The objective of the proposed anode-offgas recycling (AOGR) concept is to increase the overall electrical efficiency of a propane-based power system with a 300 Wel solid oxide fuel cell (SOFC) stack beyond normal system configuration with partial oxidation (POX) to syngas. Recycling the anode-offgas partially into the reformer provides steam, carbon dioxide and heat for a combined endothermic steam and dry reforming of the propane, thus replacing the POX reaction. Compared to POX mode, the AOGR concept yields considerably more fuel gas for the SOFC from the same amount of propane. The generated fuel gas is nitrogen-free, thus increasing the SOFC performance additionally. An innovative reformer/burner-reactor allows the internal usage of the anode-offgas heat without additional heat transfer units. The hot-gas injector uses the propane bottle pressure to recycle anode-offgas to the reformer. The transition from POX mode, necessary for the system startup, to the AOGR mode requires enhanced control strategies, developed with the support of dynamic simulation. Critical parameters for the system are the minimal oxygen to carbon (O/C) ratio for carbon-free reformer operation, the SOFC power output and fuel utilization, and the injector performance at a given system backpressure. The concept implementation by an interdisciplinary team of researchers resulted in evaluated process units like injector, reformer, SOFC stack, a dynamic model and controls. The experimental investigation of the whole system will follow soon.

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