Forge modification question need advise

[Sean Blum 13]

So this is my current forge that I built last year.

 

The chamber size is roughly 7" diameter and 16" long so about 615 cu in. The burner is a 12"x3" ribbon burner made with my brain with a flu approximation of the Wayne Coe method. The problem I am having with it is that if it is used for too long it will overheat the manifold and start backburning. I believe the cause to be that the burner is too large for the volume of the forge chamber so I am planning to replace the burner with a smaller one unless I get some new ideas as to the cause. It is still operational as I tried increasing air to oxidizing atmo but it will only delay it and turning the needle valve to 3/8 of a turn will get it to just under high carbon welding heat and a 1/2 turn will weld mild steel. If I try using more gas to increase the airflow to help cool it it just makes it hotter or to hot for the material. My current work around is if Im using it for a while I periodically open the front door to cool off the forge.

 

My current plan is to remove the old burner hopefully without severely damaging the lining and replace it with a 6" burner unless anyone thinks I should go with a different size than that.

 

The part I have a question on and need some advise other than the two I pointed to earlier is how I should go about filling the two 3" voids on either side of the burner. My plan was to just fill the open space with castable but if that is a bad idea I would like to know before I try it. I figured they were small enough not to need wool as they wont be the worst heatsinks and I am unsure if I should just leave them as casting to the air or weld cover sheet over them.

 

Any input would be greatly appreciated.

[Charles dP 493]

Bearing in mind that I don’t have a ribbon burner or any experience with one; wouldn’t it be easier just to block up some of the holes in the ribbon burner to get less flame?

[Geoff Keyes 525]

I'm with Charles, find some SS bolts that will screw into the holes and block 25% and see what you get.

 

Geoff

[Sean Blum 13]

It sounds like it would work but I would worry about thermal expansion of the SS. If it expands more than the refractory does wouldn't it just tear it apart? Or if the castable expands more than the SS it just gets forced out by pressure or falls out?

Edited February 8 by Sean Blum

[Alan Longmire 2,821]

Maybe stuff some castable in the holes?  Harder to remove if it doesn't work, but no issues with expansion differentials...

[Sean Blum 13]

Yeah I thought of that right after I posted my response so I'll probably give it a try. I'll leave the question open though in case it doesn't work so if I need to do the original plan I wont need to repost.