A fluidized fuel gas combustor system for a catalytic dehydrogenation process comprising a vessel having a lower portion and an upper portion; a plurality of air injection diffusers located in the lower portion of the vessel; a plurality of fuel gas injection diffusers located on fuel gas distributors disposed in the vessel and spaced apart from and above a plurality of air injection diffusers, wherein the fuel gas diffusers are placed in a manner to maximize even mass distribution of a fuel gas injected through the fuel gas diffusers in the vessel, wherein each fuel distributor comprises a tube having a plurality of fuel gas injection diffusers, one or more optional grid assemblies disposed in the vessel spaced apart from and above the plurality of air injection diffusers and paced apart from and below the fuel gas distributors to maximize even air mass distribution; and one or more grid assemblies disposed in the vessel spaced above the fuel gas distributors is provided.