A new emergency shutdown procedure for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide means of quantifying risk mitigation strategies.
An open-loop system analysis regarding the dynamic effect of bleed air, cold air by-pass and load bank is presented in order to evaluate the combination of these three main actuators during emergency shut-down. In the previous Hybrid control system architecture, catastrophic compressor failures were observed when the fuel and load bank were cut-off during emergency shut-down strategy. Improvements were achieved using a non-linear fuel valve ramp down when load bank was not operating. Experiments in load bank operation show compressor surge and stall after emergency shut-down activation. The difficulties in finding an optimal compressor and cathode mass flow for mitigation of surge and stall using these actuators are illustrated.