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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The issues here are similar to those experienced with any burner. The majority of combustible gases have rather restricted behaviors when it comes to flame propagation speed and pressure build-up (acetylene and a few others are notable exceptions). Air and natural gas is mixed in a burner, but rarely are there backfires (edging toward lean combustion) and if there are the pressure rise is rarely precipitous.<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'>Naturally, it pays to be cautious, so a determined set of tests at various combustible ratios may be comforting. But this is the same fuel that we wish to encourage to burn by compressing it 20-fold and advancing an ignition spark 30-or-more degrees. If explosion or conflagration were really a risk, then we should be so lucky!<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'>Mark<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><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Gasification [mailto:gasification-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>jim mason<br><b>Sent:</b> Monday, December 10, 2012 12:45 PM<br><b>To:</b> Discussion of biomass pyrolysis and gasification<br><b>Subject:</b> Re: [Gasification] filtration options and their varying discontents<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On Mon, Dec 10, 2012 at 12:41 PM, David G. LeVine <<a href="mailto:dlevine@speakeasy.net" target="_blank">dlevine@speakeasy.net</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal>On 12/09/2012 10:34 PM, jim mason wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>other than the explosive risk<o:p></o:p></p></blockquote><p class=MsoNormal><br>There is an interesting question here:<br><br>Is there an explosion risk if the gasses have not been diluted by the atmosphere?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>well, in principle, the gas should not be diluted with air during typical operation, and thus no explosion problem. you are correct. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>the problem is typical operation is variable. during start up you always go through a stoich point as you move air out of the system and progressively make gas. even if you leave the system full of gas on shut down, start up in the reactor can pass lots of air until things get up to temp again. this can easily result in a combustible mixture in the system.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>we've found this to be a fairly significant operational reality that needs to be addressed for regular users. similar for the impact of backfires from the engine igniting the intake stream. while things are "usually" ok, the marginal events can be quite, umm, compelling . . . we've started adding more pressure relief points where typically not needed to cover these outliers. we're also looking to add a flame arrestor right at the manifold to prevent backfires propagating.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>again, you never use these during typical operation. somewhat like an ESP shouldn't cause any problems during regular operation. it is the outliers that are of concern. when you start running these systems regularly, you tend to find all the outliers. and the ones you don't find in house, those out in the fields certainly will.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>j<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><p class=MsoNormal>Let's start with gasoline, if we evacuate a bell jar and inject enough gasoline so there is a layer of liquid gasoline on the floor or in a pan, and we generate a hot arc 1/2" above the gasoline, will there be an explosion? The correct answer is "only if there is an air leak." <br><br>Without an air leak, there will be no oxidizer, fire (or explosions) require three things: Fuel, Oxidizer and Ignition. Fuel is gasoline (in this case), Ignition is the spark, but where is the oxidizer? <br><br>If woodgas has excess oxidizer as it exits the reaction zone, it simply burns off the extra gas. So, unless there is an air leak, the reaction can not occur. However, if there is an air leak in _any_ fuel system, there will be severe problems.<br><br>Dave 8{)<span class=hoenzb><span style='color:#888888'><o:p></o:p></span></span></p><div><p class=MsoNormal style='margin-bottom:12.0pt'><span style='color:#888888'>-- <br><br><em>"The first method for estimating the intelligence of a ruler is to look at the men he has around him."</em> <br>Niccolo Machiavelli</span><em><o:p></o:p></em></p><p class=MsoNormal align=center style='text-align:center'><i><span style='color:#888888'>NOTE TO ALL:</span></i><o:p></o:p></p><p class=MsoNormal><i><span style='color:#888888'><br><em>When forwarding emails, please use only "Blind Carbon Copy" or "Bcc" for all recipients. Please "delete" or "highlight & cut" any forwarding history which includes my email address! It is a courtesy to me and others who may not wish to have their email addresses sent all over the world! Erasing the history helps prevent Spammers from mining addresses and viruses from being propagated. </em></span></i><span style='color:#888888'><br><br>THANK YOU! <o:p></o:p></span></p></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><br>_______________________________________________<br>Gasification mailing list<br><br>to Send a Message to the list, use the email address<br><a href="mailto:Gasification@bioenergylists.org">Gasification@bioenergylists.org</a><br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br><a href="http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org" target="_blank">http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org</a><br><br>for more Gasifiers, News and Information see our web site:<br><a href="http://gasifiers.bioenergylists.org/" target="_blank">http://gasifiers.bioenergylists.org/</a><o:p></o:p></p></blockquote></div><p class=MsoNormal><br><br clear=all><o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>-- <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><br><br>Jim Mason<br>Website: <a href="http://www.whatiamupto.com" target="_blank">http://www.whatiamupto.com</a><br>Current Projects:<br> - Gasifier Experimenters Kit (the GEK): <a href="http://www.gekgasifier.com" target="_blank">http://www.gekgasifier.com</a><br> - Escape from Berkeley alt fuels vehicle race: <a href="http://www.escapefromberkeley.com" target="_blank">www.escapefromberkeley.com</a><br> - ALL Power Labs on Twitter: <a href="http://twitter.com/allpowerlabs" target="_blank">http://twitter.com/allpowerlabs</a><br> - Shipyard Announce list: <a href="http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com" target="_blank">http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com</a><o:p></o:p></p></div></body></html>