The fluidization in the pre-lift section of the lift pipe is abnormal, with large fluctuations in pressure difference and density, as well as large fluctuations in reaction temperature
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Recently, the fluidization in the pre-lift section of the reactor’s lift pipe has been poor, with large fluctuations in density pressure differences. When the density increases, the reaction temperature drops; when the density decreases, the reaction temperature rises. Additionally, there are also large fluctuations in the pressure difference across the secondary valve. As the density in the pre-lift section increases, the pressure difference across the secondary valve decreases. It’s not clear whether the pressure difference across the secondary valve changes first or the density in the pre-lift section does. Is it the poor fluidization in the inclined tube section or the poor fluidization in the pre-lift section? Are there any good solutions?
Is there a problem with the boosting medium? It would be worth checking, and also what type of device it is
If the lifting medium is steam, check whether there are any changes in the pressure, temperature, and flow rate of the steam. Analyze the composition of the catalyst to see if there isn’t too little fine powder. Manually operate the valve and observe the situation, as well as adjust the differential pressure between the two vessels and their inventory levels. Based on personal experience, this problem is usually caused by poor fluidization within the valve or within the regeneration inclined tubes
It might be that the regenerative spool is not flowing properly, causing the lining to fall off.
Reply to 2#: Do something you’ve never done before, FDFCC. Recently, the feed volume has been low; for a plant with a capacity of 800,000 tons, the current feed rate is less than 40 tons per hour
Reply to 3# sky5778416: Thank you for the help. Things are better when the regenerator has a high storage capacity; in that case, the pushing force of the valve doesn’t fluctuate much and remains high, at around 60 kPa. However, this situation still occurs with the 800,000 tons/year regenerator and a stock of 75 tons; during the previous cycle, when these parameters were considered, such obvious problems were not detected. Would it be better to adjust the flow rate of the steam used for fluidizing the inclined tubes? Since the operation started, the steam flow for fluidizing those inclined tubes has been at full capacity on the bypass line – is that too much?
Our unit has shown similar performance over the past six months or so: the pre-heating stage works normally, but the pressure drop during the subsequent stage is really poor; at its lowest, it dropped to single-digit levels. However, the unit operates fairly well overall. Currently, the pressure drop fluctuates quite a bit – it’s around 24 under normal conditions, which is already quite low, while it ranges from 15 to 35 during fluctuations. The reaction temperature and pressure also fluctuate accordingly, with temperature variations of up to 5 degrees. At present, we rely on adjusting the steam flow to control these fluctuations; as for the exact method of adjustment, it seems to depend on luck, as there’s no pattern to it. Nevertheless, this approach helps to reduce temperature fluctuations. Our unit is also worth 800,000 units, and it’s of the same type with parallel arrangement. The current processing capacity is 78
What is the opening degree of the regenerative slide valve upstairs? Does the density of the regenerative inclined tubes fluctuate?
Personally, I think it’s caused by poor fluidization of the regenerated inclined tubes; it might be due to a blockage in the air return line for those inclined tubes
If the medium used for lifting is steam, check whether there are any changes in the pressure, temperature, and flow rate of the steam; make adjustments accordingly. Would it be better if the steam used for fluidizing the inclined tubes is adjusted as well? Since the operation started, the steam used for fluidizing the inclined tubes has been flowing at full capacity through the bypass line – is that too much?