Process Integration: HEN Synthesis, Exergy Opportunities

This chapter provides a brief description of thermodynamic analysis, the maximization of heat-recovery and power generation and the synthesis of IGCC’s heat exchanger network. Trade-offs between the income from power generation and utility costs plus the investment in HEN are studied with respect to the generation of different pressure-levels of steam and temperature driving force losses within the heat-recovery network. A combined pinch analysis/mathematical programming approach is applied and the optimization models are described for (i) the maximization of heat-recovery and power generation, and (ii) a synthesis of the heat-recovery and steam/power generation network. A sensitivity analysis for the synthesis is performed in order to show how optima are sensible for the expected increase in future electricity and utility prices, and the project’s lifetime. The results obtained from the studied IGCC process indicate that detailed optimization has to be performed during the network synthesis step, otherwise optimal trade-offs are missed that may result either in serious power generation losses or in obtained over-designed networks.