Control of steam turbine shaft thrust loads

Claim 1

In a single axial flow overhung steam turbine of the type having a high pressure input, a low pressure exhaust cavity, a rotor casing defining a steam passage from said input to said exhaust cavity, a rotor shaft supported for rotation within said casing and having a downstream end disposed in said exhaust cavity, a rotor mounted on said rotor shaft in flow communication with said steam passage from said input to said exhaust cavity for converting steam pressure into rotational force, an improved seal and bearing arrangement comprising: (a) an exhaust diffuser mounted to said rotor casing within said exhaust cavity defining a pocket having an open end adjacent said downstream end of said rotor shaft and a closed end downstream from said open end; (b) a first circular seal member sealingly mounted to the open end of said pocket; (c) a second circular seal member sealingly mounted to the downstream end of said rotor shaft for sealing rotational engagement with said first circular seal member so that said pocket is sealed from said exhaust cavity; (d) a duct means for providing the interior of said sealed pocket with atmospheric pressure, whereby unbalanced axial force on said rotor shaft is reduced; (e) a split housing assembly detachably mounted in a fixed relationship to said rotor casing; (f) a split journal bearing detachably mounted to said split housing for providing radial load bearing support to said rotor shaft, whereby said journal bearing may be replaced without removing said rotor shaft; and (g) a thrust bearing detachably mounted to said split housing for providing axial load bearing support to said rotor shaft, whereby said thrust bearing may be replaced without removing said rotor shaft.