GB672362A - Improvements in and relating to steam generators - Google Patents

Abstract

672,362. Forced-flow steam boilers. WEBB, H. W. B. Feb. 16, 1950 [Feb. 25, 1949; May 5, 1949], No. 3979/50. Class 123(ii) A steam boiler comprises a combustion chamber 1, Fig. 1, which is defined by a closely-wound tubular steam-generating coil A consisting of one or a relatively small number of helically-wound tubes, for example, 1A, 1B, as shown, the latter extending continuously from a feedwater preheater 24 each to a steam separator 26 or 27, Fig. 2; the two tubes may additionally be wound to constitute an outer coil C and helical baffles B, D, to provide an elongated passage for combustion gases from a burner 3 at one end of the boiler to a flue 5a at the other end, and each tube has its individual feedwater supply pump 18a or 18b of a capacity in excess of steam requirements. The outlet ends of the tubes 1A, 1B enter the associated separator 26 or 27 tangentially near the upper end thereof below a steam outlet 28, the latter outlets of the two separators having a common steam manifold 29 with a take-off 31; the separators also have excess water outlets 36 opening into the preheater 24. The preheater, Figs. 8 and 9, preferably comprises a casing 37 which locates feedwater tubes 39 extending between end plates 38 and is closed by covers 42, the latter being provided on their inner sides with slots or passages 43 so that the tubes 39 are connected into two parallel circuits in series respectively with inlet conduits 22, 23 leading from the pumps 18a, 18b and with the inlets of the steam-generating tubes 1A, 1B. The maximum water level in the separators and preheater is controlled by a valve 51 in a conduit 52 which extends upwardly from a port 53 in the preheater to a port 54 at the upper end of the separator 27, the valve permitting excess water to pass to a hot-well or feed tank or to waste. In a modified boiler the steamgenerating coils comprise four individual tubes, each with an associated feedwater pump, and there are two superposed preheaters. Specifications 606,208 and 642,157 are referred to.