JP4909113B2 - Steam turbine casing structure - Google Patents

Description

  The present invention relates to a steam turbine casing structure applied to marine and land reheat turbines, and more particularly, to a steam turbine casing structure with an improved intermediate-stage thermal shield.

Conventionally, steam turbines widely used for marine and land use (power plants, etc.) are used to generate propulsive power and power by blowing high-temperature steam generated externally onto the turbine (impeller) and rotating it. It is a combustion engine. Among such steam turbines, there is a reheat turbine in which thermal efficiency is improved by taking out and heating steam that expands in the turbine.

FIG. 6 is a cross-sectional view of the main part showing the vicinity of the intermediate pressure stage of the reheat turbine as a conventional steam turbine casing structure.
The illustrated steam turbine 10 is a reheat turbine in which a rotor 12 disposed inside an outer casing 11 rotates upon receiving supply of steam. A plurality of intermediate pressure blades 13 are attached to the intermediate pressure stage of the rotor 12. A plurality of intermediate-pressure stage stationary blades 14 are alternately attached to the intermediate-pressure stage moving blades 13 in the axial direction inside the intermediate pressure stage of the outer casing 11. Accordingly, the reheated steam supplied from the intermediate pressure steam inlet 15 into the passenger compartment flows between the intermediate pressure stage moving blade 13 and the intermediate pressure stage stationary blade 14 (see arrow S in the figure), so that the coaxial high pressure is supplied. A rotational force can be generated in the rotor 12 in cooperation with a stage (not shown) or the like.

In the steam turbine 10 described above, a thermal shield (partition member) 16 is provided to prevent the high-temperature reheat steam introduced into the intermediate pressure steam inlet 15 from coming into direct contact with the inner surface of the outer casing 11, thereby providing intermediate pressure steam. The inside of the inlet 15 is divided. In addition, the code | symbol 17 in a figure is a blade ring which supports the intermediate pressure stage stationary blade 14, and becomes a partition plate provided between each stage of the intermediate pressure stage stationary blade 14. FIG.
As a similar technique of the thermal shield 16 described above, by providing a thermal shield plate so as to form a gap along the outer peripheral surface of the inner casing, the thermal stress of the inner casing can be reduced by reducing the thermal stress of the inner casing. Some have suppressed thermal stress. (For example, see Patent Document 1)
Japanese Utility Model Publication No. 2-48642 (see FIGS. 1 and 2)

  By the way, in the steam turbine casing structure of the reheat turbine described above, in order to increase the efficiency by effectively using the steam, an intermediate pressure turbine using the reheat steam is added, and the steam to be used is also high in temperature. High pressure. For this reason, the steam turbine casing structure tends to increase in size in the axial direction, but in particular, marine steam turbines that are restricted in installation space are strongly required to be compact in the axial direction of the turbine.

However, in the steam turbine casing structure shown in FIG. 6, the blade ring 17 serving as the intermediate pressure side first and second stage partitioning members is fitted in a state of being directly embedded in the thickness of the outer casing 11. The inner wall surface of the outer casing 11 is exposed to the high-temperature reheat steam through the partition member 17. For this reason, in the conventional steam turbine casing structure, it is easily affected by the heat of the reheated steam. Therefore, a temperature gradient is generated in the turbine axis direction of the outer casing 11, and the casing is likely to be deformed causing steam leakage. It has a structure.
In addition, it is pointed out that the conventional steam turbine casing structure uses a thermal shield 16 that is separate from the blade ring 17, so that the number of parts is large and maintenance is difficult.

From such a background, it is desired to develop a steam turbine casing structure that can reduce the temperature gradient generated in the turbine axial direction of the outer casing and that facilitates maintenance by reducing the number of components.
The present invention has been made in view of the above circumstances, and the object of the present invention is to provide a steam turbine casing structure capable of reducing a temperature gradient generated in the turbine axial direction of the outer casing and reducing the number of parts. Is to provide.

In order to solve the above problems, the present invention employs the following means.
The steam turbine structure according to the present invention has a steam turbine casing in which a steam inlet for introducing steam supplied to the turbine section into the passenger compartment is divided by a partition member that blocks contact between the steam and the vehicle interior wall surface. In the structure, the steam inlet portion is divided by a blade ring-integrated partition member in which a blade ring supporting at least one stage of stationary blades from the upstream side of the turbine portion and the partition member are integrated, and the blade A convex portion of the wall surface of the vehicle interior is fitted to the ring-integrated partition member, and high-pressure stage exhaust steam is introduced as cooling steam into a divided space formed between the blade ring-integrated partition member and the cooling steam. Is provided with a steam flow path that passes through the divided space and is supplied to the downstream stage of the turbine section .

According to such a steam turbine casing structure, the steam inlet portion for introducing the steam supplied to the turbine section into the casing is a blade ring supporting at least one stage of the stationary blade from the upstream side of the turbine section. It is divided by a blade ring-integrated partition member that is integrated with the partition member, and has a structure in which a convex portion of the wall surface of the vehicle interior is fitted to the blade ring-integrated partition member, so that the upstream side of the turbine section with high steam temperature Then, the blade ring-integrated partition member is used in at least the first stage. For this reason, in addition to the reduction in the number of parts due to the integration of the parts, the blade ring-integrated partition member is fitted to the convex part of the vehicle interior wall surface on the upstream side of the turbine part having a high steam temperature. High-temperature steam is not in direct contact with the wall, making it less susceptible to thermal effects.
The stationary blade supported by the blade ring-integrated partition member may be only the first stage on the upstream side in the flow direction of the high-temperature steam, or may be from the first stage to a plurality of stages, and is particularly limited. It is not a thing.

In the present invention described above, it is preferable to introduce cooling steam into a divided space formed between the blade ring-integrated partition member and the vehicle interior wall surface. The thermal influence received from the steam can be further reduced.
In this case, it is preferable to use the cooling steam as high-pressure stage exhaust steam and merge it with the turbine section after passing through the divided space, so that the steam supplied to the steam turbine can be effectively used. In addition, what is necessary is just to join the cooling steam introduce | transduced into division space to a turbine part through one of the flow paths shown below.
(1) A flow path that penetrates the partition member portion of the blade ring-integrated partition member (2) A flow path that penetrates the blade ring portion of the blade ring-integrated partition member (3) A flow path that penetrates the convex portion of the vehicle compartment ( 4) Combination of (1) to (3) above
In particular, by providing a steam flow path as in (2) or (3), at least a part of the cooling air that has passed through the divided space is in the downstream stage of the turbine section where the temperature of the reheat temperature steam has decreased. Since the cooling air that is cooler than the reheated air joins, the temperature drop of the reheated steam that flows through the turbine section can be reduced.

According to the present invention described above, since the blade ring-integrated partition member is used at least in the first stage close to the steam inlet, on the upstream side of the steam inlet portion and the turbine portion where the steam temperature is high, Since steam does not come into direct contact, it is less susceptible to heat. For this reason, it is possible to prevent or suppress the occurrence of thermal stress and deformation acting on the passenger compartment, avoiding the local high temperature of the passenger compartment and excessive temperature gradient in the axial direction, A significant effect that steam leakage can be prevented is obtained.
In addition, since the number of parts is reduced by integrating the blade ring and the partition member, parts management and maintenance inspection are facilitated.

Hereinafter, an embodiment of a steam turbine casing structure according to the present invention will be described with reference to the drawings.
FIG. 2 is a cross-sectional view showing a schematic configuration of a high and intermediate pressure stage of a reheat turbine (steam turbine) as an example of a steam turbine casing structure. The illustrated steam turbine 20 is accommodated in an outer casing 21 in a state in which a rotor 22 integrated with a high and medium pressure stage is rotatably supported.
The outer casing 21 includes a main steam inlet 23 that introduces main steam, a main steam outlet 24 from which main steam that has passed through the high-pressure stage on the left side of the page from the main steam inlet 23, and reheat steam that introduces reheat steam. An inlet 25 and a reheat steam outlet 26 through which the reheat steam that has passed through the intermediate pressure stage on the right side of the paper surface from the reheat steam inlet 25 flow out are provided.

As shown in FIG. 1, the intermediate pressure stage moving blades 26 and the intermediate pressure stage stationary blades 27 are alternately arranged in the axial direction on the intermediate pressure stage side of the rotor 22 to form an intermediate pressure stage turbine section.
The intermediate pressure stage moving blade 26 is fixedly attached to the rotor 22. The intermediate pressure stage stationary blade 27 is fixedly attached to the inner wall surface of the outer casing 21 and a blade ring integrated partition member 30 described later, and a portion to which the intermediate pressure stage stationary blade 27 is attached is called a blade ring.

  A space serving as a steam inlet portion 28 communicating with the reheat steam inlet 25 is formed on the upstream side of the turbine portion. The steam inlet portion 28 is a ring-shaped space formed on the outer periphery of the rotor 12. That is, the steam inlet portion 28 is a space formed between the outer peripheral surface of the rotor 22 and the inner peripheral surface of the blade ring-integrated partition member 30, and the blade ring-integrated partition member 30 is located inside the outer casing 21. The annular member is disposed between the peripheral surface and the outer peripheral surface of the rotor 22.

  The blade ring-integrated partition member 30 includes a blade ring portion 31 that supports at least one intermediate pressure stage stationary blade 27 positioned upstream of the turbine portion, and a partition member 32 that forms an outer peripheral surface of a space serving as the steam inlet portion 28. Is an integrated member. In the illustrated configuration example, the blade ring portion 31 supports the intermediate pressure stage stationary blade 27 for the first stage and the second stage on the upstream side close to the steam inlet portion 28, but the present invention is not limited to this. Absent.

A divided space 29 formed between the partition member 32 of the blade ring integrated partition member 30 and the inner peripheral surface of the outer casing 21 is formed on the outer peripheral side of the steam inlet portion 28. That is, the divided space 29 is a space on the outer peripheral side formed by dividing the radial direction of the space formed between the inner peripheral surface of the outer casing 21 and the outer peripheral surface of the rotor 22 by the partition member 32.
The blade ring-integrated partition member 30 is attached by fitting a convex portion 21 a provided on the inner wall surface of the outer casing 21 to a concave portion 33 on the outer peripheral surface. That is, the blade ring-integrated partition member 30 is attached with a relatively small contact area by forming a gap with the inner wall surface of the outer casing 21.

According to the turbine casing structure configured as described above, the high-temperature reheat steam introduced from the reheat steam inlet 25 to the steam inlet portion 28 is, as indicated by an arrow S in the drawing, an intermediate pressure stage moving blade. The rotor 22 is caused to generate a rotational force when flowing through the turbine section constituted by the intermediate pressure stage 26 and the intermediate pressure stage stationary vane 27. At this time, since the temperature of the high-temperature reheated steam decreases as it flows through the turbine portion to the downstream side, the steam inlet portion 28 has the highest temperature.
However, the hottest reheat steam contacts the inner peripheral surface of the blade ring-integrated partition member 30, and this blade ring-integrated partition member 30 is substantially only at the convex portion 21 a fitted into the concave portion 33. It is in contact with the outer compartment 21. For this reason, the high-temperature reheat steam does not directly contact the outer casing 21, and the contact area between the outer casing 21 and the blade ring-integrated partition member 30 is kept relatively small only by the fitting portion of the uneven portion. Therefore, it is possible to suppress a temperature rise caused by heat transfer from the high-temperature reheated steam to the outer casing 21.

Accordingly, in the outer casing 21, an excessive temperature gradient is not generated in the turbine axis direction, that is, the formation of the temperature gradient in the turbine axis direction is suppressed, so that the thermal stress acting on the outer casing 21 is reduced and the vehicle is reduced. Chamber deformation can be prevented or suppressed. In other words, in the steam turbine 20, it is possible to prevent a local high temperature portion from being formed in the outer casing 21, and to avoid an excessive temperature gradient in the turbine axial direction. Efficient operation can be maintained by preventing steam leakage in the chamber 21.
In addition, since the blade ring part 31 and the partition member 32, which have conventionally been a plurality of parts, are integrated by adopting the blade ring integrated partition member 30, parts management and maintenance work can be facilitated by reducing the number of parts. Become.

Next, another embodiment of the above-described steam turbine casing structure will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part similar to embodiment mentioned above, and the detailed description is abbreviate | omitted.
In this embodiment, the cooling steam is introduced into the divided space 29 as indicated by an arrow Sc in the drawing. The cooling steam can be used as long as it has a temperature lower than that of the reheat steam, but in particular, a high-pressure stage exhaust steam having a temperature moderately lower than that of the reheat steam is suitable. By way of example, the temperature of the reheat steam and the cooling steam is shown as follows. The reheat steam temperature at the reheat steam inlet 25 is about 500 ° C., and the exhaust steam temperature of the high-pressure stage that becomes the cooling steam is about 350 ° C. to 400 ° C. It becomes.

When such cooling steam is introduced into the divided space 29, the thermal effect of the reheat steam on the outer casing 21 is further reduced. That is, since the outer casing 21 is cooled by introducing cooling steam at a temperature lower than the reheated steam into the divided space 29, the thermal stress acting on the outer casing 21 is further reduced, and thermal deformation can be suppressed. .
By the way, since the cooling steam described above effectively uses the steam, it cools the divided space 29 and then merges with the reheated steam and is supplied to the turbine section. Accordingly, if the temperature of the cooling steam is set low, the cooling capacity of the outer casing 21 is increased, but the temperature of the reheat steam is lowered and the operation efficiency of the steam turbine 20 is lowered. For the stage, it is most preferable in terms of operating efficiency to use the high-pressure stage exhaust steam.

  As shown in FIG. 3, a through hole formed in the partition member 32 of the blade ring integrated partition member 30 is used as a flow path for supplying the cooling steam that has cooled the divided space 29 to the reheated steam and supplying it to the turbine section 34 is used. In this structure, the cooling steam and the reheat steam join at the reheat steam inlet 28 and are supplied to the turbine section.

FIG. 4 is a first modification of the other embodiment described above. In this modified example, the flow path for supplying the cooling steam that has cooled the divided space 29 to the turbine portion and joining the reheated steam is different. That is, in this modified example, the steam flows through the blade ring portion 31 and is supplied to the downstream stage (for example, the third stage) of the turbine section where the temperature of the reheated steam is lowered. Therefore, by low-temperature cooling steam from the reheat steam merge, it is possible to reduce the temperature drop of the reheat steam flowing in the turbine section. A number of steam flow paths 35 are provided at appropriate pitches in the circumferential direction of the blade ring portion 31.

Moreover, the 2nd modification shown in FIG. 5 differs in the flow path which supplies the cooling steam which cooled the division | segmentation space 29 to a turbine part, and merges with a reheat steam similarly to the 1st modification. That is, in this modified example, the steam passes through the steam passage 36 provided through the convex portion 21a of the outer casing 21, and is supplied to the downstream stage (for example, three cross sections) of the turbine section where the temperature of the reheat steam is lowered. . Therefore, as in the first modification, by a low temperature of cooling steam from the reheat steam merge, it is possible to reduce the temperature drop of the reheat steam flowing in the turbine section.
In addition, about the through-hole 34 and the steam flow paths 35 and 36 mentioned above, any one may be employ | adopted or you may use together combining suitably.

As described above, according to the steam turbine structure of the present invention, the blade ring-integrated partition member 30 is used at least in the first stage close to the regeneration steam inlet 28. Therefore, the regeneration steam inlet section 28 and the turbine section having a high steam temperature. On the upstream side (for example, the first stage, the second stage, etc.), the high-temperature reheated steam does not directly contact the inner wall surface of the outer casing 21, so that it is not easily affected by heat. Therefore, it is possible to prevent or suppress the occurrence of thermal stress and deformation acting on the outer casing 21, avoid the local high temperature of the outer casing 21 and excessive temperature gradient in the axial direction, and the outer casing. 21 steam leakage can be prevented.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

It is sectional drawing which shows the principal part of an intermediate pressure stage as one Embodiment of the steam turbine casing structure which concerns on this invention. 1 is a cross-sectional view showing a schematic configuration of a high and intermediate pressure stage of a reheat turbine as an example of a steam turbine casing structure. It is sectional drawing which shows the principal part of an intermediate pressure stage as other embodiment of the steam turbine casing structure which concerns on this invention. It is sectional drawing which shows the 1st modification of other embodiment shown in FIG. It is sectional drawing which shows the 2nd modification of other embodiment shown in FIG. It is sectional drawing of the principal part which shows the said conventional turbine casing structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Steam turbine 21 Outer casing 21a Convex part 22 Rotor 26 Medium pressure stage moving blade 27 Medium pressure stage stationary blade 28 Steam inlet part 29 Divided space 30 Blade ring integral partition member 31 Blade ring part 32 Partition member 33 Concave part 34 Through hole 35, 36 Steam flow path

Claims (1)

In the steam turbine casing structure in which a steam inlet portion for introducing steam supplied to the turbine section into the vehicle compartment is divided by a partition member that blocks contact between the steam and the vehicle interior wall surface,
The steam inlet portion is divided by a blade ring integrated partition member in which a blade ring supporting at least one stage of stationary vanes from the upstream side of the turbine portion and the partition member are integrated, and the blade ring integrated type Injecting high-pressure stage exhaust steam as cooling steam into the partition space formed between the partition member and the blade ring-integrated partition member by fitting the convex portion of the vehicle interior wall surface to the partition member,
A steam turbine casing structure comprising a steam flow path through which the cooling steam passes through the divided space and is supplied to a downstream stage of the turbine section .

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