<html><head></head><body bgcolor="#FFFFFF" text="#000000" lang="en-US" style="background-color: rgb(255, 255, 255); line-height: initial;"> <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 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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</blockquote>
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