Patent GB-638552-A (GB)
IPC: F22B1/22
Abstract: 638,552. Forced-flow steam boilers ; superheaters. BAILEY, R. W., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd., March 18, 1947. No. 37298/46. '[Classes 123(ii) and 123(iii)] A steam generator comprises an enclosing casing 31, Fig. 1, a cylindrical steamseparating drum located centrally therein, and one or more hollow or tubulous cylindrical water walls 8 . . . 11 extending between inlet and outlet headers 14, 14a and concentrically diposed around said drum to define with the latter an annular gas passage housing a superheater 12. Four water walls are shown, arranged in two pairs with an intermediate combustion chamber 15 which is fitted at one end with a plurality of fuel burners 17; an auxiliary combustion chamber 16, fitted with burners 21, may also be provided. In operation, water is supplied to the generator through an inlet 14d to a header 14c and from thence in succession through an auxiliary water wall 8a, headers 14 with radial connectors 14e, the walls 8...11, headers 14a, a second auxiliary water wall 14f, a header 14h and pipe 14b to the separating drum 1 provided with steam and water outlet pipes 23, 24 respectively, the former leading steam through the superheater 12 to the main outlet 12e. Simultaneously combustion gases from the chamber 15 pass through ports 13 in the walls 10, 11 to a outlet 28, and also through similar ports in the walls 9, 8 to the superheater space where they may mix with gases from the chamber 16 and continue to an outlet 26. The outlets 26, 28 are fitted with adjustable dampers 29, 30 so that the quantities of gases flowing through the two above-mentioned paths may be controlled, this control, together with adjustment of the combustion rates in the main and auxiliary chambers 15, 16, permitting regulation of the boiler output and superheat temperature. Air, or oxygen-rich products from a combustion product generator, is supplied to the combustion chambers respectively through ducts 18, 22, the duct 18 communicating with a compartmented annular header 19 associated with the burners 17 and fitted with valves 20, one to each of said burners. The burners may, however, be dispensed with, the steam generator being fed with combustion gases from an external source. Several modifications are described, and in each the separating drum is provided internally with means, such as nozzles, &c., for maintaining its inner surface wetted and preventing overheating of the wall thereof. For example, Fig. 6 shows. a drum 94 in which some or all of the water-steam mixture from the outlet header is delivered to a conduit 95 which extends longitudinally within the upper portion of the drum and is provided with a series of closely-spaced orifices or nozzles, In order to increase the water capacity of the 'generator, a separate external water reservoir may be associated with the separating drum and connected to it by a conduit, fitted with a valve controlled by a float located within the drum, and also by a pressure-equalising conduit, said reservoir having an outlet pipe, including a circulating pump, leading to the inlet water header of the generator. The generator may be used in the power plant described in Specification 459,365, [Group XXVI]. Specification 605,695 also is referred to.