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Darren and Crispin,<br>
<br>
I agree with Crispin. <br>
<br>
Because you live in a developed society (UK), you can utilize the
advantages of low-cost, low-energy-consumption technology such as
fans and blowers and compressed air to accomplish your task more
easily. You are certainly not limited to the natural-draft
chimneys for your operation.<br>
<br>
I do not totally understand Crispin's description of the
<blockquote type="cite"><span style="line-height: initial;">Rocket
Mass Heater heat exchanger. This is a device with a hot central
rising pipe insulated from an exterior concentric pipe that
loses heat to the environment. </span></blockquote>
In theory it is fine. The only caution is that once you start
cooling the woodgas (TLUD pyrolytic gases), there can be
condensation and deposition of tarry stuff. What you have studied
about natural draft barrel-size TLUDs is based on "close-coupled
combustion" to burn those gases promptly. It all depends on what
you want to do with the gases, and you wrote that you wanted to heat
water.<br>
<br>
Heating water sounds simple, but I assure you that there is much to
be learned and implemented. Please keep us informed of your
progress.<br>
<br>
Paul<br>
<br>
<pre class="moz-signature" cols="72">Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: <a class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a>
Skype: paultlud Phone: +1-309-452-7072
Website: <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
<div class="moz-cite-prefix">On 5/5/2016 11:32 AM, Crispin
Pemberton-Pigott wrote:<br>
</div>
<blockquote
cite="mid:COL401-EAS446114F229C7F1F2CD1CA27B17C0@phx.gbl"
type="cite">
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">Dear Darren</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">A couple of suggestions you can
try with ease. In your favour is the scale. Some things work
better when the device is large. </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">Secondary air can be introduced
into the gas either above the fuel bed and burned elsewhere,
or the gas can be piped to a nozzle where air is entrained as
it blasts into a burner, perhaps no more than a length of 4"
pipe. </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">At ETHOS a few years ago the GEK
gasifier was demonstrated. In terms of scale it is not much
different from the barrel. The interesting thing was the
velocity of the discharge. It was powerful enough to power the
air entrainment. </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">What I am suggesting is that
there be no holes in the upper portion of the drum, that it
produce gas under at least the draft pressure generated
between the vertical column. That implies running the top at a
slight positive pressure which in turn means having a clamp-on
lid. </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">That implemented, you can use
the heat in the gas to your advantage. The next idea is to use
the device knows as a Rocket Mass Heater heat exchanger. This
is a device with a hot central rising pipe insulated from an
exterior concentric pipe that loses heat to the environment.
This cools the gas and as it does so, it gains density. This
increases the draft in the chimney above the reactor. The
increased pressure comes from, is powered by, the loss of
heat. </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">The net effect is that the
pressure from the closed system is increased beyond that
prevailing in the drum. This should allow you to burn the
cooled gas in an adjacent burner, not above the drum as you
envisaged. </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">Once you have a cooled gas
stream you can burn it as you wish. </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">Best regards</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;">Crispin </span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div style="width: 100%; font-size: initial; font-family: Calibri,
'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125);
text-align: initial; background-color: rgb(255, 255, 255);"><span
style="line-height: initial;"><br>
</span></div>
<div id="_originalContent" style="background-color: rgb(255, 255,
255);">
<div class="moz-cite-prefix">On 5/5/2016 7:37 AM, Darren wrote:<br>
</div>
<blockquote cite="mid:572B3EA0.4040100@vegburner.co.uk"
type="cite">Looking to work on a TLUD design based on a
standard oil drum (200-litre drum (known as a 55-gallon drum
in the United States and a 44-gallon drum in the United
Kingdom) to produce biochar from well dried wood. <br>
<br>
Ideally the stove would have a short chimney so as not to be
too high so that a pot/water tank/oven could be placed above
the stove to be directly heated by the flames. <br>
<br>
I've had a look about on the internet to see what people have
been building - almost all appear to have an extra 1/3rd of a
drum on top as an 'afterburner' chamber and a reasonably long
chimney on top of this. Making them rather tall for easily
positioning oven/watertank/pots for direct flame heating. <br>
<br>
None I have seen have an extra, large metal skin / tube
surrounding the barrel to provide secondary air pre heating
(as is done with some smaller TLUD designs). I wonder if
adding this could reduce the total working height of the
stove. <br>
<br>
Looking to make something that is nice and clean burning. <br>
<br>
Current ideas include - <br>
<br>
* positioning the chimney/riser at one side of the barrel to
allow heating on the rest of the metal surface next to the
riser - although I suspect a large diameter chimney is
required, leaving a hot surface of limited size. <br>
<br>
* charging the barrel 2/3rds full with fuel leaving the top
1/3rd empty as an 'afterburner' - having secondary air holes
positioned to jet in air at this height. <br>
<br>
Interested in any thoughts people have or any efforts people
know of oil drum TLUD designs where people are trying to
reduce the height, use the heat, or provide heated secondary
air. <br>
<br>
Best <br>
<br>
Darren <br>
<br>
see our previous biochar stove at <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://www.appropedia.org/Forest_biochar_rocket_stove">http://www.appropedia.org/Forest_biochar_rocket_stove</a>
<br>
<br>
. <br>
<br>
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