some new boilers drive premixed fuel/air into the combustion chamber through a single blower. this premixing of the charge improves the combustion efficiency and cleanliness. i've found similar benefits of premixing fuel/air into the swirl burner on our gasifier.
however, things got more difficult recently when we started returning to blowers. with the ejector architecture, you have a very high velocity section that the flame cannot back up through. with a premixed blower, the gas/air velocity is much slower and it is much easier for the flame to back up into the blower. which brings me to my question: does anyone know how contemporary premixed boilers are keeping the flame out of blower? in principle, it seems you have three methods to chose from 1. keep the mixture outside the flammability limits of the fuel 2. keep the gas/air velocity faster than the flame front of the fuel 3. keep the temp below the autoignition pint of the fuel 1 is unattractive as it requires a multistage mixing solution. 2 we've made work, but it is fussy, and requires a rather consistent flow rater lest your "constriction" size get out of spec. also, when you are working with blowers for a gasifier, the main problem is to get to adequate pull vac, so canceling some of this by pushing through a constriction is not attractive. 3 we have not played with much. but it seems likely that a long honeycomb section might give adequate heat dissipation to quench a flame pass through. or maybe just a steel wool packed in the tube. we can of course go design this from scratch, but it likely has already been well explored and solved in premixed boiler applications. anyone know how they do it? any related prior art on flame arrestors that we might consider? j -- ------------------------------------------------------------------------------ Jim Mason Website: http://www.whatiamupto.com Current Projects: - Gasifier Experimenters Kit (the GEK): http://www.gekgasifier.com - Escape from Berkeley alt fuels vehicle race: www.escapefromberkeley.com - ALL Power Labs on Twitter: http://twitter.com/allpowerlabs - Shipyard Announce list: http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
