Dear Crispin, Tom and all,
I would think a batch mode would be better. A continuous mode means you have water vapor all the time. In batch mode one would heat and find the gas temperature goes to 100c. Then when the water is finally burned off the temperature rises and you can then push the fuel forward to do what you want to do with the now dry wood. Not sure this happens and have not seen a graph of this but think this is what would happen. Frank Thanks Frank Shields BioChar Division Control Laboratories, Inc. 42 Hangar Way Watsonville, CE 95076 (831) 724-5422 tel (81) 724-3188 fax <mailto:[email protected]> [email protected] www.controllabs.com From: Stoves [mailto:[email protected]] On Behalf Of Crispin Pemberton-Pigott Sent: Wednesday, June 12, 2013 9:05 AM To: 'Discussion of biomass cooking stoves' Subject: Re: [Stoves] Burning wet wood Dear Dale I believe it is easiest to burn wet wood in a continuous feed fashion. I have had some recent experience in Indonesia trying burn wet (pretty damp) wood in a TLUD. Some TLUD's heat pretty much all the wood at once (they vary). When that happens there is a huge burst of moisture in the emissions. This is visible on the HPT data quality check chart as depressed\xAD\xF4O2 and \xAD\xF4 CO2 lines (they should depress in synch). The evaporation of all the moisture early makes for problems later because then the wood it so dry it won’t stop self-pyrolysing. In other words if combustion conditions favour wet wood, later they do not favour dry wood remaining. Tom has some experience, as does UK-Andrew in burning pretty wet biomass. The essential point is to keep the primary combustion zone hot enough to run the fire and still evaporate all that moisture. Heat recycling is by far the easiest way to do that. Good to hear from you. Any recent experiments to repot? I have missed your great lab work. Regards Crispin +++++++ Have we ever looked at the question of how to design a stove to burn wood that is higher in moisture? It would seem that this is very important practical issue, and that a stove that could burn wet wood would be very popular. What makes a stove burn wet wood well or poorly? The only time I remember someone saying something about this was Crispin, who I believe said recently that preheating the primary air makes it possible to burn wetter wood. This would be easy with a batch stove, harder with continuous feed. Other than that, I can think of a couple things that might help burn wetter wood. Dale Andreatta
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