[Stoves] Burning wet wood

[Frank Shields]

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:frank at biocharlab.com> frank at biocharlab.com

www.controllabs.com











From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] 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$B-t(BO2 and $B-t(B
CO2 lines (they should depress in synch). The evaporation of all the
moisture early makes for problems later because then the wood it so dry it
won$B!G(Bt 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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