Page 190 - Distillation theory

P1: JPJ/FFX P2: FCH/FFX QC: FCH/FFX T1: FCH
0521820928c05 CB644-Petlyuk-v1 June 11, 2004 20:15

164 Distillation Trajectories and Conditions of Mixture Separability

D

Q
con

Q inter Figure 5.36. The column with the heat output (Q inter ) in the feed
F
cross-section.

Q
reb

B

reversible distillation trajectories from product points. If these bundles intersect
each other, the separation is feasible. Otherwise, it is not feasible.

5.8. Conclusion

At sharp distillation with finite reflux, the product points should belong to possible
j j
product regions Reg and Reg at those boundary elements of concentration
D B
i i j j
t
t
simplex at which trajectory tear-off regions Reg and Reg are available. In the
r s
i i
tear-off points equilibrium coefficients of absent components j should be smaller
(bigger) than those of present components i in the top (bottom) section (K ri > K rj ,
K si < K sj ). Section trajectories tear off from the boundary elements at the value
of the parameter L/V greater than the values of phase equilibrium coefficients of
t
the absent components (L/V > K j ) in tear-off point x .
In the mode of minimum reflux, R min at sharp distillation without distributed
components trajectory of the top (bottom) section goes from the product point x D
1
1
(x B ) to the trajectory tear-off point S (S ) into the boundary element, containing
r s
one additional component referring to product components, that is the closest
1
1
one by phase equilibrium coefficient, then it goes from point S (S ) to the point
r s
2
2
of trajectory tear-off S (S ) inside concentration simplex, then it goes from point
r s
2
2
S (S ) to point x f −1 (x f ) in the feed cross-section of the column. Along with that,
r s
material balance should be valid in the feed cross-section.
1
2
Separatrix sharp region of the section trajectories Reg sh,R ≡ S − S − N +
sep
passing through product point has the dimensionality equal to the difference be-
tween the number of components in feeding and the number of components in the