Double, Down Draft Oil Barrel Kiln

[muddylove]

I am in the process of building a down draft barrel kiln similar to the one in the alternative kilns and firing Technique books by James Watkins and Paul Wandless.  I was thinking about trying to use two barrels with a shared chimney so that I could do two firings at once without the expense of having a second chimney.  I planned to use a t shaped pipe to join the two barrels with a central chimney.  Has anyone ever tried this?  I'm wondering if there would be enough airflow using one chimney to support the two barrels.  Any ideas?   

[muddylove]

I am in the process of building a down draft barrel kiln similar to the one in the alternative kilns and firing Technique books by James Watkins and Paul Wandless.  I was thinking about trying to use two barrels with a shared chimney so that I could do two firings at once without the expense of having a second chimney.  I planned to use a t shaped pipe to join the two barrels with a central chimney.  Has anyone ever tried this?  I'm wondering if there would be enough airflow using one chimney to support the two barrels.  Any ideas?   

[Biglou13]

Increase the volume of kiln.....increase the chimney exit volume and height. But is prolly not proportional. Also the t will increase back pressure and I doubt there are calculations for that.

 

What you are suggesting is like running two car motors to exhaust system of one.....

 

Changes will definitely have to be made. I've seen specific calculations for kiln to exit flue to chimney height But the T. Throws a wrench in.

 

Not familiar with plans. But I imagine forced air burn, may help here

[Biglou13]

Ditto

[muddylove]

That is what I was thinking.  I may just need to try it and fiddle a bit. 

[Biglou13]

Chimney....

 

I asked earlier but no answer.....

 

I'm sure fire brick $$$ is necessary as Chimmney material in kiln. Is there a formula where one can replace fire brick with regular brick and or a ceramic chimney flue?. There by reducing cost of chimney and use if high temp,bricks

 

Im building a wood (mixed) fire kiln, forced air. I'm sure if your firing a very hard reduction for extended period of time then that legnth changes. But if your only fring in mild reduction or less I imagine that measurement comes down....???

[Mart]

I do not have that books. Is it a gas kiln, you are building?

[muddylove]

I am planning on just sawdust/saggar firing/garbage firing in the barrel.  Basically, the pots just get tumble stacked on top of one another with combustables stuffed in and around the pots.  The pots are just lit on fire and then let to burn down.  I can fire just in the barrel as is but, I like the idea of adding the chimney/downdraft to increase airflow thus creating more even heat and a hotter firing.  I  I am using metal stove pipes as the chimney to the barrel.  It's not getting too hot so I don't need a brick chimney like a wood fire kiln.  I'd like to just sit two barrels side by side and have them share a chimney so that I do not have to buy more stove pipe.  I'll post some pictures of the kiln when I am finished.  At the moment I just have a barrel and a bunch of parts.   

 

Big Lou  I'm not sure what kind of brick is appropriate for a wood fired chimney other than fire brick.  I plan to build one of those eventually.  It can get pretty expensive to build using all fire brick.  It would be great to have a cheaper alternative.  My barrel kiln will cost a lot less than 100$ by the time I'm done.  It's not a big investment in money or time.  

[Mart]

it's only hot first meter or so  (1-1.5) and from there, you can use rainwater pipe or something similar.

[Phottery]

Corrugated metal drain pipe

[Biglou13]

Mart you saying. A meter to 1.5 meters of fire brick will suffice before the cheap stuff/less refractory stuff. And does this apply to a proper gas or wood fire kiln vs barrell kiln?

[Mart]

Mart you saying. A meter to 1.5 meters of fire brick will suffice before the cheap stuff/less refractory stuff. And does this apply to a proper gas or wood fire kiln vs barrell kiln?

 

barrel kilns are small so you can get away with this. With bigger wood fire kilns, no way!

 

Flames, that come out at the top of a down draft gas kiln are not that long (unless you are doing something really wrong, like dumping absurd amount of gas into your kiln) So, there is only a hood above the kiln for collecting gasses, that get directed outside.

 

Wood is something else. Wood fire produces really long flames and you actually need a draft too, so you need a tall chimney, made of refractory material.

[Stephen]

I am planning on just sawdust/saggar firing/garbage firing in the barrel.  Basically, the pots just get tumble stacked on top of one another with combustables stuffed in and around the pots.  The pots are just lit on fire and then let to burn down.  I can fire just in the barrel as is but, I like the idea of adding the chimney/downdraft to increase airflow thus creating more even heat and a hotter firing.  I  I am using metal stove pipes as the chimney to the barrel.  It's not getting too hot so I don't need a brick chimney like a wood fire kiln.  I'd like to just sit two barrels side by side and have them share a chimney so that I do not have to buy more stove pipe.  I'll post some pictures of the kiln when I am finished.  At the moment I just have a barrel and a bunch of parts. 

 

Big Lou  I'm not sure what kind of brick is appropriate for a wood fired chimney other than fire brick.  I plan to build one of those eventually.  It can get pretty expensive to build using all fire brick.  It would be great to have a cheaper alternative.  My barrel kiln will cost a lot less than 100$ by the time I'm done.  It's not a big investment in money or time.  

 

By adding that much draft aren't you going to burn out all the combustibles well before you have a successful firing of any type? I would think it's the continual addition of air and fuel that creates a hotter sustained firing. Is this your own design for experimentation or from a reference that has used it successfully?

[Stephen]

Oh one other thing you might consider is putting some wire mesh between layers of pots so as the fuel burns away the pots don't pile into each other and leave unwanted marks or damage.

[muddylove]

Stephen, once the barrel is lit and has burned down a little, you put a lid on top and crack it an inch or so.  That keeps the heat in and limits the oxygen so the fire doesn't burn too fast.  The idea is to get a nice smouldering fire. The wire mesh between pot layers sounds like a good idea.  I've never done that.  

[Biglou13]

mart mine is experimenta,   hard brick.   basically a rectangle box, cross draft, forced air, hard brick interior ifb outside.  ....... maybe go to pm or my kiln build thread

[Stephen]

Stephen, once the barrel is lit and has burned down a little, you put a lid on top and crack it an inch or so.  That keeps the heat in and limits the oxygen so the fire doesn't burn too fast.  The idea is to get a nice smouldering fire. The wire mesh between pot layers sounds like a good idea.  I've never done that.  

 

Don't mean to be a pain with the questions but I am getting ready to try a couple of small kiln alternatives to get a better understanding and hadn't considered a chimney for the pit firing kiln. I was going to do mine with basically a fire brick box with air intake at the bottom and the lid cracked only, loaded as you said with mesh in between layers of pots. I just thought that by adding a chimney it would create more draw from the intake and that would make the fixed fuel burn to quickly to get a successful firing. 

 

Have you fired yours yet with the chimney and what were the results?

[muddylove]

I haven't fired it yet.  I'm just finishing up building the kiln and then I still need to make pots to try it out.  I'm probably a month or so from a firing.  I'll post something when I get things going.  I've done regular barrel firing/pit firing before with mixed results.  I'm hoping the down draft on the barrel will make the results more consistent.