When I first set out to fire a kiln with hydrogen, I didn’t know how complicated or expensive it would be. I had to do quite a bit of research to come up with an idea for a burner design that I thought would work for me. One of the first good articles I came across on the internet was “The Hydrogen Homestead” which describes a project conducted by Roger E. Billings and a team of researchers. One of the things the project focused on is the conversion of natural gas burning appliances into hydrogen burning appliances. This information was quite relevant, as you can see, if you read it.
I think the most important idea here is that hydrogen has a very high laminar flame speed, and premixing the gasses is not required/recommended in the burner (no primary air needed). A burner design which mixes the gas and air at the burner tip is referred to as a “surface mix burner;” these are common in several applications. There is a variety of hydrogen related info. available at billingsenergy.com
Okay….. Below is a picture of the burner I made and the other necessary components I needed to conduct my hydrogen kiln experiments (minus the hydrogen). A special, standard hydrogen regulator (CGA 350) is required for connection to hydrogen cylinders. It is important to have a two-stage regulator in order to ensure a steady gas pressure for a kiln-like application. The regulator I have is made by National Regulator, and is often sold along with acrylic flame polishing equipment (another very interesting use for hydrogen). I was able to buy a cylinder of hydrogen from a local welding gas supply store. The cylinder contained approx. 197 cubic feet of gas, compressed to approx. 2500 psi and cost about $40.
In order to attach gas fittings (reverse threads or left hand) to regular fittings (NPT right hand). I had a custom hose made with fuel threads (reverse) on one end and oxygen on the other end. Then, going from my hose to the burner, I had to convert the fuel threads (NPTF) to standard pipe threads (NPT, or National Pipe Thread). For this problem, I was able to find a Regulator Outlet Bushing with the dimensions: 1/4″ NPT x B size Right Hand. Ooofta, that was a little confusing, but I’m sure there’s probably a simpler way to do that!
Below is a picture of the burner, with the blower removed. The blower is a 60 CFM Dayton 3030 blower. As luck would have it, I was able to screw the blower into the 2″ female pipe, even though the blower output is not threaded, it is very secure. As of now, I’m not completely sure how effective or necessary the blower is. I have done two firings (low-fire) in a little kiln (1 cubic foot) without the blower and they went just fine. Yes, I spent many long hours at the hardware and plumbing stores putting different parts together, everyone thought I was crazy….
Please remember, these are all parts that I cobbled together on a very limited budget. If I were able to spend a bit more, I would probably use all stainless steel and have some of the parts fabricated.
The burner tip, is probably the most important part for a burner like this. I made this burner tip from a 3/4 inch cast iron pipe cap. The challenge was creating the tiny orifices, which measure 25/1000″ which is .635 mm, or a #72 wire gauge drill bit. I was able to drill 26 orifices in it with my handy Dremel drill press, that isn’t a specific number, it’s just the amount of holes I was able to fit on the cap. The task was definitely not easy, as I broke several bits…. it worked, but I wouldn’t recommend it.
That’s it for today, thanks for reading.