| 摘要 |
PROBLEM TO BE SOLVED: To improve the efficiency of a boiler and to miniaturize the boiler by increasing the amount of heat absorption per unit area in a water tube for contact heat transmission, and to smoothly discharge exhaust gas. SOLUTION: In a shell-and-tube once-through boiler, an annular combustion chamber 3 is formed between both water walls 1, 2 by concentrically arranging the two annular water walls 1, 2, and an annular combustion gas passage 8 is formed between both of them by arranging an annular inner wall 7 comprising a water wall, or the like inside the inner water wall 1, and the upper and lower end sections of water tubes 1a, 2a, 7a on the water walls 1, 2 and the inner wall 7 are connected to an upper header 9 and a lower header 10, respectively, so that they can communicate each other. In the shell-and-tube once-through boiler, a heat transfer water tube 12a having a fin 11 is arranged spirally in a posture along the outer-periphery surface of the inner wall 7 in the combustion gas passage 8. A fin 18 is mounted to the outer surface of the water tubes 1a, 7a located at the inner surface side of the inner water wall 1 and at the outer surface side of the inner wall 7 while the fin 18 is being inclined. Further, the upper header 9 is formed annularly and an exhaust gas exhausting port 15 communicating with the combustion gas passage 8 is formed at the center. COPYRIGHT: (C)2006,JPO&NCIPI
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