<br class=""><br class="">I understand how this happens in wood burning in that, when the flame<br class="">is diffuse, the burning takes place in two stages, firstly the<br class="">offgases dissociate and oxygen diffuses into the flame and combines<br class="">with hydrogen, then the carbon rich remainder rises in the heat and<br class="">radiates the characteristic yellow until it too combines with oxygen.<br class="">When the gases are premixed the reaction is more instantaneous and the<br class="">flame colour is bluer, often with a tinge of purple, which is more<br class="">characteristic of CO, H2 and potassium.<br class=""><br class="">You can often see this at the base of a candle flame, it is bluer and<br class="">if the wick shortens the flame becomes bluer.<br class=""><br class="">Andrew<br class=""><br class="">_______________________________________________<br class="">Stoves mailing list<br class=""><br class="">to Send a Message to the list, use the email address<br class=""><a href="mailto:stoves@lists.bioenergylists.org" class="">stoves@lists.bioenergylists.org</a><br class=""><br class="">to UNSUBSCRIBE or Change your List Settings use the web page<br class="">http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<br class=""><br class="">for more Biomass Cooking Stoves, News and Information see our web site:<br class="">http://stoves.bioenergylists.org/<br class=""><br class=""></div></div></blockquote></div><br class=""></body></html>