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burning inside burner tubes - update

updated wed 19 jan 05


Pfeiffer, Dan R (Dan) on tue 18 jan 05

After replacing the 4 straight pipes on my Olympic with 1" iron pipe nipple
with a coupler on the end and adding a washer with 4 holes in it I fired it
over the weekend and and got this result.

Overnight just pilot ring, temp 250 the next morning. I found it very hard
to keep the flame burning on top and still go slow up to 1100F. target rise
was 150/h, end result was about 300/h up to 500 and then slowed to ~150/h
from there up to 1100f. No soot! very quit! Flame spreads out a lot more
than with just the straight pipe. I found very small changes in the gas
valve make the temp go up quite fast. All went well going up ~300/h to
2000F, after this a let it slow up to about 1260C. I have a problem with one
burner that started to back burn and found the washer had got some soot in
the holes, removed it, while firing, and cleaned it and added 4 smaller
holes and replace it. In my next run I will add more holes to all the
washers. My guess is it got soot on it when I was playing around trying to
get the lowest gas setting without back burning and then as the gas was
turned up this caused a flame to come out the air intact from the
backpressure of the now too small pipe. As the temps got up to the very high
end the Oxyprobe showed some reduction bouncing around .05 -.02 and
sometimes as high as 1.0. Not sure but maybe the coupler slowed the gas and
this resulted in not as much secondary air as was need being pulled into the
kiln. One other thing that may have been a problem is I had flame deflectors
on two of the burners and this as it turned out is not needed but could have
helped slow the intact of air. I did not note any change in the copper
glaze's so there must not have been all that much reduction going on.

The end result was the bottom was two cones hotter then the top, but in
general not a bad firing. One big help would be to have valves on each
burner. I only need two at most running on the low end and that would have
make the turndown problem go away. Very hard to do as it is currently setup.
I am looking forward to hearing how the mr750's work for bill.

Dan & Laurel in Elkmont Al