<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Arial; font-size: 12pt; color: #000000'>John (cc list):<br><br> What percentage of these industrial gas furnaces that you deal with use preheating of the combustion air? <br><br>And<br><br> Is this a totally different question than when working with biomass and pyrolysis? (or coal/coke in SA?)<br><br>Ron<br><br><hr id="zwchr"><b>From: </b>"John Davies" <jmdavies@telkomsa.net><br><b>To: </b>"Discussion of biomass cooking stoves" <stoves@lists.bioenergylists.org><br><b>Sent: </b>Sunday, July 31, 2011 11:22:03 PM<br><b>Subject: </b>[Stoves] Secondary combustion.<br><br>Dear Tom and all.<br><br>I work with industrial gas furnaces,<br><br>Some use a mixture of gasses with H2, CO, CO2, CH4 with traces of C2's to<br>C4'4's. - with a HV as low as 16 MJ/m3. Others burn Natural gas with a HV<br>of 40 MJ/m3. Some have preheated air and some do not.<br><br>All run with a minimum of excess air, with about 1.5 to 2% O2 in the flue<br>gas and very low CO.<br><br>The common factor in all these flames is the 3 T's . Turbulence,<br>temperature and time. All having turbulent mixing, A well insulated<br>combustion chamber, and a large area for the flame to burn to completion.<br><br>This is the scenario that we need to try and emulate as far as possible in<br>the secondary flame of our stoves. How close we can get to this is the big<br>question.<br><br>Regards,<br>John Davies<br><br>-----Original Message-----<br><br>From: stoves-bounces@lists.bioenergylists.org<br>[mailto:stoves-bounces@lists.bioenergylists.org] On Behalf Of Thomas Reed<br>Sent: 31 July 2011 01:38 PM<br>To: stoves@lists.bioenergylists.org; Paul Anderson; Hugh McLaughlin<br>Cc: stoves@lists.bioenergylists.org<br>Subject: Re: [Stoves] Stoves Digest, Vol 11, Issue 38<br><br>Crispin and All<br><br>Let's explore the plus and minus of preheating secondary air. <br><br><br><br><br>_______________________________________________<br>Stoves mailing list<br><br>to Send a Message to the list, use the email address<br>stoves@lists.bioenergylists.org<br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br>http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<br><br>for more Biomass Cooking Stoves, News and Information see our web site:<br>http://www.bioenergylists.org/<br><br></div></body></html>