Retrofit design of processes

Retrofit design precludes the decomposition usually adopted in grassroots design where process decisions are made first to be followed by equipment decisions. The lack of this decomposition forces a potentially explosive growth in the search space. Retrofit design also requires models that can rate existing equipment for proper analysis; these models are much more complex. This paper reviews the as yet sparsely populated process retrofit literature where most work is for redesigning heat recovery systems. We see evolutionary strategies that reflect ones inability to explore all alternatives. It concludes with an assessment of where we are and ideas for future developments.