Because of the complicated interplay between the prefractionator and main distillation column involved

the black-hole problem might occur and prohibit the assignment of four specifications to dividing-wall distillation columns (DWDCs) (

e.g

.

the three main product compositions plus an impurity ratio in the intermediate product)

which lowers terribly process flexibility and operability. In this paper

a feed thermal condition adjustment strategy

achieved by the installation of a pre-heater in feed pipeline

is employed to eliminate the black-hole problem and serve to enhance process flexibility and operability. Through the strong influence to the overall mass and energy balance of the DWDC

the feed thermal condition adjustment can alter the interlinking flows between the thermally coupled prefractionator and main distillation column and work effectively to coordinate their relationship. A DWDC separating a benzene

toluene

and

o

-xylene mixture is chosen to ascertain the feasibility of the philosophy proposed. The static and dynamic studies demonstrate that the feed thermal condition adjustment is an effective way to refine process design and can c

ompletely eliminate the black-hole problem and elevate consequently process flexibility and operability.