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<p><font face="Liberation Sans">Hi Paul,Rolf and Colleagues,</font></p>
<p>This is to clarify Paul's questions. I hope the separations do
not confuse too much.<br>
</p>
<br>
<div class="moz-cite-prefix"> >Pyrolytic gas can be quite wet so
precise temperatures are risky to quote. </div>
<blockquote
cite="mid:ade70a21-d7a9-1513-3185-c427be457329@ilstu.edu"
type="cite"> Yes. There is no scrubbing or drying or other
preparation of the pyrolytic gas. In the TLUD world, the gases
are usually created in the 500 C to 650 C range. And the raw
biomass fuel might enter with as much as 15% to 20 % Moisture
Content (MC). <br>
<br>
If the MC of the raw fuel was lower (such as 5% MC), would that
help raise the temperature?<br>
</blockquote>
<br>
The short answer is yes, we don't need steam to displace gas volume.<br>
<br>
<blockquote
cite="mid:ade70a21-d7a9-1513-3185-c427be457329@ilstu.edu"
type="cite"> <br>
Hypothetical question: Part A. if the pyrolytic gases were
cooled to below 100 C, water could be removed by condensation, and
we would have lots of wood vinegar. However, there would also be
massive amounts of tars and "gunk" being deposited also.
However, the final, non-condensed gases just might have the
desired temperature when combusted. Those gases would be H2, CO,
methane-and-related-gases, and what else?<br>
</blockquote>
Cooling the gas is a waste of the heat that it contains. Any
condensed tars, hydrocarbons, or vinegars may have applications, but
also add to the technical difficulties for their collection. Their
removal, other than moisture best removed by drying the wood,
reduces the calorific energy of the pyrolysis gas. Difficult to
calculate, but also adding to the gas heating value will be carbon
particles. Normally we would seek to minimize these by using a
cyclone, but ceramics need reducing atmospheres, or read that as
carbon rich heated atmospheres, so carbon dust is great.<br>
<blockquote
cite="mid:ade70a21-d7a9-1513-3185-c427be457329@ilstu.edu"
type="cite"> <br>
Part B. Alternatively, after the removal of the wood vinegar,
perhaps the remaining gases plus the reheated tars, etc. could be
reheated to become a dry, quality gas for higher burning
temperatures. All of this would be with losses of thermal energy
during condensation and then the need to add thermal energy.
Could this have benefits that could justify the expense?<br>
</blockquote>
I think the previous answer covered this, but I see no benefit at
all to this suggestion. At a later date after there is a system
working, you will then have opportunity to extract condensates. Our
experience tells us that as toxic black liquor, the less you have
the healthier the working site. No exaggerating, it's a health and
safety hazard. <br>
<blockquote
cite="mid:ade70a21-d7a9-1513-3185-c427be457329@ilstu.edu"
type="cite">
<blockquote
cite="mid:90a737c8-10b1-1d29-bbde-9ec4fde79cfe@gmail.com"
type="cite">
<p>What I can tell you from experience, is that it always burns
hotter than clean producer gas, upwards of 1,050C, </p>
</blockquote>
If that is the maximum, will this be sufficient for Rolf and his
friend to use? There is no way to turn 1000 C into 1300 C,
correct?<br>
</blockquote>
Not well explained, sorry. Clean tar free gas will not burn over
1,050C, but if the system design produces pyrolysis gas which has
all it's hydrocarbons, then the temperatures will be upwards and
over 1,050C, a basic tar test for cleaner specification gas, <br>
<br>
<blockquote
cite="mid:ade70a21-d7a9-1513-3185-c427be457329@ilstu.edu"
type="cite"> <br>
But your next words I do not understand.<br>
<blockquote
cite="mid:90a737c8-10b1-1d29-bbde-9ec4fde79cfe@gmail.com"
type="cite">
<p>13-1500C is a rough rule of thumb for gas exiting the
combustion chamber. </p>
</blockquote>
</blockquote>
If you combust pyolysis gas full of hydrocarbons, then the flame
temperature will be 1,300-1,500C. One of the most difficult areas
of combustion is that thermo-couples start going crazy over 1,300C.
Expensive ceramic ones damage too easily, so once the TC melts, you
know the higher temperatures are present, possible over 1,500C.<br>
<br>
<br>
>I am not understanding what that means. The combustion chamber
is the "burner" of the pyrolytic gases?<br>
<br>
The short answer is yes if we were just creating heat. Ceramics like
Rolf is seeking to fire, are done in a tunnel kiln, and the tunnel
becomes the combustion chamber. The geometry is important to create
the combustion phenomena, but to design this we first need a tunnel
kiln to use.<br>
<br>
>>It has a very high radiation factor useful for refractory
application, but the price for this is that you will get a high ash
content in the kiln and flue dust emissions. <br>
<br>
>Something in the above sentence is not clear to me. The "kiln"
is part of the gasifier or is it where the materials are being
heated? And the pyrolytic gases of TLUDs do not >have ash in
them. And I am not understanding the source of any flue dust
emissions.<br>
<br>
The gasifier is close coupled to the kiln, and the burner is mounted
in this case, on the end of the tunnel kiln which forms it's own
combustion chamber containing the ceramics. The spent gas has to
exit the tunnel at some point, above the condensation temperature.
May be the ash from the carbon dust will settle in the tunnel
depending on combustion gas velocity. Usually, a correctly sized
flue stack is required to assist with removing the exhaust gas, and
this is where ash dust can become an emission. It would be good to
put aside TLUD understanding, as they work on a totally different
principle not relevant to this project need.<br>
<blockquote
cite="mid:ade70a21-d7a9-1513-3185-c427be457329@ilstu.edu"
type="cite"> <br>
Are your comments somehow referring to the FULL gasification
processes in downdraft gasifiers (pyrolysis AND char-gasification
are both occuring)?<br>
</blockquote>
No, Downdraft gasifiers more often than not make pyrolysis gas and
need char extraction to work. Full gasification as you say, need
minimum bed disturbance and between 1-4% of the fuel drops out as
char. Rolf only has a downdraft engine gasifier for his first
trials, and we should get plenty of pyrolysis gas out of that, at
least for the first tests to fire the ceramics. Maybe we will have
to extract char as well, but all that is still a long way off at
this point.<br>
<blockquote
cite="mid:ade70a21-d7a9-1513-3185-c427be457329@ilstu.edu"
type="cite">
<blockquote
cite="mid:90a737c8-10b1-1d29-bbde-9ec4fde79cfe@gmail.com"
type="cite">
<p> </p>
<p>The actual combustion is complex, but achievable in a non
regulated situation, emissions being the issue, both dust and
toxic gas CO,CH4, and Dioxins. Combustion of these gases have
been our focus for some 6-7 years, and current work at
CalForest in California, is to use this gas to dry the
incoming fuel to the charmaker.</p>
</blockquote>
The above sentences seem to indicate that your explanation is
about FULL gasification and not about only the pyrolysis process
with resultant charcoal creation.<br>
</blockquote>
We take raw producer gas from the Shasta gasifier, meaning hot
cycloned hydrocarbon free downdraft gas for the boiler green house
application. This has high carbon dust content which burns to ash.
This is a problem for the boiler, but just needs more cleaning
cycles than anticipated. <br>
<br>
The Charmaker is an updraft system and burns to waste the very dirty
pyrolysis gas. The gas flare vertically from high stacks making them
safer, as we have no space to work with them on the ground. The
radiant heat cooks you from about 3-4ft, so the chances are, unless
you have stood by an oil rig flare, many researchers just haven't
acquired this type of experience from pyrolysis gas flares.<br>
<br>
You might like to look again at the Fluidyne Archive last update
showing the charmaker and gas flares in action. The bigger flares at
higher output are not shown mainly due to us too busy keeping up
with the input fuel flow. Earlier updates show the Cyclomix
burners and combustion chamber hooked to a heat exchanger, so there
is plenty of info to brush up on as we developed these larger gas
making system components. When operational, we collect data from
those points important to both the gasifier and process, including
continuous gas analysis, which cannot be used for pyrolysis gas. (to
dirty) <br>
<a class="moz-txt-link-freetext"
href="http://www.fluidynenz.250x.com/">http://www.fluidynenz.250x.com/
</a><br>
<br>
Doug Williams.<br>
<br>
<br>
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