The fact that a heat integrated distillation column (HIDiC) may have multiple steadystatesand unstable operating regions has been recently recognized. Practically andoperationally, the existence of an unstable operating region would not be preferable,because it may cause abrupt changes in operating conditions. This paper shows twokinds of possible approaches to avoiding the multiplicity of HIDiC. The first approachis related to compressor operation strategies in LV control structure. A detailedcomparison of three strategies shows that the strategy of constant compressor rotationspeed is beneficial to the stable operation without multiple steady-states. The secondapproach is to adopt the DV or LB control structure. With one of these twoconfigurations, there is no multiplicity in operating regions and stable operation ofHIDiC can be realized.
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