An oxidizer that is usable with a fuel cell includes a catalyst, an inlet to communicate an oxidant flow, an injection tube to communicate an anode exhaust flow, a mixing tube and a divergent nozzle. The injection tube communicates the anode exhaust flow from the fuel cell into the oxidizer to produce a combined flow in which the anode exhaust flow is oriented in substantially the same direction as the oxidant flow and surrounded by the oxidant flow. The mixing tube is connected to the inlet to receive the combined flow and mix the oxidant flow and the anode exhaust flow mix together to produce a mixed flow. A cross-sectional flow area of the mixing tube is sized to prevent flashback. The divergent nozzle communicates the mixed flow to the catalyst.