New way of atomizing oil for furnace?

[airmodel]

I found this video about using ultrasonics to atomize oil. So can it be adapted to atomize diesel in a melting furnace? Is this a good idea or is it trying reinvent the wheel?
<a href="https://www.youtube.com/watch?v=fUjyQvS60Xw" target="_blank">http://www.youtube.com/watch?v=fUjyQvS60Xw</a>

[AVTUR]

I don't think it would survive the heat. Not looking at all the video I guess it is made to atomise fragrant oils in the house

Ultrasonic atomisers have been around for a long time but for burning liquid fuels it is far easier to use a simple high pressure atomiser. One can be made very easily (using a bolt and a short piece of bar). All one has to do is swirl the fuel in a chamber and then force it through a little hole.

AVTUR

[Casting Iron]

I have seen several burner types, some very serious efforts to build a better burner, but often resulting in what are not very functional or effective burners.

One of the rocket design folks said something like "get rid of as many parts as you possibly can", and I think less is definitely more in many cases.

I tried building and using a drip-style oil burner, but could never get any sort of fine control on it, and never felt I had the burner really under control.
It seemed to have a mind of its own, and would suddenly do unexpected things, like surging, fluctuating, etc.
Obviously some have great success with drip-style burners, but that did not happen in my case.

I stepped up what I consider one level of complexity, and I use a siphon-nozzle oil burner which uses diesel.
It is basically a glorified paint sprayer, and it requires compressed air.
It is extremly controllable burner that will operate easily across a very wide range of fuel flows, and with a combustion air blower, or in naturally-aspirated form.
One guy I know build a micro-controlled dual siphon nozzle burner/reverb furnace, with servos and a thermocouple, and he maintains an exact temperature in his molten aluminum pool by modulating the two burners.  He said this can only be done because this burner style has very fine control capability.

Siphon nozzle burners have an o-ring, but I can up with a design that does not have an o-ring, and so that removes the component that can fail.
Siphon nozzles operating on diesel will light easily, and reach full power within seconds, even in cold weather, with no need for propane preheats.

One guy put in a huge amount of effort to try to build and perfect a rotating disk oil burner, and he used the disk to atomize the fuel.
Since there is so much heat near the furnace end of a burner tube, then termal expansion can be an issue.
As I recall, he was spinning the disk at a high rpm, and this seems like a good way to have major long-term maintenance issues.
Sort of a classic case of taking something simple that works well, and making something very complex, and something that did not work very well, and was not very reliable (those are my recollections of it).

The gear-pump-style pressure nozzle burner is basically a siphon nozzle with 100 psi oil forced through it, so the pressure atomizes the fuel, not compressed air.
I have one of these under construction, and have several fuel filters to keep the diesel very clean going into the pump, and also going to the pressure nozzle.
I have not completed this burner, but I intend to use it as my primary burner when I get it done.

I have seen a white paper on pulsing the fuel that is flowing to a siphon nozzle burner, and that supposedly increases efficiency by a significant amount.
From other white papers I have read, it is not a matter of getting the smallest droplet size possible, but getting droplets that are sized and shaped to give off the maximum amount of heat across the entire surface of the droplet.
Sometimes a more coarse droplet will burner hotter than a fine one.

Seems like an ultrasonic atomizer is basically an automobile fuel injector ?
Do they use the same technology ?

And similar to the way an ink jet cartridge works ?

Again, the heat around the furnace end of the nozzle may be a problem for an ultrasonic unit, especially if the burner stops suddenly, or if the combustion air flow is stopped.
The induction furnace coils are water cooled, so perhaps that could be used, but that is just adding more complexity where it is not needed.

Interesting idea for sure (ultrasonic oil burner for foundry use).

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[airmodel]

I don't think it would survive the heat

I did think of inserting the atomized oil further away from the furnace and let the forced air carry it into the furnace to be burned.

[Casting Iron]

I tried using the siphon nozzle with the tip of the nozzle back in the burner tube, but the result was spray that ended up on the tube wall, and dripped into the furnace, puddling in the bottom.

You can also potentially get combustion inside the burner tube, which will overheat it.
I had this problem with one of my naturally aspirated propane burners, when it was not adjusted right, it would backfire, and start a pulse-jet burning in the tube.

I think the ultrasonic idea has potential.
It just has to be figured out.

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[AVTUR]

I was a combustion engineer for the last thirty years of my working life and, believe me, combustion is difficult. A lot of time and patience (and money at work) is required before you get something that works. If it works don't change anything. Considering that both of you are probably retired why waste your time when you could be making model engines.

At work, but not within the office, combustion was referred to as the "Black Art". In an earlier company in the same business it was called "Black Magic" - usual black with very little magic.

I am sorry for trying to put a damper on things.

AVTUR

[fidlstyks]

I posted this Oil Burner in another thread. Although I find this an interesting concept, I have melted Aluminum, Brass and Iron since 1980, I like keeping it simple.
   An old man gave us a burner from an old oil furnace, which means diesel fuel. Many home foundries have used these.
   These used a gear drive for delivering fuel to the burner. I feel this is the most effective means.
    But I now use compressed air, as it runs off my compressor.  Fewer-less pieces to fix.
  The gear drive is surely superior. Gear pump drives  have a bypass valve. With air, it just stops flowing. I run a filter whether I use a pump or air.  And I just turn up the pressure when plugged up.
  There are a few basics I feel are most effective with any burner.
  The main concern is attomization.
  With a propane burner, it works very well to simply crimp down the end of the blow pipe.  When using only propane, I had a pipe with a coupler and screw in new tips as it flakes away. 
  I have had cast iron tips on the pipe, as cast does not flake away, steel does. Wear is from constant flaking, not melting away. Now I have a heavy steel slug welded With a smaller hole at the end on the blow pipe.  The reduction makes swirls and creates attomization, which is what were trying to achieve.
  I  do use dual fuels, 2 valves, gas or liquid is used. I  have a 1/8" steel pipe I crimped down at the outlet which creates a spray effect welded into my blow pipe centered about  2" from the  end of pipe-burner.
  What we are dealing with as a main concern, which is what the thread is about is basically mixing of fuel with air.
  A physicist might show a chemical diagram here of molecules of each atom of each element combined in a drawing. But basically what we need to think is, keep it simple, mixer.
  The blow pipe of the burner from the Oil Heater in attached picture has veins that create a swirl effect. This helps attomize fuel.
  With a restricted orfice in the fuel pipe , it makes a finer spray mist, which when meeting with the air becomes mixed more effectively.
  Flame height is an issue many fail to consider. When lighting any burner, one can see the fire sometimes gets hotter up above the actual orfice, where often no flame exists.
  The best most effective way to deal with proper ignition is to have 2 burners in a furnace.
  My furnace never gets hot where the burner enters. I call that the "dead zone" . So if you have two burners 180° apart, they ignite each other. Usually only in furnaces larger than for a no 10 crucible.
  I tried just having the burner farther back, so fuel ignites as it enters the furnace, but if it is not sealed in up at the burner, too much fire comes out .
   The fuel mixes, the difference in proper attomization is like taking a 30 mpg car and getting 32mpg. Who cares, were not pinching pennys here.

[Casting Iron]

Although my gear pump burner is not complete, I tend to agree, it will be the best way to run an oil burner, and is uses an fractional hp motor, and does not require me to run my air compressor.
I have on occasion transported my furnace to local shows, and luckily they had compressed air, but with a gear pump burner, I can take a small generator, and run the furnace basically anywhere.

I also agree that two burners at 180 degrees is the best and fastest melting arrangement.
I had one set up early on, but did not know how to adjust it, and so put it aside.
One day I will go back to a twin burner design.

There is definitely a dead zone in front of the end of the burner, and the combustion air velocity tends to make the flame climb up the back of the furnace at a 45 degree angle, which makes for some uneven heating.
When I was running dual burners at 180 degrees, the combunstion air velocity was 1/2 of what it would be with a single burner tube, and it eliminated the tendency of the flame to climb up the furnace wall.

I have seen some large foundry burners similar to the one you picture.
Part of the challenge with a home foundry is to scale the burner done from a large commercial unit to something that fits easily in a 2.5" diameter pipe.

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[Casting Iron]

Considering that both of you are probably retired why waste your time when you could be making model engines.

I am not retired, but I wish I was.

I cast my own engine parts, and really like doing that, since I can basically cast any engine that I have a few good photos of.
This is my first and only engine that I cast to date.
The flywheel was cast in gray iron, the rest I had to resort to casting in aluminum, since I did not have the iron casting thing worked out yet.
Entire design came from three photos.

My second engine will be a 1/2 scale 4hp Baker Ball Hopper Monitor, a 3D model of which can be seen in my avatar.

"Making model engines" covers a very broad spectrum, and I am on the far side of the spectrum.
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[Casting Iron]

This is my iron furnace operating with a single Delavan siphon nozzle burner, running on diesel at 2.7 gal/hr.
This furnace will take a #30 crucible, but I usually use either a #20 or #10, depending on what I want to pour.
A full #30 requires a crane, and pouring cart, which I have.
Easier to use a #20 or smaller though, and just hand lift it.

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