JPH1181908A - Steam turbine nozzle chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge an area of a nozzle chamber corresponding to an overload valve while holding mutual balance between an upper cabin and a lower cabin by forming gauging of a nozzle of a nozzle chamber corresponding to an overload valve larger than that of a pattern, and forming the nozzle chamber compact. SOLUTION: Arrangement of nozzles 31a of a nozzle chamber corresponding to an overload valve is compared with the arrangement of nozzles 31b of a pattern so as to visually and easily understand the arrangement. In the pattern, gauging λb as a ratio of throat width δb in relation to a nozzle pitch (t) is expressed with a formula λb =δb /(t). The nozzles 31a corresponding to the overload valve have the same nozzle pitch (t) with the pattern, and throat width δb of the nozzle is set larger than the ordinary valve so as to be δa >δb , gauging λa =δa /(t) is formed larger than that of the pattern. A desirable overload capacity can be obtained with the compact arrangement of a nozzle chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a nozzle chamber of a steam turbine.

[0002]

2. Description of the Related Art A conventional apparatus of this type will be described with reference to FIGS. 2 shows a partial cross-sectional shape of a very common steam turbine nozzle chamber, FIG. 3 schematically shows a main part of the steam turbine nozzle chamber, and FIG. 4 shows the amount of steam flowing into the nozzle chamber in FIG. And the relationship between pressure and
FIG. 5 shows a partial cross-sectional shape of another steam turbine nozzle chamber corresponding to FIG.

[0003] In order to improve the efficiency at a partial load, a steam turbine which performs nozzle cutoff speed control is provided with a plurality of steam control valves and a corresponding speed control stage nozzle chamber. The nozzle chamber is partitioned at every angle obtained by dividing the entire circumference of 360 ° by the number of steam control valves.

In general, it is planned that a rated load can be obtained by activating some of the plurality of steam control valves and the nozzle chambers corresponding to each of the plurality of steam control valves. An overload valve and a corresponding nozzle chamber are provided when the degree of vacuum in the condenser becomes low in summer or when it is necessary to temporarily overload due to a change in operating conditions. .

[0005] For example, when the number of steam control valves is four, three of them take a rated load, and the remaining one is used.
The role is divided and determined so that each of them becomes an overload valve.

FIG. 2 shows an example of the first steam control valve 1.
1, the second steam control valve 12, the third steam control valve 13, and the fourth
Among the steam control valves 14, first to third steam control valves 11 to 1
Three of the three correspond to the rated load, and the other one, the fourth steam control valve 14, is allocated as a so-called overload valve corresponding to the overload.

Therefore, corresponding to these valves, three nozzle chambers of a first steam control valve corresponding nozzle chamber 15, a second steam control valve corresponding nozzle chamber 16, and a third steam control valve corresponding nozzle chamber 17 are: 270 ° which is 3/4 of 360 ° of the entire circumference
The normal arrangement is such that the fourth steam control valve corresponding nozzle chamber 18 corresponding to the remaining one valve corresponding to the overload valve is allocated to the remaining 90 ° range,
This is preferable in terms of the overall arrangement including the cabin structure and the like.

[0008]

In the above-mentioned steam turbine, in order to improve the efficiency of the governing stage, the governing stage outlet pressure at the rated load is often designed to be high.

FIG. 3 schematically shows the steam turbine nozzle chamber, and FIG. 4 shows the relationship between the amount of steam flowing into the nozzle chamber and the pressure. Here, the forward pressure P ₁ of the main steam stop valve 21 and the steam control The pressure of the steam R reaching the nozzle chamber 23 via the valve 22 is represented by P
_2. Assuming that the outlet pressure of the governing stage moving blade 24 is P ₃ , the nozzle chamber pressure P ₂ obtained by subtracting the pressure loss of the main steam stop valve 21 and the steam control valve 22 from the forward pressure P ₁ of the main steam stop valve 21, steam amount G _R of the rated point by for differential pressure [Delta] P ₀ is decreased (the first to third steam control valve of the control stage outlet pressure P ₃ is compared with [Delta] P _R was determined in the same manner as the [Delta] P _0, ΔP ₀ ≪ΔP _R
The amount of steam flowing through the overload valve and the corresponding nozzle chamber does not become too large.

Therefore, in order to secure the flow rate of the overload valve, it is necessary to increase the area of the corresponding nozzle chamber, that is, the area of the fourth steam control valve corresponding nozzle chamber 18 shown in FIG.

From this, for example, as shown in FIG. 5, three valves corresponding to the rated load, ie, three valves corresponding to the first steam control valve 11, the second steam control valve 12, and the third steam control valve 13, Nozzle chambers, that is, the first steam control valve corresponding nozzle chamber 15 and the second steam control valve corresponding nozzle chamber 1
The arrangement range of the sixth and third steam control valve corresponding nozzle chambers 17 is 240 °, and the arrangement of the fourth steam control valve corresponding nozzle chamber 18 corresponding to the fourth steam control valve 14 corresponding to the overload valve is 120 °. There has been proposed an extension that extends over a wide range of applications.

However, since the turbine case is divided into the upper case 1 and the corresponding lower case,
In view of the fact that it is structurally desirable to equally divide two valves into two valves in the passenger compartment and two valves in the passenger compartment, the arrangement in FIG. 5 is spatially unbalanced, There is naturally a limit to the expansion range of the controllable valve corresponding nozzle chamber 18.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a nozzle which can expand an area of a nozzle chamber corresponding to an overload valve while maintaining a mutual balance between an upper vehicle compartment and a lower vehicle compartment.

[0014]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the gage of the nozzle of the nozzle chamber corresponding to the overload valve is made larger than that of the original type. The present invention provides a steam turbine nozzle chamber in which a nozzle chamber corresponding to (1) is compactly configured.

That is, in the nozzle chamber corresponding to the overload valve, the nozzle chamber is arranged by increasing the gauging of the nozzle corresponding to the ratio of the nozzle throat width to the nozzle pitch determined by the arrangement of the vanes constituting the nozzle. The nozzle area is increased without increasing the area of the overload valve, and the flow rate required by the overload valve is ensured while maintaining a compact shape as a whole.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The outer and inner compartments, which can be divided into upper and lower compartments, and the nozzle compartment formed at the center thereof, and this nozzle compartment is divided into one corresponding to the rated load and one corresponding to the overload. Since the overall basic structure described above is the same as that of the conventional structure, the description of the conventional structure will be referred to for the same basic structure, and redundant description will be omitted.

In FIG. 1, this is represented by (a)
And (b), and (a) shows the arrangement of nozzles in the nozzle chamber corresponding to the overload valve, which is the configuration of the main points in the present embodiment, and visually shows the characteristics of (a). As can be easily understood, (b) shows the nozzle arrangement of the prototype in comparison.

That is, in the prototype shown in FIG. _4B , gauging λ _b, which is the ratio of throat width δ _b to nozzle pitch t, is expressed by λ _b = δ _b / t. FIG. 4
In the case of (b), the throat width δ _b is a normal value, and therefore the gauging λ _b is a normal value.

On the other hand, in the embodiment shown in FIG. 4A, the nozzle pitch t is the same as that of the prototype, and
The throat width [delta] _a of the nozzle is made larger than the normal value, δ _a> δ _b
Therefore, gauging, λ _a = δ _a / t, is configured to be larger than that of the prototype.

That is, according to the present embodiment, since the steam passage area of the nozzle chamber corresponding to the overload valve is large, the amount of steam flowing into the turbine at the time of overload is reduced even if the nozzle chamber is arranged normally. It can be secured enough.

For this reason, the nozzle chamber corresponding to the overload valve, that is, the nozzle chamber 18 corresponding to the fourth steam control valve may be allocated to a range of 90 ° corresponding to １ ／ of the entire circumference, similarly to the conventional one. As a result, a desired overload capacity can be obtained with a compact and reasonable arrangement and arrangement of the nozzle chambers, and the reliability and economy of the steam turbine are further improved.

Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to such an embodiment.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0023]

As described above, according to the present invention, in the steam turbine nozzle chamber, the gauging of the nozzle of the nozzle chamber corresponding to the overload valve is made larger than that of the original type, thereby making the nozzle chamber corresponding to the overload valve compact. In the nozzle chamber corresponding to the overload valve in this way, by increasing the gauging of the nozzle corresponding to the ratio of the nozzle throat width to the nozzle pitch determined by the arrangement of the vanes constituting the nozzle, the nozzle chamber The nozzle area is expanded without expanding the area where the overload valve is arranged, and the flow rate required by the overload valve can be secured while maintaining the compact shape as a whole. To achieve the desired overload capacity, greatly improving the reliability and economy of steam turbines Those that could Rukoto.

[Brief description of the drawings]

FIG. 1 shows an arrangement of nozzles in a nozzle chamber corresponding to an overload valve according to an embodiment of the present invention in comparison with a nozzle arrangement of a prototype, (a) is an embodiment of the present invention, and (b) is a prototype. FIG. (A) shows the arrangement of the nozzles in the nozzle chamber corresponding to the overload valve, which is the configuration of the main points in the present embodiment, so that the characteristics of (a) can be visually and easily understood. FIG. 2B is a cross-sectional view showing the main part of the horizontal heat exchanger, which shows the nozzle arrangement of the prototype in comparison, from the front of the boiler.

FIG. 2 is an explanatory view showing a partial cross-sectional shape of a conventional general steam turbine nozzle chamber.

FIG. 3 is an explanatory view schematically showing a main part of a conventional steam turbine nozzle chamber.

FIG. 4 is an explanatory diagram showing the relationship between the amount of steam flowing into the nozzle chamber and the pressure in FIG. 3;

FIG. 5 is an explanatory diagram showing a partial cross-sectional shape of another conventional steam turbine nozzle chamber.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 outer casing 2 inner casing 3 nozzle chamber 11 first steam control valve 12 second steam control valve 13 third steam control valve 14 fourth steam control valve 15 nozzle chamber corresponding to first steam control valve 16 second steam control valve nozzle chamber 17 third steam control valve corresponding nozzle chamber 18 fourth steam control valve corresponding nozzle chamber 21 main steam stop valve 22 steam control valve 23 nozzle chamber P ₁ main steam stop valve before the pressure P ₂ nozzle chamber pressure P ₃ control stage outlet pressure δ _a, δ _b nozzle throat width t nozzle pitch λ _a, λ _b nozzles gauging

Claims (1)

[Claims] 1. A steam turbine nozzle chamber characterized in that the nozzle chamber of the nozzle chamber corresponding to the overload valve is made compact by making the gauging of the nozzle of the nozzle chamber corresponding to the overload valve larger than that of the original type.