In this year turn around, we will replace castable of top-part (almost half) of secondary reformer. Which one is better for drying out : by process gas (initialized by nitrogen circulation) or by portable burner located inside the reactor. We had experienced once when using process gas (for upper part of reactor), the death zone of transfer line outlet secondary was hot spot, due to the damage of castable on there (one of the reason was introducing water from the top reactor while drying out was progressing). Thank you.