Multiflow Burner Controls

I decided to build a multi-flow burner control for my siphon-nozzle burner, and this will be used in conjunction with my new low-mass furnace to experiment with iron melts.
The low mass furnace thread is located here: http://forums.thehomefoundry.org/index.php?threads/a-thin-hotface-beer-keg-furnace.26/

The idea was to come up with a simple method to allow a variety of flow rates to be selected quickly and accurately.
I really did not want to build a carburetor-type design, but rather something I could throw together quickly with parts that are relatively cheap online.

Since I have set up the low-mass furnace to work with three sizes of crucibles (#10, #16 and #20), I wanted to be able to select a fuel flow that matched the crucible size, although I am not sure that is necessary.

I have studied the data from other guys who have done a considerable amount of successful iron work, and compared the data, and have generally found that a low mass furnace equals quicker melts using less fuel, and the converse also seems to be true.

My guess is that I will generally use between 3 and 4 gal/hr for iron melts up to a #20 crucible.

I will most likely settle on using 4 flow selector valves, with associated needle valves calibrated at 1/2, 1, 2, and 3 gallons respectively, to give a range of between a low of 1/2 gal/hr and a maximum flow of 6.5 gal/hr.

Not rocket science stuff here, just a crude method, but I think it will work well.

For my combustion air valve (a 2" PVC ball valve), I will cut a piece of sheet metal in a pie-shape and scribe marks on it every few degrees, and then use a pointer on the valve handle, so I can record which combustion air flow setting goes with each valve setting.

There is a 3-way selector valve to choose from either diesel (starts on diesel) or waste oil (planning on running on waste oil), and also a master fuel cutoff valve.

The needle valves (not all are installed in the photo yet) will be flow-calibrated, and then the gland nut tightened so that they do not change settings easily. The needle valves will not be changed after the initial calibration.

I suppose this arrangement could work with other burner types, but for the guys who already know how to melt iron and which flow settings to use, this valve arrangement would not be needed.

The arrangement shown in the photo is a bit cramped, and I will omit one of the valves, and spread the others around on the manifold.

Each needle valve will have a 1/4" copper tube that extends down in an 180 degree turn to a second manifold below the first one, which will then feed out to the burner via an inline fuel filter.

 

Seems like a perfect way to overcomplicate things ...

Remember that fuel viscocity changes with temperature. It will be very hard to keep everything a constant temperature.
Needle valves are a pain with used oil, they clog very easily.

I would like to wish you all the luck with your setup, you will need it.

 

It does seem a bit complex, although I am planning on omitting one valve.

I use an inline automotive filter, and use clean diesel and will be using relatively clean used waste oil.
I have never clogged a needle valve when using an inline filter.

The viscosity thing may be an issue with waste oil, but I can always put a 5 gallon can of it in the shop the night before a melt and let it normalize (I can leave a little heat on in the shop since it is insulated).
With diesel, I have used it in hot and cold weather (perhaps 100F - 38F) and it is fluid enough that it does not seem to be affected by the temperatures, at least not where I can tell and difference.

Based on past uses of needle valves with oil burners, I am optimistic that it will work, and should give me instant flow rate selectivity at a wide variety of flow rates, but the proof is in the pudding, and I need hook it up and give it a try.

Not for everyone for sure, but I am pretty exited about what I may be able to do with it.
If it doesn't work, I will report back here the results.
I report successes and failures; its all part of the learning experience.


Edit:
Having discovered an Ursutz burner at a recent Steam Festival that works so well, I will probably try to duplicate that burner next, and I am sure I would not need a multi-flow arrangement for it.
The multi-flow control was for a siphon-n0zzle burner, for use with multiple crucible sizes.

If I can get an Ursutz burner to work correctly, my siphon nozzle burner is going to get kicked to the curb. I have plenty of uses for valves for other applications (air, water, etc).

 

And I thought it was fine control over the air to the syphon which determined the amount of fuel sucked? Or am I missing something?

In my design, its just a ball valve to the fuel.

 

My valve of choice would be a gate valve for viscous or slightly polluted oils.
Of course a small valve like 1/4" or even 1/8" depending on what size burner you plan to feed.

Or a bigger valve with a partly blocked gate. I have seen gate valves that open up to reveal triangles and wedges.

 

If you use only compressed air to control the fuel flow, then the output may vary with the level of fuel in the tank.

I have a tall tank, and the level can vary considerably, so I put 10 psi pressure on the fuel tank (with a 15 psi safety valve) to give a consistent fuel flow for any tank fuel level.
A pressurized fuel system also gives better control with a needle valve in my opinion, and would also work better with heavier oils such as waste oil.

And I have a remote fuel tank located in a storage shed, with perhaps 50 feet of fuel line, so the pressurized tank overcomes any flow problems due to fuel line length.

Bottom line is that if you can control your burner using compressed air pressure only, and it works well, then there is no need to change anything.

 

Sounds good PatJ, back to building and testing mine next week and all I can say is I hope it sucks

 

I've tried ball valves for mixture adjustment.. too finicky. life got good when someone gave me some high dollar 1/2" needle valves. see my video part 4.