Turbomachine and method comprising a seal between an outer casing component and an inner casing component.

Abstract

This specification discloses a turbomachinery comprising an outer casing component and an inner casing component housed within and coupled to the outer casing component. A passage is provided between the inner and outer casing components, and a sealing device is positioned within the passage. The sealing device comprises an annular sealing element and a back pressure ring positioned on the low-pressure side of the annular sealing element. During use, the back pressure ring press-fits with the inner surface of the outer casing component, and the annular sealing element is in pressure contact with the back pressure ring. This specification also discloses a method for attaching the sealing device to a turbomachinery.

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to turbomachinery and components thereof. In particular, the embodiments disclosed herein relate to a turbomachine comprising an outer casing, an inner casing, and a sealing device between the inner casing and the outer casing, wherein the inner casing accommodates stationary blades and a rotor of the turbomachine. [Background Art]

[0002] Many existing turbomachines such as expanders and gas turbines include an inner casing mounted within an outer casing. The inner casing is adapted to thermally expand and contract both radially and axially relative to the outer casing due to temperature differences between the inner casing and the outer casing. The outer casing is typically split along a horizontal plane, that is, a plane containing the rotational axis of the turbomachine. A two-part casing that meets along a plane containing the rotational axis of the turbomachine is referred to as "horizontally split". The two parts of the outer casing are bolted together along flanges. The gas flow passing through the inner casing has a higher temperature than the gas flow passing through the annular space between the inner casing and the outer casing. Different temperatures of the gas flow result in different expansion rates of the inner casing and the outer casing.

[0003] The annular space between the inner and outer casings is divided into two or more annular subspaces of different pressures, and these subspaces are separated by a sealing device between the inner and outer casings (inner-outer (casing) sealing device). Due to the aforementioned different relative thermal expansion coefficients of the inner and outer casings, the inner-outer casing sealing device allows the inner and outer casings to be displaced axially and radially in the region of the sealing passage in which the sealing device is located. Unless otherwise specified, "axial" and "in the axial direction" as used herein mean parallel to the axis of rotation of the turbomachinery. "Radial," "radial," and "radial direction" mean perpendicular to the axis of rotation.

[0004] For this purpose, a leaf-shaped or membrane-type seal is provided.

[0005] If the outer casing is divided horizontally, the leaf-shaped seal can be readily manufactured in the form of a continuous ring, with one half of the outer casing fitted to the other half of the outer casing before the other half of the outer casing is fitted to surround and enclose the inner casing. The leaf-shaped seal is then housed in tangential grooves machined into the two horizontally divided portions of the outer casing.

[0006] A horizontally split outer casing can have several limitations and drawbacks in high-pressure applications. In fact, when the gas inside the outer casing is under very high pressures of tens to hundreds of bar, the bolts joining the two halves of the horizontally split casing can fail, leading to leaks.

[0007] Recently developed oxygen-fuel combustion cycles often operate with supercritical (sCO2) carbon dioxide at pressures exceeding 50 bar, and this pressure can reach several hundred bar at the peak pressure in the thermodynamic cycle. Horizontally split casings are unsuitable for this type of turbomachinery. The extremely high pressures involved in supercritical CO2 cycles necessitate the use of so-called barrel-type casings or vertically split casings. A vertically split casing consists of two casing components connected to each other by flanges and bolts along a plane perpendicular to the rotation axis of the turbomachinery. In the forward section of the turbomachinery, the outer casing component is monolithic; that is, it is in the form of a barrel with a continuous annular structure unfolding around the rotation axis of the turbomachinery. The inner-outer casing seal device, positioned in the annular space between the barrel-type outer casing component and the inner casing component, must be discontinuous in such cases to allow installation within the monolithic barrel-type outer casing component; that is, it must have a radial interruption.

[0008] Discrete annular seals are inefficient because the discontinuity in the annular seal causes gas leakage from the high-pressure region to the low-pressure region. This type of sealing device is disclosed, for example, in U.S. Publication No. 2013 / 0104565.

[0009] Improvements to the inner-outer sealing device adapted to mitigate the above-mentioned drawbacks would be welcomed in the art. [Overview of the initiative]

[0010] According to one exemplary embodiment, this specification discloses a turbomachinery comprising an outer casing component and an inner casing component housed within and coupled to the outer casing component. A passage is provided between the inner and outer casing components, and a sealing device is positioned within the passage. The sealing device comprises an annular sealing element and a back pressure ring positioned on the low-pressure side of the annular sealing element. During use, the back pressure ring press-fits with the inner surface of the outer casing component, and the annular sealing element is in pressure contact with the back pressure ring.

[0011] The annular sealing element may be monolithic; that is, it may be formed as a single, continuous, and seamless annular member to provide improved sealing efficiency. The outer casing component may be in the form of a barrel. The annular sealing element and back pressure ring may be introduced into the barrel from rear to front.

[0012] As understood herein, a barrel casing component is a component having a continuous structure around the axis of the turbomachinery and is coupled with a second casing component along a plane perpendicular to the axis of the turbomachinery.

[0013] In a further embodiment, this specification discloses a method for installing a seal between an outer casing component and an inner casing component of a turbomachinery. The method includes the steps of introducing an annular seal element into a passage between an inner casing component and an outer casing component; introducing a back pressure ring into the passage in contact with the annular seal element; and introducing an inner casing component into an outer casing component, wherein the inner casing component has a pressure surface that contacts the annular seal element.

[0014] Further features and embodiments of the turbomachinery and methods described herein are set forth below and in the appended claims. [Brief explanation of the drawing]

[0015] Here, we will briefly refer to the attached diagram. [Figure 1] This disclosure shows a cross-sectional view of an expander including a sealing device. [Figure 2] This shows an enlarged partial cross-sectional view of the sealing device of the expander shown in Figure 1 in one embodiment. [Figure 3] This shows a magnified view of a portion of the annular seal element, seen from the front. [Figure 4] An enlarged partial cross-sectional view of the seal device of the expander in Figure 1 in a further embodiment is shown. [Figure 5] An enlarged partial cross-sectional view of the seal device of the expander in Figure 1 in a further embodiment is shown. [Figure 6] A front view of a retaining ring for a sealing device of the present disclosure in one embodiment is shown. [Figure 7] A front view of a retaining ring for a sealing device of the present disclosure in a further embodiment is shown. [Modes for carrying out the invention]

[0016] In the following description, as possible exemplary embodiments of the power-generating turbomachinery described herein, we will refer specifically to expanders, and more specifically to supercritical carbon dioxide (sCO2) expanders. Such expanders can be used, for example, in the so-called Aram cycle. Nevertheless, those skilled in the art of turbomachinery will understand that the novel features disclosed herein can also be advantageously used in other power-generating turbomachinery, such as expanders using fluids other than carbon dioxide, or expanders using non-supercritical carbon dioxide, or in gas turbine engines.

[0017] The novel features disclosed herein are particularly useful in expanders operating under high pressure, for example, in thermodynamic cycles where the maximum pressure point is 50 barA or higher, e.g., 200 barA or higher, or 300 barA or higher, e.g., 800 barA or lower.

[0018] In some embodiments, the expander 3 comprises an outer casing 41 combined with a combustor 7. The combustor 7 can be accommodated inside the outer casing 41. The combustor 7 can be, for example, a can-type combustor, an annular combustor, or a can-annular combustor (also known as a cannular combustor). The combustor 7 can comprise a plurality of combustion chambers 7A arranged around the axis A-A of the expander 3.

[0019] In other embodiments not shown in the drawings, the combustor can be arranged outside the expander. In yet another embodiment, the expander may not comprise a combustor and can be used in a closed thermodynamic cycle, in which case heat is transferred to the process fluid, for example, through a heat exchanger.

[0020] In some embodiments, the outer casing 41 comprises a plurality of casing components coupled to each other. In the embodiment of Figure 1, the outer casing 41 is a so-called vertically split casing or barrel-type casing, and comprises two casing components coupled to each other along a separation plane P-P orthogonal to the rotation axis A-A of a rotor 43 rotatably supported inside the outer casing 41.

[0021] A first casing component 41.1, also referred to herein as "high-pressure casing", is coupled to a second casing component 41.2, also referred to herein as "low-pressure exhaust casing".

[0022] The high-pressure casing 41.1 is preferably a barrel casing component, that is, it is monolithic and continuous around the axis A-A of the expander.

[0023] The low-pressure exhaust casing 41.2 can be positioned on the discharge side of the expander 3, that is, on the rear side, that is, on the opposite side of the combustor 7 located on the front side of the expander 3. Accordingly, the joint between the two components forming the outer casing, that is, the plane P-P that separates the low-pressure exhaust casing 41.2 and the high-pressure casing 41.1 from each other, is arranged at a rear position, that is, in a region of the expander where the pressure of the process gas expanding through the expander is substantially lower than the maximum pressure of the thermodynamic cycle.

[0024] As used herein, the term "front" refers to the upstream end of the expander 3. The term "rear" refers to the downstream end of the expander 3 with respect to the flow direction of the process gas. Accordingly, the pressure of the process gas decreases along the expander 3 in the direction from front to rear. Since the internal gas pressure in the region of the separation plane P-P is lower than the pressure at the front end of the expander 3, arranging the separation plane P-P near the rear end of the expander 3 is particularly advantageous. This facilitates the design of the outer casing 41 and reduces difficulties involved therein.

[0025] In some embodiments, the low-pressure exhaust casing 41.2 forms an exhaust volute or an exhaust plenum 41.3, through which the exhausted process gas is discharged from the expander 3.

[0026] Reference numerals 45 and 47 indicate bearing devices that rotatably support the rotor 43. For example, the bearing device 45 on the side opposite to the combustor 7, that is, the rear side, may include an axial bearing or a thrust bearing combined with a radial bearing, or a bearing having axial-radial bearing capability. The bearing device 47 on the combustor side, that is, the front side, may include a radial bearing. A reverse arrangement, in which a bearing having axial load capability is arranged on the combustor side, is also possible. The bearing devices 45 and 47 may be housed in a bearing casing not shown in detail.

[0027] The rotor 43 is housed in an inner casing component 51, and is fixedly housed in and connected to the outer casing 41.

[0028] Since the planar PP separating the high-pressure casing 41.1 and the low-pressure casing 41.2 is located in the rear region of the expander, the inner casing 51 and rotor 43 must be introduced into the outer casing from rear to front.

[0029] In the embodiment shown in Figure 1, the expander 3 has multiple stages. As merely an example, the expander in Figure 1 includes eight stages. The number of stages shown is merely an example. Other embodiments may include fewer than eight or more stages.

[0030] Each stage comprises an annular row of fixed vanes or fixed blades 53 fixedly arranged within an inner casing component 51. Each expansion stage further includes each annular row of rotor blades 55 positioned downstream of each annular row of fixed blades 53 along an expansion flow path that extends from front to rear through multiple expansion stages of the expander 3 from the combustor 7 to the exhaust plenum 41.3.

[0031] The rotor blades 55 constitute part of the rotor 43, i.e., they are connected to rotate together with the rotor shaft. In this embodiment, each annular row of rotor blades 55 is mounted on its respective rotor disk 57.

[0032] Each rotor blade 55 can be manufactured separately from each rotor disk 57 and mechanically mounted thereon, as schematically shown in Figure 1. In other embodiments, each rotor blade 55 and rotor disk 57 can be manufactured as a monolithic body, for example by additive manufacturing. In yet another embodiment, two design options can be combined. One or more stages may include each monolithically manufactured component, including the rotor blades and disks, while one or more stages may include a rotor disk and separately manufactured rotor blades mechanically coupled to the rotor disk.

[0033] In some embodiments, the rotor discs 57 are stacked and connected to each other by tie rods. In the exemplary embodiment shown in Figure 1, the tie rods include a plurality of tie rods 61 positioned at a certain distance from the rotation axis AA, and a central tie rod 63 coaxial with the rotor 43.

[0034] In other embodiments, different arrangements of tie rods can be provided, for example, only a single central tie rod coaxial with the rotor 43 can be provided, or only a set of tie rods arranged around axis AA at radial distances from it can be provided. In yet another embodiment, tie rods can be provided at different distances from the rotating axis AA. The rotor can also be assembled in different ways, for example, by additive manufacturing, such as by welding adjacent rotor discs to each other or by machining a single workpiece.

[0035] In some embodiments, the rotor 43 further comprises a front shaft portion 65 and a rear shaft portion 67. Each of the front shaft portion 65 and the rear shaft portion 67 may include one or more sections connected to each other, for example by tie rods, as shown in the example for the front shaft portion 65.

[0036] In the embodiment shown in Figure 1, the rotor blades are mounted on rotor discs, and the rotor discs are stacked on top of each other between the front shaft portion 65 and the rear shaft portion 67. In other embodiments not shown, one or more annular rows of rotor blades may be mounted directly on (or manufactured integrally with) the front shaft portion, and / or one or more annular rows of rotor blades may be mounted directly on (or manufactured integrally with) the rear shaft portion. In some embodiments, the rotor may include a front shaft portion and a rear shaft portion connected to each other by tie rods or the like, and all stages of rotor blades may be mounted on either the front shaft portion or the rear shaft portion, or partially on the front shaft portion and partially on the rear shaft portion, without intermediate rotor discs (or manufactured integrally with the rear shaft portion).

[0037] In some embodiments, each sealing disk 68, also known as a spacing disk or spacer, is positioned between each pair of consecutive (i.e., adjacent) rotor disks 57. As used herein, the expression “torsion-connected” means a connection adapted to transmit torque between torsion-connected components so that the torsion-connected components rotate as a single unit around the rotor's axis of rotation AA.

[0038] An annular space is formed between the outer casing component 41.1 and the inner casing component 51. In the embodiment shown in Figure 1, the annular space is divided into an annular high-pressure region 81 and an annular low-pressure region 83. A seal passage 85, referred to herein simply as the “passage,” which houses the inner-outer casing seal device described in more detail below, separates the annular high-pressure region 81 and the annular low-pressure region 83. In some embodiments, a tandem or double inner-outer casing seal device can be positioned within the passage 85. A further inner-outer casing seal device 87 can be provided between the annular low-pressure region 83 and the discharge plenum 41.3.

[0039] Since the outer casing component 41.1 is a barrel and the separation surface PP is in the rear region of the expander, the inner-outer casing seal device must be introduced into the outer casing component 41.1 from rear to front before the inner casing 51 and the rotor 43 housed therein are introduced into the outer casing component 41.1.

[0040] An embodiment of an inner-outer casing seal device is shown in Figure 2, which shows an enlarged view of passage 85. In this embodiment, passage 85 accommodates a tandem or double inner-outer casing seal device. Each seal device is labeled 87. In this embodiment, the two seal devices 87 forming a tandem seal device are structurally and conceptually identical, but differ from each other in terms of the diameter of their components. Therefore, only one seal device will be described in detail.

[0041] The sealing device 87 comprises an annular sealing element 89 having a high-pressure side 89H and a low-pressure side 89L. The high-pressure side 89H is oriented toward the front of the expander 3 and faces the high-pressure region 81, and the low-pressure side 89L is oriented toward the rear of the expander 3 and faces the low-pressure region 83. The annular sealing element 89 extends 360° continuously, i.e., seamlessly and without interruption, around axis AA, and thus provides a continuous membrane type or leaf type seal. In other words, the annular sealing element 89 is a continuous monolithic element.

[0042] The annular seal element 89 comprises a radially outer annular seal region and a radially inner annular seal region. During use, the radially inner annular seal region of the annular seal element 89 is in pressure contact with the radially extending annular pressure surface 51S of the inner casing component 51. In Figure 1, the annular pressure surface 51S is perpendicular to the axis AA of the expander 3, but this is not mandatory. The annular pressure surface 51S only needs to extend radially from the radially inner edge to the radially outer edge, for example.

[0043] The radially outer annular sealing region of the annular sealing element 89 is in pressure contact with a back pressure ring 91 positioned adjacent to the low-pressure side 89L of the annular sealing element 89. Thus, the annular sealing element 89 is housed between the back pressure ring 91 and a shoulder S formed on the outer casing component 41.1 and projecting radially inward toward axis AA. The shoulder S can be manufactured by machining or formed by an annular element (one or more segments) fixed to the inner surface 41S of the outer casing component 41.1.

[0044] Just like the annular sealing element 89, the back pressure ring 91 can be a continuous monolithic ring that unfolds seamlessly 360° around axis AA without interruption.

[0045] During use, the back pressure ring 91 is press-fitted and engaged with the inner surface 41S of the outer casing component 41, that is, the surface of the outer casing component 41.1 facing the inner casing component 51.

[0046] In some embodiments, the back pressure ring 91 is made of a material having a higher coefficient of thermal expansion than the material of the outer casing component 41.1. The outer casing component 41.1 and the back pressure ring 91 can be dimensionally determined such that, when the expander 3 is inoperable and at room temperature, the back pressure ring 91 can have an outer diameter D1 that is slightly smaller, for example, a few tenths of a millimeter, than the diameter of the inner surface 41S of the outer casing component 41.1 at the position in which the back pressure ring 91 is housed. Thus, the back pressure ring 91 is housed within the outer casing 41.1 with a gap.

[0047] If the back pressure ring 91 is made of a material having a higher coefficient of thermal expansion than the material of the outer casing component 41.1, then when the expander 3 is started and hot gas flows through the expander, the back pressure ring 91 undergoes faster radial expansion than the outer casing component 41.1. This expansion causes the back pressure ring 91 to press-fit into the outer casing component 41.1. The pressure gradient between the annular high-pressure region 81 and the annular low-pressure region 83 presses the annular seal element 89 against the annular pressure surface 51S and the back pressure ring 91. The contact pressure generated between the annular seal element 89 on one side and the surface 51S and the back pressure ring 91 on the other side provides a seal against gas leakage between the annular high-pressure region 81 and the annular low-pressure region 83.

[0048] If the back pressure ring 91 is sized such that there is a gap between it and the outer casing component 41.1 at room temperature, then, for example, the back pressure ring 91 can be removed more easily for maintenance or repair purposes.

[0049] In other embodiments, the back pressure ring 91 may have an outer diameter D1 greater than or equal to the inner diameter of the outer casing component 41.1. In such cases, the back pressure ring 91 can be press-fitted into the outer casing component 41.1 by applying a temperature difference between the back pressure ring 91 and the outer casing component 41.1, for example by cooling the back pressure ring 91 to induce thermal contraction, thereby reducing the outer diameter of the back pressure ring 91.

[0050] In some embodiments, specifically when the back pressure ring 91 is mounted within the outer casing component 41.1 with a gap, a retaining device can be provided that is adapted to prevent the back pressure ring from being displaced axially within the outer casing component 41.1. In Figure 1, the retaining device may include a shear ring 93 positioned adjacent to the back pressure ring 91 on the side of the back pressure ring 91 opposite to the annular seal element 89, i.e., on the side of the back pressure ring 91 facing the annular low-pressure region 83 and the rear side of the expander 3.

[0051] In some embodiments, the shear ring 93 may be an elastic ring in the form of a sieger ring, as shown in Figure 6, which shows its front view.

[0052] In other embodiments, the shear ring 93 may comprise multiple shear ring segments, as shown in Figure 7, and a shear ring 93 comprising two shear ring segments 93A and 93B is shown.

[0053] In some embodiments, as shown in Figure 2, the shear ring 93 is housed in an annular groove 95 machined into the inner surface 41S of the outer casing component 41.1. The depth of the annular groove 95 is less than the radial thickness of the shear ring 93, so that the shear ring 93 protrudes radially outward from the annular groove 95 toward axis AA, forming a shoulder that holds the back pressure ring 91 in the correct axial position, even when the back pressure ring 91 is mounted with a gap inside the outer casing component 41.1 at room temperature.

[0054] In some embodiments, if the shear ring 93 includes a plurality of shear ring segments 93A, 93B as shown in Figure 7, the elastic feature portion 97 can be positioned between the mutually facing end faces of the shear ring segments 93A, 93B, enabling the shear ring segments 93A, 93B to be mounted in the annular groove 95 and to be held within the annular groove 95.

[0055] In some embodiments, the low-pressure side 89L of the annular seal element 89 facing the back pressure ring 91 comprises two annular ridges or protrusions 89.1 and 89.2. The ridges 89.1 and 89.2 define the contact surfaces between the annular seal element 89 and the back pressure ring 91 and the annular pressure surface 51S. The smaller contact surface defined by the ridges 89.1 and 89.2 provides a higher contact pressure and therefore a more efficient seal than that achievable with full-surface contact of the annular seal element 89, i.e., when the annular seal element 89 has flat sides that are in pressure contact with the back pressure ring 91.

[0056] The annular sealing element 89 allows the inner casing component 51 to be displaced axially and radially relative to the outer casing component 41.1 without loss of sealing efficiency. The use of ridges or projections enhances contact and thus improves sealing efficiency in the event of mutual displacement between the inner casing component 51 and the outer casing component 41.1.

[0057] In some embodiments, each of the raised portions 89.1 and 89.2 has an outward convex surface which may have the shape of a circumferential segment in a cross-sectional view. The curved convex outer surfaces of the raised portions 89.1 and 89.2 provide optimal pressure contact with the back pressure ring 91 and the pressure surface 51S, even in the case of angular displacement of the annular seal element 89.

[0058] In the embodiment of Figure 2, the annular seal element 89 is broadly planar. As understood herein, planar means that the annular seal element 89 can be placed on a plane, i.e., a flat surface, on which it contacts along at least two radially spaced circumferential lines. In the embodiment of Figure 2, the side of the annular seal element 89 facing the annular high-pressure region 81 is flat, i.e., planar. If the annular element 89 is planar, the two annular protrusions 89.1 and 89.2 contact a common geometric plane in the sense that both protrusions contact the surface along their entire circumferential extensions when the annular seal element 89 is placed on a planar (flat) surface with the protrusions 89.1 and 89.2 facing the surface.

[0059] In other embodiments not shown, the annular sealing element 89 may be conical, i.e., in the shape of a disc spring, and may be deformed to a flat state under pressure.

[0060] When the expander 3 is started during use, the temperature of the inner casing component 51 rises faster than the temperature of the outer casing component 41.1. If the back pressure ring 91 is installed in the passage 85 with some clearance at room temperature and is made of a material having a higher coefficient of thermal expansion than the outer casing component 41.1, the outer diameter of the back pressure ring 91 increases faster than the inner diameter of the surface 41S, thereby providing a shoulder that can engage with the inner surface 41S of the outer casing component 41.1 under pressure and press the annular seal element 89 against the annular seal element 89 by a pressure gradient across the annular seal element 89. The pressure gradient between the annular high-pressure region 81 and the annular low-pressure region 83 presses the annular seal element 89 against the radial pressure surface 51S and the back pressure ring 91, providing an efficient seal between the high-pressure region 81 and the low-pressure region 83.

[0061] Continuing with Figure 2, a further embodiment of the inner-outer casing seal device is shown in Figure 4. The same elements already described in relation to Figure 2 are labeled with the same reference numerals and will not be described again. The embodiment in Figure 4 differs from the embodiment in Figure 2 in that the elastic member 99 is positioned between the annular seal element 89 and the shoulder S, i.e., on the high-pressure side 89H of the annular seal element 89. The elastic member 99 biases the annular seal element 89 toward the back pressure ring 91 and toward the pressure surface 51S. When the expander 3 is not operating and the gas pressure is not holding the annular seal element 89 in a sealed contact with the back pressure ring 91 and the pressure surface 51S, the elastic member 99 ensures that the annular seal element 89 is in contact with the pressure surface 51S and the back pressure ring 91, so that at startup, the rising gas pressure in the annular high-pressure region 81 presses the annular seal element 89 against the annular pressure surface 51S and the back pressure ring 91, preventing pressurized gas from leaking through the annular seal element 89 toward the low-pressure region 83.

[0062] In some embodiments, particularly when the shear ring 93 comprises a plurality of shear ring segments 93A, 93B (see Figure 7) arranged within an annular groove 95, each shear ring segment can be mechanically coupled to the outer casing component 41.1 by a plurality of fasteners. An embodiment including fasteners adapted to hold the shear ring segments 93A, 93B in place is shown in Figure 5. The same reference numerals indicate the same or equivalent components and elements already described in Figures 1 to 4, which will not be described again. The fasteners are indicated by 101 and can be attached, for example, by screws 103 to the internal cavity of the outer casing component 41.1.

[0063] The sealing device described above includes a continuous annular sealing element 89, which can be attached to a barrel-shaped outer casing component 41.1, i.e., a casing component that extends monolithically and seamlessly around the axis AA of the turbomachinery.

[0064] If the outer diameter of the back pressure ring 91 at room temperature is smaller than the diameter of the inner surface 41S at the location where the back pressure ring 91 must be installed, the inner-outer casing seal device can be assembled as follows: If an elastic member 99 is provided, the elastic member 99 is first introduced from rear to front and positioned against the shoulder S. Next, the annular seal element 89 is introduced into the outer casing component 41.1, followed by the back pressure ring 91. These components of the seal device are then held in an axial position by the shear ring 93. If the shear ring 93 is monolithic (Figure 6), its radial dimension is reduced by approaching the two ends 93A. The shear ring 93 is introduced into the outer casing component 41.1, aligned with the annular groove 95, and released to snap into it.

[0065] If the shear ring 93 is formed by shear ring segments (Figure 7), each shear ring segment can be introduced into a groove 95 and fastened to an outer casing component 41.1 by a fastener 101, or simply held therein by an elastic feature 97.

[0066] If the sealing device is double, the second sealing device is installed in the same order. In the embodiment of Figure 5, the shoulder S of the second (downstream) sealing device is formed by a separate annular segment or annular member from the outer casing component 41.1 and is fixed to the outer casing component before the members forming the second inner-outer casing sealing device are installed.

[0067] When the turbomachine 3 starts operating, the back pressure ring 91 expands due to its higher coefficient of thermal expansion and is pressed against the inner surface 41S of the outer casing component 41.1.

[0068] If the sealing device needs to be removed, for example, to replace one or more of its components, disassembly is performed by carrying out the same operations described above in reverse order. The gap between the outer casing component 41.1 and the back pressure ring 91 at room temperature allows for easy removal of the back pressure ring 91 and the annular sealing element 89.

[0069] In other embodiments, the back pressure ring 91 may have an outer diameter such that it can be press-fitted into the outer casing component 41.1 even at room temperature. In such cases, the back pressure ring 91 may be cooled to below room temperature before installation to cause a temporary reduction in its outer diameter and enable insertion into the outer casing component 41.1.

[0070] Exemplary embodiments are disclosed above and illustrated in the accompanying drawings. Those skilled in the art will understand that various modifications, omissions, and additions can be made to those specifically disclosed herein without departing from the scope of the invention as defined in the following claims.

Claims

1. It is a turbomachinery, Outer casing components, An inner casing component housed within the outer casing component, the inner casing component having an inner surface facing the inner casing component and coupled to the outer casing component, The passage between the inner casing component and the outer casing component, An annular sealing element disposed within the passage and having a high-pressure side and a low-pressure side, A turbomachinery comprising a back pressure ring positioned on the low-pressure side of the annular seal element, wherein, during use, the back pressure ring press-fits and engages with the inner surface of the outer casing component, and the annular seal element is in pressure contact with the back pressure ring.

2. The turbomachinery according to claim 1, wherein the back pressure ring is made of a material having a first coefficient of thermal expansion, and the outer casing component is made of a material having a second coefficient of thermal expansion, wherein the first coefficient of thermal expansion is higher than the second coefficient of thermal expansion.

3. The turbomachinery according to claim 1 or 2, wherein when the turbomachinery is at room temperature, the back pressure ring has an outer diameter less than or equal to the inner diameter of the outer casing component at the axial position where the back pressure ring is positioned.

4. The turbomachinery according to any one of claims 1 to 3, wherein the annular sealing element is a continuous monolithic element.

5. The turbomachinery according to any one of claims 1 to 4, wherein the outer casing component is a barrel casing component.

6. The turbomachinery according to any one of claims 1 to 5, wherein the back pressure ring is a continuous monolithic ring.

7. The turbomachinery according to any one of claims 1 to 6, wherein the annular sealing element is planar.

8. The turbomachinery according to any one of claims 1 to 6, wherein the annular sealing element is conical in the shape of a disc spring.

9. The turbomachinery according to any one of claims 1 to 8, further comprising a retaining device adapted to prevent axial displacement of the back pressure ring.

10. The turbomachinery according to claim 9, wherein the retaining device comprises a shear ring disposed in an annular groove on the inner surface of the outer casing component, the shear ring protruding radially inward from the annular groove, and the shear ring is in contact with the back pressure ring on the side of the back pressure ring opposite to the annular seal element.

11. The turbomachinery according to claim 10, wherein the shear ring is monolithic.

12. The turbomachinery according to claim 11, wherein the shear ring is elastically snap-engaged within the annular groove.

13. The turbomachinery according to claim 10, wherein the shear ring includes a plurality of shear ring segments arranged within the annular groove.

14. The turbomachine according to claim 13, wherein the shear ring segment is mechanically coupled to the outer casing component by a plurality of fasteners.

15. The turbomachinery according to any one of claims 1 to 14, wherein the annular seal element comprises a radially outer annular seal region and a radially inner annular seal region, the radially outer annular seal region being in pressure contact with the back pressure ring, and the radially inner annular seal region being in pressure contact with a radially extending annular pressure surface of the inner casing component.

16. The turbomachinery according to claim 15, wherein the radially outer annular seal region comprises a first annular ridge protruding toward the back pressure ring and having a first annular ridge in pressure contact with the back pressure ring.

17. The turbomachinery according to claim 16, wherein the first annular protrusion has an outwardly curved convex contact surface adapted to pressure contact with the back pressure ring.

18. The turbomachinery according to claim 15, 16, or 17, wherein the radially inner annular seal region comprises a second annular ridge projecting toward the radially extending annular pressure surface of the inner casing component.

19. The turbomachinery according to claim 18, wherein the second annular protrusion has an outward curved convex contact surface adapted to pressure contact with the annular pressure surface of the inner casing component.

20. The turbomachinery according to any one of claims 1 to 19, further comprising an elastic member disposed adjacent to the annular seal element on the side of the annular seal element opposite to the back pressure ring, and adapted to bias the annular seal element with respect to the back pressure ring.

21. The turbomachinery according to any one of claims 1 to 20, wherein a pressure of 50 barA or more, preferably 800 barA or less, is present on the high-pressure side of the annular sealing element when in use.

22. The turbomachinery according to any one of claims 1 to 21, wherein the inner casing component and the outer casing component are adapted to introduce the inner casing component into the outer casing component in a rear-to-front direction.

23. A method for installing a seal between an outer casing component and an inner casing component of a turbomachinery, wherein the method is: A step of introducing an annular sealing element into the passage between the inner casing component and the outer casing component, A step of introducing a back pressure ring into the passage in contact with the annular sealing element, A method comprising the step of introducing the inner casing component into the outer casing component, wherein the inner casing component has a pressure surface that contacts the annular sealing element.

24. The method according to claim 22 or 23, wherein at room temperature, the back pressure ring has an outer diameter less than or equal to the inner diameter of the inner surface of the outer casing component.

25. The method according to claim 23 or 24, further comprising the step of fixing the back pressure ring to the outer casing component by a retaining device in order to prevent axial displacement of the back pressure ring inside the outer casing component.

26. The method according to claim 25, wherein the retaining device includes a shear ring, the shear ring is mounted in an annular groove on the inner surface of the outer casing component and protrudes therefrom.

27. The method according to any one of claims 23 to 26, wherein the annular sealing element, the back pressure ring, and the inner casing component are introduced into the outer casing component in a rearward direction.

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