Fluctuations in diesel upgrading distillation column

It should be with water; what is the steam temperature in your stripping tower? ? It is caused by water being carried into the distillation tower by the stripping steam!

We have encountered this situation in the gasoline hydrogenation unit of our facility; it is similar to the situation you mentioned above. If this persists, the fluctuations in tower top pressure will also increase. Our corrective measures are as follows: 1. Switch the level control of the reflux tank to manual control, setting the value lower than normal. 2. Put both the bottom liquid level and the reflux flow under manual control; the tower top pressure can also be adjusted manually depending on the circumstances. Generally, the fluctuations in tower top pressure are not significant in the initial stage. Raising the temperature at the bottom of the tower helps to evaporate the water inside it, and usually, operations return to normal after about half an hour. The main reason for this phenomenon is that when water returns to the system, it forms an oil-water mixture with the oil; the boiling point of this oil-water mixture is lower than that of either oil or water alone. As a result, a large amount of light components are carried upward and vaporized, causing the temperature at the top of the tower to drop. However, due to the high latent heat of water, the temperature rises again after cooling.

It is likely caused by water in the reflux stream at the top of the distillation column. As mentioned above, the level of the reflux tank at the top of the distillation column should be controlled manually. The level of the reflux tank at the top of the stripping tower should also be checked; operators on site compare these levels and adjust the opening degree of the control valve accordingly. If the level is too high or the system malfunctions, the bypass line of the control valve should be activated promptly, or even an on-site vent should be used. 4 Mainly, it is to check how much the amount of condensate produced outside the boundary condition has fluctuated compared to before, in order to adjust the amount of steam used for stripping in the stripper. It is also necessary to check whether the high and low level cut-offs at the front are set too high or are not functioning properly, as water may be entering the distillation system. Raise the bottom temperature of the distillation column; it will be fine once this wave passes. If the product contains water, dehydration in the tank area will suffice; however, if sampling is done for testing, the results will not be good, and it is possible that the product will fail the tests.

Thank you all for your replies; I’ve learned a lot. . .