Applications of genetic optimization and case-based reasoning for synthesis of inherently safer chemical processes

In the paper an approach for synthesis of inherently safer chemical processes is presented. Process synthesis is a task of formulating process configuration for a purpose by defining the operations used and how they are connected. Inherent safety is a principle which strives to enhances the safety by using the safe properties of the system such as safer equipment and operating conditions. Process synthesis can be considered as an optimization task. Because the model is uncontinuous, ordinary optimization methods cannot be used, but a genetic algorithm is employed instead. In a genetic algorithm the structure of the process is represented as a string of integers, which describes the operations required and how they are connected together. An inherent safety index is used as an objective function in the genetic algorithm (i.e. fitness). The index has been developed for safety estimations in the early stages of process design. Most of the subindices of the method are quite simple to, estimate, except the subindex for safe process structure, which is estimated by case-based reasoning by using a database of good and, bad design cases. The database is collected from existing design cases, design recommendations and accident reports. By this method the experience from earlier designs can be reused and, the same design mistakes are not done again. Finally two process design case studies have been given.