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<div>Ron, Paul,<br>
Below; Paul refers to 'equivalency ratio'. This would be the
amount of primary (under fuel air) divided by the theoretical
amount of air (stoichiometric) for complete combustion of that
fuel. Then he speaks of CO2, CO and H2 production and syngas
quality and variable fuel moisture contents. It would be nice
to see data that would correlate to his instance #2. I have
yet to see "Syn" gas composition measurements from a TLUD.
"process temperature might be below 500C" Where does this
number come from?<br>
<br>
"A lot of CO is emitted by the stove" <br>
Here he refers to CO that fails to be combusted in the burner
portion of a stove making it sound like it is a consequence of
conditions that occur in the fuel bed. "Syn"gas quality does
affect burner performance but burner parameters also affect
stack CO emissions.<br>
<br>
Instance #3 seems plausible.<br>
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Alex<br>
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Paul writes;<br>
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Ron,<br>
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One should look at a stove according to what it is designed to
use as fuel. Let us look, for example, at stoves that process
rice hulls. <br>
<br>
In a first instance, the stove might simply burn rice hulls.
Here we are talking about direct combustion where an air
equivalency ratio situates close to 1. Such a stove will produce
a lot of CO2 and H2O as well as relatively high levels of CO.
The fuel for such a stove is rice hulls.<br>
<br>
In a second instance, the air equivalency ratio might be 0.6,
the process temperature might be below 500 C, the moisture of
the biomass might be 20% or more, and too much secondary air
might be applied to the combustion of a dirty syngas containing
a lot of CO2 and H2O. Since the production of CO and H2 is
suboptimal, it might make sense in this instance to burn the
char in order to maximize the production of energy. But
unfortunately burning the char has serious problems: a lot of CO
is emitted by the stove, and heat is generated far below the
pot. If the char is burned within this second stove, the fuel
for such a stove is rice hulls.<br>
<br>
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In a third instance, the air equivalency ratio situates close to
0.3, the process temperature rises above 800 C, the moisture
content of the biomass situates at 10%, and the supply of
secondary air is kept low, but still adequate, to achieve total
combustion of the syngas. Here the production of CO and H2 is
optimized, the temperature of the syngas prior to combustion at
the burner reaches as high as 500 C, and not too much secondary
air is mixed in with the syngas. In this instance, up to 30% of
the weight of the rice hulls would still remain as biochar. But it
would make no sense to burn this biochar, since the production and
combustion of the syngas were optimized.<br>
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