I interpreted this relative to some of my experiments with an "anila inspired" stove/retort that I made from a 20 pound propane bottle. A cylinder down the middle is where the fire takes place. Dry wood chunks/chips/biomass are loaded into the outer cylinder through a porthole, which is sealed and bolted down tight. Then the whole propane tank is wrapped in insulation, except for the top exit, and the bottom cone/grate sitting on a blower.The material in this outer area has no access to Oxygen as it is heated by the very hot walls of the inner steel cylinder (with 1/4" thick walls) fed air by a blower through 8 small 1/4 inch holes in a grate. As the wood in the outer insulated area is heated, the steam, gas, tars, etc, are directed into the "firebox" by 4 small 1/4" holes, adding gaseous fuel to the fire.. If I run the stove/retort (by adding blocks or chips at the top of the inner cylinder) for only a couple of hours, I get beautiful charcoal and torrefied wood. If I run it at full blast for perhaps 3 hours, the whole 4 gallons of biomass is turned to charcoal. (This is not the same as the charcoal made in my TLUD stoves.) Obviously, the temperature next to the glowing firebox is hotter than the temperature on the skin of the propane tank. I could take advantage of this destructive distillation of wood by not running the exiting products from the outer cylinder into the infernal in the internal burn area, but to an external collection tank, and then into the firebox. (I just haven't figured out what I would do with the liquids and tars.) There are various drawings of the grates used in the Anila stove, but my version (Anila inspired), with the blower, has only 8 holes. (Good advice from Crispin!) There isn't any smoke, but quite a bit of ash blowing up out of the firebox with the flame. (Nowhere for the ash to go but up!) I would imagine a solid hunk of wood would have a much different R-value that loose chips with air space between them. My porthole is just large enough to reach into with the hands, so I could insert larger chunks of biomass, but it would probably take much longer to convert them to charcoal.
On Thu, Dec 23, 2010 at 11:15 PM, Greg Manning <[email protected]> wrote: > > > Bruce, and List. > > FWIW, construction wood (houses) has a rough R value of 1.2 per inch (so a > 2 by 4 is about R 4.2 ( 3.5 X 1.2 )). > > This is considered "kiln dried wood", air dried would be somewhat less, > (say R 1) wet wood, way down, R 0.3. > > Your observed effect of the outer surface of a chuck of wood is exactly why > I only use wood chips for gasification, they do NOT have this effect, they > instantly go from wood to charcoal (in under 1 second), they stay intact if > the char state, and do NOT introduce tars and phenols farther down, in the > process. chips are IDEAL for gasifier use. > > Greg > > -----Original Message----- > From: [email protected] > [mailto:[email protected]]on Behalf Of Bruce > Jackson > Sent: Wednesday, December 22, 2010 7:58 AM > Where can I look to see the experimental results of heat transfer through > wood? > > I took to heart what folks said about destructive distillation. What I see > in > the stove, is that the wood isn't absorbing the heat as fast as the heat > from > the burning outer surface is making it. In other words the wood is both > destructively distilling, and drying. > It made me wonder what would be the optimal BTU input per pound (insulated > container of course) for wet wood. > > Also I wonder does the BTU input vary after the moisture content changes? > (this > from distilling ethanol, you need higher temps at the end of a batch run to > push > the EtOH out of the remaining water) I was thinking about the center of the > blocks being so well insulated by the remaining carbon that the water > couldn't > see the heat right away (or as fast as the water on the outer perimeter -- Ray Menke _______________________________________________ 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/
