The density of light diesel remains high; how should operations be adjusted?
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Catalytic fractionation of light diesel results in a high density; therefore, the amount of material circulating in the middle stage has been increased, and the temperature at the distillation outlet has also decreased. The lower distillation outlet has been completely closed, and only the upper distillation outlet is in use – yet the density still doesn’t decrease. A small amount of material is being sent back to the tower in the second middle stage. Could this be the cause, i.e., the transfer of heavier components upward? I hope experts can help!
Reply to 1# zsdfta: Reasons for the high specific gravity and adjustment measures: 1. The diesel distillation range is high; lowering the distillation temperature can reduce the amount of distillate； 2. Influence of raw material properties; adjust the properties of the raw materials ； 3. Influence of reaction depth: A higher reaction depth, such as a larger reprocessing ratio or higher reaction temperature, leads to an increased content of aromatics with 3–5 rings in diesel; it is necessary to adjust the reaction depth appropriately ；
First, you can try to increase the flow rate while ensuring the quality of other products, and control so that the heavy components do not rise to the level of light diesel. If that doesn’t work, you can analyze the reasons and, following the analysis provided by Lin above, adjust the reaction conditions and the properties of the raw materials accordingly.
Is it necessary to control diesel density for catalysis? We have little control over it. The gasoline components can be pushed downward to reduce the density of diesel ；
While ensuring product quality, try to increase the amount of reflux in stage 2 in order to prevent an increase in the proportion of heavy components; then check the yield of light diesel. If the yield is low, increase the flow rate of the main steam at the bottom of the tower accordingly
What technical approach? This is a prerequisite
Has there been any change in the sampled color? Could it be that heavy oil has leaked into the heat exchanger?
If the boiling range remains stable and there are no fluctuations in operation. It should be the influence of the properties of the raw materials. Try changing the raw materials