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will a solid steel ribbon burner work ?


BartW

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hello guys;

 

I have a question concerning ribbon burners. I've seen how most are made; and all cast a block of refractory cement with straws or some other means of making holes in it; then attach it to a metal casing in which the gas/air mix is pushed, most often by a blower; but it's also possible naturally aspirated. In my position, I got plenty or basically any kind of steel/ iron / cast iron. But refractory cement ... is fairly pricy, especially the good stuff.  

Now suppose I don't feel like mixing refractory cement, and replace the hole-block part with a 1 inch thick cast iron plate full of holes... or 2 inch .. or a mild steel plate. Of course, I'm going to make sure that plate doesn't touch the metal box in the back to limit heat by convection by separating it with a insulating fibre board rated for verrry high temperatures (1260 °C) . The cast iron gets "cooled" on one side by the cold gas/air mix; and heated on the other side by the inside of the forge.

This limits the cracking problem with casting refractory. And replacing the face plate when it's worn is not really a problem; 10 minutes with an angle grinder, and 20 minutes on a drill press. Also, my forge is mostly used on weekends, and I really like the "silence" of ribbon burners, as opposed to the roaring of my current venturi burners.

Is that even possible ? Or is this a bad idea for some reason I'm missing ?

mvg; Bart

 

 

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With the caveat that I am very much not an expert on this stuff, I suspect that you would get issues with scaling and warping of the metal, possibly even with the metal burning up. Keeping a gas-tight seal between the plenum and the flame face would be difficult if you had insulating board in between. As someone said, "If there's an obvious and easy solution, there's probably a good reason that people aren't doing it."

I would still recommend casting the refractory block. It may be a bit more pricey up front, but worth it in the long run. If you only have weekends available for shop work, would you rather spend that constantly maintaining and repairing your burner, or forging?

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If you go down to your local pottery supply store and buy a bit of 1" thick kiln shelf, it can be cut with the right kind of friction blades in an angle grinder, and it can have holes cut in it with the right kind of carbide drill bit. And if you use a little bit of refractory cement to cement the insulating board onto it with, you could end up with a workable solution. Or, you could just buy a much smaller amount of castable refractory from Wayne (a member of our group) and build your ribbon burner for a lot less time and money :)

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  • 7 months later...

In general the surface of the burner block is roughly the same temperature as the rest of the forge chamber in normal operating conditions.  My ribbon burner is recessed a little from the rest of the forge chamber, so there may be a slight difference but it's not significant.  I drilled holes in an insulating firebrick rated for 2300 degrees F and used that for my burner head.  I managed to melt (or at least vitrify) the IFB when I had the forge cranked up high.  I'm not sure of the temperature I reached, but I would guess it was over 2500 degrees in order to have that effect.     Even if the steel in your burner head didn't actually melt or burn up in a shower of sparks, it would be glowing hot and slowly transfer the heat backwards which would almost certainly result in ignition inside the plenum eventually.

Of course I could be wrong and you could try it and report back, but imho that approach would be problematic very quickly.  I also strongly suspect that if it were a viable solution not very many people would want to take the time to create molds and all the hassle that goes with casting compared to drilling and welding.

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Maybe IF you use a rocket engine alloy. Have a piece of: Monel, Incanel, etc. handy? I think un-coated steel or SS would be pretty short lived.

You might contact ITC though, they make products other than ITC-100, some intended to wash steel or other metals in contact with furnace interiors. They MIGHT have a product that will work for you.

Frosty The Lucky.

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Building on this a little...how laminar does the flow through the openings have to be in a ribbon burner?  The O.P. was thinking about a slice of perforated steel---but because I happen to have  diamond rock saw blades around anyway, it got me thinking (dangerous, I know)

If one were to take a piece of cut-to-size kiln shelf and do a series of groves with a diamond saw on one side roughly 1/4" apart, followed buy a series on the other side  perpendicular to the first--deep enough that they just barely cross into each other at the mid point...that leaves one with an effectively perforated piece of high temperature alumina with roughly 3/32" squarish holes on 1/4" centers (depending on blade and spacing).  At issue is whether holes like that will create burn problems or not due to turbulence or the grooves on the exit side or whether that might actually be of some benefit.

Sorry--just something that crossed my mind which might make a longer lasting burner front plate..or one that can be replaced more easily (make 2 since you are already doing the saw set-ups and likely have extra material to begin with).  I estimate total time to be about an hour which is far less as well as far less fiddly than casting.  But again, it's tooling I already have anyway.

Of course the above is a bit oversimplified because you have to consider sealing it into the mount too...

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Interesting thought Kozzy. I'd be wondering how the pattern would effect heating and expansion.

Increased surface area on the fire side would cause it to absorb IR at a higher rate wouldn't it? Coupled with the increased area on the plenum side's increased cooling rate I can envision some strange expansion differentials at work.

Worth a try is you have the gear and time though. We'll work out something to seal it to the plenum. 

Frosty The Lucky.

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A problem with using a solid steel or cast iron block for a ribbon burner is heat transfer. As the furnace interior warms up, heat is transferred through the hot faces on the inside of the furnace to the exterior faces where it is dissipated to the environment. Refractory materials in general slow this transfer of heat such that:

1. Enough heat is kept inside the furnace to allow it to reach forging temperatures.

2. Only a small amount of heat travels through the hot face wall to the furnace's exterior and this small amount of heat can be easily dissipated by the surrounding air; keeping the exterior of the furnace relatively cool.

Now replace a section of the hot face wall with a modestly sized ribbon burner block. This block is going to absorb heat, this heat is going to travel through the block until it reaches the plenum on the other side. The biggest thing cooling the ribbon burner is the flow of air through the block into the furnace. With a refractory the flow of heat through the ribbon burner can be offset by the air flow.

However, steel and cast iron have much better heat transfer than refractory and this means the air flow alone will not be enough to keep the plenum side of the burner below the ignition temperature of the propane/air mixture on the plenum side. The result will be a detonation and fire on the wrong side of the burner. 

How do I know this? My first ribbon burner forge experienced a fire on the wrong side of the burner when operated incorrectly (by me). The burner in question was made out of a hard refractory cement The forge was being being run very hot to do some forging welding for about half an hour. When the welding was done I turned down the air/gas flow to reach a normal hot working temperature. About five minutes later I heard a loud boom and then had fire coming out of places it shouldn't have. No one was hurt and but the blower fan was trashed from the detonation. The problem was the heat stored in the burner's refractory during the high temperature run. As long as the higher temperature was balanced by high air flow things were fine, but with high temperature and low air you get fire in the wrong place.

My new ribbon burner has a water block build into the plenum side of the burner to prevent this.

Steve

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I'LL let ya's know how long the steel on a ribbon burner will last without refractory i'm doing a test now.I built mine out of a 2'' pipe coupler and a 1/4 plate welded to it with 25 1/4 holes drilled in it so far so good.I have been running it everyday since i built it at forging temp on 5 psi for 3 to 4 hours a day  for the last four days no problems so far .The only thing i do to protect the plate is run the fan for 3o mins to protect the burner from the residual heat after i shut er down. I check the burner every 10 mins with a heat gun when its running and it gets between 125 to 300 deg were it sticks out the forge so about 2'' from the tip.I checked the bottom of the burner in the forge with a mirror to see if the holes were ovaled or showing sighns of burning out so far nothing actually the remnants of the the drilling are still around the edges of the holes.

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  • 4 years later...

It shouldn't be a problem.  You will most likely not be reaching temperatures greater than 500 F in the cooking chamber.  I don't think that will cause problems with either premature ignition or excessive degradation of the burner surface. 

In a forge we are sometimes reaching temperatures in excess of 2300 F, so the burners have to be able to withstand that heat for hours at a time without failing.

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Yes, no problem. Burners in gas ovens are almost always multiple orifice burners, "Ribbon" is just a description of one shape multiple outlet / nozzle / orifice, etc. burner.

Frosty The Lucky.

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Americano

Welcome from the Ozark Mountains.

I read on a blog about pizza ovens a couple of years ago that they were building them with reclaimed home furnace burners that were steel or cast iron. When we had to have our furnace replaced I saved the burner & gas regulator, planning to build a pizza oven. I still haven't gotten arountoit though. If you are close to me stop by and you can have it. If you are on the other side of the planet, check with some HVAC places that work on furnaces, most here will give you more burners that you can carry.

I can't control the wind, all I can do is adjust my sail’s.
Semper Paratus

 

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Thank you so much. I would love too! I live in sunland California. I've build several venturi burners and several pizza oven with it. But venturi consume a lot of propane. I've build a barrel style pizza oven recently is probably 65 inches by 48inches cooking surface.

 

I think I need 2 ribbon burners. I am very familiar with pipes welding and all that. My questions are 2 how long can effectively be a ribbon burner? 

Can I make one 2ft?

And like I said I think if the burner is not upside down like in a forge , It can be made out of metal only what do you guys think?

 

Thank you for the help.

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Sunland, Ca. no kidding? I grew up in Sylmar about 1.5 miles from the San Fernando Mission.

Multiple outlet burners can be very long, there was one under the asphalt pan on the patch truck that was 6' and it was smaller than the ones under pavers. 

It'd take a little tinkering but I'm pretty sure I could make a "ribbon" burner to heat a Shakey's sized pizza oven. 

About fuel efficiency vs. effectiveness. Efficient just means how completely the fuel is burned, stoichiometric being complete combustion of fuel and oxy. Effective means having a fire that heats a volume or object enough without waste. A naturally Aspirated (NA) or venturi burner will use the same amount of fuel as a single nozzle or multiple. Where multis are more effective is the flame velocity, the slower the flame the longer it stays inside the furnace transferring energy to the furnace / oven walls to radiate IR to work for you.

Make sense?

Frosty The Lucky.

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