Catalytic cracking
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1 Does an increase in the weight of the raw material components affect the extraction temperature for re-refining oil? Assuming all other conditions remain unchanged. I’ve always had a vague understanding of the thermal balance in catalytic cracking distillation columns, especially regarding primary and secondary refluxes, internal recirculation, and top circulation. Which tray levels can their backflow affect? How should it be understood? Let me give an example: for instance, could my actions at No. 1 Middle School affect No. 2 Middle School, or could someone else influence the temperature? How can we understand this heat equilibrium transfer? I hope experienced professionals can explain the underlying principles in a simple and easy-to-understand manner I have just started working with catalysis, and I feel that it is somewhat different from what I learned about hydrogenation distillation columns before. In those columns, the reflux action at the top of the column can potentially affect the bottom of the column. Can’t the fractional distillation tower of catalytic cracking have any impact?
You should find a master craftsman in the workshop; he can explain it to you. It might not be explained clearly here
This can’t be rushed; by practicing every day, you’ll understand it all over time. As the properties of the feedstock become worse, the amount of oil that needs to be reprocessed increases. If this amount isn’t increased, the liquid level in the reprocessing tank will rise, which requires an increase in the amount of oil sent back to the distillation tower... This results in high liquid levels throughout the lower part of the distillation tower, which is the least economical approach ； Therefore, once it is detected that the properties of the raw material have changed, the reaction unit must promptly adjust the reaction conditions: by increasing the catalyst circulation rate, enhancing catalyst activity, raising the reaction temperature, etc ； A competent operator in a reaction unit will keep a close eye on the liquid level in the catalytic fractionation re-refining tank to adjust the operations accordingly. In the gas or gasoline mode, maintain a low level in the recycle tank; in the diesel mode, maintain a high level in the recycle tank.
We use the upward flow in the tower to control the gas phase temperature at the first tray; no matter how the reflux at the upper part changes, by adjusting the upward flow in the tower, the temperature of the first tray remains unchanged
At the top of the tower, the heat taken away by the first and second stages must be equal to the heat applied at the bottom of the tower in order to achieve balance; if one of the reflux streams is increased, the other reflux streams will definitely be affected
With the raw material weight increasing, the reaction temperature remaining unchanged, and the extraction temperature of the reprocessed oil staying the same, the amount of reprocessed oil will increase, resulting in an elevation of the liquid level in the reprocessed oil tank. The thermal balance in distillation can be understood as a state of equilibrium between the heat entering the distillation column and the heat removed from it. If too much heat is taken away by one section of the reflux stream, while the temperature and volume of the oil and gas entering the column remain essentially unchanged, then in order to maintain the thermal balance of the entire column, less heat must be taken away by the other sections of the reflux stream. Of course, the amount of heat taken away by each section of the reflux stream also needs to be allocated appropriately based on the quality requirements of the product.