Don't understand using venturi burners

[Frosty]

I wouldn't solder outlet tubes to the plate.  I don't know the correct term but I don't THINK baffle is what it is. It isn't baffling anything and I looked at the Pine Ridge burners. FINALLY I found the name of the component as applies to boilers! I've been looking online for a couple hours and spent time talking to HVAC repair guys and they couldn't help me. In a boiler the analogous part is called a "tube plate." Talk about getting lost in finicky details, how's THAT Mike?

Anyway, I'd use SS brakeline, it's a thin very flexible alloy and would yield to the hard refractory's different COE. You can buy swages and flare tools designed to work with it.

So, I'd simply drill the "tube plate" a couple thousandths undersize, swage the tubing to pass and flare the other side till it seats on the swaged shoulder. 

COE differences between the hard refractory block and the tube plate is the reason there is a gap to allow movement. The gap would also serve as a heat break, the incoming fuel air flow acting on the tube plate will serve to keep it cool enough to prevent back burning. Were it in direct contact with the block conduction would eventually heat the system to the burn back or flash over point. Not to mention the different COEs shearing tubes from the tube plate.

This space would be a natural place to install ceramic blanket if further insulation were deemed beneficial.

Another benefit of a tube plate construction is reduced friction to the fuel air flow further reducing the static pressure necessary to operate efficiently and equalizing the pressure through out the plenum for more even flame length across all outlets. 

I can think of a couple few construction issues to winkle out but it's getting more intriguing all the time. 

Frosty The Lucky.

[Mikey98118]

I think the the incoming mixture tends to keep the tube from expanding to much against the ceramic block. Making the hole in the block a few thousandths oversize is added insurance and makes assembly easier. The genius of this method is there is no possibility for a gas leak when the burner is running, because the flame will induce the mixture toward the hole openings, instead of allowing it to leak backward away from the flame.

[Frosty]

Causing COE problems with the tubes in the block is why I was thinking SS brake line would be a good candidate, it's flexible enough a little crushing pressure would only cause it to flex. I don't know how well making the holes a couple thou. oversize would work, it's an added construction hassle and I'm too lazy to deal with more than I need to. I think I'd mess with finding tubes that do the yielding without deforming and just cast them into the block.

Naw, as long as the ends of the plenum and intake fitting don't leak I don't think leaks are a factor. The plenum is under pressure so any leak is going to be pushed out into the furnace. If the leak has no outlet then the mix psi will just equalize behind the leak and bleed off when the burner is shut down. Again no consequences, ignore it as a non-problem.

Hand making a multiple outlet, naturally aspirated burner with metal outlet tubes and a tube plate would be a heck of a lot of work. Just developing a workable method of making the things is a serious job of work. 

It'd be a LOT easier to dig the trench, wire the shop, move the lathe, turn split tooling, make the scissor tools. adapt the tool rest and start spinning jet ejector burners with full length tapered tubes and proper venturi intake ports. Once set up, spinning the intake, tube and outlet nozzle for easy connection is just production work I grew up doing. LInear, ejector, same same. 

Frosty The Lucky.

[customcutter]

On 5/19/2017 at 2:41 PM, Mikey98118 said:

David,

So, anyway there are two good answers to your question:

(1) I have seen many people in love with their gas forges, and just as many who hate theirs. Neither group necessarily knows beans about either their forges or its burners. The deciding question never ends up being what kind of forge or burner someone has, but how well it was built. A properly constructed naturally aspirated burner will out perform a poorly built fan-blown burner, and visa versa. Ribbon burners--even homemade ones--have great heating potential from less fuel, because many small flames can slow down much faster than a single large flame. Even multiple miniature  naturally aspirated burners can't do as good a job of slowing super-heated gas down from a fast flame; this is obvious on the face of it. On the other hand, the law of diminishing returns will even out the difference equally fast! They ain't no such animal as a perfect burner; ditto for perfect forges.

(2) Jewelry stores show hundreds of pieces for sale, rather than just two or free "perfect" items, because people want CHOICES. So one mans 'perfect' burner is another man's junk. Junk isn't necessarily something bad. But, like weeds, may simply be unwanted. So, if I was making a miniature forge in a helium cylinder the smallest ribbon burner anyone can make would be monstrously oversize in return for very minor fuel efficiency. At this point I could ask why would anyone want a clunky ribbon burner, when their are hot little NA burners in the world...and be just as wrong as I could be, in your view  

Dang. but this has proved to be a good thread!

I was doing research trying to find information on which is more efficient a NA burner, or a forced air burner.   Because I had seen a forced air burner running at 2 PSI, I was thinking it had to be more efficient.  Then I found the answer, well it was 2 PSI but at a much larger orifice.  Now Mikey has dropped the gem, saying that ribbon burners are the most efficient.  So I'll read Frosty's thread on NA ribbon burners for the 3rd time.  I really would like to get started building my forge some time in the next week, just trying to decide on the burner and forge as a whole.

thanks,  Ken

[Frosty]

Ken: Efficiency is purely a matter of how much fuel air mix you can burn in the forge in a given amount of time. The psi on the propane tank doesn't mean anything regarding efficiency. All the gauge allows the operator to do is repeat fuel outputs without having to tuning a NA burner that is. A gun burner (blown) requires you to adjust both fuel and air when you want to change the temperature.

A NA burner relies on a hi velocity jet of gas to induce combustion air this requires a smaller jet diameter delivering at a higher pressure.

A gun burner only needs the correct amount of propane so it doesn't matter what diameter the jet is. The larger the hole the less pressure required to deliver the SAME volume of propane.

A properly tuned burner, NA or Gun, will deliver the exact same BTUs for a given volume of fuel air mix.

One of our club members has a really nice little factory made gun burner with an outlet diameter maybe 1/2" dia. I just eyeballed it, when I asked the owner he just shrugged and said it's metric and he doesn't care. Anyway, it brings his fairly large forge to welding heat easily but the downside is how fast the flame is moving. The forge has a major case of dragon's breath, you can watch significant fuel being wasted as it burns a couple feet outside the forge. 

It isn't a forge burner though, it'd intended for a fairly large bronze melter, upwards of 30-40lb melts. 

There are up and down sides to either basic burner type though. Guns are easy to build and require minimal shop skills. Down side is they're tied to electricity and you have to tune them every time you change the output. NA burners require some shop skills a few more tools and can be finicky getting tunes correctly. On the up side, once tuned the induction curve is darned flat so all you need do is change the fuel to change output it's self metering.

Frosty The Lucky.

[David Kailey]

On 5/12/2017 at 9:25 PM, Buzzkill said:

 

I use a 3/16 nozzle

My blower uses less then $1 a day in electricity...... so says my electrician 

[ThomasPowers]

My forge blower uses US$0 in electricity; of course that may change if I ever get electricity within 25' of the shop!  Or on campouts, or demos at historical sites, or...

[Buzzkill]

I think the point he was making is that the cost of the electricity is essentially a non-issue when comparing the cost of running a blown ribbon burner to a naturally aspirated single port burner.  I agree, but now I'm working with a naturally aspirated ribbon burner and feel like I'm getting the best of both worlds to a large extent.

[Mikey98118]

I'm a fan of ribbon burners, BUT, how well they work depends on the builder, just the same as gun burners, and naturally aspirated single flame burners.

[WayneCoeArtistBlacksmith]

Mikey, if anyone follows the plans written by John Emmerling at the Ribbon Burner Forge attachment at the Forge Supplies page on my web-site they should get a good , efficient build.

Let me know if I can help you.  My contact info is on my Profiles page.  I prefer e-mail.

Wayne

[Mikey98118]

I would agree with you about Emmerling's directions, Wayne. But there is a whole lot of innovation going on with these burners; I'm a fan of that too. But innovation leads lots of room for mistakes. Such is life.