Glumpy burner, easy to run!

Discussion in 'Burners and their construction' started by Ironsides, Jun 1, 2019.

  1. OMM

    OMM Silver Banner Member

    Thanks Pat for the video. I somewhat figured the burn chamber would’ve been a little larger in diameter and a little taller.

    From the video I am estimating it to be about 4”ish diameter, and maybe 10 inches tall. He has a pretty good design. I’m wondering if he has designed it on the inside to Vortex.
  2. Petee716

    Petee716 Silver Banner Member

    What I was driving at pertains to the question of crucible clearance in the furnace bore i.e. "How much space do I need between the wall and the crucible?" The usual response for an oil burner is 2", less for propane. Reason being that oil needs more space for combustion. However with the burn occurring in an external combustion chamber that space is no longer needed for cumbustion in the bore, which might very well allow for a larger crucible than you would normally use in the same size furnace. It's understood that the crucible must be elevated to avoid impingement regardless of where the oil is burning.

  3. PatJ

    PatJ Silver Banner Member

    I have never considered that aspect of it.
    Clarke has had multiple plinth failures, but I can't state exactly what is causing that, but I can say I have never had a plinth failure during 46 pours of aluminum/bronze/iron.

    I really don't like a tight furnace because the lifting tongs can strike the wall, etc., and I just like some elbow room.
    I like a minimum of 2" clear around the crucible when using the largest crucible I intend to use with the furnace (for me a #30 and that gives 1.94" clear).
    Note that crucibles are curved on the sides, so when I say 2" clear, than means 2" clear at the top of the crucible, and thus there is more room as you go lower in the furnace.

    I would be afraid that a tight furnace would direct too much heat onto the crucible.
    Can't really say for sure what would happen since I have never tried a space less than about 2".

  4. PatJ

    PatJ Silver Banner Member

    Don't go by Glumpy's videos as far as size and such, since Glumpy does not use his burners to fire crucible furnaces as we do.

    You are not trying to launch a Saturn V rocket, you just want to melt a little iron.

  5. OMM

    OMM Silver Banner Member

    I see exactly why he is having plinth failures. He’s using the bottom side of his furnace as a secondary burn chamber. I bet you his plinth are sitting on top of 2 9 inch bricks. That video showed the crucible 4 inches above the lid. The crucible looks to be maybe 10 inches tall. His burner enters about 6 inches from the bottom. In my guesstimate, there’s got to be about 12-16 inches of burn swirling underneath his crucible.
  6. PatJ

    PatJ Silver Banner Member

    It seems to help with iron melts to have the crucible as high as possible, and so I keep mine elevated to within perhaps 2" of the lid, or a little less.
    The lower part of a furnace is the coldest when using a standard drip/siphon burner.

  7. OMM

    OMM Silver Banner Member

    But if you’re having white flames that far under your crucible, The crucible becomes a big stop.

    I guess you could probably test it by putting a dish type crucible that’s 12 inches off the bottom of your furnace and then cranking the heat up
    Last edited: Jun 3, 2019
  8. PatJ

    PatJ Silver Banner Member

    That is a new term to me.

  9. OMM

    OMM Silver Banner Member

    In the modern era, I guess we all do typos and double posts. I think computers have a mind of their own sometimes. :rolleyes:

    Edit; I did a the edit to please you. I also got the double post removed to please you. You’re a tough cookie!
    Last edited: Jun 3, 2019
  10. oldironfarmer

    oldironfarmer Silver Banner Member

    I try to direct my flame below the crucible. Not sure what a plinth failure is. I guess I've had three plinth failures. Two of them Greencast 94 and one soft firebrick. The first hard refractory plinth lasted perhaps 200 melts, the second one around 100 melts. No falling crucible with either, just continued cracking until it seemed prudent to remove it. Then in a hurry I set a soft firebrick piece in and it lasted probably 30 melts and cracked in two. So I'm on my second soft brick plinth with around 20+ melts. I think I'll stick with soft firebrick until I run out of leftover pieces. I just passed 350 heats on my "simple" brick furnace.
  11. Tobho Mott

    Tobho Mott Silver Banner Member

    I've noticed that in 3 heats my oil burner has somewhat blackened/burnt the side of the 3200F dense castable plinth I borrowed from the big furnace. It's sized for my #12 crucible but has been getting used with a smaller one I was given by my blacksmith friend once we got done pouring that condenser coil, since it is too big to fit in his forges anyhow. The new furnace has a narrower bore, so the edge of the plinth is sitting closer to the burner flame. My Satanite arrived yesterday, so maybe I'll give it a coat of that, to take some of that damage the plinth has been soaking up.

  12. Melterskelter

    Melterskelter Silver Banner Member

    I think Satanite is good for everything, Jeff

    On my next plinth I’m going to cast it with a joint line which will be a piece of heavy paper like the back of a note pad. The paper will be set to coincide with one radius of the plinth. My reasoning is that I suspect plinths pull themselves apart due to differential heating and cooling. The expansion joint will be an attempt to go with the flow so to speak. It makes little sense to ask any refractory to withstand the rapid and asymmetric heating a plinth must endure.

  13. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I did something similar on my large furnace refractory. The flanges are insulating castable and the barrel is dense castable refractory. I used a couple layers of tape between the ring and the barrel. The barrel is still mechanically captured by the rings but with room for expansion of the barrel before stressing the rings.

    4 Main Body and Bore.jpg

  14. Tobho Mott

    Tobho Mott Silver Banner Member

    Maybe I'll start taking a teaspoon in my coffee every morning and see if the wife notices any improvement. :D

  15. oldironfarmer

    oldironfarmer Silver Banner Member

    Warning! It gets stiff and hard and stays that way.

    Is it soot on your plinth? Is it heavy enough maybe it's not getting hot enough to burn the soot off?
  16. Tobho Mott

    Tobho Mott Silver Banner Member

    No, looks more like the refractory is actually burning a little bit IMO, I'll get a pic when I get home.

  17. PatJ

    PatJ Silver Banner Member

    I coated the interior of my furnace with ITC100, but forgot to coat the plinth.
    I appears that what is happening is that without the ITC100, the refractory (Mizzou) begins to chip and fail on the surface due to the heat.
    It is very small chips, but over time it will add up.
    The chipping may never add up to a significant problem, or it may be a sign of larger problems in the future.

    The ITC100 does stop all the chipping, and the surfaces that were coated with ITC appear to have never seen any heat, and are perfect.
    ITC100 has become too expensive for me to use, so I guess I will try Satanite.

    Photo attached.

  18. Ironsides

    Ironsides Silver

    Are you going to ignore my burner? It has been melting iron since 1996 and it works so well I have never seen a need to change it. ( lost count as to how many melts it has done. )
    Chazza and oldironfarmer like this.
  19. PatJ

    PatJ Silver Banner Member

    I didn't ignore your burner type.
    I stated that it works well (see statement above).

  20. Ironsides

    Ironsides Silver

    You should revisit the drip style burner like mine as it is so easy to operate.
    oldironfarmer and Tobho Mott like this.

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