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Mikey98118

Burners 101

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Good morning folks, I'm back with another build I'm in the tuning stage now and looking for thoughts on my progress.

3/4" Mickey burner with a 0.035 contact tip in a schedule 80 1/8" nipple and tapered to a point, mixing tube is 7 1/2" from the bottom of the air slots. The air slot area is divided into 6 and 3" long so that the solids are the the same width as the openings. The vertical the slots have opposing bevel's, like the sides are cut in the same direction. This just happened because of how I was holding the grinder but I assume it helps induce the vortex action, the bottom and tops of the slots have opposing bevels as well. Once I cleaned up these openings with a file I was able to see the vortex develop when looking at the flame straight on, you can kind of watch a ring of flame slowly rotate during ignition.

With this set up my flame itself seems pretty good but I am getting what looks like a lot of tertiary flames at times and lots of streaks. I've tried cleaning the mixing tube with a rag pushed back and forth in the tube with a few shots of brake cleaner. I think that some of the orange flame is still from residual oils because without touching anything and just standing watching the flame I can watch it go from almost no tertiary to a growing plume of orange flame that will back off eventually also if I tap the mixing tube I still get streaks. I think I need to try and clean the parts a bit more........... 1946356462_20200318_0807221.thumb.jpg.a2ca887e8d1cbfcace79852c60a0579a.jpg     

1178201462_20200318_0855061.thumb.jpg.702781997b91249ffc1984026bce2398.jpg

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With the same setting as seen in the previous pic but forge warmed up I was able to leave this shined up piece of metal directly under the flame for about 5 min with no scale formation. The flame becomes almost incandescent once the forge is hot with very minimal DB.579798943_20200318_1146191.thumb.jpg.4bb955db741c61abf6d0d1bc6a2726fa.jpg   

Here you can see the ring right at the nozzle, in a video you can see that ring slowly rotate but the flame has a nice cone shape from the side.392601026_20200317_1445271.thumb.jpg.13de70ace1c4eabe6683fbb1570b365b.jpg

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Flame's a little rich, it needs more air. I'd make suggestions but Mike adjusts his burner's the air fuel ratio differently than I do on. 

Frosty The Lucky.

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The last 3 pics are all without changing anything with the burner but the amount of orange will constantly change. In the forge the nozzle is cast into my liner however outside the forge I have a step nozzle on there. The nozzle is a 1" nipple with a 1/2" overhang then a 1 1/4" overhanging the 1" by about 7/8". The orifice seems to have the same outcome when I set it between 1/2" from the bottom of the air slots up to about 1 1/2". I have another jet set up with a .030 tip that I will try out tonight but in the meantime if you have any thoughts I am all ears. 

 

Frosty thank you. I wasn't quite sure about the color but if you're thinking that looks rich I will definitely try out the .030 jet, I always struggle judging the flame colors. Is the tertiary suggesting rich or the color of the blue?

 

 

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Moving the gas jet doesn't seem to have the kind of effects on Air Fuel (AF) ratio as it does with a T burner so I wouldn't mess with jet position, leave it where Mike says it should be.

The best looking though still rich flame is in the forge. However you've shaped your liner it's working well as the nozzle, you might try pulling the burner farther out by degrees. 

I'm not envisioning what you're describing for the step nozzle you're using outside the forge. If I'm not mistaken lengthening the final nozzle after the step increases induction, for a Mikey.

I'd play with the final nozzle or position in the forge BEFORE changing to a smaller jet. I THINK a 0.035 jet is pretty large for a Mikey but if you can get one adjusted to neutral it'll make him a happy camper. I'll also get to say "I told you so!:P"

Seriously, play with adjusting what you have ONE THING AT A TIME, then test and TAKE NOTES. Save making physical changes to the burner till you've exhausted adjustments.

Any time you see long feathery flames it's rich, whether there is orange or yellow in the flames. Orange AND feathery is like a rotating beacon. The color is opaque light blue indicating unburnt propane, water vapor and CO2 are invisible. A stoichometric (sp?) or perfectly balanced AF ratio leaving no unburnt fuel or oxy, propane flame byproducts are water and CO2. If the tertiary flame is visible it isn't really neutral. 

For my forge I like a SLIGHTLY rich/reducing fire to prevent scale forming IN the forge. Scale WILL form the second you expose hot steel to ambient air, no help for that but you certainly don't want your forge acting like a scale factory. Don't overdo though, just a LITTLE rich is more than good enough. That's getting down to fine tuning so let's get you in the ball park first.

Where IS Mike when you need him? 

Frosty The Lucky.

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When the burner is in the forge the current pieces I am using as a nozzle only act as spacers, they butt up to the flare in the liner. Outside the forge I just slid these spacers out into a multi step type nozzle just to see how it would act ( I do have other pieces to make a step nozzle as Mickey describes which will be used in future testing ).

Your description of the flame makes sense and adds to my ability to visualize what I am looking for. I guess the first thing I do tonight is going to be taking this apart and give it a clean again to make sure I have zero residue left to rule that out then put the proper step nozzle on and exhaust tuning option there before moving to the next step.

When it comes to the where the orifice should be, I have not found that measurement so I have just listened to it and it sounds like about 1/2" away from the throat may be the ticket there. With the 035 tip in there using the choke does zip until it's almost fully closed so no adjustment to play with there currently.

I do know from reading that the 035 is way bigger than what Mickey calls for so I'm not sure why I started there but it's an easy change if I can't find neutral.

Thanks again Frosty I'm sure Mickey will be around eventually, I got at least 9hrs before I can get back to it anyway........... that whole work thing ;)   

 

20200321_124304[1].jpg

this is how the current step looks like

20200321_125156[1].jpg

this is a rough idea of how the burner lines up in the forge, it mates up with the cast liner about an inch into the liner unlike how it looks like in the pic but this shows how the cast nozzle kind of looks

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The first point is that, you have already succeeded in making a very hot burner, in a very hot forge. I suspect that it is doing this well because you choose to update the air opening placement to three openings with wider ribs between them; smart move.

You have one, and possibly two major mistakes; the definite mistake is is your choice of MIG tip size. The book originally suggested a MIG contact tip for .O23" or .030" welding wire; these have .031" and .038" orifices, respectively. I noted in the book that one was a touch small, and the other a touch large, and suggested that a little work with a wire file from a set of torch tip cleaners would enlarge the smaller orifice to a perfect size.

In the years since publication MIG tips for .025" welding wire have come into the marketplace; with an orifice size, or .034". However, it wouldn't surprise me to find that, do to the improved air openings, your burner could handle a MIG tip for .030" welding wire. We do I think this? Because it is only running a little rich with the oversized .035" wire tip; so, really, that is a simple change.

The possible major mistake is the length of the mixing tube, which looks a little short; why possible? Because the position of the burner is foreshorten by the angle of the photos.

Are there other problems? Yes, but they are too minor, to effect performance in the view of perfectly sane people :D

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Hey Mickey "very hot" is a good start, I already have a .030 tip turned down so it's a real easy change over. I have not read your book only picked up dimensions here and there in this thread and others so I've kinda pieced those bits together.

The mixing tube portion (from the tip of the burner to the beginning of the openings) is 7 1/2" if that's too short I have another tube all ready made up that is about 8 3/8" so I have a little bit of option on length. 

Could you refresh me on how you determine a "very hot" flame? Is it because of the compact conical shape vs a looser flame that more or less blooms out of the nozzle? 

After I get these couple things dialed in I'll pick your brain on the "other" minor things ;)

Thank you

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Good to see you Mike, I'll now yield control of this thread to you. I can sit back and follow along. 

Frosty The Lucky.

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You should hold off on making a second burner, just yet. Why? You need to judge the advice you get in light of the coach's own shortcomings. My short comings are:

(1) I'm a well known perfectionist.

(2) I see the flame patterns in this kind of burner all too well at times.

A guy's hair could fall out waiting for me to see a perfect flame. The difference between a very hot flame and a perfect flame can be large, or it can be totally minor; it will always look glaringly obvious to me...but not matter a whit to how well your forge heats.

For instance, your MIG tip's gas orifice is slightly out of center to the burner axis. I can see that in nearly every photo. The reason it isn't the same in each photo is probably that the burner gets turned on that axis between shots. It is all very interesting, but pretty irrelevant to how that burner will perform in your forge :D

So, a sharp person will only follow me, until he reaches to his destination, and then jump ship!!!

Nevertheless, a very hot flame--from a high speed tube burner--has a single flame envelope--without secondary flame; it is also compact. There is far more that can be stated, and has been, but those are the first factors to look at. A "T" burner makes a different flame, which is also very hot. Another Frankenburner's deign probably has some difference in his perfect flame, and is almost certainly, the hottest burner around.

If you do decide to build a second burner, try shortening the air openings to about two-thirds the length you have. I deliberately  made the original openings a little long. The wider air openings also shorten the length needed; these two factors together, make shorter openings desirable, for those who want a better burner design.

 

 

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On page 78 of this thread, the reader will find a version of these burners, which departs in every detail from my design; it  produces a perfect flame. There is a time to listen closely, and a time to wing it.

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Nice burner Trevor.  As you know Frosty and Mike are the burner gurus around here and Frankenburner is the next gen. 
Once you know how to ride the bike it’s easier to go faster. I definitely second Miley’s suggestions on shorter intakes. With your current design, I would apply a choke to determine where max intake air intake is without making the flame “too lean and weak”. This mark is the max opening of the next build. If not enough, a file will get you where you need to be from there.

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671jungle is the guy who built the burner on page 78; if he ain't a burner guru, he ain't far from it :D

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1 hour ago, Mikey98118 said:

671jungle is the guy who built the burner on page 78; if he ain't a burner guru, he ain't far from it :D

Aw shucks :rolleyes: I don’t what to say. Thank you Mike.

I’ve learned that the mind is very capable if one is receptive and unbiased. The teacher plays a big role in proper translation of the knowledge and sometimes wisdom. 
Combustion fascinates me! Always has. There is a sweet window in an optimal burn whether it be solid or gas fuel. I’ve always said at bbqs, campfires and full moon parties:ph34r: that there is a science to building a fire. 

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6 hours ago, 671jungle said:

I would apply a choke to determine where max intake air intake is without making the flame “too lean and weak”. This mark is the max opening of the next build.

This is not the case in Trevor's burner, but in general, if your flame is too lean, your orifice could be enlarged.  By choking off air to match fuel requirements, you are reducing your burner output.  By increasing your orifice size instead, you are increasing it's output.  

However, if you can partially choke off your air inlets and see no change, then you might start looking at smaller inlets.  Which I am guessing is what you were actually meaning?

Just to add to the fun, in a few cases, I have decreased the size of the air inlets and that resulted in an increase in air induction.  :blink:  I don't understand most of it so this usually gets me excited and I have to start playing with smoke streams to see what is going on in there.

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3 hours ago, 671jungle said:

I’ve always said at bbqs, campfires and full moon parties:ph34r: that there is a science to building a fire. 

That's a guruism if I ever heard one.

Frosty The Lucky.

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10 hours ago, Another FrankenBurner said:

However, if you can partially choke off your air inlets and see no change, then you might start looking at smaller inlets.  Which I am guessing is what you were actually meaning?

Yes, thank you Frankenburner. Sometime i get caught up in thought arrangement.
About your smoke stream tests: is it possible that specific inlet shapes coupled with specific nozzle shapes can create a combustion strong enough to compress air into the mixtube?

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I am not sure I fully understand the question.  If I did, there is a good chance I have no idea at the answer.  

When I decrease the inlet size and this results in increased induction, I suspect it is because the air is entering from a lower angle which contributes to vortical flow.  The vortical flow, lowering the pressure, is more efficient at drawing in air and moving it along.  

The addition of the aerospike made this more obvious.  (thank you for the term Frosty)  With that addition and balanced inlet size, I can clearly see 3 separate vortices which gang up at the point where the jet meets the throat.  At that point, there is a very tight vortex which immediately heads down the mix tube.  This significantly increased air induction.

In this post is a very poorly shot video which shows what I described.

 

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On 3/23/2020 at 7:48 AM, 671jungle said:

is it possible that specific inlet shapes coupled with specific nozzle shapes can create a combustion strong enough to compress air into the mixtube?

Yes to the basic concept, and a resounding NO to the idea of "compressing" air into the burner.  We speak of inducing air into the burner via Bernoulli's principle; the gas jet providing our "motor." we speak of streamlining, and using vortex principles, creating a low pressure area in the flame retention nozzle; all in various attempts to "massage" the flow of an air fuel mixture into, through, and out of the burner. 

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Ditto, "Resounding NO." Induction devices work by lowing the pressure of everything down stream of the intake.  Naturally Aspirated means it's nature is to inhale. Aspire means to "Breath In"  Espiritus is to take or breath in the Spirit, Live. Just as Expire is to breath out your last, exhale your Spirit. Feeling inspired is to breath in the spirit of an idea. 

Enough Frosty side tracking. A naturally aspirated burner or any induction device stops working at all if it' internal pressure reaches ambient. A soda straw can't work if the pressure is equal at both ends. 

Frosty The Lucky.

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If we are talking about ambient pressure compressing air into the inspirator than I have to fall in line with the answer of nope.  They work the opposite of that.  I wasn't sure if that is what was asked or if compression within the mix tube was the subject.  Thinking of the latter has entertained me.  I need to play with the manometer a bit more.

My mind is running circles with the idea of the mix tube being lower pressure than ambient at the flame end.  How is it discharging if the pressure is lower than ambient?  

The soda straw analogy demonstrates pressure differential very well but with an inspirator, the low pressure zone is upstream of the delivery end.  After which, we are moving to a push, I think.  When I was playing with a venturi and manometer, I saw a pressure increase after the throat.  Compression.  I don't remember what that pressure was compared to ambient but I suspect it was greater as the device has to push against ambient or, worse, forge backpressure.  

Now that I have talked myself into overthought confusion again, any takers?  

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Okay, let's flip to the other side of the coin, by thinking back toward the beginning of the process (air induction into the burner), from the end of the process: the flame.

It's always all about the flame(s).

The harder/faster/bigger the flame is the greater its explosive potential; and with that, it's tendency to blow itself off of the burner's ignition zone; snuffing itself out.

The only counter-force holding the flame on the burner is the ambient air pressure it is pushing against, to make its getaway; which is negligible--unless there is a low grade vacuum (AKA low pressure area) in the flame nozzle to "glue the flame in place." 

The lower the  mixture pressure within the flame retention nozzle, the stronger the "glue>" Also, the lower flow pressure is in the nozzle the greater its contribution to air induction at the burner entrance.

BUT, the flame retention nozzle's low pressure area also serves to prevent flashback into the burner's mixing tube, were it could continue completely through the burner. The mixing tube itself serves best if its overall flow pressure is very low, because the higher pressure of the gas/air mixture into the mixing tube the higher the final pressure in the flame retention nozzle.

So, coming now to the beginning. The greater air induction is into the burner, MINUS INCREASED AIR PRESSURE the better. Since air induction can be encouraged in a number of ways (ex. streamlining), but any increase in internal pressures are extremely hard to erase...

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Oh boy I missed a bunch while I was away. 671Jungle, that's a beautiful flame nice stable shape. 

Hey Mike I already had two burner Tubes made up so I would be able to try different lengths after the air slots. For some reason I can't get a decent flame burning outside the forge, I'm trying to use a step nozzle and have put it together in several configurations but I either run rich with the orange flame or I blow the flame out. 

I cleaned up the air slots, trimmed the mixing tube to 8" after the air slots, 0.023 contact tip. Inside the forge I can get these flames. I get no dragons breathe once I get the forge up into the yellow range and yellow is easy to hit and hold. Im not sure what you see in these flames but they seem to be working fairly well. 

To hold a yellow temp with my old burner running a 0.035 tip I would run about 10psi. This burner running a 0.023 I run about 10psi for the se yellow temp. Am I correct in assuming that I am using less fuel but getting more heat because I'm getting a more efficient burn? 

Here's a couple flame pics and a pair of tongs this new burner helped make. 

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20200325_171027.jpg

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7 hours ago, Another FrankenBurner said:

My mind is running circles with the idea of the mix tube being lower pressure than ambient at the flame end.  How is it discharging if the pressure is lower than ambient?

Ahh, I've been waiting for this perfectly reasonable intuitively obvious question. Thank you AFB! :)

Pressure is NOT what's pushing the mixture out of the mixing tube it's momentum. The inertia of the primary (gas jet) is drawing air with it and as it expands to fill the mixing tube the pressure decreases but it's velocity only lowers slightly so the same fuel is taking up a larger volume and moving fast. About the time the primary jet encounters the inside of the tube and builds it's boundary layer it's slowed as much as it will not counting friction. 

A conical flame "retention" nozzle (I'll explain the quotes in a bit.) further enlarges the volume the mix has to fill causing the pressure to drop more increasing induction forces up stream, momentum again. What makes flame retention nozzles work to hold the flame on the nozzle is the sharp pressure increase of explosive combustion. There is a sudden drastic increase in pressure right at the end of the nozzle and because some of the mixture's velocity and momentum has been absorbed by expanding into a larger volume the flame front stops where it ignites.

About the quote marks around "Retention" To retain is to hold, the term was adopted to mollify folks feuding about whether the cone increased induction or held the flame. So folks who'd argue if you called it a flame Holder and the other side who'd say I TOLD YOU SO! Started listening instead. The cone does both, a win win what's to argue with that?

Anyway, that's a typically long winded Frosty explanation of why higher than ambient pressure at the burner mouth is overcome by a lower pressure fuel air mix. Velocity = mass, pressure = density. It's easy to confuse the two I had it explained more than once over coffee.

 Trevor: It's hotter because your fuel air ratio is closer to neutral and so more efficient. So yes, it's using less fuel for the heat. 

Frosty The Lucky.

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