Two-component distillation column top: The composition of the material at the column top is determined based on the top pressure and top temperature
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In two-component distillation, given the temperature and pressure at the top of the tower and the fact that there are only two components, A/B, how can one determine the composition of the material at those temperature and pressure levels (i.e., the percentages)?
It is a typical phase equilibrium calculation; however, due to the high precision required in controlling component concentrations, temperature changes cannot be used as a reference variable. In practice, the temperature difference across several plates or the concentration gradient at the top of the tower is used as the target variable to indicate the purity at the tower top
According to Dalton’s law of partial pressures, it is necessary to know the saturated vapor pressures of A and B at this temperature; by then using the actual pressure along with Dalton’s law of partial pressures, it is possible to calculate the composition in both the gas phase and the liquid phase
Reply to 3# ai444099439: Thank you. I’ll go to work tomorrow and take a look at it
Great post, let’s learn from it haha
It can only be an approximate ratio; it won’t be very specific. The decision is mainly based on practical experience
This is a typical bubble point-T calculation: by selecting the appropriate thermodynamic equation and using the phase equilibrium relations, the calculation can be carried out.