| 摘要 |
PROBLEM TO BE SOLVED: To uniform substantially the heat transfer of combustion gas from the upstream side to the downstream side of the same by a method wherein a plurality of water tube groups having different densities of heat transfer areas are arranged from the upstream side toward the downstream side of the flow direction of combustion gas in a sequence from the group having a small density of heat transfer area to the group having a large density of the same. SOLUTION: Water-tube walls 1, constituted of a substantially straight-tubular water tubes 1a, arrayed and arranged in one row with an equal interval while being connected by fin type members 6 mutually to block gaps between respective water tubes 1a, are arranged at both sides of a boiler body so as to be in parallel to each other substantially. Predetermined pieces of water tube groups 2, 3, 4 are arrayed in two rows between the water tube walls 1 with an equal interval substantially, while the water tube groups 2, 3, 4 are arrayed along the flowing direction of combustion gas in a sequence from the group having a small density of heat transfer area (a heat transfer surface area per unit length of flow passage of combustion gas) to the group having a large density of the same. According to this method, the deterioration of local heat transfer efficiency can be prevented. |
