Propane ribbon burner hot enough to melt pig iron?

[jacobball2000]

I am around 10 to 15 psi. I might have to back that down or open the orifice a little. I have a number 19kg and 24kg crucible but there graphite/clay you're the same?

 

[CrashedAgain]

My crucibles are silicon carbide, I've had them for years. Nothing wrong with graphite/clay, though. The size number designates the capacity of aluminum in lbs., so the # 8 will do 8 lbs (note...not kgs) of aluminum or 24 lbs of bronze.
24 kg (52 lbs) is a BIG crucible, what are you making?
I was making sculpture, the #8 would easily do a full size head & shoulders bust in one pour and the old furnace would do a melt from cold in about an hour. Lately, though, I have just been making small model engineering projects.

 

[jacobball2000]

Right now I am melting Aluminum and building steam engines. I want to work my way up to steel but for that I need to make a new furnace the one I have now won't last long at those temp's. My clay crucible has crack in it but it seems to still be able to work. I remember in high school the crucible there was made of ceramic but they cost a lot. I just found out that the Silica flour that I bought can handle temp up t0 3116 f and I have fire clay that handle 2800 f the problems I been having with fire clay is cracking. I now know this is do to thermal shock. but the silica flour turns to glass once heated. This might fix my problem of trying to get high temp with out Thermal shock.

 

[master53yoda]

As i expalained in another thread, the flame temps most often quoted are a perfect mix of air and fuel with 0% excess air. In reality any of our burners will have some excess air, this excess air reduces the delivered flame temp. Weed burners normally draw as much as 200% excess air as thy are trying to create a physically large flame front that only needs to have a flame temp of about 800F to get the fuel (Grass) above its ignition point. When firing into a closed or restricted environment like a forge or furnace the burner experiences a back pressure that reduces the amount of excess air the burner draws. Sometimes enough that the fuel mix velocity is low enough that it ignites before it ever gets out of the burner. By using a forced air burner with controlled air flow you can get the flame to remain above the flame rate so that the flame sets right at the exit of the burner. What a flare does is gives an increase of area at the end of the burner that allows the velocity to reduce enough to burn without the back pressure created in the furnace.k I personally use a larger burner and a plate at the end of the burner with holes in the plate that creates a high velocity at the plate, this reduction in velocity as the fuel mix goes through the plate with retain the flame front right at the plate. it also allows me to control the amount of excess air to as little as 10 to15%. Which will give a flame with enough temp and btu capacity to melt iron.

With out a lot of experimentation and luck it is possible to accomplish the same thing with a naturally aspirated burner, but it would not work at any elevation different from where it was tuned as the atmospheric pressure is providing the air pressure that the blower does in a forced air furnace.. Commercial burners all used forced air burners with variable air flow to deal with this issue. residential furnaces using ribbon burners etc. reduce the fuel orifice size at above 2000 ft.

Art b