Kabushiki Kaisha Toshiba

Junichi Tominaga

Shinichiro Ohashi

Naoki Shibukawa

Kenichi Imai

Yoshifumi Iwasaki

Hiroshi Saeki

Daisuke Nomura

Akihiro Onoda

Tomohiko Tsukuda

Sakae Kawasaki

Tadashi Tanuma

Taro Noguchi

Tadayuki Hashidate

A steam turbine in an embodiment includes a casing, a turbine rotor, a rotor blade cascade, a stationary blade cascade, and a spray unit, the rotor blade cascade and the stationary blade cascade being each arranged at a plurality of stages alternately in an axial direction of the turbine rotor. The turbine rotor is housed inside the casing. In the rotor blade cascade, a plurality of rotor blades are arranged in a circumferential direction of the turbine rotor. In the stationary blade cascade, a plurality of stationary blades are arranged in the circumferential direction of the turbine rotor between a diaphragm inner ring and a diaphragm outer ring. The spray unit sprays spray water to a space located upstream from a rotor blade cascade at a final stage among the rotor blade cascades at the plurality of stages inside the casing.

Steam turbine

A steam turbineof an embodiment includes a turbine rotor, rotor blade cascadeshaving rotor blades, stationary blade cascadeshaving stationary blades, and a steam passageformed on a turbine stage, among turbine stages, including the rotor blades each having a blade height equal to or more than a blade height at which a loss generated when a leakage steam flown between a diaphragm inner ringand the turbine rotorjets into a main steam and a benefit brought by increasing the blade height of each of the rotor bladesin accordance with an increase in a flow rate of the main steam by an amount of the leakage steam are cancelled, and leading the leakage steam from an upstream side to a downstream side of a rotor disk

A steam turbineaccording to an embodiment includes: a casinghaving a turbine rotor; a diaphragm outer ringarranged at an inner side of the casing, and having a hollow partinside thereof; a diaphragm inner ringarranged at an inner side of the diaphragm outer ring; and a stationary bladejoined to the diaphragm outer ringby welding and supported between the diaphragm outer ringand the diaphragm inner ring. A non-joint partexisting at a part of a joint partbetween the diaphragm outer ringand the stationary blade, and in which an end part at an outer diameter side of the stationary bladeis not welded to the diaphragm outer ring; and a suction partcollecting waterdroplet or a water film from the non-joint partare included.

A steam turbineaccording to an embodiment includes rotor bladesimplanted to a turbine rotor, stationary bladesmaking up a turbine stage together with the rotor blades, diaphragm outer ringsincluding an annular extending partsurrounding a periphery of the rotor blades, and supporting the stationary blades, and diaphragm inner ringssupporting the stationary blades. The steam turbinefurther includes an annular slitformed at an inner surface of the diaphragm outer ringbetween the stationary bladesand the rotor bladesalong a circumferential direction, and communication holesprovided in plural at an outer surface of the diaphragm outer ringalong the circumferential direction, communicated to the annular slitfrom the outer surface side, and communicated to an exhaust chamber sucking water films via the annular slit

A steam turbineaccording to an embodiment includes: rotor blade cascades each made up at a turbine rotor; an inner casingwhere the turbine rotoris provided to penetrate; an outer casingsurrounding the inner casing; stationary blade cascades each made up at an inner side of the inner casing; and an annular diffuserprovided at a downstream side of a final turbine stage, formed by a steam guideand a bearing cone, and discharging steam toward outside in a radial direction. An enlarged inclination angle &#x3b8;1 of an inner surfaceof a diaphragm outer ringat the final turbine stage relative to a turbine rotor axial direction is an enlarged inclination angle &#x3b8;2 of an inner surfaceat an inlet of the steam guiderelative to the turbine rotor axial direction or more.

In the axial turbine according to the present invention, a nozzle bladeand/or a movable bladehas a profile in which a throat-pitch ratio 's/t' is maximized at a blade-central portion in height, wherein 's' being a shortest distance between a rear edge of a nozzle blade (movable blade) and a back side of another nozzle blade that is adjacent to the nozzle blade, and &#x201c;t&#x201d; being a pitch of the nozzle blades disposed in the row, minimized in a position between the blade-central portion in height and a blade-root portion and increased from a minimized value to the blade-root portion. This structure enables to provide the axial turbine, which permits to control flow distribution of the working fluid in the height direction of the blade in the passage between the blades of a turbine nozzle unit and a turbine movable nozzle and reduce the blade profile loss and the secondary flow loss at the blade-root portion, thus making a further improvement in the turbine stage efficiency.

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Yokohama, Japan

Junichi Tominaga