WIP Forced Air Dual Ribbon Burner.

[thematrixiam]

Hey guys.

I was wondering If I could get some help with the parts and pieces for my design...

I'm going to frame out my box with 11 gauge cold rolled, just angle and screws to hold the edges. Size will be horizontal 19", Virtical 11", Front to back 13". The size of the forge will shrink when I add wool. Was thinking 1" around the edge, plus anything extra that I add when sealing the kaowool. I could make the kaowool 2" thick if you guys think it is appropriate.

I was thinking of adding the ribbon burners on the top... I have seen some side/bottom designs for round tanks, but mine is not round. 

The ribbon burner frames are 6x3 with 2" BIP going in. I have two of them.

 

 

Going to try to add in a static mixer as well. There is another thread I made asking about a DIY static mixer :

Do you think 2 ribbons is over kill for this size of forge? My aim is to have a wider forge for making larger items such as battle axes etc. 


I already have a propane gauge with regulator up to 30 psi. It's connected to a hose with a quick connect/shutoff. I am using it with my other forge.

What sort of connections will I need? Getting the gas in? To the 2"?
Blower to the 2"?

Can I use cheaper material than BIP, or will it melt?

What about a blower? What are good? I live in Canada, Alberta... Near Edmonton.

Any other shut offs for regulating flow of mix? Flow of air? 


Thanks guys.
 

[Frosty]

That's more of a list of stuff you think will work than a plan. What is BIP? 

How many cu/in are you looking to heat? 

What size doors? 

And so on. I'm not doing your math, so I don't have any idea how much fuel it'll require. No telling without knowing how much volume and hot you want it to get.

I'd love to help but we need you to come up with a better plan and some important details.

Frosty The Lucky.

[thematrixiam]

Hey. BIP means black iron pipe.

size = between 1,365 cu in or 1,989 cu in. Doors either 17x9 or 15x7.

Not sure what you mean by better plan.

This is my first forge. I made every inch of that. I also coated it with Kast-o-lite 30 plus. I made it as part of my 4th year project... got some great marks. After some mark up dates and such, and some paper work, I will be a journeyman in both Gas fitting Class B and Sheet Metal Worker.

[thematrixiam]

20 hours ago, Frosty said:

 

I'd love to help but we need you to come up with a better plan and some important details.

Frosty The Lucky.

Thanks for your offer to help Frosty.

What important details do you want?

Size? See above?

Gas? Propane.

Insulation?
Kaowool 3000F

Wool Sealant?
Kast-o-lite 30 Plus

Shape?
Rectangle

Power?
120v

Desired method of mixing?
Static Mixer

Desired connection to propane?
Quick connect.

--------------------------------------------------------------

I do have some nice handy code books and reference material that I can use. As a gas fitter it's part of the job.

I am looking for constructive help to discuss:
1: types/sizes of blowers used based on size of forge (re: "size = between 1,365 cu in or 1,989 cu in. Doors either 17x9 or 15x7.")
2: number of ribbon burners of size 5x2 (see pictures above)
3: recommended orifice size
4: recommended method of connecting the separate feeds(propane and atmospheric air) to the system.


 

[Frosty]

The picture of the static mixers you were referring to didn't download to my machine for some reason. That's happening more often now, I have to talk to my ISP about that and another issue, I'm getting repeat downloads of Email. 

I see what you mean by static mixing tube, makes sense. I don't usually work with gun burners as in make or trouble shoot them. I recommend introducing the propane as close to the blower as practical then running the pipe around a couple 90* bends to induce turbulence and mix the fuel air. 

I think I have a clear enough image of what you're doing for discussions sake. Thank you for putting up with my knee jerk reaction, I'm trying to get a handle on it. 

The method I'd really prefer but has been pointed out as being too dangerous to use without a sealed motor blower is to introduce the propane into the blower fan with the air. That would be a non-static mixer, yes? I concede that's not a practical idea without spending a lot more money than one should on a home build. 

My other idea ran to mimicking the mixer in my All States, oxy propane torch handle. They have a twisted strip in the torches after the adjustment valves that swirls the oxy prop to mix it thoroughly before the tip. My thought was to place a twisted strip of perforated sheet right after the propane jet. 

My other thought will only work in a system with a high flow velocity but should mix as thoroughly as possible and that is a cavitation zone. If the propane is introduced to a near vacuum that violently collapses shortly afterwards the tightly bound propane mist will be shattered into an actual gas and mix. While propane IS a gas it behaves more like a mist of droplets. No I can't explain it I have accepted the word of people who work with propane on a daily basis and Lyle the gentleman who invented the All States oxy propane torch. 

The cavitation mixer is a method of atomizing fuel oil at least in our boiler. It is done by passing the very high psi injector stream over a knife edge or a bullet shaped air foil. (I do NOT recall which but we talked about both) and into a spinning fan. The cavitator creates a near vacuum which collapses violently shattering the oil mist atomizing it and the spinning fan creates a strong vortex that prevents it impinging directly on the fire brick. 

When I asked him about propane boilers he told me they don't have the impeller to induce a vortex but there is a cavitator, just not as aggressive as in an oil furnace. In both cases they need a fast flow.

 

Your forge looks like a blast from the past, is it based on the Sandia recuperative forge?  It's been years since I've heard about one let alone seen a new one. Cool.

Home built burners have advanced a lot since the Sandia boys came up with their burner. A little tuning and it's nothing special to get a forge to welding heat. In the past when "everybody" knew you couldn't weld in a propane forge it was mostly a matter of not knowing HOW to weld in a propane forge. Most guys were running oxidizing flames to get heat but that scales up the steel and poisons welds. Forges were typically steel pipes with an inch of Mizzou. 

More modern forges have at least an inch of insulating refractory and a layer of hard inner liner to protect it. A properly tuned burner will easily reach welding temps with a little help like a forge volume within it's capacity. The Sandia recuperative forge was a method to overcome the "deficiencies" of propane burners invented by rocket scientists. Literally though maybe all of them weren't "Rocket" scientists, I think maybe a couple nuclear physicists were involved. I can't recall his name but one of them was a blacksmith.

Anyway, with a better understanding of forge builds and burner tuning the recuperative component of the Sandia forge isn't necessary. IN my limited experience with multi outlet burners I've found they get too hot and begin burning back into the plenum and as seen in more than one instance currently being discussed on the forum they blow out. Either way a ribbon burner burning in the plenum is in failure mode.

My problem has been keeping the burner block cool enough the rate of propagation is lower than the flow velocity, the hotter the flow the  lower it's rate of propagation. When I was brainstorming home made ribbon burners after I discovered I had a pair of working burners, I was going to build a steel shroud over the plenum and mixing tube from the T to preheat the mix. Boy would that have been a mistake, I can't keep the flow cool enough unless I run it at high pressure. High pressure for my set up is around 5-7 psi. but the burner is stable stop to stop on my 0-20 psi regulator. It's perfectly happy at either end but below 3 psi it starts burning back within an hour or so, at 7+ psi I can run it all day, at 20 psi. it melts your work if you're not watching.

 

1,300 - almost 2,000 cu/in is a HUGE forge. Are you starting a commercial forging operation? If so you might want to consider induction forges, they're fast and energy efficient, they use hardly any power unless there's something in the coil.

Almost all of have build a WAY too large forge starting out, I still tend to make them larger than I actually need. I have a 4 burner variable volume forge as my shop forge and almost never use two burners, one 9" x 9" x 4.5" chamber handles almost everything I do. Occasionally I open another section to forge long stock say incising square stock to make rope twists. Then its 4.5" x 9" x 18". The couple time I've had all 4 burners running other than testing it was when I had a hammer in going and had 2-3 stations operating. It's still set up but I use my ribbon burner almost exclusively, the variable volume forge needs to be dismantled and recycled for other things.

Anyway, I think you're building WAY too large, just like a lot of us here, and that's a lot of work if you don't actually need that much. Seriously heating that much volume will burn 3 or 4 times the fuel my 2 burner ribbon forge does and I don't turn it up to welding temp unless I'm welding. I use about 1/2 the space in it now. 

Off the top of my head I think: #1 The recuperative air preheat system will cause it to burn back into the plenum unless you have the blower really cranked up. 

#2 It's way larger than you'll need unless you're setting up a commercial operation in which case I recommend you look into induction forges. Propane savings should pay for the induction heaters within a year. That's an eyeball quesstimate based on how fast a propane, 4 burner gun burner forge uses. I have a Johnson Gas Appliance trench forge out behind the shop. I used one a few times many years ago and that one would go through propane like a dragster goes through nitro methane.

I've probably over rambled already. 

Frosty The Lucky.

[thematrixiam]

8 hours ago, Frosty said:

Anyway, with a better understanding of forge builds and burner tuning the recuperative component of the Sandia forge isn't necessary. IN my limited experience with multi outlet burners I've found they get too hot and begin burning back into the plenum and as seen in more than one instance currently being discussed on the forum they blow out. Either way a ribbon burner burning in the plenum is in failure mode.

Opps. I think we're on different pages. That is my first forge. I am making a second forge that uses ribbon burners.

 

8 hours ago, Frosty said:

High pressure for my set up is around 5-7 psi. but the burner is stable stop to stop on my 0-20 psi regulator. It's perfectly happy at either end but below 3 psi it starts burning back within an hour or so, at 7+ psi I can run it all day, at 20 psi. it melts your work if you're not watching.

Keep in mind, and I am sure you know this, but PSI is not the same as BTU or Velocity. PSI is pressure. If your orifice is small, like say #70 drill bit size, such as in my recuperative forge, then your psi will be required to be higher to get the same amount of BTU.

If you have a look at "Orifice BTU PSI propane charts" you can find out the theoretical input of gas using that orifice. 

But theory isn't always correct. You'd need to install a meter to register what was coming out. And then do a Delta T calculation to figure out how much is burnt. 

 

 

8 hours ago, Frosty said:

Off the top of my head I think: #1 The recuperative air preheat system will cause it to burn back into the plenum unless you have the blower really cranked up. 

Re: I am not modifying my recoup forge. I am making a new one.

 

 

8 hours ago, Frosty said:

#2 It's way larger than you'll need unless you're setting up a commercial operation in which case I recommend you look into induction forges. Propane savings should pay for the induction heaters within a year. That's an eyeball quesstimate based on how fast a propane, 4 burner gun burner forge uses. I have a Johnson Gas Appliance trench forge out behind the shop. I used one a few times many years ago and that one would go through propane like a dragster goes through nitro methane.

It's more so I can fit in larger items. Such as a battle axe with a 12" wide face. If I end up selling items then I could see myself doing more. But as it stands it's for personal use only.

As I have a smaller forge I want a larger one where I can do larger items it.

I was thinking of creating blocks to fill in the space and cut off the volume as required. I am not sure why this would be an issue. I could make flat plates to shrink the height and other blocks to create walls to shrink the total floor space. I could cast these either out of Kast-o-lite or GreenKleen. Probably Kast-o-lite as it is more insulating and wouldn't suck the heat as much. 

I have looked at induction. But I am going to hold off on anything like that until I master these other methods a bit.

Thanks.

[Frosty]

I think my ISP is glitchy, the only picture is saw was the Sandia recuperative so that's all I could comment on. 

I don't care about BTUs, I caare about temperature. Of course psi counts, the higher through the same orifice the faster the flow. No? My experience with these two burners has shown me that too slow and the block heats to the point the rate of propagation is higher than the velocity of the flow and it burns back into the plenum. That's not theory it's empirical fact. It is however in MY two burners, can't say about other's.

How much do you think you can forge at one time? Heating high carbon steel above critical temperature and NOT refining the grain under the hammer causes grain growth and embrittlement. Unless you have a power hammer it's hard to forge more than 4-6" of a blade in a heat, you don't want to be hitting it too cool. 

I can easily slip a 12" wide ax bit 9" into my 700 cu/in NARB forge and it's a little too large but not bad. 

https://www.iforgeiron.com/topic/48314-narb-lives/

The orange dragon's breath is the calcite binder in the refractory burning, it faded considerably as it cured.  NARB stands for Naturally Aspirated Ribbon Burner. The ribbons are driven by Jet ejector type inducers built to my T design. I developed the T burner to be easy to build with minimal shop skills and equipment and be effective. There are more effective NA burners of course but this is one serves my purpose nicely. Good for guys to get into the craft without having machine tools or the skill to use them.

Frosty The Lucky.

 

[thematrixiam]

2 hours ago, Frosty said:

I don't care about BTUs, I care about temperature.

Temperature is where something is.

BTU is how it got there.

You care about BTU. That is what does the work. You can never reach temperature X without BTU Y.

 

 

2 hours ago, Frosty said:

Of course psi counts, the higher through the same orifice the faster the flow. No?

Absolutely. I agree 100%. An orifice is a "fixed metering device". The only way to get more through the same size hole is to change pressure. 

These numbers are all at 10 psi.

0.0147

0.0590

0.230

0.940

2.030

3.610

8.130

14.45

22.50

32.400

44.200

57.700

 

at 10 psi the chart gives us a velocity of 23.60 FPS (feet per second)

the left side is 1/64" orifice.
move down the line to the number that says 2.030... and that is 3/16"

That is a difference of 2 gallons of gas per minute.

so, yes. PSI does affect it. But orifice size makes a bigger impact.

 

2 hours ago, Frosty said:

the rate of propagation is higher than the velocity of the flow and it burns back into the plenum.

What do you mean by plenum? That is a term used in my trade quite frequently. I have installed and made from scratch hundreds of them. But part of me thinks you mean something different.

I do agree, 100% that the rate of propagation is important. You do not want lift off or flashback.

 

3 hours ago, Frosty said:

How much do you think you can forge at one time? 

Translation: "I think you're forge is too big"

re: adding and removing spaces to lower or raise forge volume on demand. 

Do you think it is possible to raise or lower a forges volume on demand?

I do. 


As a side note. I also believe it would be possible to make a forge 10 feet tall by 10 feet wide by 3 feet deep. The more you increase the insulation the more you can decrease heat loss. If you forge based on radiant temperature of the air, convection of the room, conduction of the walls/shelves and not direct line of fire or touch to the flame. It probably wouldn't work with propane though. But you would be theoretically be able to bake your metal at the set temperature of your choice with minimal variance. You could design it such that once it got to temperature it stayed at temperature for a long time, as well, with minimal loses. ... Actually, you could build it with propane, it would just take longer to get the room to temperature. 

Wow... check out these guys
https://www.forgemag.com/articles/84723-furnace-and-regenerative-combustion-design-in-open-die-forging

That forge is something! "28 feet wide x 31 feet deep x 15 feet high."

Ideally, at some point I make my own power hammer. It would be lovely to be able to pump out my own anvil as well. Unfortunately my forge would be way too small for that. At which point I would have to make a third forge. I am curious if it would be cheaper than buying an anvil? That said I can always sell them if I can make them. That would probably never happen though. I am dreaming too big.

Part of me feels that this discussion is more about people clipping their wings, and less about "empirical fact(s)"

re:

3 hours ago, Frosty said:

That's not theory it's empirical fact.

 

[MCalvert]

I would recommend reading the consolidated notes (Lou's sticky) and Burners 101 so that when you make a 300-400ci forge to use the other 99.9% of the time you forge, it will be a well-built and useful tool. I hope your behemoth turns out great, and please post all the trial and error so that we can learn from your testing the limits of normally-sized burners in such a whopper. Good luck to ya!