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<div class="moz-cite-prefix">Ron,<br>
<br>
On 09/12/2012 8:33 PM, <a class="moz-txt-link-abbreviated" href="mailto:rongretlarson@comcast.net">rongretlarson@comcast.net</a> wrote:<br>
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<div style="font-family: Arial; font-size: 12pt; color: #000000">Alex
etal<br>
<br>
Thanks for the cite. I think I understand most of the plot -
which was of amazing duration!. I am especially amazed at how
uniform (and high) the flame temperature was in the late time
plot, even as the other plots were dropping.<br>
<br>
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It is a very steady gas producer. Conditions are constant except for
the distance and path composition between the pyrolysis front and
the burner. If it can be done over 100cm then why not 200 or 300.<br>
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a. Since you have this one from 2000, you probably have quite
a few more - from which I/we might extract a good bit more
information/ Any other similar plots around that you can post?<br>
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No I don't.<br>
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b. I am surprised that the "pyrolysis gas temperature"
was so much lower than the temperature of the char. Where was
the probe for this measurement - and had there been some mixing
of secondary air at this point?<br>
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No mixing of secondary air at that point. That occurs in and above
in a 5cm burner mixing pipe. The tmperature difference is largely
due to the nature of unshielded thermocouples in gas.For the most
part thermocouples radiate away heat according to the temperatures
of the surfaces that make up the sphere around them. A thermocouple
buried in the pellets that are all carbonizing at 700C will give a
fairly accurate measurement. A thermocouple in the gas above the top
of the pellet bed will radiate to the pellet bed and, in this case
the uninsulated container walls. The more that pellet bed shrinks
the larger the portion of the radiant sphere that is the cool
container walls. The larger the thermocouple, the greater the
radiant cooling , the lower the measurement. The higher the
temperature the greater the radiant loss, to the forth power. All
the gas is also radiating and convecting heat to the container
walls. So there are two reasons for a slow drop in gas temperature,
and one reason for not trusting either. The same holds true for the
absolute value of post combustion measurement. <br>
<br>
There are <span style="color: rgb(34, 34, 34); font-family: arial,
sans-serif; font-size: small; font-style: normal; font-variant:
normal; font-weight: normal; letter-spacing: normal; line-height:
16px; orphans: 2; text-align: left; text-indent: 0px;
text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-text-size-adjust: auto;
-webkit-text-stroke-width: 0px; background-color: rgb(255, 255,
255); display: inline !important; float: none;">gas-</span><em
style="font-style: normal; color: rgb(0, 0, 0); font-family:
arial,sans-serif; font-size: small; font-variant: normal;
letter-spacing: normal; line-height: 16px; orphans: 2; text-align:
left; text-indent: 0px; text-transform: none; white-space: normal;
widows: 2; word-spacing: 0px; background-color: rgb(255, 255,
255);">aspirated pyrometers which shield a thermocouple with
ceramic layers that approach gas temperatures and give better
numbers. We will soon be using an 10 footer to probe the chain
grate stoker gasses in carbonizer- pyrolysis-gasifier mode.<br>
<br>
Grate fun.<br>
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c. What is the present disposition of this equipment?<br>
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Its in the recoverable bone yard. I should have shown it to Crispin
when he was here.....or perhaps not:) <br>
<br>
Alex<br>
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Nice work<br>
<br>
Ron<br>
<br>
<br>
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