Purpose of catalytic re-refining of oil
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I would like to ask fellow sea professionals: what is the purpose of catalytic cracking and re-refining (re-reacting) oil? ? Did increasing the reprocessing amount improve the yields of dry gas and liquefied gas? (under the condition that all other factors remain unchanged)
Provides recycled coke and gas, steam, and diesel components generated from reprocessing
At a certain overall conversion rate, the recycle ratio reflects the one-pass conversion rate, and it decreases as the one-pass conversion rate increases. If the cracking conditions are relaxed, the one-pass conversion rate decreases and the reprocessing ratio increases, which can increase diesel yield and decrease gasoline yield; however, the overall light oil yield still increases. On the other hand, the quality of light diesel has also improved, with its cetane number increasing and its freezing point decreasing. The biggest negative effect of increasing the reprocessing ratio is the increased heat required for reaction and distillation, leading to higher energy consumption. This also limits the production capacity of the device, requiring a reduction in output as a consequence. Of course, for heavy oil catalysis, excess heat is the main problem, as the heavy cyclic hydrocarbons present in reprocessed oil and slurry are difficult to crack. If the oil slurry is not removed, the coking rate will **increase**, and it will also be difficult to control the solid content of the oil slurry; therefore, an operation with a high recycle ratio is not advisable. Moreover, the light oil yield will not decrease significantly, and the amount of gasoline will actually increase.
Re-refined oil is a side-product from a distillation column whose boiling range is similar to that of the catalytic cracking feedstock, located between heavy diesel and slurry; it has properties that are heavier than those of the feedstock oil. The level of the reprocessed oil reflects the degree of reaction depth. This device is generally used to control the amount of material returning to the lift column through distillation; everything else is the same as before
Additionally, when the properties of the raw material are relatively light, re-refining oil is carried out to maintain the thermal balance of the regeneration system.