I never planned to create anything useful and AK-1, the first version of this burner, has successfully lived up to my expectations. Its very limited success intrigued me enough to build AK-2. As you will see, I did not expect much of it either. The burner is built crudely, using basic materials but it has been extremely effective. In fact it works so good that I'm adopting it to be my primary way to fire my furnace. The best things, that I have personally enjoyed coming from the past experiences with burning drip WO and coal, are that with this burner the furnace lights instantly, no smoke and gets hot extremely fast.

• The burner is fairly fault tolerant and does not require precision tools to build (I actually cut all the pieces by eye-balling the needed dimensions)
• The burner runs on WO mix with diesel (50/50) but it should function on plain oil or less diesel % ( I have not tried this yet, but I can use a more viscous fluid)
• The burner is powered by a regular blower, no pressured air or oil needed
• The burner has no nozzles to clog
• Despite the looks of the design the burner is easy to build. I have made the last one in about 20 min, having all the materials ready.

Theory of Operation

Turbine is span via passing air from the blower. Turbine’s blades atomize oil which is carried into the furnace. The turbine blades skim the surface of oil pool and spread the oil over the blades’ surface. Air passing through the blades picks up the oil off the trailing edge of the blades as well as the mist of oil created by rapid agitation.

The blades of the turbine are curved to scoop up the oil from the oil pool. This drives the oil to the center, while centrifugal force will try to throw the oil away from the center of the turbine. Oil spreads on the blades of the turbine into a very thin film. Consequently, the mist of atomized oil is blown by the air stream off the trailing edge of the blades. This is somewhat similar to the principle of the Babington burner, where oil is spread very thin over an increasing surface area, then the mist is created where high pressure air stream encounters the oil film.

I don’t think that this burner is as effective as Babington burner in creating very fine mist. The level of atomization is dependent on how fast the turbine is spinning so running the burner at full speed makes a more efficient operation. This burner is extremely simple to make, maintain and it does need oil pumps or sources of pressurized air.

Building the turbine

Tools and materials

I have built the turbine from copper flashing, commonly sold in home improvement stores. There are two kinds that are usually found: thin copper with tar and plain, thicker foil. The thicker foil is what I have used. Also, tin may be used, as long as you can solder it together.

• You will need tin snips a.k.a. aviation snips.
• You will need a soldering iron (45Watts or a small plumbing torch)
• You will need a coat hanger wire or similar.
• Small drill bit, with a diameter equal to the coat hanger wire.
• You will need ¼ copper tube that will supply oil

I started with cutting a slice of copper and rolling it into a tube, with a outer diameter such that it may be inserted into tuyere. Theoretically, you can use a solid piece of copper pipe, I just did not have the right diameter handy. When you roll the tube make it so the copper overlaps slightly. This will keep the oil, that will be thrown onto the walls, from running into tuyere walls. You do not need to seal the tube.
 

I made the end pieces of the copper pipe in two different ways. On one end, that is closer to the burner, I have left an extra piece of copper flap and then hammered it into shape. For the other end, I cut a piece of copper, made a hole in it for the oil supply tube, then soldered the piece to the copper "pipe". At this point you will end up with a copper tube that’s half closed on both sides, forming a small reservoir on the bottom.

Turbine is relatively easy to assemble. First you need a ½ inch of a thin copper tube that will closely fit over the coat hanger wire. It should be a loose fit. If you don’t have it, just roll a piece of copper into shape, this will be the center of your turbine. I have various, thin diameter tubes that I get from model and hobby stores for my various projects.Cut 12 rectangular pieces of copper that’s ¼ by ½ inch. You don’t need to make exact measurements. These blades when soldered onto the tube would be slightly larger than the copper pipe. That’s fine because you will need to bend the blades later.

            Tip. Soldering 12 small blades onto the turbines axle is tricky. The easy way to do it is to flux, heat each piece and touch future connection points with a bit of solder. Then to join all the pieces together you just need to briefly heat up the assembly so that the solder joins into one piece. I have used a quick jig to solder the turbine together. It’s a flat piece of scrap wood with a hole in the center (where the copper axle goes) There are 12 grooves where you can put the blade pieces. Once you put all the pieces together, heat the top of the axle until solder liquefies and joins all the pieces together.

The next step in making the turbine is to bend the blades. First you need to bend the blades like the blades of a fan. This will cause the turbine to spin when air passes through it. Slide the turbine on the wire and blow on it. Note which way it spins. Now you need to bend your blades as scoops, such that when the turbine spins the blades scoop the oil from the pool. Also at this time, check how the turbine fits inside the copper tube. The blades should not touch the walls , it does not need to be a tight fit. The turbine must spin freely when you blow on it.

Final assembly, note that one end of copper shroud is cut off to allow the turbine to be slid inside. However, when in-place, the turbine blades are always surrounded by the copper shroud. This is it. Blow into the tube and make sure that the turbine spins freely.

Operating procedures

Make sure that you have everything setup. I have a 11/4 inch pipe that I connect to the blower, then insert it into tuyere. Thus in my case, I insert the burner into this pipe before sliding it into the tuyere. Make sure of the orientation of the burner. The reservoir should be right up and not sideways, i.e. it's purpose is to maintain a pool of oil under the turnbine. It is very helpful if the tuyere is lightly inclined so that the excess of oil runs into the furnace, and not outside.

Test the burner with your blower without oil first. Note the minimum blower speed that you will need to spin your turbine and mark it. Usually a stronger flow will be required to overcome initial static friction before your turbine is spinning. If your turbine is not balanced well, you will need a stronger blast to run it.

I am making an assumption that your blower is controlled by some mechanism to increase/ reduce airflow. I am using a basic dimmer switch control, that’s available in home improvement centers. I am using 7.5 amp leaf blower that goes for about $25, brand new. It's noisy. At max, it should develop 150 m/h air stream. My blower is connected to 11/4 inch tuyere, so the maximum air flow is significantly less. I probably went to 80-75% of the blower speed at the most during my melts.

Load the furnace with scrap firewood. You may use charcoal if you like. The reason you need it is not to heat the furnace but to provide initial hot atmosphere to ignite the burner. In regard to the amount of firewood you need: you need to burn the firewood for a bit at the minimum air speed to run the turbine, before the burner lights. This is critical. If you have too little starter wood or charcoal, it will burn out quickly leaving your furnace bare and the flames will be blown off. Also, keep in mind that the more air is coming in, the more heat is leaving your furnace.

Sprinkle some lighter fluid to get the wood burning quickly. Check your setup and light the firewood. Slowly crack your blower to maintain vigorous combustion. Once the firewood is burning well, you can crank up the blower to start the turbine, then turn on the oil. Once you see the sputtering flames shooting from the burner, start turning up the blower slightly, don’t turn up oil just yet. You should see that furnace is running slightly rich. Whatever the charcoal you have inside, it will not burn as rapidly as it used to. You should be off and running.

Operation Tips/ Tricks/ Troubleshooting

• When furnace is running too rich (you may see a bit of smoke) the gut reaction, at least to me, was to turn up air supply. This results in higher turbine revs and even more oil being pumped in. The right response is to turn down oil supply first.
• If your burner sputters, that means that your oil spray is not even. Turn down oil, then turn up air and then slowly increase oil. Be patient, since it takes a bit of time for oil to go from control valve to the burner reservoir.
• Initially the burner is positioned well into the tuyere, so it's almost in the furnace inner chamber. Once the burner is lit, you may see that the steel axis wire is red hot. I thought that my burner will melt or at least the solder would melt, but this never happened. This was due to some oil evaporating and lots of cool air blowing through. I think that it's prudent to move the burner a bit out of the tuyere as furnaces temperature rises.
  

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