Numerical Study on the Operational Behavior of Catalytic Components With Spherical Packed Bed Structures

Abstract In order to mitigate the potential risk of hydrogen explosion in severe accidents, Passive Autocatalytic Recombiners (PARs) have become widely employed in the containment atmosphere of PWR nuclear power plants in recent years. Catalytic components with spherical packing forms, characterized by a larger catalytic specific surface area, show significant potential to enhance the hydrogen removal capability of PARs. Three typical structured packing forms are considered: simple cubic (SC), body center cubic (BCC) and face center cubic (FCC) arrangements of packed catalyst spheres. The numerical models of catalytic components were constructed using the CFD software STAR-CCM+. The elementary reaction mechanism is employed as the reaction kinetics model to describe the reaction process. When the inlet hydrogen concentration is 4.0 vol.% and the inlet velocity is 0.3 m/s, the results indicate that hydrogen removal efficiencies for the SC, BCC, and FCC arrangements of packed catalyst spheres are 81.47%, 98.89%, and 99.87%, respectively. Notably, the FCC catalytic component exhibits the highest hydrogen removal capability. However, the most complex structure and densest arrangement of the FCC catalytic component also introduce the highest flow resistance coefficient, reaching 43.04.