A Special Veneer Coating to Preserve Ladle Preheaters
If you’re in the steel industry, especially the melt shop, you know how difficult it can be to get several heats from your ladles, much less from your ladle pre-heat covers. What do you do when your ladle pre-heat cover develops hotspots, loses its efficiency and runs hotter than normal?
Instead of replacing the cover or the refractory lining, there’s a viable option that not many in the melt shop know about. It’s called a Foamfrax veneer coating, and it’s an easy way to extend the life and efficiency of your refractory at a low cost.
It’s unique. And it’s effective.
This case study outlines how we used a veneer coating in a recent project in the melt shop of one of our client’s facilities.
This facility has large ladles (approximately a 10 ft. diameter and 15 ft. tall) that hold molten steel. The ladles are lined with refractory. The mill preheats the refractory in the ladles to reduce thermal shock when the molten steel hits the refractory and to help maintain temperatures.
The preheating process involves having huge overhead cranes lift the ladles, tilt them to a horizontal position and then slowly move them toward a refractory-lined wall, which is about 12 ft. tall by 12 ft. wide. The lower portion of the wall is castable and the upper portion is ceramic fiber, at about 12 inches of thickness (some other preheater configurations may vary).
In the center of the wall is an opening with a burner. The cranes move the tilted ladle to the wall and the burner heats the ladle to heat the refractory.
Previously, replacing the refractory on the ladle preheater walls required the mill to tear out all of the ceramic fiber modules and replace them. This wasn’t an optimal solution because it’s time-consuming work that requires a lot of downtime.
Here’s a shot of the wall:
Instead of tearing out the walls and replacing them, we presented an alternative solution, based on our experience as a Unifrax distributor.
Foamfrax is a unique, proprietary form of ceramic fiber made by Unifrax. Foamfrax is sprayable, similar to gunite, and installation requires a special machine to pneumatically convey the material. F.S. Sperry is the #1 Unifrax distributor of their Foamfrax product, and we own machines as well.
Our solution was to spray the Foamfrax ceramic fiber to create a veneer coating, approximately 2’’ to 4’’ thick, across the entire wall to “thicken up” the ceramic fiber to its original thickness, just like a new wall.
We performed this work quickly, in a single day with minimal downtime for the mill. The mill asked that we add the veneer coating to only one of the preheater walls, so they could test to see how well it held up.
Twelve months later, the veneer coating was still holding up well. Our client has now asked us to add the veneer coating to the other ladle preheater walls.
Once people see the results, it’s really a “no-brainer” decision because it:
- Is easy and quick to install
- Requires little to no downtime
- Is effective
- Extends the life of ceramic fiber
- Is less expensive than a complete rebuild
Veneer Coating Applications
Most plant engineers and maintenance personnel are familiar with ceramic fiber. But many are just learning about how adding a veneer coating with our sprayable Unifrax Foamfrax ceramic fiber can extend the life of their existing ceramic fiber lining.
We have several different grades we can use in different applications, and are only limited by our (or your) creativity! For example, if your furnace is running hot, and your refractory has deteriorated you don’t necessarily need to replace it.
We’ve extended the life of old furnaces by up to four years, saving customers substantial amounts of capital via reduced energy costs, less downtime and delayed equipment replacement costs.
We can apply these veneer coatings to
- Ladle lids
- Consumable ladle lids
- Ladle preheater walls
- Tunnel furnaces (on the vertical upper side walls)
- Roller openings
- Lower castable lining in the lower section of the tunnel furnace (below the rollers)
- Castable end panels and doors (if ceramic fiber)
These coatings are quick – we erect some scaffolding or use a manlift, and then we can cover a lot very quickly. The time savings is huge. There’s very little downtime. The coatings are very cost effective.
Contact us to schedule a visit to see if a veneer coating is right for your facility. Once people learn about it, it’s a no brainer! You can also access application videos and more case studies about our Foamfrax veneer coating for ceramic fiber here.