Provided is an air cooled combustion furnace system to effectively operate a combustion furnace for generation of heat energy via combustion of a solid fuel so as to optimize thermal efficiency. The combustion furnace system includes a combustion body structure provided with a hopper and having a combustion space for production of heat energy via combustion of a solid fuel, a cooling device integrally formed in multiple layers with the combustion body structure to cool the combustion body structure via distribution of air, a negative pressure induction device to create a negative pressure within the combustion body structure by suctioning air, a fuel supply device, a grate device constructed by coupling a plurality of grate segments to one another and serving to support the solid fuel being combusted, and a clinker removal device to remove clinkers generated during combustion of the solid fuel from the grate device.