JPS6338605A - Speed governing stage structure for steam turbine - Google Patents

Abstract

PURPOSE:To prevent reduction of strength of moving blades and a rotor, by setting the distribution along the circumferential direction, of height of a set of stationary blades in the first stage nozzle box, as being long at the center part of the set of the stationary blades, and being shorter toward both end parts. CONSTITUTION:A steam intake pipe 1 is connected to a set 12 of stationary blades in the first stage nozzle box 4. Blocked parts 13 are formed at both end parts of each set 12 of the stationary blades, and the distribution along the circumferential direction, of height of the set 12 of the stationary blades, is set as being long at the center part of this set 12 of the stationary blades, and being shorter toward both end parts. As quantity of generated steam is restricted at both end parts of the steam ejecting area, reaction force and impact force which act on moving blades are reduced. In this way, reduction of strength of the moving blades and a rotor, caused by fatigue, can be prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application) The present invention relates to a speed regulating stage structure of a steam turbine, and in particular, the present invention relates to a speed regulating stage structure of a steam turbine. By reducing the excitation force generated by! The present invention relates to a regulating stage structure for a steam turbine in which the reliability of JJ blades and rotor is [1]L.

(Prior Art) The structure of the steam inflow section at the high pressure initial stage of a conventional steam turbine is generally as shown in FIG.

High-temperature, high-pressure steam 2 is fed from a steam generating membrane (! Introduced in Box 4.

The introduced steam 2 expands while changing the outflow direction at the first stage stationary blade 5 disposed downstream of the nozzle box 4, and then flows to the outer periphery of the turbine rotor 6. It collides with the installed rotor X7, imparts rotational energy to the turbine rotor 6, and flows to the downstream turbine stage.

FIG. 8 is a cross-sectional view of the stationary blade 5 disposed in the nozzle box 4 shown in FIG. 7, viewed from the steam inflow side in the direction of arrows 1--2.

During rated load operation of the bad air turbine, the steam 2 flows through all the steam chambers 9a, which are partitioned by the partition wall 8.
9b, 9c, and 9d, passes through the static W5, is injected from the entire circumference of the nozzle box 4, becomes a high-speed jet against the opposing rotor blade 7, and collides with it.

The height 1'' of the steam flow path of the conventional stator blades 5 was uniform regardless of the position d3 in the circumferential direction of the nozzle box 4, and the distance between the steam ejected from between each stator blade was also uniform.

However, during low-load operation, a partial feed system is generally adopted, and the amount of steam fed to the steam turbine is suppressed.
Steam 2 is introduced only into some steam chambers, for example, the steam chamber 9a. The introduced steam passes through stationary blades 5 provided on the downstream circumference of the steam chamber 9a, and collides with the opposing rotor blades 7.

At this time, the movable W7 disposed around the entire circumference of the turbine rotor 6
receives steam power only when it passes downstream of steam chamber 9a during one rotation, and receives steam power when it passes behind other steam chambers 9b, 9c, and 9d to which steam is not supplied. do not have. For this reason, the motor 'fA7 does not receive steam power continuously as it does during rated operation, but only intermittently receives alcohol horns within a certain range during one rotation of the turbine rotor.

FIG. 9 schematically shows the relationship between the state of the steam flow passing through the stationary blades and the steam force acting on the rotor blades at this time.

A steam flow 10 passing through the stator blades 5 disposed in the nozzle box 4 flows from the steam ejection area W to the opposing moving TA7 side. Here, at both ends of the steam ejection area W, the steam flow 10
Due to the pressure difference between the front and rear of the stationary blades, the steam is dispersed and flows outward, where there is no steam flow.

Therefore, Il! does not reach the steam jet t4W and is not affected by the dispersed steam flow! No steam force acts on IIm +-. On the other hand, steam jet i! I! Motion M l that entered W
-2 is acted upon by a dispersed steam flow 16 that is dispersed in a direction opposite to the rotational direction 11 of the rotor. Further, in addition to the original steam flow, a dispersed steam flow 17 that is divided in the same direction as the rotor rotational direction 11 is added to the dynamic ML7 passing through the steam ejection area W, and is ejected. In other words, steam jet i! ! Motion M entering w
A bad air force in the opposite direction to the rotating direction momentarily acts on l-2, and on the contrary, the movement m at the moment when it passes through the bad air spout area W.
A large steam force acts on L7 in the direction of rotation.

FIG. 10 shows changes in the steam force acting on the rotor blades when the first product passes through this steam ejection area W.

Immediately after entering the steam jet vAW, molecules 11. Since the steam flow 16 acts against the steam, a reaction force P acts in the opposite direction to the rotation direction, but at the next moment, the steam force P reaches a steady level and remains almost constant even though small fluctuations occur. . Furthermore, at the moment of passing through the steam ejection region W, the rotor blades are subjected to an impact force P1 in the rotational direction because the air flow 17 acts in the rotational direction.

According to the conventional speed regulating stage structure, the value of the reaction force P is generally about 30% of the steady level steam power P0,
In addition, the impact force P can reach approximately 50% of the steam])P□. In other words, the range of steam force that the first bullet receives when passing through the steam ejection area W may reach 1.8 times the steam force at a steady level.

Furthermore, when the turbine is operated at low load, the steady level steam power PIIl itself is larger than during rated operation, so the moving blades are affected and the excitation force is proportionally weaker.

(Problems to be Solved by the Invention) In this way, in the conventional speed-governing stage structure, when implementing the low load series 2 of the targon in the so-called partial feeding system, it is necessary to At the moment of entering the steam ejection area and at the moment of passing through it, it was subjected to a severe impact no.j due to the dispersed steam flow. Therefore, there is a high possibility of vibration damage to the blades and rotor, and
[The decline in the strength of the noku due to fatigue was a problem.

The present invention was devised to solve the above problems, and reduces the fatigue of moving blades and rotors by reducing the level of impact force that acts on the steam turbine during low-load operation. The purpose of the present invention is to provide a regulating stage structure for a steam turbine that prevents a decrease in strength, improves the reliability of the entire steam turbine, and is particularly suitable for high-performance, low-load operation employing a partial feed system.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a first
The stator blades arranged circumferentially in the stage nozzle box are divided into several groups of stator blades by partition walls, and a steam inlet pipe that supplies steam is connected to each stator blade group to reduce static N during low load operation. J3 has a speed regulating stage structure of a bad air turbine that adjusts the load by adjusting the amount of steam supplied to a group of stator blades. The directional height distribution is increased by increasing the height of the steam passage of the Shizuoka segment 1~ arranged in the central part of the above-mentioned stationary vane rJ, and increasing the height of the steam passage of the Shizuoka segment 1~ arranged at the center part of the above-mentioned stationary vane rJ. The main point is that the height of the passage was set small.

(For flT) According to the two-legged configuration, there is a distribution in the height of the steam passage of the stationary vane segment that forms the steam ejection area within each group, and the height distribution is large with 43 in the center. On the other hand, since it is formed to be smaller near the partition walls at both ends, the ejected steam m also has a distribution proportional to its height. Zunawa I5, steam generation ti'i is suppressed near both ends compared to the central part of the steam ejection area, so the steam disperses and flows outward on both sides of the bad air ejection area! There is little R. Therefore, when the rotor blade enters the steam ejection area and when it passes through the steam ejection area, the reaction force and impact force acting on the rotor blade are reduced (L(), and the increase in vibration of fIIrA can be suppressed.

Therefore, a decrease in the strength of the moving blades and rotor due to fatigue due to imaging is prevented, and the reliability of the steam turbine during low-load operation is improved.

(Example) Next, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention, in which stator blades 5 disposed in the nozzle box 4 are divided into four groups by a partition wall 8, and a steam chamber 9a is partitioned into the nozzle box 4.
, 9b, 9c, and 9d are formed, and a steam inlet pipe 1 is connected to each steam chamber. During low load operation,
Steam is supplied only to the steam chamber 9a. The steam outlet area W formed in the steam chamber 9a is composed of stationary vane segments 12 arranged in an arc shape. Each stator vane segment 1
The heights of the steam passages 1 and 2 form a distribution within each group. That is, it is set small in the region close to the partition g8, and set large in the central part of the arc. In FIG. 1, the double hatched area indicates the steam passage blockage 13. In the embodiment shown in FIG. 1, the steam passage closing portion 13 is provided on the radially outer side of each stationary vane segment 12, and the height H of the steam passage gradually decreases from the center portion toward both ends. It is configured to do so.

Incidentally, the circumferential range in which the steam passage blocking portion 13 is provided is as follows:
The rotor blade entry side and the rotor blade passing side are each set at an angle equal to or more than one pitch of blade tJ. If the closing portion 13 is provided at an angle of at least one pitch, the influence of the vapor being dispersed can be reduced.

Next, the stator vane segment 1 forming the steam passage blockage 13
The structure of No. 2 will be explained with reference to FIG. 2 J3 and FIG. 3.

FIG. 2 is a perspective view showing one stator vane segment 12 constituting a stator vane group formed in an arc shape. Figure 2(a)
is a static 4 segment located in the center of the static vane group, and the cross section is approximately! '' shape, and the heights hl of the steam passages 14 on both sides of the stationary blades 5 are equal.

On the other hand, FIG. 2(E)) shows a stator lI segment 1- arranged at both ends of the stator vane 5, and the height of the steam passage on one side of the stator vane 5 is h2. H2 on the usage side
It is formed with a smaller h. By welding or otherwise welding the welded grooves 15 of the stator blade segments 12 whose steam passage heights have been gradually reduced or increased in this way, the stator blades can be assembled as shown in FIG. The height of the steam passageway will be constructed so that it changes smoothly within the city.

Further, FIG. 3 is a sectional view showing a state in which the stationary blade 5 is attached to the nozzle box 4. A rotor blade 7 is arranged opposite to a stationary blade 5 which is connected to the periphery of the opening of the nozzle box 4 . The movement located at the cross-sectional position shown in the figure! The height of the steam passage of A5 is h
2, and this height h2 is smaller than the height hl of the steam passage of the stator TA5 disposed at the center of the stator blade group. This difference in height (hl-h2) becomes the closed portion 13.

According to the speed regulating stage structure having the above configuration, the height of the steam passage of the stator vane 5 gradually increases in the circumferential direction from the portion adjacent to the partition wall 8. Accordingly, when the dynamic muff 7 enters the steam ejection area W, the amount of steam that collides with the dynamic muff A7 gradually increases from O. Furthermore, when the rotor blade 7 passes through the steam ejection area W, the steam M is suppressed again. Therefore, the rotor blade 7 is in the steam ejection area W
Reaction force P n in the opposite direction to the rotational direction received when entering the
d3 and the impact force PU in the rotational direction received during passing are significantly reduced.

A demonstration example of the effect of reducing impact force, etc. will be explained with reference to the graph of FIG. 4. FIG. 4 does not show changes in the steam power acting on the rotor blades from the time the rotor blades enter the steam ejection region W until they pass through, when the speed regulating stage structure according to the present invention is applied. When compared with FIG. 10, which shows the change in steam power in the case of the conventional speed-governing stage structure, the reaction force P, which the rotor blades 7 receive in the opposite direction to the rotational direction when entering the steam ejection region W, is one of the three. Furthermore, the rotational impact force PIJ received when passing through the steam ejection area W disappears, and the excitation force on the rotor blade becomes a steady level steam force.

In this case, the width of change in steam power is reduced to about 55% of the width of change in the case of the conventional structure, and vibration of the rotor blades can be significantly suppressed.

In the following embodiment, J is installed at both ends of the steam ejection area.
3. Since the structure is adopted to suppress the steam ifl ejected, the reaction force or impact force received when the rotor blade enters or passes through the steam ejection region can be significantly reduced. Therefore,
In high-performance, low-load operation using the partial feed method, the vibration level of the rotor blades can be reduced and the reliability of the AM and rotor can be significantly improved.

Next, another embodiment will be described with reference to FIGS. 5 and 6.

First, in Figure 5, the height of the steam passage is hl.

This is a case where two types of stator vane segments h2 are arranged in series to form a stator blade group, and the stator blade segments with low height steam passages are arranged near both ends of the stator blade group.

In this case, only two types of stator blade segments are manufactured, and compared to the case where the height of the steam passage is changed smoothly as shown in Figure 1, there are fewer types of stator blade segments, simplifying manufacturing and reducing costs. Can be reduced.

FIG. 6 shows a case in which the steam passage closing portions 13 disposed at both ends of the stator vane segments 1 to 12 are provided inside each of the stator vane segments 1 to 12 in the radial direction. In this case as well, the same effects as in the embodiment shown in FIG. 1 can be obtained.

(Effects of the Invention) As described above, according to the regulating stage structure of the present invention, the height of the alcohol passage of the stator vane segment disposed at the center of the arc-shaped stator blade group is increased, while the height of the stator vane segment is increased. The height of the steam passages of the static components installed at both ends are set small, so it is quiet! X! I! The impact force acting on the rotor blade passing through both ends of the blade is significantly reduced. Therefore, fatigue and strength deterioration due to dynamic torque and rotor vibration are prevented, and the reliability of the steam turbine as a whole is improved. In particular, by adopting a partial feed system, the reliability of the steam turbine can be greatly improved when performing low lζ (one load operation).

[Brief explanation of drawings]

Figure 1 shows the fruit of the present invention 711! Fig. 2 is a perspective view illustrating the shape of the stator blade segment;
FIG. 3 is a plane view of II[-I[[arrow in FIG. Figures 5 and 6 show examples of ponds. 7 is a sectional view showing the structure of the hot air inlet of a conventional steam turbine, and FIG.
9 is a cross-sectional view showing the relationship between the state of the steam flow passing through the stationary blades and the steam force acting on the dynamic W, and FIG. 10 is a view of the conventional speed regulating stage. In the structure S V
t: is a graph showing moving steam power. DESCRIPTION OF SYMBOLS 1... Steam inlet pipe, 2... Steam, 3... Turbine casing, 4... Nozzle box, 5... Stationary blade,
6... Turbine rotor, 7... Moving blade, 8... Partition wall, 9, 9a, 9b, 9C, 9d-Nan 51
Fc, 10-; fl airflow, 11...rotation direction, 12.
...Stator blade segment, 13...Closed part, 14...Steam passage, 15...Welding amount tip, 16...Distributed steam flow, 17...Distributed steam flow, H...Static Steam passage height of blades, h, h, , h3... Height of steep air passage of stationary blades, W...
・Bad air ejection area, L, L, 13 degrees 4. L5. L,,L7
...Rotating blade position. Applicant's agent Hisaku Hatano 1 Figure 3 Figure 4 Figure 1 Town Gumeshii Ryo I Place;

Claims (1)

[Claims] 1. Stator blades arranged circumferentially in the first stage nozzle box of a steam turbine are divided into several groups of stator blades by a partition wall, and steam is supplied to each stator blade group. In the regulating stage structure of a steam turbine, the steam turbine is connected to the steam inlet pipe and adjusts the load by adjusting the amount of steam supplied to the stator blade group during low-load operation. The height distribution in the circumferential direction of the steam passage of the stator vane group is made such that the height of the steam passage of the stator vane segment disposed in the central part of the stator blade group is increased, and A speed regulating stage structure for a steam turbine, characterized in that the height of a steam passage of a stator vane segment is set small. 2. The regulating stage structure for a steam turbine according to claim 1, wherein the stationary blade group is composed of two types of stationary blade segments having different heights of steam passages. 3. The circumferential height distribution of the steam passage of the stator vane segment is:
2. The speed regulating stage structure of a steam turbine according to claim 1, wherein the speed regulating stage structure changes smoothly within the stationary blade group.