Burner?!?

[dps9999]

Hey everyone i am new to this forum but i thought it would be a place to get a lil help. Just so every one knows...I have a small forge now (not tiny but not huge the inner dimensions are 10in deep by about 6in diameter.) this is inside the inswool and coatings. I also have a venturi style burner very similar to the one here 

Now i was thinking is it possible to turn this into a forced air burner by simple making a attachment that could fit into the hole you see on the side (where normally the air would get sucked in from the venturi effect) and basically have a tube run from the side there into a blower with a gate valve in between. Would that work? or better keeping as is and building a separate blown burner?.

[Charles R. Stevens]

Might I ask why you want to convert a servicable forge burner to one that requires a electrical sorce? 

[Frozenforge]

If that is a 3/4" burner you should have no problem using it the way it is in that size forge. The venturi burner will be more sensitive to forge design and propane pressure settings. The forced air will need a way to regulate the air supply and propane pressure.

Do a little research and you will figure it all out!

[ThomasPowers]

This is sort of like "Hey how do I modify my car's gas engine to use diesel?"  Better and easier to make one designed for the blown system from the git go.

[Frosty]

Why do you think a gun burner works better than a naturally aspirated burner?

Stick with what you have till you know how it works. For instance the "Venturi" affect has nothing to do with a naturally aspirated burner, just the opposite in fact. A NA burner is an induction device using a high pressure primary fluid (gas) to induce a vacuum that draws a secondary fluid (gas). Two whole different things. both are described in Burnoulli's fluid laws.

Google "Venturi." or better yet Venturi Tube.

Please don't start experimenting with devices that use explosives without knowing how they work. Not that you would be the first person to play these kinds of games and I don't wish you to join the ones who burned themselves out of a home, or injured themselves, others or worst of all killed someone.

Frosty The Lucky.

[dps9999]

thanks guys for all the advice!... lets see if i can answer  everything   first....i have been using this "na" style burner but have wanted a blown burner also i have been doing alot of reading and watchin video's of how they work and the only differences than doing what i asked about is usually the air comes from behind the gas not the side as it would with this plan. Also the tubes are usually 1 inch at the flame end instead of 3/4. From what i have read the blown style uses less propane and can usually get hotter. What i was thinking if i did what i was asking about maybe i could have the best of both worlds where as if i screwed in a attachment and a tube from a blower in the side it would act as a blown burner but if i unscrewed that tube and attachment it would go back to working like a NA burner. Ok lastly i admit i dont know EVERYTHING about these burners but i do understand how the NA works, I built the one i have pritty much exactly the same as pic above. It works great not saying it doesnt i was planing on building a blown burner from scratch but figured lets find out if a 2in1 type thing is possible. i understand the high pressure gas is what sucks the air in. I guess i was just using the wrong name but you have to admit ALOT of people call these "venturi burners". I understand enough how to make a blown burner from scratch. I was curious if any one has done what i was talking about meaning the air from the side instead of the back and the size of the pipes as stated above. Guess ill have to just go back to original plan and make a separate burner seems to be the right way to do it.

[ThomasPowers]

For a properly tuned forge: how hot the forge gets is totally a function of how much propane is burnt.  Your comment on one getting hotter than the other  sounds like you saying it takes less water to fill a quart jar from a hose than from a faucet.  The small orifice for an aspirated blower is used with higher pressure propane to get the jet needed to pull in the air and mix it.  Blown burners often have larger orifices and work at lower pressures HOWEVER the heat generated is totally based on how much propane is burnt so for the same number of BTUs going into the forge the same amount of propane is going into the forge whether it's a big orifice and low pressureor a small orifice and high pressure.

[Latticino]

Air from the side will be effective, though the abrupt elbow it takes will make it less effective than if it entered the "typical" forced draft burner fashion, due to the pressure loss associated with the rapid change in direction of air.  If your blower pushes enough static to overcome this, it should be fine.  You may want to replace your gas nozzle with a larger one to take advantage of the increased output your new burner can be capable of.  I believe that it is a misconception that a blown burner is intrinsically more gas efficient than a comparable naturally aspirated burner.  However, with the same gas pressure of propane available, and the ability to replace a gas nozzle so that more gas is available at that pressure, you can almost always get more heat from the blown burner.  You also get a bit of grace on the size of the forge doors and the outlet of the burner itself, as the burner pushes the flame out at increased overall pressure.

You also need to know how to properly tune and operate this type of burner.  It isn't all that hard, actually a bit easier than a NA burner as far as I'm concerned, but it is different.

 

Cross post with Thomas.  Totally agree with all he has said, but as I noted, with the same high pressure propane (typically modulated down a bit using your regulator) and a blower, the burner will be capable of burning hotter (especially if you increase the nozzle size at the same time).

Edited October 12, 2015 by latticino

[Frozenforge]

I have not operated a blown style burner myself but it seems they can run in a forge with smaller exhaust openings, I would imagine that would reduce the heat loss a little. 

[Frosty]

DPS. The temperature available in a forge is directly related to how much fuel and oxy can be burned per second PERIOD. A gun burner can NOT be more economical AND be hotter. That's like saying something can be lighter and weigh more. Contradiction in terms.

An advantage of a gun burner is the ability to more thoroughly mix the fuel and air. Propane doesn't mix well with air, unless you actively stir it it will separate quickly. Being able to force the mix around a corner will induce turbulence that will enhance mixing. Unfortunately feeding the forced air in the side and propane from the end is backwards and doesn't really help much.

One of the other advantages is the blower's ability to overcome back pressure more easily.

DPS. If you already know how to build both types build one of each. A tool that does everything, does NOTHING WELL.

Max air fuel mixing is achieved in a gun burner by introducing the gas at the blower intake and letting the impeller mix them. Then part way to the forge chamber turn the pipe 90*.

Frosty The Lucky.

[BANAN]

The advantage of naturally aspirated burner is that it does not need power.  Burners operating with fans have the advantages of a lot more. I will mention here less gas consumption, adjustable flame atmosphere, the opportunity to work with a heating recuperative air supplied to the burner, absolutely safe operation without rolling back the flame to the burner.
Such an image as the photograph is very common in my forge, sometimes it can not keep up with the production of burners. Demand for cooperating with ventilator burners is very high. None of the blacksmiths who once worked on the burners naturally aspirated, does not want to return to them.

[ThomasPowers]

I guess none of them ever work several miles away from a power outlet!

[BANAN]

The first five burners in the first photograph, can run 5 miles from the socket

[ThomasPowers]

Take a look at the data on where we live; New Mexico has about 2 million people in 315194 sq km; Poland has 38 million in 312700 sq km;  lots more places with no power out here! (I take a forge camping as often as I can and due to the desert conditions many places require propane devices only.)

[timgunn1962]

On 11/10/2015, 15:31:48, dps9999 said:

 

Now i was thinking is it possible to turn this into a forced air burner by simple making a attachment that could fit into the hole you see on the side (where normally the air would get sucked in from the venturi effect) and basically have a tube run from the side there into a blower with a gate valve in between. Would that work? or better keeping as is and building a separate blown burner?.

Tentatively yes and definitely yes: It certainly could work (note this is not the same as will work). It would be better to build a separate blown burner.

The Naturally Aspirated burner uses the gas velocity to draw in air. If you need more air, you can simply go to a smaller gas jet and run at higher pressure to keep the same gas flow. In most cases, this will give a higher flame temperature because most burners run rich. You can then fit a choke to restrict the airflow when you want to run richer and at a lower flame temperature. 

If you want a blown burner as well, build one to a known good design. Avail yourself of the time and effort someone else has put into the design process and spend your own time and effort forging stuff. Unless of course you want a new hobby and feel burner development would be a good one.

 

[ThomasPowers]

Isn't that backwards?  The aspirated burners are very picky on getting things set up just right---use a documented working design and follow it *closely*; (and most tend to burn lean) But the blown burners you can basically dump propane into the airstream and easily adjust air and gas to get the best burn---or the atmosphere you want, I do blades and so often like reducing .  I've got both types and have been using them for 15+ years so far.  I've seen a blown burner that was just a 1/4" copper pipe dumping natural gas into the airstream of a 1960's hair dryer ---used to teach a class on brass casting at the University...

[timgunn1962]

You are absolutely right Thomas: starting from scratch, a blown burner is very simple. There are lots of nice ones out there that work very well and are easy to copy well enough to get the performance required.

Making a NA burner that works even moderately well does need either a lot of luck, a good understanding of the process, or a good set of plans built quite meticulously. Preferably all 3. It is indeed much harder than making a blown burner. 

I'd read post #6 above by the OP about hybridizing the burner to get extra air in (presumably for higher temperatures), whilst retaining the facility to run as a NA burner. It seemed to place unnecessary constraints on the design of a blown burner.

Thinking about it, I'm pretty sure I could make such a system work pretty well. However, I never would because I could get a similar effect with higher gas pressure, a smaller jet and a choke for less money and less effort. 

I don't think I've actually seen many NA burners running lean (some certainly, but not most). The majority have had Dragons Breath, indicating a rich (reducing) forge atmosphere. That said, I tend to see bladesmithing forges, rather than blacksmithing forges.

 

[ThomasPowers]

Adding a choke of some sort to a NA burner seems to be common to control atmosphere---even just duct tape across the bell for that type.Mine has a plate that screws closer or farther away.

[Mikey98118]

On 10/11/2015, 3:59:57, Frosty said:

Why do you think a gun burner works better than a naturally aspirated burner?

Stick with what you have till you know how it works. For instance the "Venturi" affect has nothing to do with a naturally aspirated burner, just the opposite in fact. A NA burner is an induction device using a high pressure primary fluid (gas) to induce a vacuum that draws a secondary fluid (gas). Two whole different things. both are described in Burnoulli's fluid laws.

Google "Venturi." or better yet Venturi Tube.

Please don't start experimenting with devices that use explosives without knowing how they work. Not that you would be the first person to play these kinds of games and I don't wish you to join the ones who burned themselves out of a home, or injured themselves, others or worst of all killed someone.

Frosty The Lucky.

Hi Frosty,

I like what you said about "venturi" burners. I gave up trying to point out the flaw early on, but it is quite confusing for people who start out by trying to look up venturi  systems, instead of Bernoulli's Principle. Bottom line is that the constricting shape past which the air is being induced by the fuel gas has everything to do with spinning the gas and air for proper mixing, and nothing whatever to due with venturi systems. All successful NA burners spin the fuel gas and air, whether by using a funnel shape at the air opening of a linear burner, a single side opening (side-arm and modified side-arm burners) or multiple side openings (Mikey burners)

Mikey

[Mikey98118]

After inventing, perfecting, and writing about gas heating equipment for the last sixteen years. I can tell you all from personal experience that the ongoing debate on powered versus naturally aspirated burners is just wrong headed. The best any of us can do is observe and learn about the equipment he/she actually uses. I've yet to see anyone from one camp deliberately investigate the equipment beloved by the other. Here, I'm suggesting an open minded evaluation that might take years; not a few months of dissatisfaction with a particular piece of equipment that was probably a poorly designed and/or constructed product in the first place; for who abandons a forge or burner because of over satisfaction with it? unless burner design, rather than forging, is your main passion how will you find time for such an effort? Without walking this path, your only reasonable hope if gaining sufficient knowledge into equipment you don't have (let alone use) is to ask about it from those who do; so how much even handedness is it reasonable to expect from those you insult?

BTW, burners and heating equipment just happens to be my passion, yet I've only begun to investigate powered burners. Frosty happens to be right about "no free lunch" with fan-blown burners; they tend to put out more heat overall during a given time span, but that either comes at the cost of more fuel expended or of lower maximum temperature in the equipment; in either case "hang time" for any given combustion product is reduced. So if you're looking for shorter heating cycles go fan-blown; If you're looking for fuel efficiency, forget it. One other thing that only fan-blown burners do well is power chip forges, for any naturally aspirated burner capable of providing sufficient heat to the chip holding area, will overheat the firing chamber below it; the reason for this limitation is compact high temperature flames. Fan-blown burners can produce much larger lower temperature flames.

Production is critically important to people making a living, just as keeping costs low and shop areas cool is to most hobbyists. However, a successful hobbyist is likely as not to find him/her self drifting over to the professional side, so keeping an open mind is kind of important.

Mikey

 

On 10/11/2015, 6:45:40, ThomasPowers said:

For a properly tuned forge: how hot the forge gets is totally a function of how much propane is burnt.  Your comment on one getting hotter than the other  sounds like you saying it takes less water to fill a quart jar from a hose than from a faucet.  The small orifice for an aspirated blower is used with higher pressure propane to get the jet needed to pull in the air and mix it.  Blown burners often have larger orifices and work at lower pressures HOWEVER the heat generated is totally based on how much propane is burnt so for the same number of BTUs going into the forge the same amount of propane is going into the forge whether it's a big orifice and low pressureor a small orifice and high pressure.

 

[Mikey98118]

Thomas,

Generally speaking, you are correct. But, but the longer "hang time" from smaller hotter flames must also be taken into account, making you even more correct than you thought :-)

But, the high production rates from fan-blown forges cannot be denied...

I had to put aside my own preferences-turned-prejudices, and start investigating powered burner systems to come up with a truly updated burner design; it's called a Vortex burner, and uses both induction and fan power. Vortex burners are power boosted NA burners that can operate in either mode, because they definitely are not fan BLOWN burners. Their very weak impeller fans, can run on highly portable 12V batteries for hours at a time because their power is used to boost the action of a vortex in a constricted area (funnel shape), rather than to blow more air into a burner. What they do blow is every previous NA burner design (including all of mine) "off the road." But are they the ultimate perfect burner? NO; there just ain't no such animal!!! Even the most wonderful of burners is just another burner, and the very virtues that make it outstanding for some jobs will reduce its utility for others. After I finish playing with this design, it's back to the old grind investigating fan-blown burners, which still due some tasks too well to be ignored (darn it).

Mikey

[Charles R. Stevens]

My interest at this point is in NG burners, particularly as my gas company is very open to instaling high presure taps. Less so with blown NG burners

[Frosty]

MIke: How long you been lurking?  And no, I haven't done anything to significantly improve the T burner except to come up with a simple jig so folk without good shop skills can drill and tap a properly aligned hole for the jet.

How long have you been messing with vortices in the burner? I've kicked the idea around for some time but it has to take place with some of the many ideas I kick around.

I did a couple simple experiments and determined a vortex in the tube can't improve induction but will increase the time the fuel air is in the tube. By it's nature I don't think just prolonging the time propane and air has to mix in the tube really helps much. All States torches have a perforated swirl strip in the mixing tube, Lyle said it was the only way to thoroughly mix propane and any oxidizer. And yes he experimented with vorticies. that was just conversation on the phone when he was trying to talk me into handling online sales but I had a paycheck job that kept me in a tent most of the time. It would've been a poor side job and bad for him. Anyway, he had to use a forced mixing system to get his torches to work better than a Victor conversion tip.

I think I'd rather mess with cavitation as a standing shock wave to induce mixing. The air fuel would spend much less time in the tube and if done right it'd act as a flame holder that didn't inhibit flow. A significant draw back would be the sound, sort of like a never ending super sonic bullet crack.

Hmmmm?

Really good seeing you in writing again.

Frosty The Lucky.

[Mikey98118]

Hi, Frosty.

I'd been overheated with writing books on so many subjects, and just spent less and less time writing on groups. But recently a hacker destroyed three of my books (no back up copies; my bad), and I decided to set a saner pace. Four years back I started to research and write a general work on fan-blown systems. Two years ago I tried using an impeller style axial computer fan at the funnel entrance to power a linear NA burner (wanted to review linear burners anyway, as my early success with jet-ejectors pulled me away from them sooner than I liked). The result was so powerful that I've concentrated on Vortex burners every since. After the initial Eureka moment, I went back and started reading up on vortices, since I could find no other phenomena to explain the mind blowiing performance increase. Wow, just read a little bit on the laws of vortical flow, and you'll soon wonder how we  could have missed the opportunities it presents all these years; its like the magic answer to every builder's problems and limitations in burner construction.

For instance pushing air through a funnel will create spin, which is so necessary for proper air/gas mixing, but it also increases mixture pressure in the mixing tube a little further on. This is added to the increased pressure that the fuel gas stream causes while inducing air into the tube. The total pressure increase has a very bad effect in the flame nozzle, severely limiting nozzle vacuum, and therefore limiting flame performance.

But take a fraction of that fan power and use it to directly increase vortical flow, instead of as a by-product of pushing air, and incoming air feed rate increases, along with spin rate, WHILE PRESSURE IN THE MIXING TUBE DROPS. Thus, at the same time mixture feed is being greatly increased, flame nozzle pressure is greatly decreased, allowing a given nozzle diameter to hold a much larger and faster flame in place. Since mixing is so much more thorough the flames are less turbulent, and therefore the jet engine roar of flame noise also drops. A win, win, win situation.

Would you like a general discussion on this subject?

[Mikey98118]

Charles says "My interest at this point is in NG burners, particularly as my gas company is very open to installing high pressure taps. Less so with blown NG burners."

I'm afraid you're do for considerable disappointment if you want to use natural gas in a naturally aspirated burner. The commonly accepted idea is that NG is only used in fan-blown forges because most people are stuck with an ultra low-pressure gas service. This 'fact' is only partially true, and very misleading. One art school I attended had high pressure NG available, but only used it in two large NA annealing torches for their jewelry classes; their bronze casting furnaces, day tanks, and glory holes were all fan-blown.

The reason for this is simple; methane burns with about one-half the heating ability of any other LPG fuel. Methane uses less oxygen, and therefore less air than any other hydrocarbon fuel except acetylene, and its primary flame temperature is rated only a little below propane, so you'd think it would be a hot burning fuel. But there are two facts about methane combustion most people don't know. In the first place about 80% of methane is consumed in the secondary flame---not the primary.  But even worse is the recombining of some of the combustion products to produce large amounts of water vapor, which sucks a bunch of the combustion heat right back out of those flames, in a nasty Catch 22.

And so we come back to a fan-blown system's ability to burn a whole lot of fuel in a short amount of time; this is the real reason fan-blown burners are needed for natural gas. Why isn't this common knowledge? Because low pressure gas service keeps the overwhelming majority of forge and furnace builders from even trying to build a naturally aspirated NG burner, so they never find it out...fortunately.

Massive amounts of combustion produce massive amounts of hot exhaust gases. It's all very fine to set up a powered exhaust hood to keep the air in your shop breathable, but enough wasted heat is going to spill over into your shop to give the expression "dragon's breath" a whole new meaning. Am I knocking fan-blown burner systems? No; I'm saying "make your equipment building decisions in line with fact; not fiction." If you live someplace very cold through most of the year, heating the shop up is a good thing. If you live someplace that gets hot for most of the year, not so good.