Dear Dr Tom That was a great account of a good experiment. So my main point is that as the energy needed to remove the moisture is so much less than the 'missing char' why does the car disappear in (apparently direct) proportion to the moisture?
Thanks Crispin PS Prof Henrick Wallman also says there is no water gas shift reaction going on but I remain unconvinced (though willing to be) because I find way too much H2 in the exhaust. I have measured 15,000 ppm H2(EF). -----Original Message----- From: Tom Reed <[email protected]> Sender: "Stoves" <[email protected]> Date: Mon, 12 Nov 2012 11:40:24 To: Paul Anderson<[email protected]> Reply-To: Discussion of biomass cooking stoves <[email protected]> Cc: [email protected]<[email protected]>; [email protected]<[email protected]>; Hugh McLaughlin<[email protected]>; Bob Fairchild<[email protected]>; Discussion of biomass cooking stoves<[email protected]> Subject: Re: [Stoves] Thick wood and MC in micro-gasifiers was Re: Smoke-free biomass pellet fueled stove Dear Crispin, Paul and Aul: The water-gas reaction C + H2O ===> CO + H2 DH. 420. 280. 280. DH (delta H, but my I pad has no delta symbol), the heat produced by the reaction is -(560-420) =. -140 kJ/(12 g of C). In other words you would have to add 140 g of heat (plus enough heat to reach reaction temperature) to make the reaction go. <><><> My memory is that I dried wood chips in a 230 F oven for several hours, then prepared 7 bags of equal weight chips (100 g ?) and added enough water to each bag to bring total weight to 5,10,15, 20, 25, 30 % moisture, and then let the bags sit for a few days to equilibrate the water and chips. I then burned each sample until only charcoal remained (flame color changed fro yellow to blue) in our WoodGas battery blown stove. I was delighted to find 30,25,20,15,10,5 and 1% charcoal remaining. From this it seemed obvious that each lowest layer of charcoal, in order to ignite the subsequent layer of chips below it, had to be partially burned in order to remove the water from the next layer of wood chips in order to ignite it. Dry wood burns; wet wood won't. Since that experiment in my Denver lab, I have moved twice and would have difficulty finding my original notebook. But the experiments made so much sense, that I am sure the above description is in essence correct. Onward... Tom Reed Thomas B Reed 280 Hardwick Rd Barre, MA 01005 508 353 7841 On Nov 12, 2012, at 9:10 AM, Paul Anderson <[email protected]> wrote: > Dear Andrew, with copies to Tom and Morgan > > I am sending a copy of this reply to Tom Reed <[email protected]> . > This is the only email address he now uses, in case anyone else wants to note > it down. > > Tom did those experiments with known moisture a few years ago. Perhaps he > still has the notes. I think it was not prepared as a formal report. I > believe he said it was nearly linear, with about 0% char when MC reached 30%. > > 150mm diameter is beyond anything I have ever tried. I marvel when the 70 > mm branches pyrolyzed all the way through in the experiments done by my > Ugandan associates. There is a photo of the loaded fuel in the Quad TLUD in > the report of test results by CREEC on the Quad stove (see the report at > www.drtlud.com ). Thickness (diameter) increases the length of time of the > operation of the stove (quite logically). Jackson, the CREEC technician, > did a great job with having 3 different sizes of the same wood in the three > different runs. But we do not have funding for running repeated tests to > get sufficient replications. > > The issues include being too thick so that the pyrolysis gases are too slow / > too little to sustain a good flame at the upper combustion part of the TLUD. > > I hope that CSU can put that into their computer model. And I hope that CSU > will write something to the Stove Listserv or tell us where they are writing > something. So far they hold the biggest pot of funding for research about > micro-gasifiers, except for the big companies like Philips (and what BP did > in the past). > > Paul > > Paul S. Anderson, PhD aka "Dr TLUD" > Email: [email protected] Skype: paultlud Phone: +1-309-452-7072 > Website: www.drtlud.com > > On 11/12/2012 5:53 AM, [email protected] wrote: >> [Default] On Sun, 11 Nov 2012 20:01:02 -0600,Paul Anderson >> <[email protected]> wrote: >> >>> Crispin and all, >>> >>> I think that the char being created in a TLUD is not hot enough to >>> cause the water gas reaction. >> I take this view too, and even if it were hot enough the endothermy of >> the reaction would limit it. >> >> If this phenomena is important to us, e.g we want to maximise char >> retention, then it's worth knowing the optimum fuel moisture content. >> Also I had found there was a limit to the size of particle that could >> be thoroughly charred. I found I could not successfully scale up a >> tlud device to chare 150mm cross section longs which I hade carefully >> dried. What I never got round to trying, as I lost the farm workshop >> due to redevelopment, was seeing if such logs would char if embedded >> in smaller material. >> >> I no longer have a useful tlud device that will consistently produce >> measurable results but it may be worth doing some runs with oven dried >> wood chips which have been then re wetted with the correct amount of >> water to give samples of 0-25%mc wwb and weigh the char produced when >> lit with the same amount of liquid fuel. I would especially like to >> see the results when fed with primary air maintained at a constant >> flow. >> >> AJH >> >> _______________________________________________ >> Stoves 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/stoves_lists.bioenergylists.org >> >> for more Biomass Cooking Stoves, News and Information see our web site: >> http://www.bioenergylists.org/ >> > _______________________________________________ Stoves 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/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://www.bioenergylists.org/ _______________________________________________ Stoves 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/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://www.bioenergylists.org/
