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Naturally Aspirated Ribbon Burner. Photo heavy.


Frosty

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On 12/30/2018 at 10:29 AM, Judson Yaggy said:

3/4" with an AMAL commercial injector.

Very nice build indeed. I wondered about the fire brick being used that way also.  Just built a 1/2" side arm burner, this is going to be an experimental build in the quest for efficiency. A small 4x4x6ish chamber with an entire side being a burner face consisting of many much smaller outlets. Material being maybe a drilled ceramic plate or heavy screen of some sort. The emphasis is on the smaller screen-like outlets.This is a completely for fun and experimental build! thanks for ideas and input!

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I ordered those Ceramic bbq blocks. I will fire test them in the forge and see how well they hold up before fabricating to them. It would be nice to have pre made flame faces. Im sure I will need to stack to avoid super heating and ignition in the plenum. But then again, I have no idea what I'm doing. 

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I used a grinder to cut groves on the inside of the steel plenum, carved shallow half dovetails in the fire brick, and glued the brick into the plenum with furnace cement.  The cement locked into the groves and dovetails and once cured seemed quite secure.  Time will tell if I get expansion differential problems, but 10 hours of burn time so far and no problems.  

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Put'em in the forge and brought up to yellow during a  short session (about an hour). Took em out after cooling and still as hard as they were before. Stuffed a 1/2" sidearm with a plenum from a bag balm tin, glued all the seams with kitty litter and experiment test fired. It lit immediately and turned up to about 5 psi before backfiring. A little adjusting and got it roaring before the tin warped and failed. But results were already in! It works! Now for a design. I can't think of any way to secure the pre Made faces to anything other than making a mold and surrounding with kasto. Lol, might as well just cast an actual ribbon. But I have these and paid for them. Creative tank needs replenishing.

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  • 2 weeks later...

Ditching the pre made faces. Casting instead. Go figure

Just wondering if the 1/2" burner will work with this 1 1/4" plenum. I plan on using stir straws for nozzle holes. I know it's a thing of ratios. 

How much space in the plenum is needed? 

I will use two 1" wool split with a layer of perlite rigidized in place and a thin layer of kasto 30 for the dome. A layer of wool covered by mostly perlite glued together with a little kasto for the floor.

Any tips?

 

 

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Sorry about the slow reply, my memory sucks.

I think that's plenty of plenum but I've never built one that size. The thing is to have enough volume for the pressure to equalize over all the burner outlets.

17 hours ago, 671jungle said:

I will use two 1" wool split with a layer of perlite rigidized in place and a thin layer of kasto 30 for the dome. A layer of wool covered by mostly perlite glued together with a little kasto for the floor.

I don't understand what you're doing here. Is the perlite between the wool layers, between the wool and kastolite, or what? Why are you using perlite at all? It melts at just under 2,000f so if I understand how you want to make the floor it will fail pretty quickly. 

In part I can't tell in what order you're building the liner. From the shell in: wool, 2 ea. 1" 1 lb. Then 1/2" Kastolite 30 or equivalent. Lastly, Kiln wash about the thickness of two coats latex paint.

I can't think of anywhere to use perlite. If you put it directly behind the hard refractory, Kastolite, it'll melt. The outside of the Kastolite layer is going to get almost as hot as the interior of the forge. Perlite doesn't stand a chance. I know Mike talks about where a person could use it but doesn't recommend it. 

Jerry

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6 minutes ago, Frosty said:

I can't think of anywhere to use perlite.

I use it for the bottom layer on the floor of curved shells.  That allows me to create a more or less flat surface to lay the fiber blanket on.  The same thing could be accomplished with scrap pieces of blanket, but perlite is dirt cheap and will conform to any shape to give that flat base layer.  It's far enough removed from the forge chamber to avoid any melting issues that way.

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All good Frosty! We need room for other lifestuff!

Keep perlite away from 1st layers. Only as outside layer. Understood. 

I was going to fuse the perlite between the 2 layers of wool with rigidizer for the dome. Maybe more trouble than it's worth. But I will stray from using it in the floor. 

So from what I understand.

Pressure from jet entrains air into mixer tube increasing velocity while lowering pressure completing FAM.

Reaching the plenum, velocity slows and pressure increases in the plenum. 

FAM velocity increases again while in the nozzlettes creating All the little high output flames?

 

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Agreed, between the shell and blanket works well for a flat floor. A cake pan for the bottom of the shell is flat to start. Good good.

I wasn't very clear, I meant I couldn't think of anywhere for perlite in this build. 2" of blanket and 1/2" hard liner and makes a nice working volume and plenty of insulation. Adding another layer of insulation won't help performance appreciably but will reduce working space.

If the shell under the floor is getting too HOT, indicating significant heat loss. More insulation under the floor might be called for and simply setting the forge on a bed of perlite in a larger pan would do it nicely. 

I've never tried measuring the temp between inner and outer layers of Kaowool so I don't know if you could replace the outer layer with perlite. I'd be surprised if it wouldn't work, I don't think temps exceed 2,000 f. after the first inch. My first forge was 3/4" Pyramid super and 1" of Kaowool running under a 1" T. It'd easily melt your work if you didn't keep an eye on it and the shell didn't get hot enough to make a melted cheese sandwich, let alone a grilled cheese. The shell got WAY too hot to touch though, not quite boil spit hot.

Using cemented perlite for the second layer of insulation out from the flame face can be done but the real question being. Is it worth the extra work?

1 hour ago, 671jungle said:

I was going to fuse the perlite between the 2 layers of wool with rigidizer for the dome. Maybe more trouble than it's worth. But I will stray from using it in the floor. 

Ah, you're back. Yes I think so.

1 hour ago, 671jungle said:

Reaching the plenum, velocity slows and pressure increases in the plenum. 

FAM velocity increases again while in the nozzlettes creating All the little high output flames?

I have no idea if the FAM slows down in the plenum or if it should. I just need it to equalize over the outlets so they're all evenly fed. My only concern is the velocity through the outlets is higher than the FAM's rate of propagation, (flame front) or it'll burn back into the plenum. Then it's game over, you have a flammable FAM all the way up the inducer.

THAT'S the critical balance, enough outlets to maintain a consistently lower back pressure so the inducer works while maintaining a high enough outlet velocity it won't burn back. 

I did all my testing with 2" x 4" burner blocks. Drilled holes screwed it to the plenum and lit it up to see what happened. They only needed to run for 20 seconds max to see if they'd work through useful psi ranges.

If you're curious why I ran my first forge with a 1" T, I didn't know what I was doing and that was my first successful NA burner. I made the list of beginner overkill mistakes. Heavy pipe shell and 2x as much burner as it needed. It turned down to a working temps though and worked just fine till I got the T's figured out. Convinced more than one person you could indeed weld in a NA forge and it didn't scale steel up in the forge. It burns way too rich to use indoors, it's actually reduce scale to clean steel it's so rich. AND melt it if you didn't pay attention. I don't use it, haven't for years. It's still there though.

Frosty The Lucky.

 

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On 12/12/2018 at 9:39 PM, aonar said:

Frosty - it was more a thought experiment.  and i was thinking if you had a blank area in the middle to give turbulence a chance to settle from the mixing of the two streams it might not conflict too greatly.  I am not doing any forging yet.  just reading and had a weird idea is all.

I was wondering the same thing. Especially with a smaller plenum. I think the baffle in the Emmerling design serves to deflect the FAM from concentrating on the immediate nozzlettes and helps slow velocity.

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13 hours ago, 671jungle said:

I was wondering the same thing. Especially with a smaller plenum. I think the baffle in the Emmerling design serves to deflect the FAM from concentrating on the immediate nozzlettes and helps slow velocity.

If you read more on that design you see folks looking for blowers that produce high static pressure and videos of the forges show dragon's breath sometimes 3-4 FEET long! 

The one time I used a baffle in the plenum I put it half way across rather than almost blocking the inlet like John specs. The idea is ONLY to evenly distribute pressure so you don't end up with giant flames under the FAM inlet compared to shorties at the ends. 

The test plenum I made with the inlet aimed at the outlets showed uneven flame lengths even with a baffle. Placing the inlet at 90* to the outlets evened the flames out enough I don't care to do more. The center flames are only slightly longer than the far ends. Good enough for me.

You are focusing on velocity where it doesn't matter, the ONLY thing the plenum does is distribute FAM evenly across all the outlets. It's ONLY in the inlets FAM velocity matters and that's to prevent burn back. Everything else, EVERYTHING about the build is to prevent too much back pressure for the inducer to work against effectively.

Frosty The Lucky.

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1st test block fired with 1/2" Mikey injector.

Couldn't get it to roar consistently. (Induction issue?) Didn't backfire and was blowing out at higher psi ranges(5-10).

1 1/4" x 9"ish plenum

3x7 rows of coffee straw O.D. holes.

One more row might do it without too much back pressure from the forge?

I hope I'm understanding the direction I'm going about back pressure.

2nd shows those demented candles Frosty mentioned at the beginning of creation.

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I used 14 holes of 9/32" diameter for my NARB which uses a 1/2" Frosty T burner.   Unfortunately I have no idea how to calculate the number of holes of a particular diameter needed, so my general approach is to start with too many holes and then start plugging them until I get the results I want.   If you're blowing the flame out at 5 to 10 psi my guess is another row could get you pretty close to where you want to be.  I'm definitely interested in seeing where you end up because I was already thinking about casting the next one with more holes of smaller diameter.

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It's not roaring, multiple outlet burners don't. Yours is running rich, the second pic is very rich. It needs more psi to induce properly and needs more outlets. The disparity in flame length might indicate it needs a difuser.

More holes, more psi or open the choke.

My wood block 0* inlet didn't have even flames either and led me to try the 90* inlet. The difuser I put in the 0* crossed the plenum about half way from the inlet. It was about 2"-2.5" "long".  It evened everything out nicely though not completely. 

Buzz: I started with my best guess # and drilled more holes till it was right. Wood doesn't last long but you only need to see it burning a few seconds once you know the look.  

Frosty The Lucky.

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Thanks Frosty. You and Mikes knowledge and experience has been critical in this project of mine and many others.  Much appreciated.

Used the same block but drilled seven more holes. One between each row of three. Seems to run a bit better. Still some lift when I try to tune the 1/2" Mikey. The lift is happening when the jet is around 1/4" down the throat. Stabilizes around an 1" down the throat but is very candle-like and rich.

More holes? Or make the single holes slightly larger?

Perhaps lengthen the choke slots (2"x3/8")? I remember reading anywhere past 2" length is waste.

Anyway, this is fun stuff!

 

 

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Thanks Frosty. You and Mikes knowledge and experience has been critical in this project of mine and many others.  Much appreciated.

Used the same block but drilled seven more holes. One between each row of three. Seems to run a bit better. Still some lift when I try to tune the 1/2" Mikey. The lift is happening when the jet is around 1/4" down the throat. Stabilizes around an 1" down the throat but is very candle-like and rich.

More holes? Or make the single holes slightly larger?

Perhaps lengthen the choke slots (2"x3/8")? I remember reading anywhere past 2" length is waste.

Anyway, this is fun stuff!

Also I am using a .025 jet. Smaller May be what is needed?

 

 

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