Increase the operating pressure of the tower

It is generally in line with this principle: the higher the pressure, the lower the latent heat, and thus the smaller the heat source required at the bottom of the tower. However, (1) as the temperature of the heat source at the bottom of the tower increases, and (2) at high pressures the relative volatility decreases which leads to an increased reflux ratio. Therefore, in practice, it seems that the lower the pressure, the less heat source is needed

Reply to 2# fang_yanchen: If pressure increases and latent heat decreases, doesn’t that mean the boiling point should decrease as well? That doesn’t match reality, right?

I’m not sure what the other condition set in your setup is – the reflux ratio or the flow rate. If that’s the case, then there’s no problem with this result. The analysis is as follows: as pressure increases, the boiling point rises, less material vaporizes, and the flow rate at the top of the tower decreases; thus, the load on the tower can be reduced. It is recommended that you try fixing the outlet flow at the top of the tower; in that case, the load at the bottom of the tower should increase as the pressure rises. . Looking forward to your results. . .

In my setup, I used two parameters: the outflow rate and the reflux ratio. When the operating pressure of the tower is increased, the heat load at the top of the tower decreases, while the heat load at the bottom of the tower increases. As analyzed above, as the column pressure increases, the boiling point rises, resulting in less material vaporizing. However, to maintain a certain flow rate, the heat load at the bottom of the column must increase in order to boost the amount of material that vaporizes. Actual verification shows the same thing, but the separation efficiency changes very little with operating pressure – how can this be explained?

Does LZ’s first post say that the tower bottom load decreases as pressure increases? ? When I say the vaporization volume decreases, I mean that since there is no fixed top distillate volume, it is possible for the load on the bottom of the tower to decrease. . If the setup specifies both the outflow rate and the reflux ratio, it is reasonable for \"an increase in the operating pressure of the tower to result in a decrease in the heat load at the top of the tower and an increase in the heat load at the bottom of the tower.\" The heat load at the bottom of the tower increases because as pressure rises, the boiling point also rises, requiring more sensible heat to be supplied, thus increasing the load ； The top of the tower should experience bubble point reflux; the composition at the top of the tower doesn’t change much. The bubble point increases as pressure rises, and the Δt for condensation may decrease, which could result in a reduced load on the condenser. . . The separation efficiency is mainly related to the theoretical plate number and the reflux ratio, while the influence of pressure is relatively minor. . .