A mixer/eductor assembly for use with a fuel cell stack, the mixer/eductor assembly mixing and at least partially combusting anode exhaust gas output from an anode-side of the stack and an oxidant supply gas, the mixer/eductor assembly comprising: a first area mixing a first portion of the anode exhaust gas and a first portion of the oxidant supply gas to form a first mixture, the first area being configured to initiate a combustion reaction in the first mixture, a second area coupled with the first area for mixing a second portion of the anode exhaust gas and a second portion of the oxidant supply gas to form a second mixture, wherein the first mixture has a first oxidant to fuel ratio smaller than a second oxidant to fuel ratio of the second mixture, and the first area provides an ignition source to promote continuous combustion of the second mixture.