During shutdown, should the Claus catalyst be subjected to thermal soaking first, or should sulfur be purged directly?
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I would appreciate it if the seniors could explain in detail how to handle different situations under normal shutdowns and emergency shutdowns!
Since heat soaking requires burning H2S as a fuel gas for sulfur blowing, heat soaking is first carried out using hydrogen sulfide; however, it is necessary to maintain the temperature of the converter to prevent excessive temperature rises. After that, the fuel gas is used for sulfur blowing. This is my personal understanding, for reference only
In a normal shutdown, hot soaking is definitely carried out first; the purpose of this is to remove sulfur adhering to the catalyst bed. Our current procedure involves hot soaking, followed by stopping the flow of acidic gas and using hot nitrogen to drive out sulfur, then catalyst passivation, and finally cooling down the system. In an emergency shutdown, there’s no time for all that – acidic gas flow is simply stopped immediately
Heat immersion is used for sulfur immersion; after that, the bed temperature is raised by about 50°C, with a ratio of 4 maintained to facilitate the removal of sulfates. Only after that is the sulfur removal process carried out, at which point part of the exhaust gas needs to be removed
Hot blowing with sulfur has certain advantages; direct hot nitrogen blowing is also an option.