IFB and castable base for ribbon burner forge

[rls1160]

Good morning all,

 

I àm a new poster and long time reader of the forum. I live in Cedarburg, WI which is about 30 minutes North of Milwaukee.  I have read most of the content in Forges 101 as well as the burner and ribbon burner sections.

I am converting from a coal forge to a propane blown ribbon burner set into floor of an insulated fire brick and castable refractory base.

I have included pictures of the forge stand and base form with IFB brick inlay and box out for burner placement.

I have also included pics of the Forge casting form and 4-1/4" X 6-1/4" ribbon burner based off the Pine Ridge burner.

The plan is to pour a 1" castable refractory layer on top of the 2300 degree IFB brick base.  i need to know if tye IFB bricks need to be mortared or set into refractory mortar prior to pouring refractory layer.

Second question is wether in need to insert refractory hangers or any rebar wire for the 1" castble floor.

I am using versa flow 60 high alumina castable refractory and have 1" ceramic board as an secondary outer layer of insulation if needed.

The forge casted shell will be 2" thick, followed by a 1" layer of ceramic board with a 16ga steel outer shell.  The interior hot faces will be coated with Plistix.

The door openings of the forge will be offset to right side allowing the burner placement to be far left hoping to create a nice flame circulation, retention of flame heat, and minimize flame impingement to the forge as well as the work pieces.

Thank you for your consideration and and thank you to everyone who has taken the time to post all your insight and knowledge on the forum.

Rick

[Latticino]

I am not familiar with that particular castable refractory mixture (hopefully it is a castable insulating refractory like Kastolite 30, not just a castable refractory like Mizzou), but it shouldn't be necessary to mortar the bricks together before casting.  You may want to include a sacrificial layer of wax paper on top of the bricks to keep the castable drying evenly, if you are planning on casting the crown in place.  Most castables like to be kept fairly moist while they are setting.

Rebar hangers or wire shouldn't be required in the castable floor either.  The arched crown may benefit from some form of reinforcement, though any part of it that gets exposed to the forge atmosphere will scale away pretty quickly.  I have used stainless needles available from refractory suppliers for this purpose in the past, which can certainly help with the fairly common cracking that you can experience as the forge goes through repeated thermal cycling.  They are absolutely NO fun whatsoever to mix into the dry material.  

The other recommendation I have for you is to modify your frame so you have some kind of compression member holding the bricks in place.  Angle with threaded rod is popular.  The lightweight bricks are pretty friable and become more brittle over time.  As I understand it, with your current design you don't have to worry much about the brick cracking, but you certainly don't want pieces falling off the perimeter.

As I've stated in the past, I have a theory that a burner block with long refractory outlets is more likely to suffer from preignition than one with shorter tubes, but I haven't had a chance to really study it.

[Buzzkill]

Unless you're planning on having more than one shell you can use for your forge you may want to rethink the floor mounted ribbon burner.  I ran a naturally aspirated floor mounted ribbon burner for a couple years.  There are some pros and cons to it.  It automatically gives you good swirl with a D shape overhead.  It is simpler to create/fabricate the shell.  However, as you can see from your picture, you lose about a third of your floor space with that arrangement.  You may also find that scale and/or small pieces of refractory that break loose from the shell end up on your burner head and possibly in the plenum of the burner.

If your burner were to be installed in the angled section on one side and pointed at the angled section opposite that should give you good swirl and maximize your floor space.

If you don't mind losing the floor spaces and the occasional cleanup of the burner you'll probably really like that setup though.  On my most recent build I went back to a side mounted ribbon burner and overall I like it a bit better. Your mileage may vary.