Compressors and systems incorporating compressors have been developed and are often utilized in a myriad of industrial processes (e.g., petroleum refineries, offshore oil production platforms, and subsea process control systems). Conventional compressors may be configured to compress a process fluid by applying kinetic energy to the process fluid to transport the process fluid from a low pressure environment to a high pressure environment. The compressed process fluid discharged from the compressors may be utilized to efficiently perform work or operate one or more downstream processes. Improvements in the efficiency of conventional compressors has increased the application of the compressors at various oil production sites. Many of the oil production sites (e.g., offshore), however, may be constrained or limited in space. Accordingly, there is an increased interest and demand for smaller and lighter compressors, or compact compressors. In addition to the foregoing, it is often desirable that the compact compressors be capable of achieving higher compression ratios (e.g., 10:1 or greater) for increased production while maintaining a compact footprint.
As the compression ratios of the compact compressors increase, the heat generated through compression may also correspondingly increase. Improper management of the increased heat of compression may adversely affect the reliability and/or performance of the compact compressors. For example, one or more components (e.g., seals) of the compact compressors may be at least partially fabricated from a material (e.g., an elastomer) that may not be capable of operating at relatively high temperatures (e.g., greater than about 380° F./193° C.) for extended periods of time. Accordingly, the increased heat generated via compression may often limit or reduce the operational lifetimes of the components. In another example, the components (e.g., impellers) of the compact compressors may not have the metallurgical properties (e.g., strength and/or fatigue life) to operate unless the respective temperatures thereof are maintained at or below design temperatures.
In view of the foregoing, skilled artisans have attempted to manage and/or counteract the heat of compression by utilizing a heat transfer medium or a cooling fluid. For example, the cooling fluid may often be circulated through one or more portions of conventional compact compressors to cool the components of the compact compressors. The circulation of the cooling fluid, however, may not sufficiently manage the heat generated in compact compressors having relatively higher compression ratios (e.g., about 10:1 or greater).
What is needed, then, is a balance piston with a sealing member for managing heat generated in a compact compressor having a relatively high compression ratio.
Embodiments of the disclosure may provide a balance piston for a compressor. The balance piston may include an annular body and a seal extending from an axial surface of the annular body. The annular body may be configured to be disposed about and coupled with a rotary shaft of the compressor. The seal may be configured to form a sealing engagement with at least one component of the compressor to prevent a flow of a process fluid from an impeller of the compressor to a seal cavity of the compressor.
Embodiments of the disclosure may also provide a compressor configured to provide a compression ratio of at least about 8:1. The compressor may include a casing and a rotary shaft disposed in the casing and configured to be driven by a driver. The compressor may also include a shaft seal assembly disposed radially outward from the rotary shaft and at least partially defining a seal cavity, and an impeller coupled with the rotary shaft and configured to receive a process fluid and discharge the process fluid at an absolute Mach number of about 1.0 or greater. The compressor may further include a balance piston integral with the impeller, and a balance piston seal disposed radially outward from the balance piston such that the balance piston seal and the balance piston define a radial clearance therebetween. The compressor may also include a protrusion coupled or integral with the balance piston. The protrusion may be configured to prevent a flow of a process fluid from the radial clearance to the seal cavity.
Embodiments of the disclosure may provide a compression system including a driver and a compressor coupled with the driver via a drive shaft and configured to provide a compression ratio of at least about 8:1. The compressor may include a casing and an inlet coupled or integral with the casing. The inlet and the casing may at least partially define a fluid pathway of the compressor configured to receive a process fluid. The compressor may also include a rotary shaft disposed in the casing and coupled with the driver via the drive shaft. The rotary shaft may be configured to be rotated by the driver via the drive shaft. The compressor may further include a shaft seal assembly disposed radially outward from the rotary shaft and at least partially defining a seal cavity. An impeller may be coupled with the rotary shaft and configured to receive the process fluid and discharge the process fluid at an absolute Mach number of about one or greater. The compressor may also include a balance piston integral with the impeller and a balance piston seal disposed radially outward from the balance piston such that the balance piston seal and the balance piston define a radial clearance therebetween. A protrusion may be coupled or integral with the balance piston and configured to prevent a flow of the process fluid from the radial clearance to the seal cavity.
The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.
Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Further, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.
The compressor 102 may be a direct-inlet centrifugal compressor. The direct-inlet centrifugal compressor may be, for example, a version of a Dresser-Rand Pipeline Direct Inlet (PDI) centrifugal compressor manufactured by the Dresser-Rand Company of Olean, N.Y. The compressor 102 may have a center-hung rotor configuration or an overhung rotor configuration, as illustrated in
The compressor 102 may include one or more stages (not shown). In at least one embodiment, the compressor 102 may be a single-stage compressor. In another embodiment, the compressor 102 may be a multi-stage centrifugal compressor. Each stage (not shown) of the compressor 102 may be a subsonic compressor stage or a supersonic compressor stage. In an exemplary embodiment, the compressor 102 may include a single supersonic compressor stage. In another embodiment, the compressor 102 may include a plurality of subsonic compressor stages. In yet another embodiment, the compressor 102 may include a subsonic compressor stage and a supersonic compressor stage. Any one or more stages of the compressor 102 may have a compression ratio greater than about 1:1. For example, any one or more stages of the compressor 102 may have a compression ratio of about 1.1:1, about 1.2:1, about 1.3:1, about 1.4:1, about 1.5:1, about 1.6:1, about 1.7:1, about 1.8:1, about 1.9:1, about 2:1, about 2.1:1, about 2.2:1, about 2.3:1, about 2.4:1, about 2.5:1, about 2.6:1, about 2.7:1, about 2.8:1, about 2.9:1, about 3:1, about 3.1:1, about 3.2:1, about 3.3:1, about 3.4:1, about 3.5:1, about 3.6:1, about 3.7:1, about 3.8:1, about 3.9:1, about 4:1, about 4.1:1, about 4.2:1, about 4.3:1, about 4.4:1, about 4.5:1, about 4.6:1, about 4.7:1, about 4.8:1, about 4.9:1, about 5:1, about 5.1:1, about 5.2:1, about 5.3:1, about 5.4:1, about 5.5:1, about 5.6:1, about 5.7:1, about 5.8:1, about 5.9:1, about 6:1, about 6.1:1, about 6.2:1, about 6.3:1, about 6.4:1, about 6.5:1, about 6.6:1, about 6.7:1, about 6.8:1, about 6.9:1, about 7:1, about 7.1:1, about 7.2:1, about 7.3:1, about 7.4:1, about 7.5:1, about 7.6:1, about 7.7:1, about 7.8:1, about 7.9:1, about 8.0:1, about 8.1:1, about 8.2:1, about 8.3:1, about 8.4:1, about 8.5:1, about 8.6:1, about 8.7:1, about 8.8:1, about 8.9:1, about 9:1, about 9.1:1, about 9.2:1, about 9.3:1, about 9.4:1, about 9.5:1, about 9.6:1, about 9.7:1, about 9.8:1, about 9.9:1, about 10:1, about 10.1:1, about 10.2:1, about 10.3:1, about 10.4:1, about 10.5:1, about 10.6:1, about 10.7:1, about 10.8:1, about 10.9:1, about 11:1, about 11.1:1, about 11.2:1, about 11.3:1, about 11.4:1, about 11.5:1, 11 3.6:1, about 11.7:1, about 11.8:1, about 11.9:1, about 12:1, about 12.1:1, about 12.2:1, about 12.3:1, about 12.4:1, about 12.5:1, about 12.6:1, about 12.7:1, about 12.8:1, about 12.9:1, about 13:1, about 13.1:1, about 13.2:1, about 13.3:1, about 13.4:1, about 13.5:1, about 13.6:1, about 13.7:1, about 13.8:1, about 13.9:1, about 14:1, or greater. In an exemplary embodiment, the compressor 102 may include a plurality of compressor stages, where a first stage (not shown) of the plurality of compressor stages may have a compression ratio of about 1.75:1 and a second stage (not shown) of the plurality of compressor stages may have a compression ratio of about 6.0:1.
The driver 104 may be configured to provide the drive shaft 106 with rotational energy. The drive shaft 106 may be integral or coupled with a rotary shaft 108 of the compressor 102 such that the rotational energy of the drive shaft 106 may be transmitted to the rotary shaft 108. The drive shaft 106 of the driver 104 may be coupled with the rotary shaft 108 via a gearbox (not shown) having a plurality of gears configured to transmit the rotational energy of the drive shaft 106 to the rotary shaft 108 of the compressor 102. Accordingly, the drive shaft 106 and the rotary shaft 108 may spin at the same speed, substantially similar speeds, or differing speeds and rotational directions via the gearbox. The driver 104 may be a motor, such as a permanent magnetic electric motor, and may include a stator (not shown) and a rotor (not shown). It should be appreciated, however, that other embodiments may employ other types of motors including, but not limited to, synchronous motors, induction motors, and brushed DC motors, or the like. The driver 104 may also be a hydraulic motor, an internal combustion engine, a steam turbine, a gas turbine, or any other device capable of driving or rotating the rotary shaft 108 of the compressor 102.
The compression system 100 may include one or more radial bearings 110 directly or indirectly supported by a housing 112 of the compression system 100. The radial bearings 110 may be configured to support the drive shaft 106 and/or the rotary shaft 108. The radial bearings 110 may be oil film bearings. The radial bearings 110 may also be magnetic bearings, such as active magnetic bearings, passive magnetic bearings, or the like. The compression system 100 may also include one or more axial thrust bearings 114 disposed adjacent the rotary shaft 108 and configured to control the axial movement of the rotary shaft 108. The axial thrust bearings 114 may be magnetic bearings configured to at least partially support and/or counter thrust loads or forces generated by the compressor 102.
The process fluid pressurized, circulated, contained, or otherwise utilized in the compression system 100 may be a fluid in a liquid phase, a gas phase, a supercritical state, a subcritical state, or any combination thereof. The process fluid may be a mixture, or process fluid mixture. The process fluid may include one or more high molecular weight process fluids, one or more low molecular weight process fluids, or any mixture or combination thereof. As used herein, the term “high molecular weight process fluids” refers to process fluids having a molecular weight of about 30 grams per mole (g/mol) or greater. Illustrative high molecular weight process fluids may include, but are not limited to, hydrocarbons, such as ethane, propane, butanes, pentanes, and hexanes. Illustrative high molecular weight process fluids may also include, but are not limited to, carbon dioxide (CO2) or process fluid mixtures containing carbon dioxide. As used herein, the term “low molecular weight process fluids” refers to process fluids having a molecular weight less than about 30 g/mol. Illustrative low molecular weight process fluids may include, but are not limited to, air, hydrogen, methane, or any combination or mixtures thereof.
In an exemplary embodiment, the process fluid or the process fluid mixture may be or include carbon dioxide. The amount of carbon dioxide in the process fluid or the process fluid mixture may be at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or greater by volume. Utilizing carbon dioxide as the process fluid or as a component or part of the process fluid mixture in the compression system 100 may provide one or more advantages. For example, carbon dioxide may provide a readily available, inexpensive, non-toxic, and non-flammable process fluid. In another example, the relatively high working pressure of applications utilizing carbon dioxide may allow the compression system 100 incorporating carbon dioxide (e.g., as the process fluid or as part of the process fluid mixture) to be relatively more compact than compression systems incorporating other process fluids (e.g., process fluids not including carbon dioxide). Additionally, the high density and high heat capacity or volumetric heat capacity of carbon dioxide with respect to other process fluids may make carbon dioxide more “energy dense.” Accordingly, a relative size of the compression system 100 and/or the components thereof may be reduced without reducing the performance of the compression system 100.
The carbon dioxide may be of any particular type, source, purity, or grade. For example, industrial grade carbon dioxide may be utilized as the process fluid without departing from the scope of the disclosure. Further, as previously discussed, the process fluids may be a mixture, or process fluid mixture. The process fluid mixture may be selected for one or more desirable properties of the process fluid mixture within the compression system 100. For example, the process fluid mixture may include a mixture of a liquid absorbent and carbon dioxide (or a process fluid containing carbon dioxide) that may enable the process fluid mixture to be compressed to a relatively higher pressure with less energy input than compressing carbon dioxide (or a process fluid containing carbon dioxide) alone.
As illustrated in
In another embodiment, illustrated in
The compressor 200 may include an impeller 222 disposed in the impeller cavity 208. The impeller 222 may have a hub 224 and a plurality of blades 226 extending from the hub 224. In an exemplary embodiment, illustrated in
In one or more embodiments, the process fluid at the tip 230 of the impeller 222 may be subsonic and have an absolute Mach number less than one. For example, the process fluid at the tip 230 of the impeller 222 may have an absolute Mach number less than 1, less than 0.9, less than 0.8, less than 0.7, less than 0.6, less than 0.5, less than 0.4, less than 0.3, less than 0.2, or less than 0.1. Accordingly, in such embodiments, the compressors 102, 200 discussed herein may be “subsonic,” as the impeller 222 may be configured to rotate about the longitudinal axis 228 at a speed sufficient to provide the process fluid at the tip 230 thereof with an absolute Mach number of less than one.
In one or more embodiments, the process fluid at the tip 230 of the impeller 222 may be supersonic and have an absolute Mach number of one or greater. For example, the process fluid at the tip 230 of the impeller 222 may have an absolute Mach number of at least 1, at least 1.1, at least 1.2, at least 1.3, at least 1.4, or at least 1.5. Accordingly, in such embodiments, the compressors 102, 200 discussed herein are said to be “supersonic,” as the impeller 222 may be configured to rotate about the longitudinal axis 228 at a speed sufficient to provide the process fluid at the tip 230 thereof with an absolute Mach number of one or greater or with a fluid velocity greater than the speed of sound. In a supersonic compressor or a stage thereof, the rotational or tip speed of the impeller 222 may be about 500 meters per second (mis) or greater. For example, the tip speed of the impeller 222 may be about 510 m/s, about 520 m/s, about 530 m/s, about 540 m/s, about 550 m/s, about 560 m/s, or greater.
As illustrated in
As illustrated in
As illustrated in
The inner radial surface 244 of the balance piston seal 240 may be or may provide a seal surface for the balance piston seal 240. It should be appreciated that the inner radial surface 244 may define any type of seal known in the art. For example, the inner radial surface 244 of the balance piston seal 240 may define a plurality of teeth (not shown) extending radially inward toward the outer radial surface 242 of the balance piston 232. Accordingly, the balance piston seal 240 may have a labyrinth seal along the inner radial surface 244 thereof. In another example, the inner radial surface 244 of the balance piston seal 240 may define a plurality of holes or openings (not shown). Accordingly, the balance piston seal 240 may provide a hole pattern sealing surface or a damper-type seal surface along the inner radial surface 244 thereof. In yet another example, the inner radial surface 244 may define a plurality of generally hexagonally-shaped openings (not shown) to thereby provide the balance piston seal 240 with a honeycomb seal surface along the inner radial surface 244 thereof.
The balance piston seal 240 may be coupled with (e.g., indirectly or directly) the casing 202. In at least one embodiment, the balance piston seal 240 may be directly coupled with the casing 202. In another embodiment, the balance piston seal 240 may be indirectly coupled with the casing 202 via a stationary support 248 of the balance piston seal assembly 238. The balance piston seal 240 may generally be stationary with respect to the rotary shaft 108 and the balance piston 232 coupled therewith, which may rotate relative to the balance piston seal 240. In at least one example, the balance piston seal 240 may be coupled with the stationary support 248 and/or the casing 202 via one or more mechanical fasteners (one is shown 250). Illustrative mechanical fasteners may include, but are not limited to, one or more bolts, studs and nuts, or any other mechanical fasteners known in the art. In another example, the balance piston seal 240 may be coupled with the stationary support 248 via an interference or resistance fit or interlocking connections. In at least one embodiment, the stationary support 248 may be coupled with the casing 202. In another embodiment, the stationary support 248 may form a portion of or be integral with the casing 202 of the compressor 200.
The compressor 200 may include a shaft seal assembly 252 disposed proximal the balance piston 232 and about the rotary shaft 108. The shaft seal assembly 252 may include one or more seals (two are indicated 254, 256) disposed radially outward from and coaxially aligned with the rotary shaft 108. As illustrated in
The casing 202, the shaft seal assembly 252, and/or the balance piston seal 232 may at least partially define a cavity 260 configured to receive the process fluid flowing through the radial clearance 246. As illustrated in
The compressor 200 may include a seal or sealing member 272 coupled or integral with the balance piston 232 and configured to prevent the compressed process fluid in the cavity 260 from flowing into one or more portions of the seal cavity 258. In an exemplary embodiment, the sealing member 272 may be or include a flange, a protrusion, or a tab extending from an axial surface 274 of the balance piston 232. It should be appreciated that the sealing member 272 may alternatively extend from an axial surface (not shown) of the impeller 222. As illustrated in
The body 276 of the protrusion 272 may extend annularly along the axial surface 274 of the balance piston 232. The body 276 may have any shape or profile suitable for forming a sealing engagement with the one or more components (e.g., the labyrinth seal 256, the casing 202, etc.) of the compressor 200. For example, as illustrated in
As previously discussed, the protrusion 272 may be configured to form the sealing engagement with one or more components of the compressor 200. For example, at least a portion of the body 276 (e.g., the base portion 282 and/or end portion 284) may be configured to form the sealing engagement with the labyrinth seal 256 or another component of the compressor 200. In at least one embodiment, at least a portion of the body 276 may contact the labyrinth seal 256 or any other component(s) of the compressor 200 to form the sealing engagement. In another embodiment, at least a portion of the body 276 may extend toward the labyrinth seal 256 such that the end portion 284 may be disposed proximal a seal surface of the labyrinth seal 256 to form the sealing engagement therewith. For example, as illustrated in
In an exemplary operation of the compressor 200, with continued reference to
During one or more modes of operation, at least a portion of the process fluid discharged from the impeller 222 may flow or leak from the impeller 222 to the cavity 260 via the radial clearance 246. The protrusion 272 may form a sealing engagement with the labyrinth seal 256 to prevent or reduce the flow of the process fluid from the cavity 260 to the seal cavity 258. The sealing engagement formed between the labyrinth seal 256 and the protrusion 272 may maintain the seal cavity 258 at a relatively lower temperature than the cavity 260. For example, compressing the process fluid in the compressor 200 may generate thermal energy (e.g., heat of compression) to thereby heat the process fluid discharged from the impeller 222. According, the portion of the process fluid discharged from the impeller 222 and flowing into the cavity 260 via the radial clearance 246 may have a relatively high temperature, and forming the sealing engagement between the protrusion 272 and the labyrinth seal 256 may prevent the flow of the heated process fluid from the cavity 260 to the seal cavity 258, thereby maintaining the seal cavity 258, a bore of the impeller 222, and/or the balance piston 232 at a relatively lower temperature than the cavity 260. It should be appreciated that maintaining the seal cavity 258 at a relatively lower temperature may also maintain the bore of the impeller 222, the balance piston 232, and/or the dry gas seal 254 at a relatively lower temperature. Maintaining the bore of the impeller 222 and/or the balance piston 232 at a relatively lower temperature may preserve one or more metallurgical properties (e.g., strength) of the bore of the impeller 222 and/or the balance piston 232. It should also be appreciated that maintaining the dry gas seal 254 at a relatively lower temperature may allow the compressor 200 to utilize a cost effective, standard dry gas seal in lieu of high temperature dry gas seals.
In addition to the foregoing, a cooling fluid, such as the seal gas, may be directed to the seal cavity 258 to prevent the flow of the heated process fluid from the cavity 260 to the seal cavity 258. For example, the seal gas may be directed to the seal cavity 258 to maintain the seal cavity 258 at a relatively higher pressure than the cavity 260. Accordingly, the seal gas contained in the seal cavity 258 may be discharged or purged from the seal cavity 258 to the cavity 260 via the serpentine gap 290 defined between the protrusion 272 and the labyrinth seal 256. The seal gas discharged from the seal cavity 258 may converge with the heated process fluid from the cavity 260 at or proximal the serpentine gap 290. The convergence of the pressurized seal gas with the heated process fluid and/or the purging of the seal gas from the seal cavity 258 may prevent the flow of the heated process fluid from the cavity 260 to the seal cavity 258. It should be appreciated that the pressure of the seal gas injected into the seal cavity 258 and/or the pressure of the seal cavity 258 may be regulated via an external and/or an internal device (e.g., flow control valve).
The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
This application claims the benefit of U.S. Provisional Patent Application having Ser. No. 62/139,042, which was filed Mar. 27, 2015. The aforementioned patent application is hereby incorporated by reference in its entirety into the present application to the extent consistent with the present application.
This invention was made with government support under Government Contract No. DOE-DE-FE0000493 awarded by the U.S. Department of Energy. The government has certain rights in the invention.
Number | Date | Country | |
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62139042 | Mar 2015 | US |