Recycle volume of fractionated slurry back to the tower
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Is it true that the circulation volume of the slurry returning to the tower should be as large as possible? What are the negative effects of being too large on other systems?
The reboiler is used to control the temperature at the bottom of the tower; this control is based on the temperature at that location. Generally, the temperature at the bottom of the tower is around 345 degrees, with an upper limit of no more than 350 degrees, in order to prevent coking at the bottom of the tower and in the pipelines. If the reboiler operation is excessive, the temperature at the bottom of the tower becomes too low, which hinders heat balance throughout the tower, results in reduced yields, and also affects the absorption and stabilization systems
The downward flow in the tower should be controlled based on the temperature at the bottom of the tower; if it is too high, it will affect the thermal balance of the entire tower. An increase in the amount of slurry discharged outward will also impact the efficiency of heat recovery.
The return of oil slurry from the distillation tower is primarily used to control the bottom temperature. If this adjustment is too large, it will affect the circulation volume in the tower, thereby undermining the effectiveness of the catalyst used for washing. Therefore, in order to maintain an appropriate amount of slurry returning to the tower, specific requirements are set by the petroleum industry. Another purpose is to prevent coking at the bottom of the tower; the return of slurry to the tower is one means of achieving this, along with the use of steam for stirring at the bottom of the tower.