Dry point of catalytic cracking fractionated crude gasoline?
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In a catalytic cracking unit, when the steam used for lifting or stripping in the reaction section is increased, how does the dry point of the crude gasoline obtained through distillation change under normal conditions? Will it get bigger or smaller? Why?
The dry point control of crude gasoline is primarily achieved through the operation of the distillation tower, and it is controlled based on the vapor pressure and temperature at the top of the tower. Relatively speaking, temperature adjustment is much more sensitive than adjustments to the vapor pressure; moreover, the amount of steam used in the reaction section only affects the vapor pressure at the top of the distillation tower, so its impact is minimal. Under normal conditions, as the steam volume increases, the oil vapor partial pressure decreases; with the top temperature remaining constant, the dry point of gasoline rises.
The main factor affecting the catalytic unit is the reaction temperature; simply speaking, the effect of stripping steam or pre-raising steam on the dry point of gasoline is not significant, and the distillation system can be adjusted to address this.
The means for controlling the dry point of catalyzed crude gasoline are primarily achieved through the regulation of the temperature at the top of the distillation column. The temperature at the top of the distillation column responds much more sensitively to adjustments than does the vapor pressure of the oil and gas mixture; the amount of steam used in the reaction section has little impact on the dry point of the crude gasoline.
If the distillation conditions remain unchanged, there should be no significant change in the dryness level; it’s just that the amount of water in the reflux tank increases
It is also necessary to consider the operating parameters at the top of the fractionation tower to confirm, such as temperature, pressure, and top cycle reflux. If these factors remain unchanged, increasing the dry point of the stripping steam gasoline will rise.
As the vapor pressure of oil and gas decreases, the dry point of gasoline increases, all other conditions remaining constant
The dry point of gasoline is primarily controlled by the reaction temperature, the reflux temperature at the top of the distillation column, and the amount of cold reflux. The amount of steam used in the reaction process has little impact on the dry point of crude gasoline. Meanwhile, the amount of terminator used and the choice of medium also exert a certain influence on the dry point
As steam increases, the vapor pressure of oil and gas decreases, and the dry point rises. Conversely, it decreases, but that is theoretical; in practice, significant changes in the stripping steam are required for it to have an effect on the dry point of gasoline. Generally, there are no problems. However, care must be taken if the terminator is switched from gasoline to water.
With all other operating conditions unchanged, increasing the reaction portion or the amount of stripping steam raises the dry point of the crude gasoline obtained through distillation. That is, it becomes larger. Since the partial pressure of oil and gas decreases relatively, the dry point rises.
Increasing the gas vapor, with all other conditions remaining unchanged, raises the dry point of gasoline slightly
If the steam volume is increased, while the pressure and temperature at the top of the tower remain unchanged, the vapor pressure of oil decreases and the dry point rises; however, this effect only occurs when the steam volume is very large
Generally, as the steam volume increases, the partial pressure of oil and gas decreases accordingly; this makes it easier for the oil and gas to vaporize. As a result, the composition at the top of the tower becomes heavier, leading to an increase in the dry point of the crude gasoline.
Theoretically, increasing the amount of stripping steam reduces the vapor pressure of oil and gas, thereby raising the dry point of gasoline. But I think it’s really difficult to quantify the impact with data.
Increasing the amount of stripping steam means that other conditions remain unchanged, right? However, a higher amount of stripping steam helps to remove the oil and gas components from the raw catalyst, but there are also economic considerations involved.
With the total pressure remaining constant, if the vapor pressure of oil decreases, will the dry point also increase? How should I understand this?