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<DIV>Stovers, </DIV>
<DIV> The following is a reply I sent on the wastewatts
list to someone, describing how I can forge small pieces of iron while heating
my greenhouse. In the previous letter I was describing the very high
temperatures I reached with natural draft. Something can be taken from this to
"warm up " some of your colder operating stove designs and make them more
efficient. I don't see the need for forcing the air with a blower if the proper
engineering is done to enhance the natural draft. </DIV>
<DIV> The stove mentioned is an old cross flow brick
lined coal/ wood stove made from 1/4 inch plate steel. The incoming air ports
are in the cast iron front door. I have had trouble describing this stove to
stove people in the past. Paul Anderson has seen the stove but not in operation.
Heat is scavenged from the afterburner. On a high burn during warm up phase, the
afterburner produces more heat than the stove itself. My plans are to put
preheat tubes in the stove to enable warm air jets to make the low burn settings
more efficient. As the stove is configured now, unless I burn most of the wood
down to charcoal, the stove is not so clean burning on low settings when I leave
the greenhouse overnight. </DIV>
<DIV> </DIV>
<DIV> <FONT style="BACKGROUND-COLOR: transparent"
color=#000000 size=2 face=Georgia><SPAN class=964551705-05082011>Hi Dan</SPAN>
<BLOCKQUOTE
style="BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px">
<DIV dir=ltr align=left><SPAN class=964551705-05082011></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=964551705-05082011>Depending on the alloy,
Iron starts burning around 1,800-1,900°F -- you will ruin your
work.</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=964551705-05082011></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=964551705-05082011>Reaching 2K°F or higher
is neither necessary nor a good thing for blacksmithing -- I use a propane
forge (1,600°F) for 95% of my work and fire up the coal forge only for
metallurgical reasons, never for temperature reasons.</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=964551705-05082011></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN
class=964551705-05082011>Dave</SPAN></DIV><BR></FONT></BLOCKQUOTE>
<DIV></DIV>
<DIV>Dave, </DIV>
<DIV> I usually hit the high notes while warming up the
burner on very windy zero degree F nights. Oak planks from skids or
equivalent kindling burn the hottest. Then as the stove burns down to coals I
use the char bed to heat my forging work. On a typical night the draft is not
enough to reach those very high temperatures. Adding length to the chimney would
enable better draft on less windy nights. Remember that this stove is heating a
greenhouse, so the primary purpose is to maximize the BTU output, not
temperature. Forging is just an added feature, recycling the heat. </DIV>
<DIV> Those temperatures are only on the surface of the
charcoal bed with some wood there and the door closed. The closed door enables
the primary air preheating to take place as the air coming through the ports in
the door passes over a hot brick. There is too much draft with the door open to
maintain that heat at the surface. Therefore unless my piece is small enough to
close the door, I bury it in the surface of the char bed which is a nice
stable bright red to orange heat. If I want an oxygenizing flame, I use the
surface of the charcoal and rotate the work but it is cooler.</DIV>
<DIV> One of the reasons I get such good natural draft I
believe, is because of the afterburner set up. As the flue gasses turn up into
the vertical 6" well casing secondary air is introduced, causing a swirl. As hot
secondary combustion takes place, the stove pipe expands from 6" to 8" diameter
five feet up. This expansion causes additional suction. By allowing additional
room at this key point, the expanding gasses do not have to create back pressure
on the draft. The combusting flue gasses accelerate vertically as in a turbojet
combustion chamber. That is what creates the signature howl in the tube. </DIV>
<DIV> There is a baffle inside the stove box that re
circulates the combustion gasses over the fuel bed until they are hot enough to
be sucked out the horizontal exhaust pipe. The thick steel exhaust pipe is in
the hottest part of the stove, acting like a gasifier throat. The partially
combusted gasses crack and reduce to lowest terms such as H. CH 4 and CO. These
hot ions are prime for rapid complete combustion when cold, dense secondary air
is introduced. </DIV>
<DIV> The funniest thing was I put a firebrick in the
front of the stove box to hold more ashes and charcoal from falling out.
The day I did that I burned the wrought iron retainer out by accident. That was
when I realized that I had created a open hearth like checker, which was
preheating the incoming air very efficiently. It's like putting a brick in the
toilet tank to save water. </DIV>
<DIV> Never know how you will find the next
breakthrough.</DIV>
<DIV> </DIV>
<DIV> Dan Dimiduk </DIV>
<DIV> </DIV></DIV></FONT></BODY></HTML>