Anyone tried Reverse Vortex Flow on their crucible furnace?

Discussion in 'Furnaces and their construction' started by Preston Smith, Feb 2, 2022.

  1. Preston Smith

    Preston Smith Copper

    In some other work I've done, I studied a type of non-thermal gliding arc plasma generator that used reverse vortex flow to achieve several things:
    • increased gas residence time
    • thermal gradient (cool on outer wall, hot in the core)
    • increased fraction of gas in plasma arc
    Basically, if we moved the tuyere to the top, just under the lid, the combustion flow should go down the wall and then reverse course by spiraling up out the vent through the core. A similar effect can be achieved in a vortex tube by closing the cool end outlet.

    The primary benefit for us may be to increase residence time for more complete combustion/thermal transfer. May also reduce the thermal load on the refractory walls. Thoughts?
     
  2. Billy Elmore

    Billy Elmore Silver

    I have a three piece furnace with the center being reversible. It would not be very hard to try it in that set up. I may do that one day and see what transpires.
     
  3. Melterskelter

    Melterskelter Gold Banner Member

    Hmmm, why wouldn’t the combustion gas just take the shortest and easiest path up and out the vent? There must be a few more bits to the configuration you are proposing. When I look this concept up what I see are empty chambers with inflow and outflow paths that don’t seem to have anything like a crucible occupying the main area that would be used for reverse flow. So it makes me wonder how this process would work in a furnace with a crucible occupying 3/4 or 4/5 of the central area. Have you seen a combustion chamber comparable to our furnaces utilizing this concept? I do see proposed cyclonic separators set up this way and experimental plasma generators similarly setup.

    Denis

    Denis
     
  4. Jammer

    Jammer Silver Banner Member

    I built a furnace with extra space around the base for the gases and flame to go around before going up. Seemed to work well, I melted about 6 pounds of Cast Iron with propane. It's a little large for what I need, I think it will hold an A-20 crucible. I called it "Big Boy". Someone else called it a top hat furnace because of the shape of the inside. I cast an inner shell with High temp Refractory and packed Insulation around the outside. Then capped it off with refractory.

    IMG_2131.jpg IMG_2136.jpg IMG_2141.jpg IMG_2144.jpg IMG_2145.jpg
    IMG_2131.jpg
    Cast 08-11 002.jpg
     
    Last edited: Sep 12, 2022
    Tobho Mott and _Jason like this.
  5. garyhlucas

    garyhlucas Silver

    My MIFCO furnace doesn't port the exhaust out the top. It goes out the next quadrant from where the burner is at the top so all flame goes around not over the crucible. It has a large lid that can be opened upwards and rotates out of the way. A smaller lid has a 1" center hole. When the furnace is fully firing during heat up very little heat comes out the top. In fact I have taken to setting a stainless kitchen bowl in the large lid opening blocking it off completely. I preheat metal going in furnace in that bowl getting back a lot of BTUs and shortning the melt time. Also eliminating a bad splash from dumping water into molten metal. The stainless pot sits right on the crucible sealing off air except when adding charge. Not having experience with any other furnaces this all just seems right with the world.

    Damn FireEye has died and this thing is at least 40 years old.
     
  6. Here's a diagram of an oil burner from the 1940's that Sir Frank Whittle found was the ideal compact high volume burner for his early jet engines. It has static swirl blades (item 4) near the oil nozzle (item 3) and precombusts and gasifies the fuel around (item 5) before air is added (item 6) in a reversed swirl that goes backwards to (item 7) for full combustion. The chamber (item 5) looks like those sawdust extraction cyclones in shape.

    oil burner.png
     
    Last edited: Dec 16, 2022

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