Figure 5.19 Effect of reflux.
Figure 5.21 Effect of reflux on composition profiles.
Figures 5.20 and 5.21 present temperature and composition profiles for three value of reflux. Low reflux flowrates produce lower concentrations of light inert component I and higher concentrations of heavier components B and C in the column, so temperatures are higher. High reflux flowrates have the opposite effect, so temperatures are lower.
The chemical equilibrium constant in the base case is 50. Reducing the value of KEq makes it more difficult to achieve the desired high conversion. We would expect that vapor boilup would have to increase. The upper left graph in Figure 5.22 shows that this is indeed what happens.
In addition to increasing energy consumption, reducing KEq increases the loss of reac-tant. The upper right graph in Figure 5.22 shows that more A is fed, and the lower left graph shows that the impurities of both reactants increase in the distillate. Figures 5.23 and 5.24 provide the temperature and composition profiles, respectively, for three values of KEq. As the chemical equilibrium constant decreases, the concentrations of heavy component C on the trays in the column decrease and the concentrations of the light inert increase. The result is lower temperatures in the column.
The concentration of inert in the fresh feed of reactant A is assumed to be z0A(A) = 0.50 in all of the cases considered in the previous sections. Now we wish to see how this
Was this article helpful?