Hitachi, Ltd.

Mitsubishi Hitachi Power Systems, Ltd.

Eiji Saito

Kiyoshi Namura

Masakazu Takasumi

Kazuo Ikeuchi

Yoshiaki Yamazaki

Yutaka Yamashita

Masumi Katayose

Takeshi Onoda

Yoshio Shikano

Shigemichi Inoue

Shinya Imano

Jun Iwasaki

Shigeki Senoo

Takeshi Kudo

Tateki Nakamura

Masaki Kitamura

A turbine bucket for a steam turbine low-pressure final stage has an exhaust area exceeding 9.6 mand 13.8 min steam-turbine final-stage buckets for a rated speed 3600 rpm and 300 rpm machines, respectively. The turbine bucket is made of martensite steel. A blade portion of the turbine bucket has a suction surfaceand a pressure surfacewhich are each formed, at a turbine blade root, of three areas consisting of a steam inlet side areawith curvature, a steam outlet side areawith curvature and an approximately straightly formed area located between the two areas.

Turbine bucket

A high-temperature steam turbine plant is of the top turbine type and structured as follows. It comprises a boiler building including a vertical boiler on the top of which a VHT turbine is installed; and a turbine building installed on the ground as a base. The VHT turbine and a generator connected with it are installed on the top of the boiler. The material for the portion of the steam pipe between the boiler building and the turbine building which is exposed to highest steam pressure is austenite steel which contains 50 weight % or more of ferrite steel or Fe. The inlet temperature of the VHT turbine is 675&#xb0; C. or more and its outlet temperature is 550&#xb0; C. or more and 650&#xb0; C. or less.

High-temperature steam turbine power plant

The present invention relates to a turbine bucket to be provided at the low pressure last stage of a steam turbine and an object of the present invention is to provide a turbine bucket in which the adjacent blades are connected without using a connecting member at a blade intermediate portion. In order to achieve the object of the present invention, a turbine bucket of the present invention is formed in such a manner that the blade sectional configuration is twisted from a blade root portion to a blade tip side, and when assuming two axial directions in a blade section of the bucket on horizontal plane and taking one axial direction as X axis and the other axial direction perpendicular to X axis as Y axis, the blade sections at predetermined heights from the blade root portion of the turbine bucket are formed in a range of &#xb1;0.3 mm from respective points defining blade section configurations as shown respectively in chart 1, chart 4, chart 7, chart 10, chart 13, chart 16 and chart 18.

The present invention is a turbine bucket for at the low pressure last stage of a steam turbine and in which the adjacent blades are connected without using a connecting member at a blade intermediate portion. A turbine bucket of the present invention is formed that the blade sectional configuration is twisted from a blade root portion to a blade tip side, and when assuming two axial directions in a blade section of the bucket on horizontal plane and taking one axial direction as X axis and the other axial direction perpendicular to X axis as Y axis, the blade sections at predetermined heights from the blade root portion of the turbine bucket are formed in a range of &plusmn;0.3 mm from respective points defining blade section configurations.

The moving blades of a rotor included in a steam turbine are formed so that the width of a gap between opposite end surfaces of first connecting members of adjacent blades along the direction of rotation of the rotor and the width of a gap between opposite end surfaces of second connecting members of the adjacent blades along the direction of rotation of the rotor are determined so as to make the second connecting members start coming into contact with each other at a rotating speed of the rotor higher than a rotating speed at which the first connecting members of the adjacent blades start to come into contact with each other.

Steam turbine

A steam turbine for use in a thermal or nuclear power plant includes moving blades of a rotor which vibrate as the rotor rotates, inducing an excessive stress in joints of connecting members for connecting the adjacent moving blades and blade portions of the moving blades and damaging the joints. The moving blades are formed so that a width of a gap between opposite end surfaces of first connecting members of adjacent blades along the direction of rotation of the rotor and a width of a gap between opposite end surfaces of second connecting members of the adjacent blades along a direction of rotation of the rotor are determined so as to make the second connecting members start coming into contact with each other at a rotating speed of the rotor higher than a rotating speed at which the first connecting members of the adjacent blades start come into contact with each other.

A steam turbine is provided with moving blades which are affected less by erosion and fretting wear due to water and have a high reliability in strength. The moving blades are twisted moving blades, each provided with a blade portion and a shroud portion formed at its tip and a contact surface between shroud portions connecting adjacent moving blades whereby an extension plane of the contact surface toward the blade back side does not intersect with the blade tip of the blade back side shroud portion.

The total number (M) of plural blades of a blade apparatus is selected so as not to be a prime number and not to be a power multiplier of a prime number. Plural blades are divided into at least a first blade group in which one blade group has the blades of a first integer number (N.sub.1) and a second blade group in which one blade group has blades of a second integer number (N.sub.2). Each of the first integer number (N.sub.1) and the second integer number (N.sub.2) have no common divisor except 1. The total number (M) of plural blades is the product of the first integer number (N.sub.1) and the second integer number (N.sub.2). The blades of the first integer number (N.sub.1) blade group are connected by a first stage connecting member and the blades of the second integer number (N.sub.2) blade group are connected by a second stage connecting member.

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Hitachi, Japan

Eiji Saito