CO₂ dispersion benchmarking against natural gas dispersion

Abstract

This paper aims to enhance the understanding of professionals involved in the development, engineering, operation and regulation of gas processing systems, particularly with respect to carbon capture and storage (CCS), regarding gas dispersion analysis. Traditionally, knowledge in this area is derived from experience in natural gas projects and simplified simulation analyses. This study investigates gas dispersion behaviour in the presence of obstructions during accidental methane and CO₂ releases using computational fluid dynamics (CFD) simulations with FLACS (FLame ACceleration Software). By modelling obstructed dispersion scenarios for both gases, the assessment examines the influence of operating conditions, facility layout and environmental factors. The study highlights similarities and differences in CO₂ and methane cloud development, offering insights into their dispersion characteristics. FLACS CFD modelling provides a detailed representation of transient and steady-state cloud behaviour, including obstruction effects, compared to free-field dispersion models like ‘EFFECTS’ or ‘Phast’, which, while faster and more user-friendly, offer a more simplified analysis. This comparison underscores the advantages of high-fidelity CFD simulations in complex gas dispersion scenarios. The results indicate that simplified methodologies may fail to fully capture cloud extent and, in some cases, underestimate associated risks.