JP2013130151A - Casing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress oval deformation of an inner casing by reducing rigidity of a flange while retaining function of such a structure that the inner casing is supported by a rib of an outer casing.SOLUTION: A casing structure includes: an inner casing 3 which allows a rotor to insert through the interior thereof and is formed by connecting, through bolting, respective flange parts 6, 7 of an inner casing upper half part 4 and an inner casing lower half part 5 vertically bi-sected to each other; and the outer casing having the rib for supporting the inner casing 3. The casing structure further includes: support members 9 which are projected from the flange parts 6, 7 to the outer peripheral side and are mounted on the rib; and slits 11, 12 which are provided in the flange parts and the support members and divide the flange parts 6, 7 and the support members 9 into plurality of pieces in an axial direction of the rotor, wherein the support members 9 are divided into a plurality of support pieces 13.

Description

  The present invention relates to a casing structure of a steam turbine, and more particularly to a casing structure having a double casing structure composed of an inner casing and an outer casing.

  The steam turbine casing used in thermal power and nuclear power plants includes an internal casing (inner car) that houses the turbine rotor and the interior for the purpose of reducing metal stress due to thermal expansion and contraction. Some have a double compartment structure composed of an external compartment (external vehicle) that accommodates the compartment (see, for example, Patent Document 1).

  The inner compartment has an upper half of the inner compartment and a lower half of the inner compartment, which are divided into two parts vertically in a plane including the central axis of the rotor. The lower half is fastened with bolts at a flange protruding in the rotor radial direction. Similarly, the external compartment has an upper half of the external compartment and a lower half of the external compartment, which are divided vertically.

  Since the turbine casing is thermally expanded and contracted by the internal high-temperature gas, the turbine casing is designed in consideration of this deformation. However, it is known that this deformation is not a uniform deformation in the circumferential direction but an elliptical deformation (hereinafter referred to as oval deformation) that is long in the vertical direction or the horizontal direction due to the rigidity of the flange portion. .

  FIG. 7 is a diagram for explaining the oval deformation on the upstream side of the turbine casing. The broken line indicates the outer shape of the inner casing 3 before the deformation, and the one-dot chain line indicates that the inner casing 3 is assumed to be uniformly thermally expanded. The solid line shows the outer shape of the internal compartment 3 after the actual oval deformation. As shown in FIG. 6, the oval deformation on the upstream side of the inner casing 3 becomes larger when exposed to a higher temperature gas, while the upper and lower connecting flange portions 6 and 7 provided on the side of the turbine casing are Since the deformation of the side portion is reduced by being cooled by the outside air temperature, the cross section of the passenger compartment becomes a vertically long oval deformation.

  FIG. 8 is a diagram for explaining the oval deformation on the downstream side of the turbine casing, in which the broken line indicates the outer shape of the inner casing 3 before the deformation, and the alternate long and short dash line assumes that the inner casing is thermally expanded uniformly. 3 shows the outer shape, and the solid line shows the outer shape of the internal casing 3 after the actual oval deformation. As shown in FIG. 7, although the expansion amount on the downstream side is smaller than that on the upstream side, it is dragged by the flange deformation on the upstream side, resulting in a horizontally long oval deformation.

  Since the clearance between the tip of the moving blade fixed to the rotor and the inner peripheral surface of the turbine casing preferably varies uniformly, the oval deformation needs to be less than the allowable value. Therefore, it is preferable that the flange portions 6 and 7 that cause the oval deformation have a structure that allows a certain degree of deformation while having the necessary strength. As a technique for suppressing oval deformation, Patent Document 2 describes a technique for reducing the rigidity of the flange portion by forming a slit in the flange portion.

  Further, as a structure of the turbine casing, there is known a structure (external vehicle support type) in which the inner casing 3 is supported by the lower half 2 of the outer casing as shown in FIG. In this casing structure, the inner casing 3 is supported by the lower half 2 of the outer casing that is supported by the turbine mount 1. The internal compartment 3 includes an internal compartment upper half 4 and an internal compartment lower half 5.

The inner casing upper half 4 and the inner casing lower half 5 protrude in the radial direction of the rotor at the abutment surface between the inner casing upper half 4 and the inner casing lower half 5, and the rotor The flange portions 6 and 7 extending in the axial direction are fastened with bolts 8.
The inner casing 3 is supported by the outer casing lower half 2 via a support member 109 protruding in the horizontal direction from the flange portion 7 of the inner casing lower half 5.

JP 2002-235505 A JP 2007-327448 A

  By the way, in the case of adopting a vehicle compartment structure that supports the internal compartment 3 with the lower half 2 of the external compartment as described above, the support member 109 further enhances the rigidity of the flange portion, thereby promoting the oval deformation. There is a problem of being done. Furthermore, even when a slit is formed in the flange portion 7, the support member 109 closes the slit, and thus there is a problem that the rigidity is further increased.

  The present invention has been made in consideration of such circumstances, and its object is to reduce the rigidity of the flange while maintaining the function of the structure in which the internal compartment is supported by the ribs of the external compartment, An object of the present invention is to provide a vehicle compartment structure capable of suppressing oval deformation of a compartment.

In order to achieve the above object, the present invention provides the following means.
In the case structure of the present invention, the rotor extending in the axial direction is inserted into the interior, and the flange portions of the upper half portion of the internal compartment and the lower half portion of the internal compartment are bolted to each other. And an outer casing having a rib that surrounds the inner casing and supports the inner casing, protrudes from the flange portion to the outer peripheral side, and is placed on the rib. The flange portion and the support member are formed with slits that divide the flange portion and the support member into a plurality of pieces in the axial direction, and the support member is divided into a plurality of support pieces. It is characterized by that.

  According to the above configuration, in the vehicle interior structure in which the internal compartment is supported by the ribs of the external compartment, the support member protruding from the flange portion has a slit formed in addition to the flange portion of the internal compartment. As a result, the rigidity of the flange can be reduced while maintaining the function of the structure in which the inner casing is supported by the ribs of the outer casing. Thereby, the oval deformation of the internal casing can be suppressed, and the gap between the rotor and the internal casing can be made more uniform.

  Further, in the above-described vehicle interior structure, a restriction member that extends in the axial direction and connects the plurality of support pieces while allowing the movement of the plurality of support pieces in the axial direction is engaged with the end portion of the support member. It is preferable that

  According to the said structure, the relative movement of the vertical direction of adjacent support pieces can be controlled, and by extension, the rigidity of the vertical direction of a support member can be improved.

  Further, in the vehicle interior structure, the restricting member and the support member may include a dovetail groove extending in the axial direction on one of the restricting member and the support member, and the dovetail groove on the other. It is preferable that they are engaged with each other by ants provided to face each other.

  Further, in the above-described vehicle interior structure, in at least one pair of adjacent support pieces, a protrusion extending in the protruding direction of the support member is formed on one surface of two surfaces adjacent via the slit, and the other surface A concave groove may be formed opposite to the ridge, and the vertical relative movement of the adjacent support pieces may be restricted by complementary engagement between the ridge and the groove.

  According to the said structure, the relative movement of the orthogonal | vertical direction of adjacent support pieces can be controlled with a simpler structure.

  According to the present invention, in the vehicle compartment structure in which the internal compartment is supported by the ribs of the external compartment, a slit is formed in the support member protruding from the flange portion in addition to the flange portion of the internal compartment. As a result, the rigidity of the flange can be reduced while maintaining the function of the structure in which the inner casing is supported by the ribs of the outer casing. Thereby, the oval deformation of the internal casing can be suppressed, and the gap between the rotor and the internal casing can be made more uniform.

It is a schematic structure figure showing the compartment structure concerning the embodiment of the present invention. It is the schematic which shows the support part of the internal compartment in the compartment structure which concerns on embodiment of this invention. It is a perspective view of the flange part of the internal compartment which concerns on 1st embodiment of this invention. It is a perspective view of the flange part of the internal compartment which concerns on 2nd embodiment of this invention. It is a perspective view of the flange part of the internal compartment which concerns on 3rd embodiment of this invention. It is a perspective view of the flange part of the internal compartment which concerns on 4th embodiment of this invention. It is a figure explaining the oval deformation | transformation of a turbine casing upstream. It is a figure explaining the oval deformation | transformation of a turbine casing downstream. It is a schematic block diagram which shows the conventional vehicle interior structure.

(First embodiment)
Hereinafter, the vehicle interior structure of the first embodiment of the present invention will be described using an example applied to a steam turbine.
As shown in FIG. 1, the vehicle compartment structure includes an outer casing lower half 2 supported by a turbine mount 1 and an inner casing that is supported by the outer casing lower half 2 and that has a rotor (not shown) inserted therein. The chamber 3 and the outer casing upper half 10 that covers the upper side of the inner casing 3 are provided. The lower half 2 of the outer casing has a side wall 2a provided along the inner wall 1a of the turbine mount 1 and a rib 2b provided orthogonal to the side wall 2a. The inner casing 3 is supported by the rib 2b of the lower half 2 of the outer casing.

  The internal compartment 3 includes an internal compartment upper half 4 and an internal compartment lower half 5, and the internal compartment upper half 4 and the internal compartment lower half 5 pass through the central axis of the rotor. Is divided into two in the vertical direction (or in the horizontal direction). The inner casing upper half 4 and the inner casing lower half 5 protrude in the radial direction of the rotor at the abutment surface between the inner casing upper half 4 and the inner casing lower half 5, and the rotor The flange portions 6 and 7 extending in the axial direction are fastened with bolts 8.

FIG. 2 shows a supporting portion of the internal compartment 3 in the compartment structure of the present embodiment, and FIG. 3 shows a perspective view of the flange portions 6 and 7 of the internal compartment 3 of the present embodiment.
As shown in FIGS. 2 and 3, the inner casing 3 is supported by the outer casing lower half 2 via a support member 9 that protrudes in a horizontal direction from the flange section 7 of the inner casing lower half 5. Yes. The flange portion 7 and the support member 9 of the lower half portion 5 of the internal casing are joined by metal welding.

  The support member 9 is a plate-like member having a rectangular shape in plan view and having a predetermined thickness, and an end surface 9 a constituting one long side is joined to the flange portion 7. Further, the lower surface 9b is supported by the lower half 2 of the external casing.

  The flange portions 6 and 7 and the support member 9 are provided with a plurality of slits 11 and 12 extending in a direction orthogonal to the axial direction of the rotor. That is, the flange portion 7 and the support member 9 are divided into a plurality of portions by the slits 11 and 12. The support member 9 is divided into a plurality of strip-shaped support pieces 13, and the base portion of each support piece 13 is joined to the flange portion 7.

Further, the slit 12 of the flange portion 7 is formed continuously with the slit 11 on the extension line of the slit 11 of the support member 9. That is, when the divided flange portions 7 are deformed in the horizontal direction so as to be separated from each other, the deformation is not prevented by the support member 9. In other words, when the flange portion 7 is deformed in the axial direction in a direction away from each other, the support member 9 is also separated in the axial direction according to the flange portion 7.
The thickness of the support member 9 in the vertical direction is set in consideration of insufficient rigidity due to the slit 11. For example, the thickness is increased as compared with a shape without a slit.

According to the embodiment, the slit 11 is formed in the support member 9 in addition to the flange portions 6 and 7, and the rigidity of the inner casing 3 is more uniform by reducing the rigidity of the flange portions 6 and 7. The upstream oval deformation can be reduced. Further, the downstream deformation caused by the upstream flange deformation can also be suppressed.
That is, even in the vehicle compartment structure in which the internal vehicle compartment 3 is supported by the rib 2b of the lower half 2 of the external vehicle compartment, the support member 9 does not prevent the rigidity of the flange portions 6 and 7 from being reduced. The oval deformation can be suppressed, and the gap between the rotor and the inner casing 3 can be made more uniform.

(Second embodiment)
Hereinafter, 2nd embodiment of the vehicle interior structure which concerns on this invention is described based on drawing.
FIG. 4 is a perspective view of the flange portion of the internal compartment according to the present embodiment. In the present embodiment, differences from the first embodiment described above will be mainly described, and description of similar parts will be omitted.
As shown in FIG. 4, the support member 9 </ b> B includes a main body portion 15 joined to the flange portion 7 and a regulating member 16 attached to the main body portion 15. Both the main body 15 and the restriction member 16 have a rectangular parallelepiped shape extending in the rotor axial direction, and the lower surfaces of the main body 15 and the restriction member 16 are on the same plane when the main body 15 and the restriction member 16 are combined. It is configured as follows.

  The main body portion 15 is provided so as to protrude from the flange portion 7 to the outer peripheral side in the radial direction of the rotor, and, like the support member 9 of the first embodiment, a plurality of support pieces 17 are formed by the slits 11B. It is divided into The restricting member 16 is engaged so as to connect a plurality of support pieces 17 to the end of the main body 15 in the protruding direction.

  Specifically, the dovetail groove 18 formed continuously over the plurality of support pieces 17 on the end surface in the projecting direction of the main body 15, and the dovetail formed on the regulating member 16 so as to face the dovetail groove 18. 19 is engaged.

According to the above embodiment, since the regulating member 16 regulates the relative movement of the plurality of support pieces 17 in the vertical direction, the rigidity in the vertical direction of the support member 9B can be increased. On the other hand, in the support piece 17, since the movement of the dovetail groove 18 in the extending direction is allowed, the rigidity of the support member 9B in the rotor axial direction can be reduced.
In the above embodiment, the dovetail groove 18 may be provided in the main body portion of the support member 9 </ b> B, and the dovetail 19 may be formed in the regulating member 16. Further, the engagement between the restriction member 16 and the support member 9B is not limited to the dovetail groove and the dovetail, but may be any shape that allows relative movement in the axial direction of the support piece while preventing the restriction member from falling off.

(Third embodiment)
Next, a passenger compartment structure according to a third embodiment of the present invention will be described based on the drawings.
FIG. 5 is a perspective view showing the passenger compartment structure according to the present embodiment. In the present embodiment, differences from the second embodiment described above will be mainly described, and description of similar parts will be omitted.
As shown in FIG. 5, in the support member 9 </ b> C according to the present embodiment, a regulating shaft 20 is provided instead of the regulating member 16 of the first embodiment.

  Specifically, the support member 9C according to the present embodiment is joined to the flange portion 7, and is regulated through a main body portion 15C divided into a plurality of support pieces 13C and a through hole 21 formed in the main body portion 15C. The shaft 20 is constituted. The through hole 21 is a through hole having a circular cross section formed continuously over the plurality of support pieces 13C. The restriction shaft 20 is a long rod-like member having a circular cross section that is inserted into the through hole 21, and has a length that is substantially the same as the length of the support member in the axial direction.

According to the embodiment, since the restriction shaft 20 restricts the relative movement of the support pieces 13C in the vertical direction, the rigidity of the support member 9C in the vertical direction can be increased. On the other hand, in the support piece 13C, since the movement of the restriction shaft 20 in the extending direction is allowed, the rigidity of the support member 9C in the rotor axis direction can be reduced.
In addition, the cross-sectional shape of the through hole and the restriction shaft is not limited to a circular shape, and may be a rectangular column and a hole having a corresponding shape.

(Fourth embodiment)
Next, a passenger compartment structure according to a fourth embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 6, the support member 9D of the present embodiment is configured by a combination of three types of support pieces 23a, 23b, and 23c (23). In the support pieces 23 adjacent to each other, the protrusions 24 extending in the protruding direction of the support member 9 </ b> D are formed on one side of the two adjacent faces through the slit 11 </ b> D, and the other side faces the protrusion 24. Thus, a concave groove 25 is formed. The ridges 24 and the grooves 25 are configured to complementarily engage each other.

  That is, the adjacent support pieces 23 are connected to each other by the ridge 24 and the groove 25 that protrude in the axial direction. By the complementary engagement of the ridges 24 and the concave grooves 25, the relative movement in the vertical direction between the adjacent support pieces 23 is restricted, and the relative support in the direction in which the adjacent support pieces 23 are separated from each other (axial direction). Movement is allowed.

  The shape of the ridge and the groove is not limited to the shape described above, and may be any shape that restricts the relative movement of the adjacent support pieces 23 in the vertical direction and allows the movement in the axial direction. For example, it is good also as a form of the groove | channel corresponding to a V-shaped protruding item | line and this. It goes without saying that dovetail grooves and dovetails that restrict axial movement are not suitable.

2 ... Lower half of the outer casing, 3 ... Inner casing, 4 ... Upper half of the inner casing, 5 ... Lower half of the inner casing, 6 ... Flange, 7 ... Flange, 9 ... Support member, 10 ... Upper half of external compartment, 11 ... slit, 12 ... slit, 13 ... support piece, 15 ... main body, 16 ... regulating member, 17 ... support piece, 18 ... dovetail groove, 19 ... dovetail, 23 ... support piece, 24 ... ridge, 25 ... groove

Claims (4)

An inner casing in which a rotor extending in the axial direction is inserted into the interior, and each flange portion of the upper half of the inner casing and the lower half of the inner casing is bolted to each other;
An outer casing having a rib surrounding the inner casing and supporting the inner casing,
Protruding from the flange part to the outer peripheral side, and a support member placed on the rib is provided,
A slit that divides the flange portion and the support member into a plurality of portions in the axial direction is formed in the flange portion and the support member, and the support member is divided into a plurality of support pieces. Construction.   A restriction member that extends in the axial direction and connects the plurality of support pieces while allowing the movement of the plurality of support pieces in the axial direction is engaged with the end portion of the support member. The vehicle compartment structure according to claim 1.   The restriction member and the support member are a dovetail groove provided in one of the restriction member and the support member so as to extend in the axial direction, and a dovetail groove provided on the other side to face the dovetail groove. The vehicle interior structure according to claim 2, wherein the vehicle interior structure is engaged with each other. In at least one pair of adjacent support pieces, a protrusion extending in the protruding direction of the support member is formed on one surface of two surfaces adjacent to each other through the slit, and the other surface is opposed to the protrusion. A ditch is formed,
The casing structure according to claim 1, wherein relative movement in the vertical direction between the adjacent support pieces is restricted by complementary engagement between the ridge and the groove.

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