Fractionating tower problem
Thread Content
I have a question: during the separation of diesel and gasoline, if the composition ratio of the feed remains unchanged (for example, 90 tons of diesel and 30 tons of gasoline), and the pressure at the top of the tower stays constant (0.23 Mpa), what happens? To maintain the same diesel flash point, how should the bottom temperature of the tower be adjusted? (This temperature is measured at the product extraction line at the very bottom of the tower, after passing through the bottom heater.) Under what conditions should the temperature be increased, and under what conditions should it be decreased?
Increase the bottom temperature when the flash point is high, and decrease it when the flash point is low.
The question is, how should adjustments be made before the flash point is determined
The above are the reaction and distillation flowcharts
You’ve misunderstood; during normal daily production, sampling is carried out only at specific times. Therefore, it’s necessary to adjust the flash point before those times, while sampling can be done during production hours!
Oh, then it will have to be determined through trial and error, by comparing multiple sets of data to find the temperature range at which the flash point is appropriate
The temperature at the bottom of the tower is generally maintained at a certain level; if the flash point is too high, it is adjusted by modifying the draw rate and reflux rate.
Our flash point mainly adjusts the temperature of the medium taken from the bottom of the tower, while reflux mainly controls the dry point value.
Adjust according to the principle of a high bottom of tower temperature and a high flash point, and then determine the relationship between the flash point and the bottom of tower temperature for such raw materials in your facility, so as to guide your operations! For example, if you increase the temperature at the bottom of the tower by 2 degrees, the flash point will increase by 4-5 degrees, and that’s the kind of relationship
Generally, reflux is used to adjust the dry point and flash point of the gasoline at the top of the tower; more light components result in a lower flash point, which is a good way to understand it. If all other conditions remain unchanged, slightly increasing the top temperature will raise the flash point, while the bottom temperature generally does not need to be adjusted.