Process Synthesis

This chapter provides an introduction to Process Synthesis. Sections 7.1 and 7.2 discuss the components of a chemical process system and define the process synthesis problem. Section 7.3 presents the different approaches in the area of process synthesis. Section 7.4 focuses on the optimization approach and discusses modeling issues. Finally, Section 7.5 outlines application areas which are the subject of discussion in chapters 8, 9 and 10. Process Synthesis, an important research area within chemical process design, has triggered during the last three decades a significant amount of academic research work and industrial interest. Extensive reviews exist for the process synthesis area as well as for special classes of problems (e.g., separation systems, heat recovery systems) and for particular approaches (e.g., insights-based approach, optimization approach) applied to process synthesis problems. These are summarized in the following: Overall Process Synthesis: Hendry et al. (1973) Hlavacek(1978) Westerberg (1980) Stephanopoulos (1981) Nishida et al. (1981) Westerberg (1989) Gundersen(1991) Heat Exchanger Network Synthesis: Gundersen and Naess (1988) Separation System Synthesis: Westerberg (1985) Smith and Linnhoff( 1988) Optimization in Process Synthesis: Grossmann (1985), (1989), (1990) Floquet et al. (1988) Grossmann et al. (1987) Floudas and Grossmann (1994) Prior to providing the definition of the process synthesis problem we will describe first the overall process system and its important subsystems. This description can be addressed to the overall process system or individual subsystems and will be discussed in the subsequent sections. An overall process system can be represented as an integrated system that consists of three main interactive components : (i) Chemical plant, (ii) Heat recovery system, (iii) Utility system. In the chemical plant, the transformation of the feed streams (e.g., raw materials) into desired products and possible by-products takes place. In the heat recovery system, the hot and cold process streams of the chemical plant exchange heat so as to reduce the hot and cold utility requirements. In the utility plant, the required utilities (e.g., electricity and power to drive process units) are provided to the chemical plant while hot utilities (e.g., steam at different pressure levels) are provided to the heat recovery system.