Naturally Aspirated Ribbon Burner. Photo heavy.

[JADF]

3 hours ago, Frosty said:

To get the scaler or impact drill to work I clamped the forms to a steel plate and vibrated the plate. LOUDNESS!

That's what I tried, obviously with no more luck than you. Once I cut an inch off most of the dowels came out pretty easy. I'm going to have to try again eventually, maybe I'll be the guinea pig for the twisted candles, does sound interesting.

[Frosty]

Vibrating is worse than doesn't work, the vibration literally locks the particles together bridging the narrow spaces between the crayon cores. I discovered after vibrating I couldn't force a putty knife between the crayons, I had to make a flat tipped knife then used a hook dental probe to lift and loosen the aggregate. 

Getting Kastolite to fill between the cores completely is my least favorite thing about it.

Frosty The Lucky.

 

[Irondragon Forge ClayWorks]

I am wondering if Satanite would work better for the burner block with no aggregate in it.

[Buzzkill]

When I get around to it I'm going to try a casting with Satanite and small bamboo skewers.  My plan is do things kind of backwards though.  I intend to fill the mold with Satanite then use vibration to sink the skewers (embedded in a wooden block) from above through the Satanite and into a temporary foam insulation bottom.  Assuming that works then I'll flip the mold, remove the foam and set the plenum.   I've been busier than normal due to the pandemic, so I'm not sure when I'll get a chance to try this though.

[Frosty]

Aggregate does a number of things besides making concrete stronger and Kastolite is a concrete cemented together with a refractory cement NOT Portland cement. Anyway, the other main things aggregate provides in refractory is porosity so moisture can escape with out causing spalling. The other is allowing some movement in the block so it can expand and contract during thermal cycles without cracking.

I have sifted the more coarse aggregate from Kastolite for the flame face of NARB 2 replacing it with Zircopax and poured it in 2 lifts. Narb 2 is the one with a couple small cracks in the flame face. 

I have no idea how Satanite without aggregate would behave. I've never used the product so I can't say much of anything.

Oooh Buzz! I'll be watching for results, it sounds plausible.

Frosty The Lucky.

[JHCC]

Removed the rest of the mold from the ribbon block and fired things up.

 

Mod note: at the author's request, the longer post that originally appeared here has been moved to the thread describing this build in detail.

 

[Frosty]

The skewers wouldn't come out of the wood because they swelled absorbing moisture from the Kastolite. . . Maybe?

Looking pretty good John, a little rich maybe but it might be the calcite scavanging oxy from the fire so it might clean up after a while.

Frosty The Lucky.

[JHCC]

I think it’s more a matter of the beeswax layer acting as a glue until heated, at which point it became a lubricant. It was startling how easy it was to push them in, once warmed. 

[JHCC]

HORRIBLE REALIZATION!!!

I was checking back over my earlier comments on this build and realized that while I had done all my calculations based on 185 three-mm holes, I had actually only made 75. No idea how that happened, and no wonder I'm getting so much liftoff. 

Well, I guess I have to figure out if it's possible to do a 185-hole block.

[jlpservicesinc]

I love the enthusiasm..   Only off by 110..   Giddy up..  Love it..   

I'm a big fan of building upon a previous curve. 

[Frosty]

I was wondering about the # of outlets but a mistakes answers that perfectly. So build yourself a 1/2" T and see how that works in this burner. WHILE you build another NARB. 

Frosty The Lucky.

[Buzzkill]

I second Frosty's suggestion, mainly because I plan to build one of these to use with a 1/2 inch delivery system and I want to know if that's the right number of holes.  Let us know if you do decide to try it out.

[JHCC]

Seriously considering it. I had been thinking of relining my first gasser by simply layering more Kastolite over the existing (busted-up) surface, so a 1/2" FTB might be just the thing for that smaller volume. Hmmmm....

[Frosty]

I made the suggestion because it's an easy thing to check, a bushing reducer and screw the smaller burner in. Easy Peasy eh? I THINK I recall you made a 1/2" T or am I thinking of someone else?

I'd be breaking out the failing refractory rather than overlaying it. Can't build a good anything on a bad foundation. I don't think I'd make it smaller, it already looks small for a 3/4" T but that may just be this burner making it look that way. 

I'd just try the new burner before changing the forge. ONE change at a time is pretty ingrained in me and you ARE trouble shooting even if the problem SEEMS obvious.

Frosty The Lucky.

[JHCC]

I've only made the one 3/4" T; you must be thinking of someone else.

I've run the new forge on the old burner block, just not with the refractory layer on the inside of the doors. It worked quite well. You are quite right that this last test had too many variables at once (different ribbon block, different doors), so the next step is to test the old ribbon block in the new forge and see how the doors perform with the refractory layer. I'm wondering if the too-small number of holes (in the new ribbon block) may be part of the backpressure problem.

I just did some more layout with Onshape and discovered that I should be able to fit about 190-200 skewers into a 2" x 6" plenum, spaced on 1/4" centers in a honeycomb pattern. I'll try that next (I've got some more ideas for how to set up the mold), and then I'll test that in both the old forge and the new.

[Frosty]

I hope thinking of someone else didn't hurt your feelings too much, John.  

I'll be watching for the next creation / modification and test.

Frosty The Lucky.

[JADF]

So I ran it with an .035 and .045 what are you seeing? I'm thinking the .045 needs more air but I'm no expert. Ran it for 30 minutes and the outside of the tank got to 950 F

If it can get a bare tank that hot am I safe to think it should get plenty hot once lined and a partial door on the front?

[the2ndcashboy]

So I've run into an interesting issue with my 3/4" T NARB. I built it to the original plans some time ago, and it works great. It will run from <1psi up to the 20psi max on my regulator. It does start to burn back after about an hour if I'm running at less than 10psi, but that doesn't really bother me enough to apply the fix. My issue is that it doesn't really respond to adjustments of the mig tip length. I was trying some forge welding for the first time and I was struggling with scaling. Part of the problem was me leaving the back of the forge open like an idiot, but I've kind of suspected all along that I'm a little on the oxidizing side of FAM. I started experimenting, and so far I've ranged from a standard .035 mig tip cut down to about half its original length, all the way up to a double length mig tip that protrudes down into the throat of the T a ways and the flame doesn't seem to change at all. Now, if I take that same burner and lay it in the forge without the ribbon outlet, I can get a wide range of flame colors (FAMs) by adjusting mig tip length. The only way I can get the flame to change on the ribbon is to block about 75% of the inlet area. Even completely blocking one side of the T makes no difference at all in flame color. I'm baffled.

[the2ndcashboy]

Hopefully these video links work. I need to relearn how to post multimedia to the interwebz. Videos are in order from shortest tip to longest.

https://drive.google.com/file/d/1Q0SGQ5LSS1cao6wt2BN406LUIdq51d27/view?usp=drivesdk

https://drive.google.com/file/d/1Q2G35cGZorZnYDv87s6zoy36YH0RzTSE/view?usp=drivesdk

https://drive.google.com/file/d/1Q4DeqM2dZKfy93QWpn8PT0ZSIt8cANKz/view?usp=drivesdk

 

[Frosty]

It's harder for me to evaluate a video than still pics. It looks like it's running rich from what I can see but I'm getting so I hardly trust videos at all. The flames are blowing well off the burner block. How many outlets do you have in the block?

Try closing the doors up and see if that helps. If it's still running lean try using a tip file and enlarging the mig tip a little bit.

If you need to choke it, it's not a big deal choke it.

I've noticed mig tip length has a lot less effect on NARBs, I don't know why either.  

 Frosty The Lucky.

[the2ndcashboy]

I built the burner using your original as a pattern, I don't recall the number of holes right offhand. There does appear to be some flame standoff, but I can crank it straight to 20psi on cold start without blowing it out, so it must not be too much of a problem (the forge is basically stone cold in the videos). I don't get much visible dragons breath unless it's running near max pressure. At 10psi there's basically none visible unless I turn out the lights at night, then there's 6" or so of blue flame visible.

 

If I choke it down enough to affect the flame color, the burner gets a lot quieter due to reduced airflow, leading me to believe its not going to put enough mixture into the forge to maintain welding temps. I might just be chasing my tail here anyway. The burner/forge combo work well enough to peg my type K thermocouple at only 10psi, so it's probably just my lack of experience that's messing with my forge welding. I was just trying to eliminate the FAM variable when I ran into the tuning oddity. I actually noticed it when I built another frosty T for my brother with a different type of fitting for the mig tip that moved it deeper into the T. When I ran the new burner in my forge to test it, I noticed the flame had a very slight greenish tint, which I'd never seen out of my NARB unless I choked it almost all the way down. I screwed that burner into my NARB and the flame looked exactly the same as it had with my original inducer. That's when I started digging deeper.

 

Oh well, since the burner doesn't seem to be adjustable, I'll work on the other variables instead.

Edited June 1, 2020 by the2ndcashboy
Added info

[Buzzkill]

If you're consistently running lean with a .035 tip then move up to the next size tip and see what happens.   Conversely you could decrease the mixing tube diameter.  If you're using a schedule 40 nipple for the mixing tube you could try a schedule 80 nipple and see what happens.

I have likewise noticed that the normal tip trimming for tuning NARBs doesn't seem to have as much effect.  I was having the opposite problem - running consistently rich.  I ended up moving up in mixing tube diameter to fix my problem.

[Frosty]

The flame doesn't look rich to you Buzz?

2cash: When you say you're struggling with scaling. Is it scaling up IN the forge or after you take it out? Hot steel always forms scale rapidly when exposed to ambient air. It doesn't matter how you heat steel, the hotter it is the faster it will oxidize, this is basic chemistry. A good example is dropping an alkaseltzer tablet in a glass of hot water and compare it to one dropped in cold water. Warmer=faster.

From what I can see of the burner it appears to be burning rich to me. (not enough air for a neutral flame) It MAY be a trick of camera and light but the flames are opaque light blue start to finish. The size of your forge and how wide open it is may be providing enough ambient air to finish combustion in the chamber but it's too hard to tell. 

The currents made by the flame isn't as strong in a ribbon so it's easily possible to be forming back eddies that are drawing ambient air into the chamber. It's similar to the way a single nozzle burner can blow the flame and heat straight out the openings on the floor. It's different in detail but it's similar in how currents can form standing patterns. 

Ron Reil ran into this when he was measuring combustion by the composition of the exhaust gasses. He discovered that even with the propane and air intakes metered and burning neutrally the atmosphere IN the chamber had oxidizing regions. Not having his science education and instrumentation I came to working conclusions right or not while he worked on the mystery. One of the few times we almost came to angry disagreement. 

So, stop trying to make the FAM richer, it looks too rich to me already. Try closing the forge openings up a little or a lot until it gets to welding heat. The first restriction I'd make is an IFB laying flat across the opening to act as a sill to redirect exhaust gasses and any flames flowing outwards on the floor vertically upwards. The exhaust moving vertically in the doorway will encounter the low pressure zones caused by the burner flames directed downwards and instead of pure ambient air being drawn in the exhaust spent on oxygen will be. This should slow scaling IN the forge IF that's what's happening.

 Frosty The Lucky.

[Buzzkill]

I didn't watch the videos.  I was taking his word that he was getting scale in the forge.

I'll certainly defer to your opinion when reading flames though. 

So, if it's a rich flame I'd try a smaller mig tip or a larger diameter mixing tube. 

However, I think I've noticed that the number/size of outlet holes plays a part in the balance of the FAM as well.  My opinion/observation is that you can only pull in so much air when the back pressure in the plenum reaches a certain point, but you can continue to increase the fuel percentage with higher fuel pressure since it can overcome the back pressure.  In other words I think you can end up with an increasingly fuel rich mixture as you turn up the pressure, but not get much extra heat because of this phenomenon.  My setup seems to have a sweet spot for maximum heat.   Turning up the pressure past that point basically just burns more fuel, but doesn't seem to produce a higher temperature in the forge.  Of course that may not extrapolate to anyone else's setup.

[JADF]

Fired it up for 45 minutes. Got to forging temp no problem but need to get the door on to make welding temps.

Thanks for all the input on this, overall I'm happy with how it turned out and man is it quiet! There's room to tweak and improve but I don't have to start from scratch!

Thinking I should recast the burner so it isn't recessed so far and maybe drop a few holes to leave some more room around the edges.  It backfired a couple of times and the bottom of the plenum got to the 300 deg range and the top of it was125 deg