External heat exchanger
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The external heat exchanger of the regenerator in our plant has two types of air: one for fluidization and one for lifting. There were two instances when fluidization became difficult suddenly, preventing heat extraction; the density of the catalyst was very high, approaching 700, while the density in the return pipes was extremely low, preventing the catalyst from flowing down through the inclined tubes. It took several hours of repeated adjustments to the flow rates of the fluidization and lifting air before fluidization could be restored to normal. What’s going on? This post was last edited by Shuichangshou on 2009-3-30 16:36.]
Are there any before-and-after comparison data and reasons for difficulties in fluidization? Suggestion for addition.
Is your external heat exchanger of the external circulation type or the recirculation type? It is necessary to clarify the structural type before a diagnosis can be made.
It’s hard to judge simply by saying that; it’s recommended to provide detailed information about the process and data from that time!
Is it a downstream or upstream type? Are all the booster fans functioning properly at the beginning?
I didn’t quite understand it, but its structure is similar to mine; it seems to be of the upward-flow type, with the catalyst located on the outside for heat extraction and flow occurring from bottom to top inside
Your external heat exchangers should all be in a fully mixed series configuration, right? Is it a clog in the catalyst lift pipe?
If it is controlled by air pressure, with the catalyst flowing from top to bottom, I think it might be like this: there should be a certain distance between the lift air and the fluidization air; is the slope of this section of pipeline small? If so, it’s possible that the catalyst in this section has become compacted. If the density of the return air is low, then it seems that you are simultaneously turning on both the lift air and the fluidization air. At that point, has the amount of heat removed already reached its maximum value? The adjustment should involve reducing the amount of lift air, while repeatedly turning the fluidization air on and off. This is just my personal opinion; I’m not sure if it’s correct
Based on what LZ said, it seems that heat extraction from the outside is causing a blockage; this can be indicated by the bulk density. I wonder what the opening degree of the external heat extraction slide valve is at this time? Additionally, does the dense-phase temperature of the regenerator also decrease at the same time? If so, it is likely due to an obstruction caused by external heat extraction; in such cases, adjusting the ratio by supplying air multiple times with fluidized air can help to clear the obstruction. Usually this approach works. If that doesn’t work, then the material inside needs to be removed, haha
The fluidization is definitely abnormal. Factors affecting fluidization include issues with external and internal equipment, as well as fluctuations in the amount of air supplied. The specific parameters of these changes are unknown
There is an inclined tube between the air-controlled external heat exchanger boost air and the fluidization air; when it stops operating and then starts up again, blockages can occur. In such cases, the adjustment points on the inclined tube can be adjusted, or the supply air can be turned on and off repeatedly to gradually loosen the catalyst in the inclined tube. Once fluidization occurs, flow will be restored immediately.
1. Temporary abnormality in external fluidization occurs due to insufficient power or excessive resistance. . . Please look for the pressurized air. . . 2. It seems that, depending on the circumstances, leakage from somewhere outside may have caused localized caking of the catalyst. . . Please conduct a check on each group and each wire based on the external retrieval status. . . :lol
Is there any short circuit in the catalyst fluidization?