Fuel cell system with mixer/eductor

摘要

A fuel cell system containing a mixer/eductor for reducing the pressure difference between the gases in the anode and cathode-sides of a fuel cell stack. The mixer/eductor is placed at the mixing point between the anode tail or exhaust fuel gas and the fresh air or oxidant supply gas inlet. The incoming oxidant pressure is converted to a high momentum stream to form a suction on the fuel exhaust gas. This suction compensates for pressure losses in the gas piping and the oxidizer used to burn the exhaust fuel gas resulting in substantial balancing of the anode and cathode-side gas pressures. The mixer/eductor can be in the form of an axial or annular jet pump unit, both of which are advantageous in aggressively mixing the fuel exhaust gas with the incoming oxidant or air. The mixer/eductor geometry can be varied to provide the proper suction to balance pressures over a chosen range of operating conditions. Additionally, the incoming fresh air flow rate or an oxidant exhaust recycle flow rate can be varied to actively balance pressures at any operating point.