Burnt Earth

Hi bc there I’m back. Weather has finally improved on the prairies and I’m back testing. I’m just running a test firing for a bisque. How fast is to fast for temperature rise?

Thanks for this. Easy to visualize in chart form. How much propane do you usually use on a 9 hour firing. I have a 250 gallon tank that I will be tying into. For now I’m just using 100# bottles. Should I be buying stocks in a propane company or is the usage not to bad.

With the steel I was just goi g to put in something similar to a wood stove but now my plans have changed and I will build a brick chimney once this kiln is placed in its permanent home. For now I will just use. 3/4” chunk of plate I have to cover the flue opening for testing. The kiln shelf will be an easy fit into the brick one when I build it. im really enjoying building this. It puts a big smile on my wife’s face and I get a kick out of making fire! thanks again everyone. I will keep you posted on my progress. Any more tips you can think of let me know. Cheers

Thanks. Do you guys just leave a gap in the chimney that you slide them in?

Thank you so much. This is exactly the information I was looking for in terms of firing this kiln. the 60 orifices were just what comes in the burners I used. I was planning on drilling these as need be once I actually had some run time on this kiln. I do have a Testo stack analyzer that I can see exactly what is happening with my combustion so I can tune this unit very precisely. Once my valve train is built I will be able to dial the burners any where between 4” WC up to 10 Psi. I am trying to make it as automated as possible with at least 3 different firing rates done through some different controllers I have. I will be installing a ProFire 2100 BMS with flame ionization detection as my safety shutoff and with this I get some different control options and communications so we can monitor remotely. The exhaust is currently 6x6” 3/8 thick square tubing. The kiln walls are approximately 6” thick soft finer fire brick and the exterior is lined with about 1/2” thick refractory blanket covered in a galvanized tin. So we will run oxidizing flame till around 1500f and then go to a reduction firing after that. That’s really good info. Do you know what PPM of CO you would expect to see at reduction. Probably would need to be under 250PPM to prevent sooting. What material are you guys using for dampers in a brick chimney and how are you installing them. Any pictures of that would be handy. For testing I was just going to slide a plate over the top of my exhaust. I am not the potter (that’s my wife) so any pottery terms kind of blow right over my head. I am just taking care of the fire end of things so any help is greatly appreciated. My background is natural draft tube fired heaters up to 20mm btu/h and forced draft boilers up to around 50mm btu/h in oilfield and industrial applications. I have worked on hearth and fore hearth burners in fibreglass production but never anything to do with pottery kilns. I do have a large assortment of tools at my disposal so I’m sure I can get this kiln dialled right in for her. once again thank you for all the help. It’s very much appreciated.

Ya I will deal with the chimney when I get it to its permanent home. I wasn’t sure how that steel would be but I’m sure it will survive long enough for testing. It is 3/8” thick so lots of metal to degrade. The burners are currently running #60 orifices and I will have up to 10psi available. I haven’t done the calculations yet but I can easily push these burners to 70,000 btu each. I have them installed in 3” stainless steel pipes through the bricks. the kiln will be living its life outside. I will be welding angle iron to the top and building a steel roof over it for snow and rain protection. the walls are about 6” thick. Double layered with soft fire brick. On the outside of the brick is a refractory blanket about 1/2” thick. That is covered with a galvanized tin. I had the kiln to around 1500f today and shot it with my thermal camera and it is running very cool outside temps. Under 30c after an hour running. I feel insulation is sufficient. I will be installing a baffle in the chimney but for now I will just cover the outlet. I had to cut the chimney short as my shop door is only 7’ tall but I have 4 more feet to put on for increased draft. Currently though the draft seemed sufficient. I haven’t analyzed the stack yet but the burners seem to be running very clean as I had no spot after an hour run time. How fast can you fire these gas kilns to temperature. Her electric kilns take a long time to get to temp? I can really hammer the fire at this thing and get it hot fast but I’m thinking that would crack cups and such.

Hello all, I am just in the process of taking an old electric kiln that was given to my wife and converting it to a propane fired down draft kiln. I have installed 4 burners in the bottom corners and made an exhaust from a 6x6 square tubing I had laying around. I have a few questions regarding firing. The kiln measures inside 30” deep, 24” wide and 36” tall with a curved roof. 1. Where is the best placement for a thermocouple and is it necessary for multiple thermocouples? 2. when doing a reduction fire where do you measure the excess O2? Are you using an 02 sensor in the chimney? 3. How fast do you usually fire one of these kilns? Are there temperature steps you try to achieve before increasing firing rate? Thank you for any advice. I am very familiar with combustion as I install and service large industrial heaters and boilers and am an instrument technician by trade but am very inexperienced in gas kilns. Currently my wife is using electric kilns but we want this one for our off grid property in central BC.