Seeking help with distillation column operation
Thread Content
The diesel hydrodesulfurization distillation column uses steam as the stripping medium; when all other conditions remain constant, increasing the amount of stripping steam reduces the vapor pressure of the oil and gas, thereby lowering the boiling point of the product at the bottom of the column and causing a decrease in the temperature there. At this point, will the flash point of the diesel product at the bottom of the tower decrease accordingly? In other words, at the temperature resulting from the drop in bottom temperature, is it necessary to raise the bottom temperature back to its previous level in order to ensure that the flash point meets the requirements? How should we understand the principle behind this part?
The temperature at the bottom of the tower should increase, right?
The boiling point of the product at the bottom of the tower decreases, causing the temperature at the bottom to drop. In actual operation, the bottom temperature indeed decreases
In a tower that uses water vapor for stripping, the flash point has little relation to the bottom temperature of the tower; what matters is the temperature of the water vapor and the temperature of the oil entering the tower. If the temperature of the steam used for stripping remains constant along with the temperature of the oil, increasing the amount of stripping steam will lower the bottom temperature of the tower, and as a result, the flash point of the product at the bottom of the tower will increase – there is no need to consider the bottom temperature
Generally speaking, changes in the density of the components at the bottom of the tower are directly reflected in temperature changes. The components are light, and the bottom temperature is low. But in the case of increasing the amount of stripping steam (with the steam temperature being 40 to 50 degrees higher than the bottom temperature), the bottom temperature of the tower decreases. I’m not sure why the flash point can still be maintained under such conditions, and why the bottom temperature doesn’t need to be considered at this time😂😂. Please give me some guidance; thank you!
Generally speaking, changes in the density of the components at the bottom of the tower are directly reflected in temperature changes. The components are light, and the bottom temperature is low. But in the case of increasing the amount of stripping steam (with the steam temperature being 40 to 50 degrees higher than the bottom temperature), the bottom temperature of the tower decreases. I’m not sure why the flash point can still be maintained under such conditions, and why the bottom temperature doesn’t need to be considered at this time😂😂. Please give me some guidance; thank you!
Generally speaking, changes in the density of the components at the bottom of the tower are directly reflected in temperature changes. The components are light, and the bottom temperature is low. But in the case of increasing the amount of stripping steam (with the steam temperature being 40 to 50 degrees higher than the bottom temperature), the bottom temperature of the tower decreases. I’m not sure why the flash point can still be maintained under such conditions, and why the bottom temperature doesn’t need to be considered at this time😂😂. Please give me some guidance; thank you!
Original poster, the process from low pressure to the fractionation tower is one of pressure reduction, and flashing occurs during this pressure reduction process; most instances of flashing involve a self-regulating temperature drop, so the temperature at the bottom of the tower is slightly lower than the feed temperature. Gas injection acts as a heat source for the distillation column, but the impact of gas injection on the bottom temperature must be considered within the overall thermal balance of the column; it is quite complex, and it cannot be simply said that an increased amount of gas injection will lead to a rise in the bottom temperature. One thing is certain: after inflation, the partial pressure of the oil and gas in the distillation tower decreases. There is a relationship between boiling point and pressure; therefore, when the pressure of a substance decreases, its boiling point also decreases. At the same temperature, more volatile light components are released, so the product at the bottom of the tower becomes heavier and its flash point rises. At the same time, as the amount of volatile light components increases, that is, as more substance changes from a liquid state to a gas state, the latent heat absorbed during vaporization increases according to the principles of phase change; as a result, the temperature at the bottom of the tower decreases. In the end, that situation you mentioned occurs: the inflation increases, the flash point at the bottom of the tower is high, and the temperature at the bottom of the tower is low. Hope this helps you
I understand a bit better, thank you! :D:D
In front of our distillation tower, there is a stripping tower: lol