The burner I am building is Reil style burner which will have enough output to fire a small aluminum melting foundry. I will not go into the physics behind the burner since this has already been done by Mr. Ron Reil himself. If you are interested in learning more then check out Mr. Reil’s site here.
The Reil burner is a very low budget design that allows anyone to piece one together using standard gas pipe fittings. In my case since I have access to a lathe, welder, and mill so I chose to build it with a few slight modifications. None of the changes that I did affects the original function or performance.
I chose to make a couple of changes to the original Reil design. The first one being that my burner is designed to have the jet size changed easily and quickly. The original burner design is simply and 1/8” brass nipple with a jet hole drilled into the side of it. I decided to make my own mini jets out of replaceable brass 1/8” pipe plugs. This way when it comes time to tune the burner I can easily experiment with different jet sizes. The second change I made was to how the flared nozzle is fabricated. Those people without a lathe have a greater challenge when trying the build an accurate flared nozzle. In my case I plan to machine the flare to precise tolerances.
So I started out with some basic gas and brass fittings. The rest of the parts will be used from metal I have laying around the shop. The combustion chamber and the nozzle are simply a ¾” – 1 ½” pipe adapter threaded to an eight inch section of ¾” gas pipe. The 1 ½” nipple used as the air intake duct was cross drilled to accept the 1/8” brass pipe fittings that will make up the gas jet assembly. I machined some collars, with set screws, and welded them to the sides of the intake pipe. The collars would allow me to align the gas nozzle on 2 planes and then lock it down into position.
Of course there are flow dynamics that enter into the equation. For example some of the unknowns are the amount air flow the intake will allow as well as the exact jet size that should be used. I am unsure if I will be running too lean or too rich. I can easily alter the jet size to accommodate however changing the air intake size would require a complete re-do. Anyways…I am basing my 1 ½” intake pipe calculation on other people’s experience. As far as the jet size goes Ron Reil recommends starting with a #60 jet. Since my #60 drill bit was previously broken I stepped it up one size to a #59. In order to be able to idle the burner down I opted to add on a choke assembly to the back of the intake. It is nothing more then a leftover 2” aluminum disc (one that I had prototyped for the tank clock) and a 6mm SS threaded rod. This way I can accurately control the intake air flow.
Onto the flared nozzle. The flared nozzle is said to work best with a 12:1 flare ratio over a length of 1.5”. Well it was Sunday afternoon that I was building this and I was using metal that I had. Since I had no heavy wall 1” ID cold rolled I drilled out solid stock to suit me needs. Drilling out the 1” center took awhile but came out beautiful in the end. Right on, all I have to do is flare it. Well this is where the measure once and screw it up permanently rule comes into play. I set my compound rest angle wrong and cut my flare too steep. Oh well, no fixing it now. I will use the wrong cut flare nozzle as a learning experience when it comes time to tune the burner. I will plan on cutting and new, and correct, nozzle. Hopefully during testing I will be able to see a difference.
So with all the machining and welding done I ended up with a completely serviceable propane burner. At least it looks like a burner, I suspect it can’t officially be called one until it actually shoots a flame. For now the burner sits on the bench while I collect the propane regulator, bottle, and hook ups in order that I can feed it some hydrocarbons. I will work to post a continuation on the performance of the burner which will make up the first part for my future foundry.