Process Safety Considerations in the Design and Scale-Up of Chemical Looping Processes

The technology readiness of chemical looping is rapidly being advanced by transforming batch-mode bench-scale systems into continuously or semicontinuously operating pilot units, and these changes in operating modes and scales introduce new levels of risk. To ensure pilot plants operate in a safe and successful manner and to sustain public support and a positive perception, it is important that a rigorous process safety approach is implemented in both the design and the operations stages of facilities, especially with limited operating history at larger scales. Beyond the application of technically sound engineering of individual unit operations, additional considerations are required for safer operations. The application of the inherently safer design (ISD) principles of minimization, substitution, moderation, and simplification are discussed within the context of chemical looping facilities, and example-based guidance is provided. Particular attention is paid to the selection of oxygen carriers and materials of construction to reduce or eliminate hazards. Passive and active control strategies are briefly discussed for their potential to mitigate accidents in pilot facilities, principally in managing loss of containment through secondary containment, and protecting workers through flame arresting and shielding. Management of change is introduced in a chemical looping pilot plant context, focused on examining alternative configurations and materials, recommissioning plants, and managing documentation and training with high turnover in academic settings. Finally, the need for incident reporting and knowledge sharing related to safety and accidents in the chemical looping community are discussed and recommendations on how this can be implemented are made.