Poor drainage from the bottom of the distillation tower
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Guys, the extraction from the bottom of the distillation tower isn’t going smoothly! It is estimated that there is a large amount of catalyst at the bottom of the tower, resulting in coking! Is it possible to return the slurry to the tower in order to add some diesel to the bottom of the distillation tower for dilution?
This post was last edited by xutj01 on 2010-7-12 06:22. 1. Generally, diesel is not added; instead, crude oil is used. A higher temperature of the feed oil prevents vaporization, thus having a lesser impact on the thermal balance of the distillation tower. 2. Diesel is added; due to the low temperature and the heat absorbed during vaporization, the operation of the distillation tower experiences significant fluctuations. Recovery time is long. 3. Generally, no diesel is added, but it is still possible to \"add a portion of diesel to the bottom of the distillation column by returning slurry downward in order to dilute it.\" 4. “There is coking!” ”The bottom temperature of the distillation tower should be adjusted, and scale inhibitors should be added. 5. The issue of \"an excessive amount of catalyst at the bottom of the tower\" should be analyzed to find a solution.
Diesel cannot be top-uped; high temperatures will cause it to vaporize, leading to vacuum in the slurry pump. Rerefined oil or crude oil can be added to the slurry flowing back to the tower, thereby improving the efficiency of the slurry in washing the catalyst and increasing the amount of slurry discharged. Increase the dosage of the slurry scale inhibitor. Optimize the operation of the two units; if there is severe agent leakage, a solution must be found.
It is recommended that the original poster’s first step be to switch the pump, and check whether there are any coke deposits blocking the inlet filter of the pump that is currently in operation. If not, then: 1. Analyze the solid content or ash value of the oil slurry at the bottom of the tower to determine whether coking of the oil slurry has occurred due to significant loss of catalyst. 2. Increase the dosage of the slurry scale inhibitor appropriately. 3. Check whether the stirring steam and stirring slurry at the bottom of the tower are in normal operation; if not, start them up, and if they are already in operation, increase their dosage appropriately. (When putting it into operation or increasing the input volume, it is necessary to monitor the pressure and temperature loads across the entire tower to prevent overpressure in the tower and the catalyst from reaching the upper trays.) 4. Feed raw oil through the emergency bypass to enter the tower and dilute the slurry. Personal opinion, for reference only!
It may be caused by coking at the bottom of the tower; try adjusting this by increasing the amount of stirring slurry or steam at the bottom of the tower