<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Alex, cc list adding Paul Olivier (not usually on this list)<div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>1. Nice new test. I am unaware of anyone else who has demonstrated premixing (except see below on one). Really good to see any work along these lines.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>2. Some comments:</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>a. It seems the flame diameter never exceeded about 3 inches. I think the flame doesn’t expand out to fill the full 6” max diameter because the pressure inside the flame is lower than outside. Lower because the number of particles goes down with both CO and H2. Ex: 2 H2 + O2 .>> 2 H2O (3 molecules goes to 2); same for the CO equation 2 CO + O2 >> 2 CO2.</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>b. It would be nice to see more in the vertical direction. Perhaps doing this with a glass cone or a set of small observational holes might give some more insights. I can conceive that your flame gets smaller in diameter as it rises (because all flames seem to do so).</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>c. There should be some data around on flame speed for TLUD-type gases. This 3” flame diameter number could be a way of learning more on the gas constituency. That is - why not a 2” or 4” flame when viewed from above?</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>d. There might be less than full mixing in your geometry; putting in some barriers ( a few inches of mineral wool?) to vary the time (or geometry) for mixing distances might be interesting. I remember reading once of variations in the length of Bunsen burners (which is different because CH4 + 2 O2 >> CO2 + 2 H2O give equality of 3 on each side. </div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>As an aside: with the LPG gases, propane (C3H8) and butane (C4H10), you have more particles after combustion. It looks like you could repeat this pyrolysis gas experiment with these three other gases - and we might learn something. (Remembering there would be temperature differences that would make it difficult to draw conclusions.)</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>e. Can you say a bit on the secondary air inlet. What total area? Any chance there is, or could be, a swirl? (to give more time for pre-mixing). Similar would be seeing the effect of changing the length of the riser, before getting to the flame.</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>f. If you had a 3” (or more) riser pipe diameter instead of 2”, would the flame have appeared at the secondary air holes? </div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>g. Not sure what you would learn from this, but what if the 2” riser suddenly expanded to 4” (no cone). My guess is that the short video would look about the same - about a 3” diameter flame as viewed from above. Another way of saying this is that the upward flowing pyrolysis gases flare out, and happen to be the right velocity when they are about a 3” diameter. (but you are avoiding eddies with your geometry.)</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>h. This last rambling thought makes me ask whether you can now (or soon) change both the primary and secondary air quantities? I think there is a possibility of some interesting changes. For instance, if you don’t have enough secondary, then the needed combustion air will have to flow downward in the cone. If you have a lot more secondary than you need (or could change its temperature), then maybe the 3” flame diameter would presumably change a little.</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>i. Same for primary air variations. As you point out there should be a change of gas composition that might tell us something new. At the present time, you have a fuel bed of 12” diameter. What is the fuel-bed height, and can you say more on the pellet (if pellet) size? How long to go through a run? If you are saving the char - how much?</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>3. What led you to try this experiment? (Were you expecting the very nice looking flame - and why?)</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>4. Pre-mixing could be advantageous for cooking (being such a nice looking flame) for health reasons (assuming you are dropping the count of 2.5 micron particulates). Have you tried to see what sort of “plaque” might be left on a cold surface above the flame?</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Another advantage for cook stoves is that you could get multiple burners going. (And it should be easy with smaller pipets each burner)</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>5. Paul Olivier and I talked over some TLUD experiments with pre-mixing several years ago (very different geometry). He didn’t like the results - so I am adding him to this message for comments.</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span></div><div class=""><br class=""></div><div class="">Thanks for the sharing - and (in advance) for any answer to my too-many questions above. Questions on your few sentences below are all covered above.</div><div class=""><br class=""></div><div class="">Ron<br class=""><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Sep 29, 2016, at 3:37 PM, alex english <<a href="mailto:aenglish444@gmail.com" class="">aenglish444@gmail.com</a>> wrote:</div></blockquote><blockquote type="cite" class=""><br class="Apple-interchange-newline"><div class=""><p dir="ltr" class="">Crispin,<br class="">
I don't know about the chemistry in the reaction zone, except that I would expect more hydrocarbon "tars" to remain with the char at lower temperatures.</p><p dir="ltr" class="">I am not currently tooled for combustion gas analysis. When I was, this flame would test at <100ppm CO and 8~10% CO2.</p><p dir="ltr" class="">Secondary air was not preheated beyond incidental ambient heat from the stove. it would be easy to get significant controllable preheat off the hot edge of the funnel.</p><p dir="ltr" class="">Alex</p>
<div class="gmail_extra"><br class=""><div class="gmail_quote">On Sep 29, 2016 1:01 PM, "Crispin Pemberton-Pigott" <<a href="mailto:crispinpigott@outlook.com" class="">crispinpigott@outlook.com</a>> wrote:<br type="attribution" class=""><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="EN-CA" link="blue" vlink="purple" class=""><div class=""><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class="">Thanks alex<u class=""></u><u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class=""><u class=""></u> <u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class="">If you run a higher superficial velocity I would expect to see the flame turn more to the blue, but it is already blue. Is it possible the H and all what we would normally see in the ‘flaming pyrolysis’ is taking place inside the bed? That would be pretty hot, no so?<u class=""></u><u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class=""><u class=""></u> <u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class="">Very interesting. Great video. What’s the CO/CO<sub class="">2</sub> ratio in that condition? <u class=""></u><u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class=""><u class=""></u> <u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class="">When the premixed air is added, what is the temperature going in? Harold thinks we should investigate that. I agree. I’ll ask Riaz at CAU.<font color="#888888" class=""><u class=""></u><u class=""></u></font></span></p><font color="#888888" class=""><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class=""><u class=""></u> <u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class="">Crispin<u class=""></u><u class=""></u></span></p></font><div class="quoted-text"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class=""><u class=""></u> <u class=""></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif" class=""><u class=""></u> <u class=""></u></span></p><p class="MsoNormal"><u class=""></u> <u class=""></u></p><p class="">No, but it is produced with a pyrolysis front at a temperature (500c ish) at the low end of normal for a TLUDs filled with wood pellets. There are some unanswered ( or demonstrated) questions here. To match burn rate with a higher py-fr-tp I need to use a smaller fuel chamber and increase the superficial velocity. This will perhaps produce a different gas composition. We'll see...<u class=""></u><u class=""></u></p><p class="">Alex<u class=""></u><u class=""></u></p><div class=""><p class="MsoNormal"><u class=""></u> <u class=""></u></p><div class=""><p class="MsoNormal">On Sep 29, 2016 9:00 AM, "Crispin Pemberton-Pigott" <<a href="mailto:crispinpigott@outlook.com" target="_blank" class="">crispinpigott@outlook.com</a>> wrote:<u class=""></u><u class=""></u></p><blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm" class=""><div class=""><div class=""><p class="MsoNormal" style="background:white"><span lang="EN-US" style="font-family:"Calibri",sans-serif;color:#1f497d" class="">Dear Alex<u class=""></u><u class=""></u></span></p></div><div class=""><p class="MsoNormal" style="background:white"><span lang="EN-US" style="font-family:"Calibri",sans-serif;color:#1f497d" class=""><u class=""></u> <u class=""></u></span></p></div><div class=""><p class="MsoNormal" style="background:white"><span lang="EN-US" style="font-family:"Calibri",sans-serif;color:#1f497d" class="">is that flame produced late in the pyrolysis? By that I means in a carbon 'evaporating' stage.<u class=""></u><u class=""></u></span></p></div><div class=""><p class="MsoNormal" style="background:white"><span lang="EN-US" style="font-family:"Calibri",sans-serif;color:#1f497d" class=""><u class=""></u> <u class=""></u></span></p></div><div class=""><p class="MsoNormal" style="background:white"><span lang="EN-US" style="font-family:"Calibri",sans-serif;color:#1f497d" class="">Thanks<u class=""></u><u class=""></u></span></p></div><div class=""><p class="MsoNormal" style="background:white"><span lang="EN-US" style="font-family:"Calibri",sans-serif;color:#1f497d" class="">Crispin <u class=""></u><u class=""></u></span></p></div></div></blockquote></div></div></div></div></div><br class="">______________________________<wbr class="">_________________<br class="">
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