Vapor-liquid equilibrium in distillation columns

This issue cannot be clarified in one or two sentences; adjustments need to be made based on the actual situation.

Changes in the feed composition have a direct impact on distillation operations; as the concentration of heavier components in the feed increases, the load on the distillation section rises. For a tower with a fixed number of rectification section plates, this will result in the heavier components being carried to the top of the tower, causing the quality of the product at the top to be substandard. If the concentration of the light components in the feed increases, the load on the stripping section increases. For a column with a fixed number of plates in the stripping section, this will result in incomplete evaporation of the light components in that section, leading to an increased loss of light components in the bottom liquid. At the same time, changes in the feed composition will also cause changes in the material balance of the entire tower and the process conditions. As the composition becomes lighter, the overhead distillate increases while the amount of liquid discharged from the reactor decreases. At the same time, the temperature of the entire tower decreases while the tower pressure increases. The component becomes heavier; the situation is the opposite. When the feed composition changes, the following measures can be taken. (1) Improve the feed port. When the component becomes heavier, adjust the feed inlet downward ； When the component becomes lighter, move the feed inlet upward. (2) Change the reflux ratio. Increase the reflux ratio when the component weight increases ； When the component becomes lighter, reduce the reflux ratio. (3) Adjust the refrigerant and heat dosage. Based on changes in the composition, the amount of refrigerant at the top of the tower and the heat input at the bottom of the tower are adjusted accordingly to maintain constant product quality at both the top and the bottom.