Heat exchanger network target

Heat Exchanger Network and Utilities Energy Targets... 

The analysis of the heat exchanger network first identifies sources of heat (termed hot streams) and sinks (termed cold streams) from the material and energy balance. Consider first a very simple problem with just one hot stream (heat source) and one cold stream (heat sink). The initial temperature (termed supply temperature), final temperature (termed target temperature), and enthalpy change of both streams are given in Table 6.1. 

After maximizing heat recovery in the heat exchanger network, those heating duties and cooling duties not serviced by heat recovery must be provided by external utilities. The outer-most layer of the onion model is now being addressed, but still dealing with targets. 

The energy cost of the process can be set without having to design the heat exchanger network and utility system. These energy targets cam be calculated directly from the material and energy balance. Thus... 

Figure 7.9 The Xp parameter avoids steep slopes on the Fp curves, whereas minimum Fp does not. (Reprinted from Ahmad, Linnhoff, and Smith, Cost Optimum Heat Exchanger Networks II. Targets and Design for Detailed Capital Cost Models, Computers Chem, Engg., 7 751, 1990 with permission from Elsevier Science, Ltd.)...

Calculate the capital cost target for the mixed specification heat exchanger network from Eq. (7.21) using the cost law coefficients for the reference specification. 

Once a design is known for the first two layers of the onion (i.e., reactors and separators only), the overall total cost of this design for all four layers of the onion (i.e., reactors, separators, heat exchanger network, and utilities) is simply the total cost of all reactors and separators (evaluated explicitly) plus the total cost target for heat exchanger network and utilities. 

Townsend, D. W., and Linnhoff, B., Surface Area Targets for Heat Exchanger Networks, IChemE Annual Research Meeting, Bath, U.K., 1984. 

Saboo, A. K., Morari, M., and Colberg, R. D., RESHEX An Interactive Software Package for the Synthesis and Analysis of Resilient Heat Exchanger Networks II. Discussion of Area Targeting and Network Synthesis Algorithms, Computers Chem. Eng., 10 591, 1986. 

Ahmad, S., and Smith, R., Targets and Design for Minimum Number of Shells in Heat Exchanger Networks, IChemE, ChERD, 67 481, 1989. 

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