Vacuum distillation problem

A small pressure drop indicates a low amount of material; with no change in backflow, the top of the tower remains pure.

As the vacuum level decreases, the evaporation rate drops under the same conditions; simultaneously, the amount of heavy components also decreases. Therefore, it is normal for the purity of the product to increase. However, you will also notice that the boiling temperature rises, and the level in the reflux tank increases slowly.

1. Under reduced pressure, the relative volatility of a substance system decreases； 2. Under reduced pressure, the volume of the gas increases, resulting in a decrease in the processing capacity per unit of tower ； 3. Under reduced pressure, the bubble point of a substance decreases, making it easier to carry out production using low-pressure steam ； 4. Reduce thermal decomposition under reduced pressure. So, your vacuum level decreases and the pressure at the top of the tower rises: this indicates an increase in the volume of the light components. This can be attributed to an increased relative volatility, which leads to an accumulation of those light components, or it could also be due to a reduction in the cooling effect from the reflux at the top of the tower. I think the temperature at the top of your tower must have increased as well. The pressure drop in the tower has decreased: this indicates that the physical properties of each layer are now more similar to those of previous layers, which means that the separation efficiency of the tower has declined; as a result, your steam consumption must have increased significantly. Increased purity of the overhead product: This indicates that the concentration of the components in the overhead is higher than before, which is also due to an increase in relative volatility.

That’s right, the temperature at the top of the tower has increased; the other conditions are as mentioned above