Rotor structure for turbomachinery with drainage / sealing arrangement in tie bolts

Abstract

A rotor structure for a turbomachinery such as a centrifugal compressor is provided. The disclosed embodiments utilize a drain / seal arrangement that effectively drains the rotor from tie bolts, enabling, for example, monitoring for incipient leaks of process fluid. Furthermore, during operation, the disclosed embodiments effectively deliver pressurized sealing fluid to the tie bolts, which effectively reduces the likelihood of process fluid escaping to the atmosphere.

Description

[0001] background

[0002] 1. Field

[0003] The disclosed embodiments relate generally to the field of turbomachinery systems, and more particularly to a rotor structure for a turbomachinery, and even more particularly to a drainage / sealing arrangement in a tie bolt.

[0004] 2. Description of Related Technology

[0005] Turbomachinery systems are widely used in the oil and gas industry, such as for performing compression of process fluids, conversion of thermal energy to mechanical energy, fluid liquefaction, etc. An example of such a turbomachinery system is a compressor, such as a centrifugal compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 Illustrated is a fragmentary cross-sectional view of one non-limiting embodiment of the disclosed rotor structure as may be used in industrial applications involving turbomachinery systems, such as, but not limited to, centrifugal compressors.

[0007] Figures 2 to 5 Diagrams Figure 1 , which may be used to illustrate and describe certain non-limiting structural and / or operational relationships of features in the disclosed rotor structure. DETAILED DESCRIPTION

[0008] As will be appreciated by those skilled in the art, turbomachinery systems involving rotors in a tie bolt configuration (also known in the art as a through bolt or tie rod configuration) need to be sealed so that process fluids (which may be flammable or otherwise hazardous and are pressurized by the turbomachinery (e.g., a compressor)) are inhibited from escaping to the atmosphere. In certain known rotor configurations, this sealing is typically accomplished using one or more seals (e.g., O-rings) disposed between the tie bolts and the bore of the rotor's shaft section. Thus, the respective O-rings may be subjected to the internal pressure of the process fluid on one side and to atmospheric pressure on the other side. The present inventors have recognized that such known rotor configurations lack features that would allow for monitoring incipient leakage of process fluid around the tie bolts. Additionally, such known rotor configurations lack features that would allow for transport of a sealing fluid (such as a dry seal fluid) around the tie bolts.

[0009] The disclosed embodiments utilize an innovative drain / seal arrangement that provides reliable and cost-effective drain / seal backup and / or drain / seal redundancy, such as having a feature that may be effective for draining around the tie bolts so that, for example, incipient leaks of process fluid can be monitored and, in turn, faulty seals can be appropriately and promptly replaced before escalating to an undesirable situation. The drain may be performed by a conduit drilled or otherwise constructed through a stud shaft, which effectively acts as a drain port under certain operating conditions. Additionally, such a feature may be effective for delivering a suitable pressurized sealing fluid around the tie bolts, thereby reducing the likelihood of process fluid escaping to the atmosphere. Delivery of the sealing fluid to the tie bolts may be performed by another conduit similarly drilled or otherwise constructed through the stud shaft, which effectively permits delivery of the sealing fluid to the tie bolts under certain operating conditions.

[0010] In the following detailed description, various specific details are set forth in order to provide a thorough understanding of such embodiments. However, those skilled in the art will appreciate 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 in various alternative embodiments. In other instances, methods, procedures, and components that would be fully understood by those skilled in the art have not been described in detail to avoid unnecessary and cumbersome explanations.

[0011] Furthermore, various operations may be described as multiple discrete steps implemented in a manner that facilitates understanding of the embodiments of the present invention. However, the order of description should not be interpreted as implying that the operations need to be implemented in the order in which they are presented, nor are they even order-dependent, unless otherwise indicated. Furthermore, repeated use of the phrase "in one embodiment" does not necessarily refer to the same embodiment, although it may. It should be noted that the disclosed embodiments need not be interpreted as mutually exclusive embodiments, as those skilled in the art may appropriately combine aspects of such disclosed embodiments according to the needs of a given application.

[0012] Figure 1 Illustrated is a fragmentary cross-sectional view of one non-limiting embodiment of the disclosed rotor structure 100 as may be used in industrial applications involving turbomachinery systems, such as, but not limited to, compressors (eg, centrifugal compressors, etc.).

[0013] In one disclosed embodiment, tie bolt 102 extends axially between a pressurized (e.g., relatively high pressure) process side and an atmospheric pressure side of the turbomachinery. As will be readily appreciated by those skilled in the art, a stub shaft 1041 is secured to a first end of tie bolt 102. A second stub shaft 1042 is secured to a second end of tie bolt 102. The second end of tie bolt 102 is axially opposed to the first end of tie bolt 102.

[0014] The description will proceed with respect to a first drainage / sealing arrangement disposed proximate a first end of the tie bolt 102, as shown. Figure 1 As will be appreciated by those skilled in the art, the second drainage / sealing arrangement is disposed proximate the second end of the tie bolt 102. Since the first and second drainage / sealing arrangements include the same structure and / or operational relationship, in order to avoid lengthy and cumbersome repetition, the description will be made only with respect to the first drainage / sealing arrangement disposed proximate the first end of the tie bolt 102, as shown in FIG. Figure 1 Essentially, the first and second drainage / sealing arrangements will exhibit structural symmetry relative to each other about a radial plane 101 cutting the longitudinal axis of the turbomachinery.

[0015] In one disclosed embodiment, a plurality of axially spaced annular seals 106 (such as annular seals 1061, 1062 to 106 n (eg, an O-ring) may be disposed around a section of the tie bolt 102 that corresponds to the radially inward section 108 of the respective stub shaft 102. Figure 2 , the number of annular seals illustrated is equal to 5, and therefore, in this example, n = 5. It will be appreciated that the foregoing should be interpreted as a non-limiting example.

[0016] It will be further appreciated that each respective adjacent pair of seals in the plurality of axially spaced annular seals 106 defines a sealing side of a respective chamber 109 in a plurality of axially sequential chambers (such as chambers 1091, 1092) disposed between the process side and the atmospheric pressure side of the turbomachinery. Figure 2 In the foregoing example, the annular seals 1061, 1062 to 1065 will define four axially sequential chambers. For simplicity of illustration, Figure 2-Figure 5 Only two such chambers are shown.

[0017] In general, the relationship defining the number of chambers formed by n annular seals is n - 1. Thus, if the number of annular seals is 5, the number of chambers is n - 1 = 4.

[0018] Multiple conduits 107 (such as conduits 1071, 1072 to 107 n-1 ) (e.g., bored through tie bolts or otherwise configured) extend from the radially outward section 111 of the respective stub shaft 102 through the stub shaft to communicate with a plurality of axially sequential chambers 109 disposed between the process side and the atmospheric side of the turbomachinery. In the foregoing example, the four conduits will communicate with the four chambers defined by the annular seals 1061, 1062 to 1065.

[0019] In one disclosed embodiment, the plurality of conduits 107 can alternate between a first conduit 1071 fluidly coupled at a radially outward section of the respective stub shaft 102 to receive a sealing fluid and a second conduit 1072 fluidly connected to a drain outlet at the radially outward section of the respective stub shaft. It will be appreciated that the sealing fluid source and the drain outlet can be obtained by a dry fluid seal system 130 such as is commonly used in process gas centrifugal compressors. Without limitation, the dry fluid seal system 130 can involve a tandem seal configuration involving stationary and rotatable sealing elements. As will be appreciated by those skilled in the art, the dry fluid seal system 130 can be disposed about the radially outward section 111 of the respective stub shaft 102 and, as described above, can serve as a sealing fluid source and can further be used to provide a drain mechanism for a flow that may include an incipient leak of the process fluid.

[0020] In one non-limiting embodiment, the plurality of impeller stages 140 (in Figure 1 The plurality of impeller stages are supported by tie bolts 102 using any fixing technique suitable for a given application. In one non-limiting embodiment, respective joint structures 150 may be arranged to couple adjacent impeller stages to one another. In one non-limiting embodiment, respective joint structures 150 may include, but are not limited to, coupling / stacking rotating elements such as a Hirth joint structure, a Gleason curvic joint, and a guide slot or spigot fitting joint, each of which may center the parts and transfer loads, but may also leak gas through the joint area, as will be appreciated by those skilled in the art.

[0021] In one non-limiting embodiment, the computerized leak monitor 160 may be coupled to the second conduits (eg, drain conduits 1072, 1073, etc.) to monitor any such drain conduits for the presence of any incipient leaks of process fluid.

[0022] Figures 2 to 5 Diagrams Figure 1 1 is an enlarged view of a portion of the cross-sectional view shown in , which may be used to illustrate and describe certain limiting structural and / or operational relationships of features in the disclosed rotor structure.

[0023] Figure 2 The diagram shows an example where the annular seals 1061, 1062, and 1063 are intact. That is, there is no seal failure in any of the annular seals. In this case, no fluid flow will form in the conduits 1071 and 1072. This is essentially a static condition.

[0024] Figure 3 The illustration shows an example in which annular seal 1061 is broken, while annular seals 1062 and 1063 are intact. That is, there is a seal failure in annular seal 1061. In this case, the pressurized process fluid will enter chamber 1091 through the failed annular seal 1061; the pressurized sealing fluid will flow into chamber 1091, and this will effectively inhibit the pressurized process fluid from advancing further in chamber 1091, provided that the internal pressure of the sealing fluid is relatively large compared to the internal pressure of the process fluid entering chamber 1091.

[0025] Figure 4 The illustration shows an example in which annular seal 1062 is broken, while annular seals 1061 and 1063 are intact. That is, there is a seal failure in annular seal 1062. In this case, the sealing fluid will pass through the failed annular seal 1062 and enter chamber 1092, effectively forming a fluid buffer zone overlapping chambers 1091 and 1092, wherein the fluid is discharged through conduit 1072.

[0026] Figure 5 The illustration shows an example in which annular seals 1061 and 1062 are broken, while annular seal 1063 is intact. That is, a seal failure exists in annular seals 1061 and 1062. In this case, the sealing fluid mixed with the pressurized process fluid will pass through the failed annular seal 1062, and this mixture will be discharged through conduit 1072. In this example, this mixture will not advance beyond chamber 1092.

[0027] In one non-limiting embodiment, alternating chambers 1091, 1092 to 109 n-1 The invention includes at least one alternate first chamber relative to the first chamber 1091 (e.g., the chamber is connected to the first conduit 1074 that is fluidly coupled to receive the sealing fluid), the first chamber being disposed downstream of the alternate chamber connected to the first conduit 1074. (The term downstream indicates the direction of process fluid flow between the pressurized process side and the atmospheric pressure side of the turbomachinery). Similarly, the alternate chambers 1091, 1092 to 109 n-1 At least one alternate second chamber relative to the second chamber 1092 (e.g., the chamber connected to the second conduit 1073 that is fluidly coupled for drainage) is included, the second chamber being disposed downstream of the chamber connected to the second conduit 1073. It will be appreciated that the first chamber (e.g., chamber 1091) and the alternate first chamber (e.g., chamber 1094) are each independently arranged to receive a sealing fluid, and the second chamber (e.g., chamber 1092) and the alternate chamber (e.g., chamber 1093) are each independently arranged to permit drainage, such as discussed in the context of the aforementioned examples.

[0028] In operation, for example, when the plurality of annular seals 1061, 1062 to 106 n When one or more annular seals in the corresponding adjacent seal pairs fail and the failure of the one or more annular seals causes an initial leakage of the process fluid, a first fluid flow can be established through (one or more) first conduits (e.g., conduits 1071, 1074) to transport the sealing fluid to the corresponding chamber connected to the first conduit, and / or a second fluid flow can be established through (one or more) second conduits (e.g., conduits 1072, 1073) to allow drainage of the corresponding chamber connected to the second conduit.

[0029] In operation, the disclosed embodiments utilize an innovative drainage / sealing arrangement that effectively drains the tie bolt rotor, enabling, for example, monitoring for incipient leaks of process fluid. Furthermore, in operation, the disclosed embodiments effectively deliver, for example, pressurized sealing fluid to the tie bolt rotor, which effectively reduces the likelihood of process fluid escaping to the atmosphere.

[0030] While the embodiments of the present disclosure have been disclosed in an exemplary form, it will be apparent to those skilled in the art that various modifications, additions and deletions are possible, without departing from the scope of the invention as set forth in the following claims and their equivalents.

Claims

1. A rotor structure for a turbomachinery, the rotor structure comprising: a tie bolt (102) extending axially between the pressurized process side and the atmospheric pressure side of the turbomachinery; a corresponding stub shaft (1041) secured to the first end of the tie bolt; A first drainage / sealing arrangement, comprising: a plurality of axially spaced annular seals (106) disposed about segments of the tie bolts corresponding to radially inward segments (108) of the respective stub shafts (1041), wherein each respective adjacent pair of seals of the plurality of axially spaced annular seals defines a sealing side of a respective one of a plurality of axially sequential chambers (109) disposed between the pressurized process side and the atmospheric pressure side of the turbomachinery; and a plurality of conduits (107) extending from a radially outward section (111) of the respective stub shaft (1041) through the stub shaft to communicate with the plurality of axially sequential chambers (109) disposed between the pressurized process side and the atmospheric pressure side of the turbomachinery, the plurality of conduits alternating between a first conduit (1071) fluidly coupled at the radially outward section of the respective stub shaft to receive a sealing fluid and a second conduit (1072) fluidly connected at the radially outward section of the respective stub shaft (1041) to discharge a fluid, wherein, in response to an incipient leakage flow of process fluid through one or more of the plurality of axially spaced annular seals, a first fluid flow is established through the first conduit to transport sealing fluid to a corresponding chamber in communication with the first conduit, and / or a second fluid flow is established through the second conduit to permit drainage of the corresponding chamber in communication with the second conduit.

2. The rotor structure of claim 1 , wherein the plurality of axially sequential chambers disposed between the pressurized process side and the atmospheric pressure side of the turbomachinery define a series of alternating chambers between a first chamber (1091) arranged to receive a sealing fluid and a second chamber (1092) arranged to discharge the incipient leakage of the process fluid.

3. The rotor structure according to claim 2, wherein the plurality of axially sequential chambers include at least one spare first chamber relative to the first chamber and at least one spare second chamber relative to the second chamber, the first chamber being disposed downstream of the at least one spare first chamber, and the second chamber being disposed downstream of the at least one spare second chamber, wherein the first chamber and the spare first chamber are each independently arranged to receive a sealing fluid, and wherein the second chamber and the spare second chamber are each independently arranged to permit drainage.

4. The rotor structure of claim 1, wherein a dry fluid sealing system (130) disposed about the radially outward section of the respective stub shaft comprises a sealing fluid source and a drain outlet for the incipient leakage of the process fluid. 5 . The rotor structure of claim 1 , wherein the first end of the tie bolt corresponds to the pressurized process side of the turbomachinery.

6. The rotor structure of claim 1, further comprising a second stub shaft (1042) secured to a second end of the tie bolt, the second end being axially opposite the first end of the tie bolt; A second drainage / sealing arrangement, said second drainage / sealing arrangement comprising: a further plurality of axially spaced annular seals disposed about a segment of the tie bolt corresponding to a radially inward segment of the second stub shaft (1042), wherein each respective adjacent pair of seals of the further plurality of axially spaced annular seals defines a sealing side of a respective chamber of a further plurality of axially sequential chambers disposed between the pressurized process side and the atmospheric pressure side of the turbomachinery; and a further plurality of conduits extending from a radially outward section of the second stub shaft through the second stub shaft to communicate with the further plurality of axially sequential chambers disposed between the pressurized process side and the atmospheric pressure side of the turbomachinery, the further plurality of conduits alternating between first conduits fluidly coupled at the radially outward section of the second stub shaft to receive a further sealing fluid and second conduits fluidly connected at the radially outward section of the second stub shaft to discharge a fluid, wherein, in response to flow of further incipient leakage of the process fluid through one or more of the further plurality of axially spaced annular seals, a first fluid flow is established through a first conduit of the further plurality of conduits to transport the further sealing fluid to a corresponding chamber of the further plurality of axially sequential chambers in communication with the first conduit, and a second fluid flow is established through a second conduit of the further plurality of conduits to permit drainage of the corresponding chamber in communication with the second conduit. 7 . The rotor structure of claim 6 , wherein the second end portion of the tie bolt corresponds to the atmospheric pressure side of the turbomachinery.

8. The rotor structure according to claim 6, further comprising a plurality of impeller stages (140) disposed between the stub shaft (1041) and the second stub shaft (1042), the plurality of impeller stages being supported by the tie bolts.

9. The rotor structure according to claim 8, further comprising respective joint structures (150) arranged to couple adjacent impeller stages to each other.

10. The rotor structure of claim 9, wherein the respective joint structures comprise respective Hirth joint structures.

11. The rotor structure of claim 1 , further comprising a computerized leak monitor coupled to the second conduit to monitor the presence of the incipient leak of the process fluid.

12. A centrifugal compressor comprising the rotor structure according to any one of claims 1 to 11.

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