How to tune a foundry oil burner

[100model]

I'm not quite following - why would 3 hoses be needed for a mechanical pump?

A mechanical pump requires an inlet hose and outlet hose. A third hose is the most important because if for some reason the pump reaches too high a pressure a relief valve bleeds oil to the tank so the pump does not explode, stall etc. This hose needs to be connected on the outlet side of the pump to work.

 

[GreenTwin]

This is how I intend to plumb my pressure nozzle burner.

I think this will work.

The motor/pump connection will be a Lovejoy unit with rubber bushing.

The pressure nozzle will be installed at the end of the burner tube, in the same position as a siphon nozzle burner.
I will look for some details of the pressure nozzle and burner tube assembly.

 

[GreenTwin]

Here is some information on a Delavan pressure nozzle.

The Variflow configuration diagram is too complex for my use, and I will use my piping arrangement shown in the previous post.

I will be using a Type "B" solid 45 degree cone nozzle, rated at 2.5 gal/hr. (blue vial "B" as listed in the Delevan chart below).
Note that you can vary the output of most nozzles by varying either the fuel pressure or the compressed air pressure, over a range of perhaps 4:1 and still get good atomization.

 

[100model]

6. A motor and gearpump combination is a small, lightweight, portable package compared to many air compressors, and requires perhaps 2.0 amps at 120 volts. This is important for a remote demonstration pour, such as in the middle of a field where the only power is a small generator.

If I do a off grid demonstration where no power is available a propane tank can be connected instead of compressed air to pressurize waste oil. this propane can be recovered when firing the furnace in the next melt so no propane is wasted.

 

[GreenTwin]

Both the siphon nozzle and the pressure nozzle screw into a standard Delevan #17147 adapter.

 

[GreenTwin]

If I do a off grid demonstration where no power is available a propane tank can be connected instead of compressed air to pressurize waste oil. this propane can be recovered when firing the furnace in the next melt so no propane is wasted.

That is a clever idea.

.

 

[master53yoda]

Pat;
on your going to the pressure nozzle, bear in mind that the atomization compressed air is providing about 20% of the needed combustion air. you may find that the flame w ill be forming further into the furnace, the pressure nozzles come in different cone shapes I think you will find the solid cone nozzle will work best. Pressure nozzles designed to fire into a pressurized fire box which our furnaces are and the solid cone nozzle may give you a more solid flame. They also are normally firing into a larger low pressure firebox. you may find that you can't get complete combustion at the wanted 2.7 gal fuel flow with a pressure nozzle.
I have found that 15 lb air pressure gives me good combustion but my large furnace does not have the back pressure that a smaller crucible furnace would have.

I have enjoyed this thread

Art B

 

[oldCB]

It should also be noted that a correctly tuned oil burner will not produce any visible smoke.

This is my furnace running at iron temperatures.

Shaded welding glasses need to be worn when melting iron, since the infrared coming off the furnace and crucible will quickly sunburn your eyes.

I use an old refrigerator shelf as a shield, in addition to a face shield, when looking into the operating furnace.
Without the refrigerator shelf, your face shield will melt in a few seconds.
Without a face shield, you should not lean over the furnace to look into it, since the heat is extreme and intense coming out of the lid (like looking into a 2,800 F leaf blower).

An iron furnace will melt anything plastic that is near an open furnace, including clothing, shoes, camera, etc., sometimes up to 8 feet away.

You can actually see the fuel valve tree that I temporarily used in this video (above the keg top on the right side) (to determine optimum fuel flow for this furnace).

Dual compressed air pressure regulators, one for the fuel tank pressurization (10 psi), and one for the siphon nozzle for fuel atomization (about 30 psi).

The PVC valve above the leaf blower is for dumping the combustion air when starting the burner, so you don't blow the initial flame out.
Once the burner is running on compressed air and oil only, then you close the PLC combustion air valve fully, putting the total output (on the lowest speed) of the leaf blower into the furnace.

Edit:
A better lid lifter configuration is to move the pivot point down to about the center of the lid, eliminate the vertical chain, and use a bearing at the top of the suport tube, also about the center of the lid.
This lid lifter works well, but my new design is much more simple, and works even better (just a wrist joint that pivots and rotates), with the same U-shaped yoke seen below around half the lid.



View attachment 144424

Very cool!

 

[creast]

It should be clarified that 100model (luckygen/ironman) is using a drip-style burner, not a siphon burner, and has great success with it.
I tried to duplicate 100model's drip burner exactly, down to the last detail, and I could never get any sort of consistent control over it.

After many attempts to make my drip-style oil burner operate like 100model's, I gave up and decided I liked my siphon nozzle burner a lot, especially the very fine and instant control it gives.

If anyone else can get their drip style burner to work as well as 100models, then more power to you; you have figured out how to operate a very simple burner style. I can't make one work no matter what I try; perhaps it is just me.

With a drip-style burner, you literally just drip the fuel into the furnace, and let the combustion air carry the droplets over to the hot furnace interior wall, where it is vaporized.

One of the major dislikes I have about drip style burners is that you have to preheat the furnace interior to a red hot condition using propane, before you start your oil drip.
I don't use any propane to start or run my siphon burner (on diesel), and a gear-pump diesel burner (using diesel) also does not need propane to start or run.
So basically a drip-style burner forces you to have two fuel sources instead of just one, and that requires more fuel lines (one for oil, and one for propane).

There is really no free lunch in the foundry burner world.

The beauty of the gear pump pressure nozzle burner is that it does not require compressed air (atomization is achieved by the 100 psi fuel pressure expanding through the nozzle tip, just like a perfume atomizer/sprayer).
The pressure nozzle burner also does not require a pressurized fuel tank.
And a gear pump only requires a tiny amount of 120V power.

There is much to be said for the gear pump pressure nozzle burner, and I will be using it exclusively as soon as I complete my build.
The advantages of the pressure nozzle burner are:
1. No compressed air required.
2. No propane start if using diesel.
3. Instant 100% power at startup.
4. Very fine and instant burner control.
5. Very consistent and even burn, with no surging.
6. A motor and gearpump combination is a small, lightweight, portable package compared to many air compressors, and requires perhaps 2.0 amps at 120 volts. This is important for a remote demonstration pour, such as in the middle of a field where the only power is a small generator.


View attachment 144433


With a gear pump

.

Pat, I agree completely but we are using diesel not waste oil which I think 100model (what's his real name?) is using in his furnace.
I had contacted him some while back regarding his furnace and he said the fuel was pressurised. Now I guess he means pressurised by compressed air and not a pump.
When I used waste oil on the siphon burner I had to pre- heat it to achieve good spray from the siphon nozzle i.e lower the viscosity but I guess his method is squirting a strong jet of neat oil into the hot furnace.
This is early days for me on pumped diesel systems but I am already quite sold on it in some respects. It's quieter, controllable and no compressor foibles ( as in when using small workshop noisy types)
With my new setup I could take it anywhere and run off a 12v battery but then again for most stuff I could lug a propane cylinder

 

[creast]

In response to 100model regarding hoses. My setup just has one and that is to the nozzle itself.
The pump is mounted integral to the reservoir so the inlet is within the tank - no external hose.
The pressure regulation/relief valve is within the tank and vents back to reservoir- no external hose.
Speed control of the pump motor takes care of flow/pressure regulation which is pretty much fixed on pumped nozzles and the relief valve protects the system.
Rich

 

[GreenTwin]

I know his name, but I have never seen him post it online, and so I call him ironman, which is a screen name that he has used, and it fits him well.

I think he just drips the fuel into the combustion air stream, and his fuel line stops at the end of the burner tube, about at the inside face of the furnace.
I have seen some flatten the end of the fuel pipe, but generally I don't think that is done with a drip-style burner.

The main differnence between the drip burner and the spray burner seems to be fine control, and rate of response.
I could never get my drip-style to hold a setting very steady, but you can see in ironman's videos that his burner operates pretty consistently.

I feel like the added complexity of a siphon or pressure nozzle burner is well worth it, in order to gain the fine control and quick response.
When I can eliminate the propane and propane preheat, using a spray nozzle is a definite advantage for me.

Of course to each their own, and it is really about what works well for a given furnace and situation, and what you like.
Everyone has their favorite equipment and configurations.

.

 

[creast]

I know his name, but I have never seen him post it online, and so I call him ironman, which is a screen name that he has used, and it fits him well.

I think he just drips the fuel into the combustion air stream, and his fuel line stops at the end of the burner tube, about at the inside face of the furnace.
I have seen some flatten the end of the fuel pipe, but generally I don't think that is done with a drip-style burner.

The main differnence between the drip burner and the spray burner seems to be fine control, and rate of response.
I could never get my drip-style to hold a setting very steady, but you can see in ironman's videos that his burner operates pretty consistently.

I feel like the added complexity of a siphon or pressure nozzle burner is well worth it, in oder to gain the fine control and quick response.
When I can eliminate the propane and propane preheat, using a spray nozzle is a definite advantage for me.

Of course to each their own, and it is really about what works well for a given furnace and situation, and what you like.
Everyone has their favorite equipment and configurations.

.

Yeah ,
Much respect to ironman and olfoundryman too.
You can't knock them in either respect of their methods.
Rich

 

[GreenTwin]

Pat;
on your going to the pressure nozzle, bear in mind that the atomization compressed air is providing about 20% of the needed combustion air. you may find that the flame w ill be forming further into the furnace, the pressure nozzles come in different cone shapes I think you will find the solid cone nozzle will work best. Pressure nozzles designed to fire into a pressurized fire box which our furnaces are and the solid cone nozzle may give you a more solid flame. They also are normally firing into a larger low pressure firebox. you may find that you can't get complete combustion at the wanted 2.7 gal fuel flow with a pressure nozzle.
I have found that 15 lb air pressure gives me good combustion but my large furnace does not have the back pressure that a smaller crucible furnace would have.

I have enjoyed this thread

Art B

Hey Art B (the aluminum ingot guy).
Great to hear from you.

I guess one potential Plan "B" would be to use dual burners at 180 degrees, with 1/2 the flow to each, so about 1.3 gal/hr to each burner.

A dual burner arrangement would be more complex, so I will have to contemplate that.

I have tried a dual 180 degree siphon nozzle burner setup, and the flow is much smoother, with an even flame around the entire crucible.
Dual 180 burners use 1/2 the fuel, and 1/2 the combustion air, and so the air velocity is much less, and the flame does not climb the back of the furnace as it does with a singel burner at 2.6 gal/hr.

I will definitely try one pressure burner at 2.6 gal/hr first, since it may work ok.
My thoughts are if a drip burner with zero atomization will work, then probably a pressure nozzle will work too, but I don't know the dynamics of a pressure nozzle burner, so just talking off the top of my head.

For those who have seen it, Art's furnace uses two siphon nozzle burners, each with servo-controlled needle valves.
I think Art has a post on his scrapping furnace.
We should post a link here if someone can show me where that is.

Art is a fountain of knowledge for combustion/thermodynamics/furnace information, and I highly value any feedback he provides.

Pat J

 

[100model]

When I used waste oil on the siphon burner I had to pre- heat it to achieve good spray from the siphon nozzle i.e lower the viscosity but I guess his method is squirting a strong jet of neat oil into the hot furnace.

My furnace will not start on 100% waste motor oil so that is why I use propane for 1-2 minutes to warm up the furnace and then switch to waste motor oil. I don't use neat waste motor oil when melting iron, I use about 80% waste motor oil with 20% diesel so it burns easier in the furnace.

When I used waste oil on the siphon burner I had to pre- heat it to achieve good spray from the siphon nozzle i.e lower the viscosity

The other alternative to using diesel so the viscosity of the oil can be lowered is to heat up waste oil to do the same thing. Heating up large amounts of waste oil to temperature is more trouble than adding diesel for my set up..

The pump is mounted integral to the reservoir so the inlet is within the tank - no external hose.

If you use a gear pump then it needs a relief valve and it sounds like your pump is a centrifugal pump, is this correct? If so it does not need a relief valve.

 

[GreenTwin]

There is one video online of how to build a siphon nozzle foundry burner, and they show an oil line and a propane line, perhaps for the reasons that ironman mentions, that the burner is run on waste oil, and thus the burner will probably will not cold start on straight waste oil.

But I notice that everyone seems to build sipon nozzle burners with an oil line and a propane line, and then they start the burner on propane, even when they are using straight diesel.

If you are using straight diesel with a siphon nozzle burner, you don't need propane at all, since the burner will light on a cold start easily on diesel, even down to 32F, which is the coldest I have started my burner on diesel. I did not heat the diesel tank at 32F and the burner still lit easily.

.

 

[Toymaker]

When I was researching DIY burners for my forced air burner for boiler use, I came across a few YouTube posts that looked like they might work as foundry burners, so I'll post them here and see what the experts think I like the blue flame, indicating complete combustion.

Waste oil burner

 

[GreenTwin]

When I was researching DIY burners for my forced air burner for boiler use, I came across a few YouTube posts that looked like they might work as foundry burners, so I'll post them here and see what the experts think I like the blue flame, indicating complete combustion.

Waste oil burner

View attachment 144454

The problem I have seen with the youtube "burner" folks is that is seems they seldom actually use their burners in a backyard foundry/furnace application, and they don't seem to show the affects of long term burner usage.

I am definitely not a burner expert, but I can relay some experiences with my and other's use of what I call hot-pipe burners.
Any steel pipe that gets red hot will deteriorate quickly with repeated use as a foundry burner.
Even stainless steel will deteriorate fairly quickly.

So what I have heard about is that a red hot burner tube works for a while, and then the side blows out on it.

A red hot burner tube creates all sorts of other problems, since it will overheat the fuel line and possibly the combustion air line, not to mention waste energy.

You can also coke up the fuel line (and nozzle if you are using a pressure or siphon nozzle burner) if you overheat it.

A foundry burner tube (in my opinion) should be cool to the touch along most of its length when it is operating at iron melting temperatures.

A cool burner tube will last indefinitely.

Almost every burner design I have seen on youtube is what I would consider a very poor design for foundry use.
Most of these burners are for maximizing youtube views and comments, and generating impressively large but generally usless streams of flames.

Just my opinions/thoughts.
Opinions do vary on these topics.

Edit:

Another consideration with a foundry burner is you don't really want a really intense and concentrated flame, since you can damage the crucible.
You can also burn a hole in your refractory where the flames impinge on it if you have too intense and concentrated flame.
What you want is a gentle flame that swirls around the furnace wall without impinging on the crucible.

Any direct burner flame impingement on a crucible will cause it to quickly fail.

The blue flame color to me would seem to indicate an oxidizing flame, which generally is not used with a foundry furnace; at least not with iron melts.
Someone with more knowledge than myself can verify that blue=oxidizing (or not).

.

 

[GreenTwin]

This is a dual (at 180 degrees) siphon nozzle burner arrangement.
The photo is looking into the open furnace with both burners operating.

You can see that the flame is very evenly distributed low in the furnace, so that the heat can rise up and transmit heat to the furnace wall and crucible over as long a vertical distance as possible.

 

[GreenTwin]

This is a single sipon nozzle oil burner.

You can see the flame distribution inside the furnace is not nearly as even as the dual burner design, and the flame tends to climb up the back wall, since the combustion air velocity is twice that of the dual burner design.

The flame is basically only on one side of the furnace interior.

The single burner works well, and is far simpler than the dual burner design, but I think the dual burner design would reach iron pour temperatures more quickly than the single burner configuration.

The green arrow shows a cold spot in front of the burner tube, where the fuel and air are mixing, but have not yet started to combust.

Some folks tilt their single burner down slightly to reduce the wall climbing effect.
You can see that the flame on the back wall is already 1/2 way up the side of the furnace on its initial rotation.

The reason that a single burner works as well as it does is because once the furnace interior reaches its maximum temperature, it remains at a fairly consistent and evenly spread temperature.
The radiant heat from the furnace walls are what I think transmit most of the energy into the crucible.
If you open a hot iron furnace, you can find out very quickly just how strong the infrared energy is that is being radiated from the furnace wall.

 

[creast]

My furnace will not start on 100% waste motor oil so that is why I use propane for 1-2 minutes to warm up the furnace and then switch to waste motor oil. I don't use neat waste motor oil when melting iron, I use about 80% waste motor oil with 20% diesel so it burns easier in the furnace.

The other alternative to using diesel so the viscosity of the oil can be lowered is to heat up waste oil to do the same thing. Heating up large amounts of waste oil to temperature is more trouble than adding diesel for my set up..

If you use a gear pump then it needs a relief valve and it sounds like your pump is a centrifugal pump, is this correct? If so it does not need a relief valve.

I am using a gear pump and the relief valve is located in the reservoir itself. This valve is set to 120psi . Running pressure is 100 psi and achieved by adjusting pump speed to match the nozzle requirements.