JPH06101410A - Nozzle for steam turbine - Google Patents

Abstract

PURPOSE:To improve turbine efficiency by providing a nozzle moving part which varies a flowing direction of steam while increasing and decreasing an outlet area of a nozzle according to an operation condition of a steam turbine, and optimumly controlling velocity and angle of the steam flowing according to a turbine load. CONSTITUTION:A nozzle moving part 2 is provided on a part of a nozzle 1 of a steam turbine 1. The nozzle moving part 2 is controlled by means of a control device 14 through a link mechanism 13 such that an outlet area of the nozzle 1 is decreased when a load of the steam turbine is small. A lower end of a rotary bar 15 fixed to the nozzle moving part 2 is pivoted to a lower side l6a of a cutout 16 on an upper portion of the outlet side of the nozzle 1, while an upper end is pierced through an outer ring 7 and pivoted to a partition plate, then fixed to one end of one of links 17 of the link mechanism 13. The other end of each link 17 is pivoted to one end of a link bar 18a. The other end of the link bar 18a is connected to a link bar 18b interlocked with a piston 19b of a hydraulic cylinder 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine nozzle (stator vane), and more particularly to a steam turbine nozzle suitable for use in the low pressure final paragraph and its vicinity.

[0002]

2. Description of the Related Art A nozzle (stator vane) of a steam turbine is a nozzle for aligning the outflow direction of the steam with a specific direction so that the steam efficiently flows into the blade when the steam heat energy is changed to velocity energy. Then it is one of the important components.

The operation of the nozzle will be described with reference to FIG. 5 by taking the case of high load as an example. When the nozzle 1 and the blade 2 have a relative relationship as shown in the figure, the steam flow at the nozzle outlet 3 and the peripheral speed of the blade Four
Then, it becomes like a relative flow 5 of steam to the blades. As a result, the relative flow 5 of steam to the blade 2 flows into the blade 2 at an optimum angle and velocity. In FIG. 6, the nozzle is seen from the cross-sectional direction, and the nozzle 1 is welded to the outer ring 7 and the inner ring 8. At high load, the steam indicated by the chain line arrow in the figure flows without causing turbulence.

[0004]

However, in the nozzle having the above-mentioned action, the nozzle 1 and the blades 2 are designed so that the steam can be sufficiently flowed at the maximum load, and there are the following problems.

First, in recent years, the capacity of steam turbines for power generation has been increasing in recent years, and blades of about 1 meter are used for the final stage blades. Also, due to the difference in power demand between day and night, The turbine is operated at maximum output, and at night, it is operated at low output. However, as described with reference to FIGS. 5 and 6, since the nozzle 1 and the blades 2 are designed so that sufficient steam can flow at the maximum load, the steam pressure and temperature are low at a low load, and the flow rate is small. Inevitably, the difference in enthalpy and pressure between the inlet and outlet of the nozzle 1 becomes small. Therefore, when the load is low, the steam flow 3 at the nozzle outlet becomes small as shown in FIG. 7, so that the relative flow 5 of the steam to the blades changes, and a separation flow 6 is generated, which deteriorates the performance of the blades. Especially in the final paragraph with long wings,
As shown in FIG. 7, the steam inflow angle into the blade near the tip of the blade largely deviates from the original design point, resulting in a problem that the performance is significantly reduced.

[0006] The other is a flow with no turbulence at the inlet and outlet of the blade 2 at high load as shown in Fig. 6, but at low load as shown in Fig. 8, the blade inlet and outlet near the root. Pressure difference reverses and the flow is greatly disturbed.
It is known to cause reflux as shown in. Such turbulence of the flow causes a loss and deteriorates the performance of the turbine, and also causes a large exciting force on the blades 2 and the nozzle 1. Therefore, it is necessary to consider the vibration in the design of the turbine.

In the prior art, performance deterioration is unavoidable, and the blades 2 and the nozzles 1 are strongly configured against vibrations, and the blades are connected to each other to have a vibration suppressing effect. There is a case in which a stationary blade was recently damaged at a certain nuclear power plant, because there was no choice but to take countermeasures, and sometimes large and unexpected vibration could occur. In addition, the operation under a low load is sometimes restricted, which is one of the major obstacles to the reliability and operation of the steam turbine.

[0008] Such a conventional problem is a machine in which a steam turbine is firmly assembled with a tough metal, and since the blades and nozzles have a constant shape, the steam that changes according to the load of the turbine. It was thought that the turbine could not follow and loss and vibration at low load could not be avoided to some extent.

As a similar means for solving the above problems,
For example, it is known to raise and lower the flap 10 of the main wing 11 of the aircraft 9 as shown in FIG. That is, FIG. 10 is a sectional view taken along the line AA of FIG.
Flap 1 at low speed for takeoff and landing, where 0 is the horizontal direction
Although the blade area is increased with 0 as the downward direction to increase the buoyancy, this does not control the state of the fluid at the outlet of the flow like the nozzle of the steam turbine, and the means shown in FIG. It is a technology.

Further, in the example of the movable blade of the fluid machine, there are guide vanes of the compressor, variable pitch blades of the pump, etc., but these are examples of driven machines, and such a structure is applied to the prime mover. No case has ever existed. Therefore, it is another technique based on another idea in terms of fluid dynamics, and even if it is used for these techniques, the above-mentioned problems cannot be solved.

Therefore, the present invention optimally controls the speed and angle of the steam flowing into the blades according to the turbine load to improve turbine efficiency, suppresses flow turbulence to reduce turbine loss, and vibrates. It aims at providing the nozzle of the steam turbine which suppresses.

[0012]

According to a first aspect of the present invention, a steam turbine nozzle is fixed to an outer ring and an inner ring for allowing steam to flow into a blade with the outflow direction aligned in a specific direction. A nozzle movable portion that changes the direction of vapor outflow by increasing or decreasing the outlet area of the nozzle according to the state is provided.

According to a second aspect of the present invention, there is provided control means for movably controlling the nozzle movable portion based on the steam turbine load signal or the pressure difference between the inlet and outlet of the nozzle.

[0014]

With the above structure, the angle of the steam flowing out of the nozzle is changed so that the nozzle outlet area is narrowed, the outflow speed of the steam is increased, and the angle of the steam flowing into the blade is almost equal to that at the time of high load, and peeling occurs. Is also suppressed and the efficiency of the turbine is improved. In addition, since the nozzle outlet pressure can be adjusted at the same time, the inlet pressure of the blade following the nozzle can be increased, the backflow phenomenon near the blade root is suppressed to reduce the loss, and the blade is excited by the turbulence of the flow. Vibration can be suppressed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view of a nozzle of a steam turbine showing a first embodiment of the present invention. The difference from the nozzle of the steam turbine described in FIGS. 5 to 8 is that the nozzle movable part 12 is operated in a part of the nozzle 1 so that the nozzle outlet area becomes narrow when the load of the steam turbine is small. The point is that the link mechanism unit 13 and the control device 14 are provided.

The nozzle movable portion 12 is provided in a cutout portion 16 on the upper side of the outlet of the nozzle 1, and a rotary rod 15 is fixed to the nozzle movable portion 12, and the lower end of the rotary rod 15 is a cutout portion 1.
The lower side 16a of the rotary shaft 6 is pivotally supported while the rotary rod 1
The upper end of 5 penetrates the outer ring 7, is pivotally supported by a partition plate (not shown), and is further fixed to one end of a link 17 of the link mechanism portion 13. On the other hand, the link mechanism unit 13 has a link 1
Link bar 18a pivotally supported on the other end of 7 and operating horizontally
Is provided, and an interlocking link rod 18b that branches from one end of the interlocking link rod 18a and interlocks with the piston 19a of the hydraulic cylinder 19 is provided. The control device 14 measures and sets the relationship between the turbine load signal and the hydraulic pressure so that the position of the nozzle moving part 12 is optimal according to the operating state of the steam turbine, for example, the turbine load signal. Further, the hydraulic pressure of the hydraulic cylinder 19 is changed based on the above relationship and the turbine load signal during operation to bring the piston 19a to the optimum position.

With the above construction, the piston 19a moves in the direction of the arrow in the figure in response to the hydraulic pressure from the control device 14, and the interlocking link rod 18b and the interlocking link rod 18a also move in the direction of the arrow in the figure correspondingly. In response to this, the rotary rod 15 fixed to the link 17 is rotated in the direction of the arrow in the drawing as a fulcrum.
As a result, the nozzle movable part 12 is controlled to the optimum angle.

FIG. 2 is a sectional view taken along the line BB of FIG. 1, in which the nozzle movable portion 12 is narrowed in the direction in which the nozzle outlet area is narrowed as shown in FIG. move. As a result, the relative flow of steam 5 to the blades 5
As shown in FIG. 3, the steam angle is almost the same as in the high load state shown in FIG. 5, and the separation flow 6 is also suppressed.

As described above, the nozzle 1 includes the nozzle movable part 1
2 is provided, the nozzle movable portion 12 is fixed to the rotating rod 15, and the rotating rod 15 can rotate about a fulcrum provided on the partition plate. Such a nozzle structure is installed in all the nozzles in this paragraph, and the rotary rods 15 of the nozzles are connected to each other by the link mechanism unit 13, one end of which is connected to the piston 19a of the hydraulic cylinder 19. There is. The hydraulic cylinder 19 is controlled by a turbine load signal, a pressure signal at a nozzle inlet, an outlet, a blade outlet, etc., and the nozzle movable part 12 is controlled at an optimum angle according to the operating state of the steam turbine.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the nozzle 1 and the nozzle movable part 12 are provided.
The first embodiment is the same as the first embodiment except that the bellows 20 is provided for rotating the nozzle movable part 12, and the connecting shaft 20a of the bellows 20 is attached to the rotary rod 15 via the link 17. Inside the bellows 20 is pressure piping 2
It is connected to the nozzle inlet of the paragraph via 1a. On the other hand, the outside of the bellows 20 is connected to the outlet side of the nozzle 1 or the outlet side of the blade 2 via a pressure pipe 21b. As a result, the connecting shaft 20a of the bellows 20 moves in the direction of the arrow in the figure according to the pressure difference between the inlet side of the nozzle 1 and the outlet side of the nozzle 1, and the angle of the nozzle movable part 12 is controlled by the rotation of the rotary rod 15. To be done. The bellows 20 as the driving unit may be composed of a diaphragm.

According to the second embodiment, since the angle of the nozzle movable portion 12 is controlled according to the pressure difference in the paragraph, the efficiency decrease and the vibration increase near the final stage of the steam turbine are eliminated.

As described above, the angle of the steam flowing out from the nozzle 1 is changed in the direction in which the nozzle outlet area is narrowed and the outflow speed of the steam is increased. Therefore, the angle of the steam flowing into the blade 2 is optimized even when the load is low. Peeling is also suppressed, and the efficiency of the turbine can be improved. Further, since the nozzle outlet pressure can be adjusted at the same time, the inlet pressure of the blade 2 following the nozzle 1 can be increased, the backflow phenomenon near the blade root portion can be suppressed to reduce the loss, and the turbulence of the flow excites the pump. It is possible to suppress the vibration of the blades.

[0025]

As described above, according to the present invention, the angle of the steam flowing out of the nozzle changes depending on the operating state of the steam turbine. It becomes almost equal and the peeling is suppressed and the efficiency of the turbine is improved. Also, since the nozzle outlet pressure is adjusted at the same time, the blade inlet pressure can be increased,
The backflow phenomenon near the blade root is suppressed to reduce the loss, and the vibration of the blade excited by the turbulence of the flow can be suppressed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a nozzle of a steam turbine showing a first embodiment of the present invention.

FIG. 2 is an explanatory view showing the operation of the nozzle of the steam turbine of FIG.

FIG. 3 is an explanatory diagram showing the flow velocity and angle of steam when the nozzle of the steam turbine of FIG. 1 has a low load.

FIG. 4 is an explanatory diagram showing a configuration of a nozzle of a steam turbine showing a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a flow velocity and an angle of steam at a high load in a nozzle of a conventional steam turbine.

FIG. 6 is an explanatory diagram showing a flow of steam at a high load in a nozzle of a conventional steam turbine.

FIG. 7 is an explanatory diagram corresponding to FIG. 5 showing the flow velocity and angle of steam at a low load in the nozzle of the conventional steam turbine.

FIG. 8 is an explanatory diagram corresponding to FIG. 6, showing a flow of steam at a low load in the nozzle of the conventional steam turbine.

FIG. 9 is an explanatory view showing a similar technique of a nozzle of a steam turbine.

10 is an explanatory view showing a cross section taken along the line AA of FIG. 9. FIG.

[Explanation of symbols]

 1 Nozzle 2 Blade 12 Nozzle Movable Part 13 Link Mechanism Part 14 Controller 15 Rotating Rod 16 Notch 17 Link 18a Interlocking Link Rod 18b Interlocking Link Rod 19 Hydraulic Cylinder 20 Bellows 21a Pressure Pipe 21b Pressure Pipe

Claims (2)

[Claims] 1. A nozzle of a steam turbine fixed to an outer ring and an inner ring for aligning the outflow direction of steam with a specific direction to flow into a blade, the outlet area of the nozzle being increased or decreased according to the operating state of the steam turbine. A nozzle for a steam turbine, comprising: a nozzle moving part that changes the outflow direction of the steam. 2. The nozzle of a steam turbine according to claim 1, further comprising control means for movably controlling the movable part of the nozzle based on a steam turbine load signal or a pressure difference between an inlet and an outlet of the nozzle. .