Steam turbine

Patent metadata

Field	Value
Publication number	US-9850781-B2
Application number	US-201414315837-A
Country	US
Kind code	B2
Filing date	Jun 26, 2014
Priority date	Jun 27, 2013
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A steam turbine 10 according to an embodiment includes rotor blades 22 implanted to a turbine rotor 21 , stationary blades 26 making up a turbine stage together with the rotor blades 22 , diaphragm outer rings 23 including an annular extending part 24 surrounding a periphery of the rotor blades 22 , and supporting the stationary blades 26 , and diaphragm inner rings 25 supporting the stationary blades 26 . The steam turbine 10 further includes an annular slit 40 formed at an inner surface of the diaphragm outer ring 23 between the stationary blades 26 and the rotor blades 22 along a circumferential direction, and communication holes 50 provided in plural at an outer surface of the diaphragm outer ring 23 along the circumferential direction, communicated to the annular slit 40 from the outer surface side, and communicated to an exhaust chamber sucking water films via the annular slit 40.

First claim

What is claimed is:

1. A steam turbine where wet steam flows in a turbine stage in low-pressure,
comprising:
rotor blades implanted in a circumferential direction to a turbine rotor provided to penetrate in a casing;
stationary blades provided at an immediate upstream side of the rotor blades in the circumferential direction, and making up a turbine stage together with the rotor blades;
diaphragm outer rings provided inside the casing, each including an annular extending part surrounding a periphery of the rotor blades, and supporting the stationary blades from outside in a radial direction;
diaphragm inner rings supporting the stationary blades from inside in the radial direction;
an annular slit formed at an inner surface of the diaphragm outer ring between the stationary blades and the rotor blades along the circumferential direction; and
communication holes provided in plural at an outer surface of the diaphragm outer ring along the circumferential direction, the communication holes communicating to the annular slit from an outer surface side of the diaphragm outer ring, the communication holes connecting to the annular slit directly, the communication holes communicating to a suction part sucking liquid via the annular slit, the communication holes inclining relative to a radial line extending from a center axis of the turbine rotor in the radial direction at a cross section perpendicular to the turbine rotor axis direction, the communication holes inclining toward a reverse direction to a turning direction of the wet steam passed through between the stationary blades.

2. The steam turbine according to claim 1 ,
wherein an inclination angle of the communication hole relative to the radial line is more than “0” (zero) degree and 75 degrees or less.

3. The steam turbine according to claim 1 ,
wherein when the communication hole is formed by a round hole, a pitch of the communication hole in the circumferential direction is P, a diameter of the round hole of the communication hole is D, and the inclination angle of the communication hole relative to the radial line is θ, a value of P/(D·secθ) is five or less.

4. The steam turbine according to claim 1 ,
wherein when a groove depth of the annular slit in the radial direction is L, a groove width of the annular slit in the turbine rotor axis direction is W, a value of LW is three or more.

5. The steam turbine according to claim 4 ,
wherein the groove width W is 10 mm or less.

6. The steam turbine according to claim 1 ,
wherein the communication hole is formed along a radial line extending from the center axis of the turbine rotor in the radial direction at a cross section perpendicular to the turbine rotor axis direction.

7. The steam turbine according to claim 1 ,
wherein an end part at an upstream side of the annular slit facing the inner surface of the diaphragm outer ring is on a circumference including an intersection point between a trailing edge of a blade tip of the stationary blade and the diaphragm outer ring.

8. The steam turbine according to claim 1 ,
wherein at a trailing edge of the stationary blade positioning at 90% or more of a blade height from a blade root, the trailing edge extends as it goes to a blade tip.

9. The steam turbine according to claim 1 ,
wherein an end part at an upstream side of the annular slit facing the inner surface of the diaphragm outer ring is chamfered.

10. The steam turbine according to claim 1 ,
wherein an acute angle α made up of the turbine rotor axis direction and the inner surface of the diaphragm outer ring where the annular slit is formed is smaller than an acute angle β made up of the turbine rotor axis direction and the inner surface of the diaphragm outer ring at an upstream side than the annular slit.

11. The steam turbine according to claim 10 ,
wherein the acute angle α is “0” (zero).

12. The steam turbine according to claim 1 ,
wherein the annular slit is formed in plural stages in the turbine rotor axis direction between the stationary blades and the rotor blades.

13. The steam turbine according to claim 1 ,
wherein the diaphragm outer ring where the annular slit is formed is included in a turbine stage where wet steam flows.

Assignees

• Toshiba Kk

Inventors

• Shibukawa Naoki
• Tsukuda Tomohiko
• Tominaga Junichi
• Ohashi Shinichiro

Classifications

• F05D2260/602

  Drainage · CPC title

• F01D9/047

  Nozzle boxes · CPC title

• F01D25/32 Primary

  Collecting of condensation water; Drainage {; Removing solid particles} · CPC title

• F01D9/041

  using blades (F01D5/148 takes precedence) · CPC title

• F01D1/00

  Non-positive-displacement machines or engines, e.g. steam turbines (wit working-fluid flows in opposite axial directions for balancing axial thrust F01D3/02; with other than pure rotation F01D23/00; turbines characterised by their use in special steam systems, cycles, or processes, regulating devices therefor F01K) · CPC title