Study on the performance of SiC sulfuric acid decomposer for hydrogen production in thermochemical cycle of high temperature gas-cooled reactor

[Background]: The thermochemical iodine sulfur(IS) and hybrid sulfur(HyS) cycles are considered as the most promising technologies for large-scale hydrogen production using the process heat from high temperature gas-cooled reactors(HTGRs). As the key component for coupling HTGR to the IS or HyS hydrogen production plant, the performance of the sulfuric acid decomposer (SAD) significantly impacts the coupling safety as well as the hydrogen production efficiency. [Purpose]: This study aims to develop a novel bayonet-type SiC reactor and investigate its heat transfer performance and sulfuric acid decomposition reaction performance. [Methods]: First of all, a novel bayonet-type SiC reactor was developed. Then, the heat calculation models for the sulfuric acid decomposition reaction and the SiC reactor were built using Aspen Plus. Subsequently, the reactor was subjected to a water inlet experiment, during which the inlet and outlet fluid temperatures, tube wall temperature, and pressure drop were tested. Moreover, the thermal load of the reactor was calculated, and the state changes of the inlet water inside the reactor were analyzed. Finally, the reactor was subjected to a sulfuric acid decomposition experiment to test the inlet and outlet fluid temperatures, tube wall temperature, pressure drop, and oxygen production rate. In addition, the thermal load of the sulfuric acid decomposition process was calculated. The heat transfer performance and reaction performance of the reactor were comprehensively evaluated based on the experimental results. [Results]: The results demonstrated that the SiC reactor with the new structure can reduce the assembly difficulties, increase the reaction flux, and achieve an oxygen production rate of up to 154 L·h-1. Compared with the original reactor, the reaction flux increases by 50%. In addition, the SiC reactor can enhance heat recovery and utilization; about 30% of the heat in the fluid heating process in the SiC reactor comes from the reaction products. [Conclusions]: This study provides a foundation for the development of a shell-and-tube type prototype SAD which may directly utilize heat from HTGR.