JP2000303802A - Steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure an operation without waste and which is stable operation even under an ultra-high temperature of steam by comprising a turbine rotor made of Fe group superalloy steel, austenitic alloy steel and the like, and a turbine blade made of a Ni-group superalloy steel, Co-group superalloy steel, austenite alloy steel and the like. SOLUTION: A steam turbine is formed by mounting a plurality of turbine stages 3, respectively formed by combining a turbine nozzle 1 and a turbine moving blade 2. The turbine moving blade 2 comprises a shroud 12 opposite to a packing ring 11 comprising a labyrinth 10 on its top, and its bottom is integrally buried in a turbine disc 13 formed with a turbine rotor 7. In this case, the turbine rotor 7 is made of a Fe group superalloy steel or austenitic alloy steel, the turbine moving blade 2 is made of Ni-group superalloy steel, Co-group superalloy steel or austenite alloy steel, and the packing ring 11 is made of austenite alloy steel. Whereby the leakage of steam caused by the difference in thermal elongation can be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steam turbine using a steam having a temperature of 650 ° C. or higher as a working fluid.

[0002]

2. Description of the Related Art Generally, it is said that the output and the thermal efficiency of a steam turbine can be increased by increasing the pressure and temperature of the steam flowing therein. For this reason, the steam turbine has a steam condition of 5.88 in the 1950s.
MPa, from 485 ° C. non-reheating to the second half of 1972 and after, pressure 24.12 MPa, temperature 538 ° C./566
The temperature was increased to one-stage reheating at ℃ and two-stage reheating at 538 ° C / 552 ° C / 566 ° C to increase the capacity of a single unit and improve the thermal efficiency.

Recently, in the case of single-stage reheating, the steam temperature 53
8 ° C./566° C. or 538 ° C./538° C. is almost fixed.

[0004] However, recently, as global warming phenomena, environmental destruction, and the like have been highlighted on a global scale, even in the field of thermal power plants, fuel consumption is further reduced to increase the capacity of a single unit. Research and development are being conducted, and one of the targets is to raise the steam temperature to 650 ° C or higher.

When the steam temperature is set to 650 ° C., there are still many problems to be solved. Although the strength of the turbine material has been assured, the steam turbine as a whole still has many problems. There are still unresolved issues, which are still under consideration.

[0006]

Conventionally, thermal power plants have used ferritic heat-resistant steel for turbine materials such as turbine rotors, turbine nozzles and turbine blades used in steam turbines. As a result, it becomes difficult to guarantee the strength. For this reason, for example, Japanese Patent Publication No. 60-31898,
JP-A-54385, JP-A-7-34202, JP-A-8-3697, etc. disclose heat-resistant steels improved to cope with this high temperature.

However, in a field where the temperature of the steam flowing into the steam turbine is so-called ultra-high temperature, that is, very high temperature of 650 ° C. or more, it is difficult to maintain sufficient strength guarantee even in the heat-resistant steel disclosed in the above-mentioned publication. It is said to be a thing.

Recently, austenitic alloy steels represented by Ni-based alloys have been applied to turbine materials such as turbine nozzles and turbine blades in order to cope with high temperatures.

However, austenitic alloy steels such as Ni-base alloys have a low thermal conductivity and a high coefficient of linear expansion, so that ferrite / martensite alloys used for packing rings for turbine casings and seals are used. Higher thermal elongation than steel. Therefore, in the steam turbine, the above-mentioned thermal expansion is added to the expansion due to the centrifugal force generated during operation, and the packing ring rubs (contacts) with the turbine rotor and the packing ring provided on the top of the turbine rotor blades. Rubbing of the turbine casing may occur.

In order to avoid the occurrence of the rubbing, it is conceivable to set a large clearance (gap) of the packing ring. However, if the clearance is made large, steam leaks, which leads to wasteful consumption of steam.

Further, when an austenitic alloy steel is used for a turbine nozzle or the like, thermal expansion occurs due to direct exposure to steam. It becomes stress. In order to suppress the generation of this thermal stress, it is conceivable to use a turbine material with a large coefficient of linear expansion for the turbine casing and to increase the thermal expansion of the turbine casing together with the turbine nozzle. Even so, the larger the diameter, the greater the thermal elongation, which rather causes a steam leak.

In the case of austenitic alloy steel, the production of large ingots is limited, which makes it difficult to produce large turbine parts such as bearings. For this reason, even when austenitic alloy steel is used for the turbine rotor, the bearing uses ferrite / martensite alloy steel.

However, when different materials are used, there is a possibility that galling occurs in the turbine rotor and the bearing.

As described above, in the steam turbine, many problems remain even if the austenitic alloy steel is used as the turbine material in accordance with the ultra-high temperature of the steam, and some new improvement measures are required. Was.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a steam turbine capable of performing a stable operation without waste even when the temperature of the steam is increased to an extremely high temperature.

[0016]

In order to achieve the above object, a steam turbine according to the present invention has an Fe-based superalloy steel, a Ni-based superalloy steel, and an austenitic alloy steel. A turbine rotor selected from any of the following, and a Ni-base superalloy steel, a Co-base superalloy steel, a turbine blade selected from any of the austenitic alloy steels,
And a packing ring made of austenitic alloy steel.

According to a second aspect of the present invention, there is provided a steam turbine according to the present invention.
a turbine rotor selected from e-base superalloy steel, Ni-base superalloy steel, and austenitic alloy steel;
A turbine rotor blade selected from one of a base superalloy steel, a Co base superalloy steel, and an austenitic alloy steel, a packing ring made of an austenitic alloy steel, and a turbine casing made of an austenitic alloy steel. It is provided.

In order to achieve the above object, a steam turbine according to the present invention, as described in claim 3, faces the top of a turbine rotor blade implanted in a turbine rotor and has a turbine casing. In a steam turbine having a packing ring to be engaged, the packing ring is divided into a plurality of pieces to form ring pieces, and a spring is interposed between the ring pieces.

In order to achieve the above object, the steam turbine according to the present invention is such that the packing ring is divided into six ring pieces.

According to a fifth aspect of the present invention, there is provided a steam turbine according to the present invention, wherein a meandering shape communicating with a ring piece accommodating chamber is provided in a turbine casing in which a packing ring is engaged. A passage is formed.

According to a sixth aspect of the present invention, there is provided a steam turbine according to the present invention.
a turbine rotor selected from e-base superalloy steel, Ni-base superalloy steel, and austenitic alloy steel;
It is provided with a turbine nozzle selected from any of a base superalloy steel, a Co base superalloy steel, and an austenitic alloy steel.

According to a seventh aspect of the present invention, there is provided a steam turbine in which a turbine stage in which a turbine nozzle and a turbine rotor blade are combined is divided into a plurality of stages along an axial direction. In a steam turbine provided with a turbine rotor provided and a bearing for supporting the turbine rotor, an overlay weld is formed on a journal portion of the turbine rotor supported on the bearing.

Further, in order to achieve the above object, in a steam turbine according to the present invention, the overlay weld is formed of a ferritic / martensitic alloy steel.

Further, in order to achieve the above object, a steam turbine according to the present invention has a turbine stage in which a turbine nozzle and a turbine blade are combined in a plurality of stages along an axial direction. In a steam turbine provided with a turbine rotor provided and a bearing that supports the turbine rotor, a sleeve is fitted to a journal portion of the turbine rotor that is supported by the bearing.

Further, in order to achieve the above object, a steam turbine according to the present invention has the following features.
The sleeve is made of ferritic / martensitic alloy steel.

Further, in order to achieve the above object, a steam turbine according to the present invention has the following features.
Temperature 650 in the steam turbine according to claim 1.
It uses steam of ℃ or more.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a steam turbine according to the present invention will be described below with reference to the drawings and reference numerals attached to the drawings.

FIG. 1 is a schematic sectional view of a steam turbine according to the present invention.

The steam turbine according to the present embodiment has a temperature of 6
This is an axial flow type in which steam having a temperature of 50 ° C. or higher is used, and a turbine stage 3 in which a turbine nozzle 1 and a turbine blade 2 are combined is arranged in a plurality of stages along the flow of the steam (main stream).

Further, the turbine nozzles 1 are arranged in a row along the circumferential direction, the head side is supported by a diaphragm outer ring 5 engaged with a turbine casing 4, and the bottom side is supported by a diaphragm inner ring 6. I do. The diaphragm inner ring 6 is provided with a packing ring 9 provided with a labyrinth 8 between the inner ring 6 of the diaphragm and a turbine rotor 7 to seal steam and prevent leakage.

On the other hand, the turbine blades 2 are arranged in a row along the circumferential direction while convectively flowing to the turbine nozzle 1.
A packing ring 11 having a labyrinth 10 on its top
Is provided with a shroud 12 whose bottom is planted and supported on a turbine disk 13 integrally formed with the turbine rotor 7.

Further, the turbine disk 13 uses the balance holes 14 to guide the leaked steam to the next paragraph, thereby cooling the next paragraph.

In the steam turbine having such a configuration, the turbine rotor material is selected from any of Fe-based superalloy steel, Ni-based superalloy steel, and austenitic alloy steel. The turbine blade material is Ni-base superalloy steel, C
One of o-based superalloy steel and austenitic alloy steel is selected. Further, an austenitic alloy steel is set as the packing ring material. The Fe-based superalloy steel of the turbine rotor material is specifically A286, and the Ni-based superalloy steel of the turbine blade material is specifically Nimon.
The austenitic alloy steel as the packing ring material is specifically SUS321.

Further, the steam turbine according to the present embodiment
As shown in FIG. 2A, the packing ring 11
A relatively wide space 4b is formed along the circumferential direction in the engagement groove 4a of the turbine casing 4 for housing
As shown in (b), the configuration is such that the thermal expansion of the packing ring 11 is allowed during operation. In this case, an austenitic alloy steel is selected as the turbine casing material.

FIG. 3 shows the linear expansion coefficient of ferrite / martensite alloy steel, specifically 12Cr forged steel, which has been conventionally used as a turbine nozzle material, a turbine blade material, a turbine rotor material, and a packing ring material. Nimonic 105 as a turbine nozzle material or a turbine blade material of a steam turbine according to the embodiment, A286 as a turbine rotor material, and SUS as a packing ring material
FIG. 321 is a diagram comparing the respective linear expansion coefficients of H.321 and 321.

In this diagram, the coefficient of linear expansion of the turbine rotor material and the turbine blade material applied to the present embodiment is about 50% or more larger than that of a conventionally used ferritic / martensitic alloy steel. Has become.

However, in this embodiment, austenitic stainless steel is used for the packing ring material, and the coefficient of linear expansion of the packing ring 9 is made larger than those of the turbine rotor blade 2 and the turbine rotor 7. Packing ring 11
Even if a material having a high linear expansion coefficient is selected, the heat directly received from the steam is less likely to be received than the turbine rotor blades 2 and the turbine rotor 7, so that the thermal expansion substantially increases in the turbine rotor blades 2 and the turbine rotor 7. It is lower than that.

Therefore, when comparing the thermal expansion of the packing ring 11 with the thermal expansion of the turbine rotor blades 2 and the turbine rotor 7, the difference is small.

As described above, in the present embodiment, the steam is 65
Even when the temperature reaches an extremely high temperature of 0 ° C. or more, the materials of the turbine components such as the turbine rotor blade 2, the turbine rotor 7, and the packing ring 9 are selected in consideration of the magnitude of the heat received from the steam. Since the difference based on thermal elongation is reduced to reduce steam leakage, it is possible to contribute to higher output and higher thermal efficiency based on ultra-high temperature of steam.

FIG. 4 is a schematic perspective view showing an embodiment of a packing ring applied to the steam turbine according to the present invention. In FIG. 4, (a) shows a state where the packing ring is stationary.
(B) has shown the state at the time of operation | movement of a packing ring, respectively. The same parts as those of the first embodiment are denoted by the same reference numerals.

The packing ring 11 according to the present embodiment comprises:
It is provided on the top of the turbine blade 2 and is divided into six ring pieces 15a and 15b along the circumferential direction thereof, and springs 16a and 16b are mounted between the ring pieces 15a and 15b. .

The packing ring 1 according to the present embodiment
As shown in FIG. 5, 1, the spring constants of the springs 16a and 16b mounted between the ring pieces 15a and 15b are set in consideration of the steam pressure difference. That is, when the ring pieces 15 a and 15 b facing the turbine blade 2 implanted in the turbine rotor 7 are engaged with the turbine casing 4, the meandering passage 1 is formed in the turbine casing 4.
7 and a ring piece storage chamber 18 are formed.

In the turbine casing 4 formed as described above, the ring-shaped housing 17 is formed from the meandering passage 17.
Is pressed on the head side of each of the ring pieces 15a and 15b. On the other hand, the steam leaking from the top of the turbine blade 2 presses the bottom of each of the ring pieces 15a and 15b. At this time, if a pressure difference occurs between the head side of each ring piece 15a, 15b and the bottom side of each ring piece 15a, 15b, it moves to each ring piece 15a, 15b and the turbine casing 4 side to generate steam. Leakage may increase or the ring pieces 15, a15b may move toward the turbine blade 2 to cause rubbing (contact).

The present embodiment takes this point into consideration, and empirically determines the steam pressure applied to the head side and the bottom side of each of the ring pieces 15a and 15b to match this pressure difference. The spring constants of the springs 16a and 16b are set as described above. In setting the spring constant, in addition to the above-described pressure difference, the respective coefficients of linear expansion of the turbine casing material, the packing ring material, and the turbine blade material are sufficiently considered.

As described above, in the present embodiment, the steam temperature 65
Each of the ring pieces 15a and 15b used at 0 ° C. or more is divided into six pieces, and springs 16a and 1
6b, and each ring piece 15a, 15b
The turbine casing 4 is engaged with the meandering passage 17.
And a relatively large ring piece storage chamber 18, while setting the spring constants of the springs 16a and 16b, the pressure difference of steam acting on the head side and the bottom side of each ring piece 15a and 15b and Since the coefficient of linear expansion of each component material has been sufficiently taken into consideration, each ring piece 15a, 15
b can be maintained at an appropriate position in accordance with the operation state, and the prevention of rubbing, combined with the prevention of low steam leakage, allows the steam turbine to operate stably.

FIG. 6 is a schematic cross-sectional view showing an embodiment of the steam turbine according to the present invention, which targets the respective materials of the turbine nozzle 1 and the turbine rotor 7.

In this embodiment, the turbine rotor material is F
e-base superalloy steel, Ni-base superalloy steel, or austenitic alloy steel, and any one of Ni-base superalloy steel, Co-base superalloy steel, and austenitic alloy steel as a turbine nozzle material. Is what you choose. A specific example of the Fe-based superalloy steel as the turbine rotor material is A286, and a specific example of the Ni-based alloy steel as the turbine nozzle material is Nimonic105.

Since the configuration of the steam turbine shown in FIG. 6 is the same as that shown in FIG. 1, the same reference numerals are given and the description thereof will be omitted.

As can be seen from FIG. 3, the coefficient of linear expansion of the turbine rotor material and the turbine casing material applied to this embodiment is about 50% as compared with that of the conventionally used ferritic / martensitic alloy steel. It is getting bigger.

However, in this embodiment, the turbine rotor material is made of Fe-based superalloy steel, and the linear expansion coefficient of the turbine rotor 7 is made larger than that of the turbine nozzle 1. Even if the turbine rotor 7 is selected to have a high linear expansion coefficient, heat received directly from steam is less likely to be received than the turbine nozzle 1, so that the thermal elongation is substantially lower than the turbine nozzle 1.

Therefore, the difference between the thermal expansion of the turbine nozzle 7 and the thermal expansion of the turbine rotor 7 is small.

As described above, in this embodiment, the steam is 65%.
Even when the temperature becomes extremely high, such as 0 ° C. or more, the materials of the turbine nozzle 1 and the turbine rotor 7 are selected in consideration of the magnitude of the heat received from the steam, and the difference based on the thermal elongation of each turbine component is reduced to reduce the steam. Because of the reduced leakage, it is possible to contribute to higher output and higher fuel efficiency based on the ultra-high temperature of the steam.

FIG. 7 is a partially cutaway schematic perspective view showing an embodiment of the steam turbine according to the present invention, which is intended for the journal portion of the turbine rotor 7. The same components as those of the first embodiment are denoted by the same reference numerals.

The steam turbine according to the present embodiment includes a turbine rotor 7 having a plurality of stages of turbine stages 3 in which a turbine nozzle 1 and a turbine blade 2 are combined, and a journal 19 of the turbine rotor 7 and a bearing 20. Is accommodated in the turbine casing 4.

The steam turbine according to the present embodiment
As shown in FIG. 8, an overlay (build-up) weld 21 is formed on the journal 19 of the turbine rotor 7.
The overlay weld 21 is formed of a ferrite / martensite alloy steel, for example, a CrMo low alloy steel on the Fe-based superalloy steel, specifically, the turbine rotor 7 made of A286. It is set.

In this embodiment, the turbine rotor 7
Although the overlay welding portion 21 is formed on the journal portion 19 of this embodiment, the present invention is not limited to this embodiment. For example, as shown in FIG.
A sleeve 22 made of the same material as the bearing 20, specifically, a ferritic / martensitic alloy steel may be fitted to the journal portion 19 of the turbine rotor 7. When fitting the sleeve 22 to the journal portion 19, after fitting the sleeve 22, which has been pre-baked and fitted, to the journal portion 19, a joint is connected to the end of the turbine rotor 7.

As described above, in this embodiment, one of the overlay welding portion 21 and the sleeve 22 is selectively provided on the journal portion 19 of the turbine rotor 7, and the journal portion 19 is formed of the same material as the bearing 20. Therefore, the occurrence of galling (galling) during operation can be prevented, and the steam turbine can be operated stably.

As described above, in the steam turbine according to the present invention, the materials of the turbine components are selected in consideration of the magnitude of the heat received from the steam, and the difference based on the thermal elongation of each turbine component is reduced. To reduce steam leaks,
This can contribute to higher output and higher thermal efficiency based on the ultra-high temperature of the steam.

Further, in the steam turbine according to the present invention, the journal portion of the turbine rotor is machined to the same material as the bearing to suppress galling generated during operation, so that the turbine components can be stably operated. it can.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a steam turbine according to the present invention.

FIG. 2 is a view showing an embodiment of the steam turbine according to the present invention, showing an engagement relationship between a packing ring and a turbine casing, wherein (a) shows an assembling state and (b) shows an operating state. .

FIG. 3 is a linear expansion coefficient diagram comparing the linear expansion coefficients of the materials of the respective components used in the steam turbine according to the present invention and the conventionally used materials.

FIG. 4 is a schematic front view showing an embodiment of a packing ring applied to the steam turbine according to the present invention, wherein (a) shows a state when the packing ring is stationary, and (b) shows a state when the packing ring is operating. Each is shown.

FIG. 5 is a schematic view showing a state where a packing ring applied to the steam turbine according to the present invention is incorporated in a turbine casing.

FIG. 6 is a schematic cross-sectional view showing an embodiment of a steam turbine according to the present invention, which targets materials of a turbine nozzle and a turbine casing.

FIG. 7 is a partially cutaway schematic perspective view showing an embodiment of a steam turbine according to the present invention, which is intended for a journal portion of a turbine rotor.

FIG. 8 is a partially enlarged schematic view of the journal section shown in FIG. 7;

FIG. 9 is a partially enlarged schematic view showing a modified example of the journal section shown in FIG. 7;

[Explanation of symbols]

 Reference Signs List 1 turbine nozzle 2 turbine rotor blade 3 turbine stage 4 turbine casing 4a engaging groove 4b space 5 diaphragm outer ring 6 diaphragm inner ring 7 turbine rotor 8,10 labyrinth 9,11 packing ring 12 shroud 13 turbine disk 14 balance hole 15a, 15b ring piece 16a, 16b Spring 17 Passage 18 Ring piece accommodation chamber 19 Journal part 20 Bearing 21 Overlay welded part 22 Sleeve

Claims (11)

[Claims] 1. A turbine rotor selected from any one of Fe-base superalloy steel, Ni-base superalloy steel, and austenitic alloy steel, and a turbine rotor selected from Ni-base superalloy steel, Co-base superalloy steel, and austenitic alloy steel. A steam turbine comprising: a turbine blade selected from any one of them; and a packing ring made of austenitic alloy steel. 2. A turbine rotor selected from any of Fe-base superalloy steel, Ni-base superalloy steel, and austenitic alloy steel, and a turbine rotor selected from Ni-base superalloy steel, Co-base superalloy steel, and austenitic alloy steel. A steam turbine comprising: a turbine blade selected from any one of them; a packing ring made of austenitic alloy steel; and a turbine casing made of austenitic alloy steel. 3. A steam turbine having a packing ring facing a top of a turbine rotor blade implanted in a turbine rotor and engaging with a turbine casing, the packing ring is divided into a plurality of pieces to form ring pieces. And a spring interposed between the ring pieces. 4. The steam turbine according to claim 3, wherein the packing ring is divided into six ring pieces. 5. The steam turbine according to claim 3, wherein a meandering passage communicating with the ring piece storage chamber is formed in the turbine casing with which the packing ring is engaged. 6. A turbine rotor selected from any of Fe-base superalloy steel, Ni-base superalloy steel, and austenitic alloy steel, and a turbine rotor selected from Ni-base superalloy steel, Co-base superalloy steel, and austenitic alloy steel. A steam turbine comprising: a turbine nozzle selected from any of the above. 7. A steam turbine provided with a turbine stage in which a turbine nozzle and a turbine rotor blade are combined in a plurality of stages along an axial direction, and a steam turbine provided with a bearing for supporting the turbine rotor. A steam turbine, wherein an overlay weld is formed on a journal of a turbine rotor that is supported. 8. The ferrite / martensite alloy steel for an overlay weld.
The steam turbine as described. 9. A steam turbine provided with a turbine stage in which a turbine nozzle and a turbine rotor blade are combined in a plurality of stages along an axial direction, and a steam turbine provided with a bearing for supporting the turbine rotor. A steam turbine, wherein a sleeve is fitted to a journal portion of a turbine rotor that is pivotally supported. 10. The steam turbine according to claim 9, wherein the sleeve is made of ferritic / martensitic alloy steel. 11. A steam turbine according to claim 1, wherein steam having a temperature of 650 ° C. or higher is used.