To improve the combustion efficiency of chaff by providing an air passage wherein a pair of blowing-out nozzles in the tangential direction to feed air which forms a spiral air stream at the upper edge section of a conical body, by hitting a shade section being vertically hung under an approx. shade-form from the base of a central downward blowing-out nozzle, and a lid body having a built-in heat- exchanger.

A lid body 8 has a short cylindrical shape having a top, which is detachably placed on the upper end opening of a cylindrical container 1 having a bottom, and has a built-in air passage 10. In the air passage 10, a central downward blowing-out nozzle 11, which is located between two projecting walls 7 and a V-shaped body 5 provided on a conical body 2, and feeds air to a flat surface recess 21 section of the V-shaped body 5 from the top, is vertically hung. Also, a pair of blowing-out nozzles 12 in the tangential direction to feed air which forms a spiral air stream at the upper edge section of the conical body 2, by hitting a shade section 19 being vertically hung under an approx. shade-form from the base of the central downward blowing-out nozzle 11, is provided in a manner to face diagonally downward. An air feeding by the air passage 10 is performed by a blower 9 which is set on the end section of an air furnace 10. A heat-exchanger 15 is built in the lid body 8.