To provide a means for supplying a combustion flame with a desired heat quantity distribution in a rotary kiln.

A nozzle tip 12 is provided with a combustion flame shaping means for shaping the outer shape of the combustion flame so that a combustion length L of the combustion flame becomes short and a maximum diameter D of a combusting range of the combustion flame becomes large. The combustion flame shaping means is constituted by forming a jetting portion 123 of the nozzle tip 12 into a shape of funnel or by adding a spindle-shaped member to the nozzle tip 12. The outer shape of the combustion flame can be readily controlled by preparing a plurality of nozzle tips capable of giving a variety of shapes to the outer flame, and changing the nozzle tips.