Best Burner For Larger Furnace

Hello all. I am going to be making a larger furnace in hopes of melting at least 75 lbs of aluminum so I can do some permanent mold pouring. I’ll be making another thread for that one. I have a few questions on burners.
- What burner is the most efficient while running at temp?
- Drip feed or injection/siphon? I’d like to use waste oil, but have the option for diesel if I can’t find any/runout of waste oil.
- I’m fine with using propane to preheat the furnace if needed.
- I have an air compressor so that isn’t a problem, just looking for input on what would be the best/safest way to melt.

I may have just opened up a Ford/Chevy/Dodge debate, but any input you could give would be appreciated.

 

Oh and what are everyone's feelings on the burners that NOBOX7 on youtube has? There are several sizes, but here is one of his quick youtube videos.

 

Thanks for the input. A couple more questions.

• Can the drip burners run on diesel?
• What style burner would be able to be throttled the easiest/ best for attempting to hold temp for dipping out?
• Are either better for running indoors with proper ventilation?

 

I won't join in too much as I just have a little toy burners. But here's a good thread to read through. Near the end Jeff does a pretty good video.

http://forums.thehomefoundry.org/index.php?threads/larger-moya.780/

 

They can run on anything that burns as far as I know. Most folks I've seen using them burn waste oil because they value the simplicity and bulletproof nature of the burner plus free fuel.
Having said that, I run a siphon type nozzle for now but have been thinking about building a brute for grins. I have a pressurized tank so measured delivery is no problem and it would save wear and tear on my compressor. It seems like it should be easy to throttle if the fuel is being pumped or pressurized. Gravity fed seems like it would be less easy due to variation in head pressure as the tank level gets lower.
The siphon nozzle is very easy to adjust and hold at a given setting but again my tank is pressurized so at this point the Venturi effect (which is actually how they work in their intended application) is pretty negligible. For the record, I have never been able to light my Delevan burner from a cold start with heavier fuels like waste oil or veg oil. I always preheat with either propane or deisel and then switch to WO.
So I still don't think there's a clear winner here. One things for certain though. Variations in your fuel's viscosity will require some variation in your settings. Burning deisel or kerosene gives you repeatability. Waste oil can be different from one day to the next depending on temperature (and whether you've dumped gear oil in your tank recently). It's not a deal killer. It just requires a little more fiddling.
There's been some good discussion here recently regarding ventillation. Maybe someone can point you there.

Pete

 

JKlein what type of blower have you decided on? Or have you? At the size of the furnace you're building, I think you're going to want a reliable motor on the blower. I'm sure my big blower on a VFD would suit all your needs. My blower brand new is almost 1000 USD and the VFD 275 USD. Maybe a leaf blower would work, but I would keep one or two extra on hand.

From your 100 pounds of aluminum goal with waste oil I'm guessing you were going to need a 20×24" inside diameter furnace. That is pretty much 3x the size of mine. My furnace will almost fit right inside yours. I might be able to do 3 1/2 L of aluminum where you're looking at over 20 L of aluminum. Now you're 5 1/2 times the amount of aluminum. Let's just say for shits and giggles it takes me a half hour to melt 3 1/2 L of aluminum using a 1/2g of diesel and 1 1/2 gallons of WVO. Using the same numbers it's going to take you 5 1/2 times longer to get the melt or you're going to have to put 5 1/2 times more fuel and air to achieve the same melt in the same amount of time. I am being very conservative, as your crucible thermal mass density will weigh more than my crucible filled with aluminum.

I got some things poured at a medium size foundry that has a capacity of 30,000 pounds of cast-iron. They told me if they're doing over 20,000 pounds they start firing the furnace around seven or 8 o'clock at night for a 4 o'clock in the afternoon pour the next day. Most days they are pouring 10,000 pounds and they fire up the furnace at 5 AM for a 4 o'clock pour time.

 

when the guy can show that he can melt and pour 1 L of aluminum or anything he might have some credibility. One of the last videos I saw him do was he used one of his new torch tips and let cast iron solidify. Then try to show it as an information video. I think his customers are getting bamboozled.

 

Thank you all for the input. Definitely giving me much more information to think about. I don't have a blower yet and would get one appropriately sized for the burner/furnace. Going to do a little more thinking and see if I can live with a smaller furnace. Thinking that I start a little smaller with an A60 size crucible, but I'll have to think about that a little more.

 

I personally think if you got into A20-40 you still would not be able to keep up as a one-man team. In less than one hour you could be pouring over 1 L of aluminum every 10 minutes.

 

The reason for the 75 lb number is just so I have enough capacity to run plenty of parts off the permanent mold machine to justify heating the tool up to 900 degrees. For what I currently have, I would definitely be able to make 50 lbs work as its only about 1 lb per pour. For this thin walled part, I can cycle the machine about every 45-60 seconds so you can go through metal pretty quick. The kicker is the crucible opening has to be large enough to be able to dip out of.

 

If you are only melting aluminum, a siphon burner running cheap diesel, kerosene, jet fuel is all you'll need. It's clean, easy and not temperamental to temperature changes. I once fell for the allure of massively cheap FREE used motor oil. I had no problem running the stuff, but it flows differently from month to month and I got sick of dealing with the mess. You are in Michigan so if you choose to utilize black goo, you'll want to consider preheating your oil to the same temperature year round. This will help you dial in your mixture consistently if it's 80degrees or 35degrees. Not a big deal, a small electric heating setup on a thermostat to keep it at a nice warm 90degrees should keep things flowing nicely. A siphon burner will help you maintain some kind of regularity and it offers precise control instead of just "balls out".

Look up the kwiky siphon burner for a home build method. A more professional version is the hago delevan siphon burners. None of these are expensive and I'm sure you own an air compressor at this point... Siphon burners don't draw massive amounts of air and a halfway decent 60gal tank will keep up with the demand just fine. Mine runs once every 5-7mins and then only for about 1 minute at a time. Nice and easy duty cycle.

 

A bottom fill ladle might be a good solution.

 

Jklein sometimes small torches can be powerful too...

 

Clearly the guy with the stainless burner has no clue about the Bernoulli principal works, which you can tell because it is spitting not vaporizing.

 

My little stainless steel burner syphons, and will pull a water column. Mine spits like crazy at half a litre a minute. I would say mine has Bernoulli's principle. Can you share your opinion on how Bernoulli's principle is not applied?

 

The one pictured has a Y which works but very inefficiently because there is no velocity increase at the point of liquid introduction. Bernoulis principal is that as velocity increases pressure decreases. So you want a nozzle that increases the air velocity and the feed point is at the point of highest velocity.