| 摘要 |
PURPOSE: To prevent formation of a pulverized coal deposit layer due to sticking of pulverized coal by specifying an angle formed by a slide face and a rake face of a concentration control ring, an angle formed by the slide face and a diffusing face thereof and an angle formed by the diffusing face and a straightening face thereof respectively. CONSTITUTION: A concentration control ring 31 is put slidably on the outer circumference of a burner inner tube 6 and has a slide face 24 coming into contact with the outer circumference of the burner inner tube 6, a rake face 25 rising from the burner rear end side of the slide face 24, a diffusing face 26 rising from the burner fore end side of the slide face 24 and a straightening face 27 provided on the outer circumference side of the slide face 24 and connecting the rake face 25 and the diffusing face 26. An angleαformed by the slide face 24 and the rake face 25 is made 40-50 deg. and an angleβformed by the slide face 24 and the diffusing face 26 is made an angle of repose of pulverized coal substantially (about 60 deg.), while an angleγformed by the diffusing face 26 and the straightening face 27 is made about 90'. According to this constitution, the pulverized coal getting over the concentration control ring 31 is prevented completely from sticking to this ring and, accordingly, no deposit layer of the pulverized coal is formed on the concentration control ring 31.
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