JP2013104297A - Steam turbine low-pressure casing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam turbine low-pressure casing having a bearing box of a casing support type and preventing resonance where vibration of a rotor rotating shaft is increased by a cone part vibrating near a rated rotation speed of a low-pressure steam turbine.SOLUTION: The steam turbine low-pressure casing 21 is configured by horizontally arranging a rotor rotating shaft 22 of the low-pressure turbine, arranging cone parts 23 on both axial sides of the rotor rotating shaft 22, and rotatably supporting the rotor rotating shaft 22 by a bearing 24a of a bearing box 24 disposed in the cone part 23. A dynamic damper 25 with natural frequency adjusted according to a rated rotation speed of the low-pressure turbine is mounted on the cone part 23. The dynamic damper 25 includes: a horizontally extended plate spring 26 with a base end 26a fixed to a bottom surface 23a in the cone part 23; a weight 27 fixed to a distal end 26b of the plate spring 26; and a damper 28 provided between the weight 27 and a floor surface 31.

Description

  The present invention relates to a steam turbine low-pressure casing.

  A conventional steam turbine low-pressure casing 1 shown in FIG. 12 has a bearing box 4 of a casing support type. More specifically, as shown in FIG. 12, the rotor rotating shaft 2 of the low-pressure steam turbine is horizontally disposed in the steam turbine low-pressure casing 1 (the structure of the entire rotor is not shown). ). Cone portions 3 are formed on both sides of the rotor rotation shaft 2 in the axial direction (left-right direction in FIG. 12). These cone portions 3 are concave portions having a shape in which end surfaces on both sides in the axial direction of the steam turbine low-pressure casing 1 are recessed inwardly (in the axial direction) of the steam turbine low-pressure casing 1.

  The bearing boxes 4 are provided in the cone portions 3 on both sides and supported by these cone portions 3 (that is, the steam turbine low-pressure casing 1) (chamber support type). The rotor shaft 2 is rotatably supported by the bearing 4a.

  However, in the case of such a casing-supported steam turbine low-pressure casing 1, the cone portion 3 vibrates as shown in FIG. 13 near the rated speed (for example, 3000 rpm) of the low-pressure steam turbine (rotor rotating shaft 2). There is a mode in which (resonance) occurs, and the vibration of the cone portion 3 may cause a problem that the vibration of the rotor rotating shaft 2 increases. This is because the natural frequency of the cone portion 3 exists near the frequency (for example, 50 Hz) at the rated rotational speed.

  As a countermeasure against such a problem, a conventional steam turbine low-pressure casing 11 in which a bearing box 14 as shown in FIG. 14 is a basic support type is known. Specifically, as shown in FIG. 14, the rotor rotating shaft 12 of the low-pressure steam turbine is horizontally disposed in the steam turbine low-pressure casing 11 (the structure of the entire rotor is not shown). ). Cone portions 13 are formed on both sides of the rotor rotating shaft 12 in the axial direction (left-right direction in FIG. 14).

The bearing housing 14 is disposed outside the cone portion 13 and supported by the foundation 15 (foundation support type), and the rotor rotating shaft 12 is rotatably supported by a bearing 14a provided in the bearing housing 14. doing. In this case, since the edge of the steam turbine low-pressure casing 11 (cone portion 13) and the bearing housing 14 is cut, there is no possibility that the vibration of the rotor rotating shaft 12 increases due to the vibration of the cone portion 13. .
As a prior art document disclosing a steam turbine low-pressure casing using a bearing box as a basic support type, there is Patent Document 1 below.

Japanese Patent No. 3595438

  As described above, in the conventional steam turbine low-pressure casing 11, the bearing box 14 is the basic support type. However, in this case, there is a problem as shown in FIG.

  That is, there is a demerit that the span of the bearing 14a becomes longer in the case of the basic support type compared to the case of the vehicle support type (S1), and there is a risk that the critical speed of the rotor rotating shaft 12 is reduced ( S2). Therefore, at present, in order to avoid such a danger, the critical speed of the rotor rotating shaft 12 is prevented from being lowered by increasing the thickness of the rotor rotating shaft 12 (S3). However, along with this, the bearing 14a (bearing box 14) also becomes larger (S3), and the manufacturing cost of the steam turbine low-pressure casing 11 tends to increase as a whole (S4).

  Therefore, in view of the above circumstances, the present invention avoids the resonance problem that the bearing box is of the cabin support type and the cone portion vibrates near the rated speed of the low-pressure steam turbine and the vibration of the rotor rotating shaft increases. It is an object of the present invention to provide a steam turbine low-pressure casing that can be used.

In the steam turbine low-pressure casing according to the first invention for solving the above-mentioned problems, the rotor rotating shaft of the low-pressure steam turbine is horizontally disposed, and cone portions are formed on both sides in the axial direction of the rotor rotating shaft. In the steam turbine low-pressure casing having a configuration in which the rotor rotation shaft is rotatably supported by a bearing of a bearing box provided in the cone portion,
A dynamic vibration absorber whose natural frequency is adjusted according to the rated rotational speed of the low-pressure steam turbine is attached to the cone portion.

Further, the steam turbine low-pressure casing according to the second invention is the steam turbine low-pressure casing according to the first invention, wherein the dynamic vibration absorber is:
A leaf spring having a base end fixed to the bottom surface in the cone portion and extending horizontally;
A weight fixed to the tip of the leaf spring;
A damper interposed between the weight and the support;
It is the structure provided with.

  The steam turbine low-pressure casing according to the third aspect of the invention is the steam turbine low-pressure casing according to the first aspect of the invention, wherein the dynamic vibration absorber has a weight bonded to the upper part of the inner peripheral surface of the cone portion with an adhesive. It is characterized by that.

The steam turbine low-pressure casing according to a fourth aspect of the invention is the steam turbine low-pressure casing according to the first aspect of the invention, wherein the dynamic vibration absorber is
An elastic body whose upper end is fixed to the upper part of the inner peripheral surface of the cone part and can be expanded and contracted in the vertical direction;
A damper whose upper end is fixed to the upper part of the inner peripheral surface of the cone part;
A weight fixed to a lower end of the elastic body and a lower end of the damper;
It is the structure provided with.

  According to the steam turbine low-pressure casing of the first invention, the rotor rotation shaft of the low-pressure steam turbine is horizontally disposed, and cone portions are formed on both sides in the axial direction of the rotor rotation shaft, and the cone portions are formed in these cone portions. A dynamic vibration absorber whose natural frequency is adjusted in accordance with the rated rotational speed of the low-pressure steam turbine in a steam turbine low-pressure casing having a structure in which the rotor rotating shaft is rotatably supported by a bearing of a provided bearing box However, since it is attached to the cone portion, the dynamic vibration absorber can attenuate the vibration of the cone portion at the rated rotational speed. For this reason, even if the bearing box is a vehicle compartment support type, it is possible to avoid the resonance problem that the cone portion vibrates in the vicinity of the rated rotational speed and the vibration of the rotor rotation shaft increases.

  According to the steam turbine low-pressure casing of the second aspect of the invention, in the steam turbine low-pressure casing of the first aspect of the invention, the dynamic vibration absorber is a leaf spring having a base end fixed to the bottom surface in the cone portion and extending horizontally. Since it is the structure provided with the weight fixed to the front-end | tip of the said leaf | plate spring, and the damper interposed between the said weight and a support part, it is the said 1st invention by the said dynamic vibration absorber, It is characterized by the above-mentioned. Similar effects can be obtained, and the structure of the dynamic vibration absorber is simple and easy to manufacture.

  According to the steam turbine low-pressure casing of the third invention, in the steam turbine low-pressure casing of the first invention, the dynamic vibration absorber has a structure in which a weight is bonded to the upper part of the inner peripheral surface of the cone portion with an adhesive. Therefore, the dynamic vibration absorber can provide the same effects as the first invention. Moreover, since the dynamic vibration absorber weight has a very simple structure in which the weight is bonded with an adhesive, it can be attached to the steam turbine low-pressure casing after manufacture. For this reason, when a resonance problem occurs in the steam turbine low-pressure casing after manufacture, it can be used as a technique for avoiding this resonance problem.

  According to the steam turbine low-pressure casing of the fourth aspect of the invention, in the steam turbine low-pressure casing of the first aspect of the invention, the dynamic vibration absorber is extendable in the vertical direction with the upper end fixed to the upper part of the inner peripheral surface of the cone portion. The elastic body, a damper having an upper end fixed to the upper part of the inner peripheral surface of the cone portion, and a weight fixed to the lower end of the elastic body and the lower end of the damper are characterized in that Therefore, the same effect as the first invention can be obtained by the dynamic vibration absorber, and the structure of the dynamic vibration absorber is simple and easy to manufacture.

1 is a configuration diagram of a steam turbine low-pressure casing according to Embodiment 1 of the present invention. It is the A section enlarged view of FIG. It is a block diagram of the dynamic vibration damper equipped in the steam turbine low-pressure casing according to Embodiment 1 of the present invention. It is a model diagram of the dynamic vibration absorber equipped in the steam turbine low-pressure casing according to Embodiment 1 of the present invention. It is a block diagram of the steam turbine low-pressure casing according to Embodiment 2 of the present invention. It is the B section enlarged view of FIG. It is CC line arrow directional view of FIG. It is a model diagram of the dynamic vibration damper equipped in the steam turbine low-pressure casing according to Embodiment 2 of the present invention. It is a block diagram of the steam turbine low-pressure casing which concerns on Example 3 of this invention. It is the D section enlarged view of FIG. It is an EE arrow directional view of FIG. It is a block diagram of the conventional steam turbine low-pressure casing which used the bearing box as the casing support type. It is a figure which shows the vibration state of the cone part and rotor rotating shaft in the conventional steam turbine low pressure vehicle interior which used the bearing box as the vehicle interior support type. It is a block diagram of the conventional steam turbine low-pressure casing which used the bearing box as the basic support type. It is a figure which shows the problem in the conventional steam turbine low-pressure casing which used the bearing box as the basic support type.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

<Embodiment 1>
The configuration of the steam turbine low-pressure casing according to Embodiment 1 of the present invention will be described with reference to FIGS.

  The steam turbine low-pressure casing 21 of the first embodiment shown in FIG. 1 has a bearing box 24 of a casing support type. More specifically, as shown in FIG. 1, the rotor rotating shaft 22 of the low-pressure steam turbine is horizontally disposed in the steam turbine low-pressure casing 21 (the structure of the entire rotor is not shown). ). Cone portions 23 are formed on both sides of the rotor rotation shaft 22 in the axial direction (left-right direction in FIG. 1). These cone portions 23 are concave portions having a shape in which end surfaces on both sides in the axial direction in the steam turbine low-pressure casing 21 are recessed inside the steam turbine low-pressure casing 21 (in the axial direction).

  The bearing boxes 24 are respectively provided in the cone portions 23 on both sides and are supported by these cone portions 23 (that is, the steam turbine low-pressure casing 21) (chamber support type), and are provided in the bearing casing 24. The rotor rotating shaft 22 is rotatably supported by the bearing 24a.

  A dynamic vibration absorber 25 is attached to the cone portion 23. The dynamic vibration absorber 25 is obtained by adjusting the natural frequency according to the rated rotational speed (for example, 3000 rpm) of the low-pressure steam turbine. That is, the natural frequency of the dynamic vibration absorber 25 is adjusted to be equal to the frequency (for example, 50 Hz) at the rated rotational speed.

  The configuration of the dynamic vibration absorber 25 will be described in detail with reference to FIGS. 2 to 4 show a dynamic vibration absorber 25 attached to the right cone 23. The dynamic vibration absorber 25 attached to the left cone portion 23 has the same configuration as that of the dynamic vibration absorber 25 attached to the right cone portion 23, and therefore illustration and description thereof are omitted here.

As shown in FIGS. 2 and 3, the dynamic vibration absorber 25 includes a leaf spring 26, a weight 27, and a damper 28.
The leaf spring 26 has a base end 26 a fixed to the bottom surface 23 a in the cone portion 23 by fixing means such as welding or a bolt, and extends horizontally (in the axial direction). Accordingly, the leaf spring 26 can vibrate in the vertical direction (vertical direction) as indicated by an arrow a2 in the drawing.
The weight 27 has a rectangular parallelepiped shape, and is fixed to the tip 26b of the leaf spring 26 by fixing means such as welding or bolts. Note that the weight 27 is not limited to a rectangular parallelepiped shape, but may be an appropriate shape. Moreover, as the weight 27, a metal thing, a plastic thing, etc. can be used.
The damper 28 is interposed between the weight 27 and the floor 31 (support) by fixing both ends to the weight 27 and the floor 31 (support) by fixing means such as welding or bolts. ing. The floor surface 31 is fixed to the foundation 32 by a fixing means such as a bolt for maintenance work or the like, and is not connected to the cone portion 23, and therefore does not vibrate together with the cone portion 23. In addition, as a support part which attaches the damper 28, it is not limited to the floor surface 31, What is necessary is just a location which does not vibrate with the cone part 23. FIG.

In the model diagram of FIG. 4, K is the spring constant of the leaf spring 26, M is the mass of the weight 27, and C is the damping coefficient of the damper 28. The dynamic vibration absorber 25 is adjusted by the following [Equation 1] equation (natural frequency equation) by adjusting either or both of the value of the spring constant K of the leaf spring 26 and the value of the mass M of the weight 27. The expressed natural frequency F is adjusted to be equal to the frequency (for example, 50 Hz) at the rated rotational speed of the low-pressure steam turbine.

  As shown in FIGS. 2 and 4, when the cone portion 23 vibrates in the vertical direction (vertical direction) as indicated by the arrow a1, the leaf spring 26, the weight 27 and the damper 28 of the dynamic vibration absorber 25 are also indicated in the vertical direction as indicated by the arrow a2. The damper 28 absorbs the vibration energy and attenuates the vibration. That is, the dynamic vibration absorber 25 is adjusted so that its natural frequency F is equal to the frequency at the rated rotational speed, and thus can attenuate the vibration of the cone portion 23 at the rated rotational speed.

  As described above, according to the steam turbine low-pressure casing 21 of the first embodiment, the rotor rotating shaft 22 of the low-pressure steam turbine is horizontally disposed, and the cone portions 23 are provided on both sides in the axial direction of the rotor rotating shaft 22. In the steam turbine low-pressure casing 21 in which the rotor rotating shaft 22 is rotatably supported by the bearings 24a of the bearing housings 24 provided in the cone portions 23, the rating of the low-pressure steam turbine is Since the dynamic vibration absorber 25 whose natural frequency is adjusted in accordance with the rotational speed is attached to the cone portion 23, the dynamic vibration absorber 25 causes the vibration of the cone portion 23 at the rated rotational speed. Can be attenuated. For this reason, even if the bearing box 24 is a vehicle compartment support type, it is possible to avoid the resonance problem that the cone portion 23 vibrates near the rated rotational speed and the vibration of the rotor rotating shaft 22 increases.

  Moreover, according to the steam turbine low-pressure casing 21 of the first embodiment, the dynamic vibration absorber 25 includes a leaf spring 26 that has a base end 26a fixed to the bottom surface 23a in the cone portion 23 and extends horizontally, Since the structure is provided with a weight 27 fixed to the tip 26b of the spring 26 and a damper 28 interposed between the weight 27 and the floor surface 31, the structure of the dynamic vibration absorber 25 is Simple and easy to manufacture.

<Embodiment 2>
The configuration of the steam turbine low-pressure casing according to the second embodiment of the present invention will be described with reference to FIGS.

  The steam turbine low-pressure casing 41 of the second embodiment shown in FIG. 5 has a bearing box 44 of a casing support type. More specifically, as shown in FIG. 5, the rotor rotation shaft 42 of the low pressure steam turbine is horizontally disposed in the steam turbine low pressure casing 41 (the structure of the entire rotor is not shown). ). Cone portions 43 are formed on both sides of the rotor rotation shaft 42 in the axial direction (left-right direction in FIG. 5). These cone portions 43 are concave portions having a shape in which end surfaces on both sides in the axial direction of the steam turbine low-pressure casing 41 are recessed inside the steam turbine low-pressure casing 41 (in the axial direction).

  The bearing boxes 44 are respectively provided in the cone portions 43 on both sides and are supported by these cone portions 43 (that is, the steam turbine low-pressure casing 41) (chamber support type), and are provided in the bearing casing 44. The rotor rotating shaft 42 is rotatably supported by the bearing 44a.

  A dynamic vibration absorber 45 is attached to the cone portion 43. The dynamic vibration absorber 25 is obtained by adjusting the natural frequency according to the rated rotational speed (for example, 3000 rpm) of the low-pressure steam turbine. That is, the natural frequency of the dynamic vibration absorber 25 is adjusted to be equal to the frequency (for example, 50 Hz) at the rated rotational speed.

  Based on FIGS. 6-8, the structure of the dynamic vibration damper 45 is explained in full detail. 6 to 8 show the dynamic vibration absorber 45 attached to the right cone portion 43. Since the dynamic vibration absorber 45 attached to the left cone portion 43 has the same configuration as that of the dynamic vibration absorber 45 attached to the right cone portion 43, illustration and description thereof are omitted here.

  As shown in FIGS. 6 and 7, the dynamic vibration absorber 45 has a configuration in which a weight 47 is bonded to an upper portion 43 a-1 of the inner peripheral surface 43 a of the cone portion 43 with an adhesive 46. The weight 47 has a plate shape and an arc shape (FIG. 7) along the circumferential direction of the inner peripheral surface 43 a of the cone portion 43. Note that the weight 47 is not limited to an arc shape, but may have an appropriate shape. Moreover, as the weight 47, a metal plate, a plastic plate, etc. can be used.

  As shown in the model diagram of FIG. 8, the adhesive 46 functions as a state in which a spring (elastic body) 46a and a damper 46b are connected in parallel during vibration. That is, the adhesive 46 only needs to exhibit a function as a spring (elasticity) and a damper (damping) during vibration, and an epoxy adhesive, a silicon adhesive, or the like can be used.

  In the model diagram of FIG. 8, K is the spring constant of the adhesive 46 that functions as the spring 46a, M is the mass of the weight 47, and C is the damping coefficient of the adhesive 46 that functions as the damper 46b. The dynamic vibration absorber 45 is expressed by the above [Expression 1] by adjusting either or both of the value of the spring constant K of the adhesive 46 (spring 46a) and the value of the mass M of the weight 47. The natural frequency F is adjusted to be equal to the frequency (for example, 50 Hz) at the rated speed of the low-pressure steam turbine.

  As shown in FIGS. 6 and 8, when the cone portion 43 vibrates in the vertical direction (vertical direction) as indicated by arrow b1, the adhesive 46 (spring 46a, damper 46b) and weight of the dynamic vibration absorber 45 are indicated as indicated by arrow b2. 27 also vibrates in the vertical direction, and the adhesive 46 functioning as a damper 46b absorbs the vibration energy and attenuates the vibration. That is, the dynamic vibration absorber 45 is adjusted so that its natural frequency F is equal to the frequency at the rated rotational speed, and thus can attenuate the vibration of the cone portion 43 at the rated rotational speed.

  As described above, according to the steam turbine low-pressure casing 41 of the second embodiment, the rotor rotating shaft 42 of the low-pressure steam turbine is horizontally disposed, and the cone portions 43 are disposed on both sides in the axial direction of the rotor rotating shaft 42. In the steam turbine low-pressure casing 41 having a configuration in which the rotor rotating shaft 42 is rotatably supported by bearings 44a of bearing boxes 44 provided in the cone portions 43, the rating of the low-pressure steam turbine is Since the dynamic vibration absorber 45 whose natural frequency is adjusted in accordance with the rotational speed is attached to the cone portion 43, the dynamic vibration absorber 45 causes the vibration of the cone portion 43 at the rated rotational speed. Can be attenuated. For this reason, even if the bearing box 44 is a vehicle compartment support type, it is possible to avoid the resonance problem that the cone portion 43 vibrates near the rated rotational speed and the vibration of the rotor rotating shaft 42 increases.

  Moreover, according to the steam turbine low-pressure casing 41 of the second embodiment, the dynamic vibration absorber 45 has a configuration in which the weight 47 is bonded to the upper portion 43a-1 of the inner peripheral surface 43a of the cone portion 43 by the adhesive 46. It is characterized by being. Therefore, the dynamic vibration absorber weight 45 has a very simple configuration in which the weight 47 is bonded by the adhesive 46, and can be attached to the steam turbine low-pressure casing 41 after manufacture. For this reason, when a resonance problem occurs in the steam turbine low-pressure casing 41 after manufacture, it can be used as a technique for avoiding this resonance problem.

<Embodiment 3>
Based on FIGS. 9-11, the structure of the steam turbine low-pressure casing which concerns on Example 3 of this invention is demonstrated.

  The steam turbine low-pressure casing 51 of the third embodiment shown in FIG. 9 has a bearing box 54 of a casing support type. More specifically, as shown in FIG. 9, the rotor rotating shaft 52 of the low pressure steam turbine is horizontally disposed in the steam turbine low pressure casing 51 (the structure of the entire rotor is not shown). ). Cone portions 53 are formed on both sides of the rotor rotation shaft 52 in the axial direction (left-right direction in FIG. 9). These cone portions 53 are concave portions having a shape in which end surfaces on both sides in the axial direction of the steam turbine low-pressure casing 51 are recessed inside the steam turbine low-pressure casing 51 (in the axial direction).

  The bearing boxes 54 are respectively provided in the cone portions 53 on both sides and are supported by these cone portions 53 (that is, the steam turbine low-pressure casing 51) (chamber support type), and are provided in the bearing casing 54. The rotor rotating shaft 52 is rotatably supported by the bearing 54a.

  A dynamic vibration absorber 55 is attached to the cone portion 53. The dynamic vibration absorber 55 is obtained by adjusting the natural frequency according to the rated rotational speed (for example, 3000 rpm) of the low-pressure steam turbine. That is, the natural frequency of the dynamic vibration absorber 55 is adjusted to be equal to the frequency (for example, 50 Hz) at the rated rotational speed.

  Based on FIG.10 and FIG.11, the structure of the dynamic vibration damper 55 is explained in full detail. FIG. 10 shows a dynamic vibration absorber 55 attached to the right cone portion 53. Since the dynamic vibration absorber 55 attached to the left cone portion 53 has the same configuration as the dynamic vibration absorber 55 attached to the right cone portion 53, illustration and description thereof are omitted here.

As shown in FIGS. 10 and 11, the dynamic vibration absorber 55 includes a coil spring 56, a weight 57, and a damper 58.
The upper end 56a of the coil spring 56 is fixed to the upper part 53a-1 of the inner peripheral surface 53a of the cone part 53 by fixing means such as welding or bolts.
The damper 58 has an upper end 58a fixed to the upper part 53a-1 of the inner peripheral surface 53a of the cone part 53 by fixing means such as welding or bolts. That is, the coil spring 56 and the damper 58 are connected in parallel.
The weight 57 has a rectangular parallelepiped shape, and is fixed to the lower end 56b of the coil spring 56 and the lower end 58b of the damper 58 by fixing means such as welding or bolts. Note that the weight 57 is not limited to a rectangular parallelepiped shape, but may be an appropriate shape. Moreover, as the weight 57, a metal thing, a plastic thing, etc. can be used.

  In FIG. 11, K is the spring constant of the coil spring 56, M is the mass of the weight 57, and C is the damping coefficient of the damper 58. The dynamic vibration absorber 55 is adjusted by adjusting either or both of the value of the spring constant K of the coil spring 56 and the value of the mass M of the weight 57, so that the natural frequency F expressed by the above [Expression 1] is obtained. Is adjusted to be equal to the frequency (for example, 50 Hz) at the rated rotational speed of the low-pressure steam turbine.

  As shown in FIGS. 10 and 11, when the cone part 53 vibrates in the vertical direction (vertical direction) as indicated by the arrow c1, the coil spring 56, the weight 57 and the damper 58 of the dynamic vibration absorber 55 are also indicated in the vertical direction as indicated by the arrow c2. The damper 58 absorbs the vibration energy and attenuates the vibration. In other words, the dynamic vibration absorber 55 is adjusted so that its natural frequency F is equal to the frequency at the rated rotational speed, and thus the vibration of the cone portion 53 at the rated rotational speed can be attenuated.

  As described above, according to the steam turbine low-pressure casing 51 of the third embodiment, the rotor rotating shaft 52 of the low-pressure steam turbine is horizontally disposed, and the cone portions 53 are disposed on both sides in the axial direction of the rotor rotating shaft 52. In the steam turbine low-pressure casing 51 in which the rotor rotating shaft 52 is rotatably supported by the bearings 54a of the bearing housings 54 provided in these cone portions 53, the rating of the low-pressure steam turbine is Since the dynamic vibration absorber 55 whose natural frequency is adjusted according to the rotational speed is attached to the cone portion 53, the dynamic vibration absorber 55 causes the vibration of the cone portion 53 at the rated rotational speed. Can be attenuated. For this reason, even if the bearing box 54 is a vehicle compartment support type, it is possible to avoid the resonance problem that the cone portion 53 vibrates in the vicinity of the rated rotational speed and the vibration of the rotor rotating shaft 52 increases.

  Moreover, according to the steam turbine low-pressure casing 51 of the third embodiment, the dynamic vibration absorber 55 can be expanded and contracted in the vertical direction with the upper end 56a fixed to the upper portion 53a-1 of the inner peripheral surface 53a of the cone portion 53. Coil spring 56, damper 58 having upper end 58a fixed to upper portion 53a-1 of inner peripheral surface 53a of cone portion 53, and weight 57 fixed to lower end 56b of coil spring 56 and lower end 58a of damper 58 Since the structure is provided, the structure of the dynamic vibration absorber 55 is simple and easy to manufacture.

  In the above description, the coil spring 56 is used as an example of the elastic body. However, the present invention is not limited to this. Any elastic body may be used.

  The present invention relates to a steam turbine low-pressure casing, and the bearing box is useful when applied to a casing-supported steam turbine low-pressure casing.

DESCRIPTION OF SYMBOLS 21 Steam turbine low pressure casing 22 Rotor rotating shaft 23 Cone part 23a Bottom 24 Bearing box 24a Bearing 25 Dynamic vibration absorber 26 Leaf spring 26a Base end 26b End 27 Weight 28 Damper 31 Floor surface 32 Base 41 Steam turbine low pressure casing 42 Rotor rotation Shaft 43 Cone portion 43a Inner peripheral surface 43a-1 Upper portion 44 Bearing box 44a Bearing 45 Dynamic vibration absorber 46 Adhesive 46a Spring 46b Damper 47 Weight 51 Steam turbine low pressure casing 52 Rotor rotating shaft 53 Cone portion 53a Inner peripheral surface 53a-1 Upper part 54 Bearing box 54a Bearing 55 Dynamic vibration absorber 56 Coil spring 56a Upper end 56b Lower end 57 Weight 58 Damper 58a Upper end 58b Lower end

Claims (4)

The rotor rotating shaft of the low-pressure steam turbine is horizontally arranged, and cone portions are formed on both sides in the axial direction of the rotor rotating shaft. The rotor rotating shaft is supported by bearings of bearing boxes provided in these cone portions. In a steam turbine low-pressure casing configured to be rotatably supported,
A steam turbine low-pressure casing, wherein a dynamic vibration absorber whose natural frequency is adjusted in accordance with a rated rotational speed of the low-pressure steam turbine is attached to the cone portion. In the steam turbine low-pressure casing according to claim 1,
The dynamic vibration absorber is
A leaf spring having a base end fixed to the bottom surface in the cone portion and extending horizontally;
A weight fixed to the tip of the leaf spring;
A damper interposed between the weight and the support;
A steam turbine low-pressure casing characterized by comprising In the steam turbine low-pressure casing according to claim 1,
The steam turbine low-pressure casing is characterized in that the dynamic vibration absorber is configured such that a weight is bonded to an upper portion of an inner peripheral surface of the cone portion with an adhesive. In the steam turbine low-pressure casing according to claim 1,
The dynamic vibration absorber is
An elastic body whose upper end is fixed to the upper part of the inner peripheral surface of the cone part and can be expanded and contracted in the vertical direction;
A damper whose upper end is fixed to the upper part of the inner peripheral surface of the cone part;
A weight fixed to a lower end of the elastic body and a lower end of the damper;
A steam turbine low-pressure casing characterized by comprising

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