JP2014231798A - Steam turbine casing assembly structure and steam turbine casing assembly method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam turbine casing assembly structure capable of easily adjusting a gap between a head of a hold-down bolt and a washer in assembling an inner casing and an outer casing.SOLUTION: According to an embodiment, a steam turbine casing assembly structure is provided in which an inner casing 2 is accommodated in an outer casing 3, the inner casing 2 is configured to be divided into an upper half and a lower half on a horizontal surface, and the inner casing 2 is assembled into the outer casing 3. Furthermore, the casing assembly structure comprises: a hold-down bolt 1 for securing the lower half of the inner casing 2 to the outer casing 3; a washer 15 attached to a shaft 1b of the hold-down bolt 1 with a predetermined gap from a head 1a of the hold-down bolt 1; and a gap adjustment member provided in the washer for adjusting a width of the gap.

Description

  Embodiments described herein relate generally to a steam turbine casing assembly structure and a casing assembly method thereof.

  In general, a low-pressure casing of a steam turbine is composed of an inner casing and an outer casing in order to relieve thermal stress. This low-pressure casing is structured to be divided into an upper half and a lower half on a horizontal plane passing through the rotor shaft (see, for example, Patent Document 1). In such a low-pressure casing, the lower half of the inner casing is fixed to the outer casing by using a stepped hexagon bolt called a hold-down bolt in order to suppress horizontal movement.

  In this structure, an appropriate clearance (hereinafter also referred to as a gap) between the internal casing and the head of the holddown bolt in the axial direction of the holddown bolt in consideration of thermal deformation due to thermal expansion of the internal casing. It is necessary to provide. Conventionally, a structure in which the clearance is adjusted with a washer is employed.

  Specifically, as shown in FIG. 6, the low-pressure casing having a double structure of the inner casing 2 and the outer casing 3 is assembled by housing the inner casing 2 in the outer casing 3 and then holding it. The clearance between the head of 1 and the washer 4 is measured. Next, when the clearance is not within the proper range, the thickness of the washer 4 is adjusted by machining at the construction site so as to be within the proper range.

JP 2002-235505 A (FIG. 2)

  Therefore, the structure shown in FIG. 6 requires a process for inspecting the thickness of the washer 4 and a machining operation for adjusting the thickness of the washer 4. Therefore, the work is stagnated and the assembly time is increased. There is.

  Further, in order to adjust the thickness of the washer 4, a processing facility is indispensable, but the processing facility may not be owned at the local construction site. In that case, since it takes time to secure the processing equipment, there is a problem that the assembly process of the internal compartment 2 and the external compartment 3 is further delayed.

  A problem to be solved by an embodiment of the present invention is that a casing of a steam turbine capable of easily adjusting a gap between a head of a hold-down bolt and a washer when assembling an inner casing and an outer casing. To provide an assembly structure and a method for assembling the passenger compartment.

  In order to achieve the above object, a casing assembly structure of a steam turbine according to an embodiment of the present invention includes an inner casing housed in an outer casing, and the inner casing being a horizontal plane in an upper half portion and a lower half portion. In a casing assembly structure of a steam turbine for assembling the inner casing in the outer casing, a hold down bolt for fixing the lower half of the inner casing to the outer casing, A washer portion mounted on the shaft portion of the holddown bolt with a predetermined gap with respect to the head of the holddown bolt, a gap adjusting member provided on the washer portion and adjusting the width of the gap; It is characterized by providing.

  A steam turbine casing assembly method according to an embodiment of the present invention includes an inner casing and an outer casing, and the inner casing is divided into an upper half and a lower half on a horizontal plane, In the steam turbine casing assembly method for assembling the inner casing in the casing, a storing step of storing the lower half of the inner casing in the outer casing, and a lower portion of the inner casing after the storing step. A washer for installing the washer portion, whose thickness is adjusted, in the internal compartment so that the gap between the head of the hold-down bolt for fixing the half portion to the external compartment and the washer portion is a predetermined gap. And a bolt fastening step of fastening the hold-down bolt and fixing the lower half of the internal compartment to the external compartment after the washer part placement step.

  According to the embodiment of the present invention, it is possible to easily adjust the gap between the head of the hold-down bolt and the washer when assembling the inner casing and the outer casing.

1 is a perspective view showing an internal compartment and an external compartment to which a first embodiment of a steam turbine compartment assembly structure according to the present invention is applied. FIG. FIG. 2 is an enlarged elevational view showing a joint portion between the internal compartment and the external compartment of FIG. 1. It is an enlarged view which shows the structure of the head vicinity in the holddown bolt of FIG. FIG. 3 is an exploded cross-sectional view showing a mode in which a gap adjusting member is provided on the washer of FIG. It is a disassembled sectional view which shows the connection part of an internal compartment and an external compartment in 2nd Embodiment of the compartment assembly structure of the steam turbine which concerns on this invention. It is an enlarged elevation view which shows the connection part of an internal compartment and an external compartment in the conventional low pressure turbine.

  Embodiments of a steam turbine casing assembly structure according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing an internal compartment and an external compartment to which a first embodiment of a steam turbine compartment assembly structure according to the present invention is applied. FIG. 2 is an enlarged elevation view showing a joint portion between the internal compartment and the external compartment of FIG. FIG. 3 is an enlarged view showing the structure in the vicinity of the head in the hold-down bolt of FIG. 4 is an exploded cross-sectional view showing a mode in which a gap adjusting member is provided on the washer of FIG.

  In the following embodiment, the same or corresponding parts as those in the conventional configuration shown in FIG. Further, in FIG. 1, the low-pressure turbine rotor is omitted to simplify the drawing.

  As shown in FIG. 1, the low-pressure turbine of the steam turbine is configured in a double casing structure of an outer casing 3 and an inner casing 2 accommodated in the outer casing 3. Each of the outer casing 3 and the inner casing 2 is a horizontal plane and has an upper and lower half-divided structure, but only the lower half is shown in FIG.

  Four support portions 10 as support portions are installed inside the external casing 3. The internal casing 2 houses a low-pressure turbine rotor (not shown) inside. The lower half of the inner casing 2 is formed such that the four projecting portions 11a to 11d project outward in the horizontal direction. The overhanging portions 11 a to 11 d of the internal compartment 2 are supported by being in contact with four support portions 10 provided in the external compartment 3.

  As shown in FIG. 2, bolt holes 12 are formed in the overhang portions 11 a to 11 d of the internal casing 2 so as to penetrate in the vertical direction. A female screw hole 14 is formed in each support portion 10 of the external casing 3.

  The overhang portions 11 a to 11 d of the internal compartment 2 are fixed to the support portion 10 of the external compartment 3 by the hold down bolt 1. Specifically, as shown in FIG. 2, the shaft portion 1 b of the hold-down bolt 1 is inserted into the bolt holes 12 of the overhang portions 11 a to 11 d, and the tip portion 1 c of the hold-down bolt 1 is passed through the washer 13 to the support portion. 10 female screw holes 14 are fastened. The washer 13 is formed with a central hole 13a through which the tip 1c of the hold-down bolt 1 is inserted.

  In this way, the lower half of the inner casing 2 is fixed to the outer casing 3, and the horizontal movement is suppressed.

  A washer portion 15 is attached to the shaft portion 1b of the hold-down bolt 1 between the head portion 1a of the hold-down bolt 1 and the upper surfaces of the overhang portions 11a to 11d. As shown in FIG. 3, the washer portion 15 is divided in two in the thickness direction into a receiving washer 16 and an adjustment washer 17 that can be adjusted in the vertical direction with respect to the receiving washer 16. As shown in FIG. 4, the receiving washer 16 and the adjustment washer 17 are formed in an annular shape having center holes 16 a and 17 a having the same diameter at the center. The receiving washer 16 has a recess 16b on the upper surface. The lower part of the adjustment washer 17 is accommodated in the recess 16b.

  By the way, considering the thermal deformation due to the thermal expansion of the internal casing 2 as described above, an appropriate clearance (in the axial direction of the holddown bolt 1) between the internal casing 2 and the head 1a of the holddown bolt 1 ( It is necessary to provide a gap. Specifically, it is necessary to adjust the gap C between the lower surface of the head 1a of the hold-down bolt 1 and the upper surface of the washer portion 15 to be an appropriate value of 0.45 to 0.50 mm.

  Therefore, in this embodiment, as shown in FIG. 4, an adjustment shim 18 as a gap adjustment member formed from carbon steel is provided between the receiving washer 16 and the adjustment washer 17. The adjustment shim 18 has a central hole 18a having the same diameter as the receiving washer 16 and the adjustment washer 17 in the center and is formed in an annular shape. A plurality of adjustment shims 18 having the same diameter and different thicknesses are prepared.

  The receiving washer 16 and the adjustment shim 18 are formed with four insertion holes 16c and 18b through which, for example, four set screws 20 are inserted in the circumferential direction. Similarly, the adjustment washer 17 has four female screw holes 17b into which the set screws 20 are screwed in the circumferential direction. The insertion holes 16c and 18b and the female screw hole 17b are formed at positions corresponding to each other.

  Accordingly, after the set screw 20 is inserted into the insertion holes 16c and 18b of the receiving washer 16 and the adjustment shim 18, the tip end portion is screwed into the female screw hole 17b, whereby the receiving washer 16, the adjustment washer 17 and the adjustment shim 18 are obtained. It is fixed integrally. The shaft portion 1b of the hold-down bolt 1 is inserted through the center holes 16a, 17a, and 18a of the receiving washer 16, the adjustment washer 17, and the adjustment shim 18, respectively.

  When the steam turbine is assembled, the adjustment shim 18 acts to adjust the gap C between the lower surface of the head 1 a of the hold-down bolt 1 and the upper surface of the washer portion 15. At this time, when the gap C is made narrower, the adjustment shim 18 having a larger thickness is attached between the washer 16 and the adjustment washer 17. On the other hand, in order to make the gap C wider, the adjustment shim 18 having a thinner thickness is mounted between the washer 16 and the adjustment washer 17.

  Next, the compartment assembly method and operation of this embodiment will be described.

  First, the lower half of the internal compartment 2 is stored in the external compartment 3. Next, the washer portion 15 having the thickness adjusted by selecting the shim 18 for adjustment is adjusted so that the gap C between the lower surface of the head 1a of the holddown bolt 1 and the upper surface of the washer portion 15 becomes an appropriate value. Installed in the overhanging portions 11 a to 11 d of the chamber 2.

  Here, the washer portion 15 is integrated in advance by inserting a set screw 20 into the insertion holes 16c and 18b of the receiving washer 16 and the adjustment shim 18 and screwing the set screw 20 into the female screw hole 17b of the adjustment washer 17. deep.

  And after inserting the shaft part 1b of the holddown bolt 1 in the center holes 16a, 17a, 18a of the receiving washer 16, the adjustment washer 17 and the adjustment shim 18 of the washer part 15, the overhanging parts 11a to 11d of the internal casing 2 are inserted. The shaft portion 1b of the hold-down bolt 1 is inserted into the bolt hole 12 of the first and second ends, and the front end portion 1c of the hold-down bolt 1 is fastened to the female screw hole 14 of the support portion 10 of the outer casing 3 through the center hole 13a of the washer 13. .

  As a result, the lower half of the internal compartment 2 is fixed to the external compartment 3.

  Thus, in the present embodiment, the adjustment shim 18 is selected so that the washer portion 15 is moved so that the gap C between the lower surface of the head 1a of the holddown bolt 1 and the upper surface of the washer portion 15 becomes an appropriate value. The thickness is adjusted. Therefore, when assembling the inner casing 2 and the outer casing 3, the gap C between the head 1a of the hold-down bolt 1 and the washer portion 15 can be easily adjusted. As a result, the assembly measurement step and the machining step for adjusting the thickness of the washer portion that have been conventionally performed can be omitted, and the assembly step can be shortened.

  Next, a modification of the present embodiment will be described with reference to FIGS.

  2 to 4, the lower part of the adjustment washer 17 is mounted in the recess 16 b of the receiving washer 16. In this modification, the lower part of the adjustment washer 17 is fitted in the recess 16 b of the receiving washer 16. The receiving washer 16, the adjustment shim 18 and the set screw 20 for integrating the adjustment shim 18 have a horizontal surface of the overhanging portions 11a to 11d of the internal casing 2 as shown in FIGS. It is attached so as to face.

  Accordingly, in this modification, the recess 16b serves as a guide for assembling the adjustment shim 18 by fitting the lower portion of the adjustment washer 17 into the recess 16b of the reception washer 16, and therefore the receiving washer 16 The adjustment shim 18 can be easily assembled. As a result, the assembly time can be shortened.

  Moreover, in this modification, the set screw 20 can be prevented from dropping when the set screw 20 is damaged by attaching the head so that the head faces the horizontal surface of the overhang portions 11a to 11d of the internal casing 2. It becomes possible to improve reliability.

(Second Embodiment)
FIG. 5 is an exploded cross-sectional view showing a joint portion between an internal compartment and an external compartment in a second embodiment of the steam turbine compartment assembly structure according to the present invention. The same parts as those in the first embodiment will be described with the same reference numerals.

  In the present embodiment, as shown in FIG. 5, the height adjustment shim 22 and the washer 13 are housed in this order in the recesses 10 a of the four support portions 10 of the external casing 3. Here, as with the adjustment shim 18 of the first embodiment, a plurality of height adjustment shims 22 having the same diameter and different thicknesses are prepared at a local construction site. The height adjusting shim 22 has a center hole 22a having the same diameter as the center hole 13a of the washer 13, and is formed in an annular shape.

  As described above, according to the present embodiment, the height adjustment shim 22 is provided in the support portion 10 of the outer casing 3, so that the height of the inner casing 2 with respect to the outer casing 3 can be adjusted. . For this reason, the height of the internal casing 2 can be adjusted without having processing facilities at the local construction site, and the work efficiency at the construction site can be increased. Other configurations and operations are the same as those in the first embodiment, and thus description thereof is omitted.

(Other embodiments)
Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  For example, the configuration of the second embodiment may be combined with the configuration of the first embodiment.

  Moreover, although the said 1st Embodiment demonstrated the example applied to the low pressure turbine of the steam turbine, it is applicable not only to this but a high pressure turbine.

  DESCRIPTION OF SYMBOLS 1 ... Hold down bolt, 1a ... Head, 1b ... Shaft part, 1c ... Tip part, 2 ... Internal compartment, 3 ... External compartment, 4 ... Washer, 10 ... Support part, 10a ... Concave part, 11a-11d ... Overhang part, 12 ... bolt hole, 13 ... washer, 13a ... center hole, 14 ... female screw hole, 15 ... washer part, 16 ... receiving washer, 16a ... center hole, 16b ... recessed part, 16c ... insertion hole, 17 ... adjustment washer 17a ... center hole, 17b ... female screw hole, 18 ... adjustment shim, 18a ... center hole, 18b ... insertion hole, 20 ... set screw, 22 ... height adjustment shim, 22a ... center hole, C ... gap

Claims (7)

A steam turbine casing assembly structure in which an inner casing is housed in an outer casing, the inner casing is divided into an upper half portion and a lower half portion in a horizontal plane, and the inner casing is assembled in the outer casing. In
A hold down bolt for fixing the lower half of the internal compartment to the external compartment;
A washer portion mounted on the shaft portion of the hold-down bolt with a predetermined gap with respect to the head of the hold-down bolt;
A gap adjusting member that is provided in the washer and adjusts the width of the gap;
A casing assembly structure for a steam turbine, comprising:   The steam turbine casing assembly structure according to claim 1, wherein the washer portion is divided into two in the thickness direction, and the gap adjusting member is provided between the two washers.   3. The steam turbine casing assembly structure according to claim 2, wherein the gap adjusting member is an adjustment shim that adjusts the width of the gap.   The steam turbine casing assembly structure according to claim 2 or 3, wherein the two divided washers and the adjustment shim are fastened via a set screw.   The casing assembly structure for a steam turbine according to any one of claims 2 to 4, wherein the two divided washers are fitted and integrated.   The height adjustment shim which adjusts the height of the said internal compartment with respect to the said external compartment is provided in the support part to the said internal compartment in the said external compartment. The steam turbine casing assembly structure according to one item. A steam turbine casing assembly method comprising an inner casing and an outer casing, wherein the inner casing is divided into an upper half and a lower half in a horizontal plane, and the inner casing is assembled in the outer casing. In
A storage step of storing the lower half of the internal compartment in the external compartment;
After the storing step, the thickness was adjusted so that the gap between the head of the hold-down bolt for fixing the lower half of the internal compartment to the external compartment and the washer is a predetermined gap. A washer part installation step for installing the washer part in the internal compartment;
After the washer part installation step, a bolt fastening step of fastening the holddown bolt and fixing the lower half of the internal compartment to the external compartment;
A method for assembling a casing of a steam turbine, comprising:

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