JP2000274207A - Turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve turbine efficiency of a turbine having a structure than an outlet flow of a rotor blade lattice is formed in the axial direction and that a diffuser is connected to the rotor blade lattice by providing two lines of variable stator blade lattice near the outlet of the rotor blade lattice, so as to change a turning component of the flow in the axial direction. SOLUTION: A turbine 1 is formed of a fluid inlet nozzle 1a, a turbine casing 2, and a turbine rotor 3 provided with a rotor blade 4 in the periphery thereof, and the rotor blade 4 is formed by combining several ten blades having a blade- like cross section into a ring. A variable stator blade 5, provided in a diffuser 8 near an outlet of the rotor blade lattice 4, is similarly formed by combining several ten blades having a blade-like cross section into a ring and formed of two lines of an upstream side variable stator blade 6 and a downstream side variable stator blade 7. Since the diffuser 8 of the outlet of the rotor blade lattice 4 is provided with the two variable stator blade lattice capable of freely changing the set angle, a turning component of the fluid is reduced, and the speed of the fluid can be converted to pressure, and turbine efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine in which a flow of a fluid at an outlet of a turbine blade flows in an axial direction.

[0002]

2. Description of the Related Art A turbine is a method in which a fluid is applied to a row of rotor blades and the energy of the fluid is converted into rotary motion and taken out as rotary machine work. It constitutes a cascade. The fluid at the outlet of the rotating blade row that has performed rotary machine work in the rotating blade row is designed so that it does not have a swirl component in the rotational direction at the design point, but has a swirl component when used away from the design point. It may come out as it is.

[0003] For example, in a steam turbine, high-speed exhaust steam discharged from a moving blade row outlet, in which steam works on a moving blade provided on a turbine rotor, is passed through a diffuser connected to the moving blade row. The velocity energy is recovered and converted into pressure energy to restore the pressure, thereby lowering the pressure at the rotor blade row outlet, increasing the heat drop to be used, and improving turbine efficiency.

As a technique for reducing the pressure at the blade row outlet, there is a technique for providing a flow straightening plate in a diffuser connected to the blade row to straighten the flow of the working fluid exhausted from the blade row outlet. In a diffuser provided with a flow straightening plate, when the pressure and flow rate of exhaust steam from the moving blade row change, the outflow angle of exhaust steam from the moving blade row outlet changes, so that the straightening plate is separated at a point other than the design point.

In order to prevent this separation, a flow straightening plate is provided rotatably and is rotated in a direction parallel to the outflow angle of the working fluid exhausted from the moving blade row outlet so as to be parallel to the working blade exhaust from the moving blade row outlet. A technique has been disclosed in which flow separation does not occur even when the outflow angle of the working fluid changes (Japanese Patent Laid-Open No. 4-419).
07).

FIG. 4 is a partial sectional view of a steam turbine provided with an exhaust diffuser disclosed in Japanese Patent Application Laid-Open No. 4-41907. In the figure, a is a bucket row. b is the rotor row a
It is a turbine rotor provided with. c is a guide ring,
There are a plurality of stages of stationary blade rows forming a blade stage with the moving blade row a. d is a stationary blade row. e is a diffuser provided following the outlet of the bucket row a, and f is a turbine casing. g is a pin h between the inner cone i and the outer guide j
This is a rectifying plate that is provided so as to be rotatable so as to be parallel to the flow direction of the exhaust steam. k is a labyrinth seal.

[0007]

However, the straightening vane of the steam turbine disclosed in Japanese Patent Application Laid-Open No. 4-41907 is rotated in a direction parallel to the outflow angle of the working fluid exhausted from the blade row outlet. It is operated so that flow separation does not occur even if the outflow angle of the working fluid from the blade row outlet changes, but it does not convert fluid energy into pressure energy. The turbine is designed so that the fluid at the outlet of the moving blade row, which has performed rotary machine work in the moving blade row, does not have a swirl component in the rotational direction at the design point. However, the swirl component is discharged from the diffuser without being converted into pressure, and the purpose of the diffuser cannot be achieved in that the pressure at the blade row outlet is reduced to increase the utilized thermal head.

SUMMARY OF THE INVENTION The present invention has been devised to solve the above-mentioned problems, and in which a swirling component of a fluid is turned (bent) in the axial direction by a diffuser at the outlet of a moving blade row, and the swirling component is diffused. It is an object of the present invention to provide a turbine in which the pressure is recovered as a pressure in a turbine blade row and the pressure difference between the inlet and outlet of the moving blade row is increased so that the turbine efficiency is improved even when the turbine blade is used out of design points.

[0009]

According to the present invention, in a turbine in which an outlet flow of a moving blade row is an axial flow and a diffuser is connected to the moving blade row, an outlet of the moving blade row is provided. A turbine is provided in which two variable stator vane rows are provided in the vicinity to turn the swirling component of the flow in the axial direction.

Next, the operation of the present invention will be described. When the turbine is used at the design point, the flow at the blade row exit has no swirl component, and therefore the two rows of variable vanes are both axially oriented. When using the turbine out of the design point, the variable vanes on the upstream side should be oriented in the direction corresponding to the swirl angle of the rotor row outlet flow, and the variable vanes on the downstream side should be oriented in the axial direction. deep. Therefore, the swirling component of the fluid when the fluid leaves the bucket row is turned in the axial direction, is collected as pressure by the diffuser, and the pressure difference between the inlet and outlet of the bucket row can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a partial sectional view of the turbine of the present invention. FIG. 3A is a development view of the turbine, and FIG. 3B is a view showing a state in which the flow of the fluid is turned by the variable vanes.

1 and 3, reference numeral 1 denotes a turbine, and reference numeral 1a denotes a fluid inlet nozzle of the turbine 1. 2 is a turbine casing. Reference numeral 3 denotes a turbine rotor having a rotor blade 4 disposed on the outer periphery. The moving blade 4 forms a moving blade row by combining tens of blades having an airfoil cross section in an annular shape.

5 is a diffuser 8 near the exit of the bucket row 4.
In the same manner as the moving blades 4, the variable vanes having dozens of blade-shaped cross sections are annularly combined to form two rows of an upstream variable stationary blade 6 and a downstream variable stationary blade 7. ing. Reference numeral 6a denotes a rotating pin of the upstream variable stationary blade 6, which is provided downstream of the center of the upstream variable stationary blade 6 in the width direction. Reference numeral 7a denotes a rotation pin of the downstream variable stationary blade 7, which is provided upstream of the center of the downstream variable stationary blade 7 in the width direction. Rotating pins 6a, 7
When the variable a is provided in this manner, when the variable stationary blade 5 is rotated, the position of the rear edge of the upstream variable stationary blade 6 and the position of the front edge of the downstream variable stationary blade 7 are not so far apart. Upstream variable stationary blade 6 and downstream variable stationary blade 7
Sets the angle of the variable vane 5 based on the fluid flow calculated in advance according to the operating conditions. In order to set the angle, a drive device including a pinion (not shown) provided on each of the rotating pins 6a, 7a of the upstream variable stationary blade 6 and the downstream variable stationary blade 7, and an annular rack (not shown) meshed with the pinion. The rotation is performed by using Variable vane 5
Are arranged in two rows of an upstream variable stationary blade 6 and a downstream variable stationary blade 7, so that the upstream variable stationary blade 6 is set at an angle corresponding to the swirl angle of the exit flow of the moving blade 4, and By setting the angle of the variable stationary blade 7 in the axial direction, the turning component can be easily bent in the axial direction. Arrows 9, 10,
10a shows the flow of the fluid. Reference numeral 15 denotes a fluid turning area.

FIG. 1B is a diagram showing a difference in pressure at the blade row outlet when a variable stator blade is provided and when no variable stator blade is provided. The left side shows the turbine inlet side, and the right side shows the outlet side. Is shown. In the drawing, reference numeral 11 denotes a case where the variable stationary blade 5 is provided (dotted line), and reference numeral 12 denotes a case where the variable stationary blade 5 is not provided (solid line). Fluid 9 entering through fluid inlet nozzle 1a
The pressure is reduced on the bucket row 4 side, during which the work is performed and discharged downstream. Reference numeral 16 denotes a pressure difference at the exit of the moving blade 4 when the variable stationary blade 5 is provided and when the variable stationary blade 5 is not provided. The fluid 10a may be directly discharged as exhaust gas on the downstream side, or may be supplied to another plant to utilize back pressure.

FIG. 2 is a view taken in the direction of arrows AA in FIG. 1A and shows the magnitude of the turning component. In the drawing, reference numeral 13 denotes a swirl component of the fluid 10 at the outlet of the variable stationary blade 5 when the variable stationary blade 5 is provided, and 14 denotes a fluid 1 when the variable stationary blade 5 is not provided.
A turning component of 0 is shown.

Next, the operation of the embodiment will be described. When the turbine 1 is used at the design point, the flow 10 at the outlet of the moving blade row 4 has no swirl component, so that the two rows of variable vanes 6,
7 both face the axial direction. When the turbine 1 is used out of the design point, as shown in FIG.
The upstream variable stationary blades 6 are oriented in a direction corresponding to the swirl angle of the exit flow of the moving blade row 4, and the downstream variable stationary blades 7 are oriented in the axial direction. Therefore, the swirl component of the fluid 10 when exiting the bucket row 4 is turned in the axial direction and collected as pressure by the diffuser 8, so that the pressure difference between the inlet and outlet of the bucket row 4 can be increased. .

The present invention is not limited to the embodiment described above, and various changes can be made without departing from the gist of the present invention.

[0018]

As described above, in the turbine of the present invention, the diffuser at the outlet of the moving blade row is provided with two variable vane rows in which the set angle can be arbitrarily changed. The swirl component is reduced by bending in the direction, and the energy of the velocity of the fluid can be converted into the energy of the pressure in the diffuser, thereby achieving an effect of improving the turbine efficiency.

[Brief description of the drawings]

FIG. 1A is a partial sectional view of a turbine of the present invention, and FIG. 1B is a diagram showing a difference in pressure at a moving blade row outlet when a variable stator blade is provided and when a variable stator blade is not provided. It is.

FIG. 2 is a diagram showing the magnitude of a turning component in the AA arrow direction of FIG. 1 (A).

FIG. 3A is a development view of the turbine of the present invention,
(B) is a figure which shows the state in which the flow of the fluid was turned by the variable stationary blade.

FIG. 4 is a partial sectional view of a steam turbine disclosed in Japanese Patent Application Laid-Open No. 4-41907.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbine 1a Nozzle 2 Casing 3 Turbine rotor 4 Moving blade 5 Variable stationary blade 6 Upstream variable stationary blade 7 Downstream variable stationary blade 8 Diffuser 9,10,10a Fluid flow 15 Fluid turning area 16 Pressure difference

Claims (1)

[Claims] In a turbine in which an outlet flow of a moving blade row is an axial flow and a diffuser is connected to the moving blade row, two variable stator vane rows are provided near an outlet of the moving blade row. A turbine, wherein the swirling component of the flow is turned in the axial direction.