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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoPlainText>Paul<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>You just can't just make stuff up.<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>We talked about this years ago and the direction of gas flow is the first categorisation of devices. If you have included in your book that a TLUD which does not separate gas combustion from the gas generation is not a TLUD, even if it is, you will have to change the book. </p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>You can easily have a bottom lit downdraft stove that is not a gasifier. You can just as easily have one that is - depending on whether there is a pyrolysis zone that is very short of air and is creating gas at a rate that it cannot burn within the fuel bed. The gas escapes and burns below the grate. <o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>Wood can be burned in both modes in a downdraft fashion. It can just as well burn upwards in both modes. The difference between them is related to the air flow and O<sub>2</sub> availability in the gas generation zone, do you agree? Tom Reed proposes that the superficial velocity of the air dictates whether the system is a pyrolyser or a gasifier.<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>‘Any old fire' is not a characterisation of gas flow direction or the separation of generation from final combustion.<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>I would hold that there are three states: TLUD burning, TLUD gasification, and TLUD pyrolysation. Exactly the same divisions can be made for cross draft and downdraft combustors.<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>To my surprise I found out from Hirendra in India that he is making BLUD gasifiers - lots of them, and big too. I had never heard you talk about this layout. The fire is on the bottom and the MPF is rising through the fuel, the flow of air and gases is upwards. The fuel is continuously added from the top, and the ash is removed from the bottom. It runs continuously 24/7.<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>That is clearly a BLUD gasifier, as it does not produce charcoal so it is not a pyrolyser. Do I have that correct? I am following your lead on this. It is not a TLUD and it is refuellable which is a very big deal.<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>It means you could be having a micro-gasifier that is refuellable (from the top or just to the side), while creating gases that rise to a combustor above the top – clear separation from the gas generation zone. It does not have a hot char zone through which the gases rise. How is it we have not heard this system being described here before? He has been making them for years.<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'>Regards<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'>Crispin<o:p></o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText><span style='color:black'><o:p> </o:p></span></p><p class=MsoPlainText>Dear readers,<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>All readers are advised that some people insist on using a valid GASIFIER term of TLUD when referring to other types of fires because there is ignition at the top of a fuel pile and the air flow is <o:p></o:p></p><p class=MsoPlainText>upward. And they do this without regard to the GASIFIER structure that <o:p></o:p></p><p class=MsoPlainText>allows the creation of the gases to be separate in time and space from <o:p></o:p></p><p class=MsoPlainText>the burning (or other usage) of the created gases. The creation and <o:p></o:p></p><p class=MsoPlainText>the burning of the gases can be very close, but they CAN be separated. <o:p></o:p></p><p class=MsoPlainText>For example, the top flame (the secondary combustion) can be extinguished in a TLUD gasifier (but not in just any old bucket or open fire).<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Paal Wendelbo observed the Norwegian resistance fighters having top <o:p></o:p></p><p class=MsoPlainText>lighting of open campfires, and they were not using gasifier devices. <o:p></o:p></p><p class=MsoPlainText>40 years later he contained that pyrolysis and gas burning processes inside metal cylinders and had the start of what is today called TLUD gasifiers.<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Today, after 30 years of development of TLUD stoves and other true micro-gasifiers that now have respectable recognition, it is becoming trendy to call other things TLUDs when they are not or are mere shadows <o:p></o:p></p><p class=MsoPlainText>of what is involved with gasifier stoves. There are no "terminology <o:p></o:p></p><p class=MsoPlainText>police" or copyrights on TLUD. Readers need to be aware of the details <o:p></o:p></p><p class=MsoPlainText>of the actual operations, regardless of what it is being called.<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Readers are encouraged to use as a reference the book on Micro-gasification.... by Christa Roth (GIZ publisher) and my article "Micro-gasification Terminology...", both of which are available in the <o:p></o:p></p><p class=MsoPlainText>Quick Picks list on my website <a href="http://www.drtlud.com"><span style='color:windowtext;text-decoration:none'>www.drtlud.com</span></a><o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>I did not invent TLUD gasifiers, but I did give them that name 10 years <o:p></o:p></p><p class=MsoPlainText>ago. People can use the words top lit and up draft to describe other <o:p></o:p></p><p class=MsoPlainText>things, but the acronym TLUD should appropriately refer to a reasonably well defined TYPE OF GASIFIER DEVICE, most specifically as a cookstove or char-maker. Use of that TLUD designation for other devices is a form of mimicry and getting on a bandwagon, or worse, which is just to make confusion.<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Dr TLUD<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p></div></body></html>