Case Study · Iron & Steel
Radiant Tube High Emissivity Coating: Exit-Gas Temperature Down 70°C at Oxelösund
| Industry | Iron & Steel |
|---|---|
| Asset | Radiant tube (Kanthal chrome-nickel) |
| Customer or location | Oxelösund, Sweden |
| Products used | Emisshield metal coating, sintered at 815°C |
| Headline metric | Exit gas 500 to 430°C |
| Secondary metric | Life projected 3 to 5× |
| Also measured | Natural gas |
A radiant tube at an integrated Swedish steel mill showed 500°C exit-gas temperatures, hot spots, and premature oxidation. The tube was grit-blasted, coated externally with Emisshield, and sintered before installation. Exit-gas temperature dropped to 430°C, indicating more heat transferred to the steel, hot spots and oxidation diminished, and tube life is projected three to five times longer.
01
What was the challenge?
Improve heat transfer to the steel, reduce tube temperature, and extend service life.
02
What was applied?
External coating of the chrome-nickel tube, sintered at 815°C, then returned to natural-gas service for evaluation.
03
What were the results?
| Metric | Uncoated | Coated |
|---|---|---|
| Exit-gas temperature | 500°C | 430°C (−70°C) |
| Heat flux to steel | Baseline | Improved |
| Hot spots and oxidation | Present | Reduced |
| Projected tube life | Baseline | 3 to 5× |
Operators noted the coated tube outperformed more exotic and expensive alternatives, improving energy efficiency and reducing replacement downtime.
04
Why did it work?
A high emissivity tube surface radiates more of the combustion energy to the load, so less leaves as hot exit gas, and uniform surface temperature slows oxidation. See Energy Savings.
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