A process modularity approach for chemical process intensification and inherently safer design

Process intensification through hybrid equipment combining unit operations has the potential for reducing energy demand and improving the safety of a chemical process. Selecting which unit operations to combine into an intensified unit is necessary in developing an intensified process that offers an inherently safer design with reduced energy demand. This paper presents a novel methodology to intensify a chemical process guided by modularity. A process network is decomposed into modules by applying a community detection algorithm to find the process units to be integrated into an intensified "module" to improve the Fire and Explosion Damage Index (FEDI). A case study for the separation of an ethanol-butanol-water mixture illustrates this approach. The results show that the safest design (lowest FEDI) is Alternative 1 which was developed using the approach and correlates with high modularity of 0.607. Energy use is reduced by 25.8% thus also leading to a more energy efficient process compared to the non-intensified design with a lower modularity (0.385). A rather empirically guided design was proposed as Alternative 2 which led to modularity of 0.533, but only 10% energy saving and no improvement in the FEDI. This demonstrates that intensification guided by modularity strengthens integration between the process units while improving both safety and energy efficiency. As such, the approach has a wide potential application to guide the intensification of chemical processes.