Gas Kiln + 57 Gallon Tank Of Propane..?

[mousey]

Has anyone run a gas kiln off a 57 gallon tank of propane?  

 

On paper it seems doable.. a 280k BTU/hr kiln will draw about 12-14 gallons, allowing me a solid 4 firings per tank.

 

Are there any crazy gotchas here I'm missing beyond the obvious issues any gas kiln presents (learning curve, studio venting, so on)?

 

I have a little 1 cu/ft electric kiln and since I rent, I'm simply not ok with investing $3k to get the natural gas drop upgraded or $5k to get the electrical upgraded.  I'm actually committed to moving in 18 months specifically so I can start to build out my own studio but I need an option before that, and I feel a small propane tank could be a viable medium-term solution here.

[Jawpot]

There is a rate of evaporation that will take place by the propane in side the tank.  I once had a tank size / btu hour / temp chart but can not find it.

[High Bridge Pottery]

I'm confused, are you firing your electric kiln with gas or you have a gas kiln?

 

I have fired a 6 ft³ kiln on a 13kg (or was it 18kg, hmm) tank to cone10, couldn't find what that equates to in gallons. Had gas to spare but I think I could get two out of it if I am careful.

[Guest JBaymore]

You prime concern is not total BTU consumption for a firing... but the vaporization rate for a given tank GEOMETRY and installation nature.  (see links)  Unless you are using liquid withdrawal burners... which take that factor out of the equation. 

 

You are likely burning gas, not liquid... like almost all studio potters.  To burn it, you have to first evaporate it off the surface area of the liquid.  The vaporization rate is a function of the temperature of the liquid gas store... and the surface area exposed to evaporate from.  As you evaporate l;iquid to gas, that utilizes the latent heat energy stored in the liquid gas.... cooling it.  As the temperature of the liquid drops, for a given surface area, the amount of gas that can evaporate drops. 

 

Kilns use a high level of sustained draw.  So storage tanks typically are large to account for this.

 

http://www.propane101.com/propanevaporization.htm

 

http://www.amerigas.com/pdfs/Propane-Fast-Facts.pdf

 

That above should help.

 

best,

 

....................john

[mousey]

Ach.. thanks very much all, I knew I was grossly underestimating the issues at bar.   I'll review the links and see where this shakes out.

 

 

 

I'm confused, are you firing your electric kiln with gas or you have a gas kiln?

 

I have fired a 6 ft³ kiln on a 13kg (or was it 18kg, hmm) tank to cone10, couldn't find what that equates to in gallons. Had gas to spare but I think I could get two out of it if I am careful.

 

 

I have a very small (1 cu/ft) electric kiln now, I am looking at how reasonable upgrading to a larger, 10 cu/ft gas kiln on an smaller external tank would be, sorry if I didnt make that clear

 

So your stats are very interesting, and kind of back up what I thought I could expect from a 57 gallon tank, especially because I would be working primarily in the cone 4-6 range.

[Brian Reed]

I fire with Propane in a medium size downdraft.  My kiln is a 36cuft downdraft with 4 75,000 BTU venture burners.  I use two 250gallon tanks in tandem to fire and I have never had a problem.  Rather than measure everything I talked to my propane provider and the dual 250's were best because of local regulations about tanks over 250.  As it turns out I get about 5 firings before the tanks are at 30% when I call to get them refilled.  I found out the hard way that if I try and fire with less than 30% the vaporization cooling is too intense and freezes too quickly.

 

Prior to this I had a small 8.5cuft Torchbearer type kiln with 4 venture burners.  I used two 100lb tanks in tandem.  (I do not remember the gallons, but they were the tall skinny tanks).  The consumption of propane was fine with those however I would always freeze the tanks up on the last firing, I think it was the 4th.  Which I got into trouble a few times having to pour water over the tanks to warm them up.  I hated firing that kiln and so glad it is gone.