Ribbon Burner with 336 - 1/8" holes

[D.Rotblatt]

I've posted in the NA ribbon burner section about my NA burner with 124 holes at 1/8" each.  This burner is awesome; it does not backfire at all at any pressure (even down to shutting off - the flame just stops drawing air and goes to pure propane), with the same burner I use as the injector it gets the forge 100 degrees hotter, the flames are so small I can point them down from the top and the gas is fully combusted well before it's near the metal, I can turn it down to barely running which is about 1460F - great for heat treating, or I can turn it up to evenly heating the forge to 2350 or more for forge welding.  

Now I don't like to forge weld in this forge unless I don't use flux (I often do fluxless welding), but sometimes I do use flux for wrought iron and such. So the other day I was doing some wrought iron, and was using my larger ribbon forge and it just wasn't getting to heat like my little one does without hogging up the propane.  It's a gun burner (has a blower) with standard crayon size holes.  I decided to upgrade it and make a larger burner that had 1/8" holes to see how it works.

The new burner about 11x x 3.5". That gave me room for 336 1/8" holes.  Here is the burner shell and the wood drilled to receive the 1/8" sprue wax for the holes.  I have a cnc mill, so that made drilling the holes easy, but I could have done it with the drill press...set up with the CNC is pretty time consuming.  Below the wood form is my little NA ribbon burner.  It has 124 holes.

Here I'm putting little 4" pieces of sprue was into the form.  The sprue wax is in the back in piles of 100.  Yes...it was a pain to stick them all in.  I bought 3 lbs of sprue was from Duoglas & Sturgess (which is at artstuff dot com) for about $30 including shipping.  Enough to make a number of these burners.

 

No pics of putting the refractory in...but here's the gist of it.  The form was first painted with Vaseline as a release from the refractory.  I'm using Mizzou refractory.  One of the problems I had with my NA burner was that the mizzou has chunks of aggregate (probably ceramic or firebrick) which don't really fit between the was sprues well.  I spent a long time swearing over that little guy.  And no...it doesn't nicely spread out when vibrated, the aggregate is caught by the sprue and it forms clumps that push the sprue apart.  The only way I found to get it in place was to put small amounts in an area and push them into place with a knife.  So this time I sifted the Mizzou through a screen and separated out the aggregate.  I started with a small amount (maybe a couple of cups) and made it over wet.  I poured this over the top of the sprue and tried to vibrate it down...it clumped and pushed the sprues apart.  <insert well chosen words here>  I futzed with it with a knife and finally got the sprues pretty well lined up.  Then I used a little aggregate and made small amounts at a time and added them about 1/2 teaspoon at a time.  This worked pretty well.  The key was to work in small amounts - about 1 cup or so.  I put a final layer of Mizzou without aggregate on the sprue area to build up and even out the top (which will be the inside) and vibrated it down (which worked well to create an smooth top, but the sprues prevented high points from vibrating down).  Then I used regular mixed mizzou but with extra water to fill in the sides around the sprue (there is about 1/2" gap) until it is up to the level of the wood.  Do not vibrate until the metal shell is pushed into the mizzou or the aggregate will lock together and you won't be able to push it down.  Tapping the side with a hammer helps as you are pushing it down.

I put a couple of C clamps on to hold it all together and I bagged it up and it's setting now.  I'll pull it apart in a couple of days and report on the burnout...with some pics!

DanR

 

[Chris C]

That's my next step, DanR.  Thanks for you post.  Well written.  Can't wait to get started on mine.

[D.Rotblatt]

Update: Poured the refractory Sunday, and waited until Wednesday to allow the refractory to harden and pulled off the form  (just couldn't wait longer ). Monday I had poured some water into the pipe and re-bagged the end of the pipe...stayed nice and wet until I pulled it open.  The wood form with the sprues in it was nearly impossible to take off, all the sprues held into their holes like they were melted in there.  Had to slip a thin steak knife between the refractory and the board to cut the sprues, but finally got it off.  Bagged it up again, and I'll pull it out today (Friday) and dry and burn it out while I modify the forge to accept it. 

It's set up for a forced air system, but I'm considering trying a 1.25 or 1.5" Venturi burner as an injector to see if that works.  I'll see how the forced air system works first.  I'm suspecting I'll be able to get more stable low flames with the fan, since at low pressures (under 1/2 pounds) my little 3/4" NA ribbon burner won't pull air and goes to full propane.  The forced air system wont have that problem if I can tune the fan that low (I have a gate and dampers on the fan), but we're talking so low pressures it may not have any practical difference.

Next post I should have it up and running!

DanR

[Chris C]

Not sure I completely understand, Dan.  Why did you pour water into the pipe................and how much did you pour?

[Anachronist58]

D.Rotblatt,

Have you found that there is a minimum allowable thickness for the burner block, as applies to inducing a modicum of laminar flow to the Fuel Air Mix, or to prevent backfiring (pre-ignition)?

I have some .030" thick perforated inconel sheet that I am considering........ will have to dig it up to get hole size and count........

Robert Taylor

[D.Rotblatt]

7 hours ago, Chris The Curious said:

Why did you pour water into the pipe................and how much did you pour?

Refractory is like cement.  It does not 'dry' it goes through a chemical reaction and hardens. If like portland cement, it forms crystals in a chemical reaction called hydration.  The water mix initially is important, too much or too little water and it will weaken the cement.  If too much in the mix, the particles are too far apart.  Too little and there's not enough for hydration to fully occur.  But my understanding, is that once set up, it is important to keep it wet so the hydration process continues and the refractory gets even harder.  I always learned to hose down a new cement slab several times a day for the first few days while setting.  Thus, I poured a quarter bottle of water in the intake pipe and turned the burner so it would keep the refractory wet.  I may be wrong and that is adding too much water, but I figured that it would just sit on top, the particles were already set in place and the reaction occuring.  Refractory also hardens when fired, so there area a couple of things going on.  

The burner is now sitting in my kiln at 190F drying out.  When it seems pretty dry, I'll turn it up to 300 an melt the wax out and then as soon as the forge is ready I'll put it in and fire...Should be sometime this week!

6 hours ago, Anachronist58 said:

Have you found that there is a minimum allowable thickness for the burner block

I have not experimented with thinner blocks so I can only hypothesize, so take these thoughts in that light.

First, a few people are playing with perferated ceramic tiles (one a casting filter and the other is for BBQ's I think).  Check the NA ribbon burner section or the ribbon burner section and see if you can find them.  Maybe 6 months ago? 

Info that might help: I did read that a flame will not pass a screen with holes of a certain diameter or smaller (depending on the type of gas). For propane the size is about 1/8" or a little smaller.  What happens is the heat of the flame cannot support itself in so small an area - the heat loss extinguishes the flame.    Back in the 1800's they made a special lantern for use in coal mines that had explosive gasses.  It used a screen to surround the flame with small mesh.  This prevented the flame from passing through the screen.  Google that and see what you can find.  My feeling is that the inconel sheet will work, but may backfire when it gets hot - the metal being up close to ignition temperatures.  You'd have to experiment to see how it works.  Possibly with smaller holes then the 1/8".  Love to hear the results!

DanR

[Chris C]

Thanks, Dan.  I do that when I pour concrete...........just didn't think about doing it with refractory materials.

[G-son]

These cooking burners use very thin metal and small holes, seems to work there. But I'd also worry about backfiring when the metal gets hot as it does in a forge. Might need a material that insulates better. or perhaps cooling the metal in one way or another, but removing heat from a forge seems counter productive.


 

[D.Rotblatt]

First firing of the new burner. In prep, I put it in my kiln for a few hours at 190F to dry it, upped it to 250 to melt out the wax, then 350 to burn off the wax that had soaked into the refractory.  Worked on the new forge it's to be installed in in the meantime.  I was going to rebuild my other forge, but had found a nice piece of 10" stainless stove pipe on the side of the road and figured it was as much work to make a new one as it was to rebuild the old one.  I figured I'll just use the door from my old one since it is removable.  I also made it a few inches longer (14" interior length vs 12") and it will have a bit more insulation (being a little bigger diameter, and a smaller diameter interior planed).

The flame was pretty good, didn't hold well to the block even at moderate pressures when lean, but ok when rich (meh when neutral). This will work totally fine in the forge though.  I was using my little Dayton blower which is not very strong and there seemed to be very little back pressure.  Larger flames (more pressure) would start lifting a lot from the block, especially around the edges and the bottom and when lean.  The individual burners do keep their neighbors lit, so the ones around the edges are not surrounded and lift off.  Also the flame goes up, so the bottom ones wouldn't get lit well.  I think it will work much better in a vertical position and inside a forge.

This pic is with the damper around 3/4 closed.

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This is with the damper completely closed, and a gate I added almost completely closed.  Closeup in the next shot.  The flames are about 1/8" long.  I'll be interested to see what temperature this will make the forge. My goal is a burner/forge that can be used for HT at 1450-1550, or welding up to 2400F.  At this low pressure the NARB would not pull air and go completely to propane, but since this is a fan blown one there is not problem with it turned down.  

Closeup with it turned down as low as I can.  I'd be excited if I wasn't so beat from building the forge body all day (almost ready to put in the inswool, bricks, etc.)

_______________________________________________

13 hours ago, G-son said:

But I'd also worry about backfiring when the metal gets hot as it does in a forge.

Those propane cook stoves get hot...I mean the metal burner gets red hot when it's on and they do not backfire.  I'd make a test one and give it a try, at worst it will backfire and you answered the question.  Use the hole size on that propane stove as a guideline, since it runs on propane.  A crapload of little tiny holes!

DanR

[Frosty]

On 9/27/2019 at 5:39 PM, Chris The Curious said:

Thanks, Dan.  I do that when I pour concrete...........just didn't think about doing it with refractory materials.

I don't think it does with all refractories. I wish the Kastolite people would include instructions for: prep, mixing, set and cure procedures but you have to really hunt online and the info if for 55lb. sacks. Once set portland cement materials and Kastolite can't be un-set with water, 100% humidity, heck submerge it even provides water for full hydration. The Kastolite information said in more than one place their product behaved so  much like Portland cement you should use the same processes for full strength and temp rating. 

Don't ask me why, I have a very basic knowledge, not to be confused with "understanding" of "portland cement" concretes from testing them in the material's lab way back when. We: measured, mixed, poured, stripped, cured, capped and broke 3 cylinders for every project requiring certification which was anything with State or Fed money involved, the City has it's own lab and we cross checked results on special projects. 

Frosty The Lucky.

[Chris C]

Since I've not mixed KOL30 yet, I've still many questions about the process, Frosty.  Everyone mentions how it is pretty darned "lumpy" because of the aggregate.   Can that be crushed before mixing so it flows better?

[Frosty]

I haven't had any luck crushing the aggregate but I haven't opened that can of whoop rock, I just sifted it through a kitchen wire colander. I don't want to sift through a window screen, I'd be concerned how much that would effect the structural integrity of the burner block.

Aggregate has two main jobs in refractory: First is to provide enough flexibility the set refractory can expand and contract during thermal cycles it won't crumble. Originally I thought the main purpose was the same as Portland cement concrete and provide compressive strength but I was wrong. It's second purpose is directly related to it's first and that is to prevent the set refractory from being steam tight. It's there to provide enough porosity in the set refractory steam can escape and not cause spalling or worse. 

I BELIEVE (with all due caveats) I got away with sifting larger aggregate from the mix because the outlet pathways (crayon holes) are so close together steam doesn't have far to travel for pressure relief. The largest thickness on my blocks is under 1/4" and so far so good. 

Replacing sifted aggregate with bubble makes up for porosity as it's not possible to stack spheres without gaps so steam can escape. Using Zircopax on the other hand might fill too many voids and cause problems but fortunately it doesn't require much binder to sinter to itself so it's worth a couple test coupons. I think zircopax, refractory grout is a good bet but it IS a bet.

Frosty The Lucky.

[D.Rotblatt]

49 minutes ago, Frosty said:

Aggregate has two main jobs in refractory

Chris, please note this, as I was under the impression (no assumption) that the aggregate is for strength.  Though it may not be for strength, it is still an important ingredient.

Thank you Frosty for giving some input on this!  I did sift out the aggregate in this FARB, but added it back in in smaller amounts.  I crushed some (that stuff is hard!  had to use a hammer with a 1/2" steel plate). I added it back in so small aggregate was on the face where it would be easier to get between the sprues and then kept adding larger and larger as I got up higher and it was easier to push between.  Worked in about 1 cup batches of refractory so it wouldn't set up.  I did have some aggregate left over, so I used a smaller amount then originally was in it.

I was afraid not to use any aggregate though I did on one of two thin layers, since I figured the Mizzou would not be strong enough.  It was totally an instinctive thing, since i did no tests...hmmm...tests...tests?.....we don't need no tests, I don't have to do no stinkin' tests! 

Anyway, I've got a burner with mixed amounts of aggregate of different sizes.  We'll see how it holds up, or if it explodes   So far so good.

DanR

[Frosty]

Yeah, aggregate is there for strength but that's not it's main job. Well, sort of it has to allow steam to escape and maintain enough strength to keep it from crumbling. My actual knowledge base where cements and concretes are concerned is very basic for a dust monkey lab tech. Were it to come through the materials lab, testing Kastolite wouldn't bat an eye, the concrete guy would read the specs and we'd put it to his test designs. 

If one of your burners explodes  don't do that again! 

Frosty The Lucky.

[Chris C]

1 hour ago, D.Rotblatt said:

Chris, please note this, as I was under the impression (no assumption) that the aggregate is for strength.  Though it may not be for strength, it is still an important ingredient.

Got it.

 

1 hour ago, Frosty said:

If one of your burners explodes  don't do that again! 

You guys are startin' ta skeer me! 

[D.Rotblatt]

4 hours ago, Chris The Curious said:

You guys are startin' ta skeer me! 

They don't usually explode....they generally just pop and a piece flys off.  All safely enclosed in your forge....mostly 

[Chris C]

Ain't skeert.....just joshin'.

Chris

[Old Crew]

Chris

I am skeert of casting a burner so I have been playing with drilling one.

163    1/8 inch holes in a 2800 brick cut to 4-1/2 x 8   The burner is 1/2 larger than the brick I put the brick into the burner and packed kaowool around the edges to test. When I am done testing the brick will be locked in with castable.

Some gas leaked past the kaowool and bang pushed the brick out of the base on one side.

As for the Eyore reference I wasn't trying to be offensive so If that is how it came across   sorry

David

PS   thats is the burner running as low as the regulator goes   2 psi?

[Chris C]

No offense taken.  I just didn't understand the humor because I didn't know what the Donkey's character was all about.

Chris

[Irondragon Forge ClayWorks]

I like your new avatar picture Chris. BTW, I just copied the Eyore description from Wiki.

[Chris C]

Thanks.

Chris

[Frosty]

3 hours ago, Chris The Curious said:

Ain't skeert.....just joshin'.

DRATS! We're not doing it right Dan. We're supposed to "keep up the skeer" aren't we? 

Your burner looks to be burning well Old Crew. Have you fired the forge with it yet?

Beautiful anvil stand Chris She'll look great with some scorch marks.

Frosty The Lucky.

[Chris C]

1 hour ago, Frosty said:

Beautiful anvil stand Chris She'll look great with some scorch marks.

  Thanks, Frosty.

 

Chris

[D.Rotblatt]

13 hours ago, Frosty said:

DRATS! We're not doing it right Dan. We're supposed to "keep up the skeer" aren't we? 

Sigh...we do our best to raise them right, but it's as if they have a mind of their own 

[D.Rotblatt]

First Burn was successful with some caveats.   Interesting results and pretty positive given that this is a first experiment with a 1/8" hole FARB.

BEFORE STARTING:

1) I soldered the jets closed and redrilled them to two #60 (or .040) holes.  That way, the gas used will be equivalent to 2 Reil burners at any given pressure and I have some point of comparison.  i.e. this should compare in gas use to a 2 Reil burner forge at any given pressure which I am familiar with.

2) The new forge is about 350 cu inches.  2" of ceramic fiber coated with the eggshell zircon and an IFB covered with a 1/2" mizzou shelf on the bottom.

3) The interior of the forge is 14" long and the inside is a 'D' shape. The burner is 11" long, 4" wide.

THE GOOD:

After some time futzing (explained in next section), I was able to get it running quite well.  

-At 10 lbs it was 2200F.  The temp was still slowly rising, but it was getting late towards dinner plans.

-At 15 lbs it was 2375 and still slowly creeping up.  Easy welding heat for carbon steels.

-Quiet when running full on.

THE BAD:

-The sucker sings in two pitches...and really LOUD!  I now know what is causing the 'singing' - it is backfiring.  The plenum was getting warm after it was doing this for awhile, but not too warm to touch.  Closing the fan damper, or giving it more propane richens up the mixture and it stops backfiring/singing.  Like the NARB, this stops once the face of the burner gets hot enough to ignite the propane before it goes back burns.  Unfortunately, the face of the burner seems to stay cool a long time, so this process is time consuming.

-Poor low temperature.  Couldn't get it down below 1700F, though I could get the propane pressure down to 3 lbs or so.

AND THE UGLY:

-Hard to get up to heat.  If run at low pressures with a cool burner face, it needs to be pretty rich so it will stall at 1500-1800F.  After some futzing, I worked out of procedure for getting it up to heat.  I finally figured out it needed more pressure to keep it from backfiring so I started it at 15lbs propane pressure, damper 1/2 open, and gate 3/4 closed until it just stops singing (yes I have a damper and gate on it while I figure it out).  As it heats up I open the gate a little at a time but keeping it from singing.  When it reaches about 1900F it seems to stop singing, then I can open the gate all the way and back off the propane til I get a neutral flame which is around 8-9 lbs.  After that, I can adjust as I want as long as the face of the burner stays hot it seems to be good.  I haven't run it for a long period yet, so we'll have to see how it responds to that.

POSSIBLE FIXES:

-It seems that one problem is lack of pressure allowing the backfiring. It runs with the damper 100% closed.  I just may have too many holes.  I did this on purpose because it's so easy to plug holes, and so hard to add more.  So Fix Experiment #1 is to block a couple rows of holes to see if this increases pressure and decreases backfiring.  Little tiny wads of ceramic fiber....

-The face needs to heat up to prevent backfiring.  This is the case with the NARB as well, though it is so small of a forge that it heats quickly.  Fix Experiment #2 is to lower the burner down into the forge further so it will heat up more.  I can drop it down 3/4 of an inch without any modifications, and with a small mod (moving 3 tabs), I can go deeper.

DanR

Pics:

Here you can see the whole set-up (except the little Dayton blower down on the bottom).  Running at 10lbs propane. 

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Running at 2200F at 10lbs propane.

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Closeup of the inside at 2375F.  Really even heat, don't know if you can see it here, but there are no hot spots.  For the gas of 2 real burners, the entire forge is an even 2375F from front to back.  A two burner forge would have two hot spots, and cooler areas.  This is the most even heat I've ever seen in a forge.