On Mon, 4 Feb 2013 23:23:22 +1300, doug.williams wrote in message <36D416FEBC43433A9CFF313E88274ACA@dougspc>:
> Hi Tom, > > Pleased that you are still able to contribute to these debates, and > as you seek comment to your intentions to do some testing, here > goes(:-) > > Dear Doug and all: > > The Toplit Updraft gasifier produces a different gas (plus 20% > charcoal, mostly from the lignin) than the downdraft gasifier. I > believe it may be a cleaner gas, since cellulose (~ CH2O) vaporizes > to produce a different gas (CO + H2 + ?) than the lignin. > > My understanding of these open core concepts of gas making, is that > all the pyrolysis gases released at the descending flame front of the > raw fuel, are combusted in and with a portion of the char on the > upper gas outlet side of the flame front. Reduction would take place > in this narrow band of high temperature to give us the CO, but I > would expect to see the H2 start out low, and increase as the depth > of char increases.(Needs longer dwell time). ..quick question: H2 needs how much longer dwell time than CO? > Question. Have you done continuous gas analysis from start-up to shut > down? > > Your question mark in the equation suggests a combustible gas > (~CH20), which would have to survive the combustion /oxidation phase, > or does this vaporization take place as a portion of the char is > consumed first in oxidation,then reduction? Looking at these > gasifying stove rings burning as a blue gas, one might conclude that > there is little if any condensable tars present. If CH20 survives to > be measured as a gas, it's formation may be reflected in the H2 > variation if present, depending on exactly where the H2 forms. Having > said that, I have no experience to draw from, to know if there is > enough thermal inertia after reduction to allow "other" reactions to > take place. > > As soon as we get some warm weather, I'll try to measure the tar > content from each, using my 2 kW generator and a 5 gal tar filter > made from the charcoal. Comments, suggestions? > > As you expect to capture tars in charcoal, then I would want to have > good control over the gas cooling/filter temperatures, as the dew > points of the fuel moisture content are linked to carrying lighter > pyrolysis gas/oils through filter media. I'd want to know, especially > the downdraft gasifier, if it had a proven ability to make gas > without or known condensing hydrocarbons, using the fuels of the test. > > You also have the engine to feed you lots of info as to gas > condition, and I would use that as a pre-test before you add the > charcoal filter. A quick look under the throttle butterfly could save > you a lot of useless testing if you see the sticky stuff in there! > > I'm sure you know all these answers already Tom, but will watch for > your postings of the results. > > Regards, > Doug Williams, > Fluidyne---- > > -- ..med vennlig hilsen = with Kind Regards from Arnt Karlsen ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. _______________________________________________ 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/
