Olorin Posted June 16, 2023 Share Posted June 16, 2023 I know there are forums on popping forged already, but none of them I’ve seen exactly describe the issue I’m having. My forge is a ribbon burner 2”x4”x14 1/4”, an interior size of about 3”x18”; when using the forge it lights up and runs beautifully, but after a minute or two it pops loudly and the flame goes out. I can’t think of any reasons it would be doing this, there are no cracks in the burner, the pipes are brand new, the refractory is solid. Does anyone have any ideas? I’ll post the video if it will let me. IMG_2207.mov Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 16, 2023 Share Posted June 16, 2023 It's blowing itself out because you have it in WAY too small a forge causing the burner block to super heat and when it hits the temperature the rate of propagation exceeds the flow speed it burns back into the plenum. Listing a string of linear dimensions isn't helpful. Burner requirements for a forge are based on Forge VOLUME, not it's diameter, length, etc. I don't do simple math anymore. I rarely respond to these at all. However I'm familiar with the problem, I wrote about it the causes and solutions in the NARB Lives thread. Didn't read it though did you? Think about it, your forge is 6x as long as it is in diameter, your burner is 2/3 as wide as your forge's diameter and about 80% as long. Half the refractory lining in your forge is the BURNER! That burner would fit a 6" dia. forge much better. I can NOT think of a fix for what you have now. In mine I increased the flow rate to keep the burner block cooled below the flame face velocity, even then it starts burning back in about 4-5 hours and I have to shut it off for a couple few hours to cool. As built yours WILL burn back at a much lower temperature because it's in such a small volume, the back pressure almost forces the flame back against the flow. It's also too narrow to turn the flow up to cool it because the back pressure will just increase beyond function. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 16, 2023 Share Posted June 16, 2023 40 minutes ago, Frosty said: because the back pressure will just increase beyond function. And that's when its time to start all over again. There is no finessing our way out of a mess. Quote Link to comment Share on other sites More sharing options...
Olorin Posted June 16, 2023 Author Share Posted June 16, 2023 Ok, no need to be rude about it I’m still new to making forges. I’ll keep that in mind and start again. Quote Link to comment Share on other sites More sharing options...
Latticino Posted June 16, 2023 Share Posted June 16, 2023 Afraid I must respectfully disagree with my colleagues on this one. Looking at the video it appears you are running a blown burner with a multi-port burner block. I do agree that the burner may be overkill for the size of the forge interior (as I have posted before, there is a minimum forge volume that burners can tolerate for full development and effectiveness of flame), but I'm not certain that is what is going on here. The flame with the forge quite cold looks like it may be already lifting off the face of the burner block. This is an unstable burn condition. I recommend starting heating your forge at a much lower air/gas mixture flowrate (choke the air and reduce the gas pressure with your adjustable regulator) where the bottom of the flame stays properly attached. Try turning it up only after the forge begins to glow. This may not solve the issue, but it will at least give you more data points. You may also want to tweak your air/gas mixture proportion. At least worth a try before you give up on the forge. Also, are you certain the refractory is fully cured? If it is still outgassing you could still have a problem related to that. Quote Link to comment Share on other sites More sharing options...
Olorin Posted June 16, 2023 Author Share Posted June 16, 2023 Latticino it is not fully cured, I was unaware that would cause a problem. I have a section to choke down the air flow a little more and I have a better regulator to attach to the forge, so I’ll try that when I get a chance. Thanks and by not fully cured I mean heat cured just to be clear! If I get a blower with a variable speed to reduce the amount of air going through and reduce the PSI of the propane do you think that would help? Quote Link to comment Share on other sites More sharing options...
Latticino Posted June 17, 2023 Share Posted June 17, 2023 Start by heat curing the refractory. In that size forge outgassing during curing can be a problem (particularly in your burner block). Variable speed can be a little difficult to achieve depending on motor type. Waste gates are easier. Still you definitely need a method of modulating both the gas and propane flowrates. Another potential problem is if you don't have enough of a door opening to exhaust the fumes (combustion products). I don't think this is an issue for you, but it is hard to tell. How does the burner operate outside the forge? Quote Link to comment Share on other sites More sharing options...
Olorin Posted June 17, 2023 Author Share Posted June 17, 2023 (edited) I didn’t test it outside the forge, something I regretted after putting it in; I had meant to but I got excited to finally be done. I was looking at a variable speed motor on Amazon that might do the trick, what’s the optimal flow rate for a ribbon burner forge of this size would you say? For air and gas flow Edited June 17, 2023 by Mod30 Remove @name tag Quote Link to comment Share on other sites More sharing options...
Purple Bullet Posted June 17, 2023 Share Posted June 17, 2023 I once made a blown ribbon burner by welding a 1/2" square bar to a 3/4" black iron pipe and drilling a bunch of 1/8" holes. My blower was a shop blower from Tractor Supply that I put a rheostat (dimmer control) on. The gas went through a solenoid valve and I had a decent regulator. The solenoid valve was tied into the same circuit as the blower so that if I lost power to the blower the gas would shut off. With this set up I was able to control the flame to a Tee. I never had a problem with anything burning out and could get to welding temperature. I only tore it apart when I got worried about breaks in the refractory exposing ceramic fibers. I've learned better ways to deal with that now, but I was moving to induction anyway. Quote Link to comment Share on other sites More sharing options...
Latticino Posted June 17, 2023 Share Posted June 17, 2023 1 hour ago, Olorin said: what’s the optimal flow rate for a ribbon burner forge Sorry, that is easiest figuring from testing. A lot would depend on your burner configuration, gas port size, location of your pressure gauge, mixing tube size and length... Then I'd have to do the combustion calculations, and that is too much like work. I'm afraid when you build a custom burner a certain amount of personal experimentation is required. Quote Link to comment Share on other sites More sharing options...
Olorin Posted June 17, 2023 Author Share Posted June 17, 2023 I see, understandable! Thank you for your help. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2023 Share Posted June 17, 2023 Olorin the forum OS doesn't recognize the @ tag it only causes problems the mods have to chase it down and remove it by hand. It's not too late to delete the one above. If you'll read back to your post before the one above you'll see the note from the mods about removing THAT @ tag. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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