What are the reasons for salt buildup at the inlet of the top circulation pump, and how can it be adjusted and addressed?
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What are the reasons for salt buildup at the inlet of the top circulation pump, and how can it be adjusted and addressed?
When scaling occurs, the number of times the top circulation pump needs to be emptied increases significantly, and there is severe overlap between gasoline and diesel. The reason is that during the reaction process, nitrides in the crude oil produce NH3; at lower temperatures, ammonia and hydrogen chloride form salts, which then crystallize out at those low temperatures. Treatment: Perform water washing of the trays to remove salts, reduce the reaction volume, direct crude gasoline and diesel to the unqualified stream, stop the top circulation pump, and pay attention to the water analysis of tower washing water as well as changes in tray pressure drop.
If only salt buildup occurs at the inlet of the top circulation pump, and there are no signs of salt buildup on the trays of the distillation tower, it is not necessary to wash the distillation tower; simply washing the top circulation pump is sufficient
The temperature at which the top circulation pump extracts the liquid is much higher than the temperature at the top of the tower. In my opinion, if salt builds up at the pump inlet, the condition of the tray sections will certainly not be much better
Are there any process adjustments to avoid this phenomenon?
While ensuring that the crude gasoline meets the required standards, strive to control the temperature at the top of the high-pressure distillation tower, and adjust the amount of ammonia injected at the tower top as appropriate
If it is only the pump flow rate at the top that fluctuates significantly, it is not necessarily due to salt accumulation at the pump inlet; it could also be caused by uneven distribution of the heat load in the distillation tower, insufficient load at the top, water carried in by the cold reflux, or a clogged filter at the pump inlet
Is continuous online water injection provided to the pipeline at the top of the tower?
Control the temperature at the top of the tower; a temperature range between the salt formation temperature and the dry point of gasoline is sufficient. Salt formation occurs mainly when the temperature at the top of the tower is low, causing ammonium chloride to precipitate and thereby increasing the pressure drop in the tower.