Hydrofining reactor shutdown
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The hydrogenation refining reactor has been shut down; is dehydrogenation required?
Of course it is necessary. The so-called dehydrogenation process involves slowing down the cooling rate to prevent hydrogen molecules that enter the reactor from not having enough time to escape, which could otherwise cause cracks in the reactor
Dehydrogenation is necessary; during normal production, hydrogen molecules penetrate into the material. If dehydrogenation is not carried out during shutdown, it can cause cracks and bulging in the hydrogen-related systems!
This is primarily to prevent hydrogen embrittlement; when the device is shut down, the cooling rate should not be too fast. Moreover, during the shutdown process, there should be processes to help release as much of the hydrogen absorbed by the steel as possible (through staged isothermal dehydrogenation, with the dehydrogenation temperature generally ranging from 260 to 427°C), in order to reduce the residual hydrogen content in the vessel walls. Additionally, it is also very important to avoid unplanned emergency shutdowns (emergency venting) as much as possible. Because the residual hydrogen concentration in the wall under these conditions is very high.
Dehydrogenation must be carried out; the pressure should be reduced first followed by a decrease in temperature. It is essential to strictly control the rates of temperature and pressure reduction in order to allow the stored hydrogen to be fully released.
It mainly depends on the material of the equipment; for stainless steel, I don’t think it’s necessary to schedule a dehydrogenation process – normal cooling and pressure reduction during shutdown are sufficient.
Of course it is needed; isn’t the nitrogen displacement and cooling during the shutdown process a form of dehydrogenation treatment?
We rarely talk about the dehydrogenation process. Here, the shutdown process involves a phase of hot hydrogen carrying oil, which lasts for a long time; the main task during this phase is to carry the oil. I’m not sure if this refers to the same thing as dehydration mentioned by the original poster.
Dehydrogenation is necessary; during the shutdown process, care must be taken to control the rate of temperature and pressure reduction, and the system should be purged with nitrogen to prevent damage to the equipment. One of the hydrogenation heat exchangers in our unit leaked within just a year of being installed; it is suspected that the dehydrogenation process was not properly controlled.