Removing the O-Ring from a Delavan Siphon-Nozzle Oil Burner

Jeff-

That is a great video.
You are right, many people edit out the mistakes.

I started wearing leather boots after I burned my hand with an iron splatter, knowing that if it burned my hand, it would eventually get into my shoe also.

I also started using a hard hat that has the face shield attached, to give me head protection if the iron splatters up and then down on top of my head.

One really has to be proactive with the safety gear/procedures when melting an pouring metal.
You are correct, those burns can talk a long time to heal.

You are also right about running out on a weekend and trying to make molds and pour metal, and there being so little time to play around with things.
This has been a major obstacle to me consistently pouring iron, but luckily I have had a little time to focus on burner control and such and think I have a much better understanding now.

I told a buddy of mine about 1.5 years ago that I was giving up on the iron thing because it was taking too long to figure it all out.
He said "No you can't give up on iron now; you have come to far", and he is right, so I forge ahead, and I feel really good about yesterday's burner tests.

It is interesting to watch others adjust their burners.
Adjusting a burner is definitely an art (in my opinion).

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I'll be buying some "Welder's spats" to go over my leather boots.

 

That is a good idea.
Molten metal seems to go places you would not expect it to go.

I have seen others use a piece of leather on the back of the helmet, to prevent metal down the back of the shirt at the neck level.
The art-iron guys seem to have a lot of steam or whatever mold explosions, and they tend to wear the most gear.

 

Although I don't have any data I'm convinced that the size of our combustion chambers limits the amount of oil we can actually burn regardless of how much air we put in. It seems like an awfully small space to dump that much oil and by the time we elevate the air enough to get a "neutral" flame, we're apt to be cooling the furnace.
Thoughts?

Pete

 

I need to finish my new domed lid.
I may try to get out to the shop and work on that tonight.

 

Jeff-

There is some much interesting stuff in your videos that it is hard to go wrong with any of your topics.
Its great that someone puts so much time and effort into backyard casting stuff.

 

I see it as similar to car engines: using some form of supercharging -> denser fuel air mix -> increased rate of burn -> increased temperature -> increased flame propagation speed which lets oils burn fast.

 

I still have some unanswered questions about operating a siphon-nozzle burner and trying to melt iron, which are as follows:
I hope to be able to test and either prove or disprove some of these things.

1. Can a siphon nozzle burner be operated without compressed air, using only the 10 psi pressure on the fuel tank to achieve fuel flow, and thus let the burner act like a drip-style unit once the furnace is hot?
This would be useful if the furnace is taken to shows/displays where an air compressor is not available, or where only a small air compressor is available.
Edit: I tried this; it does not work and the fuel just puddles in the bottom of the furnace.

2. What effect does varying the compressed air pressure have on the furnace?
Some (scavenger) have said that using a higher compressed air pressure supercharges the mix, but I am not sure about that, and I suspect that too much compressed air can actually cool the furnace.
Edit: This seems to hold true during testing. Too much compressed air seems to make the burner run cooler.

3. What effect would varying the fuel flow rate from 3 gal/hr to 6 gal/hr have on melt times and fuel usage?
With aluminum melts, I was able to increase the fuel flow rate to over 6 gal/hr, and decrease the melt time to about 12 minutes from a cold start for 20 lbs of aluminum, so the overall fuel used was only a little over 1 gallon.
I would definitely like to shorten the time to pour temperature when melting iron.
Edit: Testing seems to shows that fuel flow rates above 3 gal/hr with my furnace (13" dia, 14" tall interior) actually cool the furnace from incomplete combustion.

4. What effect would using a combustion air preheater have on iron melt times and fuel efficiency?
I have seen numbers in the range of 30% increase in efficiency with a combustion air preheater, with shorter melt times.
Since I have removed the o-ring from the Delavan siphon-nozzle burner, I can now try using combustion air preheat, if I can figure out how to plumb it.
Edit: I tried a crude setup for preheating the combustion air before it goes into the furnace, but could not get very much preheat temperature.

 

At this stage my musings are largely theoretical, I'd been thinking of the combustion in terms of chemical reactions where temperature increases speed up the rate of reaction exponentially: every ten degree C increase roughly doubling the rate of reaction/combustion and assumed small pressure increases would have similar effects. I'll have to ask my expert Peter, as he'd mentioned a pressure figure in inches of water, might have been 3" of water from the blower without the furnace running, it wasn't much.

 

To burn a given amount of oil be it 3gal or 100gph, it requires a certain amount of oxygen to be consumed. Deviate from either one of these and the temperature will suffer. If you are talking flame temperature, I can get just as much heat out of a 1/2gph setup vs a 3gph setup. It comes down to the tuning of the air/fuel mixture. The only reason for a large volume of fuel is to overcome heat loss from the furnace construction. After you find that, anymore is just waste, not hotter. It's the same thing as the internal combustion engine. EVERYTHING in life runs on a bell curve in this is no exception. Take 1gph flow and force air at it until it gets the hottest it will get. Now add more fuel and watch it run cooler or take fuel away and it will go cooler. In the piston airplane world, we call this running lean of peak EGT to save a few bucks in fuel. People have discovered in the last 30years, it's cylinder head and egt temps is what destroys engines. So we find that peak EGT and rather than enrichening it cool her down, we actually keep on leaning to cool it down and run on the back side of the BELL CURVE. Power suffers slightly, but egt/cylinder head and fuel consumption drops like a rock. With the right monitoring equipment, it's a win/win situation.

Pat, if you can figure out how to run a siphon burner without a motive force, you will have solved the worlds problems. It's akin to perpetual motion. A siphon by definition is a tube or conduit bent into legs of unequal length, for use in drawing a liquid from one container into another on a lower level by placing the shorter leg into the container above and the longer leg into the one below, the liquid being forced up the shorter leg and into the longer one by the pressure of the atmosphere.

 

The motive force is 10 psi on the fuel tank.
Its not operating as a siphon, but rather the fuel is forced through the nozzle, similar to the way the pumped style nozzles operate, but without sufficient pressure to get atomization.
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Then I wouldn't really call that a siphon. To me that's more injection. 10psi on the fuel tank is no different than Richards 5gal pail he raises to roof level to push oil in his furnace.

 

And so that is why I am thinking it could perhaps be operated without a blower.
No sense wearing out an air compressor if you can turn it off after startup/warmup.

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My compressor runs for 20seconds once ever 5-7 minutes running a siphon burner. The only thing I see wearing out is the regulator switch. 10minute fix.

 

I tried turning down the compressed air to zero last night.
Does not work, the fuel just puddles, and lots of black smoke.
I had the furnace hot, but no dice.
The Delavan nozzle produces a pretty concentrated stream of fuel without compressed air (with a pressurized fuel tank), and the stream does not really break up or atomize, even when it hits a very hot furnace wall.

The best air setting for atomization seems to be about 30 psi.

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