PURPOSE: To remove the dust bonded and accumulated in the periphery of the spray orifice of a water spray nozzle spraying water to the gas cooling chamber of an urban waste refuse incineration plant.

CONSTITUTION: A drive shaft 12 is supported in a freely rotating, advancing and retreating state by a guide case 11 and a sawlike dust scraping blade 10 is supported at the leading end part of the drive shaft 12 so as to be freely swing and moved from the position becoming parallel to the axis in the longitudinal direction of the drive shaft 12 to the position crossing said axis at a right angle and set to the state parallel to the axis in the longitudinal direction of the drive shaft 12 to be fitted in a nozzle attaching hole 5. A water spray nozzle is inserted in the inner cylinder 9 of a double cylinder after detachment to be fixed thereto and the dust scraping blade 10 is swing in the state crossing the drive shaft 12 at a right angle and, thereafter, the drive shaft 12 is moved in the direction drawn out of the gas cooling chamber 3 while the drive shaft 12 is rotated by a rotary handle 25 to scrape off and remove the dust D bonded and accumulated in the periphery of the spray orifice of the water spray nozzle.