| 摘要 |
PROBLEM TO BE SOLVED: To enhance removing ability for a sticking substance with no drop of boiler efficiency or nozzle life. SOLUTION: A nozzle 17 is provided to a closing part at the tip of a tabular lance 1, and a jet air supplied into the lance is,jetted through the nozzle 17, removing the substance (ash) sticking/deposited on a heat transfer part through the jet collision. The nozzle 17 comprises an expanding part 20 which expands from a round part at an entrance part 19 toward an outlet. Here, the structure of the nozzle 17 is optimized so that conditions specified below are all met; 1.3<=L/D<=2.1, 10 deg.<=θ<=17 deg., 0.4<=R/D<=0.7 where a divergent angle of the expanding part 20 isθ, a radius of curvature of the entrance part 19 which is an air flow-in part is R, an effective length from a round part of the entrance part 19 to the tip outlet is L, and an aperture (throat diameter) of a nozzle is D.
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