Abstract: Steam introduced into a turbine casing from a steam inlet is longitudinally divided and each divided steam portion flows in respective first stages which are disposed on the shaft adjacent to each other. The shaft and a plurality of disks which are manufactured independently are made integral by a thermal shrink. In order to reduce the thermal distortion effects on the shaft caused by keys interconnecting the disks and shaft, first key grooves formed on an outer surface of the shaft and an inner surface of the disks of one first stage and a first key closely disposed in the first key grooves are arranged in symmetry with respect to the center of the shaft, to second key grooves formed on an inner surface of the disk of the other first stage with a second key closely disposed in the second grooves. Other preferred embodiments include dummy grooves and keys to balance the thermal distortion effects of the keys interconnecting the disks and shaft.

Abstract: The present stress in the turbine rotor is estimated at each control period, from the steam temperature and pressure at the turbine inlet. In addition, the future turbine inlet steam temperature or pressure is preestimated once every n.sub.T control cycles, for a given speed or load changing rate, making use of data concerning the changing rate of the turbine steam inlet temperature or pressure in relation with the change of the speed or load, which has been obtained by a learning of the past turbine operating condition. This future steam temperature or pressure at the turbine inlet is used as a factor for preestimating the future stress expected to be caused in the turbine rotor. The preestimation of the rotor stress is performed for a plurality of assumed speed or load changing rates. The turbine is controlled at the maximum speed increase-rate or load changing rate which would not cause the future stress preestimated over a given preestimation time to exceed a limit stress.

Abstract: A method and system for effecting control governing of a steam turbine wherein the steam chamber of a first stage nozzle is divided into a plurality of steam compartments, control valves each connected to one of the steam compartments are individually operated for controlling the flow rate of steam introduced into the turbine, and the governing of the nozzle is effected by adjusting the flow rate of steam in accordance with a load. At low load, the degree of opening of the control valves is kept constant and the turbine is driven by steam of a reduced pressure by reducing the pressure of the steam at the inlet of the turbine so as to maintain, in a low load region, the volume flow rate of steam for a high load region. To cope with a change in the value of the load, the degree of opening corresponding to a predetermined change in the value of the load is set beforehand for each control valve.

Abstract: Low pressure turbine installation comprising a casing, at least two groups of turbine stages mounted in said casing, each turbine stage having blades so arranged that a flow of steam passes through the respective turbine stages in contraflow manner, partition means in said casing for separating the opposed final stages of said turbine stages from each other, and steam exhausting means opened in the side walls of said casing in a direction substantially perpendicular to the axis of said turbine, said steam exhausting means being connected to condensers.