Hi Bruce and Toby, I an sitting here pecking away at other work, so can offer further comment:
Toby, I suppose your scenario is what would eventually happen. Although I would copy Doug Williams and run a serpentine exhaust arrangement of pipes with the wood laying on the pipes. My current fuel dryer has all the tubes flowing in parallel so the heat distribution is fairly even. Inlet temperature is 250C, outlet 50C. The hot engine air is blown through underneath and through the wood at 50C. Keeping the exhaust separated from the wood. I also use the exhaust directly into a 44 gallon drum dryer for wet wood, and you can dry it faster than you consume the wood for a small system, say upto 15 kWe in our experience. You can see between 400- 700C as an exit exhaust gas temperature. The point I gleaned from your comments was more about what happens when we condense the water out of the exhaust. There is a lot of sensible heat that could be used drive water out of wood especially here. We have a opportunity here to take advantage of the dry air this time of year to subliminate much of the water on the surface of the blocks. I digress. Water certainly can be seen forming on the upper blocks until the fuel mass heats through. We start with the lid on, then open it up to let the steam out, and stop when blue smoke begins to show out the top. This is I might add, using wood blocks for fuel. I found the best way to dry chips was an old tumble clothes dryer. I was more interested in the properties of the engine's exhaust. I suppose with air being almost 80% nitrogen, we could assume that engine exhaust's ability to hold water would be the same? I cannot answer that directly, but you always have a lot of water in engine exhaust gas, no matter what fuel, and will show you some in my next Fluidyne Archive Post. Hope this is of interest. Doug Williams, Fluidyne Gasification. _______________________________________________ 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
