Why, with a lower reprocessing ratio and a higher temperature of the oil and gas entering the tower, is the amount of heat brought into the distillation tower still low?
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I read in the book \"Catalytic Cracking Processes and Engineering\" that when changing from a diesel production scheme to a gasoline production scheme, the reprocessing ratio decreases, which results in less heat being introduced into the distillation column. At the same time, the temperature of the reaction gases entering the column rises, leading to an increase in the amount of gasoline produced. This in turn increases the proportion of heat taken away from the oil slurry and the top reflux. How should this be understood? ? ?
I’m a primary school student and don’t quite understand the meaning of this sentence. If heat is reduced in the fractionation tower, shouldn’t the temperature of the oil and gas at the inlet be lower? ?
In the gasoline scheme, the reaction temperature needs to be increased (I recall that for the diesel scheme the temperature is controlled at 480 to 490 degrees, while for the gasoline scheme it’s 500 to 515 degrees); therefore, the temperature of the oil and gas entering the fractionation tower increases without a doubt. The decrease in the heat supplied to the distillation column is due to a reduction in the reprocessing ratio. A lower reprocessing ratio means that less material (reprocessed oil and slurry) enters the lift pipe from the distillation column. This reduced amount of material is in liquid form at around 350 degrees inside the distillation column, but once it enters the lift pipe it turns into a gas at around 480 to 500 degrees, carrying away a large amount of heat from the reaction system. Therefore, a lower reprocessing ratio results in less heat being supplied to the distillation column.