Relationship between viscosity in the pyrolyzer and dilution steam pressure
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While studying * yesterday, I came across this statement: If the viscosity in the cracking furnace is too high, the pressure of the dilution steam can be reduced appropriately. I don’t know what it means; please explain it to me, expert. Also, today I saw someone say that among the methods to reduce the viscosity in the pyrolysis furnace, it is best not to reduce the extraction of pyrolysis diesel, as the extraction of pyrolysis diesel is intended to remove the monomeric polymers from the distillation section. I’m not quite sure what this means; could you please help? Thank you so much. (I’m learning *pyrolysis and need to ask for a lot of advice from everyone.) . Hehe)
Doesn’t the pre-depropanization process have a viscosity reduction tower? There shouldn’t be such a thing as cracked diesel. Only light and heavy fuel oil, as well as sludge oil. The pressure of the diluted steam increases, while the circulation rate of the quench oil remains unchanged. The temperature at the bottom of the gasoline distillation column rises; due to the increased pressure, the evaporation temperature of DS also increases, and accordingly, the heat exchange temperature of the quench oil in the DS generator rises as well. Lowering the dilution steam pressure has the opposite effect.
Reply to 2# Front-line staff: The pressure of the diluted steam increases, while the circulation volume of the quench oil remains unchanged. As a result, the temperature at the bottom of the gasoline distillation column rises. Due to the increased pressure, the evaporation temperature of DS also increases, and accordingly, the heat exchange temperature of the quench oil in the DS generator rises as well. Lowering the dilution steam pressure has the opposite effect. This sentence isn’t very clear. I understand that as the DS pressure increases, its boiling point also rises. But then it says that the heat exchange temperature of the quench oil in the DS generator increases accordingly; does this mean that if the DS pressure rises, in order to ensure gas production it is necessary to artificially raise the temperature of the quench oil, which is why the quench oil temperature becomes high? Similarly, with low DS pressure, is the quench oil temperature artificially reduced to decrease viscosity? I’ve just started learning about pyrolysis and don’t know much about these things yet. . .
The issue with the original poster’s question lies not in the viscosity of the cracking furnace, but rather in the viscosity of the quench oil. There are several ways to adjust viscosity, and it’s necessary to analyze each specific situation individually
Reply to 4# whq107: It was completely a typo; please don’t mind it, haha. It does require a detailed analysis; I just saw such a statement in the materials and wanted to understand what the relationship between them is. Hehe.
In my opinion, the pressure in the DS unit has little effect on the viscosity of QO; the main influencing factors are the composition of the raw materials, COT, as well as the bottom and top temperatures of the quench oil tower. It is the amount of pyrolyzed diesel or light and heavy fuel oils that determines the output.
The relationship between diluted steam and the viscosity of quench oil is minor; however, during normal production, it is not possible to control the adjustment of raw materials through operational procedures. Therefore, reducing the pressure of the diluted steam is used to lower the temperature of the quench oil, thereby helping to reduce the temperature in the oil wash tower as a means of regulation. (The saturation temperature decreases as pressure decreases.)
Can it be understood that, with all other conditions remaining constant, reducing the pressure of the dilution steam leads to a corresponding decrease in its saturation temperature; as a result, more heat from the quench oil is removed through the dilution steam, which in turn lowers the temperature in the tower and reduces the viscosity!
Increasing the oil circulation volume in the disk can lead to low DS pressure, which in turn facilitates the intrusion of Qo into the DS system
Firstly, reducing the DS pressure can lower the temperature at the bottom of the oil washing tower; subsequently, a decrease in the dilution steam pressure leads to an increase in the residence time. At the same time, a decrease in the temperature at the bottom of the oil washing tower and a decrease in the dilution steam pressure create a vicious cycle (in the absence of any other heat source)
Reducing the production of pyrolyzed diesel will cause the heavier components in the quench tower to rise, and over time coking will occur