Cathode Temperature Management During Hybrid System Startup Available to Purchase

Management of air flow through the cathode of a hybrid Solid Oxide Fuel Cell/Gas Turbine generation system is of critical importance for the survival of the fragile fuel cell. The cell must be protected from excessive thermal gradients within each cell/stack and from pressure differences between the anode and cathode. While significant modeling of hybrid system performance has been done for the steady state case, only modest attention has been given to startup and shutdown of a hybrid system. Various researchers have performed modeling studies on SOFC during startup, and have concluded that thermal ramp-up times can require anywhere from less than one hour to more than four hours to avoid thermal shock and potential destruction of the fuel cells. For hybrid systems employing single spool turbine/compressor systems, gradual ramping will be difficult because the rotating components must be brought up to full operating speed quickly to avoid stalling the compressor. This paper proposes a strategy for accommodation of the conflicting startup constraints using both experimental data from the NETL HyPer system and simulation approaches.