High efficiencies with low fuel utilization and thermally integrated fuel reforming in a hybrid solid oxide fuel cell gas turbine system. (15th August 2020)

• Record Type: Journal Article
• Authors: Chen, Hao; Yang, Chen; Zhou, Nana; Farida Harun, Nor; Oryshchyn, Danylo; Tucker, David
• Is Part Of: Applied energy. Volume 272(2020)
• Publication Date: 2020-08-15
• Subjects: Low fuel utilization -- Natural gas -- SOFC-GT systems -- System study -- Thermally integrated reforming; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2020.115160
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: System study of a 100 kW natural gas fired SOFC/GT hybrid was conducted. High efficiency design with low fuel utilization ( U f ) SOFC was explored. 50 design cases with different SOFC U f and fuel pre-reforming rates were evaluated. Peak system efficiency was found at SOFC U f around 60% in this hybrid. Operational constraints were considered to identify feasible design points. Abstract: Solid oxide fuel cell (SOFC) - gas turbine (GT) systems have a potential to achieve 70% efficiency, which with high fuel flexibility and high part load efficiency, makes this hybrid a promising technology for the next power generation systems. To realize the high efficiency and reduce the capital cost, most studies focus on high fuel utilization SOFC stack design with internal fuel reforming configuration in SOFC-GT hybrids. None of them have considered low fuel utilization SOFC design in the hybrid system, which could extend the SOFC lifetime and also decrease the capital cost from fuel cells, accelerating the commercialization of fuel cell technologies. To fill this research gap, this work examined the system performance of a pressurized natural gas hybrid SOFC-GT system with a thermally integrated fuel reforming process. Specifically, system cycle analysis was performed in this work to explore the feasibility of achieving high efficiencies with low SOFC fuel utilizations. An equilibrium reformer model and a one-dimensional SOFC model were employed to represent the SOFC system, while balance of plant model was built in Ebsilon® to simulate the associated performance of recuperated gas turbine cycle. With the thermally integrated system configuration, 70% efficiency could be reached at 50% SOFC fuel utilization with a high fuel pre-reforming rate (only ~ 5 mol% CH4 at anode inlet). Low fuel utilization operations with high fuel pre-reforming rates provided higher design flexibility without violating any operational constraints while maintaining a high system efficiency as compared to on-anode reforming.