Steam generator

摘要

A steam generator (2) is described in which a combustion chamber has at least one combustion chamber wall formed by a plurality of longitudinal furnace tubes (10) for passage of an evaporatable flow medium, connected together in gas-tight manner by tube webs. As will be familiar different tubes are likely to be subjected to a heat input in use that varies when the combustion chamber is fired. The tube bores of the furnace tubes are larger where subject to higher heat input than where subject to lower heat input. In particular the tube bores of the furnace tubes are generally larger in the middle region of the combustion chamber wall than at the transversely peripheral regions of the combustion chamber wall.

主权项

1. A steam generator comprising:
a combustion chamber having a polygonal cross-section formed by combustion chamber walls, wherein at least one of the combustion chamber walls of the combustion chamber comprises a plurality of separate furnace tubes that extend in a longitudinal direction of the combustion chamber and is configured to provide a single fluid system for parallel passage of an evaporable flow medium in the furnace tubes in a single same direction with respect to the combustion chamber from a common source to a common outlet of the combustion chamber; tube webs provided between adjacent ones of the furnace tubes which connect the furnace tubes together in a gas-tight manner; wherein the combustion chamber is configured so that the furnace tubes located in a middle region of the at least one combustion chamber wall, as viewed in a direction transverse to the longitudinal direction of the combustion chamber, are subjected to higher heat input levels than the furnace tubes located in end regions of the combustion chamber wall where said combustion chamber wall forms corners regions with adjacent combustion chamber walls when the steam generator is in use; and wherein tube bores of the furnace tubes vary in size in the direction transverse to the longitudinal direction of the combustion chamber along the at least one combustion chamber wall so that diameters of the tube bores of the furnace tubes located in the middle region of the at least one combustion chamber wall are larger than diameters of the tube bores located in the end regions of the at least one combustion chamber wall, wherein the furnace tubes in the at least one combustion chamber wall are such that there is a successive reduction in the tube bore between each adjacent tube from the middle region of the at least one combustion chamber wall towards the end regions of the at least one combustion chamber wall.