(408a) New Insights In Distillation Design Via Column Profile Maps: Sharp Splits

In recent years there has been a
renewed interest in the design of distillation processes. Holland et al. (2004
a, b) and Tapp et al. (2004) have recently introduced the use of Column Profile
Maps (CPMs) to gain insight into complex distillation systems, and have also
shown that separations that were previously thought infeasible are in fact
feasible at certain operating conditions. They have also shown that CPMs are a
simple topological transformation of Residue Curve Maps (RCMs).

CPMs are dependant on two main parameters:
RΔ (reflux)
and xΔ (a
pseudo composition vector). This paper focuses on the interaction between these
parameters for the special case of sharp splits. With the CPM technique it has
been shown that sharp splits behave uniquely to non-sharp splits, so much so
that by fixing the aforementioned parameters in a specific manner it may be
possible to sample the intermediate boiler in an ideal system (i.e. constant
relative volatilities) as a bottoms product. This is possible due to a ?node
bumping? phenomenon, which could allow for much more efficient designs in distillation.
The effect of crossing the discontinuity region for ideal thermodynamics in
CPMs has also been investigated. The discontinuity effectively changes the
nature of stationary points, which might also be used to design more effective
columns.

To summarize, this paper focuses
on the use of CPMs to design distillation columns for sharp splits. The
interesting behavior displayed by sharp splits can be of great use to the
design engineer, in that many new, more efficient columns can be built.

References:

Holland, S.T., Tapp, M.; Hildebrandt, D. and Glasser, D., Column
Profile Maps. 2. Singular Points and Phase Diagram Behavior in Ideal and
Nonideal Systems, Ind. Eng. Chem. Res.,43(14),
p3590-3603, (2004 b).

Holland,
S.T., Tapp, M.; Hildebrandt, D., Glasser, D. and Hausberger, B., Novel
Separation System Design Using ?Moving Triangles?, Comp. and Chem. Eng.,29,
p181-189, (2004 a).

Tapp,
M., Holland, S.T.; Hildebrandt, D., and Glasser, D., Column Profile Maps. 1.
Derivation and Interpretation, Ind. Eng. Chem. Res.,43(2), p364-374,
(2004).