Re: How about a ceramic kiln for burnout?


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Posted by bruce paul fink on January 02, 19100 at 17:37:05:

In Reply to: Re: How about a ceramic kiln for burnout? posted by John Griessen on December 31, 1999 at 11:45:49:

How do you make a stack afterburner? how much fuel and air do you use to avoid it going out, yet not be a waste of fuel?

Does it need baffles for good mixing?

Should it be a funnel over the existing kiln stack to collect upward flowing smoke without disturbing the gravity flow balance of the kiln flue?

Good questions John and you sound like you are on the right track.

It is also an area I seldom hear talked about and no longer

really think about.

I originally found the need for one when living in Northbrook Illinois and having a big burnout kiln in the garage (all concrete, including the roof) of a nice suburban area where they had never realized I was a sculptor with a foundry in their

backyards... (loved the town and people then and even could miss it if not loving it even better here).


That section of Chicago had natural gas for a fuel so it was easy to put a small but hot venturi torch into the area of the stack as it exited the kiln (a mid height downdraft system) and then just manually turn it on once the kiln was fired and any

wax gases might be flowing up. The flame was needed to keep the varying gas flow ignited. It then was turned off again during the final heat sink.

It simply finished burning them up using the natural venturi suction of the flame burner and an additional small venturi area around that burner to suck a little more air...

At times of a great wax drop out it was evidenced by a good hot red flame spewing from the top of the stack. (Usually timed for a 2 to 3 AM weekday display behind the pear tree, 20 feet away but between it and the main road ... risky but never had

the fire department show up).

Simple adjustments seemed to work as the gauge of it's success was to *nearly eliminate the smell from the top of the stack.

* I say NEARLY but don't get me wrong...

I could still smell or imagine what it should smell like, but the neighbors never could.

My University BFA is in Industrial Design so inventing and altering thoughts is a natural goal... still. And so today it is even simpler since I now use an oil burner firing into a ceramic lined area at the bottom of a kiln interior about 9 ft tall... the first 4 feet being below ground height and the most used mold holding area of the kiln in the upper section. The exhaust downdraft stack exit is low in the kiln and adjacent to the ceramic oil burner port so the 'after burner' in form is no longer needed... but actually is there as a flow part of the main firing burner. I do add a small paddle fan forced air addition to the stack at mid height to keep anything burning should it be

choking for air. These wax gases have to now drop down and leave the kiln interior by passing adjacent to this very hot and air enriched oil burner area... I call it killing two birds with one burner.

Does it work?

I guess so?

The gauge of it's effectiveness is based on the minimal non smell of the wax out of the top of the stack that is actually near 12 feet higher by the time it exits from the Studio Rhododendron bushes. (Another gauge since the gases are hot but not scorching the leaves yet).

Hope this helps. I would guess every kiln has it's own air flow, heat absorption and exhausting qualities but these were devised for this one here and is functioning really well.


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