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Natural Gas Ribbon Burner


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First post here, folks. Name is Jason. I'm actually a metal caster and found my way to you guys via some searching. While i fire a metal casting furnace on used motor oil, I was looking for a quicker way to fire a forge I was building. I'm from west texas and coal isn't something we have here. Lots of oil and natural gas, but no coal. To make things worse, propane is dumb money in my neck of the woods so I set out on firing a forge with natural gas. This thread is my adventure into what took me way too much time to solve. Hopefully this will help someone looking to do the same thing.

 

The Problem: As you propane burning people know, you guys can get regulators to blast out at 30psi and even 60psi and that's why you can get away with a normally aspirated propane burner or "supercharge" it with a hair dryer or compressed air line. Household natural gas pressure is only delivered at about 1psi. VERY LOW, slow and LAZY. There is no way to boost this PSI without expensive engineering. There are companies that sell natural gas forges and these can be expensive and are usually very large.

 

The Solution: Must create a large enough mixing chamber and an effective way to safely and smoothly deliver the collected low psi natural gas and get it to burn INSIDE an enclosed space.

 

Nothing I did here is new and I cannot take credit for this. The real brain child behind this is John Emmerling, His simple instructions can be found here. http://www.waynecoeartistblacksmith.com/uploads/Ribbon_Forge_Burner.pdf Thanks Wayne for posting this on your website.

 

On to the build and all my trials and tribulations.

 

This is how i WAS heating metal. Some might call it a vertical forge, but I call it a furnace. FIred with used motor oil, it has a hinging lid to allow the crucible to be lifted in and out of the heat. Used oil has the BTU's to easily reach cast iron temps and is essentially FREE to operate for long periods of time.

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Here is some work on the tank itself. I thought having one end hinge would be a good idea for larger work. This haunts me later as you'll see.

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Stand

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2" x 2" x 6" 1/8" wall box section. Note diffuser plate with holes welded 5/8" from 2" opening on the inlet side.
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Ends closed, That 1/2" lip is what secures the refractory to the body of burner housing.

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Crayons mounted on plywood for burner hole pattern

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Large 2" hole for inlet

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Wood former

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Completed form

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Setting depth for casting

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Refractory filled form and metal box

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Removing the forms

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Mounted in top of furnace

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View inside the furnace. No METAL of burner body can protrude inside furnace!

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Here is where and HOW the magic happens. The natural gas must be introduced to burner (in distance) per this

>>>> Diameter of pipe (2") X 9 = MINIMUM entrance in inches. My case 18" from burner. Reason for this is to allow

the natural gas and blown air to mix. If feeding this thing with propane, You can put it closer to the burner and shorten up the pipe.

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Test firing burner outside the forge

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test fire outside furnace. Shoots a nice 4ft flame

 

Firing inside the tank

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Another view inside from the hinged side.

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Full steam ahead right? Well, here is where I get a little sideways with this project. Looks like it burns great right up to the point where I close the hinged door. With the door closed, it flamed out. It became very hard to light, unstable, and just about downright scary. Lots of poofs and woofs.. I started to reconsider this hinging door and really the need for it. My openings are 4"x4" on the back and close to 6"x6" on the front. I decided to weld the back end of the tank on it. Further test firings still showed I had SOMETHING going on with this. I tried running it lean, I tried rich. I tried every blower I could find from hair dryers to large squirrel cage fans, shop vacs and paddle style fans. It is important to remember a fan is not necessarily a fan. Squirrel cage fans do not handle back pressure well. When back pressure happens to a squirrel fan, the motor slows down and stability can become an issue. Better option would be a paddle blade setup. Well, last night it finally occurred to me, what I was doing was introducing this forced air/gas mixture into a tank without a clear path to it's exit. This created a turbulent environment and made the flame highly unstable. I still hadn't added the Kaowool or Mizzou refractory cement to this as I didn't know if the burner was here to stay or would I end up on a normally aspirated propane burner. I decided last night to mock it up stuffed with 2inches of Kaowool and light it again.

 

As they say, the proof is in the pudding. The flame lights with ease. Turn on the air, slowly introduce the natural gas and it lets out a gentle poof and it's off to the races. It's VERY stable, and dare I say it now, REALLY HOT! I still have more work to do, adding the usual assortment of air flow valves, fine adjustment for gas control and other crap I can screw to this thing. At the moment, my fan is a whimpy microwave oven blower and the gas line is 1/2" feeding the burner. My fan is running full tilt and natural gas valve is hardly even cracked open. This is exactly what I want. Plenty of headroom to increase the heat by adding a larger fan and increasing gas flow.

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And here's a small video of it running.

Stuffing this thing with the Kaowool allowed for smooth exit of airflow. PROBLEM SOLVED!

~side note~ Kaowool should be covered with Mizzou, ITC, Kast-o-lite, keeping silica out of your lungs is important.

 

Hopefully this might help some of you that are considering dumping your expensive propane and trying natural gas. I can already see many applications for this. It burns clean, CHEAP, lights easy, stable, could be extremely safe with the addition of flame sensors and solenoids to cut fuel in the event of a loss of the blower or even power. Compressed air could also be another option easily rigged in place of an electric motor so close to a pipe full of gas. Many question why the flame doesn't travel back up the pipe to the source. Well, the pipe remains under pressure and the pipe is a fixed size, therefore the theory is the flame has no where else to go but forward. In addition, multiple ribbon burners could be stacked, or a 3foot burner could be made just the same. Today, with the net, we stand on the shoulders of giants and each time, we get to see a little further than the last guy. So grab your man card and let's see where this takes us.

 

Thanks!

 

Jason

 

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Yup, household gas pressure. I'd be surprised If I have 11". I measured it once with a home made manometer and it was around 7". Not sure if this helps, but the house is plumbed with 1" pipe, and I reduced it down to 1/2" about 50feet prior to dumping it into the forge. This is a photo of my regulator.

 

Anyone know what this means?

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Not completely sure, but theorize that it is a residential rated pressure regulator with a 3/16 orifice between the supply side and the outlet. Probably has a fixed spring on the diaphragm to set the outlet pressure within a certain range of operation. Not recommended, but it might be capable of some adjustment by either changing the spring itself or the spring setting, if adjustable.

 

I am currently tuning up a relatively similar natural gas/forced air forge with a ribbon style burner. Am not happy with the stability of the flame currently (the gas/air mixture velocity is too high when set at a reasonable heating rate and the flame pulls away from the front of the burner tip), so will have to adjust same. I also have low pressure residential natural gas, but am using a commercial mixer and regulator to address modulation. I believe that my solution will be to increase the size of the ports for the ribbon burner outlet. You may have to do something similar.

 

Good luck.

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I suggest a gate valve on the air intake and a 1/4" needle valve for the gas. Then you can adjust air and gas just like an oxy/fuel torch.

If you have problems finding 1/4" needle valves with NPT you can contact me.

Let me know if I can help you.

 

Wayne

Edited by Wayne Coe
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Thanks Wayne, but I'm running 1/2" across the board. Oil burner, Kero burner and NG. If it wasn't for the gas lanterns hanging on my house, I'd have 1" feeding the show. :-)

 

I'd like to find this blower used on this page by Eric... http://www.bladeforums.com/forums/showthread.php/934512-Table-Forge-with-Ribbon-Burner

Anyone recognize it?

Edited by JAndrews
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That's the one I'm using on mine. It isn't ideal (still a squirrel cage), but is built fairly robustly and seem to give plenty of air for a standard forge size. Setup properly it should do the trick.

 

The best choice for an air valve is a butterfly valve (though they are hard to source). A gate valve is a good second choice, and certainly better than using a ball, globe, or plug valve. For those who are unfamiliar with these butterfly valves they look like this:

 

butterfly-valve.jpg

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Your right Dan. It's still a squirrel cage motor. :-/ Ya really would think they would know better than to produce that thing for a forge. I'll dig through my HVAC crap for now. I'm sure I've got something just as good at a free price.

 

Correct me if I'm wrong, but isn't a centrifugal setup with a paddle blade the best for pressure? Blower design seems to be a black art to me and I can never keep them straight. lol

 

Just found this... Looks very helpful. http://www.saylor.org/site/wp-content/uploads/2011/09/Chapter-3.5-Fans-Blowers.pdf

Edited by JAndrews
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A gate valve is more infinitely and precisely adjustable than a butterfly or a shutter. I tried it with the shutter that came with my blower and found that it was difficult to get the setting I wanted and worse to try to duplicate the adjustment.

Edited by Wayne Coe
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A gate valve is more infinitely and precisely adjustable than a butterfly or a shutter.

 

Gate valve will afford you more precision, but it is not necessary clear that precision in valve setting is required. In my experience speed of modulation is more critical, and a butterfly works better for that. You get the precision from having a pressure gauge or manometer hooked up to your air piping. Probably the best type of air valve is an iris valve (think old school camera lens iris). I've never seen one in the small size we use for burner systems, but I expect they exist.

 

 

Correct me if I'm wrong, but isn't a centrifugal setup with a paddle blade the best for pressure?

Yes a paddle blade fan (as in your link) will give you good high pressure/low flow conditions. A lot depends on the burner and air piping design for your system. If it is very straight and short with minimal choke points and smooth sides the friction looses are minimal and you can get by with a standard FC Centrifugal fan. If you have anything complicated in the mixing chamber, long air lines, a significant rapid expansion, many short radius bends or a "break the back" elbow just after the exit for your blower, you may need a fan with more pressure. I used to use a larger radial fan to run several Natural Gas burners simultaneously. Now I'm trying the one you have for a dedicated forge with a ribbon burner. It currently runs, but needs some modification. Once I know for sure it will work I'll try to post details. I am using industrial components though, so my system won't perform identically to yours. It did work well enough when I used it with a standard 1 1/2" flame retention tip, so I expect it will work with the ribbon burner once I get the ports dialed in.

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Got my Nat Gas/forced air ribbon burner forge fired up last night for a first real trial. As theorized the port size for the multi-port ribbon burner were too small. Drilled them out and was able to get stable operation at full fire finally. Forged a quick wall hook out of mild and was quite satisfied with the heat level inside the forge. Checked it with a pyrometer and got a reading of 2400 deg. F. Expect when I finalize the installation I will get more heat as there were still some small openings around the burner block port and the door system is not optimal by any means. Was using that blacksmith depot blower, so expect it will work for a conventional size gas forge (mine is around 230 cu inches, half circle crossection with flat bottom down).

 

As an aside, I piped the burner connection tube with a threaded union so I can easily swap out this smaller forge for my larger cylindrical forge (unfortunately they have different burner ports so I currently can't use the ribbon burner on the cylindrical forge. Still a good idea for a small shop where you don't want to pipe up multiple burner assemblies. Will post photos to separate post after I get things finalized if anyone is interested.

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2400 F is 600 to 800 degrees too hot for most forging operations. You'd like to be able to run at a stable 1400-1500 F for a lot of HT operations. 2400 F is sort of middle range for welding operations. This is the problem for most of us, we think we want HOT, when what we need is much less than that. For melting and casting, that is outside my experience, you'll have to tell us.

 

Geoff

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Nice work Dan. 2400degrees is impressive on NG. I do metal casting and melting with diesel and used motor oil. I might look later at rebuilding my furnace with a pair of large ribbon burners. No question, this sucker is here to stay in my workshop. My forge is slowly curing it's mizzou now, I'll put the flames to it soon.

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2400 F is 600 to 800 degrees too hot for most forging operations. You'd like to be able to run at a stable 1400-1500 F for a lot of HT operations. 2400 F is sort of middle range for welding operations. This is the problem for most of us, we think we want HOT, when what we need is much less than that. For melting and casting, that is outside my experience, you'll have to tell us.

 

Geoff

Geoff,

 

You may have me confused with the OP. I am not contemplating doing any melting or casting at this point (though who knows, I could take a class and look into bronze I guess. Have plenty of graphite to machine crucibles out of). As long as my tools are under around 16" in length I have a dedicated electrical Heat treat oven I built with a programmable PID controller that can easily run up to 1550 deg. F. If I ever need a longer one I have coils and mercury contactors enough to make one. Or I will make a simple sword heat treating tank from a 55 gal drum and some frax using the Don Fog design. I've seen those work extremely well.

 

I do want my gas forge to get up to reliable welding temperatures, ideally wrought iron working and welding temperatures. I can certainly work wrought at 2400, but I still have my doubts about welding it. I've been more successful with my forge welds to date using a coal forge (other than welding up all high carbon steel like cable for instance). Need to do some tests to see how it will work once I get the installation completed. I am happy with my test of concept that brought me up to 2400 though.

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When I do fluxless welds in my Ribbon Burner forge I watch the pyrometer for 2315 degrees and hold it there for a good soak. I also make sure that I have a reducing atmosphere..

Thanks Wayne. That sounds promising as I can easily vary my forge atmosphere with the piping setup I have.

 

Are you using a type K thermocouple, or have you gone with Type R or S?

Edited by Dan Hertzson
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Nice work Dan. 2400degrees is impressive on NG. I do metal casting and melting with diesel and used motor oil. I might look later at rebuilding my furnace with a pair of large ribbon burners. No question, this sucker is here to stay in my workshop. My forge is slowly curing it's mizzou now, I'll put the flames to it soon.

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Intriguing setup. I'd love to watch it firing at some point. You are braver than me with the casting. Potential for safety issues scares me a bit for that. Have to find a class somewhere.

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This is how ya do it. Don't ask where the gear came from. Cost me a lot of beer and some deer meat. That's all I'm gonna say about that one. ;-)

 

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I started to firing it slowly tonight to cure the mizzou. First run was only to a couple hundred degrees, slow cool down, then back up higher to around 700degrees.

Just finished up and it reached 1850degrees. How might you ask?? Here is the worlds cheapest pyrometer. I use it for dipping into crucibles of molten metal. If anyone wants a build thread on it, just say the word. It's a WINNER and less than 40bucks! I do believe with a bigger blower, I should get her another 500degrees out of it. (I hope) I'm not planning on doing any forge welding in this thing. But getting metal back up to temp in a hurry is always the goal. I was getting low on mizzou, so I ran 3layers of 1inch Kaowool and one inch of mizzou.

 

Only about 500degrees here.

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Cheapo Pyrometer made with a 1/2" gouging rod.

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