[Stoves] Thick wood and MC in micro-gasifiers was Re: Smoke-free biomass pellet fueled stove

Paul Anderson psanders at ilstu.edu
Mon Nov 12 08:10:37 CST 2012


Dear Andrew,        with copies to Tom and Morgan

I am sending a copy of this reply to Tom Reed <tombreed2010 at gmail.com> 
.  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:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com

On 11/12/2012 5:53 AM, ajheggie at gmail.com wrote:
> [Default] On Sun, 11 Nov 2012 20:01:02 -0600,Paul Anderson
> <psanders at ilstu.edu> 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
>
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