GB605695A - Improvements in and relating to steam generators - Google Patents

Abstract

605,695. Forced-flow steam boilers; headers. BAILEY, R. W., and METROPOLITAN VICKERS ELECTRICAL CO., Ltd. Oct. 5, 1940, Nos, 6206 and 8055. [Class 123(ii)] A steam boiler comprises at least one pair of closely-spaced tubulons or hollow walls 1, but preferably two cylindrical and coaxial pairs, which are arranged around a furnace chamber provided at its upper end with a burner 46, the two pairs being connected to end headers 10, 10a and 11, 11a respectively for the circulation of water therethrough, in series or in parallel, and also spaced to define a flue 6 accommodating a superheater 7. In the form shown the walls are constituted by tubes 1 having integral webs 2 with the abutting edges of adjacent webs welded together at 3, Fig. 3, but the webs are cut away at the lower and upper ends alternately of successive walls so as to enable the combustion gases from the furnace to flow therebetween, in the direction of the arrows, to an outlet 48. Filler strips 4, fixed to the webs 2 by screws 5, are also fitted between the tubes on the sides of the walls bounding the superheater flue space 6. The superheater 7 is preferably formed in units each located in one of a number of longitudinal flues into which the space 6 is divided by radial refractory partitions. the inlets 7a and outlets 7b of the units being connected to annular saturated and superheated steam headers 34, 35 respectively. A steam separator 27 is associated with the boiler and has pipe connections 26 from an annular steam and water space 22, extending upwardly from the water header 10, and like connections 38a, 38b to the saturated steam header 37. The water 11 is also provided with a feed water inlet 39, the lower water headers 10a, 11a with radical communicating pipes 42, and the header 35 with one or more outlets 36. The arrangement is such that feedwater under pressure supplied by a pump, not shown, and pipe 39 to the header 11 will circulate through the outer pair of tubulous walls, lower headers 10a, 11a and inner walls, in succession, to the header 10 and its steam and water space 22, from which the steamwater mixture is led to the separator 27 through the pipes 26, the steam returning by the pipes 38a, 38b to the superheater inlet header 34 and thence through the superheater to the outlet header 35 and the separated water being led to the feedwater tank for recirculation through the boiler. Air-laden gas and fuel are supplied to the burner 46 by pipes 47, 47a respectively and the lower end of the furnace chamber, opposite the burner, is closed by a cover plate 43 upon which is mounted a coiled pre-heating water pipe 44. The water headers, Fig. 4, are preferably each formed in two similar counterpart channel sections 12, 13 which may be machined from the solid and have edges adapted to fit and to be welded together at 14 in a plane substantially perpendicular to the axes of the tubes connected thereto. The wall of the header, opposite the wall to which the tubulous walls are connected, is provided with large oval and small round tube cleaning holes 17, 18, closed by readily removable covers, and headers in a common plane may be united by radial spacing plates 15 welded therebetween. In a modification, Fig. 7, in which the boiler is associated with a turbine 68 having high and low pressure stages separated by a diaphragm 69, the superheater tubes 7 extend about half-way only along the flue 6 and reheater tubes 65 to and from headers 66, 67, located.at the opposite end of the boiler and in the steam circuit between the two turbine stages, project towards them. Further the reheater tubes may be replaced by two groups both of which may be used as superheaters, in series with the group 7, or one as a superheater and the other a reheater. Specifications 459,365 and 581,960, [both in Group XXVI], are referred to.