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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoPlainText>Dear Kevin<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Just on the point of non-uniform fuel. One way to deal with non-uniform fuel is to make the combustion chamber larger. It seems to have a good effect, making things burn more evenly. It does not necessarily produce the same level of control (via the primary air), however.<o:p></o:p></p><p class=MsoPlainText>Fuel particle size in Mongolia is highly variable – something I have been trying to get them to reconsider for 5 years. However, it is not all ‘lost’ if there is high variability. <o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>I noticed that the larger the gaps between fuel particles, the more likely it is to go into a condition of a self-accelerating retort. This means it will continue to produce heat in an uncontrollable manner (operating at the limit of its ability to generate combustible gases). <o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>If the combustion conditions are such that the fuel in use tends to do that, using larger pieces will to an extent control the tendency. While it is perhaps obvious that some small fuel pieces will keep a large single chunk of fuel burning, the opposite is also true. Cecil notes that people burning sawdust in a canister with ‘under air’ supplied through a side hole, sometimes use a pair of small sticks inserted through the hole to keep a flame going in the very much small sawdust. This duel-fuel approach is far cleaner burning and more manageable than sawdust alone.<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Regards<o:p></o:p></p><p class=MsoPlainText>Crispin<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p></div></body></html>