Regulation of diesel distillate yield through catalytic fractionation
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For catalytic fractionation of diesel, operators generally use two methods: 1. Keep the intermediate circulation rate and the heat removed constant, and adjust the amount of diesel distilled by controlling the opening degree of the diesel outlet； 2. Keep the opening of the diesel distillation outlet constant, and control the distillation volume by adjusting the intermediate temperature. Which of these two methods has a lesser impact on production?
The diesel flow rate is primarily controlled by adjusting the amount of material returned to the tower in the middle section and the heat exchange amount, and this is ultimately reflected in temperature: a higher temperature results in a greater flow rate, while a lower temperature leads to a smaller flow rate.
Adjust the intermediate temperature to control the distillate volume
Adjusting the opening of the diesel distillate outlet has a much greater impact on the entire tower. Generally, adjusting the temperature is used; this can be considered fine-tuning. The diesel distillate outlet and the mid-stage return to the tower are rarely operated
The quality of light diesel is primarily controlled by adjusting the gas phase temperature of the trays below the extraction layer, by changing the heat taken from the middle and lower sections of the reflux stream (including the reflux volume and reflux temperature). If necessary, the opening degree of the extraction port as well as the discharge of heavy fuel can be adjusted. Priority should be given to adjusting the reflux temperature in Unit 1. Adjusting the flow rate will have a significant impact on the quality of gasoline.
In catalytic fractionation towers, diesel is generally extracted in its entirety, so it is not possible to control the amount of distillate produced. The circulation volume remains constant during production, and adjustments are made by adjusting the temperature of the material returning to the tower; if adjustments cannot be made through this temperature control, then the return flow rate is used for adjustment. Principle: Temperature first, then flow rate.
Adjusting the temperature is better than adjusting the valve opening, which allows for a more stable operation of the distillation tower.