Forge plan, ribbon burner question

[Bob Ouellette]

I'm planning on building a forge that will have an adjustable chamber size. I'm planning on having 2 ribbon burners. The first will always run when using the forge and the second will be turned on whenever the chamber is opened up for larger projects. A hard fire brick will be used to adjust the size of the chamber.

 

My questions are, first, what is the best way to infect the fuel? Second, what size openings should I cast into the burner? I'm going to use a blower mounted under the forge table to force air into the burners. The burners will be about 3" wide and maybe 7" or 8" long.

 

Here's a side view drawing of the forge. I plan on having a valve where the vertical line is between the two burners.

 

[Alan Longmire]

The ones I've seen and used were made by using ordinary crayons for molding the holes.  I think Wayne Coe has plans on his page.  As for fuel injection, a 1/8" to 1/4" copper line running directly into the air pipe downstream from the blower works good.  A needle valve on the copper line is good.  

[Bob Ouellette]

Thanks Alan. I plan on having individually adjustable burner valves, so I'll put the inlet in after the pipe turns down towards the burner.

[Chris Christenberry]

I used 129 1/8" cocktail straws and get a mighty nice flame..............or, actually, no flame at all, but a white hot interior if I need it.

 

https://chris623.zenfolio.com/img/s/v-11/o1066304653/c1/p3866474508-200.mp4

 

This was my first firing and I didn't take it up as high a heat as it would go.

 

 

Edited January 3, 2021 by Chris Christenberry

[Sean Blum]

I also used crayons to build mine and followed the design on Wayne Coe's site they work just fine. Just remember you want to roughly match the area of the intake portion of the manifold to the total area of the number and size of the holes in the burner block. This means you can go smaller to a point you just need more though I would avoid much larger as you tend to lose that even heat distribution with less holes.

 

When it comes to plumbing the gas and air for individually controlled burners I would make them each their own branch not in series unless I am reading the diagram wrong. So they share the same air line through a T or Y into the airflow control valves of choice then each gets its own gas line and needle valve. If you want to run it in series then you have less independent control over the burners as a unit but its more straight forward and less parts.

[billyO]

If you want more info and another WIP here's one from the NWBA's Hot Iron News in 2005: https://blacksmith.org/2005-1-hot-iron-news/ pages 11-14

 

Never mind, I just checked out Wayne's site and it looks like he's using the same source.  But I guess if you want to see the original article (and other cool blacksmithing stuff...)

 

Edited January 4, 2021 by billyO

[Jaro Petrina]

I think you will have to have valve on that second burner to avoid the flame going back, when its not in operation. (Alongside the needle valve for the burner).  Probably could be good to have it on both channels.

[timgunn]

11 hours ago, Bob Ouellette said:

Thanks Alan. I plan on having individually adjustable burner valves, so I'll put the inlet in after the pipe turns down towards the burner.

 

I wouldn't.

 

I'd put the fuel inlet out to the right of your picture and I'd definitely only have the one.

 

Having a gas inlet per burner means you are going to have to adjust both to the same mixture to get the same air:fuel ratio and flame temperature from each burner. That simply ain't gonna happen, at least not regularly. If you inject the fuel and mix thoroughly before the burner feeds separate, both burners will always get the same mixture without any faffing about on your part. 

 

I might also look at redesigning the manifold. I think the left-hand burner will tend to have a bigger flame than the right-hand one simply because flow is past the right-hand burner, which I think would tend to reduce the static pressure to that burner, and hits the end of the line at the elbow into the left-hand burner, which I think will tend to increase the static pressure. This may suit your application, but in general, I'd aim for symmetry in the system.

 

Most folk seem to have success with a relatively large "gas jet" on blown burners, using a needle valve to control gas flow: effectively a fixed-pressure, variable-area adjustment mechanism. The "gas jet" can be as simple an open-ended tube. It is also possible (and equally effective) to use a gas jet which provides some restriction and gives a fixed-area, variable-pressure adjustment system.