ABSTRACT
This chapter uses case studies to illustrate the analysis portion of the Economic Design Model. The case studies show how one sets up and performs an analysis. This involves selecting the independent and dependent variables, estimating the differences in capital and production costs, calculating the NPVs of the options, and selecting the most economic option. The studies are:
• Finding the optimal cooling water outlet temperature in a heat exchanger cooling a hot stream
• Finding the optimal catalyst usage in a reactor/filter system • Finding the optimal amount of heat recovery in a heat exchanger loop • Determining whether to build a grass-roots plant or whether to expand an
existing plant • Finding the economically optimal number of plants
Most every process includes cooling a hot stream with cooling water. The engineer designing the process must select an outlet temperature for the cooling water. Deciding this involves looking at the cost trade-offs. For example, one could pick a higher outlet temperature and reduce cooling water usage and cost but that would increase the size and cost of the heat exchanger.
