FR2971003A1 - REINFORCEMENT SYSTEM FOR STEAM TURBINE ENVELOPE - Google Patents

Abstract

This steam turbine inner casing reinforcement system (2) comprises: an inner casing segment (4); and a reinforcing member (6) secured to and extending radially outwardly from an outer surface (8) of the inner casing segment (4), the reinforcing member (6) being adapted to support at least part of the segment (4) of inner envelope.

Description

The present invention relates to a steam turbine casing. The present invention described herein specifically relates to a steam turbine casing having a reinforcement system disposed externally. Steam turbine casings according to the prior art have reinforcement structures disposed along the inside of the inner wall of the casing. In some cases, these reinforcing structures extend over the width of the inner wall of the envelope and remain flush with the outer portion of the inner wall of the envelope. However, in all cases, these prior art reinforcing structures have reinforcing elements which extend into the vapor flow vein on the inside of the inner wall of the casing. These reinforcement structures may create problems in the steam turbine related to play and flow.

The invention provides a steam turbine casing reinforcement system. In one embodiment, the invention provides a steam turbine inner casing strengthening system comprising: an inner casing segment; and a reinforcing member secured to and extending radially outwardly from an outer surface, the reinforcing member being adapted to reinforce at least a portion of the inner casing segment. A first aspect of the invention is a steam turbine inner casing strengthening system, comprising: an inner casing segment; and a reinforcing member secured to and extending radially outwardly from said segment, the reinforcing member being adapted to reinforce at least a portion of the inner casing segment.

A second aspect of the invention is a steam turbine inner casing strengthening system, comprising: an inner casing segment having a first half and a second half; and a plurality of reinforcing elements disposed about an outer surface of the first half or second half of the inner casing segment, and extending radially outwardly from the outer surface of the first half or the second half of the inner casing segment, the different reinforcing members being adapted to reinforce the first half and / or the second half of the inner casing segment. A third aspect of the invention consists of a steam turbine comprising: a rotor member; and a stator member at least partially surrounding the rotor member, the stator member comprising: an outer casing; and an inner casing reinforcing system disposed between the outer casing and the rotor member, the inner casing reinforcing system comprising: an inner casing segment; and a reinforcing member attached to an outer surface of the inner casing segment and extending radially outwardly from the outer surface of the inner casing segment, the reinforcing member being adapted to reinforce at least a portion of the inner casing segment inner envelope segment.

The invention will be better understood from the detailed study of some embodiments taken by way of nonlimiting examples and illustrated by the appended drawings in which: FIG. 1 represents a three-dimensional perspective view of a system of strengthening of the steam turbine inner casing according to one of the embodiments of the invention; FIG. 2 is a three-dimensional perspective view of a steam turbine inner casing reinforcement system according to one embodiment of the invention; FIG. 3 represents a partial top view, cut away, of the inner casing reinforcement system according to one of the embodiments of the invention; FIG. 4 shows a fragmentary bottom cutaway view of the inner casing reinforcement system according to embodiments of the invention; FIG. 5 is a three-dimensional perspective view of a plurality of reinforcing bars, disposed at different locations around the periphery, according to one of the embodiments of the invention; and FIG. 6 is a schematic top view, cut away, of part of a steam turbine device according to one embodiment of the invention. The invention proposes a steam turbine casing. Specifically, the invention described herein relates to an inner steam turbine casing having a reinforcement system disposed on the outside. As described herein, steam turbine casings according to the prior art have reinforcing structures disposed along the interior of the inner casing wall.

In some cases, these reinforcing structures extend over the width of the wall of the inner casing and remain flush with the outer portion of the wall of the inner casing. However, in all cases, these prior art reinforcing structures include reinforcing members extending into the vapor flow vein on the inside of the inner casing wall. These reinforcing structures may cause problems of play and vapor tightness in the steam turbine. Unlike prior art reinforcing structures for steam turbine inner casings, the invention provides an outer reinforcement system for an inner steam turbine casing, having minimal consequences on the vapor flow stream. . In some embodiments, the reinforcing system includes axially extending members substantially parallel to each other, distributed (for example, fixed) in annular form around the outer surface of the inner turbine casing. steam. In other embodiments, the reinforcing system has elements extending in annular form substantially parallel to each other, axially distributed around the outer surface of the inner steam turbine casing. In the present embodiment, the reinforcing system may comprise a plurality of annular rings disposed along (eg, attached to) the outer surface of the inner casing, in the axial direction. In other embodiments, the reinforcing system includes both ring-shaped and axially-extending members, providing reinforcement along the outer surface of the inner casing. In still other embodiments, reinforcing members may extend in a partially axial and partially annular direction (ie having a non-zero axial component and a non-zero annular component) along the outer surface of the envelope interior. These elements can be combined with axial elements and / or annular elements. In any case, the technical effect of the reinforcement systems described here is to provide mechanical reinforcement for an inner casing of the steam turbine without interrupting the vapor flow vein or the sealing surfaces therein of the inner envelope. Referring to FIG. 1, there is shown a three-dimensional perspective view of a steam turbine inner casing reinforcement system 2 according to one of the embodiments. In the present embodiment, the steam turbine inner casing reinforcement system 2 comprises an inner casing segment 4 and a reinforcing element 6 (several are shown) attached to and extending radially outwardly. from an outer surface 8 (or casing outer surface) of the inner casing segment 4. In one embodiment, the reinforcing member 6 is adapted to reinforce (for example, mechanically support) at least a portion of the inner casing segment 4. The reinforcement system 2 shown and described herein has one or more radially outwardly extending reinforcing members 6 which do not extend into the vapor flow vein defined on the inner surface 10 of the segment 4 inner envelope. In one embodiment, the reinforcing member (s) 6 extend axially along the outer surface (8) of the inner casing segment (4). Thus, in some cases, the reinforcing element (s) 6 may extend in a direction substantially parallel to the axis of the steam turbine (indicated by transparency using the line A-A). This may allow axial support of the segment in the inner envelope. In some embodiments, the reinforcing member (s) 6 may extend over an axial length of more than one stage of the steam turbine (as explained later with respect to the stages shown and described with reference to the inner surface 10). Further, the reinforcing member (s) 6 may extend along or transversely over the turbine section joint segments 12 at which adjacent axial sections of the inner casing are joined. In some embodiments, the reinforcing member (s) 6 may have substantially smooth radially inwardly facing surfaces (not shown in the present embodiment), which may be adapted to substantially fit the outer surfaces substantially Smooth 8 of segment 4 of inner casing. These substantially smooth radially inwardly facing surfaces differ from the radially inward facing surfaces of prior art reinforcing structures for inner casing segments, since these prior art reinforcing structures are located along inner surfaces (e.g., inner surface 10) of the inner casing segment and are corrugated to assemble with internal parts of the vapor flow vein. In one embodiment, at least one reinforcing member 6 may include a fastener 14 adapted to receive a moving means (not shown) for causing movement of the inner envelope segment 4. In one embodiment, the fastening member 14 may be a loop (closed or adaptable to open), a hook, a notch, etc., adapted to receive a moving means, which may likewise be a loop. (Closed or adaptable to open), a hook, a notch, etc., adapted to mate with the fastener 14. One or more moving means can be attached to the fastener (s) 14 (by example, as shown, at least two in number) to cause a displacement of the inner envelope segment 4. In some cases, the fastening element (s) 14 may be configured to allow the introduction, removal and / or repositioning of the inner casing segment 4 present in a steam turbine system.

In the example shown, the inner casing segment 4 comprises a portion of an upper half of an inner steam turbine casing. In a complete interior steam turbine section, this inner assembly envelope envelope segment 4 (inner per side will be horizontal, for example, joined, at one surface level a second envelope segment a lower half of an internal steam turbine casing around the inner vapor shell), which will form one or more of a rotor. As shown, segment 4 (and its corresponding lower shell segment, shown and described with reference to FIG. 2) is part of a dual-flow steam turbine system. However, the principles described here can be applied equally well to axial flow steam turbine systems. In the inner casing segment there is also included an inlet 16 for receiving a stream of steam via a stream 18 of vapor flow. In the case where the inner casing segment 4 is an upper half of a double-flow steam turbine inner casing segment (e.g., in a low pressure section), the inlet 16 will allow steam to flow in the flow channel 18 and to be divided between sections of the steam turbine axially forward and axially rearward. The inlet 16 has an outer surface 20 and an inner surface (not shown) and, in some embodiments, a reinforcing element 6 may be attached to an outer surface 20 of the inlet 16. In one embodiment, the reinforcing element (s) 6 may extend axially over the entire surface (these elements are sometimes referred to herein as axially extending reinforcing elements), whereas in another embodiment the reinforcing element (s) 6 may extend at least partially radially on the surface of the inlet 16 (for example, substantially parallel to the flow duct 18). In another embodiment, the axially extending reinforcing member (s) 6 may comprise, or cooperate with, one or more annular extension reinforcing members 22, adapted to provide radial support for the inner casing segment 4. In some cases, ring-extending reinforcing members 22 may be assembled with axially extending reinforcing members 6 by means of welds, pins, clamps, collars, etc. In other cases, these reinforcing elements (6, 22) may be molded or integrally formed from continuous pieces of material. As described herein, the reinforcing elements (for example, the axially extending reinforcing elements 6 and / or the annularly extending reinforcing elements 22) may be of metal (eg steel) or composite material capable of providing support of the inner envelope segment. Although the reinforcing elements (for example, the axially extending reinforcing elements 6 and / or the annularly extending reinforcing elements 22) are shown substantially parallel or substantially perpendicular to the central axis A of the steam turbine, a or a plurality of reinforcing members may be adapted to extend at least partially in an annular direction and at least partially in an axial direction along the outer surface 8 (for example, diagonally between portions of the outer surface). In this case, the reinforcing element can provide both axial and radial support for the inner casing segment 4. The axially extending reinforcing member (s) described herein may allow axial reinforcement of the inner casing segment 4, which facilitates the retention of axial seals formed between one or more casing segments (e.g. inner envelope and an adjacent segment, described later). However, in certain embodiments where the inner steam turbine casing is radially sealed, the annular-extending reinforcing members 22 may contribute to retaining radial seals formed between one or more casing segments. Referring to FIG. 2, there is shown a three-dimensional perspective view of a steam turbine inner casing reinforcement system 24 according to one of the embodiments of the invention. In the present embodiment, the inner casing reinforcement system 24 includes a second inner casing segment 26 (for example, a lower half of an inner casing segment adapted to assemble with the casing segment 4). inner casing of Figure 1). Identical numerical references from one figure to another designate substantially identical elements. As shown, the inner casing reinforcement system 24 includes reinforcing bars 28 designed to retain the inner casing segment 26 in an outer casing segment (e.g., a lower outer casing segment), a manner known in the art. As similarly described with reference to FIG. 1 and inner casing segment 4, one or more reinforcing bars 6 may be disposed around one or more of the outer surfaces 8 of the second inner casing segment 26, thereby providing support for the second inner casing segment 26. On the other hand, annular extension reinforcing bars 22 may also be arranged around one or more of the outer surfaces 8 of the second inner casing segment 26, for example to provide radial support. Referring to FIGS. 3 and 4, there is shown respectively a partial top view, cut away, of the reinforcement system 2 of the inner envelope (comprising the segment 4 of the inner envelope) and a partial bottom view, cut away, of the system. reinforcement 24 of inner casing (comprising the second segment 26 of inner casing), according to one of the embodiments of the invention. The inner envelope is also sometimes called "box" afterwards. For convenience to refer to Figures 3 and 4, the inner envelope segment 4 is called the upper envelope segment while the second inner envelope segment 26 is called the lower envelope segment. The upper casing segment 4 and the lower casing segment 26 comprise a plurality of vapor flow channels 30, which extend substantially annularly around a rotor device (not shown to make the casing). clearer illustration). Thus, the vapor flow channels 30 shown in FIGS. 3 and 4 extend between the lower shell segment 26 and the upper shell segment 4 so as to create a continuous steam flow vein around the central axis A (indicated by transparency) when the envelope segments are joined. The vapor flow channels 30 are separated by side-flanged annular rings 32, which provide isolation from the fluid between the different stages of the low-pressure steam turbine. As described in more detail here, the side flange crowns 32 extend substantially radially inwardly from the wall of the inner casing and help define the vapor flow channels. Unlike the prior art inner shell reinforcement systems, the invention allows a minimal incidence on the vapor flow channels of the reinforcement system (including, for example, reinforcement bars 6 and / or the reinforcing bars 22) described here. For example, as shown in Figures 3 and 4, only a portion of the reinforcing bar 6 may extend through the inner surface 10 of the upper shell segment 4. Fig. 5 is a three-dimensional perspective view of a plurality of reinforcement bars 6, installed at different circumferential locations, according to embodiments of the invention. As described with reference to FIG. 1, the reinforcing bars 6 may have radially inwardly smooth surfaces (or faces) 34, which may be designed to snap flush against one or more outer surfaces of a segment. inner casing (for example, outer surfaces 8). In addition, as described with reference to FIG. 1, one or more reinforcement bars 6 may comprise at least one fastening element 14.

Figure 6 shows a schematic top view, cut away, of a portion of a steam turbine 36 according to one embodiment of the invention. The steam turbine 36 may comprise a rotor member 38 secured to one or more fins 40, and a stator member 42 at least partially surrounding the rotor member 38. The stator member 42 may include an outer shell 44 and a reinforcement system 46 (invisible on this broken view) of inner envelope. The inner casing reinforcement system 46 may be disposed radially inwardly of the outer casing 44 (between the outer casing 44 and the rotor member 38), and may comprise an inner casing 48 (having a plurality inner casing segments, such as inner casing segments 4, 26). The inner casing reinforcement system 46 may comprise one or more parts described with reference to the inner casing reinforcement systems 2, 24 of Figs. 1 and 2. Thus, although it is not visible from this angle of view the inner casing reinforcement system 46, part of which is included in the steam turbine device 36, may comprise one or more inner casing segments (for example, inner casing segments 4, 24) and one or more reinforcing elements (for example, the reinforcing elements 6, 22) described herein. Unlike steam turbine devices according to the prior art, the steam turbine device 36 shown according to the invention allows a strengthening of the inner casing 48 with minimal incidence on the steam flow vein between the rotor member 38 (and fins 40) and inner surfaces of inner casing 48.

List of marks 2 Reinforcement system 4 Inner shell segment 6 Reinforcement element 8 Outer surface Inner surface 12 O-ring segment 14 Fastening element 10 16 Inlet 18 Flow vein 20 Outer surface (inlet) 22 Reinforcement elements Annular Extension 24 Reinforcement System 26 Inner Casing Segment 28 Reinforcing Bars 30 Vapor Flow Channels 32 Lateral Rectangular Crowns 34 Faces 36 Steam Turbine 38 Rotor Element 40 Flaps 42 Stator Element 44 Outer Shell 46 Reinforcement system 48 Inside envelope

Claims (10)

REVENDICATIONS1. Steam turbine inner casing reinforcement system (2), comprising: an inner casing segment (4); and a reinforcing member (6) attached to an outer surface (8) of the inner casing segment (4) and extending radially outwardly from the outer surface (8) of the inner casing segment (4) the reinforcing member (6) being adapted to support at least a portion of the inner casing segment (4). Steam turbine inner casing reinforcement system (2) according to claim 1, wherein the reinforcing element (6) extends substantially axially along the outer surface (8) of the segment (4). inner envelope. The steam turbine inner casing reinforcement system (2) according to claim 1, wherein the reinforcing member (6) extends in at least partially annular direction along the outer surface (8). of the inner envelope segment (4). The steam turbine inner casing reinforcement system (2) according to claim 1, wherein the reinforcing member (6) comprises a substantially axially extending portion and a portion (22) extending in a direction having a non-zero annular component. The steam turbine inner casing reinforcement system (2) according to claim 1, wherein the inner casing segment (4) comprises a vapor inlet (16). The steam turbine inner casing reinforcement system (2) according to claim 5, further comprising a reinforcing member extending in a direction having a non-zero radial component disposed around an outer surface of the steam turbine casing. steam inlet. The vapor turbine inner casing reinforcement system (2) according to claim 5, wherein the reinforcing member (6) comprises a fastener (14) adapted to receive a displacement means for causing a moving the segment (4) of inner envelope. The steam turbine inner casing reinforcement system (2) according to claim 1, wherein the reinforcing member (6) extends through an inner surface (10) of the casing segment (4). interior. 9. Steam turbine inner casing reinforcement system (2), comprising: an inner casing segment (4) having a first half and a second half; and a plurality of reinforcing elements (6) disposed around and extending radially outwardly from an outer surface (8) of the first half or second half of the inner casing segment (4), the different reinforcing members (6) being adapted to support the first half and / or second half of the inner casing segment (4). A steam turbine (36), comprising: a rotor member (38); and a stator member (42) at least partially surrounding the rotor member (38), the stator member (42) comprising: an outer shell (44); and an inner casing reinforcement system (46) disposed between the outer casing (44) and the rotor member (38), the inner casing reinforcing system (46) comprising: a segment (4) of inner envelope; and a reinforcing member (6) attached to an outer surface (8) of the inner casing segment (4) and extending radially outwardly from the outer surface (8) of the inner casing segment (4) the reinforcing member (6) being adapted to support at least a portion of the inner casing segment (4).