How to determine the reaction depth of a section of riser tube at both ends

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One core of the riser at both ends is that a fatal weakness of conventional catalytic cracking based on the staged reaction principle is that the reaction is carried out in the same reactor regardless of the difference in properties of the fresh raw material and circulating oil, resulting in vicious competition between adsorption and reaction. The oil slurry that is difficult to crack is easy to vaporize and adsorb, while the fresh raw materials that are easy to react are difficult to vaporize and adsorb. It can be said that the two are incompatible. In addition, different fractions require different ideal reaction conditions, and it is difficult to select conditions when mixed together. The so-called segmented reaction is to allow different fractions to react in different places and conditions to eliminate mutual interference. In the two-stage riser catalytic cracking, only fresh raw materials are fed into the first stage riser. The target product is extracted from the interstage as the final product to ensure the yield and quality. The oil slurry and refining oil (circulating oil) that are difficult to crack enter the second stage riser separately. In this way, the interference of oil slurry is eliminated for fresh raw materials. * * Increased effective contact between reactant molecules and catalyst active centers ； For oil slurry, there is no longer competition with fresh materials and previously produced gasoline and diesel, and the reaction opportunities are also limited. * * Increase, thereby increasing the depth of raw material conversion and improving product distribution. In addition, in order to reduce the olefin content and sulfur content of gasoline, part of the crude gasoline fraction can enter the appropriate part of the second stage riser for upgrading, and the loss of the target product can be reduced by optimizing reaction conditions according to production requirements. In actual operation, it seems difficult to determine how much raw material is cracked in the first stage and how much is left for the second stage. Just looking at the liquid level at the bottom of the tower and the liquid level of the recycled oil does not seem to be able to better utilize the advantages of the risers at both ends.