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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Dear Darren<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I think you are going to have a couple of problems with the layout as drawn and they are solvable.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Let’s look at them all:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The restricted height at the entrance of the combustion area is probably the right height, but that is for limiting the amount of fuel that can fall onto the grate further in.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The grate needs to extend into the whole area under the combustion zone or else it will fill up with ash and you don’t have a way to get it out. The grate is correctly placed, perhaps a little steep but that can be altered. Char and ash will fall forward (as it should) but end up in the bottom of the combustion area.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The constriction you describe well on the side is going to catch some of the char and ash and might (or not) create a bridging problem. You can address that if it happens.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>4.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The purpose of getting the grate under all the horizontal area solves two things: it allows a lot of controllable air to reach the far end of the grate where there will always be less fuel. That means air gets through and effectively becomes secondary air. If you make the grate shakeable, you can clear the ash but you will need to have it stop at a vertical or inclined surface or the bottom will get blocked.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>5.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>We are having pretty much the same layout but the restriction is above the grate about 100mm. This allows the grate to carry enough fuel and still have all the gases and smoke and flames come together above the fuel. <o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>6.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>We start the fire by placing some fuel on the grate, extending into the part below the combustion area then top-light in the combustion area. The fire works its way back to the fuel hopper it the top is left open. Then when it is well established, close the hopper and vary the air with the controller you indicated.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>7.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The key change is the extension of the grate, perhaps at a lower angle. We are using 15-20 degrees but there is nothing magic in that.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>8.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I have attached a drawing of the GIZ 7.1 combustion chamber that worked very well using all the principles mentioned. Note the angled piece on the right. This protects the grate from becoming blocked from movement by trapping something between it and the wall, when shaken. <o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>9.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Note the constriction above the left side of the grate. It is 100 x 80mm. As you look at the side view drawing, the grate is 155 deep. That means the moving part is about 260 x 155.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0mm 0mm 0mm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> stoves-bounces@lists.bioenergylists.org [mailto:stoves-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Darren Hill<br><b>Sent:</b> 21 February 2011 20:40<br><b>To:</b> Discussion of biomass cooking stoves<br><b>Subject:</b> Re: [Stoves] Building my Heat / cook stove.<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hello Crispin,<br><br>The bleed is at top bypassing the need for gases to go down past the heat exchanger.<br><br>Secondary air is flowing in through some 20mm x 20mm internal diameter square section tubing. Is this enough or do I need more? Another 20mm x 20mm square section tube? More?<br><br>I've attached another diagram which shows things as they are currently planned/progressing.<br><br>Looking at this diagram. Are you saying to have some of the grate to the left of the red line I've drawn on the diagram?<br><br>Currently this is the thinnest point (or bottle neck, or throat) and has a vertical ceramic slab either side so that this 'throat' is not the full width of the hopper. Extending the grate further to the left will, in effect, increase the area of the thinnest point. I currently plan to have the lowest part of the grate level with the bottom of the ceramic block (that is the floor of the combustion chamber) so it is away from the thinnest/hottest area.<br><br>Is it best to shift the grate to the left? <br>If so what % of the grate left of the red line?<br>Should I also raise the grate so that the its level with the top of the ceramic block that is the floor of the combustion chamber?<br><br>I'm working on the stove today and tomorrow. Going to build the air tight doors today.<br><br>Best<br><br>Darren <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>