a burner nozzle assembly includes : a nozzle plate having an anode off - gas nozzle at the center of the nozzle plate and a plurality of oxidation fuel nozzles surrounding the aog nozzle ; and a channel unit coupling the aog nozzle with an aog introducer to allow an aog to flow therebetween and coupling the oxidation fuel nozzles with an oxidation fuel introducer to allow an oxidation fuel to flow therebetween .