ITCO20110060A1 - STEAM TURBINE, PALLET AND METHOD - Google Patents

Description

TITLE / TITLE

STEAM TURBINE, BLADE, AND METHOD

KNOWN ART TECHNICAL FIELD

The present invention relates generally to steam turbines and, more specifically, to a stator blade ring in a steam turbine and to a method for making a stator blade ring.

SUMMARY OF KNOWN ART

A steam turbine is a turbomachine that converts the heat and pressure energy of the steam into a rotary motion that can be used to perform the job. For example, steam turbines can be used to drive electric generators or compressors.

To improve the efficiency of the steam turbine, the steam is expanded through a certain number of stages. Each stage usually includes a stator vane diaphragm and a bearing rotor assembly equipped with at least one impeller.

As the steam advances to the later stages of the steam turbine, it is possible that enough energy is absorbed by the steam to condense parts of the steam and thus become so-called wet steam. Furthermore, to obtain a possible corrosive effect, when the wet vapor hits the stator vane diaphragm, the condensate tends to violently impact the stator vane and other diaphragm components. As a result, the stator vanes and other components of each stator vane diaphragm in the later stages of the steam turbine can be damaged, for example, during prolonged exposure to high condensing wet steam.

In modern steam turbines, the production of stator vane diaphragms represents a significant cost, especially in multistage steam turbines having one or more stages, each of which may include one or more separate stator vane diaphragms.

If a stator vane diaphragm is damaged, it may be necessary to shut down the steam turbine and take the damaged stator diaphragm out of service. If on-site repair is not possible, it may be necessary to send the diaphragm offsite for repair or, alternatively, install a new stator diaphragm. Or worse still, if a replacement part is not available, a new stator vane diaphragm may need to be manufactured. Therefore, in addition to the cost of the stator diaphragm, the costs associated with the prolonged inactivity of the steam turbine must be borne.

Consequently, it is necessary to replace the conventional stator vane diaphragm with a model that can be easily repaired and / or replaced, capable of operating in the presence of wet steam, and based on a simple, easily manufactured design.

SUMMARY

In an exemplary embodiment, a stator vane ring for a steam turbine includes a plurality of stator vane modules defining an annular chamber. Each stator vane module comprises an elongated vane portion provided with a first vane shell part and a second vane shell part brazed to the first vane shell part. The elongated blade portion further comprises a longitudinal passage, at least one opening extending through the first blade shell portion and the second blade shell portion towards the longitudinal passage. An inner part brazed to a first longitudinal end of the blade portion, the inner portion comprises a direct hole which forms a portion of the annular chamber, the inner portion further includes an inner longitudinal passage extending from the direct hole to the longitudinal passage. An outer portion brazed to a second longitudinal end of the blade portion and secured to the steam turbine, the outer portion comprises an outer passage communicating with a surface of the steam turbine and the longitudinal passage.

In accordance with another exemplary embodiment, a turbomachinery comprises a rotor assembly containing at least one impeller, a bearing connected to the rotor assembly which supports it in rotation, and a stator vane ring having a plurality of stator vane modules defining a chamber. annular. Each blade module includes at least one elongated blade part having a first blade shell part and a second blade shell part brazed to the first blade shell part, an inner part brazed to a first longitudinal end of at least one part of vanes, the inner part including a direct hole forming a part of the annular chamber and an outer part brazed to a second longitudinal end of at least a part of the vanes and fixed to a surface of the steam turbine. At least one of the vane modules includes a longitudinal passage and at least one opening in at least one part of the vane to allow liquid to enter the longitudinal passage and an internal passage in the interior which extends from the direct hole to the longitudinal passage, so that the liquid flows between the annular chamber and the longitudinal passage. At least one of the vane modules includes a longitudinal passage in at least one part of the vane, an internal passage in the internal part extending from the direct hole to the longitudinal passage to allow liquid to flow between the annular chamber and the longitudinal passage, an external passage in the outer portion extending from the longitudinal passage and an opening to the surface of the turbomachinery so that the liquid flows out of the stator vane ring.

According to another exemplary embodiment, a method of constructing a blade module for a stator blade ring may include the steps of: brazing the first and second edges of a first blade shell part at the edges, first and second, of a second part in the shell of blades; formation of a direct hole in the internal part; formation of an internal passage in the internal part extending from a surface of the internal part to the direct hole; brazing a first longitudinal end of the blade portion to the surface of the inner portion, so that this longitudinal passage communicates with the inner passage; forming an external passage in the external part extending from a first surface to a second surface of the external part; and brazing a second longitudinal end of the blade portion to the first surface of the outer portion, so that the longitudinal passage communicates with the outer passage.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical drawings annexed to the detailed description, and of which they form an integral part, represent one or more embodiments and, together with the description, explain these embodiments. In the drawings:

Figure 1 depicts a steam turbine.

Figure 2 shows a perspective view of an exemplary embodiment.

Figure 3 shows a side view of the exemplary embodiment in Figure 2. Figure 4 shows a cross-sectional view of the exemplary embodiment in Figure 2.

Figures 5 to 7 show an internal part of the exemplary embodiment in Fig. 2.

Figures 8 to 10 show an external part of the exemplary embodiment in Fig. 2.

Figure 11 is a flowchart indicating a method for manufacturing a vane module for a vane ring of a stator according to an exemplary embodiment.

DETAILED DESCRIPTION

The following description of the exemplary embodiments refers to the attached technical drawings. Like reference numerals, occurring in different drawings, represent similar or identical elements. The following detailed description does not limit the invention. On the contrary, the scope of the invention is defined by the included claims. The following embodiments are treated, for reasons of simplicity, in relation to the terminology and structure of a turbomachine provided with a stator and a rotor. However, the embodiments that will be discussed later are not limited to these exemplary systems, but can be applied to other systems. Throughout the detailed description, reference to "an embodiment" means that a particular feature, structure or property described in connection with an embodiment is included in at least one embodiment of the disclosed object. Therefore, the use of the expression "in an embodiment" or "in an embodiment" at different points of the detailed description will not necessarily refer to the same embodiment. Furthermore, the particular characteristics, structures or properties can be combined in one or more embodiments according to the appropriate modality.

To provide a basis for the following analysis relating to the stator vanes according to these exemplary embodiments, Figure 1 schematically shows a turbomachine in the form of a multistage steam turbine 400. Here, the steam turbine 400 comprises a housing (the stator) 420 within which is mounted a certain number of diaphragms for blades 430 disposed along the shaft of the rotor 450 provided with a plurality of rotors of the impeller 440. The shaft 450 is supported radially and axially by the bearings 480.

In operation, the steam turbine draws steam from an inlet 460, through various stages of expansion, and expels it to an outlet 470 which leads to a condenser. At each stage of the turbine, steam is directed from a diaphragm of the stator 430 to a rotor of the impeller 440, thereby converting the heat and pressure energy of the steam into the rotating energy available to operate the shaft of the rotor 450.

Figure 2 shows a part of a vane ring of the stator 12 according to an exemplary embodiment of the present invention. A stator vane ring 12 includes a plurality of the individual stator vane modules 14 extending around the rotor 28 (Fig. 3) in the steam turbine 10. Figure 2 shows two such vane modules 14a and 14b. .

Each stator blade module 14a, 14b includes an elongated blade portion 16, as shown in Figures 2 and 3. Figure 4 shows a transverse view of an elongated blade portion 16 provided with a longitudinal consolidating rib 24 and passages lengthwise 26. As shown in Fig. 4, a part of vanes 116 can also be supplied without consolidation rib 24 and, therefore, can have a single longitudinal passage 26. As discussed in detail below, each part of vanes 16 is made by brazing a first part of blades 18 to a second part of blades 22, along the upstream edge 32 and the downstream edge 34.

As also shown in Figures 2 to 4, each part of vanes 16 comprises a plurality in at least one shell part of vanes 22 and a shell part of vanes 24. In the embodiment of Figures 2 to 4, each opening 36 is a slot formed by the machining of electric discharge. Alternatively, the openings 36 can be made by machining processes, such as drilling or milling, or during the initial production of the vane shell part 22 and the vane shell part 24, for example by molding.

Each blade module 14 comprises an internal part 38 connected to a first longitudinal end of at least one blade part 16, as shown in Fig. 2. In the embodiment shown in Figures 2 to 4, the internal part 38 is brazed to a part of vanes 16, as will be analyzed in more detail below. Each inner part 38 includes a forward hole 42 extending transversely to the longitudinal axis 46 (Fig. 3) of the blade portion 16. The forward hole 42 forms a part of an annular chamber 20 in a blade ring of the stator 12, when each vane module is installed in the steam turbine 10. In order to optimize sealing through the direct holes 12 in adjacent vane modules 14, it is possible to provide at least one end of each direct hole 12 with a groove 48 configured to accommodate a sealing joint. In the embodiment of Figures 2 to 4, the groove 48 is configured to accommodate a toroidal ring.

Each inner part 38 further includes at least one inner passage 44, as shown in Fig. 3, which extends from the direct hole 42 to each longitudinal passage 26. Alternatively, if the consolidating rib 24 terminates before the longitudinal end of the vanes 16, it is then possible to open a single internal passage 44 which communicates with both longitudinal passages 26.

Each stator blade module 14 also includes an outer portion 52 connected to a second longitudinal end of at least one blade portion 16, as shown in Figures 2 and 3. Each outer portion 52 includes at least one outer passage 54 which communicates with each passage longitudinal 26 and to an inner surface of the steam turbine 10, as shown in Figures 2, 9 and 10. Further, in the embodiment of Figures 2 to 4 and 8 to 10, each outer part may include a groove 74 on at least one side. The groove 74 may be configured to accommodate a gasket that provides a seal between adjacent external parts 52 and / or a damping effect to the stator vane ring 12. The stator vane ring 12 may be used in one of the last stages of the steam turbine 10, as shown in Fig. 2. During operation, the condensate from the wet steam, which impacts each part of the blades 14, can enter the longitudinal passage 26 of a part of the blades 16 through one of the openings 36. There are multiple paths to convey condensate into the vane modules 14 before it flows out of the stator vane ring 12, at a point where the condensate is less likely to cause damage to the components of the steam turbine 10. In one path , which can include the stator blade modules 14 above the rotor shaft, condensate can travel downstream through each longitudinal passage 26 and each int 44 in the direct hole 42. The open direct holes 42 in the adjacent blade modules 14, which form the annular chamber 20, extend around the vane ring of the stator 12 and allow condensate to continue to flow downstream as a result of the severity. The condensate can exit the annular chamber 20 and continue on a downstream path through an internal passage 44 of a blade module 14, under the rotor shaft of the steam turbine 10. Finally, the condensate can flow through an external passage 54 towards a surface of a steam turbine outside the vane ring 12.

In another path, the condensate can enter a longitudinal passage 26 of a part of blades 16, under the rotor shaft of the steam turbine 10, and flow through an external passage 54, without first passing through the annular chamber 20 formed by the direct holes 42.

Eliminating condensate from the wet steam advancing through the later stages of the steam turbine 10 can prevent damage to the stator blade ring 12 as well as to the turbine blades 16 and other components downstream of the steam turbine 10. Also , the stator vane ring 12 permits the collection of condensate which may include residual heat for use in other processes.

Some blade modules, for example those located above the rotor shaft of the steam turbine 10, may be devoid of an external passage 54, in order, for example, to reduce production costs, since the flow at downstream of the condensate can obviate the need for external passages 54 in the blade modules 14 located above the rotor shaft. Furthermore, some pallet modules 14 may be provided with pallet parts 16 without housings, so as to, for example, further reduce production costs. Alternatively, and as shown in the embodiment of Figures 2 to 3 and 5 to 10, the blade modules 14 can be identical to each other. This feature offers many advantages. For example, the production process is made more uniform. Furthermore, the maintenance of the steam turbine 10 is more convenient, since during the repair or replacement of a single blade module 14 according to the exemplary embodiment, a single spare number is required since all the blade modules 14 are identical in the interior. of the stator vane ring 12.

Additionally, to save on cost of stator vane diaphragms that may need maintenance or replacement, 14 vane modules provide a single component design, making installation and / or replacement easier than vane diaphragm rings. of conventional stator. As shown in Figures 2, 3 and 8 to 10, the outer part 52 of each stator blade module 14 is attached directly to the steam turbine 10. Specifically, each outer part 52 includes an upstream groove 56 and an upstream groove. downstream 58. The steam turbine 10 includes an upstream ridge 62 attached to a groove 56 and a downstream ridge 64 attached to a groove 58. The groove 56 is moved closer to the interior 38 than to the groove 58. The movement between the grooves 56 and 58 can allow each stator vane module to better conform to the desired flow path of steam through the steam turbine 10, and may also prevent a technician from inadvertently installing a vane module 14 in the incorrect orientation during making or maintaining the stator vane ring 12.

As shown in Figures 2 and 3, the outer passage 54 opens to a surface of the steam turbine 10 between the ridge 62 and the ridge 64. Note that there is a chamber 76 between the outer surface of the vane ring 12 and the surface of the steam turbine 10. The chamber 76 can facilitate the useful collection of condensate which escapes from the external passages 54.

A groove 66, present in each inner 38, forms a continuous circular groove facing a center of a vane ring of the stator 12, as shown in Figures 2, 3 and 5 to 7. As shown in Fig. 3, each groove 66 is secured by a metal ring 68 which closes together the blade modules of the stator 14.

As further shown in Figures 2, 3 and 5 to 7, the inner part 38 of each vane module of the stator 14 defines an inner brazing platform 72 which surrounds the first longitudinal end of each vane part 16. Also, as shown in Figures 2, 3 and 8 to 10, the outer part 52 of each vane module of the stator defines an external brazing platform 74 which surrounds the second longitudinal end of each vane part 16.

The brazing platforms 72 and 74 provide a useful surface for brazing the ends of each part of the blades 16 as well as defining a part of a stage and / or the steam flow path within the steam turbine 10. It is noted from Figures 2 and 3 that the brazing platform 74 of each outer part 52 transits uniformly towards the surrounding surfaces of the steam turbine 10.

In the embodiment of Figures 2 to 4, the vane shell part 18 can be vacuum brazed to the vane shell part 22. The first and second longitudinal ends of the resulting vane part 16 can be subsequently vacuum brazed to the part. 38 and to the exterior 52 of each vane module of the stator 14. The vacuum brazing equipment used to perform the vacuum brazing of the diaphragm 14 may be standard equipment, such as that disclosed by U.S. Pat. 4,874,918 and 4,401,254, the publications of which are included herein by reference.

Therefore, according to an exemplary embodiment shown in Fig. 11, a method (1000) for constructing a vane module for a vane ring of a stator, where the vane module comprises an elongated vane part, may include the steps of: brazing (1002) of the first and second edges of a first blade shell part and of a second blade shell part, so as to form a longitudinal passage; formation (1004) of a direct hole in the internal part; forming (1006) of an inner passage in the inner part extending from a surface of the inner part to the through hole; brazing (1008) of a first longitudinal end of the blade portion to the surface of the inner portion, so that this longitudinal passage communicates with the inner passage; forming (1010) of an external passage in the external part extending from a first surface to a second surface of the external part; and brazing (1012) of a second longitudinal end of the blade portion to the first surface of the outer portion, so that the longitudinal passage communicates with the outer passage.

The exemplary embodiments described above are intended to illustrate to all effects, but not in a restrictive sense, the present invention. Therefore, the present invention admits many variations in the manufacturing phase, which can be easily deduced by a person skilled in the art on the basis of the description contained therein. All the aforementioned variations and modifications are considered to fall within the scope and spirit of the present invention, as defined by the claims set forth below. No element, act or instruction used in the description of the present application is to be construed as critical or essential for the purposes of the invention, unless it is explicitly described as such. Furthermore, in this document the indefinite article is understood to include one or more objects.

Claims (10)

CLAIMS / CLAIMS 1. A stator vane ring in a steam turbine comprises: a plurality of stator blade modules defining an annular chamber, with each stator blade module consisting of an elongated blade portion provided with a first blade shell portion and a second blade shell portion brazed to said first blade shell portion. Said elongated blade part further comprises a longitudinal passage and at least one opening which extends at least from the first blade shell part and from the second blade shell part to the longitudinal passage; an inner part brazed to a first longitudinal end of said blade part, said inner part comprises a direct hole forming a part of said annular chamber, the inner part further includes an inner longitudinal passage extending from said direct hole to said passage longitudinal; and an outer portion brazed to a second longitudinal end of said blade portion and secured to said steam turbine, said outer portion comprises an outer passage communicating with a surface of said steam turbine and said longitudinal passage. 2. The stator vane ring of claim 1, wherein said outer portion includes a first groove configured to attach a first ridge to said surface of said steam turbine and a second groove configured to secure a second ridge to said surface of said steam turbine. steam turbine. 3. The stator vane ring of claim 2, wherein said first groove and said second groove are displaced relative to said inner portion. 4. The stator vane ring of claim 3, wherein a groove in said interior of each said vane module forms a circular groove in said stator vane ring which is secured by a metal ring to lock said together. plurality of modules for pallets. 5. The stator vane ring of claim 4, with said circular groove facing the center of said vane ring. 6. A multistage steam turbine including: a rotor assembly provided with at least one impeller; a bearing connected to the rotor assembly, which supports it in rotation; a stator vane ring for the last stage of the steam turbine having a plurality of stator vane modules defining an annular chamber. Each pallet module includes at least an elongated blade portion provided with a first blade shell portion and a second blade shell portion brazed to said first blade shell portion; an internal part brazed to a first longitudinal end of at least said part of blades, said internal part comprises a direct hole which forms a part of said annular chamber; And an outer portion brazed to a second longitudinal end of at least said blade portion and secured to a surface of said steam turbine; wherein said blade portion of at least one of said blade modules includes a longitudinal passage and an opening for allowing vapor condensate to enter said longitudinal passage, and said inner portion of at least one of said blade modules includes an internal passage extending from said hole directed to the longitudinal passage, so that said vapor condensate flows between said annular chamber and said longitudinal passage; And where said blade portion of at least one other of said blade modules includes a longitudinal passage, said interior portion of said other blade module includes an internal passage extending from said direct hole to said longitudinal passage to allow vapor condensation to flow flow between said annular chamber and said longitudinal passage, and said external part of said other blade module comprises an external passage which extends from said longitudinal passage and opening to said surface of said turbomachinery, so that the steam condensate escapes from said stator blade ring. 7. The steam turbine of claim 6, wherein a first groove in said outer portion of each said blade module is secured by a first metal ridge to said surface of said steam turbine. 8. The steam turbine of claim 7, wherein a second groove in said outer portion of each said blade module is secured by a second metal ridge to said surface of said steam turbine. The steam turbine of claim 8, wherein a first groove is located upstream and a second groove is located downstream of an operating fluid flow of said steam turbine. 10. A method of manufacturing a vane module for a stator vane ring in the last stage of a steam turbine, wherein the vane module comprises an elongated vane portion, an inner portion and an outer portion. This method provides: brazing the first and second edges of a first blade shell part to the first and second edges of a second blade shell part so as to form a longitudinal passage in said elongated blade portion; formation of a direct hole in the internal part; forming an internal passage in said internal part extending from a surface of said internal part to said direct hole; brazing a first longitudinal end of said portion of blades to said surface of said inner portion so that the longitudinal passage communicates with said inner passage; forming an external passage in said external part extending from a first surface to a second surface of said external part; And brazing a second longitudinal end of said portion of blades to said first surface of said outer portion so that the longitudinal passage communicates with said outer passage. CLAIMS / CLAIMS 1. A stator blade ring for a steam turbine, said stator blade ring comprising: a plurality of stator blade modules defining an annular chamber, each stator blade module comprising, an elongated blade portion including a first blade shell portion and a second blade shell portion brazed to said first blade shell portion, said elongated blade portion further including a longitudinal passageway and at least one opening extending through at least one of said first blade shell portion and said second blade shell portion to said longitudinal passageway; an inner portion brazed to a first longitudinal end of said blade portion, said inner portion including a through hole forming a portion of said annular chamber, said inner portion further including an inner passageway extending from said through hole to said longitudinal passageway; and an outer portion brazed to a second longitudinal end of said blade portion and engaged to said steam turbine, said outer portion including an outer passageway open to a surface of said steam turbine and said longitudinal passageway. 2. The stator blade ring of claim 1, wherein said outer portion includes a first groove configured to engage a first ridge in said surface of said steam turbine and a second groove configured to engage a second ridge in said surface of said steam turbine. 3. The stator blade ring of claim 2, wherein said first groove and said second groove are offset relative to said inner portion. 4. The stator blade ring of claim 3, wherein a groove in said inner portion of each said blade module forms a circumferential groove in said stator blade ring and said circumferential groove is engaged by a metal ring for locking said plurality of blade modules together. 5. The stator blade ring of claim 4, wherein said circumferential groove faces inwardly towards a center of said stator blade ring. 6. A multi-stage steam turbine comprising: a rotor assembly including at least one impeller; a bearing connected to, and for rotatably supporting, the rotor assembly; a stator blade ring for the last stage of the steam turbine having a plurality of stator blade modules defining an annular chamber, each blade module comprising, at least one elongated blade portion including a first blade shell portion and a second blade shell portion brazed to said first blade shell portion; an inner portion brazed to a first longitudinal end of said at least one blade portion, said inner portion including a through hole forming a portion of said annular chamber; and an outer portion brazed to a second longitudinal end of said at least one blade portion and engaged to a surface of said steam turbine; wherein said blade portion of at least one of said blade modules includes a longitudinal passageway and an opening for steam condensate to enter said longitudinal passageway, and said inner portion of said at least one blade module includes an inner passageway extending from said through hole to said longitudinal passageway for said steam condensate to flow between said annular chamber and said longitudinal passageway; and wherein said blade portion of another of said at least one of said blade modules includes a longitudinal passageway, said inner portion of said another blade module includes an inner passageway extending from said through hole to said longitudinal passageway for allowing said steam condensate to flow between said annular chamber and said longitudinal passageway, and said outer portion of said another blade module includes an outer passageway extending from said longitudinal passageway and opening to said surface of said turbo machine for allowing said steam condensate to flow out of said stator blade ring. 7. The steam turbine of claim 6, wherein a first groove in said outer portion of each said blade module is engaged by a first ridge on said surface of said steam turbine. 8. The steam turbine of claim 7, wherein a second groove in said outer portion of each said blade module is engaged by a second ridge on said surface of said steam turbine. 9. The steam turbine of claim 8, wherein said first groove faces upstream and said second groove faces downstream of a flow of working fluid within said turbo machine. 10. A method of making a blade module for a stator blade ring in the last stage of a steam turbine, the blade module including an elongated blade portion, an inner portion, and an outer portion, said method comprising: brazing first and second edges of a first blade shell portion to first and second edges of a second blade shell portion to form a longitudinal passageway in said elongated blade portion; forming a through hole in said inner portion; forming an inner passageway in said inner portion extending from a surface of said inner portion to said through hole; brazing a first longitudinal end of said blade portion to said surface of said inner portion such that said longitudinal passageway is open to said inner passageway; forming an outer passageway in said outer portion extending from a first surface to a second surface of said outer portion; and brazing a second longitudinal end of said blade portion to said first surface of said outer portion such that said longitudinal passageway is open to said outer passageway.