You are right in a way, Peter. But the water has to leave the wood, yes? Where will it go if the surrounding atmosphere is saturated with water?
Let me illustrate with an extreme example: Try drying wood at, say, 110C in a pressure cooker, with the wood covered with water. If the exhaust gas has room for the vapor phase of water, the water will be carried away; if it does not (if it is already near its dewpoint), the gas will become supersaturated and nucleate condensation will occur. There will be rain in the forecast. I held my hand to the exhaust pipe of my 3.6-l automobile while it was idling. It was not scorchingly hot but it was palpably humid. Not exactly Science, I admit. Best, Mark -----Original Message----- From: Guag Meister [mailto:[email protected]] Sent: Saturday, December 18, 2010 4:48 PM To: 'doug.williams'; 'Discussion of biomass pyrolysis and gasification'; [email protected] Subject: Re: [Gasification] Drying fuel with IC exhause and other pleasures... Hi Mark ; This is true, but 100C is a special case because the water can exist as both a liquid and gas. If we discuss a slightly higher temperature, it may be clearer. If you heat wet wood to 105C by any means, all the water present in the wood will be a gas. Yes it will be in equilibrium, but since water as a gas occupies 100x more volume than water as a liquid, you will have succeeded in driving off 99% of the water. You could even do the heating with saturated steam and it would still work. Please correct me if there are any errors in the logic. Best Regards, Peter G. (armchair gasifierist) Thailand www.gac-seeds.com --- On Sat, 12/18/10, Mark Ludlow <[email protected]> wrote: > If the IC exhaust is saturated at > 100C, the best the wood can do is reach an > equilibrium moisture content with respect to this > environment. _______________________________________________ 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
