Vapor equilibrium line of the feed oil buffer tank in the coking unit
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The gas-phase equilibrium line of the feed oil buffer tank in the delayed coking unit is connected above the wax oil collection tank of the distillation tower. What is the function of this pipeline? How does the medium flow within the pipeline?
The vapor equilibrium line is connected to the evaporation section of the wax oil collection tank in the distillation tower, thereby balancing the pressure at the top of the feedstock buffer tank with the pressure in the evaporation section of the wax oil collection tank in the distillation tower; hence it is called an equilibrium line. It serves to balance the pressure in the raw material buffer tank and the flow rate of feed in the pipelines, thereby ensuring stable feeding to the raw material oil pump. When the liquid level in the raw material buffer tank becomes too high or even overflows, the fluid can flow through the balance line to the evaporation section of the distillation tower; the oil and gas in the buffer tank can also reach the distillation tower via this balance line.
Currently, the outer wall temperature of the balance line is around 300, while the temperature at the top of the buffer tank is around 150. Does this mean that the oil and gas in the fractionation tower have reached an equilibrium state? What causes this?
Due to the effect of the balancing pressure, the pressure in the buffer tank is brought into balance with that in the wax oil collection tank at night; it also serves a overflow function, allowing the raw material to flow over into the collection tank in case the buffer tank overfills.