A sudden increase in the reflux ratio causes imbalance in the distillation column
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I seek advice from experts. In the propylene distillation tower, a drift in the value of a sensor in the automatic control system caused the reflux rate to increase suddenly by almost a factor of two. The reflux temperature is 50°C, with the top of the tower maintained at 56.1°C ± 0.5. When the reflux is increased, the temperature in the stripping section drops rapidly, while the temperature in the distillation section rises. How can this phenomenon be explained theoretically? Can it be understood that overly large and excessively cold reflux liquid causes all of the rising vapor phase to be condensed?
I agree with the opinion from the second floor; it is likely that an excessive reflux ratio disrupts the gas-liquid exchange equilibrium in the distillation section. This is equivalent to reducing the number of tray levels, which in turn leads to a decrease in the pressure drop across the top and bottom of the tower. As the pressure drop at the bottom of the tower decreases, the evaporation temperature also drops. Due to the reduced number of trays in the distillation section, the gas rises too quickly, resulting in an increase in the temperature at the top of the tower
Yes, I’ve considered that as well, but it seems that the tower pressure decreases when flooding occurs (I’m not sure if I understand this correctly). The operating pressure for this tower is 0.21 bar, while during the occurrence of problems, the tower pressure remains around 0.35 bar.
Thanks for the advice. I have time to upload all the pictures. When that happens, the tower pressure increases. It increased from 0.21 liters to 0.35 bar. I don’t know where I misunderstood.
After a sudden increase in the reflux ratio, it is as if the height of the tower has been reduced; consequently, the actual position of the tower top changes. As mentioned on the second floor, liquid flooding at the top causes the pressure at what appears to be the tower top to not reflect the actual pressure at that point – it is merely the physical top of the tower