The application of a circulating fluidized bed (CFB) as a gas burner is presented and discussed. The main area of this study is concerned with hydrodynamics, flame stability and temperature distributions of a CFB burner equipped with an internal nozzle burner in the bottom of the riser. Several kinds of solids are tested by changing such operational and design parameters as the ratio of air and fuel flow from the internal nozzle burner to the total flow, the solid circulation rate and the pre-heating temperature of solid particles. The hydrodynamics and flammable region are made clear and the circulation of particles has a significant effect on the bed temperature and temperature gradient in the combustion chamber.