| 摘要 |
PURPOSE:To improve the heat exchanging efficiency and simplify the manufacture of the boiler by a method wherein a coil-shape heat transfer tube, arranged at the upper part of flue in a boiler cylinder, is formed in the section thereof so as to be longer in the passing direction of combustion gas and is wound into the shape of scroll. CONSTITUTION:Combustion gas passes a space between the coil-shape heat transfer tube 2 and a heat insulating member 3, a combustion chamber 4 and spaces between the heat transfer tubes 5, wound into the scroll shape and whose sectional diameter is longer in the passing direction of the combustion gas, as shown by arrow signs A, while the heat thereof is exchanged with the heat of water which flows into the arrow signs B. The heat transfer area may be increased and the time of stagnation of the combustion gas may be lengthened by shaping the section of the heat transfer tube 5 into ellipse or the like in which the diameter is longer in the passing direction of the combustion gas, therefore, the heat exchanging efficiency may be improved. The number of parts and man- hour for working may be reduced and, therefore, the manufacture thereof may be simplified. |
