GB105933A - Improvements in or relating to Steam Turbines. - Google Patents

Abstract

105,933. Baumann, K. Feb. 4, 1916. Axial-flow type; casings; exhaust, disposing of; mounting and supporting.-R e l a t e s mainly to improved constructions of turbine exhaust casings for axial-flow turbines, said casings conducting the exhaust steam from the last row or rows of moving blades to the exhaust outlet or condenser, and the invention is particularly applicable to multiple exhaust turbines of the kind described in Specification 14053/15. In an ordinary axial-flow turbine, Figs. 1 and 2, the whole of the exhaust steam leaving the moving blades 8, according to the invention, is deflected outwards into a substantially radial direction by the casing wall 10 and then conducted by guide walls 11 in a number of segmental portions outwardly away from the turbine axis in a direction substantially transverse thereto. The exhaust outlet 6 is long and narrow, thus distributing the steam over the whole length of the condenser 7, which may be supported directly from the outlet 6, no expansion joint being necessary; or an additional resilient support may be provided for the condenser. With this construction of exhaust casing, sufficient strength and rigidity is obtained to enable the turbine casing to be supported on feet 13, 14 located at the two ends only of the exhaust casing, these feet being advantageously strengthened by transverse stiffening-webs preferably formed as continuations of the guide walls 11. The walls 11 may be shaped to involute curves, and may be discontinued when portions of steam in adjacent passages are flowing in the same direction. In a modification, Fig. 5, wherein the axial length of the exhaust casing is increased and the width reduced, the width increases as shown towards the outlet, the outer portions of the lower half of the exhaust casing are made separately, and the supporting feet 13 14, Fig. 7, are made larger, the feet 14 serving to support the bearing at the exhaust end of the turbine. In a further application, to a turbine having a duplex flow towards the middle, a central guide is provided for deflecting outwardly the exhaust steam. Fig. 10 shows the invention applied to a multiple-exhaust turbine of the kind described in Specification 14053/15 and wherein the steam flows to exhaust from the whole area. of the moving blades 8 and from the cuter portions of the moving blades 8<b>, 8<c>, 8<d>. The steam is deflected into a substantially radial direction by the wall 10 in the case of the blade discharge 8, by the shrouding 17 and curved guide 23 in the case of the outer blade discharge 8<b>, and by the shroudings 18 and 19 and guides 24 and 25 respectively in the cases of the outer blade discharges 8<c>. 8<d>. The steam leaving all the rows of blades 8, 8<b>, 8<c>. 8<d> is divided circumferentially into segmental portions by guide walls 11 as previously described. The construction and arrangement of the guide passages may be modified to secure various advantages, as, for example, a compact outlet. In a multiple-exhaust turbine, an exhaust of the kind described in Specification 2848/14 or an ordinary type of exhaust casing may be used to conduct away the steam from the final row of exhaust the steam flowing from the earlier rows being led away by an exhaust constructed according to the present invention. To secure maximum strength and rigidity near the outlet of the exhaust casing, the guide walls therein are formed as far as possible as continuations of one another. The supporting feet of the turbine may be located at the sides only or at the sides as well as at the ends of the exhaust casing, which may be strengthened by stiffening webs. Several constructions are described wherein the guide walls 11 conduct the steam to two condensers arranged at various angles in a plane at right-angles to the plane of the turbine shaft. Fig. 23 shows two condensers 7 with their axes parallel to that of the turbine 2; alternatively, the walls 11 may be continued down to a single condenser. Where two condensers are provided, passages 40 fitted to ensure equality of vacuum and to allow either condenser to be shut down for cleaning &c. without stopping the plant. In the form shown in Fig. 25, the enclosing walls of the exhaust casing are of substantially involute shape. The end walls diverge from the centre outwards, and may have a conical form.