Oversized Stainless Keg Furnace Build

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PatJ
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Oversized Stainless Keg Furnace Build

Post by PatJ » Sat Jun 13, 2020 2:32 pm

I build an iron furnace back in 2012, and had a few successful iron pours with it.
Due to its high mass, it was slow to melt iron, and so a couple of years ago, I build a new oversized keg furnace, and it works much better at melting iron.

I am able to melt and pour gray iron with good consistency, and can make parts that are defect-free and easily machinable.

Here is the furnace in action:

https://www.youtube.com/watch?v=3YmsPjGsXgA

I often cast at night because it gets so hot in the summer here in the South-East.
It is also much easier to see what is happening with the furnace and burner at night, since the sunlight tends to wash out colors.

.

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BigDumbDinosaur
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Re: Oversized Stainless Keg Furnace Build

Post by BigDumbDinosaur » Sun Jun 14, 2020 8:32 pm

PatJ wrote:
Sat Jun 13, 2020 2:32 pm
I build an iron furnace back in 2012, and had a few successful iron pours with it.
Due to its high mass, it was slow to melt iron, and so a couple of years ago, I build a new oversized keg furnace, and it works much better at melting iron.

I am able to melt and pour gray iron with good consistency, and can make parts that are defect-free and easily machinable.

Here is the furnace in action:

https://www.youtube.com/watch?v=3YmsPjGsXgA

I often cast at night because it gets so hot in the summer here in the South-East.
It is also much easier to see what is happening with the furnace and burner at night, since the sunlight tends to wash out colors.

.
What are you using for fuel?
—————————————————————————————————
I'm an old guy. What's your excuse? ☻

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PatJ
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Re: Oversized Stainless Keg Furnace Build

Post by PatJ » Mon Jun 15, 2020 1:56 am

Diesel is the fuel.
.

jscarmozza
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Re: Oversized Stainless Keg Furnace Build

Post by jscarmozza » Tue Jun 16, 2020 11:44 am

Pat, it seems like you have a good handle on the process, you may want to think about trying different oil additives to your diesel fuel.
I thought about oil firing one of my locomotives, so I made a trial nozzle and experimented with it on compressed air and kerosene. I was near the end of the trial when I added about an ounce of non detergent motor oil to the remaining half cup of kerosene left in the fuel tank, what a difference in the flame! Without changing the air pressure the flame moved from about 2" away from the nozzle to within a half inch of it and the flame color went from light yellow to dark orange. The heat output was unbelievable, it melted a hole in the cookie sheet that I was doing the experiment on and turned the fire bricks that the flame was hitting white hot. This is easy to do and may give you more heat output.
Good luck, John

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liveaboard
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Re: Oversized Stainless Keg Furnace Build

Post by liveaboard » Tue Jun 16, 2020 6:11 pm

I also made burners for kerosene, but I had a particular situation.
I wanted high and controllable heat output for a long period, to fire heavy ceramic sculpture.
We were living in India, and although we had electricity, it was very unreliable. In fact, the only thing you could depend on for sure was power cuts.
Gas was precious and hard to get.

I built a downdraft kiln with an 8' chimney, that had good draw. Too good, I had to pinch off the flow with firebricks on top when it got hot.

There were 3 generations of burners, and the last ones worked really well. I used an LPG tank for the fuel, and pressurized it with a small compressor, or a 12v one if the power went out. Starting at 10psi, finishing at 100psi for full output.
I bought factory made pressure stove heads for preheat and ignition, they would burn just to vaporize the fuel for the main burner jets.

Later, I added a programmable controller than ran on an inverter + battery backup.
I can't remember the numbers, but these things cranked out a lot of energy. It could be heard at the other end of the village, sounded like a rocket engine. 30 liters of fuel was required for a full burn, ending at 1000 C, that's 1830 F

Long ago, I made a webpage with pictures if anyone cares; http://www.amsterdamhouseboats.nl/press ... burner.htm

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PatJ
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Re: Oversized Stainless Keg Furnace Build

Post by PatJ » Tue Jun 23, 2020 5:47 pm

jscarmozza wrote:
Tue Jun 16, 2020 11:44 am
Pat, it seems like you have a good handle on the process, you may want to think about trying different oil additives to your diesel fuel.
I thought about oil firing one of my locomotives, so I made a trial nozzle and experimented with it on compressed air and kerosene. I was near the end of the trial when I added about an ounce of non detergent motor oil to the remaining half cup of kerosene left in the fuel tank, what a difference in the flame! Without changing the air pressure the flame moved from about 2" away from the nozzle to within a half inch of it and the flame color went from light yellow to dark orange. The heat output was unbelievable, it melted a hole in the cookie sheet that I was doing the experiment on and turned the fire bricks that the flame was hitting white hot. This is easy to do and may give you more heat output.
Good luck, John
Thanks John.
It took a long time to figure out how to make consistent iron castings that are easily machinable, and I got input from several art-iron folks who do a lot of iron casting work, along with help from a few people online who also do a lot of successful iron work.

I experimented with many types of burners, and there are several types of burners that will melt iron well, including the siphon/pressure nozzle designs, the Ursutz, drip-style, and propane/LPG burners.
All these burners require two critical items, which are:
1. Sufficient combustion air added to the furnace via some type of blower.
2. The correct mixture of fuel and air to produce complete or near complete combustion of the fuel.

As far as fuel, I have not seen a difference between people using waste oil, kerosene, diesel, veggie oil, or propane/NG.
All of these fuels have similar flame temperatures.
Here is some data I found online:

Common Flame Temperatures

Acetylene with Air 4532 F
Acetelene with pure Oxygen 6296 F
Natural Gas with Air 3562 F
Propane with Air 3596 - 3623 F
Propane with pure Oxygen 4579 - 5110 F
Wood 3596 F
Kerosene 3810 F
Light Fuel Oil 3820 F
Medium Fuel Oil 3815 F
Heavy Fuel Oil 3817 F
Coal 3950 F approx.

Heat Value of Materials

#2 Diesel 138,500 BTU/gal
Kerosene 135,000 BTU/gal
Natural Gas 100,000 BTU/therm
Propane 92,5000 BTU/gal
Sawdust (green) 10,000,000 BTU/ton
Sawdust (dry) 18,000,000 BTU/ton
Electric 1.0 kWh = 3,412.14 Btu

Oil burners act entirely differently outside of a furnace than they do when operated with a furnace.
The trick to melting iron is to use the right fuel flow (about 3 gal/hr for diesel), and the right amount of combustion air (generally slight flames coming out the furnace lid opening).
Using more or less than 3 gal/hr of diesel seems to make the furnace run cooler, and that indicates that there is a sweet spot for how much fuel a given furnace size can completely combust.

I use diesel because it is clean, readily available at most gas stations, doesn't contain heavy metals, and it works consistently.
Most people use what is readily available, and what is easy to use.
Some folks who use waste oil end up using diesel due to all the problems you can have with waste oil, such as sludge, water contamination, and the mess of trying to store/handle/filter it.

Some of the change you notice between the different fuels may be because of viscosity.
Changing to a higher viscosity fuel will increase the fuel flow, so that will affect how hot it appears that the burner is running.
Kerosene seems to be thinner than diesel, and diesel is thinner than motor oil.

The furnace interior gets extremely hot when it comes up to maximum temperature, and so it will vaporize and combust almost any fuel you put in it, as long as your air/fuel mixture is correct.
.

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PatJ
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Re: Oversized Stainless Keg Furnace Build

Post by PatJ » Tue Jun 23, 2020 6:05 pm

liveaboard wrote:
Tue Jun 16, 2020 6:11 pm
I also made burners for kerosene, but I had a particular situation.
I wanted high and controllable heat output for a long period, to fire heavy ceramic sculpture.
We were living in India, and although we had electricity, it was very unreliable. In fact, the only thing you could depend on for sure was power cuts.
Gas was precious and hard to get.

I built a downdraft kiln with an 8' chimney, that had good draw. Too good, I had to pinch off the flow with firebricks on top when it got hot.

There were 3 generations of burners, and the last ones worked really well. I used an LPG tank for the fuel, and pressurized it with a small compressor, or a 12v one if the power went out. Starting at 10psi, finishing at 100psi for full output.
I bought factory made pressure stove heads for preheat and ignition, they would burn just to vaporize the fuel for the main burner jets.

Later, I added a programmable controller than ran on an inverter + battery backup.
I can't remember the numbers, but these things cranked out a lot of energy. It could be heard at the other end of the village, sounded like a rocket engine. 30 liters of fuel was required for a full burn, ending at 1000 C, that's 1830 F

Long ago, I made a webpage with pictures if anyone cares; http://www.amsterdamhouseboats.nl/press ... burner.htm
I read the information at your link, and everything you say agrees with everything I have learned about burners.
There was a lot of experimentation online with burners around 2000 or so on forums, and one thing I read was that fuel in preheater fuel lines tends to clog up in furnace applications, although I know it is used successfully in other applications.
I suspect that fuel preheater lines will clog if overheated, but if the fuel is not overheated, the fuel line would not clog.
Diesel does not need to be preheated to start or operate the burner, and I don't know of any advantage to preheating diesel if an atomizing nozzle is used (perhaps it would make sense with a non-atomizing type burner).

I can tell from your page that you have done a lot of experimentation and research regarding burners.
There are a lot of burner types out there, and many of them have degradation issues from overheating the burner tube, as you mention.
I measure the usefulness of a burner as follows:
1. Consistency (burner can be lit and does not need any adjustments during the burn).
2. Reliability (the burner never needs maintenance, or perhaps an occasional cleaning of the nozzle tip to remove varnish).
3. Maximum temperature that can be reached (I melt iron, and so I need a burner that will produce a lot of BTU's).
4. Clean burn with no visible smoke.
5. Ease of lighting the burner (burner is easily lit initially, or easily re-lit if turned off and then on again).
6. Flexibility (the burner can be used with waste oil, veggie oil, diesel, or propane; and the burner can operate over a wide range of fuel flow rates).

.

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PatJ
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Re: Oversized Stainless Keg Furnace Build

Post by PatJ » Tue Jun 23, 2020 8:40 pm

The Ursutz burner has been around for a long time.
There was one article about it in a magazine from the 1950's I think.

The Ursutz starts the combustion process in a chamber that is outside of the furnace, and exhausts partially burned but very hot fuel/exhaust gasses into the furnace via the tuyere where a typical burner is installed.
The Ursutz burner needs to be made from a high temperature refractory in order to survive any length of time.
They tend to be bulky and heavy, and can work too well; ie: the hot gasses can damage the crucible and plinth in a very short period of time.

.

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liveaboard
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Re: Oversized Stainless Keg Furnace Build

Post by liveaboard » Wed Jun 24, 2020 4:24 am

I made those burners around 25 years ago; maybe 30. There was no internet, so I pretty much had to work from whatever I could find and figure out myself.
I had a book [remember those anyone?] that showed atomizing burners, my trouble was the power supply was extremely unreliable. Aside from the voltage bouncing up and down all the time, it would just fail completely for a minute, an hour, or a day.
Also, only the most basic materials were available there at the time.
So I developed the system to use heat-vaporized fuel and convection.
In later years, I ended up adding my own battery / inverter backup power for the house and I realized that a blower system was then feasible, but I already had the vaporizing burners and they worked.
I had an automotive diesel filter in the line, and the jets would clog on occasion. Not too often. I used a little wire to clean the jet as necessary.
The burners had side access ports for that.

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