Process modeling of a hybrid-sulfur thermochemical cycle combined with solid oxide fuel cell/gas turbine system

Abstract

This work proposes a novel design of the hybrid sulfur (HyS) thermochemical water-splitting cycle for hydrogen production. The hydrogen production plant is combined with a solid oxide fuel cell/gas turbine (SOFC/GT) system to satisfy the demand for the high-temperature heat from the HyS cycle by exploiting the heat loss of the SOFC stack and the demand for electric power for SO2-depolarized electrolysis. A detailed thermodynamic analysis of the HyS cycle and the SOFC/GT system was conducted on a flowsheet basis to determine the energy requirement and to estimate the effects of the operating conditions on the overall efficiency. As a result, it was found that the LHV efficiency of the combined HyS-SOFC/GT system can reach > 29% (34.32% HHV efficiency), with a net electric efficiency of the SOFC/GT system of 38.83% and consumption of 340.3 kJ molH2-1 high-temperature heat, 148.77 kJ molH2-1 low-temperature heat, and 134.35 kJ molH2-1 electric power.