New Synthesis Procedure To Find the Optimal Distillation Sequence with Internal and External Heat Integrations

Recent developments in energy conservation have sought internal heat integration through side heat exchangers as an attractive energy-efficient alternative to reduce the energy consumption in conventional distillation. However, it is difficult to estimate the effect on the reduction of reboiler duty through internal heat integration without executing rigorous simulations. Thus, the stages used for heat exchange have been selected by trial and error or some heuristics. For a fixed design where heat integration between a rectifying section and a stripping section takes place, current research has derived the optimal structure by trial-and-error or systematic approaches. In this work, the combination of superstructure representation, rigorous simulations, and mathematical programming is effectively used to develop a systematic synthesis procedure, which can derive the optimal distillation process structure including the internal and external heat integration. In the proposed procedure, piece-wise linear functions between the amount of internal heat exchange and the reduction of reboiler and condenser heat duties are derived in advance by executing rigorous simulations. Then, for every pair of rectifying and stripping sections of two columns, the optimal structure with internal heat integration is derived by solving an MILP problem. The cost of side heat exchangers, and the condenser and reboiler duties and areas resulted from internal heat integration are used as parameters in the formulation of a synthesis problem which comprises all the possible distillation sequences. By adopting such a procedure, the overall synthesis problem can also be formulated as an MILP problem, and the optimal process structure can be derived by solving it. The result of a case study to separate a ternary mixture shows the effectiveness of the proposed synthesis method.

[1]  Mark J. Andrecovich,et al.  An MILP formulation for heat‐integrated distillation sequence synthesis , 1985 .

[2]  C. Floudas,et al.  A mixed-integer nonlinear programming formulation for the synthesis of heat-integrated distillation sequences , 1988 .

[3]  Kejin Huang,et al.  A Simplified Scheme of Externally Heat-Integrated Double Distillation Columns (EHIDDiC) with Three External Heat Exchangers , 2010 .

[4]  Eric S. Fraga,et al.  Evaluation of hybrid optimization methods for the optimal design of heat integrated distillation sequences , 2003 .

[5]  Young Han Kim.  Internally and Partially Heat-Integrated Distillation System for Ternary Separation , 2011 .

[6]  Bodo Linnhoff,et al.  Distillation column targets , 1993 .

[7]  Akira Endo,et al.  Performance of an Internally Heat-Integrated Distillation Column (HIDiC) in Separation of Ternary Mixtures , 2006 .

[8]  Mamdouh A. Gadalla.  Internal heat integrated distillation columns (iHIDiCs)—New systematic design methodology , 2009 .

[9]  Shaofeng Wang,et al.  Comparing three configurations of the externally heat-integrated double distillation columns (EHIDDiCs) , 2011, Comput. Chem. Eng..

[10]  Qunxiong Zhu,et al.  Design and control of an ideal heat-integrated distillation column (ideal HIDIC) system separating a close-boiling ternary mixture , 2007 .

[11]  Masaru Nakaiwa,et al.  Internally Heat-Integrated Distillation Columns: A Review , 2003 .

[12]  Amiya K. Jana,et al.  A novel intensified heat integration in multicomponent distillation , 2012 .

[13]  J. Segovia-Hernández,et al.  Assessment of the Implementation of Heat-Integrated Distillation Columns for the Separation of Ternary Mixtures , 2011 .

[14]  伸治 長谷部,et al.  内部熱交換型蒸留塔（HIDiC）における内部熱交換量分布の省エネルギー性能に与える影響 , 2011 .

[15]  J. de Graauw,et al.  Internal heat integration – the key to an energy‐conserving distillation column , 2003 .

[16]  Richard S.H. Mah,et al.  Distillation with secondary reflux and vaporization: A comparative evaluation , 1977 .

[17]  Kejin Huang,et al.  Externally Heat-Integrated Double Distillation Column (EHIDDiC): Basic Concept and General Characteristics , 2010 .

[18]  Keigo Matsuda,et al.  Energy Saving Characteristics of the Internally Heat Integrated Distillation Column (HIDiC) Pilot Plant for Multicomponent Petroleum Distillation , 2008 .

[19]  Mamdouh A. Gadalla,et al.  Pinch Analysis-Based Approach to Conceptual Design of Internally Heat-Integrated Distillation Columns , 2005 .

[20]  Wolfgang Marquardt,et al.  Heat‐integrated distillation columns: Vapor recompression or internal heat integration? , 2012 .