Toby, The exhaust is coming out of the engine at 400C. This will evaporate any moisture in the wood, drive off the volatiles and carry this mixture away with the hot nitrogen and CO2.
This is not like the tailpipe of an auto where the exhaust has cooled to the point where the water vapour condenses out. Suppose the exhaust is connected into the side of the bottom of a tall, verical cylinder containing a column of woodchips, - like a 6" diameter, double walled fluepipe, about 48" long. This column is placed just after the exhaust manifold where the exhaust is hottest, and preferably insulated to retain heat The chips at the bottom of the column will be heated first, begin to dry and torrefy and after a certain time period will have achieved minimum moisture, and achieved thermal equilibrium with the hot exhaust. Torrefied chips are hygrophobic and will not attract subsequent moisture. Once the woodchips have been in residence for sufficiently long for perhaps the first 6" to be fully torrefied, a vertical auger is started which pushes this first 6" layer through a sprung loaded flap and into the main gasifier reactor. The column of wood chips moves down and the next layer is kept in residence long enough for torrefaction. A thermal gradient will be set up in the column of chips, with the coolest and dampest at the top. Ken On 19 October 2010 14:05, Toby Seiler <[email protected]> wrote: > Ken, > > When the hot exhaust hits the wood in a direct heating set-up, the water > vapor will condense on the wood, making it more wet, not less. Yes it will > raise the temperature some but you will have combined the moisture and then > have saturated wood, not dry. It will be more problematic. > > With indirect heating you may get it done but it better be stainless. > There will still be condensation. Put your hand on your car exhaust and > feel the wet vapors. Do you see water dripping? That condensate will rust > out a heat exchanger in no time. > > Toby Seiler > > > > _______________________________________________ The Gasification list has moved to [email protected] - please update your email contacts to reflect the change. Please visit http://info.bioenergylists.org for more news on the list move. Thank you, Gasification Administrator
