[Clayart] Ele. reduction

John Hesselberth jjhesselberth at gmail.com
Tue Dec 22 19:20:13 EST 2015


Vince, I don’t know that I can be specific about the questions you raise, but I would add this.  It takes three things to start a fire or have an explosion: fuel, oxygen, and an ignition source. In one industrial process I am aware of they potentially have all three, but they operate it safely by thoroughly purging the vessel with nitrogen or other inert gas so there is no possibility of reaching an explosive concentration when they introduce the fuel and the ignition source. 

I guess my point is that you have to really know what you are doing when you work with systems were all 3 of the above may be present. Systems like the one I mentioned above are covered up with instrumentation and procedures so they don’t blow the manufacturing plant and the employees to kingdom come. And they have in fact operated without incident for many years. These are not systems to fool around with.

Regards,

John

> On Dec 22, 2015, at 11:29 AM, Vince Pitelka via Clayart <clayart at lists.clayartworld.com> wrote:
> 
> I've been thinking about this, and Sloss Furnace in Birmingham injects acetylene gas into their cupolas to melt cast iron, but that's a system with a lot of pressurized air flowing through to supercharge combustion of the coke and acetylene, so there's no chance of buildup of unburned hydrocarbons.  I guess the danger with an electric kiln is that it's basically a closed container.  Most of us who do a lot of reduction have seen the phenomenon where the damper gets closed too far and the kiln fills with unoxidized hydrocarbon gas, and then the damper is opened a bit and all that gas combusts with a whoosh!  I've never seen it do any damage to the kiln or wares, but that's a gas kiln with burner ports, flue, and spyholes to relieve the pressure.  In an electric kiln I am not sure what would happen once the combustion of introduced acetylene or LPG exhausted the available supply of oxygen and the uncombusted hydrocarbons started building up.  That's probably why it seems more sensible to use a Bunsen burner with an actual flame to introduce the reduction atmosphere, but it seems to me that the same thing could happen.  Perhaps someone on the list has had had experience introducing reduction with a Bunsen burner.  Wasn't there an article about this in CM, CT or PMI at one point?
> - Vince
> 
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpitelka at dtccom.net   
> http://iweb.tntech.edu/wpitelka/  
> 
> 
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