Transient Modeling for Assessing Catalytic Combustor Performance in Small Gas Turbine Applications

Abstract

The development of lean-premixed catalytic reactors for ultra-low emissions combustors in gas turbines presents many design and operability challenges that are not addressed with conventional steady-state reactor models with one-step chemistry mechanisms. These challenges include transient light-off from low temperatures, catalyst deactivation, and hysteresis in catalytic activity. To address these issues, a transient 1-D reactor model with a validated multi-step surface chemistry mechanism has been developed to explore such behavior in catalytic combustors. The surface chemistry sub-model has been incorporated for investigating lean catalytic combustion of CH4 on Pd-based catalysts. The current study investigated the effects of operating conditions — such as pressure, inlet temperature, and velocity — on catalytic reactor ignition and deactivation. The transient modeling provides curves for reactor light-off for a range of inlet pressures and velocities and reveals conditions wherein Pd-catalyst undergoes reduction/deactivation. Model results are compared with some experimental measurements and implications for catalytic combustor design and operation for gas turbine applications are discussed.