GB574502A - Improvements in steam superheater elements for use in the smoke tubes of boilers - Google Patents

Abstract

574,502. Steam superheater elements. SUPERHEATER CO., Ltd., and HUET, A. P. J. Feb. 4, 1944, No. 2064. [Classes 64 (iii) and 123 (iii)] In a superheater element for location within a boiler smoke tube and comprising an outer annular flow tube 1, formed of two concentric tubes 7, 8, which is connected at one end by a U-bend to an inner return tube 2, one or each of the tubes 7, 8 has, for at least a part of its length, the cross-sectional area of its wall modified, as compared with that of the tube normally employed, so that its mean wall temperature, and consequently longitudinal expansion, will be the same as the other tube. The outer tube 7 may be a plain cylindrical tube with an increased wall thickness and/or provided externally with fins 9 to increase the mean thickness of its wall. Alternatively, or additionally, the inner tube 8 has its wall thickness reduced and/or provided externally with fins 10, the latter increasing the heat transfer from the tube and so reducing its wall temperature. The fins 9, 10 may be straight or helical and also interrupted at intervals. Preferably the central return tube 2 has its wall temperature reduced by reducing its wall thickness and/or by the provision of internal fins 11.