Issues with the regenerative spool valve
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Recently, the opening degree of the regenerative slide valve has suddenly decreased, while the reaction temperature remains unchanged. The on-site opening degree is similar to what is displayed on the DCS; I’m not sure what the cause is. Seeking help from experts, thank you!
Have there been any adjustments to the regeneration pressure in your systems recently? Is the reaction pressure lower than before? Is the regeneration pressure a bit higher than before? Or perhaps the regeneration temperature is higher than before; has the amount of quenching medium injected been reduced or discontinued? Has the preheating temperature of the raw materials increased a bit? And so on. Production is ever-changing, and the reasons for this can also be diverse.
Right! There are many influencing factors; changes in feed rate, raw material preheating temperature, the amount and composition of the terminator, steam temperature in the reaction zone, and the pressure difference between the two vessels can all cause this phenomenon! Each one should be checked individually!
We suspect that the valve plate is worn, or the valve passage is damaged.
This possibility certainly exists as well; there are quite a few reasons that could lead to it
Has the processing capacity decreased? Has the bed temperature of the regenerator increased? Has the preheating temperature of the crude oil increased? In the MIP process, is the amount of terminator used reduced?
There are various influencing factors; by eliminating them one by one, it’s unclear whether any adjustments were made to your device – otherwise it’s impossible to determine anything.
If such a situation arises suddenly without any adjustments to other factors； Then it must be caused by wear of the regenerative spool valve plate or erosion of the track.
You can assess an accident (let’s call it that for now) from the perspective of thermal equilibrium; if there is no adjustment in production, it indicates that the amount of heat supplied by the catalyst remains unchanged, the valve opening size decreases, but the catalyst flow rate through the valve (not the flow cross-sectional area) stays the same； The causes can be found in the pressure balance of the two-device system and the valve body. If the operation has been adjusted, there’s no need to doubt the valves; the materials and manufacturing standards are still excellent today.