Burners 101

[Buzzkill]

I'm really intrigued by the last burner shown.  In my mind at least if you can successfully introduce a "sheet of flame" of high enough temperature into a forge with minimal opening requirements for the burner mount that could be something close to ideal for producing even heat in the forge.  What's the sound level like for that one compared to a ribbon burner or standard single port burner?

[Frosty]

I like the look of the flame in the last pic but the jury's out till I see it in a forge. The plenum you have between the mixing tube and the flame nozzle is accelerating the fuel air mix / flame. Compression = velocity which is a good thing in a rocket engine but not so in a furnace. The longer the flame stays in the furnace the hotter the furnace walls get and the less fuel it uses. This is the essence of a "reverberatory furnace" The flame heats the furnace walls, IR heats whatever is in the furnace. Iron and steel in our case.

I haven't taken dividers to the comp screen to determine the cross section areas but it looks from here like the outlet is smaller than the mixing tube. This gives it a slight pressure drop as The F/A (Fuel/Air mix) enters the plenum and then an increase as it reaches the outlet. A high flow rate MIGHT keep it from burning back once things get HOT, maybe not. 

Frosty The Lucky.

[Mikey98118]

Small high speed burners can be combined with swirling the exhaust gases around a tunnel shape to increase hang time of the flame; if we are looking for increased overall temperatures in a small forge, this path can more than compete with multi-flame retention nozzles ( such as ribbon burners). If we are looking to heat larger equipment to moderately high temperatures, than the efficiency of multi-flame  nozzles (especially ribbon burners) will likely outperform high speed tube burners.

The mad scientist in me always once more heat and compact equipment...but we have long surpassed any logical need for either in mainstream forge construction. Multi-flame nozzles are probably the future.

Furthermore, the short flames of multi-flame burners can be used to increase the utility of clam shell and other specialty forge shapes, since the most convenient position for them is likely to leave high speed single flames  impinging on the work.

Progress requires us to be dispassionate about our favorite tool designs; both in choosing them, and in letting them go when they have outlived their usefulness. I like having my druthers as much as the next guy...until they get in the way; then ruthlessness is what it needed.

However, the jury is still out concerning your latest burner; you need to look into it further. Also, scrap kiln shelves could be cut and replace the steel in your burner; thismight improve its performance enough to make clean burning flames. Utility can only be judged in a forge...

[Ted Ewert]

I'm leaning towards a ribbon burner in the next forge. It would be a single line of outlets tangent to the radius of the chamber. The diameter and number of the holes is the only thing I have some questions around. It could be cast it right off the pipe.

Anyway, here are a few shots of the burner in question in the forge. The flame didn't turn out as bright as it looked to my eyes. I guess my camera sensor rolls off a little towards the UV spectrum.

The threaded rod splits the flame a bit, which could be minimized with more careful fabrication.

Here's a side view:

Here's the simple setup I have. That blue handle is on a needle valve (not a common hose bib). All my valves are 1/2", which makes things simple as far as connecting the string together. 

 

Ted

[Mikey98118]

It looks like you are already well set up to mount a ribbon burner to your forge. I would read thoroughly about them, starting with Wayne's page, before making yours.

[Ted Ewert]

The ribbon burner would be for the next forge I build. This one is just a test fixture. I'm going full refractory on the new one. I have an old air tank and lots of insulation. I still have to get some cement and a few odds and ends, but it's coming. 

[Frosty]

CEMENT? In a forge?! Even high temp furnace cement is NOT suitable in a gas forge, it's for sticking things together NOT exposure to the fire. You need to use high alumina water set refractory which is formulated to survive the fire. 

The current common consensus is Kastolite-30 Li is the best commonly available refractory for what we do. It's a: 3,000 f., water setting, castable, high alumina, bubble refractory. It is rated for max continuous operating temp of 3,000 f. and is concrete hard in operation. Being an alumina refractory it is pretty much immune to high temp caustics exposure. Welding temp borax fluxes being what we do to our forges Kastolite products just don't care.

Frosty The Lucky.

[Ted Ewert]

That's what I meant Frosty. I just couldn't remember " high alumina water set refractory " at the time. I'm just getting ready to order some so thanks for the info.

[Irondragon Forge ClayWorks]

Welcome... I always suggest this thread to get the best out of the forum.

[Ted Ewert]

On 6/12/2018 at 8:49 AM, Frosty said:

Compression = velocity which is a good thing in a rocket engine but not so in a furnace. The longer the flame stays in the furnace the hotter the furnace walls get and the less fuel it uses.

I think a good burner is a lot like a rocket engine. The fuel has to get accelerated beyond the velocity of the flame front in order to keep the flame out of the burner, and inside the furnace.

You can see in this picture that the gasses get compressed then expanded into the nozzle. The nozzle then shapes and directs the flame. We should be designing and building our burners with this general concept in mind. Our nozzles can be any sort of contained expansion area which shapes and directs the flame to our advantage. The nozzle should probably be cast into the chamber to increase durability and follow the natural contours of the chamber. The problem most people have with velocity is blowing the flame away from the nozzle. This condition can be mitigated through the use of turbulence inducing materials or shapes. Slowing down a portion of the flow in order to maintain the flame close to the nozzle insures a complete burn of the fuel before it escapes from the furnace. It also make the flame a lot hotter and more efficient. 

 

Ted

[Mikey98118]

Generally, I view flame velocity as an excellent marker for potential flame temperature; the faster the flame front the hotter it will be.

That said, making flames hotter by making them faster reduces "hang time". Blowing nice hot flames out of the forge's combustion chamber so fast they don't have time to transfer much of their heat to the chamber walls is counter productive. It's all a balancing act, as so much to do with heating equipment is.

And so we have ever more effective schemes for lengthening the flame path as much as possible (tangential positioning), and slowing the flame post combustion (ribbon burners).

I have admired the Frosty "T" burner design every since I saw a perfect SOFT flame coming out of one of them that included the right flame retention nozzle, because it does a wonderful job of combining high heat and slow exhaust. BALANCE, BALANCE, BALANCE! When we get to striving with each other it is time to take a deep breath, step back, and look for balance; in our views and the other guys.

There is no such thing as the perfect burner for every purpose; that doesn't mean we should stop trying for them though 

[Ted Ewert]

 

33 minutes ago, Mikey98118 said:

Generally, I view flame velocity as an excellent marker for potential flame temperature; the faster the flame front the hotter it will be.

If you have a stoichiometric mixture, it seems to me that the flame front speed is pretty much fixed. IMO, keeping the flame lit at the nozzle is key (more of a problem with blown burners). Once it leaves the nozzle unburned it mixes with the surrounding air and quickly becomes non stoichiometric. 

If I get a blue flame right off the nozzle, and no orange, I know I have a nice hot, clean burn. 

[Mikey98118]

Flame front speeds are only fixed as regards fuels chosen and amount of oxidizer used; not regarding burner or rocket engine design, or do you want to try contradicting your own premise now?

A proper fuel/air mixture is a given for this discussion, and I suspect that your opinion is neither humble or sound.

I think your don't realer want to discuss this subject. I think you just want to argue.

[Charles R. Stevens]

Sounds like a mechanic, or at lest a hot rod gear head,  Mike. Lol

If I remember my basic chemistry and internal combustion engine theory stoichomitry refes to an equation used to calculate the volume of a gas at a given tempature, having little to nothing to do with the speed of the flame front. Fuel rations have little to do with flamfront spread either but a lot to do with stoimetric effecency (the more higher the percentage of fuel oxidized, and the higher potential BTU,s contained in the fuel the more heat generated, the greater the expansion of the combustion byproducts). 

Now for internal combustion engines flame front speed is paramaount, as it is a fixed factor in the production of effecently power. The faster the engine runs the less time the fuel has to burn befor the combustion chamber vallume expands. For this reason long rods, short crank throws and tall blocks produce more effecentl power at higher RPM because the piston dwells at .001” of TDC linger, in the sense of of the degrees of crank rotation. Obviously this is why advancing the timing is so important as engine speed increases and retarding it as it decreases ( that and destination witch is detrimental to gas engines. Now my Dad could speak more athoritivly on jet turbines than I.

as to naturally aspirated burners for forges and furnaces, Mike literally wrote the book Jerry most likely ate the dang thing). 

[Mikey98118]

On ‎6‎/‎12‎/‎2018 at 8:34 AM, Buzzkill said:

In my mind at least if you can successfully introduce a "sheet of flame" of high enough temperature into a forge with minimal opening requirements for the burner mount that could be something close to ideal for producing even heat in the forge.  What's the sound level like for that one compared to a ribbon burner or standard single port burner?

I don't doubt that a sheet of flame can be valuable, if someone takes the time to pursue its uses. 

Flame noise only appears to be a major problem; it can be manipulated as easily as the flame is. But the easiest way to handle flame noise is to dampen it. Unlike flame heat, sound waves travel in straight lines, so things like baffle walls can be used to dampen flame noise the easy way.

'Dampening' flame noise is trickier, because it involves burner changes, which may or may not be wanted.

But getting back to how a sheet of flame might provide release from noise, I would suppose that if the flame was faced with the wide face parallel to a curving surface, its noise would be dampened quite a lot better than that of a standard circular flame 

I suspect that heat transfer into the forge surfaces would also benefit from this deal.

[Mikey98118]

 

this burner design could also benefit from use of kiln shelf parts, cut and cemented together for a combustion chamber. Changing its steel parts for a tough enough ceramic to be used this way, would bring it up even with ribbon burners in ability to take advantage of the latest forge materials and fuel gases; these will become popular in the coming years, so burner designs that can't employ them will become second rate.

[Frosty]

Here you are Mike. In future if you think something I posted should go here or Forges 101 orrrr the dumpster you have my permission to click on "Report Post" in the upper right of that post, next to the little < looking symbol, and ask Admin. to move it.

Below is a cut and paste from another thread about possible causes and fixes for burner problems in ones that have been sitting for a while.

If it's been sitting idle for a while clean the burner out, including the jet. Critters like nesting in burners and spiders have been known to nest in the propane lines after crawling in through the jet. Disconnect the gas line at and remove the jet from the burner. You can hold it up and look at a bright light through it if you're careful. One squint at a light bulb or the sun and you're eyes aren't going to adjust for a while. You have to cup the fitting so the only sight line you have is through the fitting and jet.

Clean it gently with a stiff bit of fiber from the outlet end of the jet towards the fitting or carefully try blowing it clear with an air hose. ONe of those ball filler nozzles works well but be VERY CAREFUL or you might inject air into a finger or hand! This is a B-A-D-N-E-S-S THING!! 

I used to blow them out by mouth till I blew a bunch of just hatched baby spiders out on the piece of paper I used to get a look at any debris I cleared from the jet. I am not normally terribly afraid of spiders but discovering I put maybe 30 of them in my mouth had me dancing and spitting frantically while I cussed. I think I may have actually been flapping my arms too. 

The jets in my 3/4" burners are 0.035 mig contact tips and my torch tip files are perfect for cleaning them without messing them up. I've never put one in my mouth again.

Anyway, Make sure the burner is clear and clean before looking for something odd, they're good quality burners. Heck the regulator may need replacing, check it all, from jet to tank. 

Frosty The Lucky.

[Mikey98118]

Thanks for relating that here, Frosty; it's good stuff.

Folks, it is necessary to understand that a Frosty "T" burner uses a larger bore in its MIG tip than most burners do, because his burners have different flow characteristics; choices need to be right and proper for the burner design they serve. I have seen some confusion about this from people who tend to grab the facts and run with them. More excellent burner designs are cropping up all the time, and it is important not to mix parts or rules of thumb in their construction.

[Mikey98118]

Finding MIG Contact tips or doing without

How to deal with American, Imperial, or Metric measurements? Just input "inches to mm" to take your choice of online calculators. Input "pipe chart" or "thread chart" to find the closest part us Yankees are talking about in your local market. The only critical measurement you will encounter is the bore diameter of the MIG tip you will use for a gas jet; Fortunately that is one of the most common parts in any market; .035" which is a call-out size. MIG tips are not given in actual bore diameter, but for the weld wire size they are used with. The actual hole size of this tip is .044". These dimensions are for the MIG contact tip used in a 3/4" Frosty "T" burner. Also, unlike most burners, a "T" works just fine with short MIG tips, finding long a tip is the  usual problem encountered on your end of the pond.  Fortunately the bore diameters of European and Asian manufactured MIG tips are nearly identical to those available in America.

The only point to employing MIG tips is to provide a convenient part source. When the right part isn't available, simply find some half-hard brass rod and bore your own hole into it. A 1-1/4" long hole is equivalent of a short MIG tip. A 1-3/4" long hole is equivalent of a long MIG tip. "half-hard" is the most common form of brass parts around, just because they machine and drill more cleanly than other brass alloys. a .044" drill bit is more than large enough to  be carefully used to drill a 1-3/4" long hole in a 1/4" diameter rod of this alloy. This rod can than be threaded and screwed into a  burner's gas tube, or soldered in.

[Mikey98118]

Gas pipes

The best American pipe to mount your jet on is schedule #80 1/8" pipe; what matters is its inside diameter, which is approximately 3/16". You can use any pipe or tubing product that has an inside diameter of about 3/16" and it will conform properly with standard MIG tips on both end of the pond, to work well.

There are smaller diameter Asian tips, and products meant to be used in their MIG gun designs, which call for even smaller tube. Make use you are provided with their thread measurements before you go hunting for something to use as a gas tube for them.

[Mikey98118]

Nominal (call-out) pipe sizes don't ever match actual measurements; pipes were classified (standardized) in the eighteen hundreds, when the strongest steel alloys around were little better than wrought iron. Pipe had much thicker walls back then. Outside diameters of pipe had to conform closely enough for threading tools to work on the products of different manufacturers. So as pipe walls could be made thinner and still withstand needed water pressure, actual inside diameters grew until they had little to do with nominal diameters.

During all that time,Great Brittan's Imperial system, and the rest of Europe's Metric system were competing for dominance,while undergoing the same size changes made possible buy their steel alloys  And fun was had by all

[Troylet101]

Can someone PLEASE tell me EXACTLY what mig tip uses, OR will somehow work with 1/4 x 28 tap??? Lincoln is a no-go... every Tewco I can find are too small as well and I keep reading that Miller's won't work either!!! Building Frosty's T - Burner and 1/4 x 28 is about the only feasible size to tap the 1/8 fitting. Brass is expensive and I'm about outta "live and learn" money!!! I need FACTS!!!

Thanks in advance!!!!

 

[Frosty]

Tweeko Mig contact tips are SAE threads. If all you can find are metric but the correct tap at the welding supply where you get the tips. It's pretty common to need to chase out the threads in mig guns so welding supplies carry them. Don't be surprised if the counter people don't know anything more than these are what: Lincoln, or Hobart, or Miller, etc. use. They  have other things to keep in memory, the appropriate bits, taps, etc. are all marked. Heck, the only reason the guys at the local Aire Liquide know 1/4" x 28 means is because I'm a likable story teller and have talked their legs off often enough.  If all you can get are metric threaded mig tips then use a metric drill bit and tap. They should have them there.

Frosty The Lucky.

[Troylet101]

Thanks Frosty, I appreciate your help!!! The problem I'm having is that while I can tap the the fitting for metric, the inside of that 1/8 fitting is just large enough that there isn't enough "meat" to get good crests on my threads and the tip will just slide in and out. When tapping 6mm, I can literally hold the fitting in my hand.... no vice!!! I tapped some brass caps when I first began this project (before I decided to follow your build) and all turned out well, so I know I'm sized properly for metric tips, provided there's a correct sized hole. Unfortunately, I have to tap for 1/4 to get a good bite with these particular fittings, but it seems that every flippin' mig tip I find, is 6 x 1mm!!! I keep reading that Tweco tips are 1/4 x 28 (or at least some) but there just isn't any info on the thread size for mig tips!!! I'm hoping someone can provide the model number or something of a tip that is definitely the right size as I just can't afford to keep wasting brass trying to figure out a work around!!! Short of that, I'll have to make a welding supply house run and just nose around until I find what I'm looking for!!! They seem to be few and far between in these parts however. You'd be amazed at how much more hardware etc. can be found in a small town vs. the 4th largest city in the country (Houston)!!!! Talk about frustration!!!!... Thanks again Frosty!!!

Troylet

[Mikey98118]

2 hours ago, Troylet101 said:

I keep reading that Tweco tips are 1/4 x 28 (or at least some) but there just isn't any info on the thread size for mig tips!!!

Actually the thread is 1/4-27; they only work in threaded holes from standard 1/4-28 taps because the MIG tips are soft copper and the two threads are close enough that the soft thread can change to match up well enough to avoid cross threading. However, you can buy 1/4-27 taps as cheaply as the standard 14-28 ones all day long these days.