“\"Flying temperature\" and \"ignition\"”

Good question, I’m puzzled by this too. It seems that the fire starts first, and then the temperature rises. The reason is that sulfur (or iron sulfide) in the reactor caught fire due to excess oxygen.

Both bed temperature surge and bed ignition refer to an excessive rate of temperature increase, but they are not the same concept. What we commonly refer to as a bed fire is caused by an excessive oxygen level, which leads to combustion inside the reactor. Things such as the spontaneous combustion of ferrous sulfide or the combustion of sulfur can occur. Once such a fire breaks out, it inevitably results in a sharp rise in the temperature of the bed, which is what is meant by \"bed temperature spiking.\" This phenomenon is quite dangerous; if not controlled in time, it can cause the catalyst to be damaged due to the high temperature ； A sudden rise in bed temperature does not necessarily mean a fire has occurred; it simply means that the temperature rises quite rapidly. For example, when we increase the temperature of the bed layer, if the rate of increase is fast, this can also be considered a sudden temperature rise. It doesn’t necessarily mean a fire has started. However, in most cases we encounter, the likelihood of a fire being present is higher, and that’s why it’s referred to as a bed layer fire. This post was last edited by adsl121 on 2009-3-26 15:01]

I believe that bed temperature rise is an inevitable consequence of bed ignition. Because people cannot see whether the bed is on fire; they can only judge by the phenomenon of a sudden rise in temperature in the bed. Under normal conditions, the reactor bed will only experience runaway temperature under oxygen excess, so the ultimate outcome is inevitably sulfur ignition.

The concepts of bed temperature rise and ignition are different

Bed fire is caused by excess oxygen first triggering the combustion of ferrous sulfide and then that of sulfur. Ferrous sulfide comes from the iron-based catalyst or within the system. Spontaneous combustion of large amounts of ferrous sulfide causes a rise in temperature.

One phenomenon, one essence; the two definitions must not be confused

Fly temperature and bed fire are not the same thing; fly temperature can be caused by bed fire or by other factors, such as changes in the composition of acidic gases.

A bed fire inevitably leads to a spike in temperature, but a spike in temperature does not necessarily mean a fire. It could also be a vigorous oxidation reaction of iron sulfide. It causes a rapid rise in temperature, but overall, an excess of oxygen is the main cause and should draw our attention.

The reason for the rapid temperature rise in the bed is the excess oxygen in the process gas, which causes ferrous sulfide, carbon deposits, and even sulfur to ignite, leading to a swift increase in temperature.

The so-called intense oxidation reaction of ferrous sulfide is, in essence, the spontaneous combustion of ferrous sulfide, and spontaneous combustion means catching fire. I can think of no other reason besides fire that could cause a sharp rise in temperature

Bed temperature surge and bed ignition are two different concepts; ignition refers to combustion, while temperature surge does not necessarily involve combustion. For example, if the catalyst is too active, intense exothermic reactions can also cause temperature surge. Therefore, it is necessary to use catalysts with lower activity (such as in the isothermal adiabatic hydrogenation process for catalytic coking dry gas).

Bed temperature spike is different from bed ignition; a bed temperature spike refers to a rapid increase in bed temperature. There are various reasons for such changes: (1) The reaction between hydrogen sulfide and sulfur dioxide is exothermic, and if its concentration in the converter is high, the temperature can also spike. (2) Leakage inside the high-temperature mixing valve allows high-temperature flue gas to enter the reactor, which can also lead to a rise in temperature. (3) Iron sulfide and peroxide combustion can cause excessive temperature rise in the bed. Bed fire occurs only in case (3).