Ken, I once made a little experiment of torrifying granulated biomass with exhaust heat of a Lister indirectly . I found it working all right, the temperatures adequate, but the biggest issue are probably the tarry (condensable) fumes driven out. They would also be present in a direct exhaust system and have to be dealt with. I guess you don't want to vent them off. They are noxious and they mean money and energy. I led them into the Lister's intake and they burnt away nicely with the WVO diesel, but only for a short time. I guess on a longer base I would find the typical valve problems. I still want to persue this way - just no time.
See you in Zellingen next WE ? The GEK has seemingly arrived. Rolf Am Dienstag, 19. Oktober 2010 08:54:58 schrieb Ken Boak: > Andy, > > I'd also like to start a discussion about direct contact of the wood chips > with the exhaust gas. A pre-processing reactor that cooks the chips a > little batch at a time then dumps them into the main gasifier reactor, via > auger feed. As you say a "just in time" pipeline flow of pre-cooked, pre- > heated reactants. Water can be added if necessary as steam. > > Clearly the wood will become torrified, and the exhaust gas stream will > drive off and purge the wood fuel of moisture and volatiles, whilst raising > the temperature of the fuel considerably. There will also be an increase > in fuel energy density. > > If diesel exhaust was used (I'm thinking of a dual fuel Lister being > started up on diesel to raise process heat and provide mechanical and > electrical power for starting up gasifier), this will contain between 8% > and 17% unused oxygen, and around 80% nitrogen. Would the O2 be of > sufficient quantity to cause partial oxidation of the fuel and possibly > more heat? > > If the exhaust is from a woodgas engine - it will again be around 80% > nitrogen, plus CO2 and CO. If this relatively inert hot gas is used to > purge the woodfuel of all moisture and volatiles - is the resultant off-gas > ever going to have sufficient combustible constituents that it could be > ignited in any sort of air fed burner - or is the nitrogen loading just too > high? > > > Thoughts appreciated, > > > > Ken > > On 19 October 2010 02:13, andy schofield <[email protected]> wrote: > > Jim, > > > > Pushing calories around in the DTU graphic model, I find moving heat > > into the fuel is indeed the best use, for loose BTUs. > > In practice, heat transfer into wood is not easy because of limited > > conduction and radiation, and zero convection in a mound of fuel. > > The GEK method is like stir-frying vegetables in a wok; forcing > > convection. As each particle, contacts the walls of the pyrocoil; they > > cook. > > > > Someday I want to attempt direct contact of the wood with engine exhaust > > gas, after solving a certain sealing problem. > > A "just in time" inventory of heated wood; roasted to perfection. > > It is a shovel ready project. > > > > Looking forward to your findings. > > > > Andy > > > > > > > > > > > > > > > > > > _______________________________________________ > > 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.bioen > >ergylists.org > > > > for more Gasifiers, News and Information see our web site: > > http://gasifiers.bioenergylists.org/ _______________________________________________ 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/
