Mikey98118

Burners 101

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Good stuff guys. There is how-to knowledge, and design principle knowledge, and then there is my favorite; which is just perspectives gained over time. Somehow, personal stories seem to get through to people better than the other kind of facts can :)

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Another tip for those that have the large tanks that the propane supplier fills on site (like ours). Have them put some methanol in when filling about twice a year. I found out about this from my supplier when we were having problems with the gas furnace. Seems too much moisture will accumulate due to condensation in the spring and fall. The methanol eliminates that moisture but you have to ask for it.

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Another Curtis:  out of curiosity, is R-290 pure propane or is it LPG, like we get for running forges/bbq's etc. I know they are virtually identical but my understanding is the LPG fuel differs in some ways compared to pure propane.

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Some think LPG stands for liquid propane gas but it stands for liquified petroleum gas.   It is a mix as you stated.  Usually containing propane and butane as the main components and some others like propylene make up a small percent.  There is also an odorant added so leaks can be detected by smell.  The mix has to meet some guidelines but it can be different from batch to batch.  Depending on time of year, the propane/butane ratios change.    All of this is what the propane guys told me.

R-290 is refrigerant grade pure propane(99.5%).  A mix would have a different pressure/temperature relationship which would change the requirements of the system using the refrigerant, so it is important that it is always the same.

I wouldn't pursue it as a fuel though.  There might even be laws against as it is not odorized, but I'm not certain.

 

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No problem on the info, it was all free to me.  I didn't suspect you were aiming to use it as a fuel but I figured I better say it, just in case.  R-290 is starting to be used again because it is not a fluorocarbon so it does not deplete the ozone.  Good for the fridge and the forge and the planet, I guess.

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On 12/21/2018 at 9:06 PM, AnotherCurtis said:

yellow oily smelly liquid

Mercaptan oil IS the odorant in propane and is the source of most of the waxy gunk I've found blocking jets. In AK. we don't usually get low proof propane, it costs too much to ship up to get a bad rep or have to buy it back. Can't say about Blue Rhino though. 

If you don't like the smell in old tanks add a cup of chlorine bleach and fill with water an overnight soak will deodorize the tank.

Frosty The Lucky.

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Mr.  Dragon,

Great point about adding methanol to the gas. 

Adding methanol to the gas, (propane, butane, etc.), is an excellent idea to get rid of condensed water vapor,  which will sit at the bottom of the gas cylinder, potentially corroding the gas cylinder. 

But one note of caution about using methanol.  Keep the liquid far away from your eyes.

Methanol can trash the optic nerve of our eyes. Blindness results from that. That includes it's vapor.

It is also poisonous, when ingested. (drunk)

Other names for methanol are,  methyl alcohol, methyl hydrate, and wood alcohol, etc. It's all the same stuff.

I strongly suspect that anhydrous ethanol will do the same job.

(ethanol is also called ethyl alcohol, drinkable alcohol, etc.).

Denatured means that the manufacturer has added a small amount of an adulterant to make it undrinkable. 

The liquid water goes into a solution with the alcohol. That solution has a much lower boiling temperature (with a  lower vapor pressure).

So the mix, readily, forms a gas with the 'propane' and is burned off.

Merry Christmas,

To all the iron bangers, (& also lurkers / guests)  on this site.

SLAG.

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Hi Brothers: I've been having a few problems with my forge and tried some advice from this site to no avail. My tank is almost empty now and I know its a old tank that sat for several years. I was thinking of running a natural gas line to my shop instead of using propane. I haven' t heard much about natural gas forges so not sure if it will solve any of the problems or just create more. Whats your opinion on the switch. Thanks.

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You will likely need to build a fan-blown burner to run it; they aren't easier or harder to make properly than Naturally aspirated burners.

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I would advise against the natural gas as a remedy for a poorly functioning propane forge.  Fix the forge instead or first.  Natural gas is typically plumbed in low pressures which will not be plug and play with your current poorly functioning forge.  Natural gas also contains half the energy per volume of propane.  While low pressure natural gas is doable, it is almost an apples and oranges kind of thing when it comes to burners.  Entirely different requirements of the burner system meaning different designs.  

I recommend going to the Forges 101 thread and posting your exact situation with the poorly functioning propane forge so that people can give you their advise.  Currently we know nothing about what is wrong with your propane forge.

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Safety in fuel/air torches

Recently,  I have been seeing MAP gas hand torches online; these are so called dual-use torches, which are rated to burn propylene as well as propane). Some air/fuel torches now come with a short fuel hose, instead of just being mounted one 1 lb. cylinders. Separating the torch from its fuel cylinder allows it to be easily positioned at any angle, while the cylinder, which must remain upright, can do so unhindered; but its value when mounted on a forge or casting furnace is that the fuel cylinder can be kept a few feet away from the hot equipment.

the latest versions of air/fuel torches also feature two needle valves. One valve is part of the cylinder fitting, while the other valve is mounted on the torch head. You may wonder why two valves? The answer is safety. With a separate valve at the fuel cylinder, the hose and torch can be exhausted of positive pressure after shutdown, while a second valve on the torch can then be closed, preventing ambient air from mingling with fuel gas in the hose. Without positive pressure, even a needle valve is unlikely to leak, and pure fuel in the gas hose is no more flammable than air is. We might think that simply detaching the assembly from the fuel cylinder will do the same job, but the reason that 1 lb. fuel cylinders are not supposed to be refilled is that, once opened, their valves are no longer reliable; they can leak.

The whole point of discussing air/fuel torches on the Burners 101 thread is that they can be used, with or without some modification, as a practical substitute for 1/4" burners, which can be built, but would cost more than these torches, to do the same job; that job would be running two-brick and coffee-can forges; at $30 they are a bargain.  

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BTW, the self igniting option on air/fuel torches doesn't usually work very long. The piezo eclectic crystal is durable, but the wire can fail in short order. What happens is that for a split second during ignition there is some blast force generated on the heating wire end; this gradually straightens the wire enough to prevent the spark from jumping the gap between wire and the burner (which provides a ground). You can push the wire back into position two or three times, and then it breaks off.

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So, I was going back over what made my burners so hot for the second time, and getting frustrated, when the guy asked "is it because it tunes better?" Well of course they tune better!!! That's go obvious, but... And there it is again; the obvious. Yes, the better a burner's flame can be tuned the more it can be refined, and therefore the closer it can be made to perfect; that means ANY Burner. We work with guys on tuning problem burners all the time here on IFI. Some times they need to adjust their parts so that the burner can be better tuned. Other times they simply have no clue how to tune their burners.

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Chokes

 

air induction on naturally aspirated burners tend to increase and decrease apace with gas pressure. If a burner needs choking to keep the flame from becoming lean (oxidizing) than the gas orifice needs to be enlarged. The choke on a well designed burner should only be used, when a reducing flame (fuel rich) is desired during welding, and after shutdown; to prevent chimney effect from overheating burner parts.

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To zinc of not to zinc

The boiling point of zinc (the temperature at which it can make fumes) is 1670 F. So zinc coated flame retention nozzles or mixing tubes are out. There is no reason at all to avoid zinc coated reducer fittings.

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Flame retention  nozzle balance

Every part of a burner contributes or subtracts from the balance of its air and fuel gas flow. In turn that that flow must be balanced against the flame's tendency to depart from the burner's end, by the difference between the push of atmospheric pressure against the low pressure area provided by the flame retention nozzle. Fortunately the whole process automatically interreacts to a large extent, so that the balance isn't all that hard to maintain. However, the better all these factors are balanced against each other, in the design of a burner's parts, the harder a flame the burner can run.

The primary function of a flame retention nozzle is laid out in its name, but the secondary function is almost as important; to help induce air into the burner. The amount of air a flame retention nozzle an induce varies according to how radical its design is. A moderate taper will induce less air than a arger amount of taper, which will induce about the same amount as a stepped taper. But there is a second factor with slid-over nozzles; they can change the proportion of their length to width ratios, which will also change the amount of air induction. The advantage to a sliding stepped nozzle is that the amount of change will be greater than that of a tapered nozzle. The advantage to a tapered nozzle is that it will work properly on a greater range of burner designs than a stepped nozzle can.

If nothing else comes to mind, this should make obvious that the additional work to employ a slide-over nozzle, rather than a screwed on reducer fitting will always be well worthwhile :)

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The limits of chokes

One of the "circumstances" that have "altered cases"  over the years is the general improvement in naturally aspirated burners. Once upon a time there were two very good reasons for adding chokes on burners; the first being to prevent chimney effects after shutdown, and the second being to very flame characteristics. As N.A. burners have grown stronger, the chokes ability to alter their flames has diminished somewhat; the technique still works, but is perhaps not so obvious. I would regard it as still present, but far less fun to play with.

Burner chokes still greatly diminish chimney effects after shutdown, but require a secondary control mechanism (such as a washer on the burner's mixing tube), to completely stop it, and always did. What was important about including a burner choke, was that it greatly reduced a rise in burner temperature after shutdown, protecting gas assembly parts from overheating. But protection of vulnerable hoses always needed the addition of control of secondary air through the space between burner and burner portal after shutdown too.

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I have been playing with inducing vortex down the mix tube.  I have also been experimenting with inlet shapes to accommodate lower velocities.   

Here is my latest toy.   The throat of this burner is 3/8 pipe ID (0.493 in) and the jet is .031 actual.

1216895354_3_8burner1-6-19.thumb.jpg.988c8a3db7d764d4a797485feb84db3f.jpg

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I am assuming that you are using a reducer or cone shape of some sort on a linear burner in place of side air openings? First, let me congratulate you once again. I consider using an orifice of .031" on a 3/8" burner size (thus allowing guys to employ a standard MIG contact tip), and still produce a flame that hot to be a MAJOR feat!!!

You is in danger of becoming the new Dr. Frankenburner. Now give us all the details :D

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2 minutes ago, Mikey98118 said:

Now give us all the details :D

Yes, please do!!

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Thank you for the accolades again.  They are encouraging.  Though in this case, I shouldn't be getting credit for a 3/8 burner size.  I used the same diameter as 3/8 pipe for the throat arbitrarily.  This burner is sort of a cobbled monster so perhaps the mad scientist reference is applicable.  I take it as a compliment. 

This burner is a partial wasp waist burner with a section of pipe after it and a nozzle.  The inlet is a trumpet shape with about a 1.25 diameter down to the 0.493 throat.  The outlet is an immediate 1:12 taper out of the throat for about 1.5 in to a diameter of 0.622 which is the ID of 1/2 pipe.  Then a small section of 1/2 pipe to a 1:12 tapered nozzle.  An 0.023 mig tip drilled out to 0.032.  I misspoke with the 0.031.  The ribs which run to the accelerator block are airfoil shaped to encourage spin which can be visibly watched in the secondary flame.   If you look at the image I posted above, you can see evidence of it.  Though I am not sure if the ribs add anything to the spin or if the reducer is doing the work.  I will make one with straight ribs to see if spin still exists and to see what else changes. 

1746817026_Burner3.2.jpg.74889ab8a692cd24e439c40e838888d6.jpg

Half wasp waist burner, half straight tube.  Not quite a 3/8 burner, not quite a 1/2 burner.  With the mig tip size and pressure used, it puts it more in the realm of 1/2 burner btu output.  An experiment into lower velocities inducing enough air.  With the 0.023 mig tip unmodified, it induces enough air to run at lower pressures which was my goal.  I wanted a "low" output burner for a coffee can forge.  At higher velocities, it induces way too much air.  I drilled out the jet to see what the high end output could get to which was the image I posted. 

Here is an image of the low output.  It was when it first started so the nozzle was still cold.  Sorry it is blurry.  The flame is fairly laminar because the 1/2 inch pipe section is long.  It is also sucked back into the nozzle as the velocity is low.

Flame.jpg.5ff9103e3a9a5a7b9021a0771803dd84.jpg

My next low velocity experiment will be to get the largest mig tip running the lowest pressure I can into the smallest throat possible.  Just to learn the relationships of the shapes.

After that my next direction for experiments will go in the high velocity motive fluid direction and experimenting with mix tube length vs outlet nozzles size/shape.  My thinking is that higher velocities have more energy to do more work and I will experiment with slowing the whole train down at the business end.  Eventually leading to into NARB territory once I have a few different inducer designs to play with. 

I will take what I learn from all of that and move into 3/8 burners.  

I enjoy the spectrum of high velocity vs low velocity.  Both have merit and high/low points.  I am finding that balance is the key to every burner and all of their geometries.  At low velocities, the difficulties are inducing enough air, mixing it properly and preventing flame suck back.  At high velocities, the difficulties are regulating too much air, preventing flame lifting, and blowing all the btu's right out the door.  I have also found that a balance can be found in most burners so they are stable but some have much better range then others.

I am up for any discussion, questions, criticisms, ideas.  I am just having fun over here.

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Oh MY another Frankenburner indeed! Nice looking flames all Curtis, well done. The drawing is good but where are the pic of the burners themselves? I'd like to see how you made the intake flare. 

Any flared intake will induce a vortex, it must, conservation of angular momentum says so. The shape of the intake has a lot to do with how strong it is. A bell reducer is better than nothing though far from ideal. A straight cone intake is much better. The "trumpet"(for lack of a better term) is the better. Take a look at ANY air intake and you'll see an air foil shape like a trumpet but oriented a little differently.

Correct, power in = power out less entropy. Friction being the entropic factor that's why curved surfaces are so beneficial. Curving them in the correct direction is primo! For instance a bell reducer cause the intake air to turn towards the mixing tube by making it collide with the reducer walls. It rotates because it must unfortunately the change in size of the vortex is by brute force. Where a trumpet shaped intake causes the vortex to shrink as it nears the throat via low pressure, just like flowing over an air foil. Airplane wing in profile. The air flowing over the top has to travel farther than the air flowing past the flat part of the wing. The air above produces a much stronger vacuum boundary layer so the high pressure under the wing supports it.

A cone only has an inside curve though much better than the inverted compound curve of the Bell reducer. A cone's vortex speed and effect increase is more linear than a trumpet flare.

I don't know if there are features you can add to an intake flare to increase the vortex though I've thought about it a lot. The vortex is going to happen and without Mike's use of a fan blade I don't know how to improve it. The problem with influencing an intake flow is not being able to effect it until you can physically "touch" it. If you set up an induction device in a water tank  you can add drops of food coloring and watch how things move. The dye flows straight to the intake and doesn't begin to move in a vortex until it contacts the existant vortex. This is before it "touches" the flare but not much.

I really  miss my old aquarium. <sigh>

Frosty The Lucky.

 

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