Rotor structure with sealing assembly in a turbomachine and method related thereto

Abstract

A compressor rotor for a turbomachine, such as a centrifugal compressor, is provided. The disclosed embodiment includes a tie bolt and a rotor shaft cooperating with the tie bolt to define a chamber between the tie bolt and the rotor shaft. A seal assembly is positioned to separate the chamber from a first space, and a leak detector is in fluid communication with the first space and is operable to generate a signal indicating leakage of fluid from the chamber to the first space.

Description

Technical Field

[0001] The disclosed embodiments relate generally to the field of turbomachinery, and more particularly to rotor structures in turbomachines such as compressors, and even more particularly to rotor structures having seal assemblies and methods associated with the rotor structures. Background Art

[0002] Turbomachinery is widely used in many industries, such as for performing compression of process fluids, conversion of thermal energy into mechanical energy, liquefaction of fluids, etc. An example of such a turbomachinery is a compressor, such as a centrifugal compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Figure 1 A partial cross-sectional view of one non-limiting example of the disclosed rotor structure is illustrated.

[0004] Figures 2 to 3 It can be used to illustrate and describe certain non-limiting structures and / or operating relationships that can be combined with Figure 1 The illustrated embodiment is implemented with a dry fluid sealing system.

[0005] Figure 4 A partial cross-sectional view of one non-limiting embodiment of the disclosed rotor structure is illustrated, the rotor structure including a cover enclosing an end portion of a tie bolt.

[0006] Figure 5 A partial cross-sectional view of another non-limiting embodiment of the disclosed rotor structure is illustrated.

[0007] Figure 6 and Figure 7 Partial cross-sectional views of other non-limiting embodiments of the disclosed rotor structures are respectively illustrated.

[0008] Figure 8 and Fig. 9 Additional non-limiting embodiments of the disclosed rotor structures are each illustrated in partial cross-sectional views. DETAILED DESCRIPTION

[0009] As will be appreciated by those skilled in the art, a turbomachine such as a centrifugal compressor may involve a rotor of a tie bolt configuration (also referred to in the art as a through bolt or tie rod configuration), wherein the tie bolts support a plurality of impeller bodies, and wherein adjacent impeller bodies may be interconnected to one another by an elastic averaging coupling technique, such as an elastic averaging coupling technique comprising a face gear coupling or an arc tooth face coupling. These coupling types use different forms of face gear teeth (straight and curved, respectively) to form a secure connection between two components. It will be appreciated that the disclosed embodiments may be implemented with pins, tabs, or any other mechanical connection capable of transmitting torque between adjacent rotor components. That is, the disclosed embodiments are not limited to face gear couplings or arc tooth face couplings.

[0010] These couplings and associated structures may be subject to widely varying forces (e.g., centrifugal forces), such as changes from an initial rotor speed of zero revolutions per minute (RPM) to a maximum rotor speed (e.g., such as may involve tens of thousands of RPM). In addition, for example, these couplings and associated structures, which may define an internal cavity in the rotor, may be exposed to contaminants and / or byproducts that may be present in the process fluid handled by the compressor. In applications where toxic compounds are part of the process fluid, leakage of the process fluid from the rotor to the atmosphere must be appropriately suppressed.

[0011] In view of at least the foregoing considerations, the present inventors have recognized that achieving consistent high performance and long-term durability in turbomachinery, such as centrifugal compressors, may involve adequate sealing and safe routing of rotor process fluids that may leak into the rotor during compressor operation.

[0012] The disclosed embodiments may be implemented without limitation in a turbomachine including a stepped tie bolt, wherein each end of the tie bolt may extend to the atmospheric pressure side of the turbomachine. The disclosed embodiments are designed to prevent process fluids that may leak into the rotor and may flow along the tie bolt from leaking from the rotor end to the atmosphere in a cost-effective and reliable manner.

[0013] In the following detailed description, various specific details are set forth to provide a thorough understanding of such embodiments. However, it will be appreciated by those skilled in the art that the disclosed embodiments may be practiced without these specific details, that aspects of the invention are not limited to the disclosed embodiments, and that aspects of the invention may be practiced with various alternative embodiments. In other cases, methods, processes, and components that would be well understood by those skilled in the art are not described in detail to avoid unnecessary and cumbersome explanations.

[0014] In addition, various operations may be described as multiple discrete steps performed in a manner that facilitates understanding of embodiments of the present invention. However, unless otherwise stated, the order of description should not be interpreted as implying that these operations need to be performed in the order in which they are presented, nor should it be interpreted as that these operations are even dependent on order. In addition, the repeated use of the phrase "in one embodiment" does not necessarily refer to the same embodiment, although the repeated use of the phrase may refer to the same embodiment. It should be noted that the disclosed embodiments need not be interpreted as mutually exclusive embodiments, because various aspects of these disclosed embodiments can be appropriately combined by those skilled in the art according to the needs of a given application.

[0015] Figure 1 A partial cross-sectional view of a non-limiting embodiment of a disclosed rotor structure 200 for a turbomachine, such as a compressor, is illustrated, wherein the tie bolts 102 support the impeller body 106. It will be appreciated that for simplicity of illustration, Figure 1 106; however, the impeller body 106 is typically one of a plurality of impeller bodies supported by the tie bolts 102. The impeller body 106 is mechanically coupled to the rotor shaft 104 via a face gear coupling 109. In a non-limiting embodiment, the rotor shaft 104 cooperates with the tie bolts 102 to define a chamber 111 that may be located between the tie bolts 102 and the rotor shaft 104. In a non-limiting embodiment, the seal assembly 108 is positioned to separate the chamber 111 from the first space 110. In a non-limiting embodiment, the leak detector 112 may be in fluid communication with the first space 110 and may be operable to generate a signal indicating leakage of fluid from the chamber 111 to the first space 110.

[0016] In one non-limiting embodiment, the rotor shaft 104 may define a conduit 114 passing through the rotor shaft 104. The conduit 114 may be fluidly connected to the chamber 111 to transfer the fluid to, for example, the first space 110. In one non-limiting embodiment, the conduit 114 passing through the rotor shaft 104 has a first opening 116 at a radially inward surface of the rotor shaft 104 to provide fluid communication with the chamber 111. The conduit 114 has a second opening 118 at a radially outward surface of the rotor shaft 104 to provide an outlet for the fluid.

[0017] As in Figure 1 As can be appreciated in the drawings, one or more cavities 162 may be provided around the tie bolts 102 along the rotor axis 103. During operation of the compressor, process fluid (e.g., fluid compressed on the pressurized process side of the compressor) may leak into the cavity 162, and the process fluid may flow toward a lower pressure location through conduits, void gaps, spaces, etc. that may be formed around the tie bolts. This flow may be caused by Figure 1 The arrow 163 in FIG. 1 schematically indicates this.

[0018] One non-limiting function that can be provided by the seal assembly 108 is to inhibit the flow of fluid to, for example, the atmospheric pressure side of the compressor. Another non-limiting function that can be provided by the seal assembly 108 (e.g., the seal assembly 108 in combination with the conduit 114) is to direct the flow of fluid to a desired location (e.g., the first space 110) where a leak can be detected, such as by the leak detector 112. The latter function is used in the event of a breach, for example, in the first O-ring 120 of the seal assembly 108, which enables the fluid to flow into the chamber 111 and then to the conduit 114.

[0019] In one non-limiting embodiment, the seal assembly 108 includes a first O-ring 120 disposed circumferentially around the rotor shaft 104. The first O-ring 120 may be disposed on a first pressure side of the chamber 111. In this non-limiting embodiment, the seal assembly 108 also includes a second O-ring 122 disposed circumferentially around the rotor shaft 104 (and may optionally include additional O-rings 122). The second O-ring 122 may be disposed on a second pressure side of the chamber 111. The first pressure side of the chamber 111 (e.g., the side to which the first O-ring 120 is exposed) may be at a higher pressure than the second pressure side of the chamber 111 (e.g., the side to which the second O-ring 122 is exposed). By way of example, the first pressure side of the chamber 111 may correspond to a pressurized process side of the compressor, and the second pressure side of the chamber 111 may correspond to an atmospheric pressure side of the compressor.

[0020] In a non-limiting embodiment, Figure 2 and Figure 3 As shown, the dry fluid seal system 130 can be interconnected to provide an exhaust outlet for the conduit 114. As will be appreciated by those skilled in the art, dry fluid seal systems are commonly used in process gas centrifugal compressors to separate the pressurized process side of the compressor from the atmospheric side of the compressor. Certain disclosed embodiments allow for a cost-effective and innovative combination of an example embodiment of a disclosed seal assembly with a dry fluid seal system to more effectively handle leakage of fluids that might otherwise inadvertently enter the atmospheric pressure side of the compressor.

[0021] The dry fluid sealing system 130 can be in a series sealing configuration without limitation, which includes a fixed sealing element and a rotatable sealing element. The dry fluid sealing system 130 can be disposed at a radially outer section of the rotor shaft 104, and as described above, can be used to provide a discharge outlet 132 for the fluid that would otherwise leak from the chamber 111 to the space 110. In one non-limiting embodiment, the conduit 114 is fluidly connected to the dry fluid sealing system 130 to inhibit the flow of fluid to the atmospheric pressure side of the turbine. In one non-limiting embodiment, the leak detector 112 ( Figure 1 ) may be a mass flow meter that measures changes in mass flow in the exhaust outlet of the dry seal system 130. In one example application, the exhaust outlet 132 may be fluidly connected to a processing system used in conjunction with the dry fluid seal system 130, such as a flare system, for processing fluids, where the fluids may be processed by combustion.

[0022] In one non-limiting embodiment, a potential failure associated with the dry fluid seal system 130 may be evaluated based on the condition of the first O-ring 120. For example, if the first O-ring 120 is in a first condition (e.g., the first O-ring 120 is in a good condition, such as Figure 2 ), a potential fault occurs, and the potential fault indicates a real fault associated with the dry fluid sealing system 130. That is, the first condition of the first O-ring 120 indicates a real fault of the dry fluid sealing system.

[0023] In contrast, if the first O-ring 120 is in a second condition (eg, a broken first O-ring 120, such as Figure 3 Schematically shown), a potential fault occurs, then the potential fault indicates a false fault associated with the dry fluid seal system 130. Therefore, another non-limiting function that can be provided by this embodiment of the seal assembly 108 is to provide an indication that helps identify the root cause of the inconsistency associated with the dry fluid seal system. That is, the second condition of the first O-ring 120 indicates a false fault of the dry fluid seal system.

[0024] Figure 4 A partial cross-sectional view of another non-limiting embodiment of the disclosed rotor structure 200 is illustrated. In this example, the seal assembly includes a cover 150 having a closed end 152, the cover 150 enclosing an end portion 154 of the tension bolt 102, which, in the absence of the cover, would be located on the atmospheric pressure side of the compressor. In a non-limiting embodiment, the cover 150 extends axially away from the closed end 152 of the cover 150 to an open end 156 of the cover 150, which receives a portion of the rotor shaft 104.

[0025] In one non-limiting embodiment, the rotor shaft 104 may include a groove 158 configured to receive an O-ring 160 disposed circumferentially about the rotor shaft 104 to seal the open end 156 of the cover 150. Another O-ring 162 may be disposed circumferentially about the rotor shaft 104 to provide an initial sealing point for fluid that would flow from the pressurized process side of the compressor to the end portion 154 of the tie bolt 102 without being blocked by the O-ring 162, such as through a space 164, such as an air gap, between the tie bolt 102 and the rotor shaft 104 to the end portion 154 of the tie bolt 102. In this embodiment, the space 164 at least partially constitutes a chamber separated from the first space 110 by a seal assembly (e.g., a seal assembly constituted by the cover 150 and the O-rings 156, 162 in this embodiment).

[0026] In one non-limiting embodiment, the thrust ring 170 may be coupled to the cover 150 to circumferentially engage the open end 156 of the cover 150 such that, for example, a portion of the rotor shaft 104 adjacent the open end 156 of the cover 150 is engaged by a circumferential compression force provided by the thrust ring 170. That is, the open end 156 of the cover 150 may be compressively secured to the adjacent portion of the rotor shaft 104. In one non-limiting embodiment, a surface 172 of the thrust ring 170 that engages the open end 156 of the cover 150 has a frustoconical shape, as can be appreciated in the enlarged view 180.

[0027] In this embodiment, the first space 110 can be located on the atmospheric pressure side of the turbine, and a leak detector 182, such as a pressure measurement device that detects cyclic pressure changes and / or a gas monitoring probe can be disposed near the open end of the cover to generate a fluid leakage indication in the event that both O-rings 160 and 162 fail. For example, assuming that an orifice is created at a certain circumferential position of the O-ring 160, the pressure measurement device will sense a pressure increase due to leakage of the process fluid through the orifice during each revolution of the rotor. Similarly, the gas monitoring probe can be selected to detect the presence of certain molecules present in the process fluid, and this detection will provide an indication of fluid leakage from the open end of the cover.

[0028] As in Figure 5 As can be appreciated, in some embodiments, a cover (e.g., Figure 4In the embodiment of the present invention, the sealing assembly may include a first O-ring 190 disposed circumferentially around the rotor shaft 104 to provide an initial sealing point for the fluid, which, if not present, would flow from the pressurized process side of the turbine to the end portion 154 of the tightening bolt 102 through the space 164 between the tightening bolt 102 and the rotor shaft 104. In this embodiment, a second O-ring 192 disposed circumferentially around the rotor shaft 104 near the end portion 154 of the tightening bolt 102 provides a backup function so that the fluid does not escape to the atmospheric pressure side of the turbine. In this embodiment, the conduit 114 may be fluidly connected to convey the fluid to, for example, the first space 110, in which case the first space 110 may be located on the pressurized process side of the turbine. In this example, a leak detector 182, such as a pressure measurement device for detecting periodic pressure changes and / or a gas monitoring probe, may be disposed near the outlet of the conduit 114 to generate an indication of fluid leakage in the event of a failure of the O-ring 190.

[0029] In a non-limiting embodiment, Figure 6 and Figure 7 As shown, a sealing assembly 196, such as a pressure relief valve or a rupture disk, can be positioned in the conduit 114 and can be in fluid communication with the chamber 111 to transfer the leakage fluid to the first space 110, which can be located on the pressurized process side of the turbine. The pressure relief valve or rupture disk is normally in a closed state, and therefore either of these components is typically used as a seal. The pressure relief valve or rupture disk will only appear in an open state when the pressure in the chamber 111 exceeds a predetermined pressure level sufficient to set the pressure relief valve or rupture disk to an open state. The idea is to provide an ideal fluid leakage path while protecting the components of the turbomachinery from excessive pressure fluctuations that may occur during the operation of the turbine. In some embodiments, the pressure relief valve or rupture disk can be arranged to provide an audible signal indicating a fluid leakage (e.g., an audible signal of one or more frequencies, such as producing a whistle). As shown Figure 7 As shown, in some embodiments, a leak detector 182, such as a pressure measuring device and / or a gas monitoring probe for detecting cyclic pressure changes, can be optionally disposed in the first space 110 near the outlet of the pressure relief valve or rupture disk to provide an alternative (or other) form of detecting fluid leakage.

[0030] In a non-limiting embodiment, Figure 8 and Fig. 9 As shown, the corresponding rotor section can be adapted to completely prevent leakage fluid from flowing to the atmospheric pressure side of the turbine. By way of example, Figure 8The diagram illustrates a center-hung configuration of back-to-back impeller compression stages supported by a first tie bolt 102. In this embodiment, an intermediate rotor shaft segment 104' may be mechanically coupled to an adjacent impeller body 212 via a bolted face gear joint 210, which provides a gas-tight seal relative to a first space 214 that may be formed around the first tie bolt 102. The intermediate rotor shaft segment 104' may in turn be mechanically coupled to an end rotor shaft segment 104" via a face gear joint 216. The end rotor shaft segment 104" is mechanically supported by a second tie bolt 102' that communicates with the atmospheric pressure side of the turbine. A second space 218 may be formed between the end rotor shaft segment 104″ and the second tie bolt 102′ that is completely fluidly separated from the space 214. A similar sealing method may be used at the opposite end of the first tie bolt 102. As described above, a sealing assembly 196, such as a pressure relief valve or a rupture disk, may be used to avoid excessive pressure fluctuations and return leakage fluid to the pressurized process side of the turbine.

[0031] Fig. 9 The straight-through configuration of an impeller compression stage supported by a first tie bolt 102 is illustrated. In this example, a balance piston 222 mechanically coupled to an adjacent impeller body 212 via a bolted face gear joint 210 provides a gas-tight seal relative to a space 214 formed around the first tie bolt 102. The balance piston 222 is in turn mechanically coupled to an end rotor shaft segment 104" via a face gear joint 216. The end rotor shaft segment 104" is mechanically supported by a second tie bolt 102' that communicates with the atmospheric pressure side of the turbine. The space 218 formed between the end rotor shaft segment 104" and the second tie bolt 102' is completely fluidly separated from the space 214. As described above, a similar sealing method can be used at the opposite end of the first tie bolt 102. Similarly, a sealing assembly 196, such as a pressure relief valve or a rupture disk, can be used to avoid excessive pressure fluctuations and return leakage fluid to the pressurized process side of the turbine.

[0032] In operation, the disclosed embodiments allow for proper sealing and safe directing of leakage of rotor process fluid that may occur during compressor operation. In operation, the disclosed embodiments can inhibit leakage fluid from flowing to, for example, the atmospheric pressure side of the compressor, and can direct the flow of leakage fluid to a desired location where the leakage can be detected by a leak detector. In operation, certain disclosed embodiments can use a seal assembly to provide an indication that helps identify the root cause of an inconsistency associated with a dry fluid seal system.

Claims

1. A rotor structure in a turbine, the rotor structure comprising: Tighten the bolts; a rotor shaft, the rotor shaft cooperating with the tension bolt to define a chamber therebetween; a sealing assembly positioned to separate the chamber from the first space; as well as A leak detector is in fluid communication with the first space and is operable to generate a signal indicative of leakage of fluid from the chamber into the first space.

2. The rotor structure according to claim 1, wherein: The rotor shaft defines a conduit therethrough, the conduit being fluidly connected to the chamber to deliver the fluid to the first space.

3. The rotor structure according to claim 2, wherein: The seal assembly includes a first O-ring disposed circumferentially about the rotor shaft, the first O-ring disposed on a first pressure side of the chamber.

4. The rotor structure according to claim 3, wherein: The seal assembly also includes a second O-ring disposed circumferentially about the rotor shaft, the second O-ring disposed on a second pressure side of the chamber.

5. The rotor structure according to claim 4, wherein: The first pressure side is subjected to a higher pressure than the pressure subjected to the second pressure side.

6. The rotor structure of claim 3, further comprising a dry fluid seal system located about a radially outward section of the rotor shaft to separate a pressurized process side of the turbine from an atmospheric pressure side of the turbine, wherein: The conduit is fluidly connected to the dry fluid seal system to inhibit the fluid from flowing to the atmospheric pressure side of the turbine.

7. The rotor structure according to claim 6, wherein: A potential failure associated with the dry fluid seal system is evaluated based on a condition of the first o-ring, wherein a first condition of the first o-ring indicates an actual failure of the dry fluid seal system.

8. The rotor structure according to claim 7, wherein: A second condition of the first o-ring indicates a false failure of the dry fluid seal system.

9. The rotor structure according to claim 8, wherein: The first condition corresponds to an intact first O-ring, and the second condition corresponds to a broken first O-ring.

10. The rotor structure according to claim 6, wherein: The leak detector includes a mass flow meter that measures a change in mass flow in a discharge outlet of the dry fluid seal system that is fluidly connected to the conduit.

11. The rotor structure according to claim 1, wherein: The sealing assembly includes a cover having a closed end, the cover enclosing an end portion of the tension bolt, wherein the cover extends axially away from the closed end to an open end of the cover, and the open end receives a portion of the rotor shaft, wherein the rotor shaft includes a groove, the groove is configured to receive an O-ring disposed circumferentially around the rotor shaft to seal the open end of the cover.

12. The rotor structure according to claim 11, wherein: The cover comprises a generally cylindrical structure.

13. The rotor structure of claim 11, further comprising a thrust ring connected to the cover to circumferentially engage the open end of the cover, wherein The open end of the cover is compression-fixed to the portion of the rotor shaft by a circumferential compression force provided by the thrust ring.

14. The rotor structure according to claim 13, wherein: The surface of the thrust ring that engages the open end of the cover is frustoconical in shape.

15. The rotor structure according to claim 11, wherein: The first space is located on the atmospheric pressure side of the turbine, and the leak detector includes at least one of the following: a pressure measuring device that detects periodic pressure changes near the open end of the cover; and a gas monitoring probe that is arranged near the open end of the cover.

16. The rotor structure according to claim 1, wherein: The seal assembly includes a pressure relief valve or rupture disk disposed in a conduit passing through the rotor shaft, the conduit being fluidly connected to the chamber to deliver the fluid to the first space.

17. The rotor structure according to claim 16, wherein: The pressure relief valve or rupture disk is operable to produce an audible indication of a fluid leak.

18. The rotor structure according to claim 2, wherein: The leak detector includes at least one of the following: a pressure measurement device that detects periodic pressure changes near the outlet of the conduit; and a gas monitoring probe, wherein the gas monitoring probe is arranged near the outlet of the conduit.

19. The rotor structure according to claim 1, wherein: The turbomachine is a centrifugal compressor.

20. The rotor structure according to claim 1, wherein: The tie bolts include a first tie bolt, wherein a rotor section of the turbine defines a cover enclosing an end portion of the first tie bolt, wherein the tie bolts also include a second tie bolt in communication with an atmospheric pressure side of the turbine, wherein a first space formed around the first tie bolt is fluidly separated by the cover defined by the rotor section of the turbine from a second space formed between the second tie bolt and an end rotor shaft section, the end rotor shaft section being mechanically coupled to the rotor section of the turbine defining the cover.

21. The rotor structure according to claim 20, wherein: The rotor section of the turbine which defines the cover is an intermediate rotor shaft section or a compensating piston.

22. A method for evaluating a potential failure associated with a dry fluid seal system of a turbomachine, comprising: arranging a tension bolt to cooperate with a rotor shaft to define a chamber between the rotor shaft and the tension bolt; positioning a sealing assembly to separate the chamber from the first space; fluidly connecting a conduit to the chamber to convey fluid leaking from the chamber to the first space, the conduit being defined through the rotor shaft, wherein the sealing assembly comprises a first O-ring circumferentially arranged around the rotor shaft, the first O-ring being arranged on a first pressure side of the chamber, wherein the sealing assembly further comprises a second O-ring circumferentially arranged around the rotor shaft, the second O-ring being arranged on a second pressure side of the chamber; positioning the dry fluid seal system about a radially outward section of the rotor shaft between a pressurized process side of the turbine and an atmospheric pressure side of the turbine; fluidly connecting the conduit to the dry fluid seal system to inhibit the fluid from flowing to the atmospheric pressure side of the turbine; and A potential failure associated with the dry fluid sealing system is evaluated based on a condition of the first O-ring, wherein a first condition of the first O-ring indicates a real failure of the dry fluid sealing system, wherein a second condition of the first O-ring indicates a false failure of the dry fluid sealing system, wherein the first condition corresponds to an intact first O-ring and the second condition corresponds to a cracked first O-ring.

23. The method according to claim 22, wherein: The first pressure side is subjected to a higher pressure than the pressure subjected to the second pressure side.

Images