| 摘要 |
A package water tube boiler has offset upper and lower steam and water drums located adjacent its opposite side walls, with a generally square combustion chamber between the drums. Connecting the drums are generally L-shaped riser and downcomer tubes including convection tubes and radiant tubes extending in vertical and horizontal runs along the sides, top, and bottom of the combustion chamber. The tubes, especially the inboard radiant tubes, are configured, and their entrances and exits to and from the drums are located, so as to permit increased efficiency and steam generation capacity without increasing the package boiler's outside dimensions, to shield the drums from thermal radiation emanating from the combustion chamber, to locate the boiler's center of gravity equidistant from its side walls, and to fix the upper drum to and support it by the boiler's end walls. Preferably, the relationships between the radiant tubes and the upper drum are such that the inboard radiant tubes in their generally horizontal run extend past the vertical plane including the drum's longitudinal axis by a distance of at least 60% of the drum's radius, the inboard radiant tubes bend in an acute angle just before entering the drum, the distance between the inboard radiant tubes and the drum are substantially less than the drum's radius, and the entrances of the radiant tubes in the drum are spaced radially from those of the convection tubes.
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