Assume total reflux condition at steady state. This condition means zero product flow at top, ok?
Now make a mass balance in the column: bottom flow equals feed.
In other words there is a pure product at the top, with zero flow. There are energy input at the bottom and energy removal at the top, but there is no separation. The condition of total reflux is used in batch operation tho improve separation at the best distillate we can take. This means: make a total reflux for sometime. make zero reflux and take the "best" top product for another small time and then repeat the operation.
According to the mass conservation law, it is impossible. Total reflux for continuous operation can be accepted during the starting up.
Under total reflux condition, column can only be operated in batch mode without any external feed flow and the assumption of constant molar overflow on a tray is obeyed. Theoretically, this condition yields the maximum separation efficiency of the column where both the operating lines fall on the 45 deg diagonal line (x=y) resulting in minimum number of trays in the well known McCabe Thiele diagram.
The concentration of the liquid and vapor on each tray, the reflux condenser and the reboiler is constant. I could tell you the reasons if you wish to know.
For continous distilation Total reflux condition can also termed as no feed condition. At thr initial startup for Distilation column to acheive stabilization for stage wise concentrations i.e., for enriching high volatile increasing towards top tray. Once the maximum separation attained and there is no further mass transfer taking place between any considered stages can be termed as Steady state. At these conditions, there is changes in molar enthalpies of all stages from reboiler to condensers.
How about if use the regular batch reactive column (CBD) for this reaction scheme:
A (413.5 K) + B (390.9 K) C (420.8 K) (main product) + D (337.15 K)
Do I need to assume the compositions of condenser and all trays the same composition as the fresh feed charged to the reboiler at the beginning of process and then operate the CBD column under total reflux ratio for some time until it reaches the steady-state condition to establish the column composition profiles or already assumed that the mixture in the reboiler, in the plates and in the condenser are at the boiling point at time t = 0 (beginning of the process). There is no pre-assigned period of total reflux operation since the desired product (C) has low relative volatility?
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