Assessment of carbon capture and utilization in steelmaking: A case study using a hybrid fuel cell - gas turbine system

This paper investigates a carbon capture and utilization plant that converts steelmaking exhaust gases into valuable fuels. It examines the behavior of synthesis gas, identifies optimal operational parameters, and explores kinetics for methanol and ethanol production. Additionally, it examines the impact of varying H₂/CO, and H₂/CO₂ ratios and evaluates the efficiency of a hybrid system combining a solid oxide fuel cell (SOFC) and gas turbine (GT) powered by synthesized methanol. Using the Chemical Equilibrium with Applications software, the study analyzes the dynamic behavior of synthesis gas molar fractions within the water-gas shift reactor and Fischer Tropsch reactor. Optimal operational parameters were identified at a temperature range of 200–250 °C, pressure of 4.5 MPa, H₂/CO, and H₂/CO₂ ratios of 2.0, enabling efficient carbon conversion. Further exploration into the kinetics, alongside the commercial Cu/ZnO/Al₂O₃ catalyst in the Fischer Tropsch synthesis, supports methanol and ethanol production. Increased H₂/CO, and H₂/CO₂ ratios favor methanol production with lower carbon dioxide fractions, while ethanol production and CO₂ emissions decrease as these ratios rise. Finally, a case study incorporates exergoeconomic and exergoenvironmental analyses of a SOFC-GT hybrid system fuelled by methanol from Fischer Tropsch synthesis, where the combustor exhibits the lowest exergy efficiency (62.3%), while the fuel cell achieves an exergy efficiency of about 86.5%.