Design of Catalytic Recombiners for Safe Removal of Hydrogen From Flammable Gas Mixtures-Paper

Several today?s and future applications in energy technology bear the risk of the formation offlammable hydrogen/air mixtures either due to the direct use of hydrogen or due to hydrogenappearing as a by-product. If there?s the possibility of hydrogen being released accidentally into closedareas countermeasures have to be implemented in order to mitigate the threat of an explosion. In thefield of nuclear safety passive auto-catalytic recombiners (PAR) are well-known devices for reducingthe risk of a hydrogen detonation in a nuclear power plant in the course of a severe accident. Hydrogenand oxygen react on catalyst materials like platinum or palladium already far below conventionalflammability limits. The most important concern with regard to the utilization of hydrogenrecombiners is the adequate removal of the reaction heat. Already low hydrogen concentrations mayincrease the system temperature beyond the self-ignition limit of hydrogen/air mixtures and may leadto an unintended ignition on hot parts of the PAR.Starting from the nuclear application, since several years IEF-6 and LRST perform joint research inthe field of passive auto-catalytic recombiners including experimental studies, modeling anddevelopment of new design concepts. Recently, approaches on specifically designed catalysts and onpassive cooling devices have been successfully tested. In a design study both approaches are combinedin order to provide means for efficient and safe removal of hydrogen. The paper summarizes resultsachieved so far and possible designs for future applications.