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Hello!
I read something like this "......unsuccessful in steam-air decoking of Visbreaker furnace. An iron-oxide layer had formed on top of coke and shielded it. Reduction step with hydrogen is now often used prior to final steam air decoking".
Can anyone explain
1. How iron oxide forms over the coke?
2. How can we ascertain iron oxide layer formation?

Thanks
Lakshmi