Device for supply of secondary air, and boiler with the device

Solid-fuel combustion apparatus, comprising a thermally insulated wall structure defining an upwardly open primary combustion chamber, means disposed in said primary combustion chamber for supporting a solid fuel for combustion, means for supplying primary combustion air to said primary combustion chamber, and a secondary combustion air supply device mounted to said wall structure above said primary combustion chamber, said secondary combustion air supply device comprising a frusto-conical shell open at both axial ends and oriented with its larger axial end opening to said primary combustion chamber, said shell having a spaced inner and outer walls defining a frusto-conical air space therebetween, with said inner and outer walls being circumferentially sealed to one another near both axial ends of said shell and with said inner wall being perforated, and secondary air supply duct means connected in communication with said air space of said frusto-conical shell for supplying secondary combustion air thereto for ejection through the perforations of said inner wall into an exhaust gas stream generated by the solid fuel burning in said primary combustion chamber.