(656b) Building Block-Based Work and Heat Exchanger Network Synthesis (WHENS)
To this end, we provide a new representation approach to capture many process configurations of WHENS with innovative pathways . The new representation approach centers around two fundamental elements of abstract building blocks. Firstly, the block interior is used to represent splitting, mixing, utility cooling and utility heating of individual streams. Secondly, the block boundaries between adjacent blocks allow energy flow in the form of heat and work. An unrestricted boundary does not allow pressure and composition changes between adjacent blocks. A semi-restricted boundary is assigned with expansion/compression operations connected through either common (integrated) or dedicated (utility) shafts. A completely restricted boundary allows heat flow driven by temperature gradient across the boundary. We demonstrate the rich process information embedded in the proposed representation through literature examples. The novelty of this approach is that there is no need to specify the stage number as requested by the classic approach. Besides, the proposed representation approach allows automatic generation of numerous work and heat exchanger network with intensification opportunities. We formulate this building-block based WHENS as a mixed-integer nonlinear optimization (MINLP) problem with the objective as minimizing total annual cost. We use several literature examples on liquified energy chain to demonstrate the capability of the proposed synthesis approach.
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