Burners 101

[Trevor84]

AFB thanks ya they're for holding RR spikes by the head. So far they seem to work fairly well. 

[Mikey98118]

Air swirl is where it all begins

The most practical method of maintaining an even temperature in a forge or casting furnace, or mixing fuel gas and air in a burner is swirl. But if that swirl happens through a constriction, such as a reducer fitting, funnel, or "T" fitting that is mounted so that a smaller outlet than its two air inlets is connected to a mixing tube...

The power of swirl is joined to the magic of vortical flow.

If you add just one more tiny detail to this picture, the benefits become dramatic.

The "T" fitting does this automatically, because its two larger air entrances introduce air from opposite sides of a reducing exit. It takes less energy for air to start swirling into a hole than it does to compress, and so rotation is formed early in the process.

A Vortex burner employs the impeller blades of a computer fan to create swirl at the air entrance of a burner's funnel opening.

'You can even cut and bend a can lid, into a crude fan shape, and place over a reducer fittings large opening and improve burner performance; trumpet shaped opening? DITTO, for the same reason. EVERY LITTLE TRICK YOU CAN FIND TO START SWIRL AT OR BEFORE THE AIR TRANSITS THROUGH A REDUCER WILL JUMP PERFORMANCE, PERIOD--NO EXCEPTIONS.

Air swirl first + reducer shape second = dragster

 

 

[Mikey98118]

Putting on the brakes

A hard flame, is essentially a controlled explosion; it creates a weak force. But the outward push of a gas flame isn’t equal in all directions. The gas/air mixture is being flung forward, so there is a little more shove away from the burner’s end, than in any other direction. All things being equal, the harder the flame is tuned the faster the gas/air mixture will rush forward, and the greater that imbalance will grow. At some point, the out flung mixture will force the flame far enough from the ignition source to snuff it.

    Atmospheric pressure is a constant force all around the flame.  But,  create a low pressure area at the burner’s exit (by use of a flame retention nozzle), and atmospheric pressure will press the flame harder against that one area than all others; the difference isn’t much, but it is enough to allow much harder flames to be used, because the kinetic force of the air and gas molecules are also minimal.       

[Bearded Welder]

Hello everyone! 

My name is Phil and this is my first time posting, but I've been lurking on this forum for a couple months now and have read the forges 101 and burners 101 a couple times and before that have done 400+ hours of research on forge and burner building from various other sites (until I found this one)

First let me just say that I, as well as many others I'm sure are so very grateful for the people here whom their expertise is freely given and shared and enjoy doing it.I have learned alot (I hope) 

I wanted to try and do as much of this on my own so I could learn through trial and error (without blowing myself up!) doing my own independant research is important to me, but at the end of the day you can't replace years of knowledge and experience so I am now going to break my extreme shyness and post something on the internet (which I've never done) to seek opinions and thoughts on what I have created. 

My specs for this burner are 1" mixing tube, 9" long. It is technically stainless pipe that I got for free and I TIG welded mild threads on either end. The nozzle is 316 Stainless 1 1/2" step variant with a 1 1/4 spacer ring. The "intake head" is something I ordered from China a year ago because I thought at the time hey this will work, I cut off the top of it and used a Dyna file to bore out the funnel Shape to get the large end bigger (too about 2.5") and then TIGed it back on, its made out of some sort of aluminum cast. I used a 1/8" sch#80 4" 316 stainless nipple for my gas tube and threaded the entire thing for depth adjustment of the jet into the head, I tapped into the end a 1/4-28 mig contact tip, tried a. 035 tip first but then went to a. 044 taper tip after I didn't like the results of the. 035. The air choke is a wavy bent priece of aluminum that travels up and down on the 1/8" jet tube assembly for control of air flow. I'm hooked up to a 20lb propane tank for now and have a 1-20 psi regulator with a gauge. All tephlon tape you see is gas rated and I used some tephlon tape on the outside of the 1/8 nipple to make it "travel tighter" through the top of the intake head if that makes sense.

this first picture is with 5 psi, half choke and exposure turned down on my phone

 

This is same settings but with normal camera settings, what I actually see in this picture is almost completely blue and no green. 

This is the "intake head", I have to switch out my ball valve for a gas rated one, just using this one for testing. 

So this is my step nozzle, it's a bit differant as I took a small bit of 1inch coupler for thread, and TIG welded the 1 1/2 pipe to that so it's a threaded step nozzle, kind of a hybrid between Frosty's thread protector nozzle and Mikey's step nozzle. My one main concern is it is slightly too long but I'm waiting for when I have time to do small trim tests on it. 

Slightly richer (by way of the air choke) but with a flash on my camera

This is rich, it isn't as green as the picture but definitely had some green in it, also at 10 psi. 

I don't know what this is... I have the air choke opened all the way so I assume it's reducing but I also have it at 2 psi, it isn't chugging though it does at 1.5, so yeah.. What does anybody make of that? 

MIG tip comes to about the top of my finger nail

15 psi, less exposure

Inside of the nozzle which from the end of the threads to the beveled tip is 2" 7/8ths, which I think is too long since one of the recommendations for the Mikey step nozzle is 1/8" to 1/4" larger than mixing tube diameter for over hang, but I thought I would try anyway because I can always make it shorter. 

So that's all I have to share for now, I look forward to anybody's thoughts and constructive criticism (even if it isn't constructive, call me a dolt if you need to!) 

Cheers! 

The Bearded Welder

[Frosty]

Welcome aboard, glad you delurked! I must say that is one heck of a first post! 

I can't think of anything to criticize about your burner, it appears to be working beautifully. Your first pic with the light turned down o your camera/phone is the first time I've seen all 3 burn zones in I don't know how long. Well DONE! The pesky things are there if you can see them or not. HAH!

The pic at 2 psi is running rich because the propane jet isn't moving fast enough to induce enough air for complete combustion. Nothing wrong, it's just below it's effective psi range, bellow effective turn down. 

It's beautiful, well done!

I have a question though. Do you know how large a forge that monster needs? It MIGHT turn down enough you won't need a crazy large forge but . . .

Frosty The Lucky.

[Mikey98118]

Frosty has it right. You win the blue ribbon on your first try. As to the flame variance; that is normal, and even desirable, once you become familiar with the burner. We are all looking forward to seeing your first forge, too

[Mikey98118]

Reviewing the obvious

It is obvious that:

Smaller first forges are better, even though we are always tempted to build the opposite.

Smaller forges need smaller burners for maximum efficiency.

Since smaller burners tend to run hotter than the same designs in larger burners, the our first concern should be how easy they will be for us to build, rather than what design is hottest.

Linear burners are the easiest designs to find parts for in the smaller pipe fittings, when made with a cross pipe for its gas tube.

The MIG tip modification greatly improves performance of linear burners; over drilled gas holes in the cross-tube.

MIG tips are too long, with orifice sizes to large for to be handy in really small burners (3/8" and under).

3D Printer nozzles for gas orifices in burners solves both problems, and are the cheap and easy OBVIOUS key to everything presented here

[Frosty]

I knew we'd talked about jets for smaller burners than 1/2", I recall 3D printer nozzles now. 

Come spring and getting the shop hooked to electricity I hope you'll remind me. I have the memory of a camera flash.

Frosty The Lucky.

[Bearded Welder]

Thank you both Frosty and Mikey! I'm glad you gave it the seal of approval! 

I think I can see the three zones you are referring too, took a while to understand what I was looking for but I think I have it know. 

So Frosty, in terms of not inducing enough air for complete combustion, what would happen if I went down 1 size of mig tip? That would pull more air correct? Giving me a higher turn down range, but possibly not getting the max heat this current set would give me..? Am I understanding that correctly? 

My current forge is actually almost finished, unfortunately with this whole virus businesses I'm waiting a month for my fumed silica to arrive, but I have everything else, kaowool, a refractory which I hope will be sufficient and I custom made the shell from stainless sheat metal (I work at a stainless cabinet production facility) I'll upload a picture of it possibly tonight, I'm looking at 3" of kaowhool, and after doing the math it will leave me with an inside volume (after kaowool) of about 1300, so I will have 2 burners, but I'm also making everything about my build variable, there will be an internal baffle wall to slide back and forth depending on my size of work, I do admit I went a little large on the build but I wanted more kaowool than average to better insulate..im also trying a recoupritive(not sure on spelling) design which will pre heat the propane as it goes into the burner, though rest assured it will easily be by passable if it doesn't work and I will be doing some very specific testing for saftey purposes as to not reach the flash point of the propane. I am excited to post a picture of it all, should I post here or else where in the forum? 

Cheers

The Bearded Welder 

[Bearded Welder]

Apologies if this is the wrong spot to post this being the burner thread but here are a few pictures of my forge shell I made from 14 gauge stainless. The secondary floor inside was because after building the outside shell and doors, I realized I went to big (still probably did but that's ok since it will have the internal baffle wall) so rather than cut everything up I just put a high floor in cutting down on the volume, not quite a D forge and not quite an oval forge so we'll see how it works. Used a break press to fold in the creeses to get the round shape, welding the 2 halves at the top and metal finished it for a seamless look welded together the set screws out threaded stainless rod, and the odd looking thing on the side is a clamp I made to hold the stainless steel line for the propane. The small nipple coming out of the top is for a heat exsaust which I'm hoping will preheat the line so the propane is about 400 degrees as jt goes into the burner. Incase it wasn't obvious ha! Ive tried to keep everything stainless from top to bottom as its the material I had the most access to for little to no charge. 

I have probably went a little over board but I love to tinker and make things so I figured why not put as much of myself into this project as possible. Sorry for the lighting, it's not great in the shop at the moment. 

Cheers! 

The Bearded Welder

 

[Frosty]

You HAVE been reading haven't you? 

Reducing the jet diameter might tune it to run at a lower output, unfortunately it will be unusabley lean if you turn it up. Every power tool has a minimum setting I wouldn't try for less than minimum. 

There's a point of diminishing returns where Kaowool is concerned, the improvement from 2" to 3" is negligible, at high yellow heat I can touch the outside of my forge for a second or so without getting burned. Mine has 2 layers of 1" 8lb. Kaowool with 1/2" Kastolite 30 hard refractory inner liner. I don't have a kiln wash in this one and you can touch the outside shell. 

That's "recuperative" meaning it recoups waste / exhaust heat but there's a practical limit to preheating combustion air OR propane. 2,000f is flash temp for propane in air. Most folk have given up on recuperative combustion air preheating, it's just too easy to make it efficient and have your burners start preigniting and pfzzt.  Preheating the propane is more effective as hot propane mixes more thoroughly than ambient/cold. If you figure out a good method I'll be very interested.

1,300 cu/in volume! Good GRIEF MAN what do you plan on forging: crank shafts, anchors, wrecking balls. . . ?  I can bring a 2" x 2" x 10" piece of steel to welding temp in mine but there is only so much you can work at a time. The closest I've come to that is heating a piece of 2 1/2" rnd bar to almost red to preheat the quench tank. An experienced smith can effectively work maybe 6" or so in a heat by hand. Steel brought above critical temperature without being worked under the hammer suffers grain growth, crystallization, which leads to brittle steel. 

A 700 cu/in volume forge under one of your beautifully effective burners will be WAY more forge than you're likely to need unless you end up running a production smithy. Even then. As seen in your pictures it already has excellent turn down range I'd see how it worked in a 350-400 cu/in forge. Just because you have a monster burner doesn't mean you have to use it all. 

Frosty The Lucky.

 

[Bearded Welder]

I try Frosty, I like to soak in as much as possible. That's good to know, I'll stick with my current design then! 

OK well to be a 100% honest  I built the forge before the burner so in essence I made the forge to large and then the burner to match, I hope that with the variable baffle wall I will be able to bring the size down to a more managable size for smaller stuff, I'm hoping around 600 cu/in, maybe I should have listened to my gut and made the secondary floor even higher up.. I can always put 4 inches of kaowool in it to bring the volume down even further? Not necessarily for the insulating factor as you have stated here and in other posts that past 2 inches there isn't much point.. My goal was to do exactly what everyone here advises against and build an all in one forge.. Shame on me for not listening... So once it's finished I will see how large of a hole I dug for my self.. Im looking at ways to be able to temperarily make the volume even smaller, by possibly sliding in insertes of refactory to fill the volume up.. But we'll see how those experiments go.. 

I did realise about the whole "can only work so much metal at one time" thing, so I'm hoping the baffle wall with a small hole will allow me to heat smaller sections of what I'm working on and then if I'm doing larger things or heat treating I can take the wall out/push it all the way to the back.. My main focus will be knives, but who knows, anchors sound fun! As well as ornitmental iron work! 

I will post the build after it is finished and hopefully show the recuperative aspect working well. (fingers and eyes crossed)

I also have something else in the works to induce swirl into the top of my burner intakes via a cyclone forced air type of rig... Running off a little battery pack welding belt for clean air into the welding helmet, highly mobile. I will post pictures of that once I work out the kinks.. 

Cheers! 

The Bearded Welder 

[ThomasPowers]

For about 20 years now making knives; I've been using  an 11" diameter x 14" long shell with currently two layers of kaowool and a KoL30 coating. As the back door opens I can even make swords in it.  I don't see any reason to pay good money to heat area I don't need. Shoot I've used it to teach 5 students at the same time.

BW if you have that much money to throw away on propane why not buy an induction forge and run it with an inert atmosphere?  Make us all jealous rather than incredulous.

[Frosty]

Uh, there's a new one, you built the forge shell before knowing how much burner you had or needed?  Oh MY, there should be a term for that sort of thing. Hmmmmmm. Maybe something about a horse and a wagon? Nah, too vague, I'm open to suggestions. You knew it was too large and why as well. . . 

Dang I think that makes you a blacksmith! 

Filling the floor pan to reduce the volume is the easy way. 2" of kaowool will allow you to use something less expensive under it. The SS sheet floor will be a little flexible  so blocking it up from below will add life to the floor.

Knives? in a 1,300 cu/in propane forge? !  !  !  !  !  !  Are you sure you don't want to make a damascus great sword to learn the craft? 

A forge with the volume of a single brick ID=, 2 1/4"  x 4 1/2" x 9" is more than enough forge for most usable size blades. It typically takes 5-6 K-26 IFBs and a soldering torch to build one. Of course a heat resistant table is a good thing, say a piece of sheet rock on a wooden kitchen table. 

You are SO going to fit in here. 

Frosty The Lucky.

[Bearded Welder]

 Thomas, is that 11" after kaowool or before so more like 11" minus 4" for either side of kaowool? Just trying to get a picture in my head.. 

Like I said, I've made it too big, but for the amount of work I put into it I would like to see it finished, I thought I might want to forge some big stuff now and again, I'm thinking of putting in a thicker floor of kaowool to bring the shape to more of a D shape, then if I want to in the future I can take out the temporary "thick floor" change the burner position since they are adjustable and forge something larger, then but the thick floor back in, worst comes to worst I'll build a smaller tube shape for knife making and keep this behemoth for large projects as most people here say they build multiple forges for differant tasks.. 

That sounds interesting but to be honest I wouldn't know where to begin, I know I'm getting a fairly large propane tank installed outside the building per the landlords request (we share the shop) I think it's a 400lb tank and he said it made more sense if we are both using it, it will be cheaper than filling up small tanks my self. 

I'm still learning little things about the trade, I went for hot and effective and large and never thought of the why behind it all. 

I'm going to try and make this forge work on a smaller scale with added kaowool just to decrease volume, if worst comes to worst I can cut it in half and make it a true D forge and that will cut the volume in half if not more.. 

Despite what my Wife thinks I'm trying to do this on a buget haha! Total amount I've spent so far for 2 burners and the forge with kaowool and everything... About 400 bucks.. I thought that was decent? Or am I way off the mark? Keep in mind the stainless is free or I would have taken a freon tank or something like that.. 

Thanks for the input 

Cheers! 

The Bearded Welder

[pnut]

Around four hundred bucks is the number I came up with for purchasing everything new to line a forge and build a burner if I didn't make any mistakes that would cause me to have to replace anything. 

Pnut

[Bearded Welder]

Frosty, I didn't see your reply till after my last message, 

Haha... Um yeah, I figured build the shell which I thought would be harder and then build the simple burner to match... Boy oh boy was that off the mark! Ha! 

All that horse power and no where to roam? That sound about right? 

Well I guess that's good news! I'm headed in the right direction! 

OK so I have a couple ideas then, I have some crappy hard fire bricks from a while back, could I set those in the bottom and then do the usual kaowool, backbutter, rigidize, refractory on top of that? Or will the loose bricks want to move causing my refractory to crack? Just spit balling ideas... 

Damascus is a goal I admit....but both that and a great sword will be a few years ftom now I'm sure! Ha

I'll keep the smaller size in mind.. As in the the front of my mind.. All the time... Everytime I look at it! 

Well thank you for the warm welcome, I was a little worried to be honest

Cheers

The Bearded Welder

Pnut, 

Good to know I wasn't too far off then! 

[Mikey98118]

7 hours ago, pnut said:

Around four hundred bucks is the number I came up with for purchasing everything new to line a forge and build a burner

I would only come out that high if I included some tooling for the job. Afterward we get to keep the tools

[Bearded Welder]

So this is my little contraption to initiate a swirl at the top of the intake reducer.. I think it's working but I need to change something else to make it work? This is only a prototype/concept, if it's viable I would make a more thourgho setup with properly placed I let's and the such. Thoughts are much appreciated!

Cheers! 

The Bearded Welder

[G-son]

Only the interior layers of insulation has to withstand the highest temperatures, if you add layers just to reduce size you should be fine using way cheaper lower temperature insulation for the outer layer.

[Frosty]

Bearded Welder, do you have a name or nickname we can address you buy? The Bearded Welder is a bit cumbersome I'm going to have to make something up. "Doc Brown? Mr. Teller?"  "Rube Goldberg" is too obvious but it'd do.

WOW! I'm thinking that's a Manhattan Project burner or maybe one Back from the Future. One of the reasons your burner works so well in the first place is because it already induces swirl. 

A few gears, levers and brass and you'd have a gloriously steam punk burner. I'd proudly use it at demos! 

Well said G-son, you covered it nicely. I'm too long winded and confuse people.

Frosty The Lucky.

[Bearded Welder]

Frosty, you can call me Phil, of course that goes for anybody.. 

 I could try and get my hands on some plutonium! That would really give me an edge I think! and I thought added swirl would be a good thing? Trying to mimic the concept that I read on the thread of the vortex burner but in just a differant way I guess.. Maybe I'm over doing it a tad? 

G-son, you idea of a cheaper insulation had crossed my mind but I'm not sure what kind of insulation could go on the exterior of the kaowool between it and the shell.. I'm assuming R14 pink panther won't cut it? 

Is there a cheaper less heat proof variety of ceramic blanket? I know of 8lb and 6lb and what I have is 8, but the price differance is negligable in my findings.. 

Thanks

Phil The Bearded

[pnut]

23 hours ago, Mikey98118 said:

would only come out that high if I included some tooling for the job

I'm tool poor so that definitely included incidental tools like taps etc. I would have to drive about an hour away to even get my drill so a cheap drill press wouldn't be out of the question. 

Pnut

[Mikey98118]

Regarding the burner; it works quite well, and that should always be the number one concern. As to how you got it there; you could spend years improving on the design, as some of us have done with ours...that is a personal equation

[Frosty]

Thank you Phil but I'd just get more confused if I called everybody Phil. 

Increasing the vortex in a burner is something we've been playing with for some time and Another Frankenburner has developed a SWEET burner, best of anyone here so far. Mike has experimented using computer fans to impart rotation to intake air. At one time I messed with putting vanes in the intake ports but didn't like my results at all. 

I don't think any of us thought of using a bunch of air jets though. None of ours look that cool either. No reason not to continue experimenting, we don't want to hog all the fun. 

G-son is right, on the other side f 2" of Kaowool you don't need anything special to take the heat though some things are NOT a good idea. Do NOT use Portland cement concrete, if it reaches much more than about 230f the water will for steam pockets and the concrete will crumble or even spall. Red bricks will work as will dirt. They don't have to be particularly good insulation nor take much heat. You just want something that doesn't move around to cause damage to the hard liner.  Fiberglass insulation would take the heat just fine but it's too soft it'd compress and the hard refractory flame face doesn't flex, it'll break up. 

Be careful to not get any plastic or adhesives in there, they're nothing but badness in the fire.

Frosty The Lucky.