The significance and role of recycled oil in catalytic cracking, as well as the connection between the reaction and distillation units
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Could that expert explain the significance and role of reprocessed oil in catalytic cracking, as well as the interconnections and interactions between the reaction and distillation units? ! ! ! Thank you so much! ! !
The following is a summary I’ve made on my own for discussion purposes; feel free to add anything or point out any errors, hehe. Functions of re-refining oil: 1. Re-refined oil is fed into the lift pipe for re-refining, thereby increasing the yield of the product. Especially when increasing diesel production, the reprocessing ratio can be increased. The disadvantage is that the reprocessed oil contains a high amount of aromatics, making it difficult to crack, and it tends to form coke, which affects the processing capacity of the plant. 2. Return the reprocessed oil to the tower to provide liquid-phase reflux for the lower trays of the tower; otherwise, the trays will dry out ； It assists in regulating the liquid level at the bottom of the fractionation tower; if the slurry circulation is interrupted, increasing the amount of reprocessed oil fed back to the tower can indirectly help the slurry to rise back up the tower.
Adding another point on top of what’s mentioned on the 1st floor: re-refining oil also serves to remove heat, that is, it helps to balance the heat distribution between the reaction process and distillation. How to understand this specifically: Recycled oil can be regarded as a product resulting from one reaction; its crackability has been **reduced**. Therefore, when recycled oil at a temperature of over 300 degrees is fed into a reactor at around 500 degrees, it is heated to nearly 500 degrees before being sent back to the distillation tower, thereby serving the purpose of heat extraction. (My personal understanding; it’s not necessarily correct, just to aid explanation.)