JPH11229817A - Main steam pipe cooling device of steam turbine and steam turbine power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to ensure the strength and prevent high temperature oxidization even for main steam of a high temperature by having extremely high cooling efficiency of the main steam pipe wall surfaces and uniform temperature distribution of the main steam pipe. SOLUTION: This cooling device is provided with a main steam pipe 1, a concentrically shaped sleeve 2, and a heat shield plate 3 on the inside of the joint portion (or a portion in that vicinity) of a casing 8 and the main steam pipe 1 of a steam turbine. Steam for cooling is turned around and sent in the gap between the heat shield plate 3 and the main steam pipe 1 inner walls so as to cool the main steam pipe 1 and the joint portion of the main steam pipe 1 and the casing 8. In this case, cooling steam turnaround means 14 that revolves the supplied cooling steam 5 is provided in a cooling steam introduction pipe 4 that supplies the cooling steam to the gap such that the cooling steam flows in double revolution through the gap between the heat shield plate 3 and the inner wall of the main steam pipe 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a main steam pipe cooling device for a steam turbine and a steam turbine power plant, and more particularly, to a sleeve and a heat shield provided concentrically with the main steam pipe inside the main steam pipe. The present invention relates to a main steam pipe cooling device and a steam turbine power plant which are formed so as to circulate cooling steam in a space between the heat shield plate and the inner wall of the main steam pipe while swirling to cool the main steam pipe. It is.

[0002]

2. Description of the Related Art A steam turbine in a thermal power plant generally employed in the related art generally has a main steam / reheat steam temperature of 538/500 to improve the thermal efficiency of the turbine.
From 566 ° C to 600/600 ° C, and even 63
It tends to rise to 0/630 ° C.

The main steam inlet for guiding the main steam to the turbine has a thermal stress due to a difference in linear expansion coefficient with an increase in the main steam temperature because the main steam pipe and the high-pressure casing are made of different materials. There are problems that occur. Therefore, in order to secure the strength of the joint between the main steam pipe and the high-pressure casing and to prevent high-temperature oxidation, it is common practice to cool the periphery of the joint with low-temperature steam.

FIG. 2 is a sectional view schematically showing a main steam pipe when the main steam temperature is 600 ° C.
(A) shows a schematic system of a steam turbine and a configuration of a main steam inlet. As a main configuration, reference numeral 1 denotes a main steam pipe, in which an inlet sleeve 2 and a heat shield plate 3 are provided concentrically with the main steam pipe.

[0005] In this configuration, cooling of the junction between the main steam pipe 1 and the high-pressure casing by the low-temperature steam is performed by the heat shield plate 3 and the main steam pipe 1.
The cooling steam 5 having a swirling component is circulated through the gap between the main steam pipe 1 and the main steam pipe 1 to prevent the temperature from rising.

[0006] Incidentally, a cooling device for a main steam pipe of a steam turbine of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-174.
No. 106 or JP-A-64-8506.

[0007]

[Problems to be Solved by the Invention] As mentioned above, the steam turbine in a thermal power plant will become more and more main steam /
The temperature of the reheated steam tends to increase, and the main steam inlet for guiding the high-temperature main steam to the turbine is generally formed by joining the main steam pipe 1 made of a different material to the high-pressure casing, so that the temperature rises. Cooling around the joint is performed in order to suppress the thermal stress generated from the difference in linear expansion coefficient due to the difference in the thermal expansion coefficient.However, this cooling is performed by introducing cooling steam into the gap between the heat shield plate and the main steam pipe. In this way, the temperature of the main steam pipe 1 is prevented from rising.

However, since the supplied cooling steam flows while diffusing in the gap, the swirling component is gradually lost, and at the same time, the flow velocity is reduced, and the cooling effect is reduced. And
Further, when the main steam temperature rises to 600 ° C. or higher, a sufficient cooling effect cannot be obtained with this cooling structure, and a main steam pipe cooling device of this kind having high cooling efficiency is desired.

The present invention has been made in view of the foregoing, and it is an object of the present invention to provide an extremely high cooling efficiency of the main steam pipe wall surface, a uniform temperature distribution of the main steam pipe, and high temperature main steam. Another object of the present invention is to provide a cooling device for a main steam pipe of a steam turbine of this type which can secure the strength of the main steam pipe and prevent high-temperature oxidation.

[0010]

That is, the present invention provides a sleeve and a sleeve concentrically with a main steam pipe inside a joint (or a vicinity thereof) between a casing of a steam turbine and a main steam pipe for supplying main steam. A heat shield plate is provided, and cooling steam is circulated and circulated in the gap between the heat shield plate and the inner wall of the main steam pipe to cool the main steam pipe and a joint portion between the main steam pipe and the casing. In the main steam pipe cooling device for a steam turbine, the cooling steam introducing pipe for supplying the cooling steam to the gap is provided with cooling steam swirling means for turning the supplied cooling steam, so that the heat shield plate and the inner wall of the main steam pipe are connected to each other. The cooling steam is circulated in the gap in a double swirl to achieve the intended purpose.

The present invention further includes a sleeve and a heat shield provided concentrically with the main steam pipe inside a joint portion of a casing of the steam turbine and a main steam pipe for supplying main steam or in a vicinity thereof. The steam for cooling is swirled and circulated through the gap between the heat shield plate and the inner wall of the main steam pipe to cool the main steam pipe and the joint between the main steam pipe and the casing. In the steam pipe cooling device, a cooling steam introduction pipe for supplying cooling steam to the gap is provided at a lower portion so that the cooling steam flows upward while circling, and the cooling steam introduction pipe is provided with a supply cooling steam. Cooling steam swirling means for swirling is provided, and the cooling steam rises while doubly swirling in the gap between the heat shield plate and the inner wall of the main steam pipe, merges with the high-temperature leak steam flowing into the gap, and is discharged to the outside. Sa It is obtained by forming to so that.

In this case, a turbulence promoter or a radiating fin for promoting heat radiation is provided on an inner wall surface of the main steam pipe around a joint between the main steam pipe and the casing. Further, the heat shield plate is formed in a laminated structure having a predetermined gap, and formed so that cooling steam flows through the gap between the laminated layers. Further, spiral guide fins are provided in the gap between the main steam pipe and the heat shield plate so as to form a plurality of steam flow passages, and different cooling steams are circulated through the respective flow passages, and cooling is performed. It is formed so that the flowing direction of the steam is alternately opposite.

Further, the present invention provides a steam turbine driven by main steam, a casing covering the turbine, a main steam pipe joined to the casing and through which main steam supplied to the turbine flows, A sleeve provided concentrically with the main steam pipe on a joint portion of the main steam pipe or on an inner peripheral side near the joint portion, and formed between an outer peripheral surface of the sleeve and an inner peripheral surface of the main steam pipe. An inlet pipe connected to the gap to be supplied and supplying a fluid having a lower temperature than the main steam supplied to the turbine to the gap, wherein the inlet pipe has a substantially circumferential shape around the main steam pipe. A spiral projection or a spiral groove is formed inside the gap and spirally formed therein.

A steam turbine driven by the main steam, a casing covering the turbine, a main steam pipe joined to the casing and through which main steam supplied to the turbine flows, the casing and the main steam pipe A sleeve provided concentrically with the main steam pipe on the inner peripheral side near the joining portion or the joining portion, and a heat shield plate provided concentrically with the main steam pipe on the outer peripheral side of the sleeve. An introduction pipe that is connected to a gap formed between the outer peripheral surface of the heat shield plate and the inner peripheral surface of the main steam pipe and supplies a fluid having a lower temperature than the main steam supplied to the turbine to the gap. In the steam turbine power plant provided, a projection or a fin is formed on at least one of the outer peripheral surface of the heat shield plate, the inner peripheral surface of the main steam pipe, or the inner peripheral surface of the casing. It is.

[0015] Further, a steam turbine driven by main steam, a casing covering the turbine, a main steam pipe joined to the casing and through which main steam supplied to the turbine flows, the casing and the main steam pipe A steam turbine power plant comprising: a main steam pipe and a sleeve provided concentrically on an inner peripheral side near the joint portion or the joint portion; and an outer peripheral surface of the sleeve and an inner peripheral surface of the main steam pipe. A plurality of injection holes that are formed on the inner peripheral surface side of the main steam pipe, and a cooling pipe that ejects a fluid having a lower temperature than the main steam supplied to the turbine from the injection hole. It is prepared for.

That is, in the cooling device for the main steam pipe formed as described above, the cooling steam introduction pipe for supplying the cooling steam is provided with cooling steam swirling means for turning the supplied cooling steam, and Since the cooling steam is formed so as to circulate in the gap with the inner wall of the main steam pipe while rotating twice, the cooling effect of the wall surface of the main steam pipe can be extremely enhanced.

That is, the effect of the double swirl is that a vortex is generated inside the boundary layer under certain conditions. Usually, such vortices are called Geltra vortices, and the flow in the boundary layer where the vortices occur is generated near the wall surface inside the turbulent boundary layer while the transition from laminar flow to turbulent flow becomes faster. Has the effect of also suppressing the generation of a layer that is inconvenient for heat transfer called a laminar bottom layer
The cooling effect of the wall surface can be made extremely high.

Further, by providing a plurality of cooling steam supply introduction pipes, for example, by straight pipes or curved pipes, near the junction of the main steam pipe, the surface area where the cooling steam contacts the main steam pipe (or casing) can be increased. , Which
It is possible to perform uniform and efficient cooling as a whole from the inside of the main steam pipe (or casing) to the surface as well as the surface inside the main steam pipe.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 shows a cross section of the cooling device for the main steam pipe. 1 is a main steam pipe, 2 is an inlet sleeve, 3 is a heat shield plate, and 4 is a cooling steam introduction pipe.

As compared with the conventional cooling device, the main structural feature is that an inlet pipe 4 for supplying cooling steam is provided at a main steam inlet portion constituted by an inlet sleeve 2, a heat shield plate 3 and a main steam pipe 1. That is, cooling steam swirling means is provided in the portion. That is, in the case of this embodiment, a swirler 14 made of a torsion plate is provided inside the introduction pipe 4 as the cooling steam swirling means.

With such a configuration, the cooling steam 5 circulates in the gap between the heat shield plate 3 and the main steam pipe 1 while circling twice, and the main steam pipe 1 is efficiently cooled from its inner wall surface. It is done. In this case, the length of the torsion plate needs to be one pitch or more in order to obtain a stable swirling flow.

Here, the effect of the double swirl will be described in more detail. Generally, the swirl flow is effective for cooling the outer peripheral side wall surface (the inner wall of the main steam pipe 1) between the gaps.
Under certain conditions, a vortex is generated inside the boundary layer. Usually, such a vortex is called a Geltra vortex, as described above, and the flow in the boundary layer where the vortex is generated is rapidly changed from laminar flow to turbulent flow, and the flow inside the turbulent boundary layer is increased. There is also an effect of suppressing the generation of a layer that is inconvenient to heat transfer called a laminar bottom layer generated near the wall surface, and the cooling effect on the wall surface can be extremely enhanced.

Therefore, supplying the cooling steam 5 while swirling it twice is effective for enhancing the cooling effect. However, if the same effect can be obtained by disturbing the flow, an obstacle or an orifice may be provided at the outlet of the cooling steam introduction pipe 4. FIG. 12 shows the difference between the conventional single swirl flow and the double swirl flow according to the present invention.

FIG. 3 shows another embodiment of the present invention.
In this case, cooling steam is supplied from a lower part of the main steam pipe to a gap formed between the heat shield plate 3 and the main steam pipe 1 and is circulated to an upper part side. That is, the supplied cooling steam 5 flows upward while cooling the main steam pipe, merges with the high-temperature leak steam flowing into the gap from the upstream side, and discharges it to the outside to prevent the temperature of the main steam pipe from rising. It was made.

FIG. 4 shows still another embodiment of the present invention, in which a turbulence promoter 11 for promoting heat radiation is provided inside the main steam pipe and the inside of the casing, particularly around the joint requiring cooling. It is. Thereby, a turbulent vortex is generated near the boundary layer on the wall surface, and a higher cooling effect can be obtained. Since the turbulence promoter 11 is intended to generate turbulent vortices, it may be provided on the surface of the heat shield plate 3 as shown in FIG. 14, for example.

FIG. 5 shows still another embodiment of the present invention. A cooling pipe 13 having an injection hole is provided in a gap between the heat shield plate 3 and the main steam pipe 1, and cooling is performed from the injection hole. Impingement cooling is performed in which cooling steam impinges on the inner wall of the main steam pipe.

FIG. 6 shows still another embodiment of the present invention, in which a spiral guide fin 6 having two passages is formed.
, The main steam pipe 1 is characterized by a counter-flow type in which the supply of cooling steam is separately provided, and the entire main steam pipe can be more effectively and uniformly cooled. In addition,
Continuous spiral guide fins 6 provided at equal intervals
The effect of (1) is that the flow passage area through which the cooling steam 5 passes is always constant, so that the diffusion of the flow can be prevented and a stable flow velocity can be secured. Therefore, the cooling steam 5 passing through the gap can obtain substantially the same heat transfer coefficient throughout the main steam pipe 1 and stabilizes the cooling effect.

FIG. 7 shows another embodiment of the present invention.
A nozzle type is provided by gradually reducing the inner diameter of the introduction pipe 4 for supplying the cooling steam, and the heat transfer characteristic is improved by increasing the outflow speed.

FIG. 8 shows another embodiment of the present invention.
That is, a plurality of heat radiation fins 7 for promoting the heat radiation effect are provided. As a result, the heat radiation area can be increased,
It is possible to obtain a higher cooling effect, which is also effective in reducing the amount of cooling steam. In this case, the shape of the radiation fins 7 is not particularly limited, and may be a continuous shape or an intermittent pin fin shape.

FIG. 9 shows another embodiment of the present invention.
As shown in FIG. 1, the cooling steam flows in the gap between the heat shield plate 3 and the main steam pipe 1 while the main steam flows in the gap between the main steam pipe 1 by forming the introduction pipe 4 for supplying the cooling steam also as a swirler. Allow tube to cool. As an example of this structure, the cross section of the introduction pipe 4 may be rectangular, and the rectangular pipe may be turned by twisting.

FIG. 10 shows another embodiment of the present invention, in which the heat shield plate 3 has a laminated structure at a main steam inlet portion constituted by an inlet sleeve 2, a heat shield plate 3 and a main steam pipe 1. By flowing the cooling steam between the layers, the main steam pipe is cooled, and at the same time, the amount of heat transferred to the main steam pipe is reduced, thereby increasing the cooling effect.

FIG. 11 shows another embodiment of the present invention. By providing a plurality of inlet pipes 4 for supplying cooling steam by straight pipes or curved pipes near the junction of the main steam pipes, the cooling steam 5 is formed. The surface area in contact with the main steam pipe 1 (or the casing 8) can be increased. This allows not only the inner surface of the main steam pipe but also the main steam pipe (or casing)
The entire periphery of the joint can be cooled from the inside to the surface.

As described above, in the cooling device for the main steam pipe formed as described above, the swirler 14 is provided in the inlet pipe 4 for supplying the cooling steam at the main steam inlet. Cooling steam 5 consists of heat shield plate 3 and main steam pipe 1
In the gap between the vortex and the whirlpool, the vortex flows in the boundary layer where the vortex is generated. It is possible to suppress the generation of a layer that is inconvenient for heat transfer called a laminar bottom layer generated near the wall surface inside the flow boundary layer, and to achieve extremely high and uniform cooling of the entire wall surface.

[0034]

As described above, according to the present invention, the cooling efficiency of the main steam pipe wall is extremely high, the temperature distribution of the main steam pipe becomes uniform, and the main steam pipe can be cooled even with high-temperature main steam. This type of cooling device for a steam turbine main steam pipe capable of ensuring the strength and preventing high-temperature oxidation can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a cooling device for a steam turbine main steam pipe of the present invention.

FIG. 2 is a sectional view showing a conventional cooling device for a steam turbine main steam pipe.

FIG. 3 is a sectional view showing another embodiment of the cooling device for the main steam pipe of the steam turbine of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the cooling device for the main steam pipe of the steam turbine of the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the cooling device of the steam turbine main steam pipe of the present invention.

FIG. 6 is a cross-sectional view showing another embodiment of the cooling device of the steam turbine main steam pipe of the present invention.

FIG. 7 is a sectional view showing another embodiment of the cooling device of the steam turbine main steam pipe of the present invention.

FIG. 8 is a sectional view showing another embodiment of the cooling device for the main steam pipe of the steam turbine of the present invention.

FIG. 9 is a cross-sectional view showing another embodiment of the cooling device of the steam turbine main steam pipe of the present invention.

FIG. 10 is a cross-sectional view showing another embodiment of the cooling device of the steam turbine main steam pipe of the present invention.

FIG. 11 is a cross-sectional view showing another embodiment of the cooling device for a steam turbine main steam pipe of the present invention.

FIG. 12 is a view showing a cooling steam flow state of the main steam pipe cooling device of the present invention.

FIG. 13 is a partially broken side view of a steam turbine system and a steam inlet.

FIG. 14 is a sectional view showing another embodiment of the cooling device for the main steam pipe of the steam turbine of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main steam pipe, 2 ... Inlet sleeve, 3 ... Heat shield plate, 4 ... Introduction pipe, 5 ... Cooling steam, 6 ... Guide fin, 7 ... Radiation fin, 8 ... Casing, 9 ... Seal ring, 10 ... Main steam , 11 ... turbulence promoter, 12 ... discharge pipe,
13 ... impingement cooling pipe, 14 ... swirler.

Continued on the front page (72) Inventor Takeshi Onoda 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (72) Inventor Tsuyoshi Takano 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Hitachi, Ltd.Hitachi Plant

Claims (8)

[Claims] 1. A sleeve and a heat shield plate concentrically with a main steam pipe are provided inside a joint portion of a casing of a steam turbine and a main steam pipe for supplying main steam or in a vicinity thereof. Main steam pipe cooling of a steam turbine, which circulates cooling steam while swirling through the gap between the main steam pipe and the inner wall of the main steam pipe to cool the main steam pipe and the joint between the main steam pipe and the casing. In the apparatus, a cooling steam introducing means for supplying cooling steam to the gap is provided with a cooling steam swirling means for swirling the supplied cooling steam, and the cooling steam is swirled twice in the gap between the heat shield plate and the inner wall of the main steam pipe. A main steam pipe cooling device for a steam turbine, wherein the cooling device is circulated while flowing. 2. A heat shield plate, comprising: a sleeve and a heat shield plate concentrically with the main steam pipe inside a joint portion of a casing of a steam turbine and a main steam pipe for supplying main steam or a portion in the vicinity thereof. Main steam pipe cooling of a steam turbine, which circulates cooling steam while swirling through the gap between the main steam pipe and the inner wall of the main steam pipe to cool the main steam pipe and the joint between the main steam pipe and the casing. In the apparatus, a cooling steam introduction pipe for supplying cooling steam to the gap is provided at a lower portion, and the cooling steam is formed to circulate upward while circling, and the cooling steam introduction pipe is swirled to supply cooling steam. Cooling steam swirling means is provided so that the cooling steam rises while double swirling in the gap between the heat shield plate and the inner wall of the main steam pipe, merges with the high-temperature leak steam flowing into the gap, and is discharged to the outside. Into shape Main steam pipe cooling system of the steam turbine, characterized in that the. 3. The main steam of a steam turbine according to claim 1, wherein a turbulence promoter or a radiating fin for promoting heat radiation is provided on an inner wall surface of the main steam pipe around a joint between the main steam pipe and the casing. Tube cooling device. 4. The steam turbine according to claim 1, wherein the heat shield plate is formed in a laminated structure having a predetermined gap, and formed so that cooling steam flows through the gap between the laminated layers. Main steam pipe cooling system. 5. A helical guide fin is provided in a gap between the main steam pipe and the heat shield so as to form a plurality of steam flow passages, and different cooling steam flows through each flow passage. 3. The main steam pipe cooling device for a steam turbine according to claim 1, wherein the cooling steam is formed so that a flowing direction of the cooling steam alternately becomes a counterflow. 6. A steam turbine driven by main steam, a casing covering the turbine, a main steam pipe joined to the casing and through which main steam supplied to the turbine flows, the casing and the main steam pipe. A sleeve provided concentrically with the main steam pipe on the inner peripheral side in the vicinity of the joint or the joint, and a gap formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the main steam pipe And a supply pipe connected to the main pipe and supplying a fluid having a lower temperature than the main steam supplied to the turbine to the gap, wherein the supply pipe is provided in a substantially circumferential direction of the main steam pipe. A steam turbine power plant connected to the gap and having a spiral projection or spiral groove formed therein. 7. A steam turbine driven by main steam, a casing covering the turbine, a main steam pipe joined to the casing and through which main steam supplied to the turbine flows, the casing and the main steam pipe A sleeve provided concentrically with the main steam pipe on the inner peripheral side near the joining portion or the joining portion, and a heat shield plate provided concentrically with the main steam pipe on the outer peripheral side of the sleeve. An introduction pipe that is connected to a gap formed between the outer peripheral surface of the heat shield plate and the inner peripheral surface of the main steam pipe and supplies a fluid having a lower temperature than the main steam supplied to the turbine to the gap. In the steam turbine power plant provided, a projection or a fin is formed on at least one of the outer peripheral surface of the heat shield plate, the inner peripheral surface of the main steam pipe, or the inner peripheral surface of the casing. Steam turbine power plant. 8. A steam turbine driven by main steam, a casing covering the turbine, a main steam pipe joined to the casing and through which main steam supplied to the turbine flows, the casing and the main steam pipe. A steam turbine power plant comprising: a main steam pipe and a sleeve provided concentrically on an inner peripheral side near the joint portion or the joint portion; and an outer peripheral surface of the sleeve and an inner peripheral surface of the main steam pipe. A plurality of injection holes that are formed on the inner peripheral surface side of the main steam pipe, and a cooling pipe that ejects a fluid having a lower temperature than the main steam supplied to the turbine from the injection hole. A steam turbine power plant comprising: