It is difficult to control the quality of distillation diesel when 500,000 units are used for catalytic startup
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After startup, the reaction feed rate was 60 tons, the reaction pressure was 166 KPa, the distillation top pressure was 124 KPa, the diesel extraction temperature was 175°C, and the top temperature was 108°C. An unstable intermediate stream volume required additional diesel to be added. Interrupts: 140; amount of slurry returning upward: 94; amount used for cooking: 43. Please advise
The water in the middle section doesn’t drain out; try increasing the top temperature to reduce the amount of water in that section, and remove all the water through the distillate at the top of the splitter tower. This way, the quality of diesel can be better controlled.
I feel there’s an issue with your heat distribution: could you increase the amount of heat exchanged between the upper and lower towers, enhance heat extraction through slurry circulation, and reduce interruptions in heat extraction? Increase the amount of oil slurry sent back to the tower to 150 t/h, reduce the interruption amount to around 80 t/h, and appropriately raise the top temperature to about 115°C.
I have here some fractionation data with a feed rate similar to yours: top pressure of 0.095； Diesel extraction at 237 degrees ； Top temperature: 114 degrees ； Mid-stage return to tower volume: 63, mid-stage return to tower temperature: 206 degrees ； The slurry returns at 190, and descends at 70.
First, resolve the issue of unstable mid-range flow; only then can the diesel topping up be stopped. I don’t know what the diameter of the tower is or what the opening ratio is. Based on the current data, the temperature distribution is acceptable; could the poor measurement in the middle section be due to liquid leakage from the tray? The issue can be resolved by gradually reducing the amount of slurry returning to the tower, thereby increasing the gas load on the middle trays and preventing liquid leakage; this will work once the diesel feed is stopped.