Heat integration superstructures

HEAT-INTEGRATED DISTILLATION SEQUENCES BASED ON THE OPTIMIZATION OF A SUPERSTRUCTURE... 

The mathematical model is based on the superstructure shown in Fig. 11.2. The heat transfer fluid in heat storage remains in the storage vessel during heat transfer with only the process fluid pumped around. The superstructure also shows that each unit is capable of receiving external heating or cooling in addition to direct and indirect heat integration. 

In postulating a superstructure of alternatives for the heat-integrated distillation sequencing problem, we simultaneously embed ... 

The heat integration alternatives consist of only the different matches that may take place and do not include structural alternatives of the heat exchanger network topology presented in the hyperstructure or superstructure sections of HEN synthesis. 

To determine a least total annual cost heat-integrated sequence of distillation columns from the postulated superstructure, we define variables for... 

The systematic development of superstructures for heterogeneous systems is, in principle, a more difficult task. Consider, for instance a process flowsheet that is composed of reaction, separation, and heat integration subsystems. In theory, one could develop a superstructure by combining the superstructures for each subsystem. However, this approach could lead to a very large MINLP optimization problem. 

This paper describes an integrated MINLP synthesis of overall process schemes using a combined synthesis / analysis approach. The synthesis is carried out by a multilevel-hierarchical MINLP optimization of the flexible superstructure, whilst the analysis is performed in an economic attainable region (EAR). The role of the MINLP synthesis step is to obtain a feasible and optimal process structure, and the role of the subsequent EAR analysis step is to verify the MINLP solution and to propose in the feedback loop, any profitable superstructure modifications for the next MINLP. The main objective of the integrated synthesis is to exploit interactions between the reactor network, separator network and the remaining part of the heat/energy integrated process scheme. 

The MINLP model is bas on the superstructure (Fig. 1). Hot and the cold process streams of the existing nonretrofitted processes (Kovac Kralj et al., 2002) solvent recovery (E204), the refinery (FG, E211, E210, S80), the formalin (ElO, E5, E6) and the methanol (ACl) or retrofitted methanol (SG) or retrofitted refinery (RS80) which are heated or cooled by utility, are included in the superstructure. The superstructure is including the integration between ... 

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