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Has anyone used a furnace IFC unit to control a gas kiln?


jrgpots
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I'm in the process of ordering 2 baso valves,  one main shut off valve, and two burner shut off valves. If I were to buy selanoid  valves on the main and baso valves, could I use a furnace IFC control board or oil burner control board to manage everything, including a high limit shut off?  I have a digital thermcoupler control. I could use that as my high limit shut off.  maybe...kind of like the Geil controller...

Jed

Edited by jrgpots
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8 hours ago, jrgpots said:

If I were to buy selanoid  valves on the main and baso valves,

It seems you are trying for on off  (cycling) control which would be hard to manage temperature rise. Proportional control is achieved in industry using  a temperature controller which is a PID loop device. PID stands for proportional, integral and derivative which is a way of adjusting by percentage while detecting if the rate of heating is increasing. Anyway all this tech stuff, these controllers today are dirt cheap, like 20-30 bucks so probably much cheaper than  a furnace control and much more suitable to operate in the temperature range of a kiln.

The PID control works great but for gas you really  need a valve that you adjust proportionally, say from 2% open all the way to 100%. So in addition to the baso valves which provide pilot safety you in theory need one of these controllers to proportionally adjust how much gas. In addition, for safety, redundant gas valves are usually used and a manual reset high limit is inserted. 

Thinking about this, if on/off control is used then some form of auto pilot Or pilot restart and maybe prepurge  is needed as well. The kiln could be restarted without pilot after about 1600 degrees but I believe the old Geil left the pilot bar on through the end of firing for safety  and had a toggle for soak at one particular temp or it could be toggled to limit. In soak it would cycle on at off at setpoint within a predefined differential and limit would drop everything out and require a full manual restart.

while this could be done, it’s probably too difficult to address all the safety requirements unless you are very familiar with the control equipment sequence of operation, fail safe designs and general safety for natural gas. My short answer is this is likely not doable for most.

Edited by Bill Kielb
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Unless you've got auto-ignition on the kiln, a control board would be overkill, especially if you're already using a high limit shutoff controller. With a basic Baso system, you'll be manually lighting the system, and the high limit controller will open or close the solenoids as needed to shut the system down when it reaches the safety temp. That's a pretty safe system. If you're using power burners, then you also want to wire it up so the solenoids shut down the gas if there's a power loss to the blowers- basically put everything on the same circuit.

If you're wanting the board to control the rate of climb, etc, then you need valves that can adjust the degree of gas flow, not just cycle them on and off like an electric kiln. When they cycle on and off, the pressure in the kiln gets messed up and the kiln fires very unevenly. In combination with the gas adjustments, you also need an automatic damper adjustment that can control the pressure in the kiln, as that will change as the gas and temperature increase. It becomes a pretty complex and expensive system to go fully automated.

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On 8/3/2020 at 9:04 AM, neilestrick said:

 When they cycle on and off, the pressure in the kiln gets messed up and the kiln fires very unevenly. In combination with the gas adjustments, you also need an automatic damper adjustment that can control the pressure in the kiln, as that will change as the gas and temperature increase. 

How does one monitor the pressure in the kiln?  Does a person use a manometer and a water column, a piezoelectric plate, or is there a special guage that costs a bundle of money?

Jed

Edited by jrgpots
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5 minutes ago, jrgpots said:

How does one monitor the pressure in the kiln?  Does a person use a manometer and a water column, a piezoelectric plate, or is there a special guage that costs a bundle of money?

Jed

I have no idea. I've only ever fired gas kilns manually. Automation takes the fun out of it!

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1 hour ago, jrgpots said:

How does one monitor the pressure in the kiln?  Does a person use a manometer and a water column, a piezoelectric plate, or is there a special guage that costs a bundle of money?

Yes, we use instruments that read pressure often compensated for temperature. Accuracy is a thing and do we trust one reading as representative of the average or do we need more than one point. Any way you look at it, it becomes difficult to be accurate and yes the more accurate the more expense. Should we check for flame roll out as well?  There are tasks that are relatively easy for humans to control precisely by observing secondary air ports etc... that are really tough to automate accurately. Learning how to fire a gas kiln by repetition and observation is truly a skill.

And yes electronic pressure sensors can use any methodology that is accurate and repeatable. Piezo May have a use here. Strain gauge and know diaphragm distortion likely have a place here as well as other methods.

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Just learn to see what the backpresure at thge spy plugs looks like. You may want to do this at night as its way easier to see. Once you learn what to look for (blue or yellow flame ) on a spy plug it will become second nature. Not that hard. The only guage thats made it super easy is an oxygen meter. This tells you the atmosphere in a number form. I fired for 25 years without one-seat of the pants I call it -its pretty easy. The oxy meter means my wife can check it and dial it in .

You do not need one-just another tool 

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